Katagiri, K., Maeda, A., Shimonaka, M. & Kinashi, T. RAPL, a Rap1-binding molecule that mediates Rap1-induced adhesion through spatial regulation of LFA-1. Nat. Immunol. 4, 741−748

ArticleinNature Immunology 4(8):741-8 · September 2003with8 Reads
Impact Factor: 20.00 · DOI: 10.1038/ni950 · Source: PubMed
Abstract

The small GTPase Rap1 is a potent activator of leukocyte integrin. However, the regulatory mechanism involved is unknown. Here, we identify the Rap1 effector, RAPL, as an essential regulator in this activation. RAPL was enriched in mouse lymphoid tissues and associated with Rap1 after stimulation by the T cell receptor and with chemokine CXCL12. Human RAPL stimulated lymphocyte polarization and the patch-like redistribution of lymphocyte-function-associated antigen 1 (LFA-1) to the leading edge, resulting in enhanced adhesion to intercellular adhesion molecule 1 (ICAM-1). Triggered by activated Rap1, RAPL associated with LFA-1 and rapidly relocated to the leading edge and accumulated at immunological synapses. Thus, RAPL regulates lymphocyte adhesion through the spatial distribution of LFA-1.

    • "...hed in lymphoid tissues) in T-cells [18,19,[21][22][23][24]. Rap1 [25][26][27][28]also binds RapL [29,30] and RIAM (Rap1-interacting adaptor molecule) [31]. Talin is a ubiquitous high-molecular-weight p..."
      Adaptors ADAP (adhesion and degranulation–promoting adaptor protein) (HUGO official designation: Fyb) [15][16][17]and SKAP1 (src kinase associated phosphoprotein 1: HUGO official designation; also SKAP-55, src kinase-associated phosphoprotein-55) are also needed for 1 and 2 integrin activation [18][19][20]. In fact, we have shown that SKAP1 is an effector is the inside-out pathway by interacting with RapL (regulator of cell adhesion and polarisation enriched in lymphoid tissues) in T-cells [18,19,[21][22][23][24]. Rap1 [25][26][27][28]also binds RapL [29,30] and RIAM (Rap1-interacting adaptor molecule) [31]. Talin is a ubiquitous high-molecular-weight protein of the cytoskeleton that is essential for the activation of integrins [32,33].
    [Show abstract] [Hide abstract] ABSTRACT: While the cytoskeletal protein talin binds to the β-chain of LFA-1, the immune cell adaptor SKAP1 (SKAP-55) binds to the α-chain of the same integrin via RapL. Whereas calpain protease cleavage of talin is important for LFA-1 activation, it has been unclear whether SKAP1 can alter the function of talin or its associated adaptor RIAM in T-cells. In this paper, we report that Skap1-/- T-cells showed a reduction in the translocation of talin and RIAM to the contact interface of T-cells with antigenic beads or dendritic cells (DCs) presenting OVA peptide to OT-1 T-cells. In addition, Skap1-/- T-cells show an altered pattern of talin cleavage, while the expression of a cleavage resistant form of talin (L432G) restored the impaired adhesion of OT1 transgenic Skap1-/- T-cells with DCs. SKAP1 therefore can affects the function of talin in T-cells needed for optimal T-cell/DC conjugation.
    Full-text · Article · Feb 2016 · Immunology Letters
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    • "...]. RapL is one of the Rap1 downstream effectors, which was identified by a yeast two-hybrid screen [89,274]. RapL binds to a site consisting of two lysine residues (K1097/K1099) following the GFFKR motif..."
      During integrin activation, activated Rap1 needs to be recruited to the plasma membrane by a signaling module comprising the cytosolic adapter proteins ADAP (adhesion and degranulation promoting adapter protein) and SKAP55 (src kinase-associated protein of 55 kDa) [273]. RapL is one of the Rap1 downstream effectors, which was identified by a yeast two-hybrid screen [89,274]. RapL binds to a site consisting of two lysine residues (K1097/K1099) following the GFFKR motif, which is found only in the α L [90] subunit.
    [Show abstract] [Hide abstract] ABSTRACT: Integrins are a group of heterodimeric transmembrane receptors that play essential roles in cell-cell and cell-matrix interaction. Integrins are important in many physiological processes and diseases. Integrins acquire affinity to their ligand by undergoing molecular conformational changes called activation. Here we review the molecular biomechanics during conformational changes of integrins, integrin functions in leukocyte biorheology (adhesive functions during rolling and arrest) and molecules involved in integrin activation.
    Full-text · Article · Dec 2015 · Biorheology
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    • "...lated T-cell adhesion involving αLβ2, with no or lesser roles in α4β1-mediated adhesion (Katagiri et al., 2003; Ghandour et al., 2007; Bolomini-Vittori et al., 2009). Instead, the Vav1-Rac1 pathway is required f..."
      Moreover, Vav1 and SLP-76 (Supplemental Figure S1C, right) et al., 2009). Of note, the RAPL-Rap1 and Rho/Rac-phospholipase D pathways are critical for chemokine-stimulated T-cell adhesion involving αLβ2, with no or lesser roles in α4β1-mediated adhesion (Katagiri et al., 2003; Ghandour et al., 2007; Bolomini-Vittori et al., 2009). Instead, the Vav1-Rac1 pathway is required for T-cell adhesion involving α4β1 upon exposure to chemokines (Garcia-Bernal et al., 2005 ).
    [Show abstract] [Hide abstract] ABSTRACT: Stimulation by chemokines of integrin α4β1-dependent T lymphocyte adhesion is a crucial step for lymphocyte trafficking. The adaptor Vav1 is required for chemokine-activated T-cell adhesion mediated by α4β1. Conceivably, proteins associating with Vav1 could potentially modulate this adhesion. Correlating with activation by the chemokine CXCL12 of T lymphocyte attachment to α4β1 ligands, a transient stimulation in the association of Vav1 with SLP-76, Pyk2 and ADAP was observed. Using T-cells depleted for SLP-76, ADAP or Pyk2, or expressing Pyk2 kinase inactive forms, we show that SLP-76 and ADAP stimulate chemokine-activated, α4β1-mediated adhesion, whereas Pyk2 opposes T-cell attachment. While CXCL12-promoted generation of high-affinity α4β1 is independent of SLP-76, ADAP and Pyk2, the strength of α4β1-VCAM-1 interaction and cell spreading on VCAM-1 are targets of regulation by these three proteins. GTPase assays, expression of activated or dominant negative Rac1, or combined ADAP and Pyk2 silencing indicated that Rac1 activation by CXCL12 is a common mediator response in SLP-76-, ADAP- and Pyk2-regulated cell adhesion involving α4β1. Our data strongly suggest that chemokine-stimulated associations between Vav1, SLP-76 and ADAP facilitate Rac1 activation and α4β1-mediated adhesion, whereas Pyk2 opposes this adhesion by limiting Rac1 activation. © 2015 by The American Society for Cell Biology.
    Full-text · Article · Jul 2015 · Molecular biology of the cell
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    • "...ins (e.g., RAPL) that may contribute to proangiogenic signal. GTP-bound Rap1 to activate integrins [55]. This pathway has proved essential in angiogenic sprouting, ECs migration (HUVECs), adhesion, and i..."
      In addition, Rap1 stimulates different proteins (e.g., RAPL) that may contribute to proangiogenic signal. GTP-bound Rap1 to activate integrins [55]. This pathway has proved essential in angiogenic sprouting, ECs migration (HUVECs), adhesion, and in vivo neovascularization (hind limb ischemia model in mice) [56].
    [Show abstract] [Hide abstract] ABSTRACT: Vasculature is present in all tissues and therefore is indispensable for development, biology, and pathology of multicellular organisms. Endothelial cells guarantee proper function of the vessels and are the original component in angiogenesis. Morphogenesis of the vascular system utilizes processes like cell adhesion, motility, proliferation, and survival that are closely related to the dynamics of actin filaments and actin-tethered adhesion complexes. Here we review involvement of actin cytoskeleton-associated junctional molecules of endothelial cells in angiogenesis and lymphangiogenesis. Particularly, we focus on F-actin binding protein afadin, an adaptor protein involved in broad range of signaling mechanisms. Afadin mediates the pathways of vascular endothelial growth factor- (VEGF-) and sphingosine 1-phosphate-triggered angiogenesis and is essential for embryonic development of lymph vessels in mice. We propose that targeting actin-tethered junctional molecules, including afadin, may present a new approach to angiogenic therapy that in combination with today used medications like VEGF inhibitors will benefit against development of pathological angiogenesis.
    Full-text · Article · Apr 2015
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    • "...1A was upregulated and involved in cell-cell and cell-extracellular matrix adhesion in many cancers323334. By firefly luciferase activity assay, miR-203 could reduce luciferase activity in the Rap1A wi..."
      Rap1 is a member of the Ras family of small GTPases and was activated in response to a number of extracellular stimuli [31]. Many studies have shown that Rap1A was upregulated and involved in cell-cell and cell-extracellular matrix adhesion in many cancers323334. By firefly luciferase activity assay, miR-203 could reduce luciferase activity in the Rap1A wildtype but had no effect on the mutant construct .
    [Show abstract] [Hide abstract] ABSTRACT: Objective Evidence supports an important role for miR-203 in the regulation of the proliferation, migration and invasion of prostate cancer (PCa) cells. However, the exact mechanisms of miR-203 in PCa are not entirely clear.Methods We examined the expression of miR-203 in prostate cancer tissues, adjacent normal tissues, PCa cell lines and normal prostate epithelial cells by qRT-PCR. Then, the effects of miR-203 or Rap1A on proliferation, adhesion and invasion of PCa cells were assayed using CKK-8, adhesion analysis, and transwell invasion assays. Luciferase reporter assay was performed to assess miR-203 binding to Rap1A mRNA. Tumor growth was assessed by subcutaneous inoculation of cells into BALB/c nude mice.ResultsHere, we confirmed that the expression of miR-203 was significantly downregulated in prostate cancer specimens compared with matched adjacent normal prostate specimens. Mechanistic dissection revealed that miR-203 mediated cell proliferation, adhesion and invasion in vitro, and tumor growth in vivo, as evidenced by reduced RAC1, p-PAK1, and p-MEK1 expression. In addition, we identified Rap1A as a direct target suppressed by miR-203, and there was an inverse relationship between the expression of miR-203 and Rap1A in PCa. Knockdown of Rap1A phenocopied the effects of miR-203 on PCa cell growth and invasion. Furthermore, Rap1A over-expression in PCa cells partially reversed the effects of miR-203-expression on cell adhesion and invasion.Conclusions These findings provide further evidence that a crucial role for miR-203 in inhibiting metastasis of PCa through the suppression of Rap1A expression.
    Full-text · Article · Jan 2015 · Journal of Experimental & Clinical Cancer Research
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    • "...fficking-dependent manner and associates with RAPL through the cytoplasmic region of the α L chain [32]. RAPL or Mst1-deficient T cells exhibit a defect of LFA-1 clustering at the leading edge [21,33]. ..."
      Integrin LFA-1, also known as CD11a/CD18 and integrin α L β 2 , is a major adhesion molecule involved in T cell trafficking. LFA-1 clusters at the leading edge of polarized cells stimulated with chemokine or anti-CD3 in an intracellular trafficking-dependent manner and associates with RAPL through the cytoplasmic region of the α L chain [32]. RAPL or Mst1-deficient T cells exhibit a defect of LFA-1 clustering at the leading edge [21,33].
    [Show abstract] [Hide abstract] ABSTRACT: The canonical Hippo/Mst pathway, originally discovered in Drosophila, is famous for its function in promoting apoptosis, inhibiting cell proliferation and tumorigenesis, and regulating tissue regeneration. However, emerging evidences show that multiple non-canonical Hippo signaling pathways are also implicated in the regulation of various other biological processes. Recent studies have revealed that Mst1/2, the core kinases of Hippo/Mst pathway are required for T cell development, function, survival, trafficking, homing, and also involved in regulation of autoimmunity. In this review, we discuss the roles of non-canonical Hippo/Mst signaling pathways in lymphocyte development and functions. © The Author 2014. Published by ABBS Editorial Office in association with Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences.
    Full-text · Article · Dec 2014 · Acta Biochimica et Biophysica Sinica
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