Genetic Analysis of Cell Invasion through Basement Membranes

描述(申请人提供)：我们的长期目标是阐明通过基底膜引导细胞入侵的遗传网络，基底膜是包围大多数组织的致密、片状的细胞外基质。细胞在体内穿过基底膜的机制仍然知之甚少，因为这些入侵通常发生在复杂的环境中，很难研究。因此，我们正在解剖锚细胞(AC)侵入外阴上皮的过程，这是一种视觉上和遗传上可获得的模式生物--秀丽线虫。AC侵袭包括：(1)AC与基底膜的结合，(2)AC向基底膜的极化，(3)刺激侵袭的趋化信号(S)的产生和接收，(4)基底膜的精确去除和(5)基底膜的转运。我们发现了Netrin通路在引导AC侵袭性细胞过程的极化向基底膜方向的一个新的作用。我们还鉴定了线虫FOS转录因子的一个特殊亚型，FOS-1b，它可能通过阻断FOS-1a的活性来抑制AC的入侵，FOS-1a是一种促进AC入侵过程中基底膜清除的亚型。最后，我们使用从以前的全基因组RNAi筛选产生的数据库进行了中试筛选，并鉴定了另外五个促进AC侵袭的基因，其中四个以前没有涉及到调节细胞侵袭。结合细胞、遗传和分子方法，我们提出的工作将：1)阐明Netrin信号在极化侵袭细胞中的新作用，2)确定FOS-1b抑制AC侵袭的机制，以及3)在我们的RNAi数据库筛选中发现的新基因的功能，这些基因特异性地促进AC侵袭过程中基底膜的去除。细胞通过基底膜的侵入在正常发育过程中起着至关重要的作用，对于白细胞向感染和损伤部位的运输是必不可少的。不受控制的细胞侵袭活动也与许多致命疾病有关，包括癌症和类风湿性关节炎。这项拟议的工作将促进我们对控制细胞侵袭行为的基本机制的理解，因此有很大潜力为一些与不受控制的细胞侵袭活动相关的人类疾病带来新的治疗策略。

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.