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Abstract

Phosphorylation of cardiac troponin is a key mechanism involved in regulation of contractile function. In vitro kinase assays revealed that lysates prepared from resting cardiomyocytes contain cardiac troponin I (cTnI) and cTnT kinase activity. cTnI phosphorylation is inhibited by pharmacologic inhibitors of PKA, PKC, Rho kinase and PKC effectors such as RSK and PKD; these kinase inhibitors do not inhibit phosphorylation of cTnT. Rather, cTnT phosphorylation is decreased by the Raf inhibitor GW5074. In vitro kinase assays show that recombinant Raf phosphorylates cTnT, and that Raf-dependent cTnT phosphorylation is abrogated by a T206E substitution; Raf does not phosphorylate cTnI. These studies identify Raf-dependent cTnT-Thr206 phosphorylation as a novel mechanism that would link growth factor-dependent signaling pathways to dynamic changes in cardiac contractile function.

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Abbreviations

PKA:

Protein kinase A

PKC:

Protein kinase C

PKD:

Protein kinase D

PDK:

Phosphoinositide-dependent protein kinase

ASK-1:

Apoptosis signal-regulating kinase-1

RSK:

Ribosomal S6 kinase

ROCK:

Rho-A-dependent kinase

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Acknowledgments

This work was supported by United States Public Health Service—National Heart, Lung and Blood Institute grants HL-77860, HL-74161, and AHA-SDG 0335199 N.

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Correspondence to Marius P. Sumandea.

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Pfleiderer, P., Sumandea, M.P., Rybin, V.O. et al. Raf-1: a novel cardiac troponin T kinase. J Muscle Res Cell Motil 30, 67–72 (2009). https://doi.org/10.1007/s10974-009-9176-y

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  • DOI: https://doi.org/10.1007/s10974-009-9176-y

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