ESTROGEN REGULATION OF LRP16 GENE EXPRESSION INVOLVES SP1 TRANSCRIPTION FACTOR

Objective： To investigate the role of Spl as transcription factor required for transactivation of LRP16 gene by estrogen. Methods： Specific antibodies of ERα and Spl were used to precipitate the target DNA/protein complexes of MCF-7 cells at different time points after estrogen treatment （Chromatin immunoprecipitation assay）, the promoter region of LRP16 gene was amplified by semi-nested polymerase chain reaction （snPCR）. Small interfering RNA （siRNA） against Spl was transiently cotransfected with LRP16-Luc （containing the region from -213bp to -126bp of LRP16 gene promoter）in MCF-7 cells. The luciferase activities were measured by dual-luciferase assay. Results： The results of chromatin immunoprecipitation assay showed that Spl protein directly bound to the -213bp to -126bp region of LRP16 gene, and ERα could enhance the affinity of Spl to DNA. Spl-siRNA specifically decreased the transactivation of LRP16-Luc by 1713-estradio1 to 70-80%. Conclusion： The estrogen-induced transactivation of the human LRP16 gene was mediated by Spl protein. Moreover, the interactions of ERα/Sp1 functional complex with LRP16 promoter DNA were required for enhanced LRP16 gene transactivation.