Evolutionary alterations of the minimal promoter for notochord-specific Brachyury expression in ascidian embryos.
Evolutionary alterations of the minimal promoter for notochord-specific Brachyury expression in ascidian embryos.
复制标题
海鞘胚胎中脊索特异性 Brachyury 表达的最小启动子的进化改变。
作者：
Hiroki Takahashi;Yasuo Mitani;G. Satoh;Nori Satoh
两种不同海鞘（Halocynthia roretzi的As-T和Ciona caula的Ci-Bra）的Brachyury基因仅在脊索前体细胞中表达。先前的研究表明，Ci-Bra的脊索特异性表达由最小启动子控制，所述最小启动子由三个不同的区域组成：负责抑制非脊索中胚层细胞中的表达的区域、用于激活脊索细胞中的表达的区域和用于激活非脊索中胚层细胞中的表达的区域，分别位于转录起始位点的远端到近端。我们检查了As-T/lacZ融合基因的各种缺失构建体，并证明5 '侧翼区-289和-250 bp之间的模块负责报告基因的脊索特异性表达。凝胶位移分析表明核蛋白与该模块结合。As-T的5 '侧翼区含有约160 bp的潜在T结合基序（-ACCTAGGT-）。从p（-289）As-T/lacZ中删除该基序会降低报告基因的表达。此外，共注射p（-289）As-T/lacZ和合成的As-TmRNA导致lacZ在非脊索细胞中异位表达，表明T结合基序负责该基因的自激活。这些发现揭示了迄今为止所揭示的As-T和Ci-Bra的最小启动子之间的显著差异，就其脊索特异性表达而言。此外，相互注射的报告基因构建体，即As-T/lacZ到玻璃海鞘卵和Ci-Bra/lacZ到Halocynthia卵，表明顺式调控元件和反式激活因子的变化，发生在两个海鞘物种的进化过程中。
The Brachyury genes of two divergent ascidians, As-T of Halocynthia roretzi and Ci-Bra of Ciona intestinalis, are expressed exclusively in notochord precursor cells. A previous study showed that the notochord-specific expression of Ci-Bra is controlled by a minimal promoter that is composed of three distinct regions: a region responsible for repression of expression in non-notochord mesoderm cells, a region for activation of expression in notochord cells, and a region for activation of expression in non-notochord mesoderm cells, distal to proximal to the transcription initiation site, respectively. We examined various deletion constructs of the As-T/lacZ fusion gene and demonstrate that a module between -289 and -250 bp of the 5'-flanking region is responsible for notochord-specific expression of the reporter gene. Gel-shift assays suggested the binding of nuclear protein(s) to this module. The 5'-flanking region of As-T contains a potential T-binding motif (-ACCTAGGT-) around -160 bp. Deletion of this motif from the p(-289)As-T/lacZ diminished the reporter gene expression. In addition, coinjection of p(-289)As-T/lacZ and synthetic As-T mRNA resulted in ectopic expression of lacZ in non-notochord cells, suggesting that the T-binding motif is responsible for autoactivation of the gene. These findings revealed striking differences between the minimal promoters of As-T and Ci-Bra so far revealed, with respect to their notochord-specific expression. Furthermore, reciprocal injections of reporter gene constructs, namely As-T/lacZ into Ciona eggs and Ci-Bra/lacZ into Halocynthia eggs, suggest alterations in the cis-regulatory elements and trans-activation factors that have occurred during evolution of the two ascidian species.
海鞘追逐尾巴：对脊索动物起源和进化的发育洞察。
DOI：
10.1016/s0168-9525(00)89106-4
发表时间：
1995
期刊：
Trends in genetics : TIG
影响因子：
--
作者：
Satoh,N;Jeffery,WR
通讯作者：
Jeffery,WR
影响因子：
3.5
作者：
FIRE, A;HARRISON, SW;DIXON, D
通讯作者：
DIXON, D