Lsc activity is controlled by oligomerization and regulates integrin adhesion

Hu, Jiancheng; Strauch, Pamela; Rubtsov, Anatoly V.; Donovan, Erin; Pelanda, Roberta; Torres, Raul M.

doi:10.1016/j.molimm.2007.11.002

Cited by 19 publications

(21 citation statements)

References 61 publications

(115 reference statements)

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“…RhoA participates in a number of cell biological processes including regulating cytoskeletal organization, integrin adhesion, and integrin signaling (13). We have previously shown that in B-lymphocytes, Arhgef1 is required for resolving integrin adhesion (14,15), and analyses of Arhgef1-deficient mouse mutants have further demonstrated a requirement for Arhgef1 in leukocyte migration and adhesion (14,16), consistent with the reported role for Arhgef1 in fibroblast adhesion to fibronectin (17).…”

Section: During An Inflammatory Response Resident and Newly Recruitesupporting

confidence: 68%

Thromboxane Receptor Signaling Is Required for Fibronectin-induced Matrix Metalloproteinase 9 Production by Human and Murine Macrophages and Is Attenuated by the Arhgef1 Molecule

Hartney

Gustafson

Bowler

et al. 2011

Journal of Biological Chemistry

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Section: During An Inflammatory Response Resident and Newly Recruitesupporting

confidence: 68%

Thromboxane Receptor Signaling Is Required for Fibronectin-induced Matrix Metalloproteinase 9 Production by Human and Murine Macrophages and Is Attenuated by the Arhgef1 Molecule

Hartney

Gustafson

Bowler

et al. 2011

Journal of Biological Chemistry

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“…In addition, we used an inducible homodimerization system to show that dimeric (541–605)PRG-FKBP induced actin bundling whereas monomeric (541–605)PRG-FKBP did not. Intriguingly, PRG, and the other RGS-RhoGEFs LARG and p115-RhoGEF, have been shown to exist as dimers, or possibly higher order oligomers, in cells (22, 23, 39, 40). Thus, we can speculate that PRG may affect the structure of the actin cytoskeleton in cells independent of or synergistic with its ability to activate Rho.…”

Section: Discussionmentioning

confidence: 99%

The Amino Acid Motif L/IIxxFE Defines a Novel Actin-Binding Sequence in PDZ-RhoGEF

2009

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PDZ-RhoGEF is a member of the regulator of G protein signaling (RGS) domain-containing RhoGEFs (RGS-RhoGEFs) that link activated heterotrimeric G protein α subunits of the G12 family to activation of the small GTPase RhoA. Unique among the RGS-RhoGEFs, PDZ-RhoGEF contains a short sequence that localizes the protein to the actin cytoskeleton. In this report, we demonstrate that the actin-binding domain, located between amino acids 561-585, directly binds to F-actin in vitro. Extensive mutagenesis identifies isoleucine 568, isoleucine 569, phenylalanine 572, and glutamic acid 573 as necessary for binding to actin and for co-localization with the actin cytoskeleton in cells. These results define a novel actin-binding sequence in PDZ-RhoGEF with a critical amino acid motif of IIxxFE. Moreover, sequence analysis identifies a similar actin-binding motif in the Nterminus of the RhoGEF frabin, and, as with PDZ-RhoGEF, mutagenesis and actin interaction experiments demonstrate a motif of LIxxFE, consisting of the key amino acids leucine 23, isoleucine 24, phenylalanine 27, and glutamic acid 28. Taken together, results with PDZ-RhoGEF and frabin identify a novel actin binding sequence. Lastly, inducible dimerization of the actin-binding region of PDZ-RhoGEF revealed a dimerization-dependent actin bundling activity in vitro. PDZ-RhoGEF exists in cells as a dimer, raising the possibility that PDZ-RhoGEF could influence actin structure independent of its ability to activate RhoA. KeywordsG protein; Rho; guanine-nucleotide exchange factor; actin; localization Rho family GTPases are members of the Ras super family of monomeric G-proteins (1). The Rho family comprises six small GTPase subfamilies including Rho, Rac, Cdc42, Rnd, RhoBTB and RhoT/Miro (2). Out of these, the most well studied members include Rho (A, B and C), Rac (1 and 2) and Cdc42 proteins. Their roles in cell regulation include modulation of cytoskeletal structure, motility, cell division, gene transcription, vesicular transport and various enzymatic activities. As key regulators of the actin cytoskeleton, in fibroblasts, RhoA induces the formation of actin stress fibers and focal adhesions, Rac1 stimulates the protrusion of lamellipodia and membrane ruffles and Cdc42 promotes extension of filopodia and actin microspikes (3)(4)(5). Rho GTPases are found in all eukaryotic cells and so far twenty-two mammalian genes encoding Rho GTPases have been described (6).+ This work was supported by NIH grant GM62884 (P.B.W.). *Corresponding Author: Philip B. Wedegaertner, Ph.D., Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 S. 10 th St., 839 BLSB, Philadelphia, PA 19107, tel: 215-503-3137, fax: 215-923-2117, P_Wedegaertner@mail.jci.tju.edu. Supporting information available: A figure showing an actin polymerization assay is available as Supplemental Figure S1. This material is available free of charge via the Internet at http://pubs.acs.org. NIH Public Access Author ManuscriptBiochemistry. Author manuscript; available in PMC 2010 ...

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“…Viral supernatants were collected at 48 and 72 hours, and used to infect target cells following standard protocols (Hu et al, 2008). Transduced cells were selected using either cell sorting or antibiotics.…”

Section: Methodsmentioning

confidence: 99%

Allosteric Activation of Functionally Asymmetric RAF Kinase Dimers

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et al. 2013

Cell

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Summary Although RAF kinases are critical for controlling cell growth, their mechanism of activation is incompletely understood. Recently, dimerization was shown to be important for activation. Here we show that the dimer is functionally asymmetric with one kinase functioning as an activator to stimulate activity of the partner, receiver kinase. The activator kinase did not require kinase activity, but did require N-terminal phosphorylation that functioned allosterically to induce cis-autophosphorylation of the receiver kinase. Based on modeling of the hydrophobic spine assembly, we also engineered a constitutively active mutant that was independent of Ras, dimerization, and activation loop phosphorylation. Since N-terminal phosphorylation of BRAF is constitutive, BRAF initially functions to activate CRAF. N-terminal phosphorylation of CRAF was dependent on MEK suggesting a feedback mechanism and explaining a key difference between BRAF and CRAF. Our work illuminates distinct steps in RAF activation that function to assemble the active conformation of the RAF kinase.

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Lsc activity is controlled by oligomerization and regulates integrin adhesion

Cited by 19 publications

References 61 publications

Thromboxane Receptor Signaling Is Required for Fibronectin-induced Matrix Metalloproteinase 9 Production by Human and Murine Macrophages and Is Attenuated by the Arhgef1 Molecule

Thromboxane Receptor Signaling Is Required for Fibronectin-induced Matrix Metalloproteinase 9 Production by Human and Murine Macrophages and Is Attenuated by the Arhgef1 Molecule

The Amino Acid Motif L/IIxxFE Defines a Novel Actin-Binding Sequence in PDZ-RhoGEF

Allosteric Activation of Functionally Asymmetric RAF Kinase Dimers

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