Abstract
Previous work showed that calmodulin (CaM) and Ca$^2+$-CaM-dependent
protein kinase II (CaMKII) are somehow involved in cardiac hypertrophic
signaling, that inositol 1,4,5-trisphosphate receptors (InsP3Rs)
in ventricular myocytes are mainly in the nuclear envelope, where
they associate with CaMKII, and that class II histone deacetylases
(e.g., HDAC5) suppress hypertrophic gene transcription. Furthermore,
HDAC phosphorylation in response to neurohumoral stimuli that induce
hypertrophy, such as endothelin-1 (ET-1), activates HDAC nuclear
export, thereby regulating cardiac myocyte transcription. Here we
demonstrate a detailed mechanistic convergence of these 3 issues
in adult ventricular myocytes. We show that ET-1, which activates
plasmalemmal G protein-coupled receptors and InsP3 production, elicits
local nuclear envelope Ca$^2+$ release via InsP3R. This local
Ca$^2+$ release activates nuclear CaMKII, which triggers HDAC5
phosphorylation and nuclear export (derepressing transcription).
Remarkably, this Ca$^2+$-dependent pathway cannot be activated
by the global Ca$^2+$ transients that cause contraction at each
heartbeat. This novel local Ca$^2+$ signaling in excitation-transcription
coupling is analogous to but separate (and insulated) from that involved
in excitation-contraction coupling. Thus, myocytes can distinguish
simultaneous local and global Ca$^2+$ signals involved in contractile
activation from those targeting gene expression.
- 1,4,5-trisphosphate,
- 16511602
- active
- and
- animals,
- calcium
- calmodulin,
- cardiac,
- cell
- cells,
- channels,
- cultured,
- cytoplasmic
- deacetylases,
- dependent
- endothelin-1,
- envelope,
- extramural,
- genetic,
- gov't,
- histone
- inositol
- kinase,
- knockout,
- mice,
- myocytes,
- n.i.h.,
- non-u.s.
- nuclear
- nuclear,
- nucleus,
- protein
- rabbits,
- receptors,
- research
- signaling,
- support,
- transcription,
- transport,
- {c}a$^{2+}$-calmodulin
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