MOLECULAR-CLONING AND CHARACTERIZATION OF RGC-32, A NOVEL GENE INDUCED BY COMPLEMENT ACTIVATION IN OLIGODENDROCYTES

Sublytic complement activation on oligodendrocytes (OLG) down-regulate s expression of myelin genes and induces cell cycle in culture. Differ ential display (DD) was used to search for new genes whose expression is altered in response to complement and that may be involved in cell cycle activation. DD bands showing either increased or decreased mRNA expression in response to complement were identified and designated Re sponse Genes to Complement (RGC) 1-32, RGC-1 is identical with heat sh ock protein 105, RGC-2 with poly(ADP-ribose) polymerase, and RGC-10 wi th IP-10, A new gene, RGC-32, that encodes a protein of 137 amino acid s was cloned. RGC-32 has no homology with other known proteins, and co ntains no motif that would indicate its function. In OLG, the mRNA exp ression was increased by complement activation and by terminal complem ent complex assembly. RGC-32 protein was localized in the cytoplasm an d co-immunoprecipitated with cdc2 kinase. Overexpression of RGC-32 inc reased DNA synthesis in OLGxC6 glioma cell hybrids. These results sugg est that RGC-32 may play a role in cell cycle activation.