Chronic exposure to TXA2 increases expression of ROCKI in human myometrial cells.
Increased expression of RhoA-associated protein kinase (ROK) in human pregnant myometrial tissue is due to increased expression of the p160ROKI isoform. Expression and proteolysis of p160ROKI was investigated in cultured primary human uterine smooth muscle cells stimulated with the stable thromboxane A2 (TXA2) analogue U46619. Acute exposure to U46619 showed no change in protein expression or cleavage of p160ROKI. Chronic exposure to U46619 resulted in a concentration-dependent increase in protein expression of p160ROKI that was inhibited by pre-treatment of the cells with the C3-exotoxin. Pre-incubation with the thromboxane receptor antagonist SQ29548 also blocked the U46619-mediated increase in p160ROKI protein expression but at the same time promoted increased proteolysis of pre-existing p160ROKI to p130ROKI. Pre-treatment of the cells with the caspase 3 inhibitor Z-DEVD-FMK blocked the cleavage of p160ROKI. These findings show that ROKI is an inducible isoform whose aberrant expression and cleavage needs to be controlled to prevent contractile dysfunction.
Nuffield Department of Obstetrics and Gynaecology, John Radcliffe Hospital, University of Oxford, Headington, Oxford OX3 9DU, UK. frances.moore@obs-gyn.ox.ac.uk
Frances
F
Moore
Andrés
A
López Bernal
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes / Q000096:biosynthesis; D009215:Myometrium / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology*; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000378:metabolism*; D054460:rho-Associated Kinases
D061945:Caspase Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; D017482:Receptors, Thromboxane; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D020169:Caspases; D002118:Calcium