Objective         To determine the effect of Geminin in the phenotypic transformation of rat vascular smooth muscle cells (VSMCs).       Methods        After an eucaryotic plasmid vector pEGFP-N1-Geminin was constructed

VSMCs strains of different phenotypes (dedifferentiated phenotype by cultured in present of serum

and differentiated phenotype by cultured without serum) were transfected with aid of lipofectamine 2000. Cells transfected with pEGFP-N1 and blank plasmids served as negative control and blank control. The expression of  Geminin

actin related protein 1 (ARP1)

and VSMCs phenotypic makers α-actin and osteopontin (OPN) were detected with Western blotting. The interaction between Geminin and ARP1 were analyzed with co-immunoprecipitation.       Results        Geminin was successfully overexpressed in VSMCs strains after transfection. Comparing with negative and blank controls

Geminin overexpression resulted in obviously down-regulation of OPN protein in the dedifferentiation cells

but significantly up-regulation in α-actin and ARP1 (P0.05). However

these changes of above-mentioned markers and ARP1 were not significantly changed in differentiated cells. Co-immunoprecipitation indicated that interaction between Geminin and ARP1 was found in Geminin-overexpressed VSMCs strains with dedifferentiated phenotype.       Conclusion         Geminin may play a role in the phenotypic transformation of VSMCs from dedifferentiation to differentiation. The interaction between Geminin and ARP1 suggests that ARP1 may be involved in this process.