Comparative analysis of osr1 function in nephrogenesis

描述（由申请人提供）：odd -skip related 1 （osr1）是已知最早在中间中胚层（IM）形成过程中表达的基因，中间中胚层是所有脊椎动物肾脏组织的胚胎组织。在斑马鱼、鸡和小鼠胚胎中，osr1在未分化的IM中表达，并在肾管和小管形成开始时下调。将morpholinos注射到斑马鱼的osr1中，导致早期肾脏标记几乎完全丢失，背部和腹部标记都扩大，并且出现类似于Bmp2b突变漩涡的超收敛扩展表型。osr1纯合缺失的小鼠在肾脏形成方面有严重缺陷。鸡胚中osr1的错误表达会导致体细胞中肾基因的异位表达。最后，osr1的表达在斑马鱼漩涡突变体中缺失。根据这些数据，可以提出关于肾形成过程中osr1的功能和调控的几种不相互排斥的假设：(1)osr1在早期胚胎模式中起作用，抑制背侧和腹侧模式，并建立一个能形成IM的组织带；(2) osr1直接促进早期肾脏基因表达；(3) osr1维持肾前体细胞在早期谱系室中并抑制上皮结构的终末分化。这些假设将通过在斑马鱼、鸡和小鼠胚胎中进行osr1功能的获得和丧失实验，通过研究其他肾脏调节基因错误表达对osr1表达的影响，以及通过检查斑马鱼背-腹模式突变体中osr1的表达来验证。通过对三种不同脊椎动物胚胎中osr1的研究，我们可以更全面地了解osr1在肾脏形成过程中的作用，这将有助于我们对肾脏发育调控的理解。这些研究也可能会增加对先天性肾脏异常的了解，并可能产生重要的信息，可用于产生用于治疗目的的肾脏组织。

DESCRIPTION (provided by applicant): Odd-skipped related 1 (osr1) is the earliest gene known to be expressed during the formation of the intermediate mesoderm (IM), the embryonic tissue which gives rise to all vertebrate kidney tissue. In zebrafish, chicken, and mouse embryos, osr1 is expressed in undifferentiated IM, and is down regulated upon initiation of kidney duct and tubule formation. Injection of morpholinos to osr1 in zebrafish leads to almost complete loss of early kidney markers, expansion of both dorsal and ventral markers, and a hyperconvergent extension phenotype similar to the Bmp2b mutant swirl. Mice with homozygous deletions in osr1 have severe defects in kidney formation. Misexpression of osr1 in chicken embryos results in ectopic expression of kidney genes in the somite. Finally, osr1 expression is lost in zebrafish swirl mutants. From these data, several, not mutually exclusive hypotheses regarding the function and regulation of osr1 during kidney formation can be postulated: (1) osr1 functions during early embryonic patterning to inhibit dorsal and ventral patterning and establish a band of tissue competent to form IM; (2) osr1 directly promotes early kidney gene expression; and (3) osr1 maintains kidney precursor cells in an early lineage compartment and inhibits terminal differentiation of epithelial structures. These hypothesis will be tested by conducting osr1 gain and loss of function experiments in zebrafish, chicken, and mouse embryos, by studying the effects of the misexpression of other kidney regulatory genes on osr1 expression, and by examining osr1 expression in zebrafish dorso-ventral patterning mutants. By studying osr1 in three diverse vertebrate embryos, a comprehensive picture should emerge of the roles of osr1 during kidney formation, which should add significantly to our understanding of the regulation of kidney development. The studies may also lead to increased understanding of congenital kidney anomalies and may yield important information that can be used to generate kidney tissue for therapeutic purposes.