bims-tubesc 2022-02-06 papers

bims-tubesc

Biomed News

on Molecular mechanisms in tuberous sclerosis

Issue of 2022–02–06
twelve papers selected by

Neural Progenitors Promote Malformations in Tuberous Sclerosis Complex.
Beyond Protein Synthesis; The Multifaceted Roles of Tuberin in Cell Cycle Regulation.
Association of Early MRI Characteristics With Subsequent Epilepsy and Neurodevelopmental Outcomes in Children With Tuberous Sclerosis Complex.
A farnesyltransferase inhibitor restores cognitive deficits in Tsc2+/- mice through inhibition of Rheb1.
Population Pharmacokinetic Analysis and Dosing Optimization of Sirolimus in Children with Tuberous Sclerosis Complex.
New and emerging pharmacologic treatments for developmental and epileptic encephalopathies.
Low-grade oncocytic tumor of kidney harboring TSC/MTOR mutation: clinicopathologic, immunohistochemical and molecular characteristics support a distinct entity.
Loss of TSC1/TSC2 sensitizes immune checkpoint blockade in non-small cell lung cancer.
Defects in the autophagy lysosomal pathway in a cell model of disease-associated tau.
A Mixed Blood-Lymphatic Endothelial Cell Phenotype in LAM and IPF but not in Kaposi's Sarcoma or TSC.
E3 ligase RNF167 and deubiquitinase STAMBPL1 modulate mTOR and cancer progression.
LAMTOR1 inhibition of TRPML1-dependent lysosomal calcium release regulates dendritic lysosome trafficking and hippocampal neuronal function.

Cancer Discov. 2022 Feb 04.

Neural Progenitors Promote Malformations in Tuberous Sclerosis Complex.

Excessive neural progenitor proliferation generates lesions in tuberous sclerosis complex (TSC).

DOI: https://doi.org/10.1158/2159-8290.CD-RW2022-022
Front Cell Dev Biol. 2021 ;9 806521

Beyond Protein Synthesis; The Multifaceted Roles of Tuberin in Cell Cycle Regulation.

E Fidalgo da Silva, J Fong, A Roye-Azar, A Nadi, C Drouillard, A Pillon, L A Porter.

  The ability of cells to sense diverse environmental signals, including nutrient availability and conditions of stress, is critical for both prokaryotes and eukaryotes to mount an appropriate physiological response. While there is a great deal known about the different biochemical pathways that can detect and relay information from the environment, how these signals are integrated to control progression through the cell cycle is still an expanding area of research. Over the past three decades the proteins Tuberin, Hamartin and TBC1D7 have emerged as a large protein complex called the Tuberous Sclerosis Complex. This complex can integrate a wide variety of environmental signals to control a host of cell biology events including protein synthesis, cell cycle, protein transport, cell adhesion, autophagy, and cell growth. Worldwide efforts have revealed many molecular pathways which alter Tuberin post-translationally to convey messages to these important pathways, with most of the focus being on the regulation over protein synthesis. Herein we review the literature supporting that the Tuberous Sclerosis Complex plays a critical role in integrating environmental signals with the core cell cycle machinery.

Keywords:  TSC; cell cycle; cell growth; mTOR; tuberin; tuberous sclerosis complex

DOI:  https://doi.org/10.3389/fcell.2021.806521
Neurology. 2022 Jan 31. pii: 10.1212/WNL.0000000000200027. [Epub ahead of print]

Association of Early MRI Characteristics With Subsequent Epilepsy and Neurodevelopmental Outcomes in Children With Tuberous Sclerosis Complex.

EPISTOP consortium

BACKGROUND AND OBJECTIVE: Multiple factors have been found to contribute to the high risk of epilepsy in infants with Tuberous Sclerosis Complex (TSC), including evolution of EEG abnormalities, TSC gene mutation and MRI characteristics. The aim of the present prospective multi-center study was to: 1) identify early MRI biomarkers of epilepsy in infants with TSC aged < 6 months and before seizure onset, and 2) associate these MRI biomarkers with neurodevelopmental outcomes at 2 years of age. The study was part of the EPISTOP project.
METHODS: We evaluated brain MRIs performed in infants with TSC younger than 6 months of age. We used harmonized MRI-protocols across centers and children were monitored closely with neuropsychological evaluation, and serial video EEG. MRI characteristics defined as tubers, radial migration lines, white matter abnormalities, cysts, calcifications, subependymal nodules (SEN) and subependymal giant cell astrocytoma (SEGA) were visually evaluated and lesions were detected semi-automatically. Lesion to brain volume ratios were calculated and associated with epilepsy and neurodevelopmental outcomes at two years.
RESULTS: Lesions were assessed on MRIs from 77 TSC infants, 62 MRIs were sufficient for volume analysis. The presence of tubers and higher tuber-brain ratios were associated with the development of clinical seizures, independently of TSC gene mutation and preventive treatment. Furthermore, higher tuber-brain ratios were associated with lower cognitive and motor development quotients at two years, independently of TSC gene mutation and presence of epilepsy.
DISCUSSION: In infants with TSC, there is a significant association between characteristic TSC lesions detected on early brain MRI and development of clinical seizures, as well as neurodevelopmental outcomes in the first two years of life. According to our results, early brain MRI findings may guide clinical care for young children with TSC.
CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that in infants with TSC, there is a significant association between characteristic TSC lesions on early brain MRI and the development of clinical seizures and neurodevelopmental outcomes in the first two years of life.

DOI: https://doi.org/10.1212/WNL.0000000000200027
J Neurosci. 2022 Feb 04. pii: JN-RM-0449-21. [Epub ahead of print]

A farnesyltransferase inhibitor restores cognitive deficits in Tsc2+/- mice through inhibition of Rheb1.

Hiroko Sugiura, Tadayuki Shimada, Keiko Moriya-Ito, Jun-Ichi Goto, Hiroki Fujiwara, Rie Ishii, Hiroshi Shitara, Choji Taya, Satoshi Fujii, Toshiyuki Kobayashi, Okio Hino, Paul F Worley, Kanato Yamagata.

Tuberous sclerosis complex (TSC) is caused by mutations in Tsc1 or Tsc2, whose gene products inhibit the small G-protein Rheb1. Rheb1 activates mTORC1, which may cause refractory epilepsy, intellectual disability and autism. The mTORC1 inhibitors have been used for TSC patients with intractable epilepsy. However, its effectiveness for cognitive symptoms remains unclear. We found a new signaling pathway for synapse formation through Rheb1 activation, but not mTORC1. Here, we show that treatment with the farnesyltransferase inhibitor lonafarnib increased unfarnesylated (inactive) Rheb1 levels and restored synaptic abnormalities in cultured Tsc2+/- neurons, whereas rapamycin did not enhance spine synapse formation. Lonafarnib treatment also restored the plasticity-related Arc expression in cultured Tsc2+/- neurons. Lonafarnib action was partly dependent on the Rheb1 reduction with syntenin. Oral administration of lonafarnib increased unfarnesylated protein levels without affecting mTORC1and MAP kinase signalings, and restored dendritic spine morphology in the hippocampi of male Tsc2+/- mice. In addition, lonafarnib treatment ameliorated contextual memory impairments and restored memory-related Arc expression in male Tsc2+/- mice in vivo Heterozygous Rheb1 knockout in male Tsc2+/- mice reproduced the results observed with pharmacological treatment. These results suggest that the Rheb1 activation may be responsible for synaptic abnormalities and memory impairments in Tsc2+/- mice, and its inhibition by lonafarnib could provide insight into potential treatment options for TSC-associated neuropsychiatric disorders (TANDs).SIGNIFICANCE STATEMENTTuberous sclerosis complex (TSC) is an autosomal dominant disease that causes neuropsychiatric symptoms, including intractable epilepsy, intellectual disability (ID) and autism. No pharmacological treatment for ID is reported so far. To develop a pharmacological treatment for ID, we investigated the mechanism of TSC and found Rheb1 activation is responsible for synaptic abnormalities in TSC neurons. To inhibit Rheb1 function, we used farnesyltransferase inhibitor lonafarnib, because farnesylation of Rheb1 is required for its activation. Lonafarnib treatment increased inactive Rheb1, and recovered proper synapse formation and plasticity-related Arc expression in TSC neurons. Furthermore, in vivo lonafarnib treatment restored contextual memory and Arc induction in TSC mice. Taken together, Rheb1 inhibition by lonafarnib could provide insight into potential treatments for TSC-associated ID.

DOI: https://doi.org/10.1523/JNEUROSCI.0449-21.2022
J Clin Pharmacol. 2022 Jan 30.

Population Pharmacokinetic Analysis and Dosing Optimization of Sirolimus in Children with Tuberous Sclerosis Complex.

SiChan Li, Min Zhan, SanLan Wu, JianXiang Liao, Hua Xu, Dan Sun, Xia Zhao, Yang Wang.

  Sirolimus is confirmed to be effective in the treatment of tuberous sclerosis complex (TSC) and related disorders. The study aims to establish a population pharmacokinetic (PopPK) model of oral sirolimus for children with TSC and provide an evidence-based approach for individualization of sirolimus dosing in the pediatric population. A total of 64 children were recruited in this multicenter, retrospective pharmacokinetic study. Whole blood concentrations of sirolimus, demographic and clinical information were collected and analyzed using a nonlinear mixed-effects population modeling method. The final model was internally and externally validated. Then Monte Carlo simulations were performed to evaluate and optimize the dosing regimens. In addition, the efficacy and safety of sirolimus therapy was assessed retrospectively in patients with epilepsy or cardiac rhabdomyomas associated with TSC. Finally, the sirolimus pharmacokinetics profile was described by a one-compartment model with first-order absorption and elimination along with body weight and total daily dose as significant covariates. The typical population parameter estimates of apparent volume of distribution and apparent clearance were 69.48 L and 2.79 L/h, respectively. Simulations demonstrated that dosage regimens stratified by body surface area may be more appropriate for children with TSC. These findings could be used to inform individualized dosing strategies of sirolimus for pediatric patients with TSC. This article is protected by copyright. All rights reserved.

Keywords:  children; dosing; population pharmacokinetics; sirolimus; tuberous sclerosis

DOI:  https://doi.org/10.1002/jcph.2033
Curr Opin Neurol. 2022 Jan 31.

New and emerging pharmacologic treatments for developmental and epileptic encephalopathies.

Alejandra Vasquez, Ersida Buraniqi, Elaine C Wirrell.

PURPOSE OF REVIEW: Summarize evidence on Developmental and Epileptic Encephalopathies (DEEs) treatments focusing on new and emerging pharmacologic therapies (see Video, http://links.lww.com/CONR/A61, Supplementary Digital Content 1, which provides an overview of the review).
RECENT FINDINGS: Advances in the fields of molecular genetics and neurobiology have led to the recognition of underlying pathophysiologic mechanisms involved in an increasing number of DEEs that could be targeted with precision therapies or repurposed drugs, some of which are currently being evaluated in clinical trials. Prompt, optimal therapy is critical, and promising therapies approved or in clinical trials for tuberous sclerosis complex, Dravet and Lennox-Gastaut Syndromes including mammalian target of rapamycin inhibitors, selective membrane channel and antisense oligonucleotide modulation, and repurposed drugs such as fenfluramine, stiripentol and cannabidiol, among others, may improve seizure burden and neurological outcomes. There is an urgent need for collaborative efforts to evaluate the efficacy and safety of emerging DEEs therapies.
SUMMARY: Development of new therapies promise to address unmet needs for patients with DEEs, including improvement of neurocognitive function and quality of life.

DOI: https://doi.org/10.1097/WCO.0000000000001029
Virchows Arch. 2022 Jan 31.

Low-grade oncocytic tumor of kidney harboring TSC/MTOR mutation: clinicopathologic, immunohistochemical and molecular characteristics support a distinct entity.

Hui-Zhi Zhang, Qiu-Yuan Xia, Shu-Yan Wang, Meng-Jie Shi, Su-Ying Wang.

  Low-grade oncocytic tumor (LOT) has recently been described as a distinct renal tumor. LOT shows consistent morphologic features and a CK7-positive/CD117-negative immunophenotype. To examine the clinicopathological, immunohistochemical, and molecular features of LOT, we searched our institutional archives and identified seven cases of LOT. All patients were female, with a mean age of 66 years (range 44-79 years). The average tumor size was 3.2 cm (range 1.6-5.5 cm). Macroscopically, the tumors showed tan-brown and solid cut surfaces. Microscopically, the tumors showed compact nested to solid growth pattern, three cases with areas of edematous stroma containing loosely connected small clusters, cords or dispersed single tumor cells. The tumor cells had uniformly round to oval nuclei with eosinophilic cytoplasm, and showed perinuclear halos. Two cases focally had nuclear irregularities and binucleated cells were occasionally seen in three cases. Immunohistochemically, diffuse positivity for CK7 and lack of CD117 expression were present in all cases. All of the tumors were negative for CD10, CK20, vimentin, CA9, TFE3, TFEB, HMB45, and Melan-A. All tumors were positive for MTOR and negative for Cathepsin-K. FH and SDHB were retained. Next generation sequencing identified genetic variations in the MTOR pathway related genes: TSC1 (4/7), TSC2 (5/7), and MTOR (1/7). All patients were alive and without disease progression, after a mean follow-up of 43 months (range 6-89 months). LOT is an uncommon eosinophilic renal neoplasm with unique morphological and characteristic immunophenotypic features, and may represent an emerging separate renal entity characterized by mutations in the TSC/MTOR pathway.

Keywords:  Chromophobe renal cell carcinoma; Low-grade oncocytic tumor; MTOR; Mutation; Oncocytic renal tumor; TSC

DOI:  https://doi.org/10.1007/s00428-022-03283-x
Sci Adv. 2022 Feb 04. 8(5): eabi9533

Loss of TSC1/TSC2 sensitizes immune checkpoint blockade in non-small cell lung cancer.

Qingyuan Huang, Fei Li, Hai Hu, Zhaoyuan Fang, Zhendong Gao, Guozhan Xia, Wai-Lung Ng, Alireza Khodadadi-Jamayran, Ting Chen, Jiehui Deng, Hua Zhang, Christina Almonte, Kristen Labbe, Han Han, Ke Geng, Sittinon Tang, Gordon J Freeman, Yuan Li, Haiquan Chen, Kwok-Kin Wong.

Tuberous sclerosis complex subunit 1 (TSC1) and 2 (TSC2) are frequently mutated in non-small cell lung cancer (NSCLC), however, their effects on antitumor immunity remained unexplored. A CRISPR screening in murine KrasG12D/Trp53-/- (KP) model identified Tsc1 and Tsc2 as potent regulators of programmed cell death ligand 1 (Pd-l1) expression in vitro and sensitivity to anti-programmed cell death receptor 1 (PD-1) treatment in vivo. TSC1 or TSC2 knockout (KO) promoted the transcriptional and membrane expression of PD-L1 in cell lines. TSC2-deficient tumors manifested an inflamed microenvironment in patient samples and The Cancer Genome Atlas dataset. In syngeneic murine models, KP-Tsc2-KO tumors showed notable response to anti-PD-1 antibody treatment, but Tsc2-wild-type tumors did not. Patients with TSC1/TSC2-mutant NSCLC receiving immune checkpoint blockade (ICB) had increased durable clinical benefit and survival. Collectively, TSC1/TSC2 loss defines a distinct subtype of NSCLC characterized as inflamed tumor microenvironment and superior sensitivity to ICB.

DOI: https://doi.org/10.1126/sciadv.abi9533
Alzheimers Dement. 2021 Dec;17 Suppl 3 e051303

Defects in the autophagy lysosomal pathway in a cell model of disease-associated tau.

Saskia J Pollack, Dina Dakkak, Tong Guo, Patricia Gómez-Suaga, Wendy Noble, Diane P Hanger.

BACKGROUND: Intracellular accumulation of insoluble tau is an important hallmark of Alzheimer's disease (AD) and related tauopathies. We have previously identified in human tauopathy brain a truncated tau species (Tau35), comprising the C-terminal half with four microtubule-binding repeats. Minimal Tau35 expression in transgenic mice results in a progressive tauopathy phenotype including tau phosphorylation and aggregation, cognitive and behavioural abnormalities and impaired protein clearance. The autophagy-lysosomal pathway (ALP) plays a crucial role in the clearance of protein aggregates and defects in ALP are associated with the pathogenesis of AD. We sought to explore the effect of Tau35 expression on the ALP and whether autophagy is disrupted due to lysosomal dysfunction.
METHODS: Chinese hamster ovary (CHO) cells stably expressing Tau35 (CHO-Tau35) or full-length human 2N4R tau (CHO-FL) were generated. Primary cortical neurons from Tau35 transgenic and wild-type mice were cultured for 14 days in vitro(DIV) and brain homogenates were prepared from mice aged 4 and 12 months. The effect of Tau35 on the ALP was examined using immunofluorescence and western blots.
RESULT: Nuclear translocation of transcription factor EB (TFEB), a key mediator of lysosomal biogenesis, was significantly reduced in both CHO-FL and CHO-Tau35 cells. However, only CHO-Tau35 cells exhibited disrupted mammalian target of rapamycin complex 1 (mTORC1) activity and autophagic flux. Expression of ALP markers, including LC3-I/II, LAMP1, LAMP2 and cathepsin D, were also reduced in CHO-Tau35 cells and in post-symptomatic Tau35 transgenic mice.
CONCLUSIONS: Our findings suggest that N-terminally cleaved tau damages both lysosomal clearance of cellular proteins and lysosomal biogenesis. The Tau35-expressing cultured neurons will provide a useful tool to explore molecular mechanisms underlying tau-induced lysosomal dysfunction, which may lead to the identification of novel therapeutic targets for dementia.

DOI: https://doi.org/10.1002/alz.051303
Am J Respir Cell Mol Biol. 2022 Feb 01.

A Mixed Blood-Lymphatic Endothelial Cell Phenotype in LAM and IPF but not in Kaposi's Sarcoma or TSC.

Gustavo Pacheco-Rodriguez, Connie G Glasgow, Yoshihiko Ikeda, Wendy K Steagall, Zu-Xi Yu, Katsuya Tsukada, Brent W Beasley, Bernadette R Gochuico, Gulsun Erdag, Kathryn Lurain, Michelly Sampaio De Melo, Ramya Ramaswami, Thomas N Darling, Armando Filie, Joel Moss.



Keywords:  Tuberous Sclerosis Complex; lymphangiogenesis; metastasis

DOI:  https://doi.org/10.1165/rcmb.2021-0293LE
Mol Cell. 2022 Jan 25. pii: S1097-2765(22)00002-8. [Epub ahead of print]

E3 ligase RNF167 and deubiquitinase STAMBPL1 modulate mTOR and cancer progression.

Dong Wang, Chenchen Xu, Wenyu Yang, Jie Chen, Yuhui Ou, Yuanyuan Guan, Jialiang Guan, Ying Liu.

  The mTOR complex 1 (mTORC1) is an essential metabolic hub that coordinates cellular metabolism with the availability of nutrients, including amino acids. Sestrin2 has been identified as a cytosolic leucine sensor that transmits leucine status signals to mTORC1. In this study, we identify an E3 ubiquitin ligase RING finger protein 167 (RNF167) and a deubiquitinase STAMBPL1 that function in concert to control the polyubiquitination level of Sestrin2 in response to leucine availability. Ubiquitination of Sestrin2 promotes its interaction with GATOR2 and inhibits mTORC1 signaling. Bioinformatic analysis reveals decreased RNF167 expression and increased STAMBPL1 expression in gastric and colorectal tumors. Knockout of STAMBPL1 or correction of the heterozygous STAMBPL1 mutation in a human colon cancer cell line suppresses xenograft tumor growth. Lastly, a cell-permeable peptide that blocks the STAMBPL1-Sestrin2 interaction inhibits mTORC1 and provides a potential option for cancer therapy.

Keywords:  Sestrin2; amino acid sensing; colorectal cancer; mTOR; tumorigenesis; ubiquitination

DOI:  https://doi.org/10.1016/j.molcel.2022.01.002
EMBO J. 2022 Jan 31. e108119

LAMTOR1 inhibition of TRPML1-dependent lysosomal calcium release regulates dendritic lysosome trafficking and hippocampal neuronal function.

Jiandong Sun, Yan Liu, Xiaoning Hao, Weiju Lin, Wenyue Su, Emerald Chiang, Michel Baudry, Xiaoning Bi.

  Lysosomes function not only as degradatory compartments but also as dynamic intracellular calcium ion stores. The transient receptor potential mucolipin 1 (TRPML1) channel mediates lysosomal Ca2+ release, thereby participating in multiple cellular functions. The pentameric Ragulator complex, which plays a critical role in the activation of mTORC1, is also involved in lysosomal trafficking and is anchored to lysosomes through its LAMTOR1 subunit. Here, we report that the Ragulator restricts lysosomal trafficking in dendrites of hippocampal neurons via LAMTOR1-mediated tonic inhibition of TRPML1 activity, independently of mTORC1. LAMTOR1 directly interacts with TRPML1 through its N-terminal domain. Eliminating this inhibition in hippocampal neurons by LAMTOR1 deletion or by disrupting LAMTOR1-TRPML1 binding increases TRPML1-mediated Ca2+ release and facilitates dendritic lysosomal trafficking powered by dynein. LAMTOR1 deletion in the hippocampal CA1 region of adult mice results in alterations in synaptic plasticity, and in impaired object-recognition memory and contextual fear conditioning, due to TRPML1 activation. Mechanistically, changes in synaptic plasticity are associated with increased GluA1 dephosphorylation by calcineurin and lysosomal degradation. Thus, LAMTOR1-mediated inhibition of TRPML1 is critical for regulating dendritic lysosomal motility, synaptic plasticity, and learning.

Keywords:  LTD; LTP; calcineurin; calcium; dynein

DOI:  https://doi.org/10.15252/embj.2021108119