Gan L, Mao C A, Wikramanayake A, Angerer L M, Angerer R C, Klein W H
Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston 77030.
Dev Biol. 1995 Feb;167(2):517-28. doi: 10.1006/dbio.1995.1046.
Orthodenticle-related proteins function as regulators of head formation and other developmental events in flies and mice. Here, we characterize a cDNA clone encoding an orthodenticle-related protein from the sea urchin Strongylocentrotus purpuratus. The cDNA, termed SpOtx, has a highly conserved orthodenticle homeobox but otherwise diverges in sequence from its fly and mouse counterparts. Orthodenticle-related proteins bind with high affinity to DNA containing the sequence motif TAATCC/T. The S. purpuratus aboral ectoderm-specific Spec2a gene has several TAATCC/T sites in its control region, and we provide evidence, using bandshift analysis, that Spec2a may be target gene for SpOtx. Two SpOtx transcripts accumulate during embryogenesis, an early transcript whose level peaks at blastula stage and a late transcript accumulating to highest concentrations at gastrula stage. SpOtx transcripts were found initially in all cells of the cleaving embryo, but they gradually became restricted to oral ectoderm and endoderm cells. In contrast, SpOtx protein was found in nuclei of all cells at both blastula and pluteus stages. Our results suggest that SpOtx plays a role in the activation of the Spec2a gene and most likely has additional functions in the developing sea urchin embryo.
与正齿蛋白相关的蛋白质在果蝇和小鼠中作为头部形成及其他发育事件的调节因子发挥作用。在此，我们鉴定了一个来自紫海胆（Strongylocentrotus purpuratus）的编码与正齿蛋白相关蛋白质的cDNA克隆。该cDNA被命名为SpOtx，具有高度保守的正齿蛋白同源异型框，但在序列上与果蝇和小鼠的对应物有所不同。与正齿蛋白相关的蛋白质以高亲和力结合含有序列基序TAATCC/T的DNA。紫海胆反口外胚层特异性的Spec2a基因在其调控区域有几个TAATCC/T位点，并且我们通过凝胶迁移分析提供了证据，表明Spec2a可能是SpOtx的靶基因。在胚胎发生过程中积累了两种SpOtx转录本，一种早期转录本在囊胚期水平达到峰值，另一种晚期转录本在原肠胚期积累到最高浓度。SpOtx转录本最初在分裂胚胎的所有细胞中被发现，但它们逐渐局限于口外胚层和内胚层细胞。相反，在囊胚期和长腕幼虫期的所有细胞的细胞核中都发现了SpOtx蛋白。我们的结果表明，SpOtx在Spec2a基因的激活中发挥作用，并且很可能在发育中的海胆胚胎中具有其他功能。
