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Objective: To observe the direct regulation of miR-127 on Bcl-6 and the effect of Bcl-6 in rescuing miR-127-induced cell cycle and cell growth inhibition., Methods: The 3'UTR and coding region of human bcl-6 gene were amplified by PCR and cloned into pcDNA3.0-Luc and pcDNA3.0-Flag vectors, respectively. Mutations were introduced into the seed sequences of the predicted miR-127 target sites within the Bcl-6 3'UTR using recombinant PCR. Luciferase assay was used to verify the direct targeted regulation of miR-127 on Bcl-6. In HepG2 cell models with overexpression or knockdown of miR-12, the changes of cell cycle and cell growth were investigated after transfection with the constructed vectors., Results: The recombinant plasmids were successfully obtained as confirmed by double digestion and sequence identification. Luciferase assay showed that in 293T and HepG2 cells, miR-127 inhibited the activation of wild-type Bcl-6 3'UTR reporter vector but not mutated Bcl-6 3'UTR vector. Overexpression of miR-127 induced cell cycle arrest at G(2)/M phase and suppressed the growth of HepG2 cells, and these effects were reversed by Bcl-6 overexpression., Conclusion: We successfully cloned wild-type and mutated 3'UTR reporter vectors and expression vector of bcl-6 gene and confirmed their biological functions.

Aim: To clone prokaryotic expression vector of Cdc25C, purify the fusion protein of GST-Cdc25C, and identify its function preliminarily., Methods: Human Cdc25C coding region was amplified from human mammary cDNA library by PCR, and cloned into the prokaryotic expression vector pGEX-KG. The fusion protein GST-Cdc25C was expressed in E.coli Rossate and purified by GST-Sepharose 4B beads. The function of purified GST-Cdc25C was identified by GST pull-down assay., Results: The GST-Cdc25C recombinant plasmid was successfully obtained by double digestion identification. The inserted fragment was confirmed correctly by sequencing. SDS-PAGE and Western blot analysis showed that the fusion protein was expressed. The fusion protein of about M(r); 80 000 was successfully induced, and identified by SDS-PAGE and Western blot analysis. GST pull-down assay showed that GST-Cdc25C could interact with Chk2 which verified its known function., Conclusion: Cdc25C was successfully cloned and purified.

Objective: To investigate whether progesterone receptor B (PRB) can be sumoylated by SUMO-2/3 and the effect of sumoylation on PRB transcriptional activity., Methods: SUMO-2/3 cDNA was amplified from MCF-7 cDNA and cloned into the eukaryotic expression vector pcDNA3-FLAG. The plasmid pXJ40-myc-PRB was cotransfected with pcDNA3FLAG-SUMO2, pcDNA3FLAG-SUMO3 or the mock control into 293T cells, and PRB sumoylation was detected by immunoprecipitation and Western blotting. The effect of PRB sumoylation on its transcriptional activity was determined using reporter luciferase assay., Results: pcDNA3FLAG-SUMO2 and pcDNA3FLAG-SUMO3 vectors were successfully constructed. SUMO-2/3 could bind covalently to PRB and increase its transcriptional dependent on the presence of progesterone., Conclusion: PRB can be sumoylated by SUMO-2/3 and its function is regulated by this modification.