Protein Kinase A, Ca2+/Calmodulin-Dependent Kinase II, and Calcineurin Regulate the Intracellular Trafficking of Myopodin between the Z-Disc and the Nucleus of …

C Faul, A Dhume, AD Schecter… - Molecular and cellular …, 2007 - Taylor & Francis
C Faul, A Dhume, AD Schecter, P Mundel
Molecular and cellular biology, 2007Taylor & Francis
Spatial and temporal resolution of intracellular signaling can be achieved by
compartmentalizing transduction units. Myopodin is a dual-compartment, actin-bundling
protein that shuttles between the nucleus and the Z-disc of myocytes in a differentiation-and
stress-dependent fashion. Importin α binding and nuclear import of myopodin are regulated
by serine/threonine phosphorylation-dependent binding of myopodin to 14-3-3. Here we
show that in the heart myopodin forms a Z-disc signaling complex with α-actinin, calcineurin …
Spatial and temporal resolution of intracellular signaling can be achieved by compartmentalizing transduction units. Myopodin is a dual-compartment, actin-bundling protein that shuttles between the nucleus and the Z-disc of myocytes in a differentiation- and stress-dependent fashion. Importin α binding and nuclear import of myopodin are regulated by serine/threonine phosphorylation-dependent binding of myopodin to 14-3-3. Here we show that in the heart myopodin forms a Z-disc signaling complex with α-actinin, calcineurin, Ca2+/calmodulin-dependent kinase II (CaMKII), muscle-specific A-kinase anchoring protein, and myomegalin. Phosphorylation of myopodin by protein kinase A (PKA) or CaMKII mediates 14-3-3 binding and nuclear import in myoblasts. Dephosphorylation of myopodin by calcineurin abrogates 14-3-3β binding. Activation of PKA or inhibition of calcineurin in adult cardiac myocytes releases myopodin from the Z-disc and induces its nuclear import. The identification of myopodin as a direct target of PKA, CaMKII, and calcineurin defines a novel intracellular signaling pathway whereby changes in Z-disc dynamics may translate into compartmentalized signal transduction in the heart.
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