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Medicine Matters Home Article of the Week Citrullination of myofilament proteins in heart failure

Citrullination of myofilament proteins in heart failure

ARTICLE: Citrullination of myofilament proteins in heart failure

AUTHORS: J. Fert-Bober, J.T. Giles, R.J. Holewinski, J.A. Kirk, H. Uhrigshardt, E.L. Crowgey, F. Andrade, C.O. Bingham 3rd, J.K. Park, M.K. Halushka, D.A. Kass, J.M. Bathon and J.E. Van Eyk

JOURNAL: Cardiovasc Res. 2015 Jun 25. pii: cvv185. [Epub ahead of print]


AIM: Citrullination, the post-translational conversion of arginine to citrulline by the enzyme family of peptidylarginine deiminase (PADs), is associated with several diseases and specific citrullinated proteins have been shown to alter function while others act as auto-antigens. In this study, we identified citrullinated proteins in human myocardial samples, from healthy and heart failure patients, and determined several potential functional consequences. Further we investigated PAD isoform cell-specific expression in the heart

METHODS AND RESULTS: A citrullination-targeted proteomic strategy using data independent (SWATH) acquisition method was used to identify the modified cardiac proteins. Citrullinated-induced sarcomeric proteins were validated by 2-dimensional gel electrophoresis and investigated using biochemical and functional assays. Myocardial PAD isoforms were confirmed by RT-PCR with PAD2 being the major isoform in myocytes. In total, 304 citrullinated sites were identified that map to 145 proteins among the three study groups; normal, ischemia and dilated cardiomyopathy. Citrullination of myosin (using HMM fragment) decreased its intrinsic ATPase activity and inhibited the acto-HMM ATPase activity. Citrullinated TM resulted in stronger F-actin binding and inhibited the acto-HMM ATPase activity. Citrullinated TnI did not alter the binding to F-actin or acto-HMM ATPase activity. Overall, citrullination of sarcomeric proteins caused a decrease in Ca2+-sensitivity in skinned cardiomyocytes, with no change in maximal calcium activated force or hill coefficient.

CONCLUSIONS: Citrullination unique to the cardiac proteome was identified. Our data indicate important structural and functional alterations to the cardiac sarcomere and the contribution of protein citrullination to this process.

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Kelsey Bennett