| First Author | Mohamed TM | Year | 2011 |
| Journal | J Biol Chem | Volume | 286 |
| Issue | 48 | Pages | 41520-9 |
| PubMed ID | 21965681 | Mgi Jnum | J:244286 |
| Mgi Id | MGI:5913065 | Doi | 10.1074/jbc.M111.290411 |
| Citation | Mohamed TM, et al. (2011) Plasma membrane calcium pump (PMCA4)-neuronal nitric-oxide synthase complex regulates cardiac contractility through modulation of a compartmentalized cyclic nucleotide microdomain. J Biol Chem 286(48):41520-9 |
| abstractText | Identification of the signaling pathways that regulate cyclic nucleotide microdomains is essential to our understanding of cardiac physiology and pathophysiology. Although there is growing evidence that the plasma membrane Ca(2+)/calmodulin-dependent ATPase 4 (PMCA4) is a regulator of neuronal nitric-oxide synthase, the physiological consequence of this regulation is unclear. We therefore tested the hypothesis that PMCA4 has a key structural role in tethering neuronal nitric-oxide synthase to a highly compartmentalized domain in the cardiac cell membrane. This structural role has functional consequences on cAMP and cGMP signaling in a PMCA4-governed microdomain, which ultimately regulates cardiac contractility. In vivo contractility and calcium amplitude were increased in PMCA4 knock-out animals (PMCA4(-/-)) with no change in diastolic relaxation or the rate of calcium decay, showing that PMCA4 has a function distinct from beat-to-beat calcium transport. Surprisingly, in PMCA4(-/-), over 36% of membrane-associated neuronal nitric-oxide synthase (nNOS) protein and activity was delocalized to the cytosol with no change in total nNOS protein, resulting in a significant decrease in microdomain cGMP, which in turn led to a significant elevation in local cAMP levels through a decrease in PDE2 activity (measured by FRET-based sensors). This resulted in increased L-type calcium channel activity and ryanodine receptor phosphorylation and hence increased contractility. In the heart, in addition to subsarcolemmal calcium transport, PMCA4 acts as a structural molecule that maintains the spatial and functional integrity of the nNOS signaling complex in a defined microdomain. This has profound consequences for the regulation of local cyclic nucleotide and hence cardiac beta-adrenergic signaling. |
