Directing the Fate of Cells to Myogenic Lineages

基于细胞的再生医学是发育生物学的自然延伸。胚胎干 胚胎干细胞（ES细胞）产生整个胚胎，并具有修复疾病组织的潜力。 成年人细胞分化之前的规范，一个过程，限制这些多能 一个特定的细胞系。组织再生取决于某些因子的可用性， 将干细胞指定为所需谱系并促进其分化。鉴于 患病组织的环境不太可能与发育中的胚胎、茎 细胞在植入之前或植入期间可能需要“调节”。总体假设指导 建议的研究是：（1）多能干细胞的命运可以在体外和体内通过 干细胞以前致力于一个特定的谱系，和（2）诱导过程是介导的 可溶性因子和细胞-细胞粘附的组合。该项目建立在我们发布的 在体内表达MyoD mRNA的鸡上胚层细胞募集多能上胚层的观察 通过释放一种抑制骨骼肌分化的因子， 形态发生蛋白（BMP）信号通路，促进N-钙粘蛋白的表达。在 缺乏MyoD阳性上胚层细胞，更多的多能细胞形成心肌。中的关键事件 肌肉分化是E-钙粘蛋白的下调。初步研究表明， 上胚层中MyoD阳性细胞的消融导致通过腹侧的器官疝出 体壁和体节中骨骼肌的减少。拟议的研究旨在 探讨MyoD阳性上胚层细胞促进骨骼肌发生的机制。 体节，并确定调节钙粘蛋白转换和细胞募集的因素 骨骼肌和心肌细胞系的作用。实验将集中在Wnt的作用， 7 GF-/3、BMP和BMP抑制剂家族成员参与这些过程。拟议的研究可 揭示了一种调节体内骨骼肌发生的新机制，并导致了 调节干细胞以确保它们偏向于沿着沿着 并在植入前表达适当的细胞-细胞粘附蛋白 进入病变组织。

Cell-based regenerative medicine is a natural extension of developmental biology. Embryonic stem cells (ES cells) give rise to the entire embryo and have the potential to repair diseased tissues in the adult. Cell differentiation is preceded by specification, a process that restricts these pluripotent cells to a particular lineage. Tissue regeneration is dependent on the availability of factors that specify stem cells to the desired lineage and promote their differentiation. Given that the environment of diseased tissues is unlikely to be the same as that of the developing embryo, stem cells may require "conditioning" prior to or during implantation. The overall hypotheses guiding the proposed research are: (1) the fate of pluripotent stem cells can be directed in vitro and in vivo by stem cells previously committed to a particular lineage, and (2) the induction process is mediated by a combination of soluble factors and cell-cell adhesions. This project builds on our published observations that chick epiblast cells expressing MyoD mRNA in vivo recruit pluripotent epiblast cells to the skeletal muscle lineage in vitro by releasing a factor(s) that inhibits the bone morphogenetic protein (BMP) signaling pathway and promotes the expression of N-cadherin. In the absence of MyoD positive epiblast cells, more pluripotent cells form cardiac muscle. A key event in muscle differentiation is the downregulation of E-cadherin. Preliminary studies demonstrate that ablation of MyoD positive cells in the epiblast results in herniation of the organs through the ventral body wall and a reduction in skeletal muscle in the somites. The proposed studies are designed to explore the mechanism whereby MyoD positive epiblast cells promote skeletal myogenesis in the somites in vivo, and to identify the factors that regulate cadherin switching and recruitment of cells to the skeletal and cardiac muscle lineages in vitro. The experiments will focus on the roles of Wnt, 7GF-/3, BMP, and BMP inhibitor family members in these processes. The proposed studies may reveal a novel mechanism for regulating skeletal myogenesis in vivo, and lead to the development of methods for conditioning stem cells to ensure that they are biased to differentiate along the desired pathway and express the appropriate cell-cell adhesion proteins prior to their implantation into diseased tissues.