CD9 is expressed on the cell surface of human granulosa cells and associated with integrin alpha61

Abstract

The CD9 molecule is a 24–27 kDa cell surface glycoprotein which is reported to be involved in cell adhesion and migration. Recently, CD9 was shown to be associated with β₁-related integrins. We have previously found that integrin α₆β₁ is expressed on human granulosa cells (GC) and regulates luteinization of GC in concert with its ligand laminin. In this study, we examined the expression of CD9 in human ovary and the relationship between CD9 and integrin α₆β₁ in GC. By immunohistochemistry, CD9 was detected on GC in a small antral follicle of CD9 mRNA was also detected in the isolated GC and CL by reverse transcription–polymerase chain reaction (RT–PCR). The proteins purified from GC by immunoaffinity chromatography using anti-integrin α₆ monoclonal antibodies were shown by Western blotting to include CD9 as well as integrin β₁. These findings suggest that CD9 is a differentiation-related molecule of GC and TI and that it is associated with integrin α₆β₁ on the cell surface of GC, suggesting that CD9 is implicated in the function of human GC in cooperation with integrin α₆β₁.