Molecular Basis of ILK/PINCH Function in Cell Adhesion

细胞与细胞外基质（ECM）的粘附对于多种生理和病理性疾病至关重要。 流程.这种相互作用（细胞粘附）主要由整合素介导，整合素是一组异二聚体的整合素。 跨膜受体通过其胞外结构域与ECM蛋白结合。在ECM接合时， 整合素聚集并将信号传递到细胞内区室，导致大蛋白质的形成 称为粘着斑（FA）的复合物，其将整联蛋白胞质尾（CT）连接到肌动蛋白细胞骨架。 这后一步骤，即，FA的形成及其与肌动蛋白的连接促进了牢固的细胞粘附。而且 允许调节动态粘附过程，例如细胞扩散和迁移。我们的长期目标是 获得详细的分子理解的脂肪酸，并阐明他们是如何连接到肌动蛋白， 在各种粘合过程中调制。为此，我们一直专注于 FAs -整联蛋白连接激酶（ILK）。最初被发现是一种与整合素结合的整合素连接蛋白。 CTs，ILK已被确定为一种多功能蛋白，其传递多种机械和生物化学信号， 整合素和肌动蛋白之间的信号。ILK功能的关键初始步骤是其与PINCH -一种LIM-的紧密结合。 包含适配器。这种相互作用不仅促进ILK定位于整合素粘附位点， 创建了一个稳定的平台，包含许多蛋白质来调节动态FA组装和多种信号传导 途径。在过去的几年里，我们在构建分子生物学方面取得了重大进展。 ILK/PINCH网络的景观，并展示了它如何在各种时空方式中发挥作用 细胞过程在与临床科学家的合作中，我们还表明ILK/PINCH复合物是 在衰竭的人类心脏中异常升高，表明其直接参与心脏功能障碍。 巧合的是，最近的一项小鼠研究表明，G-肌动蛋白螯合肽胸腺素β 4（tb 4）可能 通过调节ILK/PINCH介导的细胞迁移和存活来修复心脏损伤。虽然这导致了 广泛的随访调查和启动基于tb 4的治疗心脏病的1A期临床试验 损伤患者，潜在的分子机制仍然不清楚。在初步调查中， 发现了一种新的ILK/PINCH介导的整合素-肌动蛋白连接，可能对细胞迁移至关重要， 生存这种联系似乎是由tb 4动态调节的。在下一阶段的研究中，我们将使用 多学科的结构/功能的方法，积极研究这种联系和它的调节TB 4。 这些研究将为理解ILK/PINCH介导的细胞粘附提供新的范式。他们将 也影响心脏病和可能的其它疾病的基于TB 4的治疗。

The attachment of cells to extracellular matrix (ECM) is crucial for a variety of physiological and pathological processes. This interaction (cell adhesion) is mediated primarily by integrins, a group of heterodimeric transmembrane receptors that bind to ECM proteins via their extracellular domains. Upon ECM engagement, integrins cluster and transduce signals into intracellular compartment leading to the formation of large protein complexes called focal adhesions (FAs) that connect integrin cytoplasmic tails (CTs) to the actin cytoskeleton. This latter step, i.e., the formation of FAs and their linkage to actin, promotes firm cell adhesion. Furthermore, it allows regulation of dynamic adhesive processes such as cell spreading and migration. Our long term goal is to obtain a detailed molecular understanding of FAs and to elucidate how they are connected to actin and modulated during various adhesive processes. To this end, we have been focusing on a major component of FAs - integrin-linked kinase (ILK). Originally discovered as an integrin linking protein that binds to integrin ¿ CTs, ILK has been established as a multifunctional protein that transmits diverse mechanical and biochemical signals between integrins and actin. A key initial step for ILK function is its tight binding to PINCH - a LIM- containing adaptor. This interaction not only promotes the localization of ILK to integrin adhesion sites but also creates a stable platform that harbors many proteins to regulate dynamic FA assembly and diverse signaling pathways. Over the past several years, we have made a major progress towards building a molecular landscape of the ILK/PINCH network and showed how it functions in a spatiotemporal manner in various cellular processes. In collaboration with clinical scientists, we have also shown that the ILK/PINCH complex is abnormally elevated in failing human hearts, suggesting its direct involvement in cardiac dysfunction. Coincidently, a recent study in mice has shown that a G-actin sequestering peptide, thymosin beta-4 (tb4), may repair cardiac damage by modulating the ILK/PINCH-mediated cell migration and survival. While this has led to widespread follow-up investigations and the launching of a tb4-based phase1A clinical trial on treating heart injury patients, the underlying molecular mechanism remains obscure. In preliminary investigation, we have discovered a novel ILK/PINCH-mediated integrin-actin linkage that may be crucial for cell migration and survival. This linkage appears to be dynamically regulated by tb4. In the next phase of our study, we will use multidisciplinary structural/functional approach to vigorously investigate this linkage and its regulation by tb4. The studies will lead to a new paradigm for understanding the ILK/PINCH-mediated cell adhesion. They will also impact on the tb4-based therapy of cardiac disorder and possibly other diseases.