Palla F, Bonura C, Anello L, Casano C, Ciaccio M, Spinelli G
Dipartimento di Biologia Cellulare e dello Sviluppo, Consiglio Nazionale delle Ricerche, Palermo, Italy.
Proc Natl Acad Sci U S A. 1993 Jul 15;90(14):6854-8. doi: 10.1073/pnas.90.14.6854.
To shed some light on the mechanisms involved in the coordinate regulation of the early histone gene set during sea urchin development, we tested the hypothesis that the upstream sequence element USE1, previously identified in the early H2A modulator, could also participate in the transcription of the early histone H3 gene. We found by DNAse I protection analysis and by competition in electrophoretic mobility-shift experiments that two sequence elements of the H3 promoter closely resembled the USE1-H2A sequence in their binding activity for nuclear factors from 64-cell stage embryos. These modulator binding factor 1 (MBF-1)-related factors seem to recognize the ACAGA motif that is conserved between the USE1-like sequences of both H2A and H3 promoters. In fact, excess oligonucleotide containing a mutated USE1-H2A element in which the ACAGA sequence was mutated to AGTCA failed to compete with the USE1 sites of both H2A and H3 genes for interaction with MBF-1. Finally, in vivo transcriptional analysis in both Xenopus and sea urchin showed that an excess of USE1-H2A element efficiently competed for the activity of the H3 promoter. From these results we conclude that MBF-1 is a transcription factor conserved between sea urchin and frog and that MBF-1 or related transcription factors are involved in the coordinate expression of both H2A and H3 early histone genes.
为了深入了解海胆发育过程中早期组蛋白基因集协同调控所涉及的机制，我们验证了一个假说，即先前在早期H2A调节剂中鉴定出的上游序列元件USE1，也可能参与早期组蛋白H3基因的转录。我们通过DNA酶I保护分析以及电泳迁移率变动实验中的竞争实验发现，H3启动子的两个序列元件在与64细胞期胚胎核因子的结合活性方面，与USE1 - H2A序列极为相似。这些与调节剂结合因子1（MBF - 1）相关的因子似乎能够识别H2A和H3启动子的类USE1序列中保守的ACAGA基序。事实上，含有突变的USE1 - H2A元件（其中ACAGA序列突变为AGTCA）的过量寡核苷酸无法与H2A和H3基因的USE1位点竞争与MBF - 1的相互作用。最后，非洲爪蟾和海胆的体内转录分析表明，过量的USE1 - H2A元件能够有效竞争H3启动子的活性。从这些结果我们得出结论，MBF - 1是海胆和青蛙之间保守的转录因子，并且MBF - 1或相关转录因子参与H2A和H3早期组蛋白基因的协同表达。
