当前位置： SCI文献检索 > JOURNAL OF MUSCLE RESEARCH AND CELL MOTILITY期刊下所有文献 > Protein kinase C depresses cardiac myocyte power output and attenuates myofilament responses induced by protein kinase A.

Protein kinase C depresses cardiac myocyte power output and attenuates myofilament responses induced by protein kinase A.

Abstract：

:Following activation by G-protein-coupled receptor agonists, protein kinase C (PKC) modulates cardiac myocyte function by phosphorylation of intracellular targets including myofilament proteins cardiac troponin I (cTnI) and cardiac myosin binding protein C (cMyBP-C). Since PKC phosphorylation has been shown to decrease myofibril ATPase activity, we hypothesized that PKC phosphorylation of cTnI and cMyBP-C will lower myocyte power output and, in addition, attenuate the elevation in power in response to protein kinase A (PKA)-mediated phosphorylation. We compared isometric force and power generating capacity of rat skinned cardiac myocytes before and after treatment with the catalytic subunit of PKC. PKC increased phosphorylation levels of cMyBP-C and cTnI and decreased both maximal Ca(2+) activated force and Ca(2+) sensitivity of force. Moreover, during submaximal Ca(2+) activations PKC decreased power output by 62 %, which arose from both the fall in force and slower loaded shortening velocities since depressed power persisted even when force levels were matched before and after PKC. In addition, PKC blunted the phosphorylation of cTnI by PKA, reduced PKA-induced spontaneous oscillatory contractions, and diminished PKA-mediated elevations in myocyte power. To test whether altered thin filament function plays an essential role in these contractile changes we investigated the effects of chronic cTnI pseudo-phosphorylation on myofilament function using myocyte preparations from transgenic animals in which either only PKA phosphorylation sites (Ser-23/Ser-24) (PP) or both PKA and PKC phosphorylation sites (Ser-23/Ser-24/Ser-43/Ser-45/T-144) (All-P) were replaced with aspartic acid. Cardiac myocytes from All-P transgenic mice exhibited reductions in maximal force, Ca(2+) sensitivity of force, and power. Similarly diminished power generating capacity was observed in hearts from All-P mice as determined by in situ pressure-volume measurements. These results imply that PKC-mediated phosphorylation of cTnI plays a dominant role in depressing contractility, and, thus, increased PKC isozyme activity may contribute to maladaptive behavior exhibited during the progression to heart failure.

journal_name

J Muscle Res Cell Motil

journal_title

Journal of muscle research and cell motility

authors

Hinken AC,Hanft LM,Scruggs SB,Sadayappan S,Robbins J,Solaro RJ,McDonald KS

doi

10.1007/s10974-012-9294-9

subject

Has Abstract

pub_date

2012-12-01 00:00:00

pages

439-48

issue

eissn

0142-4319

issn

1573-2657

journal_volume

pub_type

杂志文章

在线工具

Protein kinase C depresses cardiac myocyte power output and attenuates myofilament responses induced by protein kinase A.