Project description:Skeletal muscle dysfunction in survivors of pneumonia is a major cause of lasting morbidity that disproportionately affects older individuals. We found that skeletal muscle recovery was impaired in aged compared with young mice after influenza A virus-induced pneumonia. In young mice, recovery of muscle loss was associated with expansion of tissue-resident skeletal muscle macrophages and downregulation of MHC II expression, followed by a proliferation of muscle satellite cells. These findings were absent in aged mice and in mice deficient in Cx3cr1. Transcriptomic profiling of tissue-resident skeletal muscle macrophages from aged compared with young mice showed downregulation of pathways associated with phagocytosis and proteostasis, and persistent upregulation of inflammatory pathways. Consistently, skeletal muscle macrophages from aged mice failed to downregulate MHCII expression during recovery from influenza A virus induced pneumonia and showed impaired phagocytic function in vitro. Like aged animals, mice deficient in the phagocytic receptor Mertk showed no macrophage expansion, MHCII downregulation or satellite cell proliferation and failed to recover skeletal muscle function after influenza A pneumonia. Our data suggest that a loss of phagocytic function in a CX3CR1+ tissue-resident skeletal muscle macrophage population in aged mice precludes satellite cell proliferation and recovery of skeletal muscle function after influenza A pneumonia.
Project description:Our laboratory wanted to define the transcription profile of aged skeletal muscle. For this reason, we performed a triplicate microarray study on young (3 weeks) and aged (24 months) gatrocnemius muscle from wild-type C57B16 Mice Keywords: other
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: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:Our laboratory wanted to define the transcription profile of aged skeletal muscle. For this reason, we performed a triplicate microarray study on young (3 weeks) and aged (24 months) gatrocnemius muscle from wild-type C57B16 Mice Keywords: other this experiment include 2 samples and 6 replicates
Project description:Skeletal muscle atrophy is one of the critical issues which elderly people face. The precise mechanism underlying muscle atrophy during aging is not fully understood. In order to identify miRNA whose expression is changed in age-associated muscle atrophy, we performed miRNA expression profiling of skeletal muscles in young and aged rats. Microarray analysis revealed differential miRNA expression in EDL and soleus muscles of aged rats compared with those of young rats. We next investigated whether the age-associated changes of miRNA expression observed in rats were recapitulated in mice and found that the expression level of miR-206 in EDL muscle and that of miR-196a in EDL and soleus muscles were respectively higher and lower in aged rodents than in young rodents. In mouse C2C12 myoblasts and myotubes, introduction of miR-196a decreased the protein level of Forkhead-box transcription factor Foxo1, a known target of miR-196a, indicating that miR-196a may regulate Foxo1 expression also in skeletal muscles. Furthermore, miR-196a overexpression exacerbated cell death caused by an exposure to hydrogen peroxide. Lastly, we demonstrated that expression of Foxo1 was elevated in EDL and soleus muscles of aged mice compared with those of young mice. These results suggest that miRNAs are involved in skeletal muscle atrophy during aging and that decreased miR-196a expression may protect skeletal muscle cells from oxidative stress in part through induction of Foxo1.
Project description:Sarcopenia is the age-induced, progressive loss of skeletal muscle mass and function, which is accompanied by reduced muscle performance. Individuals with sarcopenia often become bedridden or dependent on a wheelchair, leading to decreased quality of life. In this study, to better understand changes in skeletal muscle during sarcopenia, we performed a microarray analysis of skeletal muscle in young (13-week-old) and aged (26-month-old) mice. The microarray data shows that expression of the enzymes related to glucose and polyamine metabolism were decreased in aged mice compared with young mice.
Project description:In this study, we investigated signaling pathways in Skeletal muscle precursors that are altered with aging and age-related deficits in muscle regenerative potential. We performed fluorescence activated cell sorting (FACS) to obtain highly purified skeletal muscle satellite cells from young, middle-aged and old mice. Parabiosis experiments indicate that impaired regeneration in aged mice is reversible by exposure to a young circulation, suggesting that young blood contains humoral "rejuvenating" factors that can restore regenerative function. Here, we demonstrate that the circulating protein growth differentiation factor 11 (GDF11) is a rejuvenating factor for skeletal muscle. Supplementation of systemic GDF11 levels, which normally decline with age, by heterochronic parabiosis or systemic delivery of recombinant protein, reversed functional impairments and restored genomic integrity in aged muscle stem cells (satellite cells). Increased GDF11 levels in aged mice also improved muscle structural and functional features and increased strength and endurance exercise capacity. These data indicate that GDF11 systemically regulates muscle aging and may be therapeutically useful for reversing age-related skeletal muscle and stem cell dysfunction. We used Affymetrix Mouse Genome array to identify global transcriptional changes associated with age in skeletal muscle precursors.
Project description:The adaptation of regimented exercise in skeletal muscle including muscular hypertrophy and enhanced strength decline significantly with aging. Transcriptome analysis following RNA sequencing reveals extensive activation of hypoxia-related genes in young exercised mice versus the sedentary, but absent in aged exercised mice. Particularly, less expression of aryl hydrocarbon receptor translocator (ARNT) was observed in response to exercise in aged mice. Young mice underwent skeletal muscle-specific knockout of ARNT (ARNT mKO) obtain deficient benefit from exercise resembling the aged mice. The deletion of ARNT associated with decreased expression of Notch1 intracellular domain(N1ICD) impair muscle hypertrophy and regeneration. Administration of ML228, a systematic agonist of ARNT, rescued skeletal muscle adaptabilities in old mice, which was suppressed by administrating N1ICD inhibitor(DAPT). These results suggest that the loss of skeletal muscle ARNT is partially responsible for diminished response to exercise in aging and activation of hypoxia signaling holds promise for rescuing the adaptability in aged muscle.