Differential Control of Calcium Homeostasis and Vascular Reactivity by Ca ²⁺ /Calmodulin-Dependent Kinase II

Abstract

The multifunctional calcium/calmodulin-dependent kinase II (CaMKII) is activated by vasoconstrictors in vascular smooth muscle cells (VSMC), but its impact on vasoconstriction remains unknown. We hypothesized that CaMKII inhibition in VSMC decreases vasoconstriction. Using novel transgenic mice that express the inhibitor peptide CaMKIIN in smooth muscle (TG SM-CaMKIIN), we investigated the effect of CaMKII inhibition on L-type Ca2+ channel (LTCC) current (ICa), cytoplasmic and sarcoplasmic reticulum (SR) Ca2+ and vasoconstriction in mesenteric arteries. In mesenteric VSMC, CaMKII inhibition significantly reduced action potential duration and the residual ICa 50 ms after peak amplitude, indicative of loss of LTCC-dependent ICa facilitation. Treatment with angiotensin-II or phenylephrine increased the intracellular Ca2+ concentration ([Ca2+]i) in WT but not TG SM-CaMKIIN VSMC. The difference in [Ca2+]i was abolished by pretreatment with nifedipine, an LTCC antagonist. In TG SM-CaMKIIN VSMC, the total SR Ca2+ content was reduced as a result of diminished SR Ca2+ ATPase (SERCA) activity via impaired derepression of the SERCA inhibitor phospholamban. Despite the differences in [Ca2+]i, CaMKII inhibition did not alter myogenic tone or vasoconstriction of mesenteric arteries in response to KCl, angiotensin-II and phenylephrine. However, it increased myosin light chain kinase activity. These data suggest that CaMKII activity maintains intracellular calcium homeostasis but is not required for vasoconstriction of mesenteric arteries.

Integrin-linked kinase mediates force transduction in cardiomyocytes by modulating SERCA2a/PLN function

“…3c), corresponding to an increase in SERCA-2a function. CaMKII activation increases SERCA-2a function leading to increased SR Ca 2 þ content 42 . Accordingly, the effects of ILK overexpression on SR Ca 2 þ content were determined using caffeine to effect SR Ca 2 þ release through ryanodine receptor Ca 2 þ channels 43 ( Supplementary Fig.…”

Role of CaMKII in Ang-II-dependent small artery remodeling

“…All procedures were in compliance with the standards for the care and use of laboratory animals of the Institute of Laboratory Animal Resource, National Academy of Science. TG HA-CaMKIIN mice were generated as previously described [22] and backcrossed with C57Bl/6 mice and mated with mice carrying a Cre recombinase gene controlled by the SM22α promoter to generate TG SM-CaMKIIN mice (Jackson Laboratory, 004746) [27]. Littermates that did not carry the HA-CaMKIIN transgene served as wild-type (WT) controls.…”

“…We recently developed an in vivo model of transgenic CaMKII inhibition selectively in VSMC using the potent CaMKII inhibitor peptide, CaMKIIN. In this model, under baseline conditions, CaMKII inhibition in VSMC decreases intracellular and sarcoplasmic reticulum Ca 2+ levels without significantly affecting vasoconstriction or vascular structure [22]. However, after chronic Ang-II infusion, CaMKII inhibition reduces blood pressure, prevents of aortic stiffening and blunts splanchnic and renal nerve activity [23].…”

Control of cell mechanics by RhoA and calcium fluxes during epithelial scattering

“…86,87 Consistent with these findings, a CaMKII inhibitor peptide (CaMKIIN) increases MLCK activity. 88 Thus, CaMKII activation could have a role in the spreading phase of EMT, when myosin phosphorylation is decreased, though this idea is untested.…”