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: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 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.
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: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.
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:Satellite cells are the primary source of stem cells for skeletal muscle growth and regeneration. Since adult stem cell maintenance involves a fine balance between intrinsic and extrinsic mechanisms, we performed genome-wide chronological expression profiling to identify the transcriptomic changes involved during early postnatal growth till acquisition of satellite cell quiescence.
Project description:Epigenetic changes have been used to estimate chronological age across the lifespan, and some studies suggest that epigenetic "aging" clocks may already operate in developing tissue. To better understand the relationship between developmental stage and epigenetic age, we utilized the highly regular sequence of development found in the mammalian neural retina and a well-established epigenetic aging clock based on DNA methylation. Our results demonstrate that the epigenetic age of fetal retina is highly correlated with chronological age. We further establish that epigenetic aging progresses normally in vitro, suggesting that epigenetic aging is a property of individual tissues. This correlation is also retained in stem cell-derived retinal organoids, but is accelerated in individuals with Down's syndrome, a progeroid-like condition. Overall, our results suggest that epigenetic aging begins as early as a few weeks post-conception, in fetal tissues, and the mechanisms underlying the phenomenon of epigenetic aging might be studied in developing organs.