Rat FBXO32 (F-box only protein 32) ELISA Kit

Muscle atrophy is a frequent complication of CKD, and exercise can attenuate the process. This study investigated the role of microRNA-23a (miR-23a) andmiR-27a in the regulation of muscle mass in mice with CKD. These miRs are located in a gene cluster that is regulated by the transcription factor NFAT. CKD mice expressed less miR-23a in muscle than controls, and resistance exercise (muscle overload) increased the levels of miR-23a and miR-27a in CKD mice. Injection of an adeno-associated virus encoding the miR-23a/27a/24-2 precursor RNA into the tibialis anterior muscles of normal and CKD mice led to increases in mature miR-23a and miR-27a but not miR-24-2 in the muscles of both cohorts. Overexpression of miR-23a/miR-27a in CKD mice attenuated muscle loss, improved grip strength, increased the phosphorylation of Akt and FoxO1, and decreased the activation of phosphatase and tensin homolog (PTEN) and FoxO1 and the expression of TRIM63/MuRF1 and FBXO32/atrogin-1 proteins. Provision of miR-23a/ miR-27a also reduced myostatin expression and downstreamSMAD-2/3 signaling, decreased activation of caspase-3 and -7, and increased the expression of markers of muscle regeneration. Lastly, in silico miR target analysis and luciferase reporter assays in primary satellite cells identified PTEN and caspase-7 as targets of miR-23a and FoxO1 as a target of miR-27a in muscle. These findings provide new insights about the roles of the miR-23a/27a-24-2 cluster in CKD-induced muscle atrophy in mice and suggest a mechanism by which exercise helps to maintain muscle mass.

Beta-hydroxy-beta-methylbutyrate (HMB), a leucine metabolite, enhances the gain of skeletal muscle mass by increasing protein synthesis or attenuating protein degradation or both. The aims of this study were to investigate the effect of HMB on molecular factors controlling skeletal muscle protein synthesis and degradation, as well as muscle contractile function, in fed and fasted conditions. Wistar rats were supplied daily with HMB (320 mg/kg body weight diluted in NaCl-0.9%) or vehicle only (control) by gavage for 28 days. After this period, some of the animals were subjected to a 24-h fasting, while others remained in the fed condition. The EDL muscle was then removed, weighed and used to evaluate the genes and proteins involved in protein synthesis (AKT/4E-BP1/S6) and degradation (Fbxo32 and Trim63). A sub-set of rats were used to measure in vivo muscle contractile function. HMB supplementation increased AKT phosphorylation during fasting (three-fold). In the fed condition, no differences were detected in atrogenes expression between control and HMB supplemented group; however, HMB supplementation did attenuate the fasting-induced increase in their expression levels. Fasting animals receiving HMB showed improved sustained tetanic contraction times (one-fold) and an increased muscle to tibia length ratio (1.3-fold), without any cross-sectional area changes. These results suggest that HMB supplementation under fasting conditions increases AKT phosphorylation and attenuates the increased of atrogenes expression, followed by a functional improvement and gain of skeletal muscle weight, suggesting that HMB protects skeletal muscle against the deleterious effects of fasting.