The Rep68 protein of adeno-associated virus type 2 stimulates expression of the platelet-derived growth factor B c-sis proto-oncogene.

Rep68 protein, encoded by adeno-associated virus type 2 (AAV), has been previously shown to bind to specific sequences within the viral genome and in human chromosome 19. The effect of AAV Rep protein on human cellular genes is of interest because AAV is being developed as a gene therapy vector. We have identified sequences related to the Rep recognition sequence in the AAV P5 promoter in or near the c-sis proto-oncogene and the genes coding for a hepatocyte glucose transporter, alpha-A-crystallin, and carcinoma marker GA733-1. The ability of Rep68 to bind to these sites was established by gel shift assays, and the effect of Rep68 on the expression of these genes was tested by semiquantitative reverse transcriptase PCR. Rep68 enhances the expression of the c-sis proto-oncogene, which codes for the B polypeptide of platelet-derived growth factor, a multifunctional growth factor that is involved in embryonic development, tissue regeneration, osteogenesis, fibrosis, atherosclerosis, and neoplasia.