Transient, Localized Accumulation of α-Spectrin during Sea Urchin Morphogenesis
Transient, Localized Accumulation of α-Spectrin during Sea Urchin Morphogenesis
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海胆形态发生过程中 α-血影蛋白的瞬时、局部积累
DOI：
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
Siming W. Chen
中科院分区：
文献类型：
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作者：
G. Wessel;Siming W. Chen
海胆胚胎α-谱蛋白mRNA和蛋白在细胞中短暂过表达，引发一定的形态发生变化。利用从Lytechinus variegatus cDNA文库中分离的α-spectrin编码的4.5 kb cDNA克隆检测了该表达。DNA序列分析表明，该cDNA与人非红系α-spectrin相似度达80%。海胆α-谱蛋白RNA在胚胎的所有细胞中积累到统一的基础水平，在原肠胚形成前植物板的初代间质细胞中积累明显增加。在原肠形成过程中，内胚层细胞也表达更高水平的谱蛋白，这些水平在将肠道分为前肠、中肠和后肠的括约肌收缩区肌上皮细胞中保持较高水平。利用大肠杆菌合成的重组海胆光谱蛋白抗体原位定位该蛋白。这些实验表明，胚胎的所有细胞积累α-谱蛋白局限于细胞-细胞接触的皮质区域。在上皮细胞中，这种定位表现为明显的蜂窝状。原代间充质细胞和肠括约肌肌上皮细胞的谱蛋白信号明显增强，与原位RNA杂交观察到的明显的RNA定位模式相对应。这些数据表明，海胆α-spectrin是光谱蛋白超家族中高度保守的成员，其在特定细胞类型中的表达升高预示了明显的形态发生。
Abstract The mRNA and protein of α-spectrin in the sea urchin embryo is shown here to be transiently overexpressed in cells initiating certain morphogenetic changes. This expression was detected by use of a 4.5-kb cDNA clone that encodes α-spectrin isolated from a Lytechinus variegatus cDNA library. DNA sequence analysis demonstrated 80% similarity of this cDNA to human nonerythroid α-spectrin. Sea urchin α-spectrin RNA accumulated to a uniform basal level in all cells of the embryo with a marked, transient increased accumulation in the primary mesenchyme cells of the vegetal plate just prior to gastrulation. Cells of the endoderm also express increased levels of spectrin during gastrulation and these levels remained high in the myoepithelial cells of the sphincter constrictions that separates the gut into foregut, midgut, and hindgut domains. Antibodies made to recombinant sea urchin spectrin synthesized in Escherichia coli were used to localize the protein in situ . These experiments showed that all cells of the embryo accumulated α-spectrin protein confined to the cortical regions of cell-cell contact. In epithelial cells, this localization showed a distinct honeycomb pattern. Primary mesenchyme cells and the myoepithelial cells of the gut sphincters showed significantly enhanced spectrin signal corresponding to the pronounced RNA localization pattern seen by in situ RNA hybridization. These data demonstrated that α-spectrin from the sea urchin is a highly conserved member of the spectrin superfamily of proteins and that its elevated expression in specific cell types anticipates overt morphogenesis.