scholarly journals Myosin Phosphatase and Cofilin Mediate cAMP/cAMP-dependent Protein Kinase-induced Decline in Endothelial Cell Isometric Tension and Myosin II Regulatory Light Chain Phosphorylation

2005 ◽  
Vol 280 (38) ◽  
pp. 33083-33095 ◽  
Author(s):  
Zoe M. Goeckeler ◽  
Robert B. Wysolmerski
Keyword(s):  
Endothelial Cell ◽  
Protein Kinase ◽  
Light Chain ◽  
Myosin Ii ◽  
Regulatory Light Chain ◽  
Isometric Tension ◽  
Myosin Phosphatase ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Regulatory Light Chain Phosphorylation

scholarly journals Characterization of Ca2+/calmodulin-dependent protein kinase I as a myosin II regulatory light chain kinase in vitro and in vivo

2002 ◽  
Vol 367 (2) ◽  
pp. 335-345 ◽  
Author(s):  
Futoshi SUIZU ◽  
Yasuaki FUKUTA ◽  
Kozue UEDA ◽  
Takahiro IWASAKI ◽  
Hiroshi TOKUMITSU ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Light Chain ◽  
Actin Filaments ◽  
Myosin Ii ◽  
Regulatory Light Chain ◽  
Dominant Negative Effect ◽  
Dependent Manner ◽  
Dependent Protein Kinase ◽  
Dependent Protein

Ca2+/calmodulin (CaM)-dependent protein kinase I (CaM-KI), which is a member of the multifunctional CaM-K family, is thought to be involved in various Ca2+-signalling pathways. In this report, we demonstrate that CaM-KI activated by an upstream kinase (CaM-K kinase), but not unactivated CaM-KI, phosphorylates myosin II regulatory light chain (MRLC) efficiently (Kcat, 1.7s-1) and stoichiometrically (0.8mol of phosphate/mol) in a Ca2+/CaM-dependent manner in vitro. One-dimensional phosphopeptide mapping and mutational analysis of MRLC revealed that the activated CaM-KI monophosphorylates only Ser-19 in MRLC. Transient expression of the Ca2+/CaM-independent form of CaM-KI (CaM-KI1-293) in HeLa cells induced Ser-19 phosphorylation of myosin, II accompanied by reorganization of actin filaments in the peripheral region of the cells. CaM-KI-induced reorganization of actin filaments was suppressed by co-expression of non-phosphorylatable MRLC mutants (S19A and T18AS19A). Furthermore, a kinase-negative form of CaM-KI (CaM-KI1-293,K49E) significantly reduced reorganization of actin filaments, indicating a dominant negative effect. This is the first demonstration that the activation of the CaM-KI cascade induces myosin II phosphorylation, resulting in regulation of actin filament organization in mammalian cells.

Physiological concentration of atrial natriuretic peptide induces endothelial regeneration in vitro

2003 ◽  
Vol 284 (4) ◽  
pp. H1388-H1397 ◽  
Author(s):  
Hyun Kook ◽  
Hiroshi Itoh ◽  
Bong Seok Choi ◽  
Naoki Sawada ◽  
Kentaro Doi ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Protein Kinase ◽  
Dependent Protein Kinase ◽  
Physiological Concentration ◽  
Cell Numbers ◽  
Cgmp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Regeneration In Vitro

Both nitric oxide (NO) and natriuretic peptides produce apoptosis of vascular smooth muscle cells. However, there is evidence that NO induces endothelial cell proliferation, which suggests that there is a difference in the response of endothelial cells to natriuretic peptides. The purpose of this study was to investigate the effect of atrial natriuretic peptide (ANP) on human endothelial cell survival. ANP within the physiological concentration (10−11mol/l) induced a 52% increase in the number of human coronary arterial endothelial cells and a 63% increase in human umbilical vein endothelial cells at a low concentration of serum. The increase in cell numbers was blocked by pretreatment with RP8-CPT-cGMP (RP8), a cGMP-dependent protein kinase inhibitor, with wortmannin, an Akt/PKB inhibitor, and with PD-98059, an ERK1/2 inhibitor. In a Transwell migration test, ANP also increased the cell migration, and RP8, wortmannin, and PD-98059 blocked this increase. A wound healing assay was performed to examine the effects of ANP on regeneration in vitro. ANP increased both cell numbers and migration, but the effects were blocked by the above three kinase inhibitors. ANP increased the expression of phospho-Akt and of phospho-ERK1/2 within 1.5 h. These results suggest that ANP can potentiate endothelial regeneration by cGMP-dependent protein kinase stimulation and subsequent Akt and ERK1/2 activations.

scholarly journals Nonmuscle myosin II is responsible for maintaining endothelial cell basal tone and stress fiber integrity

2008 ◽  
Vol 295 (4) ◽  
pp. C994-C1006 ◽  
Author(s):  
Zoe M. Goeckeler ◽  
Paul C. Bridgman ◽  
Robert B. Wysolmerski
Keyword(s):  
Endothelial Cell ◽  
Light Chain ◽  
Actin Polymerization ◽  
Myosin Ii ◽  
Rho Kinase ◽  
Specific Inhibitor ◽  
Isometric Tension ◽  
Stress Fiber ◽  
Tension Development ◽  
Basal Tone

Cultured confluent endothelial cells exhibit stable basal isometric tone associated with constitutive myosin II regulatory light chain (RLC) phosphorylation. Thrombin treatment causes a rapid increase in isometric tension concomitant with myosin II RLC phosphorylation, actin polymerization, and stress fiber reorganization while inhibitors of myosin light chain kinase (MLCK) and Rho-kinase prevent these responses. These findings suggest a central role for myosin II in the regulation of endothelial cell tension. The present studies examine the effects of blebbistatin, a specific inhibitor of myosin II activity, on basal tone and thrombin-induced tension development. Although blebbistatin treatment abolished basal tension, this was accompanied by an increase in myosin II RLC phosphorylation. The increase in RLC phosphorylation was Ca2+ dependent and mediated by MLCK. Similarly, blebbistatin inhibited thrombin-induced tension without interfering with the increase in RLC phosphorylation or in F-actin polymerization. Blebbistatin did prevent myosin II filament incorporation and association with polymerizing or reorganized actin filaments leading to the disappearance of stress fibers. Thus the inhibitory effects of blebbistatin on basal tone and induced tension are consistent with a requirement for myosin II activity to maintain stress fiber integrity.

scholarly journals Myosin light chain kinase-regulated endothelial cell contraction: the relationship between isometric tension, actin polymerization, and myosin phosphorylation.

1995 ◽  
Vol 130 (3) ◽  
pp. 613-627 ◽  
Author(s):  
Z M Goeckeler ◽  
R B Wysolmerski
Keyword(s):  
Endothelial Cell ◽  
Light Chain ◽  
Isometric Contraction ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Myosin Ii ◽  
Isometric Tension ◽  
Stress Fibers ◽  
Light Chains ◽  
Myosin Light Chains

The phosphorylation of regulatory myosin light chains by the Ca2+/calmodulin-dependent enzyme myosin light chain kinase (MLCK) has been shown to be essential and sufficient for initiation of endothelial cell retraction in saponin permeabilized monolayers (Wysolmerski, R. B. and D. Lagunoff. 1990. Proc. Natl. Acad. Sci. USA. 87:16-20). We now report the effects of thrombin stimulation on human umbilical vein endothelial cell (HUVE) actin, myosin II and the functional correlate of the activated actomyosin based contractile system, isometric tension development. Using a newly designed isometric tension apparatus, we recorded quantitative changes in isometric tension from paired monolayers. Thrombin stimulation results in a rapid sustained isometric contraction that increases 2- to 2.5-fold within 5 min and remains elevated for at least 60 min. The phosphorylatable myosin light chains from HUVE were found to exist as two isoforms, differing in their molecular weights and isoelectric points. Resting isometric tension is associated with a basal phosphorylation of 0.54 mol PO4/mol myosin light chain. After thrombin treatment, phosphorylation rapidly increases to 1.61 mol PO4/mol myosin light chain within 60 s and remains elevated for the duration of the experiment. Myosin light chain phosphorylation precedes the development of isometric tension and maximal phosphorylation is maintained during the sustained phase of isometric contraction. Tryptic phosphopeptide maps from both control and thrombin-stimulated cultures resolve both monophosphorylated Ser-19 and diphosphorylated Ser-19/Thr-18 peptides indicative of MLCK activation. Changes in the polymerization of actin and association of myosin II correlate temporally with the phosphorylation of myosin II and development of isometric tension. Activation results in a 57% increase in F-actin content within 90 s and 90% of the soluble myosin II associates with the reorganizing F-actin. Furthermore, the disposition of actin and myosin II undergoes striking reorganization. F-actin initially forms a fine network of filaments that fills the cytoplasm and then reorganizes into prominent stress fibers. Myosin II rapidly forms discrete aggregates associated with the actin network and by 2.5 min assumes a distinct periodic distribution along the stress fibers.

Calmodulin-dependent myosin light chain kinases from cardiac and smooth muscle: a comparative study

1980 ◽  
Vol 58 (4) ◽  
pp. 299-308 ◽  
Author(s):  
Michael P. Walsh ◽  
Jean-Claude Cavadore ◽  
Bernard Vallet ◽  
Jacques G. Demaille
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Phosphorylation Site ◽  
Dependent Protein Kinase ◽  
Proteolytic Fragment ◽  
Cardiac Enzyme ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

Various properties of cardiac and smooth muscle calmodulin-dependent myosin light chain kinases (MLCKs) have been compared. The enzymes exhibit the same isoelectric point (6.5) but differ markedly in molecular weight (Mr = 72 000 for both canine and bovine cardiac MLCK, and Mr = 130 000 for smooth muscle MLCK). Comparison of the tryptic peptide maps of bovine cardiac and turkey gizzard MLCKs indicates that the cardiac enzyme is a fragment of a protein homologous to the smooth muscle kinase. While the smooth muscle kinase can be phosphorylated by the catalytic subunit of cAMP-dependent protein kinase, the same is not true for either bovine or canine cardiac MLCK. Controlled tryptic hydrolysis of phosphorylated smooth muscle MLCK, followed by affinity chromatography on a column of calmodulin–Sepharose, enables separation of a phosphopeptide (Mr = 22 000) from a mixture of peptides of Mr = 50 000 and 24 000 which are bound to the column in the presence of Ca2+ and eluted with ethylene glycol bis(β-aminoethyl ether)-N,N′-tetraacetic acid. The phosphorylation site, therefore, is distinct from the calmodulin-binding site. It appears that cardiac MLCK is proteolyzed during the isolation procedure. The purified cardiac enzyme represents a proteolytic fragment which retains Ca2+ and calmodulin dependence but only a fraction of the specific activity of the native enzyme, and has lost the site of phosphorylation by cAMP-dependent protein kinase. A protease is shown to exist in myocardium which is capable of digesting smooth muscle MLCK rapidly at low temperature, and which is resistant to classical antiproteases.

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