INVESTIGADORES
MATTIAZZI Ramona Alicia
artículos
Título:
The multifunctional Ca(2+)/calmodulin-dependent protein kinase II delta (CaMKIIδ) phosphorylates cardiac titin's spring elements.
Autor/es:
HIDALGO CG; CHUNG CS; SARIPALLI C; METHAWASIN M; HUTCHINSON KR; TSAPRAILIS G; LABEIT S; MATTIAZZI A; GRANZIER HL
Revista:
JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY
Editorial:
ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD
Referencias:
Lugar: Amsterdam; Año: 2013 p. 90 - 97
ISSN:
0022-2828
Resumen:
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 CaMKIIδ, 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 CaMKIIδ. It was found that CaMKIIδ phosphorylates titin in mouse LV
skinned fibers, that the CaMKIIδ 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
CaMKIIδ sites are phosphorylated. Mass spectrometry revealed that both
the N2B and PEVK segments are targeted by CaMKIIδ at several conserved
serine residues. Whether phosphorylation of titin by CaMKIIδ occurs in
vivo, was tested in several conditions using back phosphorylation assays
and phospho-specific antibodies to CaMKIIδ sites. Reperfusion following
global ischemia increased the phosphorylation level of CaMKIIδ 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 CaMKIIδ, both in vitro and in vivo, and
that titin's molecular spring region that determines diastolic stiffness
is a target of CaMKIIδ.