Project description:Utilizing glycerol intramuscular injections in M. musculus provide a models of skeletal muscle damage followed by skeletal muscle regeneration. In particular, glycerol-induced muscle injury triggers accute activation of skeletal muscle stem cells, called satellite cells. However, aging dramatically impairs the regenerative capacity of satellite cells. We characterized genome-wide expression profiles of young and old satellite cells in the non-proliferative and activated state, freshly isolated to non-injured or damaged muscles, respectively. Our goal was to uncover new regulatory signaling specific to satellite cells entry into the activation and myogenic program that are affected with age. Satellite cells were isolated in either quiescent / non-proliferative or activated state from uninjured or 3 days after glycerol-induced injury of tibialis anterior, gastrocnemius and quadriceps, respectively. Young (2-4 months old) and old (20-24 months old) wildtype C57BL/6J male were used, with five to six biological replicates per group.
Project description:Skeletal muscle is a post-mitotic tissue that exhibits an extremely low turnover in the absence of disease or injury. At the same time, muscle possesses remarkable regenerative capacity mediated by satellite cells (SCs) that reside in close association with individual myofibers, underneath the fiber’s basal lamina. Consistent with the low turnover of the muscle, SCs in adult animals are mitotically quiescent and therefore provide an excellent model to study stem cell quiescence. As an organism grows older, the resident stem cells are exposed to a deteriorating environment and experience chronological aging. In stem cells with high turnover, the effects of chronological aging are superimposed upon the effects of the replicative aging that results from DNA replication and cell division. On the contrary, SCs experience minimal replicative aging due to their low turnover. They are thus a good model to study the consequence of chronological aging of quiescent stem cells. We performed microarray analysis of quiescent and activated SCs from both young and aged mice to understand the global gene expression profile underlying stem cell properties such as quiecence and self-renewal, and to understand how the transcriptome of a quiescent stem cell pouplation changes with age. VCAM+/CD31-/CD45-/Sca1- quiescent satellite cells (QSCs) were isolated by FACS from hindlimb muscle of uninjured 2-3- or 22-24-month old mice. Activated satellite cells (ASCs) were isolated from hindlimb muscles of BaCl2-injured mice of the same age 36, 60 and 84 hours after injury using the same cell surface marker combination. YFP-expressing cells were isolated from 2-3-month old Pax7CreER/+; ROSA26eYFP/+ mice in which satellite cells are labeled geneticall by YFP expression. Total RNA was extracted from cells with the Trizol reagent according to manufacturer's instructions. RNA was then processed and assayed with Affymetrix Mouse Gene 1.0 ST arrays.
Project description:Utilizing glycerol intramuscular injections in M. musculus provide a models of skeletal muscle damage followed by skeletal muscle regeneration. In particular, glycerol-induced muscle injury triggers accute activation of skeletal muscle stem cells, called satellite cells. However, aging dramatically impairs the regenerative capacity of satellite cells. We characterized genome-wide expression profiles of young and old satellite cells in the non-proliferative and activated state, freshly isolated to non-injured or damaged muscles, respectively. Our goal was to uncover new regulatory signaling specific to satellite cells entry into the activation and myogenic program that are affected with age.
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from Mus musculus tissues (Heart, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:Skeletal muscle is a post-mitotic tissue that exhibits an extremely low turnover in the absence of disease or injury. At the same time, muscle possesses remarkable regenerative capacity mediated by satellite cells (SCs) that reside in close association with individual myofibers, underneath the fiberM-bM-^@M-^Ys basal lamina. Consistent with the low turnover of the muscle, SCs in adult animals are mitotically quiescent and therefore provide an excellent model to study stem cell quiescence. As an organism grows older, the resident stem cells are exposed to a deteriorating environment and experience chronological aging. In stem cells with high turnover, the effects of chronological aging are superimposed upon the effects of the replicative aging that results from DNA replication and cell division. On the contrary, SCs experience minimal replicative aging due to their low turnover. They are thus a good model to study the consequence of chronological aging of quiescent stem cells. We have developed an isolation protocol to selectively enrich SCs by FACS from adult mice and applied the ChIP-seq technology to obtain H3K4me3, H3K27me3 and H3K36me3 from quiescent and activated SCs from young mice and from quiescent SCs from old mice. Our analysis aims to understand the chromatin features underlying stem cell properties such as quiecence and lineage-potency, and to understand how the chromatin structure of a quiescent stem cell pouplation changes with age. VCAM+/CD31-/CD45-/Sca1- quiescent satellite cells (QSCs) were isolated by FACS from hindlimb muscle of uninjured 2-3- or 22-24-month old mice and processed for ChIP-seq.
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from seven Mus musculus tissues (Heart, Brain, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:Skeletal muscle holds an intrinsic capability of growth and regeneration both in physiological conditions and in case of injury. Chronic muscle illnesses, generally caused by genetic and acquired factors, lead to deconditioning of the skeletal muscle structure and function, and are associated with a significant loss in muscle mass. At the same time, progressive muscle wasting is a hallmark of aging. Given the paracrine properties of myogenic stem cells, extracellular vesicle-derived signals have been studied for their potential implication in both the pathogenesis of degenerative neuromuscular diseases and as a possible therapeutic target. In this study, we screened the content of extracellular vesicles from animal models of muscle hypertrophy and muscle wasting associated with chronic disease and aging. Analysis of the transcriptome, protein cargo and microRNAs (miRNAs) allowed us to identify a hypertrophic miRNA signature amenable for targeting muscle wasting, consisting of miR-1 and miR-208a. We tested this signature among others in vitro on mesoangioblasts (MABs), vessel-associated adult stem cells, and we observed an increase in the efficiency of myogenic differentiation. Furthermore, injections of miRNA-treated MABs in aged mice resulted in an improvement in skeletal muscle features, such as muscle weight, strength and cross-sectional area compared to controls. Overall, we provide evidence that the extracellular vesicle-derived miRNA signature we identified enhances the myogenic potential of myogenic stem cells.
Project description:Muscle stem cells (MuSCs) are required for muscle regeneration. In resting muscles, MuSCs are kept in quiescence. After injury, MuSCs undergo rapid activation, proliferation and differentiation to repair damaged muscles. Age-associated impairments in stem cell functions correlate with a decline in somatic tissue regeneration capacity during aging. However, the mechanisms underlying the molecular regulation of adult stem cell aging remain elusive. Here, we obtained quisecent MuSCs from young, old, geriatric mice for high resolution mass spectrometry Bruker timsTOF Pro. By comparison of young proteome to old MuSCs proteome or geriatric MuSC proteome, we identified the pathways that are differentially during aging.
Project description:MicroRNAs (miRNAs) are important in the regulation of many biological processes including muscle development. However, little is known regarding miRNA regulation of muscle regeneration. In mature murine tibialis anterior muscle following injury, 298 miRNAs were significantly changed during the time course of muscle regeneration including 86 that were altered greater than 10-fold as compared to uninjured muscle. Temporal miRNA expression patterns were identified and included inflammation-related miRNAs (miR-223 and -147) that increased immediately after injury; this pattern contrasted to that of mature muscle-specific miRNAs (miR-1, -133a and -499) that were abruptly decreased following injury and then up-regulated in later regenerative events. Another cluster of miRNAs were transiently increased in the early days of muscle regeneration. This included miR-351, a miRNA that was also transiently expressed during myogenic progenitor cell (MPC) differentiation in vitro. Based on computational predictions, further studies demonstrated that E2f3 was a target of miR-351 in myoblasts. Moreover, knockdown of miR-351 expression inhibited MPC proliferation and promoted apoptosis during MPC differentiation, whereas miR-351 overexpression protected MPC from apoptosis during differentiation. Collectively, these observations suggest that miR-351 is involved in both the maintenance of MPC proliferation and the transition of MPC into differentiated myotubes. Thus, a novel, time-dependent sequence of molecular events during skeletal muscle regeneration has been identified, i.e., miR-351 inhibits E2f3 expression, a key regulator of cell cycle progression and proliferation, and promotes MPC proliferation and protects early differentiating MPC from apoptosis, important events in the hostile tissue environment after acute muscle injury. Skeletal muscles are damaged and repaired repeatedly throughout life. Muscle regeneration maintains locomotor function during aging and delays the appearance of clinical symptoms in neuromuscular diseases, such as Duchenne muscular dystrophy. The capacity for skeletal muscle growth and regeneration is conferred by satellite cells located between the basal lamina and the sarcolemma of mature myofibers. Upon injury, satellite cells reenter the cell cycle, proliferate, and then exit the cell cycle either to renew the quiescent satellite cell pool or to differentiate into mature myofibers. Despite recent advances, genes involved in these processes are still largely unknown. Understanding the molecular mechanisms that regulate satellite cell activities could promote development of novel countermeasures to enhance muscle regeneration that is compromised by diseases or aging. Using a muscle injury mouse model, we profiled miRNA expression during muscle regeneration.