Biology subjects

Lynch, G. S.

Publications and source records attributed to Lynch, G. S..

6 recordsLinked to original sources

bioRxiv2026

Engineering in vitro models of skeletal muscle with neuromuscular junctions using hierarchical micro-nano biomaterials: Cooperative effect of adhesion ligand nanoclustering and surface anisotropy

Robust development of in vitro mature skeletal muscle with functional neuromuscular junctions is an unmet challenge that must be addressed for advances in skeletal muscle tissue engineering and for the development of skeletal muscle tissue models for disease modelling and drug discovery. Herein, we developed hierarchical, anisotropic biomaterials that induced early maturation of more mature myotubes and the development of neuromuscular junctions (NMJs) during co-culture with motor neurons. We accomplished this by creating micro-nano biomaterial interfaces that presented nanoclusters of integrin-binding ligands to promote mechanotransduction on the surface of aligned electrospun microfibers. Controlling surface topography and nanoscale ligand clustering led to 1.5 to 2.5-fold increases in myoblast proliferation, myotube formation, elongation, and alignment; resulting in spontaneous twitching; and enhanced myotube-neuron connections, including increasing acetylcholine receptor clustering, neurite branching, and myotube contraction compared to control surfaces. These findings highlight the importance of tailoring adhesive peptide distribution and presentation for the in vitro development of NMJs and synaptic organization. This approach offers a valuable platform for fundamental research on muscle development and neuromuscular diseases, paving the way for improved skeletal muscle tissue engineering and drug screening strategies.

bioengineering↗

bioRxiv2026

Changing the Fate of Dystrophin-Deficient Myoblasts via Hetero ligand Nanoclusters on Biomaterial Surface: Effects of Integrin-Syndecan or Dystroglycan Crosstalk

Engineering skeletal muscle tissue regeneration, particularly in dystrophin-deficient muscles is dependent on facilitating myogenesis and recovery of myotube structure and function, which can be challenging due to compromised cell-extracellular matrix (ECM) interactions. The current study explored the potential impact of enhancing dystrophin-associated protein complex and focal adhesion formation and the interaction with associated target receptors to improve cellular response in both normal and Duchenne muscular dystrophy (Dmd) mutant myoblasts. This was achieved by multivalent dual ligands functionalization of RAFT-synthesized copolymer with fibronectin- and laminin-derived adhesion peptides (RGD, AG73, and A2G80) and their clustering at the biointerface. Our findings demonstrated the synergistic effect of integrin-syndecan/dystroglycan engagement and their clustering on enhancing myoblast adhesion, proliferation, and differentiation, partially overcoming the deficits caused by loss of dystrophin. Furthermore, enhanced focal adhesion formation and elevated receptor localization, particularly dystroglycan, at the sarcolemma were associated with improved structural organization, mechanical stability, and neuromuscular connectivity of myotubes. These results suggest a novel insight into harnessing next-generation molecularly engineered biomaterials with robust interaction with cells mechanosensors for advancing skeletal muscle tissue engineering, offering potential applications in the regeneration of dystrophic muscle and the development of neuromuscular disease models for drug testing. O_FIG O_LINKSMALLFIG WIDTH=174 HEIGHT=200 SRC="FIGDIR/small/717576v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@16c6b87org.highwire.dtl.DTLVardef@107a84borg.highwire.dtl.DTLVardef@1b9e4ddorg.highwire.dtl.DTLVardef@160a9a7_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract/ToCC_FLOATNO Current work developed molecularly engineered biomaterial surfaces with nanoscale clustering of integrin-, syndecan-, and/or dystroglycan-binding peptides for skeletal muscle tissue regeneration. By controlling peptide distribution and type at the biointerface, cell adhesion, proliferation, and differentiation were modulated in dystrophin-deficient myoblasts. Accordingly, the results demonstrated significant improvement in myotube structural organization, mechanical stiffness, and their innervation in response to heteronanoclusters. C_FIG

bioengineering↗

bioRxiv2023

Metabolism regulates muscle stem cell self-renewal by connecting the microenvironment and histone acetylation

Skeletal muscle contains a resident population of somatic stem cells capable of both self-renewal and differentiation. The signals that regulate this important decision have yet to be fully elucidated. Here we use metabolomics and mass spectrometry imaging (MSI) to identity a state of localized hyperglycaemia following skeletal muscle injury. We show that committed muscle progenitor cells exhibit an enrichment of glycolytic and TCA cycle genes and that extracellular monosaccharide availability regulates intracellular citrate levels and global histone acetylation. Muscle stem cells exposed to a reduced (or altered) monosaccharide environment demonstrate reduced global histone acetylation and transcription of myogenic determination factors (including myod1). Importantly, reduced monosaccharide availability was linked directly to increased rates of asymmetric division and muscle stem cell self-renewal in regenerating skeletal muscle. Our results reveal an important role for the extracellular metabolic environment in the decision to undergo self-renewal or myogenic commitment during skeletal muscle regeneration.

cell biology↗

bioRxiv2023

Mitochondrial fusion and altered beta-oxidation drive muscle wasting in a Drosophila cachexia model

Cancer cachexia is a tumour-induced wasting syndrome, characterised by extreme loss of skeletal muscle. Defective mitochondria can contribute to muscle wasting; however, the underlying mechanisms remain unclear. Using a Drosophila larval model of cancer cachexia, we observed enlarged and dysfunctional muscle mitochondria. Morphological changes were accompanied by upregulation of beta-oxidation proteins and depletion of muscle glycogen and lipid stores. Muscle lipid stores were also decreased in Colon-26 adenocarcinoma mouse muscle samples, and expression of the beta-oxidation gene CPT1A was negatively associated with muscle quality in cachectic patients. Mechanistically, mitochondrial defects result from reduced muscle insulin signalling, downstream of tumour-secreted insulin growth factor binding protein (IGFBP) homolog ImpL2. Strikingly, muscle-specific inhibition of Forkhead box O (FOXO), mitochondrial fusion, or beta-oxidation in tumour-bearing animals preserved muscle integrity. Finally, dietary supplementation with nicotinamide or lipids, improved muscle health in tumour-bearing animals. Overall, our work demonstrates that muscle FOXO, mitochondria dynamics/beta-oxidation and lipid utilisation are key regulators of muscle wasting in cancer cachexia.

developmental biology↗

bioRxiv2022

Alpha kinase 3 signaling at the M-band maintains sarcomere integrity and proteostasis in striated muscle.

Pathogenic variants in alpha kinase 3 (ALPK3) cause cardiomyopathy and musculoskeletal disease. How ALPK3 mutations result in disease remains unclear because little is known about this atypical kinase. Using a suite of engineered human pluripotent stem cells (hPSCs) we show that ALPK3 localizes to the M-Band of the sarcomere. ALPK3 deficiency disrupted sarcomeric organization and calcium kinetics in hPSC-derived cardiomyocytes and reduced force generation in cardiac organoids. Phosphoproteomic profiling identified ALPK3-dependant phospho-peptides that were enriched for sarcomeric components of the M-band and the ubiquitin-binding protein SQSTM1. Analysis of the ALPK3 interactome confirmed binding to M-band proteins including SQSTM1. Importantly, in hPSC-derived cardiomyocytes modeling ALPK3 deficiency and cardiomyopathic ALPK3 mutations, sarcomeric organization and M-band localization ofSQSTM1 were abnormal. These data suggest ALPK3 has an integral role in maintaining sarcomere integrity and proteostasis in striated muscle. We propose this mechanism may underly disease pathogenesis in patients with ALPK3 variants.

cell biology↗

bioRxiv2020

Comprehensive characterization of single cell full-length isoforms in human and mouse with long-read sequencing

Alternative splicing shapes the phenotype of cells in development and disease. Long-read RNA-sequencing recovers full-length transcripts but has limited throughput at the single-cell level. Here we developed single-cell full-length transcript sequencing by sampling (FLT-seq), together with the computational pipeline FLAMES to overcome these issues and perform isoform discovery and quantification, splicing analysis and mutation detection in single cells. With FLT-seq and FLAMES, we performed the first comprehensive characterization of the full-length isoform landscape in single cells of different types and species and identified thousands of unannotated isoforms. We found conserved functional modules that were enriched for alternative transcript usage in different cell populations, including ribosome biogenesis and mRNA splicing. Analysis at the transcript-level allowed data integration with scATAC-seq on individual promoters, improved correlation with protein expression data and linked mutations known to confer drug resistance to transcriptome heterogeneity. Our methods reveal previously unseen isoform complexity and provide a better framework for multi-omics data integration.

genomics↗