THE C-KIT RECEPTOR IS INVOLVED IN THE ADHESION OF MOUSE PRIMORDIAL GERM-CELLS TO SOMATIC-CELLS IN CULTURE

The receptor encoded by the W (c-kit) locus is expressed on the membra ne of mouse primordial germ cells, whereas its ligand termed stem cell factor (SCF), encoded by the SI locus, is expressed on the membrane o f somatic cells associated with both the primordial germ cell migrator y pathways and homing sites. Using an in vitro short time assay which allows a quantitative measure of adhesion between cells, in the presen t paper we show that SCF/c-kit interaction can modulate primordial ger m cell adhesion to somatic cells. We report that the adhesiveness of 1 1.5 dpc primordial germ cells to four types of somatic cells in cultur e (TM4 cells, STO fibroblasts, bone marrow stromal cells and gonadal s omatic cells) is significantly reduced by antibodies directed against c-kit receptor or SCF, as well by soluble SCF. This SCF/c-kit mediated adhesion seems independent of SCF-induced tyrosine autophosphorylatio n of c-kit receptor. Moreover, primordial germ cells showed a poor abi lity to adhere to a bone marrow stromal cell line carrying the Sl(d) m utation (unable to synthesize membrane-bound SCF). This adhesiveness w as not further impaired by anti-c-kit antibody. These results demonstr ate that SCF/c-kit interaction contributes to the adhesion of primordi al germ cells to somatic cells in culture and suggest that the role pl ayed by SCF in promoting survival, proliferation and migration of thes e cells in vitro and in vivo, demonstrated by several studies, might d epend on the ability of the membrane-bound form of this cytokine to di rectly mediate primordial germ cell adhesion to the surrounding somati c cells. (C) 1997 Elsevier Science Ireland Ltd.