The Research Of The Biological Function Of Human Novel Gene BNIPL

Cell proliferation and apoptosis are the two essential opposite cellular processes. Both of the processes are physiologically closely associated and regulated. Their coordination and balance are crucial for governing both homeostasis and normal development of cells and tissues. Deregulated cell proliferation and suppressed apoptosis constitute the minimal common platform upon which cancer and autoimmune diseases occur.Bcl-2/adenovirus E1B 19 kDa interacting protein 2 like, BNIP-2 like (BNIPL) is a recently cloned protein. It was found that there are 5 BNIPL variants, and two full-length cDNA named BNIPL-v1 and BNIPL-v2 were obtained by SMART-RACE strategy. BNIPL-v1 and BNIPL-v2 encode 357 amino acids and 275 amino acids respectively, and their Genbank accession numbers are AY033000 and AF193056 respectively. It was found that BNIPL-v1and BNIPL-v2 share 68% and 72% homology with BNIP-2, respectively. BNIPL has two conserved domain named SEC14 domain and BCH domain.Genome orientation of BNIPL gene is 1q21.1. BNIPL subcellular located in cytoplasm and it is highly expressed in human placenta and lung. Although BNIPL has a SEC14 domain, the deletion of sec14 has not been complemented by BNIPL in Saccharomyces cerevisiae. A yeast two-hybrid system was used to obtain four BNIPL-interacting proteins: MIF, GFER, nm23-H2 and FKBP38. The interactions were confirmed by GST pull-down assay in vitro and co-immunoprecipitation assay in vivo. BNIPL interacted with MIF, GFER, nm23-H2 and FKBP38 on the region of C-terminal 157-357 amino acids on BNIPL-v1, respectively. Colony formation assay and cell proliferation test suggest that overexpression of BNIPL could inhibit the growth of BEL-7402 and Hep3B cells. BNIPL can induce apoptosis of Hep3B cells by detecting PS externalization with FCM.BNIPL and its interacting-protein FKBP38 can directly bind to Bcl-2, respectively. It is implied that BNIPL induced apoptosis by taking part in the regulation of the interaction or the co-localization of FKBP38-Bcl-2 complex. The Hep3B cell lines, expressing BNIPL and MIF or nm23-H2, were established to investigate the biological functions of the interactions between BNIPL and MIF or nm23-H2, in which the expression of BNIPL is induced by Dox. FCM were performed to detect the apoptosis and cell cycle of the Hep3B cells. The results showed that BNIPL and nm23-H2, both having pro-apoptosis function, were in two different pathways upstream the Bcl-2. When they interacted with each other, the two pathways were blocked at the same time and the Hep3B cells were rescued from apoptosis. BNIPL also takes part in the regulations of cell proliferation by interacting with the two cell proliferation-related proteins, MIF and GFER.All these findings suggest that BNIPL may play an important role in the regulation network of cell proliferation and apoptosis.