STAT-3-dependent cytosolic phospholipase A2 expression is required for thrombin-induced vascular smooth muscle cell motility.
Vascular smooth muscle cell (VSMC) migration from media to intima and its multiplication in intima is a contributing factor in the pathogenesis of atherosclerosis and restenosis after angioplasty. Previously, we have demonstrated that STAT-3-dependent cytosolic phospholipase A(2) (cPLA(2)) expression is needed for VSMC motility induced by platelet-derived growth factor-BB, a receptor tyrosine kinase agonist (Neeli et al. (2005) J. Biol. Chem. 279, 46122-46128). In order to learn more about the STAT-3-cPLA(2) axis in motogenic signaling, here we have studied its role in VSMC motility in response to a G protein-coupled receptor (GPCR) agonist, thrombin. Thrombin induced VSMC motility in a dose-dependent manner with a maximum effect at 0.5 units/ml. Thrombin activated STAT-3 as measured by its tyrosine phosphorylation and translocation from the cytoplasm to the nucleus. Forced expression of a dominant negative mutant of STAT-3 reduced thrombin-induced STAT-3 tyrosine phosphorylation and its translocation from the cytoplasm to the nucleus. Thrombin stimulated STAT-3-DNA binding and reporter gene activities in VSMC, and these responses were blocked by FS3DM, a dominant negative mutant of STAT-3. FS3DM also attenuated thrombin-induced VSMC motility. Thrombin induced the expression of cPLA(2) in a time- and STAT-3-dependent manner. In addition, pharmacological inhibition of cPLA(2) blocked thrombin-induced VSMC motility. Furthermore, exogenous addition of arachidonic acid rescued thrombin-induced VSMC motility from inhibition by blockade of STAT-3 activation. Forced expression of cPLA(2) also surpassed the inhibitory effect of dominant negative STAT-3 on thrombin-induced VSMC motility. Together, these results show that thrombin-induced VSMC motility requires STAT-3-dependent induction of expression of cPLA(2).
Dronadula
Nagadhara
N
Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
Liu
Zhimin
Z
Wang
Chunmei
C
Cao
Huiqing
H
Rao
Gadiparthi N
GN
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002465:Cell Movement; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D005799:Genes, Dominant; D017930:Genes, Reporter; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D009154:Mutation; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D010766:Phosphorylation; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D013917:Thrombin / Q000378:metabolism*; D013997:Time Factors; D015534:Trans-Activators / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics*; D014443:Tyrosine / Q000378:metabolism
D004268:DNA-Binding Proteins; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D015534:Trans-Activators; D014443:Tyrosine; D004247:DNA; D010741:Phospholipases A; D054467:Phospholipases A2; D013917:Thrombin