| BAMBI(BMP and Activin Membrane-bound Inhibitor)is a suppressive pseudoreceptor on the transforming growth factor-β(TGF-β)pathway,which competes with TGF-β type I receptor for binding ligands and TGF-β type II receptor complex and inhibits the signal transduction of the TGF-β pathway.Recent studies in intractable diseases like cancer have found that the regulation of BAMBI in the TGF-β pathway is crucial,especially in ovarian cancer,but its function in oocyte development is still unknown.In order to explore the effect of gene BAMBI on the development of oocytes and embryos,different gene overexpression patterns were used in this experiment.The effects of gene BAMBI on oocyte development were verified from the perspective of direct and indirect ways.And then its regulation mechanism was investigated.The results showed as follow:(1)BAMBI gene can promote the maturation of oocytes while inhibiting the proliferation and attachment of peripheral cumular cells,but it also promoted the migration of cumular cells.(2)In a separate co-culture experiment with cumular cells and oocytes,we found that disrupting the gap junctions between cumular cells and oocytes affected the effect of BAMBI,so,this indirect effect was dependent on gap junctions.(3)The BAMBI gene was cloned in vitro,and connected to a eukaryotic vector and post-transcriptionally injected with GV(immature biofoam)oocytes,and it was found that the BAMBI gene also promoted oocyte maturation.(4)Compared with TGF-β inhibitors,culture experiments showed that BAMBI was different from inhibitors on the SMAD2/3 sub-pathway,but similar to the inhibition of the SMAD1/5/8 sub-pathway,suggesting that BAMBI inhibited the main role of the SMAD1/5/8 sub-pathway and leaded to the oocyte maturation.Therefore,we believe that SMAD2/3 and SMAD1/5/8 in the TGF-β pathway play a counter-regulatory role during oocyte development.In conclusion,the BAMBI gene can inhibit the proliferation and adherence ability of cumular cells by direct and indirect way that inhibiting the TGF-β pathway on the oocyte,but promoting its ability to disperse migration,and thus promote oocyte maturation.This regulation is due to the fact that BAMBI competitively inhibits the signal transduction of the TGF-β pathway and promotes oocyte maturation through the inhibition of SMAD1/5/8 subunit pathway.Although BAMBI can promote the maturation of oocytes,its regulatory mechanism and the role of TGF-β pathway in oocyte and post-embryonic development need to be further verified by experiments.These studies will be gradually improved during the continuous development of medical science and technology,which will provide a theoretical basis for the advancement of human medicine. |
