Barberis A, Superti-Furga G, Vitelli L, Kemler I, Busslinger M
Institut für Molekularbiologie II, Universität Zürich, Switzerland.
Genes Dev. 1989 May;3(5):663-75. doi: 10.1101/gad.3.5.663.
We have identified a novel transcription factor that interacts with the promoter of four tissue-specific late histone H2A-2 and H2B-2 genes of the sea urchin by DNase I footprint, mobility shift, and methylation interference analyses. The binding site for this factor is required for efficient transcription of the H2B-2.1 gene both in vitro in nuclear extracts of gastrula embryos and in vivo in microinjected sea urchin embryos. This factor binds with equal affinity to the recognition sequences of all four histone genes in cross-competition assays. Moreover, the binding site of the H2B-2.2 promoter can functionally substitute for that of the H2B-2.1 gene in in vivo expression experiments. Nevertheless, all four binding sites share little sequence homology with each other. This transcription factor increases in abundance during embryogenesis and has been detected in the adult sea urchin only in the tube feet, where the late H2A-2 and H2B-2 genes are expressed specifically. Therefore, we refer to this factor as tissue-specific activator protein (TSAP). The close correlation between the presence of TSAP and the expression pattern of the late H2A-2 and H2B-2 genes suggests that this transcription factor is directly responsible for the developmental and tissue-specific regulation of these genes.
我们通过DNA酶I足迹分析、迁移率变动分析和甲基化干扰分析，鉴定出一种新型转录因子，它与海胆的四个组织特异性晚期组蛋白H2A - 2和H2B - 2基因的启动子相互作用。在原肠胚细胞核提取物的体外实验以及显微注射海胆胚胎的体内实验中，该因子的结合位点对于H2B - 2.1基因的高效转录都是必需的。在交叉竞争实验中，该因子与所有四个组蛋白基因的识别序列具有相同的亲和力。此外，在体内表达实验中，H2B - 2.2启动子的结合位点可以在功能上替代H2B - 2.1基因的结合位点。然而，所有四个结合位点彼此之间几乎没有序列同源性。这种转录因子在胚胎发育过程中丰度增加，并且仅在成年海胆的管足中检测到，晚期H2A - 2和H2B - 2基因在管足中特异性表达。因此，我们将这种因子称为组织特异性激活蛋白（TSAP）。TSAP的存在与晚期H2A - 2和H2B - 2基因的表达模式之间的密切相关性表明，这种转录因子直接负责这些基因的发育和组织特异性调控。
