Extracellular Matrix Induction of Primary Mesenchyme Differention

海胆微粒在胚胎的植物极由四个细胞的植物层不均匀分裂产生。初代间充质，微粒的分裂产物，迁移到胚胎的囊胚腔，在那里它们与细胞外基质（ECM）相互作用并分化产生胚胎骨架或针状体。来自体外和体内研究的证据表明，微粒需要一个允许的环境或信号来启动分化。完整的胚胎外基质是发育环境的重要组成部分。PI最近表明，如果在重建的基板（基质）上培养，微粒将在体外分化。单独在海水中培养的微粒菌不会分化。母体中启动分化的分子是什么？它与胚胎中的内源性信号分子有何关系？本项目拟：(1)从基质中鉴定纯化出针状诱导活性（SIA）；(2)鉴定出SIA的一般作用机制；(3)从海胆胚胎中鉴定并初步鉴定出同源的SIA活性。

Sea urchin micromeres arise at the vegetal pole of the embryo by unequal cleavage in the vegetal tier of four cells. Primary mesenchyme, the cleavage products of the micromeres, migrate into the blastocoel of the embryo where they interact with the extracellular matrix (ECM) and differentiate to produce the embryonic skeleton or spicule. Evidence from in vitro and in vivo studies suggests that the micromeres require a permissive environment or signal to initiate differentiation. An intact embryonic ECM is a major component of the permissive environment. The PI has recently shown that micromeres will differentiate in vitro if cultured on a reconstituted basal lamina (matrigel). Isolated micromeres cultured in sea water alone will not differentiate. What is the molecule in the matrigel which initiates differentiation and how is it related to the endogenous signalling molecule in the embryo. The PI proposes to: (1) identify and purify the spicule inducing activity (SIA) from the matrigel, (2) characterize the general mechanism of action of SIA, and (3) identify and initiate characterization of the homologous SIA activity from the sea urchin embryo.