Transactivation of EGFR/PI3K/Akt involved in ATP-induced inflammatory protein expression and cell motility

✍ Scribed by Chih-Chung Lin; Wei-Ning Lin; Shin-Ei Cheng; Wei-Hsuan Tung; Hui-Hsin Wang; Chuen-Mao Yang

• Publisher: John Wiley and Sons
• Year: 2012
• Tongue: English
• Weight: 982 KB
• Volume: 227
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.22880

✦ Synopsis

Phenotype transition of vascular smooth muscle cells (VSMCs) is important in vascular diseases, such as atherosclerosis and restenosis. Once released, ATP may promote activation of VSMCs by stimulating cyclooxygenase-2 (COX-2), cytosolic phospholipase A 2 (cPLA 2 ) expression and prostaglandin (PG)E 2 synthesis via activation of MAPKs and NF-kB. However, whether alternative signaling pathways participated in regulating COX-2 and cPLA 2 expression associated with cell migration were investigated in rat VSMCs. Western blot analysis, RT-PCR, promoter assay and PGE 2 ELISA were used to determine expression of COX-2, cPLA 2 and PGE 2 . Specific inhibitors and siRNAs against various protein kinases or transcription factors were used to investigate the related signaling components in inflammatory protein induction by ATPgS. We found that ATPgS-induced COX-2 and cPLA 2 expression and PGE 2 release was attenuated by the pharmacological inhibitors or transfection with siRNA against PKCd, c-Src, EGFR, PI3-K, Akt, p44/p42 MAPK or Elk-1. Moreover, ATPgSstimulated phosphorylation of PKCd, c-Src, EGFR, Akt, p42/p44 MAPK and Elk-1, suggesting the participation of PKCd/c-Src/EGFR/PI3-K/ Akt/p42/p44 MAPK cascade in mediating Elk-1 activities in VSMCs. In addition, migration assay revealed that ATPgS promoted cell mobility through up-regulation of COX-2 and cPLA 2 expression and PGE 2 release, which was attenuated by pretreatment with PGE 2 receptor antagonists. Taken together, these data showed that ATPgS up-regulated the expression of COX-2 and cPLA 2 through transactivation of PKCd/c-Src/EGFR/PI3K/Akt/Elk-1 pathway. Newly synthesized PGE 2 acted on its receptors to promote cell motility of ATPgS-stimulated VSMCs.