HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 280, Issue 38, 33083-33095, September 23, 2005

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 280/38/33083    most recent M503173200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Goeckeler, Z. M. Articles by Wysolmerski, R. B. Search for Related Content PubMed PubMed Citation Articles by Goeckeler, Z. M. Articles by Wysolmerski, R. B. Social Bookmarking                      What's this?

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

From the Department of Pathology, St. Louis University School of Medicine, St. Louis, Missouri 63104

This study determined the effects of increased intracellular cAMP and cAMP-dependent protein kinase activation on endothelial cell basal and thrombin-induced isometric tension development. Elevation of cAMP and maximal cAMP-dependent protein kinase activation induced by 10 µM forskolin, 40 µM 3-isobutyl-1-methylxanthine caused a 50% reduction in myosin II regulatory light chain (RLC) phosphorylation and a 35% drop in isometric tension, but it did not inhibit thrombin-stimulated increases in RLC phosphorylation and isometric tension. Elevation of cAMP did not alter myosin light chain kinase catalytic activity. However, direct inhibition of myosin light chain kinase with KT5926 resulted in a 90% decrease in RLC phosphorylation and only a minimal decrease in isometric tension, but it prevented thrombin-induced increases in RLC phosphorylation and isometric tension development. We showed that elevated cAMP increases phosphorylation of RhoA 10-fold, and this is accompanied by a 60% decrease in RhoA activity and a 78% increase in RLC phosphatase activity. Evidence is presented that it is this inactivation of RhoA that regulates the decrease in isometric tension through a pathway involving cofilin. Activated cofilin correlates with increased F-actin severing activity in cell extracts from monolayers treated with forskolin/3-isobutyl-1-methylxanthine. Pretreatment of cultures with tautomycin, a protein phosphatase type 1 inhibitor, blocked the effect of cAMP on 1) the dephosphorylation of cofilin, 2) the decrease in RLC phosphorylation, and 3) the decrease in isometric tension. Together, these data provide in vivo evidence that elevated intracellular cAMP regulates endothelial cell isometric tension and RLC phosphorylation through inhibition of RhoA signaling and its downstream pathways that regulate myosin II activity and actin reorganization.

Received for publication, March 22, 2005 , and in revised form, July 5, 2005.

^* This work was supported by NHLBI Grant HL-45788 from the National Institutes of Health and American Heart Association Grant-in-aid 0160285Z (to Z. M. G.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains Figs. S1-S3.

¹ To whom correspondence should be addressed: Dept. of Pathology, St. Louis University School of Medicine, 1402 South Grand Blvd., St. Louis, MO 63104. Tel.: 314-577-8497; Fax: 314-268-5649; E-mail: wysolmrb{at}slu.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				C. D'hondt, S. P. Srinivas, J. Vereecke, and B. Himpens Adenosine Opposes Thrombin-Induced Inhibition of Intercellular Calcium Wave in Corneal Endothelial Cells Invest. Ophthalmol. Vis. Sci., April 1, 2007; 48(4): 1518 - 1527. [Abstract] [Full Text] [PDF]

				S. P. Srinivas, M. Satpathy, Y. Guo, and V. Anandan Histamine-Induced Phosphorylation of the Regulatory Light Chain of Myosin II Disrupts the Barrier Integrity of Corneal Endothelial Cells. Invest. Ophthalmol. Vis. Sci., September 1, 2006; 47(9): 4011 - 4018. [Abstract] [Full Text] [PDF]

				B. Zhu, K. Fukada, H. Zhu, and N. Kyprianou Prohibitin and Cofilin Are Intracellular Effectors of Transforming Growth Factor {beta} Signaling in Human Prostate Cancer Cells. Cancer Res., September 1, 2006; 66(17): 8640 - 8647. [Abstract] [Full Text] [PDF]

				L. T. Lubomirov, K. Reimann, D. Metzler, V. Hasse, R. Stehle, M. Ito, D. J. Hartshorne, H. Gagov, G. Pfitzer, and R. Schubert Urocortin-Induced Decrease in Ca2+ Sensitivity of Contraction in Mouse Tail Arteries Is Attributable to cAMP-Dependent Dephosphorylation of MYPT1 and Activation of Myosin Light Chain Phosphatase Circ. Res., May 12, 2006; 98(9): 1159 - 1167. [Abstract] [Full Text] [PDF]