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BH4 Domain (bh4 + domain)
Selected AbstractsBH4 peptide derived from Bcl-xL and Bax-inhibitor peptide suppresses apoptotic mitochondrial changes in heat stressed bovine oocytesMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 7 2009Paolete Soto Mitochondria play an important role in the integration and transmission of cell death signals mediated by the Bcl-2 family proteins. Experiments were conducted to determine whether the anti-apoptotic peptides BH4 domain of Bcl-xL (TAT-BH4) and Bax inhibitor peptide (BIP) suppresses heat stress (HS) injury in oocytes by reduction of apoptotic-like events. Cumulus,oocyte complexes (COCs) were matured at 39°C (control) or 41°C (HS) for 21 hr then placed in maturation medium containing 0 or 100 µM BIP in water and 0 or 1 µM TAT-BH4 in dimethyl sulfoxide (DMSO), or a combination of both peptides (BIP,+,BH4). Peptide effects on embryo development, DNA fragmentation, mitochondrial membrane potential (,,m), and mitochondrial DNA (mtDNA) copy number were measured. All groups were fertilized and cultured in vitro at 39°C for 8 days. Compared to control, HS-treated oocytes induced a decrease in embryo development (P,<,0.05), increase in proportion of TUNEL-positive chromatin in oocytes and blastocysts (P,<,0.05), and loss of oocyte ,,m (P,<,0.001). In the presence of BIP or BIP,+,BH4, development of HS-treated oocytes into blastocysts was increased (P,<,0.05). Conversely, COCs matured with TAT-BH4 at 41°C showed reduced embryonic development (P,<,0.05). Exposure of HS-treated to each or both peptides resulted in a reduction of TUNEL frequency in oocytes and blastocysts cells derived from these oocytes (P,<,0.05). The loss of ,,m in HS-treated oocytes was not restored by exposure to BIP,+,BH4 and there was no effect in mtDNA copy number. In conclusion, the present results show that HS-induced apoptosis in bovine oocytes involves Bax and BH4 domain-dependent pathways. Mol. Reprod. Dev. 76: 637,646, 2009. © 2008 Wiley-Liss, Inc. [source] The role of various Bcl-2 domains in the anti-proliferative effect and modulation of cellular glutathione levels: a prominent role for the BH4 domainCELL PROLIFERATION, Issue 1 2003R. W. M. Hoetelmans Reduced cell proliferation and increased levels of cellular glutathione (GSH) are characteristic for cells that overexpress the anti-apoptotic Bcl-2 protein. We investigated the influence of various Bcl-2 domains on both these characteristics. Rat CC531 colorectal cancer cells were stably transfected with the human bcl- 2 gene (CCbcl2 cells) or with bcl- 2 gene constructs missing a coding sequence for a func-tional domain, BH1 (CC,BH1 cells), BH3 (CC,BH3 cells), BH4 (CC,BH4 cells) or the transmembrane region (CC,TM cells). We measured GSH levels in exponentially and confluent growing bcl- 2-transfected cell populations. The fraction of S-phase cells during exponential growth was significantly reduced in CCbcl2, CC,BH1, CC,BH3, and CC,TM cells compared with parental CC531, neo-transfected CC531 and CC,BH4 cells. GSH levels in these bcl -2 transfectants were significantly higher than in the parental line measured at 50% confluence; at 100% confluence they reached a similar level as found in parental cells. Independently from the presence of BH1, BH3 or TM domains, overexpression of Bcl-2 reduces cellular proliferation under conditions of increased GSH levels. This apparent link is lost in CC,BH4 cells; these cells are not reduced in cellular proliferation and harbour significantly higher GSH levels than found in the other transfectants. Studies on the subcellular localization revealed an extremely low expression of the Bcl-2 protein lacking the N-terminal BH4 domain in nuclear fractions. Nuclear translocation of Bcl-2 requires the presence of the BH4 domain and seems prominent in reducing cellular proliferation. [source] | ||||||||||