Biology subjects

Udd, B.

Publications and source records attributed to Udd, B..

5 recordsLinked to original sources

bioRxiv2026

Vorinostat (SAHA) alters the skeletal muscle differentiation program

Epigenetic regulation, particularly histone acetylation, plays a critical role in skeletal muscle differentiation by modulating gene expression programs without altering DNA sequence. Histone deacetylases (HDACs) tightly regulate myogenesis by controlling the timing of differentiation. Pharmacological inhibition of HDACs has shown context-dependent effects on muscle cells. We investigated the effects of 1 {micro}M SAHA (suberoylanilide hydroxamic acid) on C2C12 and L6 myoblasts during differentiation using morphological, immunofluorescence, transcriptomic, and proteomic analyses. SAHA delayed early differentiation, reducing myotube formation with partial recovery at later stages. Transcriptomic analysis revealed time-dependent changes in pathways related to cytoskeleton, cell cycle, and chromatin regulation. Proteomics showed increased mitochondrial metabolism and reduced cytoskeletal components in C2C12 cells, while L6 cells displayed alterations in muscle structural and extracellular matrix proteins. SAHA induces stage- and model-dependent reprogramming of myogenesis, highlighting the importance of timing and cellular context in HDAC-targeted therapies.

cell biology↗

bioRxiv2024

The inhibitory effects of Remodelin on murine myoblasts differentiation

Myoblasts differentiation is a highly regulated and complex process leading to the formation of fused and aligned mature myotubes. Growing interest in the role of epigenetics in muscle differentiation has highlighted epi-modulators as crucial regulators of this process. Our in vitro study aimed to explore the potential effects of the inhibition of the acetyltransferase Nat10 on myoblasts differentiation, by using Remodelin, a Nat10 selective inhibitor. We cultivated and differentiated murine C2C12 myoblasts on ultra-compliant gelatin substrates for up to 16 days and treated them with Remodelin. A combination of morphological analyses, confocal microscopy, transcriptomic profiling (RNA-seq), quantitative proteomics and metabolomics analyses was employed to assess the impact of Nat10 inhibition on myotube formation and maturation. To evaluate the reproducibility of Remodelin effects across myogenic systems and species, L6 rat myoblasts were included as a secondary comparative model. Remodelin treatment impaired myotube organization, alignment, and structural maturation in both C2C12 and L6 cells compared to untreated controls. In C2C12 cultures, Remodelin also abolished spontaneous myotube contractility. Intersection of transcriptomics and proteomics analyses confirmed that Remodelin effectively slowed myotube formation. Overall, these results indicate that Remodelin broadly affects the regulatory networks involved in skeletal muscle differentiation.

cell biology↗

bioRxiv2022

Differential Effects of Mutations of Popeye Domain Containing Proteins on Heteromeric Interaction and Membrane Trafficking

BackgroundThe Popeye domain containing (POPDC) genes encode sarcolemma-localised cAMP effector proteins. Mutations in BVES (POPDC1) and POPDC2 have been associated with limb-girdle muscular dystrophy and cardiac arrhythmia. Muscle biopsies of affected patients display impaired membrane trafficking of both POPDC isoforms. MethodsBiopsy material of patients carrying mutations in BVES were immunostained with POPDC antibodies. The interaction of POPDC proteins was investigated by co-precipitation, proximity ligation, bioluminescence resonance energy transfer and bimolecular fluorescence complementation. Site-directed mutagenesis was utilised to map the domains involved in protein interaction. FindingsPatients carrying a novel homozygous variant, BVES (c.547G>T, p.V183F) displayed only a skeletal muscle pathology and a mild impairment of membrane trafficking of both POPDC isoforms. This is in contrast to variants such as BVES p.Q153X or POPDC2 p.W188X, which were associated with a greater impairment of membrane trafficking. Co-transfection analysis in HEK293 cells revealed that POPDC proteins interact with each other through a helix-helix interface located at the C-terminus of the Popeye domain. Site-directed mutagenesis of an array of ultra-conserved hydrophobic residues demonstrated that some of them are required for membrane trafficking of the POPDC1-POPDC2 complex. InterpretationMutations in POPDC proteins that cause an impairment in membrane localisation affect POPDC complex formation while mutations which leave the protein interaction intact likely affect some other essential function of POPDC proteins. FundingThis study was funded by an EPSRC/British Heart Foundation co-funded Imperial Institute of Chemical Biology (ICB) Centre for Doctoral Training (CDT) PhD studentship (EP/S023518/1), a project grant of the British Heart Foundation (PG19/13/34247) and the Deutsche Forschungsgemeinschaft (DE1482/9-1). Research in ContextO_ST_ABSEvidence before this studyC_ST_ABSSeveral biallelic missense and nonsense variants in BVES (POPDC1) have been described and are associated with heart and skeletal muscle disease. Skeletal muscle biopsies of homozygous carriers of these variants display a loss of sarcolemmal localisation of POPDC1 and POPDC2. Added value of this studyWe demonstrate that POPDC1 and POPDC2 form a heteromeric complex and that complex formation is required for plasma membrane trafficking of POPDC proteins. Transfection of different disease variants in HEK293 cells replicates their defective membrane targeting observed in biopsy material. Structural modelling and site-directed mutagenesis identifies an interface of strongly conserved hydrophobic residues in POPDC proteins, which likely mediate the interaction of POPDC proteins. Implications of all the available evidenceThese data provide novel insight into the membrane targeting requirements of POPDC proteins. We recommend testing the membrane targeting properties of any novel variant in POPDC isoforms using a newly developed co-transfection assay in HEK293 cells to characterise its pathogenicity. Our novel insight into the requirement of heterodimerization for proper membrane targeting may also offer novel opportunities to treat patients carrying mutations in POPDC proteins.

genetics↗

bioRxiv2021

Comprehensive transcriptomic analysis shows disturbed calcium homeostasis and deregulation of T lymphocyte apoptosis in inclusion body myositis

ObjectiveInclusion body myositis (IBM) has an unclear molecular etiology due to the co-existence of characteristic cytotoxic T-cell activity and degeneration of muscle fibers. Using in-depth gene expression and splicing studies, we aimed at understanding the different components of the molecular pathomechanisms in IBM. MethodsWe performed RNA-seq on RNA extracted from skeletal muscle biopsies of clinically and histopathologically defined IBM (n=24), tibial muscular dystrophy (n=6), and histopathologically normal group (n=9). In a comprehensive transcriptomics analysis, we analyzed the differential gene expression, differential splicing and exon usage, downstream pathway analysis, and the interplay between coding and non-coding RNAs (micro RNAs and long non-coding RNAs). ResultsWe observe dysregulation of genes involved in calcium homeostasis, particularly affecting the T-cell activity and regulation, causing disturbed Ca2+ induced apoptotic pathway of T cells in IBM muscles. Additionally, LCK/p56, which is an essential gene in regulating the fate of T-cell apoptosis, shows altered expression and splicing usage in IBM muscles InterpretationOur analysis provides a novel understanding of the molecular mechanisms in IBM by showing a detailed dysregulation of genes involved in calcium homeostasis and its effect on T-cell functioning in IBM muscles. Loss of T-cell regulation is hypothesized to be involved in the consistent observation of no response to immune therapies in IBM patients. Our results show that loss of apoptotic control of cytotoxic T cells could indeed be one component of their abnormal cytolytic activity in IBM muscles.

neuroscience↗

bioRxiv2021

Biallelic loss-of-function OBSCN variants predispose individuals to severe, recurrent rhabdomyolysis

Rhabdomyolysis is the acute breakdown of skeletal myofibres in response to an initiating factor, most commonly toxins and over exertion. A variety of genetic disorders predispose to rhabdomyolysis through different pathogenic mechanisms, particularly in patients with recurrent episodes. However, the majority of cases remain without a genetic diagnosis. Here we present six patients who presented with severe and recurrent rhabdomyolysis, usually with onset in the teenage years; other features included a history of myalgia and muscle cramps. We identified ten bi-allelic loss-of-function variants in the gene encoding obscurin (OBSCN) co-segregating with disease. We show reduced expression of OBSCN and loss of obscurin protein in patient muscle. Obscurin is proposed to be involved in SR function and Ca2+ handling. Patient cultured myoblasts appear more susceptible to starvation as evidenced by a greater decreased in SR Ca2+ content compared to control myoblasts. This likely reflects a lower efficiency when pumping Ca2+ back into the SR and/or a decrease in Ca2+ SR storage ability when metabolism is diminished. OSBCN variants have previously been associated with cardiomyopathies. None of the patients presented with a cardiomyopathy and cardiac examinations were normal in all cases in which cardiac function was assessed. There was also no history of cardiomyopathy in first degree relatives, in particular in any of the carrier parents. This cohort is relatively young, thus follow-up studies and the identification of additional cases with bi-allelic null OBSCN variants will further delineate OBSCN-related disease and the clinical course of disease.

genetics↗