Comparative analysis of osr1 function in nephrogenesis

描述（由申请人提供）：Odd-skipped related 1（osr1）是已知在中间中胚层（IM）形成期间表达的最早基因，中间中胚层是产生所有脊椎动物肾组织的胚胎组织。在斑马鱼、鸡和小鼠胚胎中，osr1在未分化的IM中表达，并在肾导管和小管形成开始时下调。注射morpholinos斑马鱼osr1导致几乎完全丧失早期肾脏标记，扩大背侧和腹侧标记，和超收敛延伸表型类似的Bmp2b突变漩涡。osr1纯合缺失的小鼠在肾脏形成方面有严重缺陷。osr1在鸡胚中的错误表达导致肾基因在体节中的异位表达。最后，osr1表达在斑马鱼漩涡突变体中丢失。从这些数据中，可以提出几个关于osr 1在肾脏形成过程中的功能和调节的不相互排斥的假设：（1）osr 1在早期胚胎图案形成过程中起作用，以抑制背侧和腹侧图案形成，并建立一条能够形成IM的组织带;（2）osr 1直接促进早期肾脏基因表达;和（3）OSR 1维持早期谱系区室中的肾前体细胞并抑制上皮结构的终末分化。这些假设将进行osr1增益和损失的功能实验在斑马鱼，鸡，小鼠胚胎，通过研究其他肾脏调控基因的错误表达对osr1表达的影响，并通过检查osr1在斑马鱼背腹图案突变体的表达进行测试。通过研究osr1在三种不同脊椎动物胚胎中的表达，我们可以全面了解osr1在肾脏形成过程中的作用，这将大大增加我们对肾脏发育调控的理解。这些研究还可能导致增加对先天性肾脏异常的理解，并可能产生可用于产生用于治疗目的的肾脏组织的重要信息。

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.