Abstract: Objective：To construct OCIL shRNA expression construct and to study its effects on RANKL/OPG expression in osteoblasts and on osteoclastogenesis. Methods：Small hairpin RNA (shRNA) coding sequences targeting rat OCIL mRNA were designed, synthesized and cloned into pRNAT-U6.1/Neo vector. The constructs were transfected into UMR106 cell line with lipofectamine 2000. The expression level of OCIL mRNA in the cells was determined by real-time quantitative RT-PCR. The expression levels of RANKL and OPG were also studied. The culture medium collected from the transfectant was used to treat rat bone marrow cells in the presence of PTH and the number of osteoclast like cells formed from marrow cells were scored. Results：The shRNA expression constructs significantly reduced OCIL mRNA in UMR106 cells after transfection. Moreover, the overexpression of OCIL shRNA resulted in a significant increase of RANKL mRNA and decrease of OPG mRNA. The culture medium collected from the transfectant promoted osteoclast-like cell formation from marrow cells in the presence of PTH. Conclusion：The inhibition of osteoclastogenesis by OCIL may involve the regulation of RANKL/OPG system.

Key words: osteoclast inhibitory lectin(OCIL), shRNA, receptor activator of nuclear factor κB ligand (RANKL), osteopmtegerin(OPG), osteoblast