植物HAP3转录因子研究进展

HAP(NF-Y或CBF)是一类重要的转录因子,可以与CCAAT框结合并控制基因的表达,广泛分布于酵母、哺乳动物及植物细胞中.在哺乳动物和植物细胞中,HAP复合体包括3个不同的亚基:HAP2/NF-YA/CBF-B、HAP3/NF-YB/CBF-A及HAP5/NF-YC/CBF-C.HAP3转录因子在植物胚胎发育、叶绿素生物合成、花期调控等方面有重要作用.介绍植物HAP3转录因子结构特点、生物学功能等方面的最新研究进展.     

The CCAAT-binding factor CBF/NF-Y regulates the human acetylcholinesterase promoter activity during calcium ionophore A23187-induced cell apoptosis

We previously reported that the expression of acetylcholinesterase during A23187-induced apoptosis of HeLa cells is regulated by Ca(2+) mobilization through the modulation of mRNA stability and acetylcholinesterase promoter activity. Transactivation of the human acetylcholinesterase promoter by A23187 was partially mediated by the distal CCAAT motif within the -1270 to -1248 fragment of the human acetylcholinesterase promoter, which was bound by the CCAAT binding factor (CBF/NF-Y). In the present study, we investigated the molecular mechanisms by which CBF/NF-Y regulates A23187-induced activation of the human acetylcholinesterase promoter. The results indicate that CBF/NF-Y binding to the distal CCAAT motif suppresses the promoter activity. Electrophoretic mobility shift assays (EMSAs) demonstrated that binding of CBF/NF-Y to the distal CCAAT motif decreased after A23187 treatment. Our results suggest that acetylcholinesterase promoter activation during A23187-induced HeLa cell apoptosis may result partly from the dissociation of CBF/NF-Y from the distal CCAAT motif in the acetylcholinesterase promoter, reversing this suppression.     

Recombinant AtNF-YA, a subunit of theArabidopsis CCAAT-binding transcription factor, forms a protein-DNA complex with mammalian NF-YB and NF-YC

The evolutionary conserved CCAAT binding protein NF-Y is a common regulatory DNA binding protein consisting of three distinct subunits. Unlike yeast and mammals, in which only a single copy of each subunit is encoded,Arabidopsis encodes a multi-gene family for each subunit in its genome. Compared with the NF-Y of mammals or yeast, very little is known about plant NF-Y homologs. HereArabidopsis NF-YA subunits were isolated to determine whether they could form a hete-rotrimeric NF-Y complex with mammalian NF-YB and NF-YC. This resultant chimeric NF-Y complex had DNA binding ability to the same CCAAT sequences as those of the other life systems. Therefore, it is possible that plant NF-Y homologs might have biochemical characteristics similar to mammalian NF-Y, thereby suggesting its functional conservation among organisms.