Elucidating the role of palladin/alpha-actinin in cell motility and invasion

描述（由申请人提供）：癌症的特征是细胞具有侵袭性、侵袭性和经常转移性。只有一小部分肿瘤细胞具有转移的能力，而正是这一小部分转移细胞使癌症成为一种致命的疾病。因此，了解这种细胞群与正常肿瘤细胞的区别是至关重要的。如果我们能找到转移细胞特有的标记，那么我们就有希望杀死它们，或者至少限制它们。这一建议将集中于钯蛋白和a-肌动蛋白的精确分子功能，这两种蛋白都被认为在细胞运动特别是癌症转移中起着关键作用。新型蛋白palladin是一种多结构域的肌动蛋白相关蛋白，在脊椎动物物种中高度保守。palladin敲除小鼠显示出胚胎致死性表型，证实了palladin在哺乳动物胚胎发生中起着重要作用，并且palladin缺失的细胞在运动性和粘附性方面都存在缺陷。a-肌动蛋白还参与肌动蛋白交联，并作为多组分复合物的组装平台，参与细胞信号传导和肌动蛋白重组。最近，人类帕拉丁蛋白的突变（P239S突变）与一种遗传性胰腺癌有关，这表明帕拉丁蛋白功能受损可能导致一种高度侵袭性的人类疾病。这种突变也发生在与a-肌动蛋白结合所需的钯蛋白区域。因此，钯素和a-肌动蛋白在功能和物理上都与正常和病理细胞运动有关。目前的研究主要集中在使用钯或a-肌动蛋白水平作为预后的生物标志物。然而，我们的假设是钯素/a-肌动蛋白复合物是转移性癌症的相关生物标志物，并希望这项工作将导致改善最致命癌症的预后标志物。目前，这个复合体在组织肌动蛋白细胞骨架中的确切分子作用尚不清楚。我们建议利用核磁共振来解决溶液中配合物的结构，从而指导我们对钯的合理诱变以破坏配合物。然后，我们将使用转染培养的乳腺癌细胞来表征钯蛋白突变体的生物活性，这些突变体缺乏结合a-actin的能力。总之，这些目标将使我们能够确定帕拉丁蛋白和a-肌动蛋白之间相互作用在细胞运动和侵袭中的生物学意义。

DESCRIPTION (provided by applicant): Cancer is characterized by cells that are aggressive, invasive, and often metastatic. Only a subset of tumor cells possesses the ability to metastasize, and yet it is the metastatic sub-population that makes cancer a lethal disease. Therefore, it is critical to understand how this population of cells differs from normal tumor cells. If we can find markers that are specific to the metastatic cells, then there is a hope that we can kill them, or at least restrict them. This proposal will focus on the precise molecular function of palladin and a-actinin, two proteins that have both been implicated as playing critical roles in cell motility and particularly in cancer metastasis. The novel protein palladin is a multi-domain, actin-associated protein that is highly conserved among vertebrate species. The palladin knockout mouse displays a phenotype of embryonic lethality, confirming that palladin plays an essential role in mammalian embryogenesis, and palladin null cells have defects in both motility and adhesion. a-Actinin is also involved in actin-crosslinking and serves as a platform for the assembly of multi-component complexes involved in cell signaling and actin reorganization. Recently, a mutation in human palladin (the P239S mutation) was implicated in an inherited form of pancreatic cancer, suggesting that impaired palladin function may contribute to a highly invasive human disease. This mutation also occurs in a region of palladin required for binding to a-actinin. Therefore palladin and a-actinin are both functionally and physically linked to both normal and pathological cell motility. Current research is focused on using palladin or a-actinin levels as prognostic biomarkers. Yet, our hypothesis is that the palladin/a-actinin complex is the relevant biomarker for metastatic cancer and hope that this work will lead to improved prognostic markers for the deadliest of cancers. Currently the precise molecular role of this complex in organizing the actin cytoskeleton is unknown. We propose to solve the structure of the complex in solution using nuclear magnetic resonance, which will in turn guide our rational mutagenesis of palladin to disrupt the complex. Then we will use transfection of cultured breast cancer cells to characterize the biological activity of palladin mutants that are deficient in their ability to bind a-actinin. Together, these aims will allow us to determine the biological significance of the interaction between palladin and a-actinin in cell motility and invasion.