Project description:We report on the single cell RNA sequencing of genetically identified adult, neonatal, and embryonic proprioceptors. High depth sequencing data was acquired for all developmental time points using plate-seq. For adult proprioceptors, bioinformatics analysis identified five molecularly distinct subsets. At least two of these subsets have been validated to correspond to group Ia muscle spindle afferents and group Ib GTO afferents, respectively.
Project description:We performed single cell RNA sequencing analysis of human iPSC-derived skeletal muscle organoids at 12 week post differentiation stage.
Project description:Skeletal muscle is a key tissue in human aging, which affects different muscle fiber types unequally. We developed a highly sensitive single muscle fiber proteomics workflow to study human aging and show that the senescence of slow and fast muscle fibers is characterized by diverging metabolic and protein quality control adaptations. Whereas mitochondrial content declines with aging in both fiber types, glycolysis and glycogen metabolism are upregulated in slow but downregulated in fast muscle fibers. Aging mitochondria decrease expression of the redox enzyme monoamine oxidase A. Slow fibers upregulate a subset of actin and myosin chaperones, whereas an opposite change happens in fast fibers. These changes in metabolism and sarcomere quality control may be related to the ability of slow, but not fast, muscle fibers to maintain their mass during aging. We conclude that single muscle fiber analysis by proteomics can elucidate pathophysiology in a sub-type specific manner.
Project description:C18ORF25 is a homolog of Arkadia (RNF111), an E3 ubiquitin ligase with SUMO-interaction motifs (SIMs) (PMID: 31417085). However, C18ORF25 lacks the entire C-terminal RING domain of RNF111 which is required for ubiquitin binding suggesting it lacks ubiquitination activity and may therefore act as an adaptor or signalling scaffold (PMID: 26283374). We have previously shown that mice lacking C18Orf25 throughout the entire body have increased adiposity, decreased lean mass, lower exercise capacity and significantly reduced ex vivo skeletal muscle force production (PMID: 35882232). Skeletal muscle isolated from C18Orf25 knockout (KO) mice have reduced cAMP-dependent protein kinase A (PKA) levels, and reduced phosphorylation of several contractile proteins and proteins involved in calcium handling. Furthermore, analysis of single muscle fibres from C18Orf25 KO mice revealed impaired SR calcium cycling in fast-twitch fibres only (PMID: 35882232). Hence, we investigated these mechanisms by developing an integrated single-fibre physiology and single-fibre proteomic platform. The platform enabled us to identify hundreds of novel phenotype:protein correlations. The analysis also enabled us to identify proteome differences specifically in FT fibres following loss of C18ORF25. Taken together, our data suggest C18ORF25 is likely a multi-functional protein with several underlying mechanisms contributing to skeletal muscle physiology.
Project description:This study aims to characterize the diversity of cell types in human skeletal muscle across age using two complementary technologies: single-cell and single-nucleus sequencing, which provide a comprehensive coverage of cell types in the muscle. We leveraged the aforementioned datasets to study change in cell type composition and gene expression between young (n= 8, approx. 20-40 yrs) and old (n = 9, approx. 60-80 yrs) adults, highlighting changes in the major skeletal muscle compartments, muscle satellite cells, myofiber and muscle microenvironment including stromal, immune and vascular cell types. Additionally, we generated a complementary mouse muscle aging dataset by profiling hindlimb muscles from young (n = 5, 3 months) versus old mice (n = 3, 19 months), using single-cell and single-nucleus sequencing for comparison.
Project description:The proprioceptive system is essential for the control of coordinated movement, posture and skeletal integrity. The sense of proprioception is produced in the brain using peripheral sensory input from receptors such as the muscle spindle, which detects changes in the length of skeletal muscles. Despite its importance, the molecular composition of the muscle spindle is largely unknown. In this study, we generated comprehensive transcriptomic and proteomic datasets of the entire muscle spindle. We then associated differentially expressed genes with the various tissues composing the spindle using bioinformatic analysis. Immunostaining verified these predictions, thus establishing new markers for the different spindle tissues. Utilizing these markers, we identified the differentiation stages the spindle capsule cells undergo during development. Together, these findings provide comprehensive molecular characterization of the intact spindle as well as new tools to study its development and function in health and disease.
Project description:Single cell RNA-sequencing was used to analyze the cellular heterogeneity of mononucleated, non-myofiber cell populations and their transcriptional states in post-injury skeletal muscle
Project description:Background: Skeletal muscle myocytes have evolved into slow and fast-twitch types. These types are functionally distinct as a result of differential gene and protein expression. However, an understanding of the complexity of gene and protein variation between myofibers is unknown. Methods: We performed deep, whole cell, single cell RNA-seq on intact and fragments of skeletal myocytes from the mouse flexor digitorum brevis muscle. We compared the genomic expression data of 171 of these cells with two human proteomic datasets. The first was a spatial proteomics survey of mosaic patterns of protein expression utilizing the Human Protein Atlas (HPA) and the HPASubC tool. The second was a mass-spectrometry (MS) derived proteomic dataset of single human muscle fibers. Immunohistochemistry and RNA-ISH were used to understand variable expression. Results: scRNA-seq identified three distinct clusters of myocytes (a slow/fast 2A cluster and two fast 2X clusters). Utilizing 1,605 mosaic patterned proteins from visual proteomics, and 596 differentially expressed proteins by MS methods, we explore this fast 2X division. Only 36 genes/proteins were mosaic across all three studies, of which nine are newly described as variable between fast/slow twitch myofibers. An additional 414 genes/proteins were identified by two methods. Immunohistochemistry and RNA-ISH generally validated variable expression across methods presumably due to species-related differences. Conclusions: In this first integrated proteogenomic analysis of mature skeletal muscle myocytes we validate the main fiber types and greatly expand the known repertoire of twitch-type specific genes/proteins. We also demonstrate the importance of integrating genomic and proteomic datasets.