Possible role of coexpression of CD9 with membrane-anchored heparin-binding EGF-like growth factor and amphiregulin in cultured human keratinocyte growth

✍ Scribed by Shigeki Inui; Shigeki Higashiyama; Koji Hashimoto; Mari Higashiyama; Kunihiko Yoshikawa; Naoyuki Taniguchi

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 203 KB
• Volume: 171
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/(sici)1097-4652(199706)171:3<291::aid-jcp7>3.0.co;2-j

✦ Synopsis

CD9 is a protein with 4 transmembrane domains, and functions as a cell surface antigen. We have previously reported that CD9 functions as an up-regulator of membrane-anchored heparin-binding EGF-like growth factor (proHB-EGF) activity, which is a potent mitogen as well as a soluble HB-EGF. Anti-CD9 antibodies can neutralize the juxtacrine activity of proHB-EGF when both CD9 and proHB-EGF are coexpressed. We demonstrated here: (1) the CD9 gene was transcribed and translated in the cultured human keratinocytes; (2) anti-CD9 antibody inhibited the approximately 50% growth of human keratinocytes in culture; (3) CD9 was coprecipitated with proHB-EGF and membrane-anchored amphiregulin (proAR), and (4) the transient coexpression of CD9 with proHB-EGF or proAR in mouse L cells up-regulated their juxtacrine growth factor activities. These results suggest that CD9 would make a heterodimer and/or trimer complex with proHB-EGF and proAR, and might cooperate with proHB-EGF and proAR for human keratinocyte growth in a juxtacrine manner.