Genetic Analysis of Cell Invasion through Basement Membranes

描述（由申请人提供）：我们的长期目标是阐明通过基底膜（包围大多数组织的致密片状细胞外基质）指导细胞入侵的遗传网络。细胞在体内穿越基底膜的机制仍然知之甚少，因为这些入侵通常发生在难以研究的复杂环境中。因此，我们剖析了锚定细胞（AC）在视觉和遗传上可接近的模式生物秀丽隐杆线虫中侵入外阴上皮的过程。交流电的侵袭包括：(1)交流电附着在基膜上，(2)交流电向基膜极化，(3)产生和接收刺激侵袭的趋化信号，(4)精确去除基膜，(5)通过基膜。我们发现了网状蛋白通路在指导AC侵袭细胞过程向基底膜极化中的新作用。我们还鉴定了秀丽隐杆线虫fos转录因子fos-1b的一个特异性异构体，fos-1b可能通过阻断fos-1a活性来抑制AC入侵，而fos-1a是一个在AC入侵过程中促进基底膜去除的异构体。最后，我们利用先前全基因组RNAi筛选产生的数据库进行了试点筛选，并确定了另外五个促进AC入侵的基因，其中四个先前未涉及调节细胞入侵。结合细胞、遗传和分子方法，我们提出的工作将：1)阐明netrin信号在侵袭细胞极化中的新作用，2)确定fos-1b抑制AC侵袭的机制，以及3)表征在我们的RNAi数据库筛选中发现的新基因的功能，这些基因在AC侵袭过程中专门促进基底膜的去除。通过基底膜的细胞入侵在正常发育过程中起着至关重要的作用，并且是白细胞运输到感染和损伤部位的必要条件。不受控制的细胞侵袭活动也与许多致命疾病有关，包括癌症和类风湿关节炎。这项工作将促进我们对控制细胞侵袭行为的基本机制的理解，因此具有很强的潜力，可以为许多与不受调节的细胞侵袭活动相关的人类疾病提供新的治疗策略。

DESCRIPTION (provided by applicant): Our long-term goal is to elucidate the genetic networks that direct cell invasion through basement membranes, the dense, sheet-like extracellular matrix that surrounds most tissues. The mechanisms that cells employ to cross basement membranes in vivo remain poorly understood, as these invasions most often occur in complex environments that are difficult to study. We are thus dissecting the process of anchor-cell (AC) invasion into the vulval epithelium in the visually and genetically accessible model organism Caenorhabiditis elegans. AC invasion involves: (1) the attachment of the AC to the basement membrane, (2) its polarization towards the basement membrane, (3) the generation and reception of a chemotactic signal(s) that stimulates invasion, (4) the precise removal of the basement membrane and (5) transit through the basement membrane. We have discovered a novel role for the netrin pathway in directing the polarization of the AC's invasive cellular processes towards the basement membrane. We have also identified a specific isoform of the C. elegans fos transcription factor, fos-1b, which inhibits AC invasion, perhaps by blocking fos-1a activity, an isoform that promotes basement membrane removal during AC invasion. Finally, we have conducted a pilot screen using a database generated from previous whole genome RNAi screens and identified five additional genes that promote AC invasion, four of which have not previously been implicated in regulating cell invasion. Integrating cellular, genetic, and molecular approaches, our proposed work will: 1) elucidate a new role for netrin signaling in polarizing an invasive cell, 2) determine the mechanisms by which fos-1b inhibits AC invasion, and 3) characterize the function of new genes identified in our RNAi database screen that specifically promote removal of the basement membrane during AC invasion. Cell invasions through basement membranes play crucial roles during normal development and are essential for leukocyte trafficking to sites of infection and injury. Uncontrolled cell- invasive activity is also associated with a number of deadly diseases, including cancer and rheumatoid arthritis. The proposed work will advance our understanding of the fundamental mechanisms controlling cell- invasive behavior and thus has a strong potential to lead to new treatment strategies for a number of human diseases associated with unregulated cell-invasive activity.