Gene identification and functional analysis of a D-type cyclin (CCND2) in freshwater pearl mussel (Hyriopsis cumingii)

Background Cyclin D (CCND) plays an important role in the cell cycle and is a rate-limiting factor that facilitates the G1/S transition. Methods In this study, the full-length cDNA of Hc-CCND2 was isolated from freshwater pearl mussel ( Hyriopsis cumingii ; Hc ) and amplified using the 3´/5´ RACE system. The Hc-CCND2 expression profiles were analysed by quantitative real-time PCR. Functional analysis of the Hc-CCND2 genes was examined by both RNA interference (RNAi) and overexpression in H. cumingii . Results Hc-CCND2 protein sequences were 295 amino acids long, possessed D-type cyclin signature motifs and contained conserved cyclin box domains. Hc-CCND2 was expressed in all examined tissues (adductor, foot, visceral mass, gill, outer mantle, inner mantle and gonad), with the highest expression levels found in the gill ( P