Expression and function of blimp1/krox, an alternatively transcribed regulatory gene of the sea urchin endomesoderm network
Expression and function of blimp1/krox, an alternatively transcribed regulatory gene of the sea urchin endomesoderm network
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DOI：
10.1016/j.ydbio.2006.02.021
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发表时间：
2006-05-15
影响因子：
2.7
通讯作者：
Davidson, Enic H.
中科院分区：
文献类型：
--
作者：
Livi, Carolina B.;Davidson, Enic H.
紫球藻的blimp1/KROX基因编码锌指转录因子，在早期和晚期的内胚层规范中都起着重要的作用。在这里，我们展示了在不同调控区域的控制下转录的两种不同的剪接形式。Blimp1/krox1b形式以前是未知的，是在卵裂期间表达的形式，开始于受精后6-9h。对于内胚层规范的早期事件，此表是必需的。不同的剪接变异体blimp1/krox1a仅在原肠胚期以后表达。在卵裂阶段，blimp1/KROX基因在大的微粒和VEG2后代中表达。不久之后，它在胚泡的营养极特定的中胚层细胞环中表达。后来，它的表达仅限于胚孔区和内陷原肠的后部，最后表达到海鞘幼虫的中肠和后肠。BLIMPI/KROX的表达是动态的，涉及几个不同的空间区域。用GFP编码序列替代第二外显子(1b)，构建了GFP重组BAC，以区分早期和晚期的表达模式。这个结构与海胆发育早期的blimp1/krox1b表达非常相似。为了扩大我们对该基因下游连接的了解，使用反义吗啉寡核苷酸(Maso)进行了额外的实验。我们证实了之前发表的数据，即blimp1/KROX自动调节自己的表达，但令人惊讶的是，该基因抑制而不是激活自己。对Maso注射的胚胎进行的原位杂交分析表明，这种负的自我调节仅限于囊胚期的中胚层，可能还包括骨骼发育区域。Maso干扰分析还显示，blimp1/KROX基因进入了内胚层调控网络的其他基因。(C)2006 Elsevier Inc.保留所有权利。
The blimp1/krox gene of Strongylocentrotus purpuratus, formerly krox1, encodes zinc finger transcription factors which play a central role in both early and late endomesoderm specification. Here we show that there are two alternative splice forms transcribed under the control of different regulatory regions. The blimp1/krox1b form was previously unknown, and is the form expressed during cleavage, beginning 6-9 h postfertilization. This form is required for the early events of endomesoderm specification. A different splice variant, blimp1/krox1a, is expressed only from gastrula stage onward. During cleavage stages the blimp1/krox gene is expressed in the large micromeres and veg2 descendents. Soon after, it is expressed in the ring of specified mesoderm cells at the vegetal pole of the blastula. Its expression is later restricted to the blastopore region and the posterior of the invaginating archenteron, and finally to the midgut and hindgut of the pluteus larva. The expression of blimpI/krox is dynamic, and involves several distinct spatial territories. A GFP recombinant BAC was created by substituting the GFP coding sequence for that of the second exon (1b), in order to distinguish the expression pattern of the early form from that of the late form. This construct closely mimics blimp1/krox1b expression during early stages of sea urchin development. To expand our knowledge of the downstream linkages of this gene, additional experiments were carried out using antisense morpholino oligos (MASO). We confirmed previously published data that blimp1/krox autoregulates its own expression, but discovered, surprisingly, that this gene represses rather than activates itself. This negative autoregulation is restricted to the mesodermal and probably skeletogenic territories during the blastula stage, as shown by in situ hybridization analysis of MASO injected embryos. The MASO perturbation analysis also revealed blimp1/krox inputs into other genes of the endomesoderm regulatory network. (c) 2006 Elsevier Inc. All rights reserved.