Deletion of MLCK210 induces subtle changes in vascular reactivity but does not affect cardiac function

Abstract

plays a key role in the regulation of actomyosin contraction in a large variety of cells. Two isoforms have been described: a short isoform, widely expressed in smooth muscle cells; and a long isoform (MLCK210), mainly localized in the endothelium. This study investigated the consequences on different cardiovascular parameters of MLCK210 gene deletion using MLCK210 knockout mice and of pharmacological inhibition of the kinase using a specific MLCK inhibitor. Deletion of MLCK210 did not affect systolic blood pressure and heart rate or echocardiographic measurements. Electrocardiographic analysis showed neither atrionor intraventricular conduction or repolarization defects. Ex vivo responses of aortic rings to vasoconstrictor and vasodilator agonists were not modified in MLCK210 null mice. However, deletion of MLCK210 attenuated shear stress-induced dilation and produced changes in the balance of endothelial-relaxing factors of small mesenteric arteries (SMA). In particular, a reduced flow-mediated NOdependent dilation was observed. However, it was partially compensated by enhanced indomethacin-sensitive dilation. No significant changes were detected in the endothelium-derived hyperpolarizing component of the vasodilator response. The above effects of MLCK210 gene deletion were confirmed in SMA from wild-type mice by the use of the MLCK enzymatic inhibitor MMZ-10 -057. In summary, deletion of MLCK210 was not associated with abnormalities of main in vivo cardiovascular parameters in mice. This study demonstrates a role for MLCK210 in the regulation of flow-dependent dilation in SMA. myosin light chain kinase 210; knockout mice; echocardiography; endothelium; vascular reactivity; shear stress MYOSIN LIGHT CHAIN KINASES (MLCK) are Ca 2ϩ

Cardiac Myosin Light Chain Kinase

“…These findings suggested that skeletal muscle MLCK does not play a major role in regulating cardiac MLC2. Similarly, ablation of the long form of smooth muscle MLCK, as described in another recent study, 12 did not affect cardiac function, as determined by systolic blood pressure, heart rate, or echocardiographic measurements. Electrocardiographic analysis showed neither atrio-nor intraventricular conduction or repolarization defects.…”

“…The study, indeed, has identified a new MLCK that is specifically expressed in the heart, although the presence of such a MLCK species is not unreasonable after we have learned from recent knockout studies as described above. 11,12 Kasahara and colleagues identified a rodent MLCK during the process of identifying genes regulated by cardiac homeobox protein Nkx2-5. The identified MLCK, which has been named "cardiac MLCK," as it would be expected, encodes 795 aa with a predicted molecular mass of 86 kDa excluding posttranslational modifications.…”

Rosiglitazone, a Peroxisome Proliferator-Activated Receptor-γ Agonist, Prevents Microparticle-Induced Vascular Hyporeactivity through the Regulation of Proinflammatory Proteins

“…; Pfizer Santé Animale, Paris, France) and killed by decapitation. Aortae were removed, and the adhering fat and connective tissue were carefully cleaned as described previously (Ralay Ranaivo et al, 2004;Ohlmann et al, 2005). Aortic rings of approximately 2 mm, after incubation in a medium with or without MPs, were mounted on a wire myograph filled with physiological salt solution of the following composition: 119 mM NaCl, 4.7 mM KCl, 14.9 mM NaHCO 3 , 1.2 mM MgSO 4 ⅐ 7H 2 O, 2.5 mM CaCl 2 , 1.18 mM KH 2 PO 4 , and 5.5 mM glucose at 37°C and gassed with 95% O 2 and 5% CO 2 .…”

Peculiarities of living cell response to the external stimuli revealed via quasistatic mode of atomic force microscopy

“…The contribution of different macromolecules and signaling events to EC mechanical phenotype is still poorly understood. Previous studies suggested the active role of actin cytoskeleton and regulatory proteins such as myosin light chain kinase in control of cellular stiffness and mechanosensing [22,23]. According to the accomplished measurements, height distribution across EC is heterogeneous: cell center has the maximum thickness (~ 1 μm) due to the presence of nucleus, while the distal regions are significantly thinner (~ 100 nm) (Fig.…”