title: Fibroblast fiber contraction: role of C and Rho kinase in activation by thromboxane A2.
abstract: We investigated the mechanisms underlying regulation of contraction with measurements of isometric force and intracellular Ca2+ concentration ([Ca2+]i) in NIH 3T3 fibroblast reconstituted into fibers with the use of a collagen matrix. Treatment with the major phospholipids, neurotransmitters, and growth factors had little effect on baseline isometric force. However, U-46619, a thromboxane A2 (TxA2) analog, increased force and [Ca2+]i; EC50 values were 11.0 and 10.0 nM, respectively. The time courses were similar to those induced by calf serum (CS), and the maximal force was 65% of a CS-mediated contraction. The selective TxA2 receptor antagonist SQ-29548 abolished the U-46619-induced responses. CS-induced contractions are dependent on an intracellular Ca2+ store function; however, the U-46619 response depended not only on intracellular Ca2+ stores, but also on Ca2+ influx from the extracellular medium. Inhibition of Rho kinase suppressed U-46619- and CS-induced responses; in contrast, inhibition of C kinase (PKC) reduced only the U-46619 response. Moreover, addition of U-46619 to a CS contracture enhanced force and [Ca2+]i responses. These results indicate that U-46619-induced responses involve PKC and Rho kinase pathways, in contrast to activation by CS. Thus TxA2 may have a role in not only the initial step of wound repair as an activator of blood coagulation, but also in fibroblast contractility in later stages.
authors.affiliation: Dept. of Molecular and Cellular Physiology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267-0576, USA.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nobe
authors.forename: Koji
authors.initials: K
authors.lastname: Nobe
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Paul
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D016475:3T3 Cells; D000818:Animals; D002118:Calcium / Q000032:analysis / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology*; D007424:Intracellular Fluid / Q000737:chemistry; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013928:Thromboxane A2 / Q000494:pharmacology*; D014662:Vasoconstrictor Agents; D014945:Wound Healing / Q000502:physiology*; D054460:rho-Associated Kinases
chemical_list: D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D014662:Vasoconstrictor Agents; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D003094:Collagen; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D011493:Protein Kinase C; D002118:Calcium