Paxillin and Hic-5 Interaction with Vinculin Is Differentially Regulated by Rac1 and RhoA

Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, United States of America.
PLoS ONE (Impact Factor: 3.23). 05/2012; 7(5):e37990. DOI: 10.1371/journal.pone.0037990
Source: PubMed


Cell migration is of paramount importance to organism development and maintenance as well as multiple pathological processes, including cancer metastasis. The RhoGTPases Rac1 and RhoA are indispensable for cell migration as they regulate cell protrusion, cell-extracellular matrix (ECM) interactions and force transduction. However, the consequences of their activity at a molecular level within the cell remain undetermined. Using a combination of FRET, FRAP and biochemical analyses we show that the interactions between the focal adhesion proteins vinculin and paxillin, as well as the closely related family member Hic-5 are spatially and reciprocally regulated by the activity of Rac1 and RhoA. Vinculin in its active conformation interacts with either paxillin or Hic-5 in adhesions in response to Rac1 and RhoA activation respectively, while inactive vinculin interacts with paxillin in the membrane following Rac1 inhibition. Additionally, Rac1 specifically regulates the dynamics of paxillin as well as its binding partner and F-actin interacting protein actopaxin (α-parvin) in adhesions. Furthermore, FRET analysis of protein:protein interactions within cell adhesions formed in 3D matrices revealed that, in contrast to 2D systems vinculin interacts preferentially with Hic-5. This study provides new insight into the complexity of cell-ECM adhesions in both 2D and 3D matrices by providing the first description of RhoGTPase-coordinated protein:protein interactions in a cellular microenvironment. These data identify discrete roles for paxillin and Hic-5 in Rac1 and RhoA-dependent cell adhesion formation and maturation; processes essential for productive cell migration.

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    • "Hydogen peroxide inducible clone (HIC)-5 is a focal adhesion adapter protein that integrates the function and enzymatic activity of a variety of proteins at focal adhesion sites [Deakin et al., 2012]. Mechanical stress induces HIC-5 to relocalize from focal adhesions to actin stress fibers where it can regulate the contractility of cells [Kim-Kaneyama et al., 2005]. "
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    • "This subversion of mechanosensory pathways provides cancer cells with survival signals in unfavorable conditions. Accordingly , the alteration in expression of proteins such as integrins, FAK, CAS, paxillin (Deakin et al., 2012; Tikhmyanova et al., 2010; Zhao and Guan, 2009) or in the activity of ␤ 1 integrin (Indra and Beningo, 2011) are very common in metastatic cancer cell lines. Biomechanical signaling has recently been recognized as being crucial for proper embryogenesis and development. "
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    • "Vinculin is a 116-kDa cytoskeletal protein that is involved in the linkage of integrin adhesion molecules to the actin cytoskeleton [32]. Vinculin interacts with many proteins including talin [33], [34], [35], alpha-actinin [36], F-actin [37], [38], ARP2/3 [39], catenin [40], [41], [42], [43], Paxillin [44], Hic-5 [44], VASP [45] and vinexin [46], [47], [48]. Structurally, vinculin is divided into three main domains: an N-terminal head, a flexible proline-rich hinge (neck) region, and a C-terminal tail domain [49]. "
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