Supervillin modulation of focal adhesions involving TRIP6/ZRP-1

Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
The Journal of Cell Biology (Impact Factor: 9.83). 08/2006; 174(3):447-58. DOI: 10.1083/jcb.200512051
Source: PubMed


Cell-substrate contacts, called focal adhesions (FAs), are dynamic in rapidly moving cells. We show that supervillin (SV)--a peripheral membrane protein that binds myosin II and F-actin in such cells--negatively regulates stress fibers, FAs, and cell-substrate adhesion. The major FA regulatory sequence within SV (SV342-571) binds to the LIM domains of two proteins in the zyxin family, thyroid receptor-interacting protein 6 (TRIP6) and lipoma-preferred partner (LPP), but not to zyxin itself. SV and TRIP6 colocalize within large FAs, where TRIP6 may help recruit SV. RNAi-mediated decreases in either protein increase cell adhesion to fibronectin. TRIP6 partially rescues SV effects on stress fibers and FAs, apparently by mislocating SV away from FAs. Thus, SV interactions with TRIP6 at FAs promote loss of FA structure and function. SV and TRIP6 binding partners suggest several specific mechanisms through which the SV-TRIP6 interaction may regulate FA maturation and/or disassembly.

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    • "To study the role of TRIP6 in the nervous system, we asked whether it was present in the brains of embryonic and adult mice. For this, we first examined the specificity of the TRIP6 antibody, which has been reported to be able to detect endogenous TRIP6 by immunobloting (Xu et al., 2004) and immunostaining (Takizawa et al., 2006). In 3T3 cells, this antibody detected endogenous TRIP6 at focal adhesions in the scrambled shRNA-expressing cell, but not in the cell expressing shTRIP6 (Fig. 1A). "
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    ABSTRACT: Background: Postnatal neurogenesis persists throughout life in the subventricular zone (SVZ)-olfactory bulb pathway in mammals. Extrinsic or intrinsic factors have been revealed to regulate neural stem cell (NSC) properties and neurogenesis. Thyroid hormone receptor interacting protein 6 (TRIP6) belongs to zyxin family of LIM proteins, which have been shown to interact with various proteins to mediate cellular functions. However, the role of TRIP6 in NSCs is still unknown. Results: By performing double immunofluorescence staining, we found that TRIP6 was expressed by Sox2-positive NSCs in embryonic and postnatal mouse forebrains. To study the function of TRIP6 in NSCs, we performed overexpression and knockdown experiments with neurospheres derived from postnatal day 7 SVZ. We found that TRIP6 was necessary and sufficient for self-renewal and proliferation of NSCs, but inhibited their differentiation. To further investigate the mechanism of TRIP6 in NSCs, we performed Luciferase reporter assay and found that TRIP6 activated Notch signaling, a pathway required for NSC self-renewal. Conclusions: Our data suggest that TRIP6 regulates NSC maintenance and it may be a new marker for NSCs.
    Preview · Article · Sep 2014 · Developmental Dynamics
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    • "TRIP6, another member of the zyxin family LIM domain proteins, (Yi and Beckerle, 1998; Lin and Lin, 2011) can also be targeted to focal adhesions. TRIP6 binding partners include supervillin and lysophosphatidic acid (LPA) 2 receptor (Xu et al., 2004; Takizawa et al., 2006), and has been suggested to facilitate focal adhesion turnover in epithelial cells and to mediate LPA-induced cell migration (Xu et al., 2004; Takizawa et al., 2006). Similar to zyxin, RNAi mediated knock-down of TRIP6-induced increased cell adhesion to FN in a fibroblast-like cell line COS7 (Takizawa et al., 2006), implicating that TRIP6 may not contribute to the increased VSMC adhesion. "
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    ABSTRACT: Zyxin is a focal adhesion protein that has been implicated in the modulation of cell adhesion and motility, and is hypothesized to be a mechano-sensor in integrin-mediated responses to mechanical force. To test the functional role of zyxin in the mechanotransduction of microvascular smooth muscle cells (VSMC), we utilized atomic force microscopy (AFM) to apply localized pulling forces to VSMC through a fibronectin (FN) focal adhesion induced by a FN-coated bead on cell surface. Application of force with the AFM induced an increase of zyxin accumulation at the site of the FN-bead focal adhesion that accompanied the VSMC contractile response. Whereas, reduction of zyxin expression by using a zyxin-shRNA construct abolished the VSMC contractile response to AFM pulling forces, even though the zyxin-silenced VSMCs displayed increased adhesion to FN in both AFM adhesion assays and cell adhesion assays. The reduced zyxin expression significantly impaired cell spreading and reorganization of the actin cytoskeleton that could indicate a possible underlying reason for the loss of a contractile response to mechanical force. Consistent with these observations, in zyxin-silenced VSMC, we also observed a reduced expression of Rac1, which plays an important role in the actin reorganization in VSMC, but increased thyroid receptor-interacting proteins (TRIP6) and FAK expression, the latter being a major protein that promote cell adhesion. In conclusion, these data support an important enabling role for zyxin in VSMCs ability to mechanically respond to applied force.
    Full-text · Article · Dec 2012 · Frontiers in Physiology
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    • "Nevertheless, the current level of resolution is consistent with a model in which myosin II and actin may induce localized folding as they interact with the supervillin N-terminus at or near the ligand-binding sites predicted by ANCHOR. As noted above, the focal adhesion-targeting sequence of supervillin (Takizawa et al., 2006) is also associated with a region containing predicted disordered ligand-binding sites. "
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    ABSTRACT: Supervillin, the largest member of the villin/gelsolin family, is a cytoskeleton regulating, peripheral membrane protein. Supervillin increases cell motility and promotes invasive activity in tumors. Major cytoskeletal interactors, including filamentous actin and myosin II, bind within the unique supervillin amino terminus, amino acids 1-830. The structural features of this key region of the supervillin polypeptide are unknown. Here, we utilize circular dichroism and bioinformatics sequence analysis to demonstrate that the N-terminal part of supervillin forms an extended intrinsically disordered region (IDR). Our combined data indicate that the N-terminus of human and bovine supervillin sequences (positions 1-830) represents an IDR, which is the largest IDR known to date in the villin/gelsolin family. Moreover, this result suggests a potentially novel mechanism of regulation of myosin II and F-actin via the intrinsically disordered N-terminal region of hub protein supervillin.
    Full-text · Article · Oct 2012 · Journal of biomolecular Structure & Dynamics
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