B61 FUNCTION DURING VASCULAR DEVELOPMENT

描述(改编自《调查者摘要》)：逐渐成长 肿瘤依赖于新血管形成的持续刺激。 大量证据表明，受体-蛋白酪氨酸激酶 (r-PTKs)及其配体在细胞分化中起着至关重要的作用 内皮细胞及其随后进入血管的组织 系统。携带内皮细胞特异性突变的“基因敲除小鼠” R-PTK及其配体，如Flk-1、Flk-1、Tie-2和VEGF，导致 血管发育异常导致胚胎死亡。有趣的是， 每个基因的突变都会导致不同的表型异常。 这些数据表明，多条信号通路，每条都有 不重叠的功能，是阐述心内膜所必需的 和血管系统。重要的是要确定和描述其他 有助于内皮细胞发育的基因座，以定义 血管生成和血管生成需要多种途径。B61年， Eck R-PTK的主要配体(B61也结合Eph的其他成员 家族)，其他人表明拥有血管生成细胞和内皮细胞 引诱剂活性。与这一概念一致，B61表示为 小鼠胚胎发育过程中血管形成的部位。这些数据 提出一种耐人寻味的可能性，即B61在招聘过程中发挥着重要作用 内皮细胞进入发育中的血管系统。为了检验这一假设， 首先，B61配体的候选受体将通过以下方式确定 在发育过程中筛选Eph家族的每个成员的表达 对小鼠血管系统进行整体免疫组织化学染色。第二，基因 在胚胎干细胞中的靶向将被用来产生携带 B61基因座零突变。纯合子突变胚胎将被分析 针对内皮细胞和血管发育方面的缺陷。其影响范围 突变胚胎的血管发育将通过组织学进行评估 分析和检测Flk-1、Flt-1三个基因的表达 和Tek，这是内皮细胞早期和晚期的标志 差异化。第三，评估B61和EKE在肿瘤中的作用 血管生成，胚胎干细胞系在 B61和/或ECK基因座(即，B61-1和/或ECK-1细胞系)将用于 在同基因或免疫受损的小鼠身上产生畸胎癌。肿瘤 将在四周后检查肿瘤生长和血管的范围 发展。预计这些数据将提供对 B61/Eck信号通路在血管发育中的作用 胚胎发生和肿瘤发生。

DESCRIPTION (Adapted from Investigator's Abstract): Progressive growth of tumors is dependent on continuous stimulation of new blood vessel formation. Considerable evidence indicates that receptor-protein tyrosine kinases (R-PTKs) and their ligands have crucial roles in the differentiation of endothelial cells and their subsequent organization into the vascular system. "Knockout mice" carrying mutations in endothelial cell specific R-PTKs and ligands, such as flk-1, flk-1, tie-2, and VEGF, result in embryonic lethality due to aberrant vascular development. Interestingly, mutation in each gene gives rise to distinct phenotypic abnormalities. These data indicate that multiple signaling pathways, each with nonoverlapping functions, are required for elaboration of the endocardium and vasculature. It will be essential to identify and characterize other loci that contribute to endothelial cell development in order to define the multiple pathways required for vasculogenesis and angiogenesis. B61, the major ligand for the ECK R-PTK (B61 also binds other members of the eph family), was shown by others to possess angiogenic and endothelial cell attractant activity. Consistent with this notion, B61 is expressed at sites of blood vessel formation during mouse embryogenesis. These data raise the intriguing possibility that B61 has a major role in recruiting endothelial cells into the developing vasculature. To test this hypothesis, first, candidate receptors for the B61 ligand will be identified by screening each member of the eph family for expression in the developing mouse vascular system by whole mount immunohistochemistry. Second, gene targeting in embryonic stem cells will be used to generate mice that carry null mutations at the B61 locus. Homozygous mutant embryos will be analyzed for defects in endothelial cell and blood vessel development. The extent of vascular development in mutant embryos will be assessed by histological analysis and by examination of the expression of three genes, flk-1, flt-1 and tek , that are markers for early to late stages of endothelial cell differentiation. Third, to assess the role of B61 and eck in tumor angiogenesis, embryonic stem cell lines that carry double knockouts at the B61 and/or eck loci (i.e., B61-1- and/or eck-1 cell lines) will be used to generate teratocarcinomas in syngeneic or immunocompromised mice. Tumors will be examined after four weeks for extent of tumor growth and vascular development. It is anticipated that these data will provide insight into the function of the B61/ECK signaling pathway in vascular development during embryogenesis and tumorigenesis.