The Btk29A Tyrosine Kinase Gene of Drosophila

Btk29A激酶是酪氨酸激酶亚家族中唯一的果蝇成员，该亚家族包括哺乳动物激酶Btk， Itk和Tec。这些哺乳动物蛋白是造血和免疫反应所必需的，并在响应b细胞和t细胞受体的信号时被激活。尽管Btk29A以包括血细胞在内的动态和复杂的模式表达，但果蝇对Btk29A的需求的研究很少。PI最近发现了Btk29A突变体，并能够证明它对胚胎发生、眼睛刚毛的形成和卵子发生的后期阶段至关重要。此外，PI显示Btk29A和Src64B之间存在遗传互作，Src64B编码的src家族酪氨酸激酶与激活Btk， Itk和Tec的激酶密切相关。PI现在计划更密切地研究这种相互作用，并在Btk29A途径中寻找其他基因。为了更全面地了解Btk29A在胚胎发生、眼睛发育和卵子发生中的作用，PI将分离Btk29A零突变体，并构建一个拯救突变表型的Btk29A转座子。Btk29A和Src64B都是发育中的卵室环管生长所必需的，并在遗传上相互作用，产生更极端的表型。PI将测试这些突变体对磷酸酪氨酸进入环管的影响，并将测试这两种激酶是否直接相互作用。PI最近表明，环管携带磷酸苏氨酸和磷酸酪氨酸，磷酸苏氨酸也依赖于Btk29A。PI计划测试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。Btk29A和Src64B也是卵泡细胞的背腹图案所必需的。PI计划测试它们是否在这些细胞的Egfr-Ras通路中起作用。在缺少Btk29A的情况下，眼间刚毛被截断。PI计划使用标记的phalloidin和Btk29A、磷酸酪氨酸和磷酸苏氨酸抗体来比较正常和突变猪鬃的生长情况。然后PI将使用敏化筛选来分离增强或抑制猪鬃表型的突变。其中，PI希望在Btk29A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.