Umbhauer M, Riou J F, Smith J C, Boucaut J C
CNRS URA 1135, Université Pierre et Marie Curie (Paris 6), France.
Dev Dyn. 1994 Aug;200(4):269-77. doi: 10.1002/aja.1002000402.
Tenascin is a large glycoprotein which is expressed in a restricted pattern in the extracellular matrix (ECM) of vertebrate embryos. Tenascin interferes with cell-fibronectin interactions in vitro, and may play a role in the control of cell migration and differentiation during development. In Xenopus, tenascin immunoreactivity is first detected at the early tailbud stage in the ECM of the most anterior somite. Thereafter, it is distributed dorsally along neural crest cell migration pathways. In this paper, we report that tenascin mRNA is most abundant in dorsal mesoderm at the neurula stage and in somites at the early tailbud stage, indicating that the initial accumulation of tenascin in the ECM is due to secretion from paraxial mesoderm. To understand how tenascin expression in somitic mesoderm is controlled, we have expressed Xbra and the myogenic factors XMyoD and XMyf5 in blastula animal cap tissue. The tenascin gene is activated by all three transcription factors. Interestingly, expression of tenascin mRNA, and accumulation of the protein in the ECM, can occur without formation of muscle. Our results suggest that tenascin regionalization in early Xenopus embryos depends on tenascin RNA expression by somitic mesoderm, where it is likely to be activated by myogenic factors.
腱生蛋白是一种大型糖蛋白，在脊椎动物胚胎的细胞外基质（ECM）中以一种受限的模式表达。腱生蛋白在体外会干扰细胞与纤连蛋白的相互作用，并且可能在发育过程中细胞迁移和分化的控制中发挥作用。在非洲爪蟾中，腱生蛋白免疫反应性最早在最前端体节的细胞外基质中的早期尾芽阶段被检测到。此后，它沿着神经嵴细胞迁移途径在背侧分布。在本文中，我们报道腱生蛋白mRNA在神经胚阶段的背侧中胚层和早期尾芽阶段的体节中最为丰富，这表明腱生蛋白在细胞外基质中的最初积累是由于轴旁中胚层的分泌。为了了解体节中胚层中腱生蛋白的表达是如何被控制的，我们在囊胚动物帽组织中表达了Xbra以及成肌因子XMyoD和XMyf5。腱生蛋白基因被所有这三种转录因子激活。有趣的是，腱生蛋白mRNA的表达以及该蛋白在细胞外基质中的积累可以在不形成肌肉的情况下发生。我们的结果表明，非洲爪蟾早期胚胎中的腱生蛋白区域化取决于体节中胚层的腱生蛋白RNA表达，在那里它可能被成肌因子激活。
