The Btk29A Tyrosine Kinase Gene of Drosophila

Btk 29 A激酶是包括哺乳动物激酶Btk、Itk和Tec的酪氨酸激酶亚家族中唯一的果蝇成员。哺乳动物蛋白质是造血和免疫应答所需的，并且响应于来自B细胞和T细胞受体的信号传导而被激活。尽管Btk 29 A以动态和复杂的模式表达，包括血细胞，但对果蝇中Btk 29 A的需求几乎没有调查。PI最近鉴定了Btk 29 A突变体，并且能够表明它对于胚胎发生、眼睛中刚毛的形成以及卵子发生的后期阶段是必需的。此外，PI已显示Btk 29 A和Src 64 B之间的遗传相互作用，其编码与激活Btk、Itk和Tec的那些酪氨酸激酶密切相关的Src家族酪氨酸激酶。PI现在计划更密切地研究这种相互作用，并在Btk 29 A途径中寻找其他基因。为了更全面地了解Btk 29 A在胚胎发生、眼发育和卵子发生中的作用，PI将分离Btk 29 A无效突变体并构建拯救突变体表型的Btk 29 A转座子。 Btk 29 A和Src 64 B都是发育中的卵室中环道生长所需的，并且在遗传上相互作用以产生更极端的表型。PI将检测这些突变体对磷酸酪氨酸掺入环道的影响，并检测两种激酶是否直接相互作用。PI最近表明，环管进行磷酸苏氨酸以及磷酸酪氨酸和磷酸苏氨酸也依赖于Btk 29 A。PI计划检测磷酸酪氨酸信号是否通过小GTP酶的Ras或Rho家族转导为磷酸苏氨酸。 Btk 29 A和Src 64 B也是滤泡细胞背腹侧图案形成所必需的。PI计划测试它们是否在这些细胞中的Egfr-Ras通路中起作用。 在没有Btk 29 A的情况下，眼睛的间房刚毛被截断。PI计划使用标记的鬼笔环肽和Btk 29 A、磷酸酪氨酸和磷酸苏氨酸的抗体比较正常和突变刚毛的生长。然后PI将使用敏化筛选来分离增强或抑制刚毛表型的突变。在这些研究中，PI希望在Btk 29 A信号通路的新成员中发现突变。

The Btk29A kinase is the only Drosophila member of a subfamily of tyrosine kinases that includes the mammalian kinases Btk, Itk and Tec. The mammalian proteins are required for hematopoiesis and the immune response, and are activated in response to signaling from the B-cell and T-cell receptors. Although Btk29A is expressed in a dynamic and complex pattern that includes the blood cells, there has been little investigation of the requirements for Btk29A in Drosophila. The PI recently identified Btk29A mutants and was able to show that it is essential for embryogenesis, for formation of bristles in the eye, and for the late stages of oogenesis. In addition, the PI has shown a genetic interaction between Btk29A and Src64B, which encodes a Src-family tyrosine kinase closely related to those that activate Btk, Itk and Tec. The PI now plans to examine this interaction more closely and search for additional genes in the Btk29A pathway. To get a more complete idea of the roles of Btk29A in embryogenesis, eye development, and oogenesis, the PI will isolate Btk29A null mutants and construct a Btk29A transposon that rescues the mutant phenotypes. Both Btk29A and Src64B are required for ring canal growth in developing egg chambers and interact genetically to give a more extreme phenotype. The PI will test the effects of these mutants on phosphotyrosine incorporation into the ring canals and will test whether the two kinases interact directly. The PI has recently shown that ring canals carry phosphothreonine as well as phosphotyrosine and that the phosphothreonine is also dependent on Btk29A. The PI plans to test whether the phosphotyrosine signal is transduced to phosphothreonine via the Ras or Rho families of small GTPases. Btk29A and Src64B are also required for dorsoventral patterning of the follicle cells. The PI plans to test whether they work in the Egfr-Ras pathway in these cells. In the absence of Btk29A the interommatidial bristles of the eye are truncated. The PI plans to compare growth of normal and mutant bristles using labeled phalloidin and antibodies to Btk29A, phosphotyrosine and phosphothreonine. Then the PI will use a sensitized screen to isolate mutations that enhance or suppress the bristle phenotype. Among these the PI hopes to find mutations in new members of Btk29A signaling pathways.