Project description:Peripheral Artery Disease is caused by the restriction or occlusion of arteries supplying the leg. Better understanding of the molecular mechanisms underpinning tissue response to acute and chronic ischemia is urgently needed to improve therapeutic options. The aim of this study is understanding miR-210 regulation and role in a mouse model of hindlimb ischemia. To investigate miR-210 function, mice were injected with a miR-210 complementary LNA-oligonucleotide (anti-miR-210). Then, the left femoral artery was dissected in order to induce unilateral hindlimb ischemia. Mice were sacrified 3 days later and gene expression profiles of gastrocnemius muscles were obatained.
Project description:Peripheral Artery Disease is caused by the restriction or occlusion of arteries supplying the leg. Better understanding of the molecular mechanisms underpinning tissue response to acute and chronic ischemia is urgently needed to improve therapeutic options. The aim of this study is understanding miR-210 regulation and role in a mouse model of hindlimb ischemia.
Project description:Fine needle stimulation also known as acupuncture is a traditional Chinese medical practice which causes relief of pain. We demonstrated that it caused neovascularization and enhanced recovery of blood perfusion in a ischemic portion of skeletal muscle in rats with hindlimb ischemia. Therefore we evaluated the effect of fine needle stimulation on skeletal muscle at gene expression level Experiment Overall Design: With 0.14mm diameter stainless steel needle, a hundred pricks were applied in a 100 square mili-meter region on addductor portion of the left rat hindlimb. Right hindlimb was left intact as control. 24 hrs after fine needle stimulation, skeletal muscle sample was resected from adductor muscle of fine needle stimulated left hindlimb and non-stimulated right hindlimbs, respectively. Then gene expression analysis with microarray was conducted on each skelatal muscle sample.
Project description:To investigate the molecular mechanisms governing the transition of skeletal muscle from atrophy to compensatory regeneration and hypertrophy, we employed a mouse model involving hindlimb unloading and subsequent reloading, conducting a comprehensive analysis of global gene expression using RNA-sequencing (RNA-seq). Gastrocnemius muscle samples were obtained from three groups: control mice, mice subjected to 10 days of hindlimb unloading-induced muscle atrophy, and mice reintroduced to normal cage activity for 1 day following the unloading period (reloading).
Project description:Fine needle stimulation also known as acupuncture is a traditional Chinese medical practice which causes relief of pain. We demonstrated that it caused neovascularization and enhanced recovery of blood perfusion in a ischemic portion of skeletal muscle in rats with hindlimb ischemia. Therefore we evaluated the effect of fine needle stimulation on skeletal muscle at gene expression level Keywords: Evaluation of physical stimulation
Project description:Stimulation of the mouse hindlimb via the sciatic nerve was used to induce contractions for 4 hours to investigate acute muscle gene activation in a model of muscle phenotype conversion. Initial force production (1.6 + 0.1 g/g body weight) declined 45% within 10 min and was maintained for the remainder of the experiment. Force returned to initial levels upon completion of the study. An immediate-early growth response was present in the EDL (FOS, JUN, ATF3, MAFK) with a similar but attenuated pattern in the soleus. Transcript profiles showed decreased fast fiber specific mRNA (myosin heavy chains 2A, 2B; troponins T3, I; -tropomyosin, m-creatine kinase) and increased slow transcripts (myosin heavy chain slow/1, troponin C, tropomyosin 3) in the EDL. Histological analysis of the EDL revealed glycogen depletion without inflammatory cell infiltration or myofiber damage in stimulated vs. control muscles. Several fiber type specific transcription factors (EYA1, TEAD1, NFATc1 and c4, PPARG, PPARGC1 and β, BHLHB2) increased in the EDL along with transcription factors characteristic of embryogenesis (KLF4, SOX17, TCF15, PKNOX1, ELAV). No established in vivo satellite cell markers or the genes activated during our parallel studies of satellite cell proliferation in vitro (CYCLINS A2, B2, C, E1, MyoD) increased in the stimulated muscles. These data indicated that onset of fast to slow phenotype conversion occurred in the EDL within 4 hours of stimulation without satellite cell recruitment or muscle injury but was driven by phenotype specific transcription factors from resident fiber myonuclei including activation of nascent developmental transcriptional programs. Adult male Swiss Webster mice (30-35 g) were anesthetized, a bipolar electrode was implanted adjacent to the sciatic nerve and the hindlimb immobilized. The voltage-force relation was determined to establish supramaximal stimulation conditions and the length-tension relation was determined to set the resting length for maximum twitch tension. Contractions were induced by sciatic nerve stimulation (0.5 msec duration, 2-5 volts). The muscles were allowed to rest 15 minutes for full metabolic recovery at physiologic temperatures. Supramaximal stimulation was applied at a rate of 10 Hz for 4 hours. At the end of each experiment the soleus muscles were carefully dissected and flash frozen in liquid nitrogen for analysis of mRNA expression via microarray analysis. The contralateral, unstimulated Soleus provided a genetically matched, paired control for each specimen.
Project description:Divergent skeletal muscle phenotypes result from chronic resistance-type versus endurance-type contraction, reflecting the principle of training specificity. However, it is unclear whether there is a common set of genetic factors that influence skeletal muscle adaptation to disuse. Female rats were obtained from out-bred lines selectively bred from high responders to endurance training (HRT) or low responders to endurance training (LRT; n=6/group; generation 19). Both groups underwent 3 d of hindlimb immobilization to induce atrophy of the plantaris and soleus muscles prior to comparison to non-immobilization controls of the same genotype. RNA sequencing was performed to identify Gene Ontology Biological Processes with differential (LRT vs HRT) gene set enrichment. Running distance, determined well in advance of hindlimb immobilization, increased in response to aerobic training in HRT but not LRT. The atrophy response to hindlimb immobilization was exaggerated in LRT versus HRT. There were between-group differences for 140 processes in plantaris muscle and 118 processes in soleus muscle. In conclusion, low responders to aerobic endurance training exhibited exaggerated atrophy, and this was associated with differential gene expression. Thus, our findings suggest that genetic factors that underpin aerobic training maladaptation may also dysregulate the transcriptional activity of biological processes that contribute to adaptation to hindlimb immobilization.
Project description:Activation of the sympathetic nervous system causes pronounced metabolic changes that are mediated by multiple adrenergic receptor subtypes. Systemic treatment with β<sub>2-</sub>adrenergic receptor agonists results in multiple beneficial metabolic effects, including improved glucose homeostasis. To elucidate the underlying cellular and molecular mechanisms, we chronically treated wild-type mice and several newly developed mutant mouse strains with clenbuterol, a selective β<sub>2</sub>-adrenergic receptor agonist. Clenbuterol administration caused pronounced improvements in glucose homeostasis and prevented the metabolic deficits in mouse models of β-cell dysfunction and insulin resistance. Studies with skeletal muscle-specific mutant mice demonstrated that these metabolic improvements required activation of skeletal muscle β<sub>2</sub>-adrenergic receptors and the stimulatory G protein, G<sub>s</sub>. Unbiased transcriptomic and metabolomic analyses showed that chronic β<sub>2</sub>-adrenergic receptor stimulation caused metabolic reprogramming of skeletal muscle characterized by enhanced glucose utilization. These findings strongly suggest that agents targeting skeletal muscle metabolism by modulating β<sub>2</sub>-adrenergic receptor-dependent signaling pathways may prove beneficial as antidiabetic drugs.