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Oxidative Medicine and Cellular Longevity
Volume 2015 (2015), Article ID 684965, 18 pages
http://dx.doi.org/10.1155/2015/684965
Research Article

Myostatin Activates the Ubiquitin-Proteasome and Autophagy-Lysosome Systems Contributing to Muscle Wasting in Chronic Kidney Disease

1Department of Nephrology, Ruikang Hospital, Guangxi University of Chinese Medicine, Nanning 530011, China
2Department of Pharmacology, Guangdong Key Laboratory for R&D of Natural Drug, Guangdong Medical College, Zhanjiang 524023, China
3Department of Traditional Chinese Medicine, General Hospital of Guangzhou Military Command of PLA, Guangzhou 510010, China
4Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou 510280, China

Received 22 August 2014; Revised 18 October 2014; Accepted 11 December 2014

Academic Editor: Aldrin V. Gomes

Copyright © 2015 Dong-Tao Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Our evidence demonstrated that CKD upregulated the expression of myostatin, TNF-α, and p-IkBa and downregulated the phosphorylation of PI3K, Akt, and FoxO3a, which were also associated with protein degradation and muscle atrophy. The autophagosome formation and protein expression of autophagy-related genes were increased in muscle of CKD rats. The mRNA level and protein expression of MAFbx and MuRF-1 were also upregulated in CKD rats, as well as proteasome activity of 26S. Moreover, activation of myostatin elicited by TNF-α induces C2C12 myotube atrophy via upregulating the expression of autophagy-related genes, including MAFbx and MuRF1 and proteasome subunits. Inactivation of FoxO3a triggered by PI3K inhibitor LY294002 prevented the myostatin-induced increase of expression of MuRF1, MAFbx, and LC3-II protein in C2C12 myotubes. The findings were further consolidated by using siRNA interference and overexpression of myostatin. Additionally, expression of myostatin was activated by TNF-α via a NF-κB dependent pathway in C2C12 myotubes, while inhibition of NF-κB activity suppressed myostatin and improved myotube atrophy. Collectively, myostatin mediated CKD-induced muscle catabolism via coordinate activation of the autophagy and the ubiquitin-proteasome systems.