Project description:Skeletal muscle is the contractile tissue that distributes throughout body, with its functionally heterogeneous properties amongst muscles, which may relate to region specific pathology of muscle diseases. Here we found that homeobox (Hox) genes, key regulators of body-plan in the embryo, are region-specifically and robustly maintained as positional memory in both muscle and its associated stem cells named satellite cells in adult mice and humans. Although satellite cell function in adults was unaffected by genetic loss of Hoxa10 in muscle progenitors at the developmental stage, postnatal deletion of Hoxa10 in satellite cells led to genomic instability and mitosis abnormality, resulting in a remarkable decline in regenerative ability of muscles in a region-specific manner. Our results suggest that Hox-based positional memory is flexibly established during embryonic development and governs topographic function of stem cells in adult muscles once it is fixed, potentially influencing the region-specific weakness in muscle diseases
Project description:Skeletal muscle is contractile tissue distributed throughout the body with functionally heterogeneous properties that may relate to region-specific pathophysiology of muscle diseases. Recent studies revealed that muscle stem cells (satellite cells) are a functional heterogeneous population in different muscles, dependent not only on fiber-types but also on embryonic origin. Homeobox (Hox) genes are key regulators of the embryonic body plan. Here, we showed that Hox-A cluster genes are robustly maintained in adult muscles and their associated satellite cells of both mice and humans in a body region-specific manner, whose distribution almost recapitulates their embryonic origin. The region-specific expression of Hox genes was linked to DNA hypermethylation status of Hox-A locus. Importantly, Hox gene expression is a functional memory; Hoxa10 inactivation in satellite cells led to genomic instability and mitotic catastrophe, resulting in a decline in the regionally specific regenerative ability of muscles in mice, even though Hox paralogs are known to be often functionally redundant. Thus, our results demonstrate that the topographic Hox gene expression profile could be a geotagging molecular signature that reflects the anatomical location and embryonic history of resident muscle stem cells, potentially contributing to regionally specific regulations of adult skeletal muscles.
Project description:Purpose: During postnatal development the fetal skeletal muscle undergoes a rapid and dramatic transition to adult function through transcriptional and post-transcriptional mechanisms, including alternative splicing (AS) Methods:We performed RNA-seq for high-resolution analysis of transcriptome changes during postnatal mouse skeletal muscle development using RNA from gastrocnemius muscle from embryonic day 18.5, postnatal day 2 (PN2), PN14, PN28, adult (22 weeks). Results: We identified a novel role for AS in several cellular functions including calcium handling and membrane organization during postnatal skeletal muscle development. Furthermore, AS transitions within calcium handling genes are responsive to Celf1 and Mbnl1, RNA-binding proteins with developmentally regulated expression. Conclusions: We identified a novel role for AS in several functional categories during postnatal development including calcium handling, vesicular trafficking and cell junctions.
Project description:Fetal myogenesis and postnatal skeletal muscle hypertrophy in growing pigs are critical yet poorly understood processes. Global gene expression analyses will increase understanding of these processes by identifying key genes and pathways controlling skeletal muscle development. For this study, a pig 70-mer oligonucleotide microarray was used to identify differentially expressed genes in hind limb skeletal muscle of pigs at 60 days of gestation and 7 weeks of age. This oligonucleotide microarray experiment revealed 162 genes that were differentially expressed between 60 day fetal and 7 week postnatal samples. Relative real-time RT-PCR was used to confirm differential expression of three genes. This experiment identified genes exhibiting different developmental patterns of gene expression in pig skeletal muscle. Oligonucleotide microarrays used for this study consisted of 13,297 70-mer oligos (Pig Array-Ready Oligo Set v. 1.0 and Pig Oligo Extension Set v. 1.0, Qiagen, Inc., Valencia, CA) each spotted once on a single slide . Controls included 76 Arabidopsis thaliana gene spots, 17 beta tubulin spots, 17 glyceraldehyde-3-phosphate dehydrogenase spots, 85 heat shock protein gene spots, 69 ribosomal protein gene spots, 112 randomly generated negative control spots and 470 blanks. The oligonucleotide microarray was screened with samples obtained from pigs at 60 days of gestation and 7 weeks of age postnatal (n = 3 per age). Six oligonucleotide microarray slides were screened. All samples were used twice, labeled once with Cy3 and once with Cy5, and each 60 day gestation sample was randomly paired with two different 7 week postnatal samples.
Project description:Fetal myogenesis and postnatal skeletal muscle hypertrophy in growing pigs are critical yet poorly understood processes. Global gene expression analyses will increase understanding of these processes by identifying key genes and pathways controlling skeletal muscle development. For this study, a pig 70-mer oligonucleotide microarray was used to identify differentially expressed genes in hind limb skeletal muscle of pigs at 60 days of gestation and 7 weeks of age. This oligonucleotide microarray experiment revealed 162 genes that were differentially expressed between 60 day fetal and 7 week postnatal samples. Relative real-time RT-PCR was used to confirm differential expression of three genes. This experiment identified genes exhibiting different developmental patterns of gene expression in pig skeletal muscle. Keywords: developmental study
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: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. Muscle samples were isolated from the trunk of Pax3GFP/+ mice. After digestion, GFP cells were purified via FACS and process for RNA extraction and hybridization on Affymetrix microarrays (Affymetrix Mouse Genome 430 2.0 Arrays). The different ages selected for sample isolation were P1-P12-P28 (P, postnatal days), covering proliferant and quiescent satellite cells. The three stages were done in triplicate for P28 and 4 times for P1-P12, so 11 samples included in the microarray.