bims-lysosi Biomed News
on Lysosomes and signaling
Issue of 2022‒03‒20
39 papers selected by
Stephanie Fernandes
Max Planck Institute for Biology of Ageing
  1. Rheb regulates nuclear mTORC1 activity independent of farnesylation.
  2. Single serine on TSC2 exerts biased control over mTORC1 activation mediated by ERK1/2 but not Akt.
  3. Follicular lymphoma-associated mutations in the V-ATPase chaperone VMA21 activate autophagy creating a targetable dependency.
  4. Recombinant pro-CTSD (cathepsin D) enhances SNCA/α-Synuclein degradation in α-Synucleinopathy models.
  5. eIF3a regulation of mTOR signaling and translational control via HuR in cellular response to DNA damage.
  6. Lysosomal Ca2+-mediated TFEB activation modulates mitophagy and functional adaptation of pancreatic β-cells to metabolic stress.
  7. Editorial: Molecular Aspects of Mucopolysaccharidoses.
  8. Identification of defined structural elements within TOR2 kinase required for TOR Complex 2 assembly and function in S. cerevisiae.
  9. Regulation of basal autophagy by calmodulin availability.
  10. Endolysosomal calcium release and cardiac physiology.
  11. Rab34 plays a critical role as a bidirectional regulator of osteoclastogenesis.
  12. Material properties of phase-separated TFEB condensates regulate the autophagy-lysosome pathway.
  13. Iduronate-2-sulfatase interactome: validation by yeast two-hybrid assay.
  14. TMEM106B deficiency impairs cerebellar myelination and synaptic integrity with Purkinje cell loss.
  15. The Role of Zinc in Axon Formation via the mTORC1 Pathway.
  16. Autistic-like behavior and cerebellar dysfunction in Bmal1 mutant mice ameliorated by mTORC1 inhibition.
  17. Autologous, lentivirus-modified, T-rapa cell "micropharmacies" for lysosomal storage disorders.
  18. Airway secretory cell fate conversion via YAP-mTORC1-dependent essential amino acid metabolism.
  19. Cell Type-Specific Mechanistic Target of Rapamycin-Dependent Distortion of Autophagy Pathways in Lupus Nephritis.
  20. Synaptic Vesicle Recycling and the Endolysosomal System: A Reappraisal of Form and Function.
  21. Lysosomal inhibition sensitizes TMEM16A-expressing cancer cells to chemotherapy.
  22. Pathways and Mechanisms of Cellular Cholesterol Efflux-Insight From Imaging.
  23. Hematopoietic stem cells temporally transition to thrombopoietin dependence in the fetal liver.
  24. Early secretory pathway-resident Zn transporter proteins contribute to cellular sphingolipid metabolism through activation of sphingomyelin phosphodiesterase 1.
  25. Rapamycin Improved Retinal Function and Morphology in a Mouse Model of Retinal Degeneration.
  26. Touch and Go: Membrane Contact Sites Between Lipid Droplets and Other Organelles.
  27. The needs of a synapse-How local organelles serve synaptic proteostasis.
  28. Niemann-Pick Disease Type A: A Rare Disease With a Fatal Outcome.
  29. Spine‑specific downregulation of LAPTM5 expression promotes the progression and spinal metastasis of estrogen receptor‑positive breast cancer by activating glutamine‑dependent mTOR signaling.
  30. A novel brain-penetrant oral UGT8 inhibitor decreases in vivo galactosphingolipid biosynthesis in murine Krabbe disease.
  31. A vacuolar membrane protein Vsb1p contributes to the vacuolar compartmentalization of basic amino acids in Schizosaccharomyces pombe.
  32. Neurophysiological Findings in Neuronal Ceroid Lipofuscinoses.
  33. Theranostic F-SLOH mitigates Alzheimer's disease pathology involving TFEB and ameliorates cognitive functions in Alzheimer's disease models.
  34. Coordinated activities of Myosin Vb isoforms and mTOR signaling regulate epithelial cell morphology during development.
  35. Identification of neurodegeneration indicators and disease progression in metachromatic leukodystrophy using quantitative NMR-based urinary metabolomics.
  36. The Pathogenic Sphingolipid Psychosine is Secreted in Extracellular Vesicles in the Brain of a Mouse Model of Krabbe Disease.
  37. Leucyl-tRNA synthetase is a tumour suppressor in breast cancer and regulates codon-dependent translation dynamics.
  38. Hunter Syndrome: The Phenotype of a Rare Storage Disease.
  39. TCA cycle off, ATF4 on for metabolic homeostasis.
  1. Cell Chem Biol. 2022 Mar 04. pii: S2451-9456(22)00087-3. [Epub ahead of print]
    Rheb regulates nuclear mTORC1 activity independent of farnesylation.
    Yanghao Zhong, Xin Zhou, Kun-Liang Guan, Jin Zhang.
      The small GTPase Ras homolog enriched in brain (Rheb) plays a critical role in activating the mechanistic target of rapamycin complex 1 (mTORC1), a signaling hub that regulates various cellular functions. We recently observed nuclear mTORC1 activity, raising an intriguing question as to how Rheb, which is known to be farnesylated and localized to intracellular membranes, regulates nuclear mTORC1. In this study, we found that active Rheb is present in the nucleus and required for nuclear mTORC1 activity. We showed that inhibition of farnesyltransferase reduced cytosolic, but not nuclear, mTORC1 activity. Furthermore, a farnesylation-deficient Rheb mutant, with preferential nuclear localization and specific lysosome tethering, enables nuclear and cytosolic mTORC1 activities, respectively. These data suggest that non-farnesylated Rheb is capable of interacting with and activating mTORC1, providing mechanistic insights into the molecular functioning of Rheb as well as regulation of the recently observed, active pool of nuclear mTORC1.
    Keywords:  Compartmentation; PTM; TSC; biosensor; lipid modification; mTOR; small GTPase
    DOI:  https://doi.org/10.1016/j.chembiol.2022.02.006
  2. Life Sci Alliance. 2022 Jun;pii: e202101169. [Epub ahead of print]5(6):
    Single serine on TSC2 exerts biased control over mTORC1 activation mediated by ERK1/2 but not Akt.
    Brittany L Dunkerly-Eyring, Shi Pan, Miguel Pinilla-Vera, Desirae McKoy, Sumita Mishra, Maria I Grajeda Martinez, Christian U Oeing, Mark J Ranek, David A Kass.
      Tuberous sclerosis complex-2 (TSC2) negatively regulates mammalian target of rapamycin complex 1 (mTORC1), and its activity is reduced by protein kinase B (Akt) and extracellular response kinase (ERK1/2) phosphorylation to activate mTORC1. Serine 1364 (human) on TSC2 bidirectionally modifies mTORC1 activation by pathological growth factors or hemodynamic stress but has no impact on resting activity. We now show this modification biases to ERK1/2 but not Akt-dependent TSC2-mTORC1 activation. Endothelin-1-stimulated mTORC1 requires ERK1/2 activation and is bidirectionally modified by phospho-mimetic (S1364E) or phospho-silenced (S1364A) mutations. However, mTORC1 activation by Akt-dependent stimuli (insulin or PDGF) is unaltered by S1364 modification. Thrombin stimulates both pathways, yet only the ERK1/2 component is modulated by S1364. S1364 also has negligible impact on mTORC1 regulation by energy or nutrient status. In vivo, diet-induced obesity, diabetes, and fatty liver couple to Akt activation and are also unaltered by TSC2 S1364 mutations. This contrasts to prior reports showing a marked impact of both on pathological pressure-stress. Thus, S1364 provides ERK1/2-selective mTORC1 control and a genetic means to modify pathological versus physiological mTOR stimuli.
    DOI:  https://doi.org/10.26508/lsa.202101169
  3. Autophagy. 2022 Mar 15.
    Follicular lymphoma-associated mutations in the V-ATPase chaperone VMA21 activate autophagy creating a targetable dependency.
    Fangyang Wang, Ying Yang, Gabriel Boudagh, Eeva-Liisa Eskelinen, Daniel J Klionsky, Sami N Malek.
      The discovery of recurrent mutations in subunits and regulators of the vacuolar-type H+-translocating ATPase (V-ATPase) in follicular lymphoma (FL) highlights a role for macroautophagy/autophagy, amino-acid, and nutrient-sensing pathways in the pathogenesis of this disease. Here, we report on novel mutations in the ER-resident chaperone VMA21, which is involved in V-ATPase assembly in 12% of FL. Mutations in a novel VMA21 hotspot (p.93X) result in the removal of a C-terminal non-canonical ER retrieval signal thus causing VMA21 mislocalization to lysosomes. The resulting impairment in V-ATPase function prevents full lysosomal acidification and function, including impaired pH-dependent protein degradation as shown via lysosomal metabolomics and ultimately causes a degree of amino acid depletion in the cytoplasm. These deficiencies result in compensatory autophagy activation, as measured using multiple complementary assays in human and yeast cells. Of translational significance, the compensatory activation of autophagy creates a dependency for survival for VMA21-mutated primary human FL as shown using inhibitors to ULK1, the proximal autophagy-regulating kinase. Using high-throughput microscopy-based screening assays for autophagy-inhibiting compounds, we identify multiple clinical grade cyclin-dependent kinase inhibitors as promising drugs and thus provide new rationale for innovative clinical trials in FL harboring aberrant V-ATPase.
    Keywords:  Follicular lymphoma; VMA21 mutations; autophagy; lysosomal dysfunction; survival
    DOI:  https://doi.org/10.1080/15548627.2022.2050663
  4. Autophagy. 2022 Mar 15.
    Recombinant pro-CTSD (cathepsin D) enhances SNCA/α-Synuclein degradation in α-Synucleinopathy models.
    Susy Prieto Huarcaya, Alice Drobny, André R A Marques, Alessandro Di Spiezio, Jan Philipp Dobert, Denise Balta, Christian Werner, Tania Rizo, Lisa Gallwitz, Simon Bub, Iva Stojkovska, Nandkishore R Belur, Jens Fogh, Joseph R Mazzulli, Wei Xiang, Amitkumar Fulzele, Mario Dejung, Markus Sauer, Beate Winner, Stefan Rose-John, Philipp Arnold, Paul Saftig, Friederike Zunke.
      Parkinson disease (PD) is a neurodegenerative disorder characterized by the abnormal intracellular accumulation of SNCA/α-synuclein. While the exact mechanisms underlying SNCA pathology are not fully understood, increasing evidence suggests the involvement of autophagic as well as lysosomal deficiencies. Because CTSD (cathepsin D) has been proposed to be the major lysosomal protease involved in SNCA degradation, its deficiency has been linked to the presence of insoluble SNCA conformers in the brain of mice and humans as well as to the transcellular transmission of SNCA aggregates. We here postulate that SNCA degradation can be enhanced by the application of the recombinant human proform of CTSD (rHsCTSD). Our results reveal that rHsCTSD is efficiently endocytosed by neuronal cells, correctly targeted to lysosomes and matured to an enzymatically active protease. In dopaminergic neurons derived from induced pluripotent stem cells (iPSC) of PD patients harboring the A53T mutation within the SNCA gene, we confirm the reduction of insoluble SNCA after treatment with rHsCTSD. Moreover, we demonstrate a decrease of pathological SNCA conformers in the brain and within primary neurons of a CTSD-deficient mouse model after dosing with rHsCTSD. Boosting lysosomal CTSD activity not only enhanced SNCA clearance, but also restored endo-lysosome and autophagy function in human and murine neurons as well as tissue. Our findings indicate that CTSD is critical for SNCA clearance and function. Thus, enzyme replacement strategies utilizing CTSD may also be of therapeutic interest for the treatment of PD and other synucleinopathies aiming to decrease the SNCA burden.
    Keywords:  Parkinson disease; cathepsin D; lysosomal degradation; lysosomal storage disorders; synucleinopathies; α-synuclein
    DOI:  https://doi.org/10.1080/15548627.2022.2045534
  5. Oncogene. 2022 Mar 12.
    eIF3a regulation of mTOR signaling and translational control via HuR in cellular response to DNA damage.
    Shijie Ma, Zizheng Dong, Yanfei Huang, Jing-Yuan Liu, Jian-Ting Zhang.
      eIF3a (eukaryotic translation initiation factor 3a), a subunit of the eIF3 complex, has been suggested to play a regulatory role in protein synthesis and in cellular response to DNA-damaging treatments. S6K1 is an effector and a mediator of mTOR complex 1 (mTORC1) in regulating protein synthesis and integrating diverse signals into control of cell growth and response to stress. Here, we show that eIF3a regulates S6K1 activity by inhibiting mTORC1 kinase via regulating Raptor synthesis. The regulation of Raptor synthesis is via eIF3a interaction with HuR (human antigen R) and binding of the eIF3a-HuR complex to the 5'-UTR of Raptor mRNA. Furthermore, mTORC1 may mediate eIF3a function in cellular response to cisplatin by regulating synthesis of NER proteins and NER activity. Taken together, we conclude that the mTOR signaling pathway may also be regulated by translational control and mediate eIF3a regulation of cancer cell response to cisplatin by regulating NER protein synthesis.
    DOI:  https://doi.org/10.1038/s41388-022-02262-5
  6. Nat Commun. 2022 Mar 14. 13(1): 1300
    Lysosomal Ca2+-mediated TFEB activation modulates mitophagy and functional adaptation of pancreatic β-cells to metabolic stress.
    Kihyoun Park, Hyejin Lim, Jinyoung Kim, Yeseong Hwang, Yu Seol Lee, Soo Han Bae, Hyeongseok Kim, Hail Kim, Shin-Wook Kang, Joo Young Kim, Myung-Shik Lee.
      Although autophagy is critical for pancreatic β-cell function, the role and mechanism of mitophagy in β-cells are unclear. We studied the role of lysosomal Ca2+ in TFEB activation by mitochondrial or metabolic stress and that of TFEB-mediated mitophagy in β-cell function. Mitochondrial or metabolic stress induced mitophagy through lysosomal Ca2+ release, increased cytosolic Ca2+ and TFEB activation. Lysosomal Ca2+ replenishment by ER- > lysosome Ca2+ refilling was essential for mitophagy. β-cell-specific Tfeb knockout (TfebΔβ-cell) abrogated high-fat diet (HFD)-induced mitophagy, accompanied by increased ROS and reduced mitochondrial cytochrome c oxidase activity or O2 consumption. TfebΔβ-cell mice showed aggravation of HFD-induced glucose intolerance and impaired insulin release. Metabolic or mitochondrial stress induced TFEB-dependent expression of mitophagy receptors including Ndp52 and Optn, contributing to the increased mitophagy. These results suggest crucial roles of lysosomal Ca2+ release coupled with ER- > lysosome Ca2+ refilling and TFEB activation in mitophagy and maintenance of pancreatic β-cell function during metabolic stress.
    DOI:  https://doi.org/10.1038/s41467-022-28874-9
  7. Front Mol Biosci. 2022 ;9 874267
    Editorial: Molecular Aspects of Mucopolysaccharidoses.
    Grzegorz Węgrzyn, Karolina Pierzynowska, Luigi Michele Pavone.
      
    Keywords:  genetic variations; genotype-phenotype correlation; glycosaminoglycans; lysosomal storage diseases; mucopolysaccharidoses
    DOI:  https://doi.org/10.3389/fmolb.2022.874267
  8. Mol Biol Cell. 2022 Mar 16. mbcE21120611
    Identification of defined structural elements within TOR2 kinase required for TOR Complex 2 assembly and function in S. cerevisiae.
    Jennifer Tsverov, Kristina Yegorov, Ted Powers.
      mTOR is a large protein kinase that assembles into two multi-subunit protein complexes, mTORC1 and mTORC2, to regulate cell growth in eukaryotic cells. While significant progress has been made in our understanding of the composition and structure of these complexes, important questions remain regarding the role of specific sequences within mTOR important for complex formation and activity. To address these issues, we have used a molecular genetic approach to explore TOR Complex assembly in budding yeast, where two closely related TOR paralogs, TOR1 and TOR2, partition preferentially into TORC1 versus TORC2, respectively. We previously identified a ∼500 amino acid segment within the N-terminal half of each protein, termed the Major Assembly Specificity (MAS) Domain, which can govern specificity in formation of each complex. In this study, we have extended the use of chimeric TOR1-TOR2 genes as a "sensitized" genetic system to identify specific subdomains rendered essential for TORC2 function, using synthetic lethal interaction analyses. Our findings reveal important design principles underlying the dimeric assembly of TORC2, as well as identify specific segments within the MAS domain critical for TORC2 function, to a level approaching single amino acid resolution. Together these findings highlight the complex and cooperative nature of TOR Complex assembly and function.
    DOI:  https://doi.org/10.1091/mbc.E21-12-0611
  9. FEBS J. 2022 Mar 14.
    Regulation of basal autophagy by calmodulin availability.
    Jennifer Giles, Vanessa Lopez, Elizabeth McConnaha, Matthew Hayden, Caleb Kragenbring, David Carli, Eric Wauson, Quang-Kim Tran.
      Macroautophagy (hereafter autophagy) is a process that degrades cellular components to maintain homeostasis. The Ca2+ sensor calmodulin (CaM) regulates numerous cell functions but is a limiting factor due to its insufficient availability for all target proteins. However, evidence that CaM availability regulates basal autophagy is lacking. Here, we have tested this hypothesis. CaM antagonists W-7, trifluoperazine and CGS9343b cause autophagosome accumulation and inhibit basal autophagic flux in the same manner as does chloroquine. These reagents promote the activity of AMP-activated protein kinase (AMPK) but not that of the mechanistic target of rapamycin (mTOR). Competitive binding assays using CaM sensors with different Ca2+ dependencies showed that chloroquine directly binds CaM in a Ca2+ -dependent fashion. The CaM antagonists have disparate effects on cytoplasmic Ca2+ , triggering from none to robust signals, indicating that their consistent inhibition of autophagy is due to inhibition of CaM and not Ca2+ . Chelating intracellular Ca2+ reduces the effect of the CaM antagonists to accumulate LC3-II, indicating that they do so by inhibiting CaM-dependent activities at basal Ca2+ level. The CaM antagonists cause lysosomal alkalinisation. Consistently, buffering CaM with a high-affinity CaM-binding protein that binds CaM at resting Ca2+ level increases lysosomal pH. Enhanced CaM buffering using a chimeric protein that contains two high-affinity CaM-binding sites that can collectively bind CaM at a large range of Ca2+ further increases lysosomal pH and increases LC3-II accumulation and AMPK activity, but not that of mTOR. These data demonstrate that CaM availability is required for basal autophagy.
    Keywords:  autophagy; calmodulin; calmodulin antagonists; chloroquine; lysosomal acidification
    DOI:  https://doi.org/10.1111/febs.16432
  10. Cell Calcium. 2022 Feb 28. pii: S0143-4160(22)00040-9. [Epub ahead of print]104 102565
    Endolysosomal calcium release and cardiac physiology.
    Derek A Terrar.
      Calcium ions play a central role in determining the timing and magnitude of the pumping action of heart muscle in a process which couples electrical activity of action potentials to muscle contraction. Regulation of this excitation-contraction coupling is achieved by Ca2+ signalling mechanisms that include activation of Ca2+ mobilising agents which influence the movement of Ca2+ between intracellular membrane-bound compartments. Research discussed here concerns endolysosomes, which play diverse signalling roles throughout the body. In the heart, a population of endolysosomes is strategically placed close to two other important membrane bound organelles, sarcoplasmic reticulum (SR) and mitochondria. In each case this proximity provides a structural basis for highly localised Ca2+ signalling in nanodomains between endolysosomes and the organelle. Ca2+ is released from endolysosomes via at least two varieties of two-pore domain channels (TPCs) in mammalian cardiac cells, TPC1 determining the interaction with mitochondria, while TPC2 controls the influence on SR. Ca2+ release via both TPC1 and TPC2 is enhanced by the Ca2+ mobilising agent, nicotinic acid adenine dinucleotide phosphate (NAADP) which is synthesised in the heart primarily by CD38. In normal physiology, NAADP plays an important regulatory role in which Ca2+ is released from endolysosomes via TPC2 channels into a nanodomain next to SR, and an amplification mechanism resulting from Ca2+ activation of CaMKII enhances SR Ca2+ uptake by the enzyme SERCA to increase the amplitude of the Ca2+ transient accompanying action potentials. A separate mechanism underlies pathology associated with reperfusion after ischaemia, when NAADP-mediated endolysosomal calcium release via TPC1 acts on nearby mitochondria resulting in abnormal SR Ca2+ release and extreme disruption to the normal excitation-contraction coupling process, causing muscle damage. There are different roles for PKA in the two pathways dependant on TPC1 or TPC2. Oxidising conditions during reperfusion following ischaemia promote disulphide bond formation in PKAIalpha causing accumulation of PKAI holoenzyme in endolysosomes and cardioprotective inhibition of TPC1 channels. In the case of TPC2, PKAII actions are thought to enhance NAADP synthesis by CD38 therefore promoting the endolysosomal influence on SR Ca2+. Excessive activation of this pathway leads to cardiac arrhythmias and hypertrophy.
    Keywords:  CD38; Calcium Signaling; Cardiac Myocyte; Cardiac atria; Cardiac ventricle; Endolysosome; Heart; Lysosome; Mitochondria; NAADP; Sarcoplasmic Reticulum
    DOI:  https://doi.org/10.1016/j.ceca.2022.102565
  11. Cell Biochem Funct. 2022 Mar 14.
    Rab34 plays a critical role as a bidirectional regulator of osteoclastogenesis.
    Yunxia Feng, Manh Tien Tran, Yanyin Lu, Kaung Htike, Yuka Okusha, Chiharu Sogawa, Takanori Eguchi, Tomoko Kadowaki, Eiko Sakai, Takayuki Tsukuba, Kuniaki Okamoto.
      Accumulating evidence suggests that Rab GTPases representing the largest branch of Ras superfamily have recently emerged as the core factors for the regulation of osteoclastogenesis through modulating vesicular transport amongst specific subcellular compartments. Among these, Rab34 GTPase has been identified to be important for the post-Golgi secretory pathway and for phagocytosis; nevertheless, its specific role in osteoclastogenesis has been completely obscure. Here, upon the in vitro model of osteoclast formation derived from murine macrophages like RAW-D cells or bone marrow-derived macrophages, we reveal that Rab34 regulates osteoclastogenesis bidirectionally. More specifically, Rab34 serves as a negative regulator of osteoclast differentiation by promoting the lysosome-induced proteolysis of two osteoclastogenic surface receptors, c-fms and RANK, via the axis of early endosomes-late endosomes-lysosomes, leading to alleviate the transcriptional activity of two of the master regulator of osteoclast differentiation, c-fos and NFATc-1, eventually attenuating osteoclast differentiation and bone resorption. Besides, Rab34 plays a crucial role in modulating the secretory network of lysosome-related proteases including matrix metalloprotease 9 and Cathepsin K across the ruffled borders of osteoclasts, contributing to the regulation of bone resorption.
    Keywords:  NFATc-1; RANK; Rab34; c-fms; osteoclasts; vesicular transport
    DOI:  https://doi.org/10.1002/cbf.3691
  12. J Cell Biol. 2022 May 02. pii: e202112024. [Epub ahead of print]221(5):
    Material properties of phase-separated TFEB condensates regulate the autophagy-lysosome pathway.
    Zheng Wang, Di Chen, Dongshi Guan, Xiaobo Liang, Jianfeng Xue, Hongyu Zhao, Guangtao Song, Jizhong Lou, Yan He, Hong Zhang.
      Very little is known about how the material properties of protein condensates assembled via liquid-liquid phase separation (LLPS) are maintained and affect physiological functions. Here we show that liquid-like condensates of the transcription factor TFEB exhibit low fusion propensity in vitro and in living cells. We directly measured the attraction force between droplets, and we characterized the interfacial tension, viscosity, and elasticity of TFEB condensates. TFEB condensates contain rigid interfacial boundaries that govern their interaction behaviors. Several small molecules, including Ro-3306, modify the material properties of TFEB condensates, increasing their size and fusion propensity. These compounds promote lysosomal biogenesis and function in a TFEB-dependent manner without changing its cytoplasmic-nuclear translocation. Ro-3306 promotes autophagy activity, facilitating degradation of toxic protein aggregates. Our study helps explain how protein condensates are maintained as physically separate entities and reveals that the material properties of TFEB condensates can be harnessed to modulate TFEB activity.
    DOI:  https://doi.org/10.1083/jcb.202112024
  13. Heliyon. 2022 Mar;8(3): e09031
    Iduronate-2-sulfatase interactome: validation by yeast two-hybrid assay.
    Eliana Benincore-Flórez, Jorge El-Azaz, Gabriela Alejandra Solarte, Alexander Rodríguez, Luis H Reyes, Carlos Javier Alméciga-Díaz, Carolina Cardona-Ramírez.
      Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a rare X-linked recessive disease caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase (IDS), which activates intracellular accumulation of nonmetabolized glycosaminoglycans such as heparan sulfate and dermatan sulfate. This accumulation causes severe damage to several tissues, principally the central nervous system. Previously, we identified 187 IDS-protein interactions in the mouse brain. To validate a subset of these interactions, we selected and cloned the coding regions of 10 candidate genes to perform a targeted yeast two-hybrid assay. The results allowed the identification of the physical interaction of IDS with LSAMP and SYT1. Although the physiological relevance of these complexes is unknown, recent advances allow us to point out that these interactions could be involved in vesicular trafficking of IDS through the interaction with SYT1, as well as to the ability to form a transcytosis module between the cellular components of the blood-brain-barrier (BBB) through its interaction with LSAMP. These results may shed light on the role of IDS on cellular homeostasis and may also contribute to the understanding of MPS II physiopathology and the development of novel therapeutic strategies to transport recombinant IDS through the brain endothelial cells toward the brain parenchyma.
    Keywords:  Hunter syndrome; Interactome; Lysosome; Proteomics; Yeast two-hybrid
    DOI:  https://doi.org/10.1016/j.heliyon.2022.e09031
  14. Acta Neuropathol Commun. 2022 Mar 14. 10(1): 33
    TMEM106B deficiency impairs cerebellar myelination and synaptic integrity with Purkinje cell loss.
    Tuancheng Feng, Lin Luan, Isabel Iscol Katz, Mohammed Ullah, Vivianna M Van Deerlin, John Q Trojanowski, Edward B Lee, Fenghua Hu.
      TMEM106B, a type II lysosomal transmembrane protein, has recently been associated with brain aging, hypomyelinating leukodystrophy, frontotemporal lobar degeneration (FTLD) and several other brain disorders. TMEM106B is critical for proper lysosomal function and TMEM106B deficiency leads to myelination defects, FTLD related pathology, and motor coordination deficits in mice. However, the physiological and pathological functions of TMEM106B in the brain are still not well understood. In this study, we investigate the role of TMEM106B in the cerebellum, dysfunction of which has been associated with FTLD and other brain disorders. We found that TMEM106B is ubiquitously expressed in neurons in the cerebellum, with the highest levels in the Purkinje neurons. Aged TMEM106B-deficient mice show significant loss of Purkinje neurons specifically in the anterior lobe of the cerebellum. Increased microglia and astrocyte activation, as well as an accumulation of ubiquitinated proteins, p62 and TDP-43 were also detected in the cerebellum of aged TMEM106B deficient mice. In the young mice, myelination defects and a significant loss of synapses between Purkinje and deep cerebellar nuclei neurons were observed. Interestingly, TMEM106B deficiency causes distinct lysosomal phenotypes in different types of neurons and glia in the cerebellum and frontal cortex. In humans, TMEM106B rs1990622 risk allele (T/T) is associated with increased Purkinje neuron loss. Taken together, our studies support that TMEM106B regulates lysosomal function in a cell-type-specific manner and TMEM106B is critical for maintaining synaptic integrity and neural functions in the cerebellum.
    Keywords:  Cerebellum; FTLD; Lysosome; Myelination; TMEM106B
    DOI:  https://doi.org/10.1186/s40478-022-01334-7
  15. Mol Neurobiol. 2022 Mar 15.
    The Role of Zinc in Axon Formation via the mTORC1 Pathway.
    Seunghyuk Choi, Donghyeon Kang, Jieun Kang, Dae Ki Hong, Beom Seok Kang, A Ra Kho, Bo Young Choi, Sung-Oh Huh, Sang Won Suh.
      Zinc is an essential micronutrient required for proper function during neuronal development because it can modulate neuronal function and structure. A fully functional description of zinc in axonal processing in the central nervous system remains elusive. Here, we define the role of intracellular zinc in axon formation and elongation, involving the mammalian target of rapamycin complex 1 (mTORC1). To investigate the involvement of zinc in axon growth, we performed an ex vivo culture of mouse hippocampal neurons and administrated ZnCl2 as a media supplement. At 2 days in vitro, the administration of zinc induced the formation of multiple and elongated axons in the ex vivo culture system. A similar outcome was witnessed in callosal projection neurons in a developing mouse brain. Treatment with extracellular zinc activated the mTORC1 signaling pathway in mouse hippocampal neuronal cultures. The zinc-dependent enhancement of neuronal processing was inhibited either by the deactivation of mTORC1 with RAPTOR shRNA or by mTOR-insensitive 4EBP1 mutants. Additionally, zinc-dependent mTORC1 activation enhanced the axonal translation of TC10 and Par3 may be responsible for axonal growth. We identified a promising role of zinc in controlling axonogenesis in the developing brain, which, in turn, may indicate a novel structural role of zinc in the cytoskeleton and developing neurons.
    Keywords:  Axon; Primary neuron; Zinc; mTORC1
    DOI:  https://doi.org/10.1007/s12035-022-02785-8
  16. Mol Psychiatry. 2022 Mar 17.
    Autistic-like behavior and cerebellar dysfunction in Bmal1 mutant mice ameliorated by mTORC1 inhibition.
    Dong Liu, Carmen Nanclares, Konstanze Simbriger, Kun Fang, Ethan Lorsung, Nam Le, Inês Silva Amorim, Kleanthi Chalkiadaki, Salil Saurav Pathak, Jin Li, Jonathan C Gewirtz, Victor X Jin, Paulo Kofuji, Alfonso Araque, Harry T Orr, Christos G Gkogkas, Ruifeng Cao.
      Although circadian and sleep disorders are frequently associated with autism spectrum disorders (ASD), it remains elusive whether clock gene disruption can lead to autistic-like phenotypes in animals. The essential clock gene Bmal1 has been associated with human sociability and its missense mutations are identified in ASD. Here we report that global Bmal1 deletion led to significant social impairments, excessive stereotyped and repetitive behaviors, as well as motor learning disabilities in mice, all of which resemble core behavioral deficits in ASD. Furthermore, aberrant cell density and immature morphology of dendritic spines were identified in the cerebellar Purkinje cells (PCs) of Bmal1 knockout (KO) mice. Electrophysiological recordings uncovered enhanced excitatory and inhibitory synaptic transmission and reduced firing rates in the PCs of Bmal1 KO mice. Differential expression of ASD- and ataxia-associated genes (Ntng2, Mfrp, Nr4a2, Thbs1, Atxn1, and Atxn3) and dysregulated pathways of translational control, including hyperactivated mammalian target of rapamycin complex 1 (mTORC1) signaling, were identified in the cerebellum of Bmal1 KO mice. Interestingly, the antidiabetic drug metformin reversed mTORC1 hyperactivation and alleviated major behavioral and PC deficits in Bmal1 KO mice. Importantly, conditional Bmal1 deletion only in cerebellar PCs was sufficient to recapitulate autistic-like behavioral and cellular changes akin to those identified in Bmal1 KO mice. Together, these results unveil a previously unidentified role for Bmal1 disruption in cerebellar dysfunction and autistic-like behaviors. Our findings provide experimental evidence supporting a putative role for dysregulation of circadian clock gene expression in the pathogenesis of ASD.
    DOI:  https://doi.org/10.1038/s41380-022-01499-6
  17. EMBO Mol Med. 2022 Mar 17. e14297
    Autologous, lentivirus-modified, T-rapa cell "micropharmacies" for lysosomal storage disorders.
    Murtaza S Nagree, Tania C Felizardo, Mary L Faber, Jitka Rybova, C Anthony Rupar, S Ronan Foley, Maria Fuller, Daniel H Fowler, Jeffrey A Medin.
      T cells are the current choice for many cell therapy applications. They are relatively easy to access, expand in culture, and genetically modify. Rapamycin-conditioning ex vivo reprograms T cells, increasing their memory properties and capacity for survival, while reducing inflammatory potential and the amount of preparative conditioning required for engraftment. Rapamycin-conditioned T cells have been tested in patients and deemed to be safe to administer in numerous settings, with reduced occurrence of infusion-related adverse events. We demonstrate that ex vivo lentivirus-modified, rapamycin-conditioned CD4+ T cells can also act as next-generation cellular delivery vehicles-that is, "micropharmacies"-to disseminate corrective enzymes for multiple lysosomal storage disorders. We evaluated the therapeutic potential of this treatment platform for Fabry, Gaucher, Farber, and Pompe diseases in vitro and in vivo. For example, such micropharmacies expressing α-galactosidase A for treatment of Fabry disease were transplanted in mice where they provided functional enzyme in key affected tissues such as kidney and heart, facilitating clearance of pathogenic substrate after a single administration.
    Keywords:  T cells; gene therapy; lentivirus; lysosomal storage disorders
    DOI:  https://doi.org/10.15252/emmm.202114297
  18. EMBO J. 2022 Mar 14. e109365
    Airway secretory cell fate conversion via YAP-mTORC1-dependent essential amino acid metabolism.
    Hae Yon Jeon, Jinwook Choi, Lianne Kraaier, Young Hoon Kim, David Eisenbarth, Kijong Yi, Ju-Gyeong Kang, Jin Woo Kim, Hyo Sup Shim, Joo-Hyeon Lee, Dae-Sik Lim.
      Tissue homeostasis requires lineage fidelity of stem cells. Dysregulation of cell fate specification and differentiation leads to various diseases, yet the cellular and molecular mechanisms governing these processes remain elusive. We demonstrate that YAP/TAZ activation reprograms airway secretory cells, which subsequently lose their cellular identity and acquire squamous alveolar type 1 (AT1) fate in the lung. This cell fate conversion is mediated via distinctive transitional cell states of damage-associated transient progenitors (DATPs), recently shown to emerge during injury repair in mouse and human lungs. We further describe a YAP/TAZ signaling cascade to be integral for the fate conversion of secretory cells into AT1 fate, by modulating mTORC1/ATF4-mediated amino acid metabolism in vivo. Importantly, we observed aberrant activation of the YAP/TAZ-mTORC1-ATF4 axis in the altered airway epithelium of bronchiolitis obliterans syndrome, including substantial emergence of DATPs and AT1 cells with severe pulmonary fibrosis. Genetic and pharmacologic inhibition of mTORC1 activity suppresses lineage alteration and subepithelial fibrosis driven by YAP/TAZ activation, proposing a potential therapeutic target for human fibrotic lung diseases.
    Keywords:  Damage-Associated Transient Progenitors; Hippo-YAP signaling; essential amino acid metabolism; mTORC1-ATF4 axis; pulmonary fibrosis and bronchiolitis obliterans
    DOI:  https://doi.org/10.15252/embj.2021109365
  19. Transl Res. 2022 Mar 11. pii: S1931-5244(22)00047-0. [Epub ahead of print]
    Cell Type-Specific Mechanistic Target of Rapamycin-Dependent Distortion of Autophagy Pathways in Lupus Nephritis.
    Tiffany Caza, Chathura Wijewardena, Laith Al-Rabadi, Andras Perl.
      Pro-inflammatory immune system development, metabolomic defects, and deregulation of autophagy play interconnected roles in driving the pathogenesis of systemic lupus erythematosus (SLE). Lupus nephritis (LN) is a leading cause of morbidity and mortality in SLE. While the causes of SLE have not been clearly delineated, skewing of T and B cell differentiation, activation of antigen-presenting cells, production of antinuclear autoantibodies and pro-inflammatory cytokines are known to contribute to disease development. Underlying this process are defects in autophagy and mitophagy that cause the accumulation of oxidative stress-generating mitochondria which promote necrotic cell death. Autophagy is generally inhibited by the activation of the mammalian target of rapamycin (mTOR), a large protein kinase that underlies abnormal immune cell lineage specification in SLE. Importantly, several autophagy-regulating genes, including ATG5 and ATG7, as well as mitophagy-regulating HRES-1/Rab4A have been linked to lupus susceptibility and molecular pathogenesis. Moreover, genetically-driven mTOR activation has been associated with fulminant lupus nephritis. mTOR activation and diminished autophagy promote the expansion of pro-inflammatory Th17, Tfh and CD3+CD4-CD8- double-negative (DN) T cells at the expense of CD8+ effector memory T (EMT) cells and CD4+ regulatory T cells (Tregs). mTOR activation and aberrant autophagy also involve renal podocytes, mesangial cells, endothelial cells, and tubular epithelial cells that may compromise end-organ resistance in LN. Activation of mTOR complexes 1 (mTORC1) and 2 (mTORC2) has been identified as biomarkers of disease activation and predictors of disease flares and prognosis in SLE patients with and without LN. This review highlights recent advances in molecular pathogenesis of LN with a focus on immuno-metabolic checkpoints of autophagy and their roles in pathogenesis, prognosis and selection of targets for treatment in SLE.
    Keywords:  Autophagy; B cells; CD3(+)CD4(−)CD8(−) double-negative T cells; CD4(+) T cells; CD8(+) T cells; Rab4A; Treg; antinuclear antibodies; biomarkers; dendritic cells; endosome traffic; glomerulonephritis; interferon; lupus nephritis; lysosome; mTOR; macrophages; mechanistic target of rapamycin; metabolomics; mitochondrial dysfunction; mitophagy; netosis; plasma cells; rapamycin; sirolimus; systemic lupus erythematosus
    DOI:  https://doi.org/10.1016/j.trsl.2022.03.004
  20. Front Synaptic Neurosci. 2022 ;14 826098
    Synaptic Vesicle Recycling and the Endolysosomal System: A Reappraisal of Form and Function.
    Daniela Ivanova, Michael A Cousin.
      The endolysosomal system is present in all cell types. Within these cells, it performs a series of essential roles, such as trafficking and sorting of membrane cargo, intracellular signaling, control of metabolism and degradation. A specific compartment within central neurons, called the presynapse, mediates inter-neuronal communication via the fusion of neurotransmitter-containing synaptic vesicles (SVs). The localized recycling of SVs and their organization into functional pools is widely assumed to be a discrete mechanism, that only intersects with the endolysosomal system at specific points. However, evidence is emerging that molecules essential for endolysosomal function also have key roles within the SV life cycle, suggesting that they form a continuum rather than being isolated processes. In this review, we summarize the evidence for key endolysosomal molecules in SV recycling and propose an alternative model for membrane trafficking at the presynapse. This includes the hypotheses that endolysosomal intermediates represent specific functional SV pools, that sorting of cargo to SVs is mediated via the endolysosomal system and that manipulation of this process can result in both plastic changes to neurotransmitter release and pathophysiology via neurodegeneration.
    Keywords:  endocytosis; endosome; lysosome; presynapse; trafficking; vesicle
    DOI:  https://doi.org/10.3389/fnsyn.2022.826098
  21. Proc Natl Acad Sci U S A. 2022 Mar 22. 119(12): e2100670119
    Lysosomal inhibition sensitizes TMEM16A-expressing cancer cells to chemotherapy.
    Avani Vyas, Roberto Gomez-Casal, Silvia Cruz-Rangel, Hugo Villanueva, Andrew G Sikora, Pavithra Rajagopalan, Devraj Basu, Jonathan Pacheco, Gerald R V Hammond, Kirill Kiselyov, Umamaheswar Duvvuri.
      SignificanceCisplatin is the first line therapy for patients with head and neck cancer. However, resistance to cisplatin remains a major concern. High expression of the calcium-activated chloride channel TMEM16A in tumors portends poor survival in these patients, possibly because of drug resistance. Here, we show that TMEM16A drives the sequestration of cisplatin into lysosomes. Subsequently, cisplatin is expelled via the delivery of lysosomes to the cell surface. We show that TMEM16A enhances this process, thereby promoting cisplatin resistance. We also show that lysosomal inhibition synergizes with cisplatin to induce tumor cell death. Our data uncovers a new fundamental feature of both lysosomal physiology and cancer cell biology that can potentially impact the treatment of patients with head and neck cancer.
    Keywords:  MITF; TMEM16A; cisplatin; hydroxychloroquine; lysosomal flux
    DOI:  https://doi.org/10.1073/pnas.2100670119
  22. Front Cell Dev Biol. 2022 ;10 834408
    Pathways and Mechanisms of Cellular Cholesterol Efflux-Insight From Imaging.
    Alice Dupont Juhl, Daniel Wüstner.
      Cholesterol is an essential molecule in cellular membranes, but too much cholesterol can be toxic. Therefore, mammalian cells have developed complex mechanisms to remove excess cholesterol. In this review article, we discuss what is known about such efflux pathways including a discussion of reverse cholesterol transport and formation of high-density lipoprotein, the function of ABC transporters and other sterol efflux proteins, and we highlight their role in human diseases. Attention is paid to the biophysical principles governing efflux of sterols from cells. We also discuss recent evidence for cholesterol efflux by the release of exosomes, microvesicles, and migrasomes. The role of the endo-lysosomal network, lipophagy, and selected lysosomal transporters, such as Niemann Pick type C proteins in cholesterol export from cells is elucidated. Since oxysterols are important regulators of cellular cholesterol efflux, their formation, trafficking, and secretion are described briefly. In addition to discussing results obtained with traditional biochemical methods, focus is on studies that use established and novel bioimaging approaches to obtain insight into cholesterol efflux pathways, including fluorescence and electron microscopy, atomic force microscopy, X-ray tomography as well as mass spectrometry imaging.
    Keywords:  ABC transporter; HDL; LDL; apoprotein A1 (Apo A1); cholesterol; extracellular vesicles; niemann pick disease; oxysterol
    DOI:  https://doi.org/10.3389/fcell.2022.834408
  23. Sci Adv. 2022 Mar 18. 8(11): eabm7688
    Hematopoietic stem cells temporally transition to thrombopoietin dependence in the fetal liver.
    Yeojin Lee, Emily DiMaulo-Milk, Juliana Leslie, Lei Ding.
      Tissue stem cells temporally change intrinsic mechanisms to meet physiological demands. However, little is known whether and how stem cells rely on distinct extrinsic maintenance mechanisms over time. Here, we found that hematopoietic stem cells (HSCs) temporally transition to depend on thrombopoietin (TPO), a key extrinsic factor, from E16.5 onward in the developing liver. Deletion of Tpo reduced mTOR activity, induced differentiation gene expression, and preferentially depleted metabolically active HSCs. Ectopic activation of the JAK2 or MAPK pathway did not rescue HSCs in Tpo-/- mice. Enforced activation of the mTOR pathway by conditionally deleting Tsc1 significantly rescued HSCs and their gene expression in Tpo-/- mice. Lin28b intrinsically promoted mTOR activation in HSCs, and its expression diminished over time. Conditional deletion of Lin28b further reduced mTOR activity and strongly exacerbated HSC depletion in Tpo-/- mice. Therefore, HSCs temporally transition from intrinsic LIN28B-dependent to extrinsic TPO-dependent maintenance in the developing liver.
    DOI:  https://doi.org/10.1126/sciadv.abm7688
  24. Am J Physiol Cell Physiol. 2022 Mar 16.
    Early secretory pathway-resident Zn transporter proteins contribute to cellular sphingolipid metabolism through activation of sphingomyelin phosphodiesterase 1.
    Sachiko Ueda, Yuki Manabe, Naoya Kubo, Naho Morino, Hana Yuasa, Miku Shiotsu, Tokuji Tsuji, Tatsuya Sugawara, Taiho Kambe.
      Sphingomyelin phosphodiesterase 1 (SMPD1) converts sphingomyelin into ceramide and phosphocholine; hence, loss of SMPD1 function causes abnormal accumulation of sphingomyelin in lysosomes, which results in the lipid-storage disorder Niemann-Pick disease (types A and B). SMPD1 activity is dependent on zinc, which is coordinated at the active site of the enzyme, and although SMPD1 has been suggested to acquire zinc at the sites where the enzyme is localized, precisely how SMPD1 acquires zinc remains to be clarified. Here, we addressed this using a gene-disruption/re-expression strategy. Our results revealed that Zn transporter 5 (ZNT5)-ZNT6 heterodimers and ZNT7 homodimers, which localize in the compartments of the early secretory pathway, play essential roles in SMPD1 activation. Both ZNT complexes contribute to cellular sphingolipid metabolism by activating SMPD1 because cells lacking the functions of the two complexes exhibited a reduced ceramide to sphingomyelin content ratio in terms of their dominant molecular species and an increase in the sphingomyelin content in terms of three minor species. Moreover, mutant cells contained multilamellar body-like structures, indicative of membrane stacking and accumulation, in the cytoplasm. These findings provide novel insights into the molecular mechanism underlying the activation of SMPD1, a key enzyme in sphingolipid metabolism.
    Keywords:  Zn transporter (ZNT); enzyme activation; lysosome; sphingomyelin phosphodiesterase 1 (SMPD1); zinc
    DOI:  https://doi.org/10.1152/ajpcell.00020.2022
  25. Front Neurosci. 2022 ;16 846584
    Rapamycin Improved Retinal Function and Morphology in a Mouse Model of Retinal Degeneration.
    Meng Zhao, Houting Lv, Na Yang, Guang-Hua Peng.
      The retina is an important visual organ, which is responsible for receiving light signals and transmitting them to the optic nerve center step by step. The retina contains a variety of cells, among which photoreceptor cells receive light signals and convert them into nerve signals, and are mainly responsible for light and dark vision. Retinal degeneration is mainly the degeneration of photoreceptor cells, and retinitis pigmentosa (RP) is characterized by rod degeneration followed by cone degeneration. So far, there is still a lack of effective drugs to treat RP. Here, we established a stable RP model by tail vein injection of methyl methanesulfonate to study the mechanism of retinal photoreceptor degeneration. Mechanistic target of rapamycin (mTOR) is located in the central pathway of growth and energy metabolism and changes in a variety of diseases in response to pathological changes. We found that the mTOR was activated in this model. Therefore, the inhibitor of mTOR, rapamycin was used to suppress the expression of mTOR and interfere with photoreceptor degeneration. Electroretinogram assay showed that the function of mice retina was improved. Hematoxylin and eosin staining results displayed that retinal photoreceptor thickness and morphology were improved. Also, the autophagy in rapamycin group was activated, which revealed that rapamycin may protect the retinal photoreceptor by inhibiting mTOR and then activating autophagy.
    Keywords:  MTOR; autophagy; photoreceptor; rapamycin; retinal degeneration
    DOI:  https://doi.org/10.3389/fnins.2022.846584
  26. Front Cell Dev Biol. 2022 ;10 852021
    Touch and Go: Membrane Contact Sites Between Lipid Droplets and Other Organelles.
    Pin-Chao Liao, Emily J Yang, Taylor Borgman, Istvan R Boldogh, Cierra N Sing, Theresa C Swayne, Liza A Pon.
      Lipid droplets (LDs) have emerged not just as storage sites for lipids but as central regulators of metabolism and organelle quality control. These critical functions are achieved, in part, at membrane contact sites (MCS) between LDs and other organelles. MCS are sites of transfer of cellular constituents to or from LDs for energy mobilization in response to nutrient limitations, as well as LD biogenesis, expansion and autophagy. Here, we describe recent findings on the mechanisms underlying the formation and function of MCS between LDs and mitochondria, ER and lysosomes/vacuoles and the role of the cytoskeleton in promoting LD MCS through its function in LD movement and distribution in response to environmental cues.
    Keywords:  cytoskeleton; endoplasmic reticulum; lipid droplets; lipophagy; lysosome; membrane contact sites; mitochondria; vacuole
    DOI:  https://doi.org/10.3389/fcell.2022.852021
  27. EMBO J. 2022 Mar 14. e110057
    The needs of a synapse-How local organelles serve synaptic proteostasis.
    Katarzyna M Grochowska, Maria Andres-Alonso, Anna Karpova, Michael R Kreutz.
      Synaptic function crucially relies on the constant supply and removal of neuronal membranes. The morphological complexity of neurons poses a significant challenge for neuronal protein transport since the machineries for protein synthesis and degradation are mainly localized in the cell soma. In response to this unique challenge, local micro-secretory systems have evolved that are adapted to the requirements of neuronal membrane protein proteostasis. However, our knowledge of how neuronal proteins are synthesized, trafficked to membranes, and eventually replaced and degraded remains scarce. Here, we review recent insights into membrane trafficking at synaptic sites and into the contribution of local organelles and micro-secretory pathways to synaptic function. We describe the role of endoplasmic reticulum specializations in neurons, Golgi-related organelles, and protein complexes like retromer in the synthesis and trafficking of synaptic transmembrane proteins. We discuss the contribution of autophagy and of proteasome-mediated and endo-lysosomal degradation to presynaptic proteostasis and synaptic function, as well as nondegradative roles of autophagosomes and lysosomes in signaling and synapse remodeling. We conclude that the complexity of neuronal cyto-architecture necessitates long-distance protein transport that combines degradation with signaling functions.
    Keywords:  Golgi satellites; autophagy; lysosomes; secretory trafficking
    DOI:  https://doi.org/10.15252/embj.2021110057
  28. Cureus. 2022 Feb;14(2): e21955
    Niemann-Pick Disease Type A: A Rare Disease With a Fatal Outcome.
    Khadija Qureshi, Zahraa Ghasan Abdulmajeed, Shoaib Saleem, Javera Tariq, Mashhood Iqbal.
      Niemann-Pick disease (NPD) type A is a fatal autosomal recessive lysosomal storage disorder. This rare condition impairs the metabolization of lipids, leading to their accumulation within the cells. Consequently, it causes growth retardation, pancytopenia, and cellular malfunctioning in various organ systems, including ocular, hepatic, pulmonary, brain, and neuronal tissues. Although rare, these patients present in both emergency and outpatient settings. Here, we report the case of a seven-month-old male infant who presented to the emergency department with continuous fever for one week, poor feeding, and failure to thrive. After a thorough history, examination, and laboratory workup, NPD type A was diagnosed. The patient received symptomatic therapy with the continuation of conservative management. In addition, the parents received detailed counseling regarding the genetics, progressive disease course, and prognosis of this condition.
    Keywords:  foamy histiocytes; lysosomal storage disorder; niemann-pick type a; pancytopenia; rare autosomal recessive disorder
    DOI:  https://doi.org/10.7759/cureus.21955
  29. Int J Oncol. 2022 Apr;pii: 47. [Epub ahead of print]60(4):
    Spine‑specific downregulation of LAPTM5 expression promotes the progression and spinal metastasis of estrogen receptor‑positive breast cancer by activating glutamine‑dependent mTOR signaling.
    Qingbing Meng, Lei Zhou, Haifeng Liang, Annan Hu, Hao Zhou, Jian Zhou, Xiaogang Zhou, Hong Lin, Xilei Li, Libo Jiang, Jian Dong.
      Estrogen receptor‑positive (ER+) breast cancer (BC) is a malignancy that is prone to metastasis to the spine, which is difficult to treat and often results in poor prognosis. However, the mechanism underlying the tumorigenesis and spinal metastasis of ER+ BC remains unclear. Lysosomal protein transmembrane 5 (LAPTM5) has been reported as a tumor suppressor in several types of cancer, but its role in ER+ BC has not been described. Here, by analyzing a gene sequencing dataset and ER+ BC tissues, tumor‑adjacent normal tissues and spinal metastatic tissues from patients and mouse models, we found that LAPTM5 expression is negatively related to the progression and spinal metastasis of ER+ BC. Subsequently, in vitro experiments demonstrated that downregulation of LAPTM5 expression promoted the proliferation, migration, and chemoresistance of ER+ BC cells by activating glutamine‑dependent mTOR signaling. A high level of CX3CL1 could inhibit LAPTM5 expression, explaining how ER+ BC metastasized to the spine. Thus, we found that LAPTM5 functions as a tumor suppressor in ER+ BC and that the CX3CL/CX3CR1/LAPTM5/glutamine axis mediates the spinal metastasis of ER+ BC. This axis may be a promising therapeutic target for ER+ BC.
    Keywords:  CX3CL1/CX3CR1; LAPTM5; estrogen receptor‑positive breast cancer; glutamine; mTOR; spinal metastasis
    DOI:  https://doi.org/10.3892/ijo.2022.5337
  30. Biomed Pharmacother. 2022 Mar 12. pii: S0753-3322(22)00196-2. [Epub ahead of print]149 112808
    A novel brain-penetrant oral UGT8 inhibitor decreases in vivo galactosphingolipid biosynthesis in murine Krabbe disease.
    Eva Zaccariotto, María Begoña Cachón-González, Bing Wang, Sungtaek Lim, Bradford Hirth, Hyejung Park, Malika Fezoui, S Pablo Sardi, Paul Mason, Robert H Barker, Timothy M Cox.
      Krabbe disease is a rare, inherited neurodegenerative disease due to impaired lysosomal β-galactosylceramidase (GALC) activity and formation of neurotoxic β-galactosylsphingosine ('psychosine'). We investigated substrate reduction therapy with a novel brain-penetrant inhibitor of galactosylceramide biosynthesis, RA 5557, in twitcher mice that lack GALC activity and model Krabbe disease. This thienopyridine derivative selectively inhibits uridine diphosphate-galactose glycosyltransferase 8 (UGT8), the final step in the generation of galactosylceramides which are precursors of sulphatide and, in the pathological lysosome, the immediate source of psychosine. Administration of RA 5557, reduced pathologically elevated psychosine concentrations (72-86%) in the midbrain and cerebral cortex in twitcher mice: the inhibitor decreased galactosylceramides by about 70% in midbrain and cerebral cortex in mutant and wild type animals. Exposure to the inhibitor significantly decreased several characteristic inflammatory response markers without causing apparent toxicity to myelin-producing cells in wild type and mutant mice; transcript abundance of oligodendrocyte markers MBP (myelin basic protein) and murine UGT8 was unchanged. Administration of the inhibitor before conception and during several breeding cycles to mice did not impair fertility and gave rise to healthy offspring. Nevertheless, given the unchanged lifespan, it appears that GALC has critical functions in the nervous system beyond the hydrolysis of galactosylceramide and galactosylsphingosine. Our findings support further therapeutic exploration of orally active UGT8 inhibitors in Krabbe disease and related galactosphingolipid disorders. The potent thienopyridine derivative with effective target engagement here studied appears to have an acceptable safety profile in vivo; judicious dose optimization will be needed to ensure efficacious clinical translation.
    Keywords:  Krabbe disease; Psychosine; Substrate reduction therapy; Thienopyridine derivative; UGT8
    DOI:  https://doi.org/10.1016/j.biopha.2022.112808
  31. Biosci Biotechnol Biochem. 2022 Mar 15. pii: zbac041. [Epub ahead of print]
    A vacuolar membrane protein Vsb1p contributes to the vacuolar compartmentalization of basic amino acids in Schizosaccharomyces pombe.
    Shota Ohnishi, Miyuki Kawano-Kawada, Yusuke Yamamoto, Koichi Akiyama, Takayuki Sekito.
      Accumulation levels of Arg, Lys, and His in vacuoles of Schizosaccharomyces pombe cells were drastically decreased by the disruption of spac24h6.11c+ (vsb1+) gene identified by a homology search with the VSB1 gene of Saccharomyces cerevisiae. The Vsb1p fused with green fluorescent protein particularly localized at vacuolar membranes in S. pombe cells. Overexpression of vsb1+ markedly increased vacuolar levels of basic amino acids; however, overexpression of the vsb1D174A mutant did not affect the levels of these amino acids. These results suggest that the vsb1+ contributes to the accumulation of basic amino acids into the vacuoles of S. pombe and the aspartate residue in the putative 1st transmembrane domain conserved among fungal homologs is crucial for the function of Vsb1p.
    Keywords:  basic amino acids; compartmentalization; fission yeast; vacuole
    DOI:  https://doi.org/10.1093/bbb/zbac041
  32. Front Neurol. 2022 ;13 845877
    Neurophysiological Findings in Neuronal Ceroid Lipofuscinoses.
    Marina Trivisano, Alessandro Ferretti, Costanza Calabrese, Nicola Pietrafusa, Ludovica Piscitello, Giusy Carfi' Pavia, Federico Vigevano, Nicola Specchio.
      Neuronal ceroid lipofuscinoses (NCLs) are a heterogeneous group of neurodegenerative diseases, characterized by progressive cerebral atrophy due to lysosomal storage disorder. Common clinical features include epileptic seizures, progressive cognitive and motor decline, and visual failure, which occur over different time courses according to subtypes. During the latest years, many advances have been done in the field of targeted treatments, and in the next future, gene therapies and enzyme replacement treatments may be available for several NCL variants. Considering that there is rapid disease progression in NCLs, an early diagnosis is crucial, and neurophysiological features might have a key role for this purpose. Across the different subtypes of NCLs, electroencephalogram (EEG) is characterized by a progressive deterioration of cerebral activity with slowing of background activity and disappearance of spindles during sleep. Some types of heterogeneous abnormalities, diffuse or focal, prevalent over temporal and occipital regions, are described in many NCL variants. Photoparoxysmal response to low-frequency intermittent photic stimulation (IPS) is a typical EEG finding, mostly described in CLN2, CLN5, and CLN6 diseases. Visual evoked potentials (VEPs) allow to monitor the visual functions, and the lack of response at electroretinogram (ERG) reflects retinal neurodegeneration. Taken together, EEG, VEPs, and ERG may represent essential tools toward an early diagnosis of NCLs.
    Keywords:  EEG; electroretinogram; intermittent photic stimulation; neuronal ceroid lipofuscinoses; neurophysiological findings; photoparoxysmal response; visual evoked potentials
    DOI:  https://doi.org/10.3389/fneur.2022.845877
  33. Redox Biol. 2022 Mar 08. pii: S2213-2317(22)00052-0. [Epub ahead of print]51 102280
    Theranostic F-SLOH mitigates Alzheimer's disease pathology involving TFEB and ameliorates cognitive functions in Alzheimer's disease models.
    Ashok Iyaswamy, Xueli Wang, Senthilkumar Krishnamoorthi, Venkatapathy Kaliamoorthy, Sravan G Sreenivasmurthy, Siva Sundara Kumar Durairajan, Ju-Xian Song, Benjamin Chun-Kit Tong, Zhou Zhu, Cheng-Fu Su, Jia Liu, King-Ho Cheung, Jia-Hong Lu, Jie-Qiong Tan, Hung Wing Li, Man Shing Wong, Min Li.
      Accumulation of amyloid-β (Aβ) oligomers and phosphorylated Tau aggregates are crucial pathological events or factors that cause progressive neuronal loss, and cognitive impairments in Alzheimer's disease (AD). Current medications for AD have failed to halt, much less reverse this neurodegenerative disorder; therefore, there is an urgent need for the development of effective and safe drugs for AD therapy. In the present study, the in vivo therapeutic efficacy of an Aβ-oligomer-targeted fluorescent probe, F-SLOH, was extensively investigated in 5XFAD and 3XTg-AD mouse models. We have shown that F-SLOH exhibits an efficient inhibitory activity against Aβ aggregation in vivo, and acts as an effective theranostic agent for the treatment of multiple neuropathological changes in AD mouse models. F-SLOH has been found to significantly reduce not only the levels of Aβ oligomers, Tau aggregates and plaques but also the levels of amyloid precursor protein (APP) and its metabolites via autophagy lysosomal degradation pathway (ALP) in the brains of 5XFAD and 3XTg-AD mice. It also reduces astrocyte activation and microgliosis ultimately alleviating neuro-inflammation. Furthermore, F-SLOH mitigates hyperphosphorylated Tau aggregates, synaptic deficits and ameliorates synaptic memory function, and cognitive impairment in AD mouse models. The mechanistic studies have shown that F-SLOH promotes the clearance of C-terminal fragment 15 (CTF15) of APP and Paired helical filaments of Tau (PHF1) in stable cell models via the activation of transcription factor EB (TFEB). Moreover, F-SLOH promotes ALP and lysosomal biogenesis for the clearance of soluble, insoluble Aβ, and phospho Tau. Our results unambiguously reveal effective etiological capabilities of theranostic F-SLOH to target and intervene multiple neuropathological changes in AD mouse models. Therefore, F-SLOH demonstrates tremendous therapeutic potential for treating AD in its early stage.
    Keywords:  3XTg-AD; 5XFAD; Alzheimer's disease; Aβ-aggregate inhibition; Aβ-targeting; Theranostic
    DOI:  https://doi.org/10.1016/j.redox.2022.102280
  34. Development. 2022 Mar 15. pii: dev199363. [Epub ahead of print]149(6):
    Coordinated activities of Myosin Vb isoforms and mTOR signaling regulate epithelial cell morphology during development.
    Kirti Gupta, Sudipta Mukherjee, Sumit Sen, Mahendra Sonawane.
      The maintenance of epithelial architecture necessitates tight regulation of cell size and shape. However, mechanisms underlying epithelial cell size regulation remain poorly understood. We show that the interaction of Myosin Vb with Rab11 prevents the accumulation of apically derived endosomes to maintain cell-size, whereas that with Rab10 regulates vesicular transport from the trans-Golgi. These interactions are required for the fine-tuning of the epithelial cell morphology during zebrafish development. Furthermore, the compensatory cell growth upon cell-proliferation inhibition involves a preferential expansion of the apical domain, leading to flatter epithelial cells, an efficient strategy to cover the surface with fewer cells. This apical domain growth requires post-trans-Golgi transport mediated by the Rab10-interacting Myosin Vb isoform, downstream of the mTOR-Fatty Acid Synthase (FASN) axis. Changes in trans-Golgi morphology indicate that the Golgi synchronizes mTOR-FASN-regulated biosynthetic input and Myosin Vb-Rab10 dependent output. Our study unravels the mechanism of polarized growth in epithelial cells and delineates functions of Myosin Vb isoforms in cell size regulation during development.
    Keywords:  Cell size regulation; Compensatory cell growth; Epidermis; Myosin Vb; Tissue homeostasis; Zebrafish; mTOR signaling
    DOI:  https://doi.org/10.1242/dev.199363
  35. JIMD Rep. 2022 Mar;63(2): 168-180
    Identification of neurodegeneration indicators and disease progression in metachromatic leukodystrophy using quantitative NMR-based urinary metabolomics.
    Lucia Laugwitz, Laimdota Zizmare, Vidiyaah Santhanakumaran, Claire Cannet, Judith Böhringer, Jürgen G Okun, Manfred Spraul, Ingeborg Krägeloh-Mann, Samuel Groeschel, Christoph Trautwein.
      Metachromatic leukodystrophy (MLD) is a lysosomal storage disease caused by a deficiency of the arylsulfatase A (ARSA). ARSA deficiency leads to an accumulation of sulfatides primarily in the nervous system ultimately causing demyelination. With evolving therapeutic options, there is an increasing need for indicators to evaluate disease progression. Here, we report targeted metabolic urine profiling of 56 MLD patients including longitudinal sampling, using 1H (proton) nuclear magnetic resonance (NMR) spectroscopy. 1H-NMR urine spectra of 119 MLD samples and 323 healthy controls were analyzed by an in vitro diagnostics research (IVDr) tool, covering up to 50 endogenous and 100 disease-related metabolites on a 600-MHz IVDr NMR spectrometer. Quantitative data reports were analyzed regarding age of onset, clinical course, and therapeutic intervention. The NMR data reveal metabolome changes consistent with a multiorgan affection in MLD patients in comparison to controls. In the MLD cohort, N-acetylaspartate (NAA) excretion in urine is elevated. Early onset MLD forms show a different metabolic profile suggesting a metabolic shift toward ketogenesis in comparison to late onset MLD and controls. In samples of juvenile MLD patients who stabilize clinically after hematopoietic stem cell transplantation (HSCT), the macrophage activation marker neopterin is elevated. We were able to identify different metabolic patterns reflecting variable organ disturbances in MLD, including brain and energy metabolism and inflammatory processes. We suggest NAA in urine as a quantitative biomarker for neurodegeneration. Intriguingly, elevated neopterin after HSCT supports the hypothesis that competent donor macrophages are crucial for favorable outcome.
    Keywords:  N‐acetylaspartate; arylsulfatase A; metachromatic leukodystrophy; neopterin; nuclear magnetic resonance; urine metabolomics
    DOI:  https://doi.org/10.1002/jmd2.12273
  36. ASN Neuro. 2022 Jan-Dec;14:14 17590914221087817
    The Pathogenic Sphingolipid Psychosine is Secreted in Extracellular Vesicles in the Brain of a Mouse Model of Krabbe Disease.
    Cory R Reiter, Rima Rebiai, Angelika Kwak, Jeff Marshall, Dylan Wozniak, Giusepe Scesa, Duc Nguyen, Emily Rue, Chandimal Pathmasiri, Robert Pijewski, Richard van Breemen, Stephanie Cologna, Stephen J Crocker, M Irene Givogri, Ernesto R Bongarzone.
      Psychosine exerts most of its toxic effects by altering membrane dynamics with increased shedding of extracellular vesicles (EVs). In this study, we discovered that a fraction of psychosine produced in the brain of the Twitcher mouse, a model for Krabbe disease, is associated with secreted EVs. We evaluated the effects of attenuating EV secretion in the Twitcher brain by depleting ceramide production with an inhibitor of neutral sphingomyelinase 2, GW4869. Twitcher mice treated with GW4869 had decreased overall EV levels, reduced EV-associated psychosine and unexpectedly, correlated with increased disease severity. Notably, characterization of well-established, neuroanatomic hallmarks of disease pathology, such as demyelination and inflammatory gliosis, remained essentially unaltered in the brains of GW4869-treated Twitcher mice compared to vehicle-treated Twitcher controls. Further analysis of Twitcher brain pathophysiology is required to understand the mechanism behind early-onset disease severity in GW4869-treated mice. The results herein demonstrate that some pathogenic lipids like psychosine may be secreted using EV pathways. Our results highlight the relevance of this secretory mechanism as a possible contributor to spreading pathogenic lipids in neurological lipidoses.
    Keywords:  demyelination; exosomes; extracellular vesicles; lysosomes; neurotoxicity; psychosine
    DOI:  https://doi.org/10.1177/17590914221087817
  37. Nat Cell Biol. 2022 Mar;24(3): 307-315
    Leucyl-tRNA synthetase is a tumour suppressor in breast cancer and regulates codon-dependent translation dynamics.
    Maria C Passarelli, Alexandra M Pinzaru, Hosseinali Asgharian, Maria V Liberti, Søren Heissel, Henrik Molina, Hani Goodarzi, Sohail F Tavazoie.
      Tumourigenesis and cancer progression require enhanced global protein translation1-3. Such enhanced translation is caused by oncogenic and tumour-suppressive events that drive the synthesis and activity of translational machinery4,5. Here we report the surprising observation that leucyl-tRNA synthetase (LARS) becomes repressed during mammary cell transformation and in human breast cancer. Monoallelic genetic deletion of LARS in mouse mammary glands enhanced breast cancer tumour formation and proliferation. LARS repression reduced the abundance of select leucine tRNA isoacceptors, leading to impaired leucine codon-dependent translation of growth suppressive genes, including epithelial membrane protein 3 (EMP3) and gamma-glutamyltransferase 5 (GGT5). Our findings uncover a tumour-suppressive tRNA synthetase and reveal that dynamic repression of a specific tRNA synthetase-along with its downstream cognate tRNAs-elicits a downstream codon-biased translational gene network response that enhances breast tumour formation and growth.
    DOI:  https://doi.org/10.1038/s41556-022-00856-5
  38. Cureus. 2022 Feb;14(2): e21985
    Hunter Syndrome: The Phenotype of a Rare Storage Disease.
    Rute Sousa Martins, Sara Rocha, Arlindo Guimas, Rosa Ribeiro.
      Hunter syndrome is a rare lysosomal storage disorder with systemic involvement that occurs over time. Affected patients have coarse facial features, growth retardation with short stature, and skeletal deformities called dysostosis multiplex; joint stiffness, progressive mental retardation, and organomegaly are some of the clinical signs. It ranges from mild to severe manifestations and the distinction between them is related to neurological involvement. Cardiac and respiratory failure is commonly the cause of early death (before adulthood) for severe forms, but those with attenuated forms who have normal cognitive development can survive until late adulthood. Treatment with enzyme replacement therapy is available and can improve the prognosis of this disease. The authors present a case of a 36-year-old male with Hunter syndrome to show not only the clinical features typical of this multisystemic disease that should alert to a prompt investigation but also to remind that treatment must start as early as possible to reach the best outcome. Management of this disease is typically challenging and requires a multidisciplinary approach.
    Keywords:  dysostosis multiplex; hunter syndrome; inborn errors of metabolism; mucopolysaccharidosis; rare diseases
    DOI:  https://doi.org/10.7759/cureus.21985
  39. Trends Biochem Sci. 2022 Mar 12. pii: S0968-0004(22)00065-2. [Epub ahead of print]
    TCA cycle off, ATF4 on for metabolic homeostasis.
    Durga Mahor, Rishikesh Pandey, Vinay Bulusu.
      Tricarboxylic acid (TCA) cycle is a major hub for catabolic and anabolic reactions, yet cellular metabolic adaptations following its inhibition are largely unknown. Using multi-tiered omics approaches, Ryan et al. have shown convergent activation of the integrated stress response (ISR) through ATF4-mediated rewiring of cellular amino acid and redox metabolic pathways.
    Keywords:  ATF4; TCA cycle; fumarate hydratase; glutathione synthesis; integrated stress response; succinate dehydrogenase
    DOI:  https://doi.org/10.1016/j.tibs.2022.03.006
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