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Author Notes:

Correspondence: Dr. Xiaonan Wang, Renal Division, Emory University, School of Medicine, M/S 1930/001/1AG, 1639 Pierce Drive, WMB 338, Atlanta, GA 30322. Phone: 404-727-1798. Fax: 404-727-3425. Email: xwang03@emory.edu.

Dr. Young Zhang kindly provided pBSCX1-LEL plasmid vector and technical support.

There are no conflicts of interest to disclose.

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Research Funding:

This work was supported in part by a Norman S. Coplon Extramural Research Grant from Satellite Health; the University Research Committee of Emory University; and National Institutes of Health grants DK62796 to X.H.W., DK062081 to J.D.K., DK50740 and DK61521 to S.R.P., and HL70762 to J.D.

XIAP Reduces Muscle Proteolysis Induced by CKD

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Journal Title:

Journal of the American Society of Nephrology

Volume:

Volume 21, Number 7

Publisher:

, Pages 1174-1183

Type of Work:

Article | Post-print: After Peer Review

Abstract:

X-chromosome-linked inhibitor of apoptosis protein (XIAP) is an endogenous caspase inhibitor. Caspase-3 contributes to the muscle wasting associated with chronic kidney disease (CKD) and other systemic illnesses, but whether XIAP modulates muscle wasting in CKD is unknown. Here, overexpression of XIAP in cultured skeletal muscle cells decreased protein degradation induced by serum deprivation, suggesting that caspase-mediated proteolysis contributes to muscle atrophy. We generated transgenic mice that overexpress human XIAP specifically in skeletal muscle (mXIAP) and evaluated muscle protein degradation induced by CKD. mXIAP mice with normal kidney function exhibited mild skeletal muscle hypertrophy. Muscle weights of mXIAP mice with CKD (mXIAP-CKD) were indistinguishable from wild-type mice, suggesting that overexpression of XIAP in skeletal muscle protects from CKD-induced muscle atrophy. The rate of total protein degradation, proteasome chymotrypsin–like activity, and caspase-3–mediated actin cleavage all were lower in muscle isolated from mXIAP-CKD mice compared with wild-type CKD mice. Concomitant with the reduction in overall proteolysis, mRNA levels of ubiquitin, muscle-specific ring finger 1, and atrogin-1/muscle atrophy F-box were lower in mXIAP-CKD mice, suggesting that decreased expression of the ubiquitin–proteasome pathway components may contribute to the protein-sparing effects of XIAP. In summary, these results demonstrate that XIAP inhibits multiple aspects of protein degradation in skeletal muscle during CKD.

Copyright information:

© 2010 by the American Society of Nephrology

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