Regulation of tyrosine kinase signaling through interaction with membrane lipids

 描述（由申请人提供）：蛋白酪氨酸激酶6（PTK 6）是一种细胞内酪氨酸激酶，含有SH 3和SH 2结构域，但缺乏促进膜定位的SH 4结构域。缺乏膜靶向有助于其细胞内定位和接近底物的灵活性。在分化的前列腺上皮细胞中，PTK 6主要存在于细胞核中。然而，活性PTK 6与前列腺癌中的质膜相关，并且其表达增加与转移和较差的存活相关。我们发现，膜相关的PTK 6促进细胞转化，上皮间质转化和肿瘤细胞转移，而核PTK 6抑制生长。我们设计了一个合作提案来解决这个问题，“PTK 6是如何被招募到质膜上的，在那里它促进了肿瘤的发生？“我们的初步数据表明，PTK 6直接结合富含磷酸盐的脂质，包括血浆中的磷脂酰肌醇-（3，4，5）-三磷酸（PIP 3）。 膜的由于PI 3 K的活化和/或肿瘤抑制剂脂质磷酸酶PTEN的突变，在癌症中通常观察到PIP 3的产生增加。我们假设富含磷酸盐的脂质，如PIP 3调节质膜上PTK 6的募集和激活，以驱动肿瘤发生和转移。由细胞生物学家泰纳博士和结构生物化学家Gaponenko博士提出的高度协同研究使用一系列生物化学、生物物理学、分子学、遗传学和细胞生物学方法来：（i）研究PTK 6脂质结合;（ii）鉴定PTK 6中脂质结合所需的结构域;（iii）确定PI 3 K/PTEN/PIP 3对前列腺癌细胞膜上PTK 6活化的贡献;（iv）确定PI 3 K/PTEN/PIP 3对前列腺癌细胞膜上PTK 6活化的贡献。和（iv）在前列腺特异性缺失编码肿瘤抑制基因PTEN的小鼠中，检测PTK 6膜结合对前列腺肿瘤发生的贡献。这项研究的结果将定义细胞内酪氨酸激酶膜靶向和激活的新机制，并可能确定抑制癌症中PTK 6的新策略。此外，PTK 6细胞内定位或表达的改变可能为前列腺癌分期提供独特的标志物。

 DESCRIPTION (provided by applicant): Protein tyrosine kinase 6 (PTK6) is an intracellular tyrosine kinase that contains SH3 and SH2 domains, but lacks an SH4 domain that promotes membrane localization. Lack of membrane targeting facilitates flexibility in its intracellular localization and access to substrates. In differentiated prostate epithelial cells, PTK6 is primariy found in the nucleus. However, active PTK6 associates with the plasma membrane in prostate cancer, and its increased expression is correlated with metastasis and poor survival. We found that membrane-associated PTK6 promotes cell transformation, the epithelial mesenchymal transition, and tumor cell metastasis, while nuclear PTK6 inhibits growth. We designed a collaborative proposal to address the question, "How is PTK6 recruited to the plasma membrane where it promotes tumorigenesis?" Our preliminary data suggest PTK6 directly binds phosphate-rich lipids, including phosphatidylinositol-(3, 4, 5)-trisphosphate (PIP3), at the plasma membrane. Increased production of PIP3 is commonly observed in cancer due to activation of PI3K and/or mutation of the tumor suppressor lipid phosphatase PTEN. We hypothesize that phosphate-rich lipids, such as PIP3 regulate the recruitment and activation of PTK6 at the plasma membrane to drive tumorigenesis and metastases. Highly synergistic studies proposed by Dr. Tyner, a cell biologist, and Dr. Gaponenko, a structural biochemist, use an array of biochemical, biophysical, molecular, genetic and cell biology approaches to: (i) Investigate PTK6 lipid binding; (ii) Identify domains in PTK6 required for lipid binding; (iii) Determine contributions of PI3K/PTEN/PIP3 to activation of PTK6 at the membrane in prostate cancer cells; and (iv) Examine contributions of PTK6 membrane binding to prostate tumorigenesis in mice with prostate specific deletion of the gene encoding the tumor suppressor PTEN. The results of this research will define a novel mechanism for intracellular tyrosine kinase membrane targeting and activation, and could identify novel strategies to inhibit PTK6 in cancer. In additio, alterations in PTK6 intracellular localization or expression may provide a unique marker for staging prostate cancers.