bims-musmir 2024-09-15 papers

bims-musmir

Biomed News

on microRNAs in muscle

Issue of 2024–09–15
fiveteen papers selected by
Katarzyna Agnieszka Goljanek-Whysall, University of Galway

Akt1 deficiency does not affect fiber type composition or mitochondrial protein expression in skeletal muscle of male mice.
Hyperphosphatemia Contributes to Skeletal Muscle Atrophy in Mice.
CHCHD10P80L knock-in zebrafish display a mild ALS-like phenotype.
Long-term effects of the chronic administration of doxorubicin on aged skeletal muscle: An exploratory study in mice.
Contractile regulation of the glucocorticoid-sensitive transcriptome in young and aged skeletal muscle.
Aging-Related Metabolome Analysis of the Masseter Muscle in Senescence-Accelerated Mouse-Prone 8.
Characterization of SMA Type II Skeletal Muscle from Treated Patients shows Mitochondrial Deficiency and Denervation.
Activation of the muscle-to-brain axis ameliorates neurocognitive deficits in an Alzheimer's disease mouse model via enhancing neurotrophic and synaptic signaling.
Lifelong dietary protein restriction induces denervation and skeletal muscle atrophy in mice.
miR-3529-3p/ABCA1 axis regulates smooth muscle cell homeostasis by enhancing inflammation via JAK2/STAT3 pathway.
MBNL splicing factors regulate the microtranscriptome of skeletal muscles.
A robust evaluation of TDP-43, poly GP, cellular pathology and behavior in a AAV-C9ORF72 (G4C2)66 mouse model.
Loss-of-function variants in RNA binding motif protein X-linked induce neuronal defects contributing to amyotrophic lateral sclerosis pathogenesis.
Prolonged loss of intercostal muscle mass and its predictors in COVID-19 patients: A retrospective study from tertiary hospital.
CCDC78: Unveiling the Function of a Novel Gene Associated with Hereditary Myopathy.

Physiol Rep. 2024 Sep;12(17): e70048

Akt1 deficiency does not affect fiber type composition or mitochondrial protein expression in skeletal muscle of male mice.

Tatsuya Miyaji, Ryuichi Kasuya, Atsushi Sawada, Daisuke Sawamura, Yu Kitaoka, Mitsunori Miyazaki.

  Insulin-like growth factor-1-induced activation of ATP citrate lyase (ACLY) improves muscle mitochondrial function through an Akt-dependent mechanism. In this study, we examined whether Akt1 deficiency alters skeletal muscle fiber type and mitochondrial function by regulating ACLY-dependent signaling in male Akt1 knockout (KO) mice (12-16 weeks old). Akt1 KO mice exhibited decreased body weight and muscle wet weight, with reduced cross-sectional areas of slow- and fast-type muscle fibers. Loss of Akt1 did not affect the phosphorylation status of ACLY in skeletal muscle. The skeletal muscle fiber type and expression of mitochondrial oxidative phosphorylation complex proteins were unchanged in Akt1 KO mice compared with the wild-type control. These observations indicate that Akt1 is important for the regulation of skeletal muscle fiber size, whereas the regulation of muscle fiber type and muscle mitochondrial content occurs independently of Akt1 activity.

Keywords:  Akt1; glycolysis; mitochondria; skeletal muscle

DOI:  https://doi.org/10.14814/phy2.70048
Int J Mol Sci. 2024 Aug 28. pii: 9308. [Epub ahead of print]25(17):

Hyperphosphatemia Contributes to Skeletal Muscle Atrophy in Mice.

Kylie Heitman, Seth Bollenbecker, Jordan Bradley, Brian Czaya, Abul Fajol, Sarah Madison Thomas, Qing Li, Svetlana Komarova, Stefanie Krick, Glenn C Rowe, Matthew S Alexander, Christian Faul.

  Chronic kidney disease (CKD) is associated with various pathologic changes, including elevations in serum phosphate levels (hyperphosphatemia), vascular calcification, and skeletal muscle atrophy. Elevated phosphate can damage vascular smooth muscle cells and cause vascular calcification. Here, we determined whether high phosphate can also affect skeletal muscle cells and whether hyperphosphatemia, in the context of CKD or by itself, is associated with skeletal muscle atrophy. As models of hyperphosphatemia with CKD, we studied mice receiving an adenine-rich diet for 14 weeks and mice with deletion of Collagen 4a3 (Col4a3-/-). As models of hyperphosphatemia without CKD, we analyzed mice receiving a high-phosphate diet for three and six months as well as a genetic model for klotho deficiency (kl/kl). We found that adenine, Col4a3-/-, and kl/kl mice have reduced skeletal muscle mass and function and develop atrophy. Mice on a high-phosphate diet for six months also had lower skeletal muscle mass and function but no significant signs of atrophy, indicating less severe damage compared with the other three models. To determine the potential direct actions of phosphate on skeletal muscle, we cultured primary mouse myotubes in high phosphate concentrations, and we detected the induction of atrophy. We conclude that in experimental mouse models, hyperphosphatemia is sufficient to induce skeletal muscle atrophy and that, among various other factors, elevated phosphate levels might contribute to skeletal muscle injury in CKD.

Keywords:  chronic kidney disease; hyperphosphatemia; phosphate; sarcopenia; skeletal muscle atrophy

DOI:  https://doi.org/10.3390/ijms25179308
Exp Neurol. 2024 Sep 09. pii: S0014-4886(24)00271-1. [Epub ahead of print] 114945

CHCHD10P80L knock-in zebrafish display a mild ALS-like phenotype.

Virginie Petel Légaré, Ziyaan A Harji, Christian J Rampal, Hana Antonicka, Tyler J N Gurberg, Olivia Persia, Esteban C Rodríguez, E A Shoubridge, Gary A B Armstrong.

  Mutations in the nuclear-encoded mitochondrial gene CHCHD10 have been observed in patients with a spectrum of diseases that include amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). To investigate the pathogenic nature of disease-associated variants of CHCHD10 we generated a zebrafish knock-in (KI) model expressing the orthologous ALS-associated CHCHD10P80L variant (zebrafish: Chchd10P83L). Larval chchd10P83L/P83L fish displayed reduced Chchd10 protein expression levels, motor impairment, reduced survival and abnormal neuromuscular junctions (NMJ). These deficits were not accompanied by changes in transcripts involved in the integrated stress response (ISR), phenocopying previous findings in our knockout (chchd10-/-). Adult, 11-month old chchd10P83L/P83L zebrafish, displayed smaller slow- and fast-twitch muscle cell cross-sectional areas compared to wild type zebrafish muscle cells. Motoneurons in the spinal cord of chchd10P83L/P83L zebrafish displayed similar cross-sectional areas to that of wild type motor neurons and significantly fewer motor neurons were observed when compared to chchd2-/- adult spinal cords. Bulk RNA sequencing using whole spinal cords of 7-month old fish revealed transcriptional changes associated with neuroinflammation, apoptosis, amino acid metabolism and mt-DNA inflammatory response in our chchd10P83L/P83L model. The findings presented here, suggest that the CHCHD10P80L variant confers an ALS-like phenotype when expressed in zebrafish.

Keywords:  Als; CHCHD10; Knock-in mutation; Mitochondria; Motor neuron; Neurodegeneration; Zebrafish

DOI:  https://doi.org/10.1016/j.expneurol.2024.114945
Biochem Biophys Res Commun. 2024 Sep 03. pii: S0006-291X(24)01186-0. [Epub ahead of print]733 150650

Long-term effects of the chronic administration of doxorubicin on aged skeletal muscle: An exploratory study in mice.

Alexandra Moreira-Pais, Rita Ferreira, Telmo Baltazar, Maria João Neuparth, Rui Vitorino, Ana Reis-Mendes, Vera Marisa Costa, Paula A Oliveira, José A Duarte.

  The widely used chemotherapeutic drug doxorubicin (DOX) has been associated with adverse effects on the skeletal muscle, which can persist for years after the end of the treatment. These adverse effects may be exacerbated in older patients, whose skeletal muscle might already be impaired by aging. Nonetheless, the mediators responsible for DOX-induced myotoxicity are still largely unidentified, particularly the ones involved in the long-term effects that negatively affect the quality of life of the patients. Therefore, this study aimed to investigate the long-term effects of the chronic administration of DOX on the soleus muscle of aged mice. For that and to mimic the clinical regimen, a dose of 1.5 mg kg-1 of DOX was administered two times per week for three consecutive weeks in a cumulative dose of 9 mg kg-1 to 19-month-old male mice, which were sacrificed two months after the last administration. Body wasting and the atrophy of the soleus muscle, as measured by a decrease in the cross-sectional area of the soleus muscle fibers, were identified as long-term effects of DOX administration. The atrophy observed was correlated with increased reactive oxygen species production and caspase-3 activity. An impaired skeletal muscle regeneration was also suggested due to the correlation between satellite cells activation and the soleus muscle fibers atrophy. Systemic inflammation, skeletal muscle energy metabolism and neuromuscular junction-related markers do not appear to be involved in the long-term DOX-induced skeletal muscle atrophy. The data provided by this study shed light on the mediators involved in the overlooked long-term DOX-induced myotoxicity, paving the way to the improvement of the quality of life and survival rates of older cancer patients.

Keywords:  Aging; Chemotherapy; Muscle wasting; Oxidative stress; Sarcopenia

DOI:  https://doi.org/10.1016/j.bbrc.2024.150650
Am J Physiol Endocrinol Metab. 2024 Sep 11.

Contractile regulation of the glucocorticoid-sensitive transcriptome in young and aged skeletal muscle.

Grant R Laskin, David S Waddell, Cynthia Vied, Bradley S Gordon.

  Elevated glucocorticoids alter the skeletal muscle transcriptome to induce a myopathy characterized by muscle atrophy, muscle weakness, and decreased metabolic function. These effects are more likely to occur and be more severe in aged muscle. Resistance exercise can blunt development of glucocorticoid myopathy in young muscle, but the potential to oppose the signals initiating myopathy in aged muscle is unknown. To answer this, young (4-month-old) and aged (24-25-month-old) male C57BL/6 mice were randomized to receive either an intraperitoneal (IP) injection of dexamethasone (DEX; 2 mg/kg) or saline as a control. Two hours post-injections, tibialis anterior (TA) muscles of mice were subjected to unilateral high force contractions. Muscles were harvested four hours later. The glucocorticoid- and contraction-sensitive genes were determined by RNA sequencing. The number of glucocorticoid-sensitive genes was similar between young and aged muscle. Contractions opposed changes to more glucocorticoid-sensitive genes in aged muscle, with this outcome primarily occurring when hormone levels were elevated. Glucocorticoid-sensitive gene programs opposed by contractions were primarily related to metabolism in young mice and muscle size regulation and inflammation in aged mice. In silico analysis implied Peroxisome proliferator-activated receptor gamma-1 (PPARG) contributed to the contraction-induced opposition of glucocorticoid-sensitive genes in aged muscle. Increasing PPARG expression in the TA of aged mice using Adeno-associated virus serotype 9 partially counteracted the glucocorticoid-induced reduction in Runt-related transcription factor 1 (Runx1) mRNA content, recapitulating the effects observed by contractions. Overall, these data contribute to our understanding of the contractile regulation of the glucocorticoid transcriptome in aged skeletal muscle.

Keywords:  aging; glucocorticoid myopathy; pparg; resistance exercise

DOI:  https://doi.org/10.1152/ajpendo.00223.2024
Int J Mol Sci. 2024 Sep 07. pii: 9684. [Epub ahead of print]25(17):

Aging-Related Metabolome Analysis of the Masseter Muscle in Senescence-Accelerated Mouse-Prone 8.

Yoshiaki Kato, Teruhide Hoshino, Yudai Ogawa, Keisuke Sugahara, Akira Katakura.

  Frailty is a vulnerable state that marks the transition to long-term care for older people. Early detection and prevention of sarcopenia, the main symptom of frailty, are important to ensure an excellent quality of life for older people. Recently, the relationship between frailty, sarcopenia, and oral function has been attracting attention. This study aimed to clarify the changes in metabolites and metabolic pathways due to aging in the masseter muscle of senescence-accelerated mouse-prone 8 (SAMP8) mice. A capillary electrophoresis-mass spectrometry metabolome analysis was performed on the masseter muscle of 12-week-old, 40-week-old, and 55-week-old mice. The expression of enzymes involved in metabolome pathways considered to be related to aging was confirmed using reverse transcription polymerase chain reaction. Clear metabolic fluctuations were observed between 12, 40-week-old, and 55-week-old SAMP8 mice. The extracted metabolic pathways were the glycolysis, polyamine metabolome, and purine metabolome pathways. Nine fluctuated metabolites were common among the groups. Spermidine and Val were increased, which was regarded as a characteristic change in the masseter muscle due to aging. In conclusion, the age-related metabolic pathways in SAMP8 mice were the glycolysis, polyamine metabolome, and purine metabolome pathways. The increased spermidine and Val levels in the masseter muscle compared with the lower limbs are characteristic changes.

Keywords:  aging; masseter muscle; metabolites; metabolome analysis; senescence-accelerated mouse

DOI:  https://doi.org/10.3390/ijms25179684
JCI Insight. 2024 Sep 12. pii: e180992. [Epub ahead of print]

Characterization of SMA Type II Skeletal Muscle from Treated Patients shows Mitochondrial Deficiency and Denervation.

Fiorella Grandi, Stéphanie Astord, Sonia Pezet, Elèna Gidaja, Sabrina Mazzucchi, Maud Chapart, Stéphane Vasseur, Kamel Mamchaoui, Piera Smeriglio.

  Spinal muscular atrophy (SMA) is a recessive, developmental disorder caused by the genetic loss or mutation of the gene SMN1 (Survival of Motor Neuron 1). SMA is characterized by neuromuscular symptoms and muscle weakness. Several years ago, SMA treatment underwent a radical transformation, with the approval of three different SMN-dependent disease modifying therapies. This includes two SMN2 splicing therapies - Risdiplam and Nusinersen. One main challenge for Type II SMA patients treated with these drugs is ongoing muscle fatigue, limited mobility, and other skeletal problems. To date, few molecular studies have been conducted on SMA-patient derived tissues after treatment, limiting our understanding of what targets remain after the principal spinal cord targeted therapies are applied. Therefore, we collected paravertebral muscle from eight Type II patients undergoing spinal surgery for scoliosis and seven controls. We used RNA-sequencing to characterize their transcriptional profiles and correlate these with muscle histology. Despite the limited cohort size and heterogeneity, we observed a consistent loss of oxidative phosphorylation machinery of the mitochondria, a decrease in mitochondrial DNA copy number, and a correlation between signals of cellular stress, denervation and increased fibrosis. This work provides new putative targets for combination therapies for Type II SMA.

Keywords:  Bioinformatics; Genetics; Muscle biology; Neuromuscular disease; Skeletal muscle

DOI:  https://doi.org/10.1172/jci.insight.180992
Geroscience. 2024 Sep 13.

Activation of the muscle-to-brain axis ameliorates neurocognitive deficits in an Alzheimer's disease mouse model via enhancing neurotrophic and synaptic signaling.

Hash Brown Taha, Allison Birnbaum, Ian Matthews, Karel Aceituno, Jocelyne Leon, Max Thorwald, Jose Godoy-Lugo, Constanza J Cortes.

  Skeletal muscle regulates central nervous system (CNS) function and health, activating the muscle-to-brain axis through the secretion of skeletal muscle-originating factors ("myokines") with neuroprotective properties. However, the precise mechanisms underlying these benefits in the context of Alzheimer's disease (AD) remain poorly understood. To investigate muscle-to-brain axis signaling in response to amyloid β (Aβ)-induced toxicity, we generated 5xFAD transgenic female mice with enhanced skeletal muscle function (5xFAD;cTFEB;HSACre) at prodromal (4-months old) and late (8-months old) symptomatic stages. Skeletal muscle TFEB overexpression reduced Aβ plaque accumulation in the cortex and hippocampus at both ages and rescued behavioral neurocognitive deficits in 8-month-old 5xFAD mice. These changes were associated with transcriptional and protein remodeling of neurotrophic signaling and synaptic integrity, partially due to the CNS-targeting myokine prosaposin (PSAP). Our findings implicate the muscle-to-brain axis as a novel neuroprotective pathway against amyloid pathogenesis in AD.

Keywords:  Muscle; Muscle-to-brain axis; Myokines; Plaques; Synapse

DOI:  https://doi.org/10.1007/s11357-024-01345-3
Free Radic Biol Med. 2024 Sep 06. pii: S0891-5849(24)00648-8. [Epub ahead of print]

Lifelong dietary protein restriction induces denervation and skeletal muscle atrophy in mice.

Ufuk Ersoy, Atilla Emre Altinpinar, Ioannis Kanakis, Moussira Alameddine, Anna Gioran, Niki Chondrogianni, Susan E Ozanne, Mandy Jayne Peffers, Malcolm J Jackson, Katarzyna Goljanek-Whysall, Aphrodite Vasilaki.

  As a widespread global issue, protein deficiency hinders development and optimal growth in offspring. Maternal low-protein diet influences the development of age-related diseases, including sarcopenia, by altering the epigenome and organ structure through potential increase in oxidative stress. However, the long-term effects of lactational protein restriction or postnatal lifelong protein restriction on the neuromuscular system have yet to be elucidated. Our results demonstrated that feeding a normal protein diet after lactational protein restriction did not have significant impacts on the neuromuscular system in later life. In contrast, a lifelong low-protein diet induced a denervation phenotype and led to demyelination in the sciatic nerve, along with an increase in the number of centralised nuclei and in the gene expression of atrogenes at 18 months of age, indicating an induced skeletal muscle atrophy. These changes were accompanied by an increase in proteasome activity in skeletal muscle, with no significant alterations in oxidative stress or mitochondrial dynamics markers in skeletal muscle later in life. Thus, lifelong protein restriction may induce skeletal muscle atrophy through changes in peripheral nerves and neuromuscular junctions, potentially contributing to the early onset or exaggeration of sarcopenia.

Keywords:  Skeletal muscle; atrophy; denervation; oxidative stress; protein restriction; proteostasis

DOI:  https://doi.org/10.1016/j.freeradbiomed.2024.09.005
Front Cardiovasc Med. 2024 ;11 1441123

miR-3529-3p/ABCA1 axis regulates smooth muscle cell homeostasis by enhancing inflammation via JAK2/STAT3 pathway.

Tingyu Wang, You Yu, Yinglong Ding, Ziying Yang, Shumin Jiang, Faxiong Gao, Shan Liu, Lianbo Shao, Zhenya Shen.

   Background: Thoracic Aortic Dissection (TAD) is a life-threatening disease without effective drug treatments. The disruption of HASMCs homeostasis is one direct histopathologic alteration in TAD pathological process. Several miRNAs have been shown abnormally expressed in TAD and to regulate HASMCs homeostasis. The primary goal of this study is to identify the miRNAs and the specific mechanisms that lead to HASMCs homeostasis disruption.
Methods: Bulk miRNA sequencing was performed to explore the aberrantly expressed miRNA profile in TAD, and differentially expressed miRNAs were verified with qRT-PCR. To explore the role of the key miRNAs (miR-3529) in HASMCs homeostasis, we overexpressed this miRNA with lentivirus in HASMCs. Integrative transcriptomics and metabolomics analysis were used to uncover the functional roles of this miRNA in regulating HASMCs homeostasis. Further, the target gene of miR-3529 was predicted by bioinformatics and verified through a dual-luciferase reporter assay.
Results: Bulk miRNA sequencing showed miR-3529 was elevated in TAD tissues and confirmed by qRT-PCR. Further experimental assay revealed miR-3529 upregulation induced HASMCs homeostasis disruption, accompanied by reducing contractile markers and increasing pro-inflammatory cytokines. Integrative transcriptomics and metabolomics analysis showed that miR-3529 overexpression altered the metabolic profile of HASMC, particularly lipid metabolism. ABCA1 was found to be a direct target of miR-3529. Mechanistically, the miR-3529/ABCA1 axis disrupted HASMCs homeostasis through the JAK2/STAT3 signaling pathway.
Conclusions: miR-3529 is elevated in TAD patients and disrupts HASMCs homeostasis by reprogramming metabolism through the JAK2/STAT3 signaling pathway. These findings favor a role for miR-3529 as a novel target for TAD therapy.

Keywords:  ABCA1; homeostasis; miR-3529-3p; smooth muscle cell; thoracic aortic dissection

DOI:  https://doi.org/10.3389/fcvm.2024.1441123
Nucleic Acids Res. 2024 Sep 11. pii: gkae774. [Epub ahead of print]

MBNL splicing factors regulate the microtranscriptome of skeletal muscles.

Agnieszka Piasecka, Michał W Szcześniak, Michał Sekrecki, Arkadiusz Kajdasz, Łukasz J Sznajder, Anna Baud, Krzysztof Sobczak.

Muscleblind like splicing regulators (MBNLs) govern various RNA-processing steps, including alternative splicing, polyadenylation, RNA stability and mRNA intracellular localization. In myotonic dystrophy type 1 (DM1), the most common muscular dystrophy in adults, MBNLs are sequestered on toxic RNA containing expanded CUG repeats, which leads to disruption of MBNL-regulated processes and disease features of DM1. Herein, we show the significance of MBNLs in regulating microtranscriptome dynamics during the postnatal development of skeletal muscles and in microRNA (miRNA) misregulation observed in mouse models and patients with DM1. We identify multiple miRNAs sensitive to MBNL proteins insufficiency and reveal that many of them were postnatally regulated, which correlates with increases in the activity of these proteins during this process. In adult Mbnl1-knockout mice, miRNA expression exhibited an adult-to-newborn shift. We hypothesize that Mbnl1 deficiency influences miRNA levels through a combination of mechanisms. First, the absence of Mbnl1 protein results in alterations to the levels of pri-miRNAs. Second, MBNLs affect miRNA biogenesis by regulating the alternative splicing of miRNA primary transcripts. We propose that the expression of miR-23b, miR-27b and miR-24-1, produced from the same cluster, depends on the MBNL-sensitive inclusion of alternative exons containing miRNA sequences. Our findings suggest that MBNL sequestration in DM1 is partially responsible for altered miRNA activity. This study provides new insights into the biological roles and functions of MBNL proteins as regulators of miRNA expression in skeletal muscles.

DOI: https://doi.org/10.1093/nar/gkae774
bioRxiv. 2024 Aug 27. pii: 2024.08.27.607409. [Epub ahead of print]

A robust evaluation of TDP-43, poly GP, cellular pathology and behavior in a AAV-C9ORF72 (G4C2)66 mouse model.

Emily G Thompson, Olivia Spead, S Can Akerman, Carrie Curcio, Benjamin L Zaepfel, Erica R Kent, Thomas Philips, Balaji G Vijayakumar, Anna Zacco, Weibo Zhou, Guhan Nagappan, Jeffrey D Rothstein.

  The G4C2 hexanucleotide repeat expansion in C9ORF72 is the major genetic cause of both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9-ALS/FTD). Despite considerable efforts, the development of mouse models of C9-ALS/FTD useful for therapeutic development has proven challenging due to the intricate interplay of genetic and molecular factors underlying this neurodegenerative disorder, in addition to species differences. This study presents a robust investigation of the cellular pathophysiology and behavioral outcomes in a previously described AAV mouse model of C9-ALS expressing 66 G4C2 hexanucleotide repeats. Despite displaying key molecular ALS pathological markers including RNA foci, dipeptide repeat (DPR) protein aggregation, p62 positive stress granule formation as well as mild gliosis, the AAV-(G4C2)66 mouse model in this study exhibits negligible neuronal loss, no motor deficits, and functionally unimpaired TAR DNA-binding protein-43 (TDP-43). While our findings indicate and support that this is a robust and pharmacologically tractable model for investigating the molecular mechanisms and cellular consequences of (G4C2) repeat driven DPR pathology, it is not suitable for investigating the development of disease associated neurodegeneration, TDP-43 dysfunction, gliosis, and motor performance. Our findings underscore the complexity of ALS pathogenesis involving genetic mutations and protein dysregulation and highlight the need for more comprehensive model systems that reliably replicate the multifaceted cellular and behavioral aspects of C9-ALS.

Keywords:  Amyotrophic Lateral Sclerosis; C9orf72 repeat expansion; Dipeptide Repeats; GFAP; NfL; p62

DOI:  https://doi.org/10.1101/2024.08.27.607409
MedComm (2020). 2024 Sep;5(9): e712

Loss-of-function variants in RNA binding motif protein X-linked induce neuronal defects contributing to amyotrophic lateral sclerosis pathogenesis.

Di He, Xinyi He, Dongchao Shen, Liyang Liu, Xunzhe Yang, Meng Hao, Yi Wang, Yi Li, Qing Liu, Mingsheng Liu, Jiucun Wang, Xue Zhang, Liying Cui.

  Despite being one of the most prevalent RNA modifications, the role of N6-methyladenosine (m6A) in amyotrophic lateral sclerosis (ALS) remains ambiguous. In this investigation, we explore the contribution of genetic defects of m6A-related genes to ALS pathogenesis. We scrutinized the mutation landscape of m6A genes through a comprehensive analysis of whole-exome sequencing cohorts, encompassing 508 ALS patients and 1660 population-matched controls. Our findings reveal a noteworthy enrichment of RNA binding motif protein X-linked (RBMX) variants among ALS patients, with a significant correlation between pathogenic m6A variants and adverse clinical outcomes. Furthermore, Rbmx knockdown in NSC-34 cells overexpressing mutant TDP43Q331K results in cell death mediated by an augmented p53 response. Similarly, RBMX knockdown in ALS motor neurons derived from induced pluripotent stem cells (iPSCs) manifests morphological defects and activation of the p53 pathway. Transcriptional analysis using publicly available single-cell sequencing data from the primary motor cortex indicates that RBMX-regulated genes selectively influence excitatory neurons and exhibit enrichment in ALS-implicated pathways. Through integrated analyses, our study underscores the emerging roles played by RBMX in ALS, suggesting a potential nexus between the disease and dysregulated m6A-mediated mRNA metabolism.

Keywords:  ALS; RBMX; m6A modification; single‐cell sequencing; whole‐exome sequencing

DOI:  https://doi.org/10.1002/mco2.712
Medicine (Baltimore). 2024 May 31. 103(22): e38284

Prolonged loss of intercostal muscle mass and its predictors in COVID-19 patients: A retrospective study from tertiary hospital.

Byeong Ju Koo, Ho Cheol Choi, Hye Young Choi, Hwa Seon Shin, Jung Ho Won, Seok Jin Hong, Won Jeong Yang, Jae Kyeong Ahn, Mi Jung Park.

Sarcopenia is a contributing factor in the development of long-COVID syndrome. We aimed to investigate how intercostal muscle mass changes over 3 months compared to other chest wall muscles following COVID-19 infection, along with identifying factors contributing to intercostal muscle loss during follow-up. We retrospectively studied 110 COVID-19 patients, analyzing muscle masses in the intercostal, pectoralis, and thoracic 12th vertebra level (T12) on initial and follow-up CT scans. Muscle mass was quantitatively assessed using density histogram analysis. We calculated the muscle difference ratio (MDR) as the following formula: (initial muscle mass - follow-up muscle mass)/initial muscle mass. Patients were categorized into 2 groups: <3 months follow-up (n = 53) and ≥ 3 months follow-up (n = 57). We employed stepwise logistic regression, using intercostal MDR ≥ 25% in follow-up as an independent variable and age < 65 years, ventilator use, steroid use, follow-up > 3 months, hospital stay > 13 days, body mass index < 18.5 kg/m², and female gender as dependent variables. The loss of intercostal muscle was the most severe among the 3 chest wall muscles in the CT follow-up. Intercostal MDR was significantly higher in the ≥ 3 months follow-up group compared to the < 3 months group (32.5 ± 23.6% vs 19.0 ± 21.1%, P = .002). There were no significant differences in pectoralis MDR or T12 MDR between the 2 groups. Stepwise logistic regression identified steroid use (3.494 (1.419-8.604), P = .007) and a follow-up period > 3 months [3.006 (1.339-6.748), P = .008] as predictors of intercostal MDR ≥ 25%. The intercostal muscle wasting was profound compared to that in the pectoralis and T12 skeletal muscles in a follow-up CT scan, and the intercostal muscle wasting was further aggravated after 3 months of COVID-19 infection. The use of steroids and a follow-up period exceeding 3 months were significant predictors for ≥ 25% of intercostal muscle wasting in follow-up.

DOI: https://doi.org/10.1097/MD.0000000000038284
Cells. 2024 Sep 08. pii: 1504. [Epub ahead of print]13(17):

CCDC78: Unveiling the Function of a Novel Gene Associated with Hereditary Myopathy.

Diego Lopergolo, Gian Nicola Gallus, Giuseppe Pieraccini, Francesca Boscaro, Gianna Berti, Giovanni Serni, Nila Volpi, Patrizia Formichi, Silvia Bianchi, Denise Cassandrini, Vincenzo Sorrentino, Daniela Rossi, Filippo Maria Santorelli, Nicola De Stefano, Alessandro Malandrini.

  CCDC78 was identified as a novel candidate gene for autosomal dominant centronuclear myopathy-4 (CNM4) approximately ten years ago. However, to date, only one family has been described, and the function of CCDC78 remains unclear. Here, we analyze for the first time a family harboring a CCDC78 nonsense mutation to better understand the role of CCDC78 in muscle.
METHODS: We conducted a comprehensive histopathological analysis on muscle biopsies, including immunofluorescent assays to detect multiple sarcoplasmic proteins. We examined CCDC78 transcripts and protein using WB in CCDC78-mutated muscle tissue; these analyses were also performed on muscle, lymphocytes, and fibroblasts from healthy subjects. Subsequently, we conducted RT-qPCR and transcriptome profiling through RNA-seq to evaluate changes in gene expression associated with CCDC78 dysfunction in muscle. Lastly, coimmunoprecipitation (Co-Ip) assays and mass spectrometry (LC-MS/MS) studies were carried out on extracted muscle proteins from both healthy and mutated subjects.
RESULTS: The histopathological features in muscle showed novel histological hallmarks, which included areas of dilated and swollen sarcoplasmic reticulum (SR). We provided evidence of nonsense-mediated mRNA decay (NMD), identified the presence of novel CCDC78 transcripts in muscle and lymphocytes, and identified 1035 muscular differentially expressed genes, including several involved in the SR. Through the Co-Ip assays and LC-MS/MS studies, we demonstrated that CCDC78 interacts with two key SR proteins: SERCA1 and CASQ1. We also observed interactions with MYH1, ACTN2, and ACTA1.
CONCLUSIONS: Our findings provide insight, for the first time, into the interactors and possible role of CCDC78 in skeletal muscle, locating the protein in the SR. Furthermore, our data expand on the phenotype previously associated with CCDC78 mutations, indicating potential histopathological hallmarks of the disease in human muscle. Based on our data, we can consider CCDC78 as the causative gene for CNM4.

Keywords:  CCDC78; centronuclear myopathy-4; myopathy; sarcoplasmic reticulum

DOI:  https://doi.org/10.3390/cells13171504