Cheers Melani S, Ettensohn Charles A
Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
Dev Biol. 2005 Jul 15;283(2):384-96. doi: 10.1016/j.ydbio.2005.02.037.
The primary mesenchyme cells (PMCs) of the sea urchin embryo undergo a dramatic sequence of morphogenetic behaviors that culminates in the formation of the larval endoskeleton. Recent studies have identified components of a gene regulatory network that underlies PMC specification and differentiation. In previous work, we identified novel gene products expressed specifically by PMCs (Illies, M.R., Peeler, M.T., Dechtiaruk, A.M., Ettensohn, C.A., 2002. Identification and developmental expression of new biomineralization proteins in the sea urchin, Strongylocentrotus purpuratus. Dev. Genes Evol. 212, 419-431). Here, we show that one of these gene products, P16, plays an essential role in skeletogenesis. P16 is not required for PMC specification, ingression, migration, or fusion, but is essential for skeletal rod elongation. We have compared the predicted sequences of P16 from two species and show that this small, acidic protein is highly conserved in both structure and function. The predicted amino acid sequence of P16 and the subcellular localization of a GFP-tagged form of the protein suggest that P16 is enriched in the plasma membrane. It may function to receive signals required for skeletogenesis or may play a more direct role in the deposition of biomineral. Finally, we place P16 downstream of Alx1 in the PMC gene network, thereby linking the network to a specific "effector" protein involved in biomineralization.
海胆胚胎的初级间充质细胞（PMC）经历了一系列显著的形态发生行为，最终形成幼虫内骨骼。最近的研究已经确定了一个基因调控网络的组成部分，该网络是PMC特化和分化的基础。在之前的工作中，我们鉴定了由PMC特异性表达的新基因产物（Illies, M.R., Peeler, M.T., Dechtiaruk, A.M., Ettensohn, C.A., 2002. 海胆Strongylocentrotus purpuratus中新型生物矿化蛋白的鉴定及发育表达。发育基因与进化。212, 419 - 431）。在这里，我们表明这些基因产物之一P16在骨骼发生中起重要作用。P16对于PMC的特化、内陷、迁移或融合不是必需的，但对于骨骼杆的伸长是必不可少的。我们比较了两个物种中P16的预测序列，并表明这种小的酸性蛋白在结构和功能上都高度保守。P16的预测氨基酸序列以及该蛋白的GFP标记形式的亚细胞定位表明P16在质膜中富集。它可能起到接收骨骼发生所需信号的作用，或者可能在生物矿质沉积中发挥更直接的作用。最后，我们将P16置于PMC基因网络中Alx1的下游，从而将该网络与参与生物矿化的特定“效应器”蛋白联系起来。
