Chronic kidney disease induces autophagy leading to dysfunction of mitochondria in skeletal muscle

This study examines whether autophagy-mediated proteolysis contributes to CKD-induced muscle wasting. We tested autophagy in the muscle of CKD mice with plantaris muscle overloading to mimic resistance exercise or with acupuncture plus low-frequency electrical stimulation (Acu/LFES) treatment. In CKD muscle, Bnip3, Beclin-1, and LC3II mRNAs and proteins were increased compared with those in control muscle, indicating autophagosome-lysosome formation induction. Acu/LFES suppressed the CKD-induced upregulation of autophagy. However, overloading increased autophagy-related proteins in normal and CKD muscle. Serum from uremic mice induces autophagy formation but did not increase the myosin degradation or actin break down in cultured muscle satellite cells. We examined mitochondrial biogenesis, copy number, and ATP production in cultured myotubes, and found all three aspects to be decreased by uremic serum. Inhibition of autophagy partially reversed this decline in cultured myotubes. In CKD mice, the mitochondrial copy number, biogenesis marker peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), mitochondrial transcription factor A (TFAM), and mitochondrial fusion marker Mitofusin-2 (Mfn2) are decreased. Both muscle overloading and Acu/LFES increased mitochondrial copy number, and reversed the CKD-induced decreases in PGC-1α, TFAM, and Mfn2. We conclude that the autophagy is activated in the muscle of CKD mice. However, myofibrillar protein i...
Source: AJP: Renal Physiology - Category: Urology & Nephrology Authors: Tags: RESEARCH ARTICLE Source Type: research