Ransom D G, Hens M D, DeSimone D W
Department of Anatomy and Cell Biology, University of Virginia, Charlottesville 22908.
Dev Biol. 1993 Nov;160(1):265-75. doi: 10.1006/dbio.1993.1304.
During embryogenesis cells modulate their adhesion to other cells and the surrounding extracellular matrix, in part, through the combination of integrins they express. In order to identify integrins that may mediate morphogenetic cell movements in the early Xenopus embryo, we have used polymerase chain reaction methods to isolate cDNAs encoding Xenopus integrin beta subunits. Based on deduced amino acid sequence, they are identified as homologs of human integrins beta 1, beta 2, beta 3 and beta 6. We also report the cloning and sequencing of cDNAs covering the complete coding region of Xenopus beta 3. Embryonic patterns of expression for these integrin beta subunit mRNAs have been examined both by RNase protection analysis and by whole mount in situ hybridization. In the early embryo the beta 1 subunit is encoded by a maternally transcribed mRNA expressed in all cells, but is most abundant in ectoderm and mesoderm. In contrast, Xenopus beta 3 mRNA is detected in the epidermis, bottle cells of the neural groove, and a subset of cells arising from the ventral blood islands. The beta 2 and beta 6 mRNAs are expressed at high levels in late tailbud stages, although very low levels of beta 6 are also detected in eggs and early embryos. These data provide evidence that multiple integrins are expressed at the earliest stages of vertebrate development coincident with the onset of morphogenesis.
在胚胎发生过程中，细胞部分地通过它们所表达的整合素的组合来调节其与其他细胞及周围细胞外基质的黏附。为了鉴定可能介导非洲爪蟾早期胚胎中形态发生细胞运动的整合素，我们使用聚合酶链反应方法分离编码非洲爪蟾整合素β亚基的cDNA。根据推导的氨基酸序列，它们被鉴定为人整合素β1、β2、β3和β6的同源物。我们还报告了覆盖非洲爪蟾β3完整编码区的cDNA的克隆和测序。这些整合素β亚基mRNA的胚胎表达模式已通过核糖核酸酶保护分析和整体原位杂交进行了检测。在早期胚胎中，β1亚基由在所有细胞中表达的母源转录mRNA编码，但在外胚层和中胚层中最为丰富。相比之下，非洲爪蟾β3 mRNA在表皮、神经沟的瓶状细胞以及来自腹侧血岛的一部分细胞中被检测到。β2和β6 mRNA在尾芽后期高水平表达，尽管在卵和早期胚胎中也检测到非常低水平的β6。这些数据提供了证据，表明多种整合素在脊椎动物发育的最早阶段表达，与形态发生的开始同时发生。
