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The multifunctional Ca(2+)/calmodulin-dependent protein kinase II delta (CaMKII?) phosphorylates cardiac titin's spring elements.

ABSTRACT: Titin-based passive stiffness is post-translationally regulated by several kinases that phosphorylate specific spring elements located within titin's elastic I-band region. Whether titin is phosphorylated by calcium/calmodulin dependent protein kinase II (CaMKII), an important regulator of cardiac function and disease, has not been addressed. The aim of this work was to determine whether CaMKII?, the predominant CaMKII isoform in the heart, phosphorylates titin, and to use phosphorylation assays and mass spectrometry to study which of titin's spring elements might be targeted by CaMKII?. It was found that CaMKII? phosphorylates titin in mouse LV skinned fibers, that the CaMKII? sites can be dephosphorylated by protein phosphatase 1 (PP1), and that under baseline conditions, in both intact isolated hearts and skinned myocardium, about half of the CaMKII? sites are phosphorylated. Mass spectrometry revealed that both the N2B and PEVK segments are targeted by CaMKII? at several conserved serine residues. Whether phosphorylation of titin by CaMKII? occurs in vivo, was tested in several conditions using back phosphorylation assays and phospho-specific antibodies to CaMKII? sites. Reperfusion following global ischemia increased the phosphorylation level of CaMKII? sites on titin and this effect was abolished by the CaMKII inhibitor KN-93. No changes in the phosphorylation level of the PEVK element were found suggesting that the increased phosphorylation level of titin in IR (ischemia reperfusion) might be due to phosphorylation of the N2B element. The findings of these studies show for the first time that titin can be phosphoryalated by CaMKII?, both in vitro and in vivo, and that titin's molecular spring region that determines diastolic stiffness is a target of CaMKII?.

SUBMITTER: Hidalgo CG

PROVIDER: S-EPMC3535572 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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The multifunctional Ca(2+)/calmodulin-dependent protein kinase II delta (CaMKIIδ) phosphorylates cardiac titin's spring elements.

Hidalgo Carlos G CG Chung Charles S CS Saripalli Chandra C Methawasin Mei M Hutchinson Kirk R KR Tsaprailis George G Labeit Siegfried S Mattiazzi Alicia A Granzier Henk L HL

Journal of molecular and cellular cardiology 20121205

Titin-based passive stiffness is post-translationally regulated by several kinases that phosphorylate specific spring elements located within titin's elastic I-band region. Whether titin is phosphorylated by calcium/calmodulin dependent protein kinase II (CaMKII), an important regulator of cardiac function and disease, has not been addressed. The aim of this work was to determine whether CaMKIIδ, the predominant CaMKII isoform in the heart, phosphorylates titin, and to use phosphorylation assays ...[more]

PMID: 23220127

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Dataset Information

The multifunctional Ca(2+)/calmodulin-dependent protein kinase II delta (CaMKII?) phosphorylates cardiac titin's spring elements.

Publications

The multifunctional Ca(2+)/calmodulin-dependent protein kinase II delta (CaMKIIδ) phosphorylates cardiac titin's spring elements.

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