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Wu CY, Lin MW, Wu DC, Huang YB, Huang HT, Chen CL. The role of phosphoinositide-regulated actin reorganization in chemotaxis and cell migration. Br J Pharmacol 2014; 171:5541-54. [PMID: 25420930 DOI: 10.1111/bph.12777] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 04/15/2014] [Accepted: 05/07/2014] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Reorganization of the actin cytoskeleton is essential for cell motility and chemotaxis. Actin-binding proteins (ABPs) and membrane lipids, especially phosphoinositides PI(4,5)P2 and PI(3,4,5)P3 are involved in the regulation of this reorganization. At least 15 ABPs have been reported to interact with, or regulated by phosphoinositides (PIPs) whose synthesis is regulated by extracellular signals. Recent studies have uncovered several parallel intracellular signalling pathways that crosstalk in chemotaxing cells. Here, we review the roles of ABPs and phosphoinositides in chemotaxis and cell migration. LINKED ARTICLES This article is part of a themed section on Cytoskeleton, Extracellular Matrix, Cell Migration, Wound Healing and Related Topics. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-24.
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Affiliation(s)
- C-Y Wu
- Department of Biological Science, National Sun Yat-sen University, Kaohsiung, Taiwan; Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, Kaohsiung, Taiwan
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102
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Abstract
The human genome encodes several hundred E3 ubiquitin ligases containing RING domains, and around 28 containing HECT domains. These enzymes catalyze the transfer of ubiquitin from E2 enzyme thioesters to a huge range of substrates and play crucial roles in many cellular functions. This makes them attractive potential therapeutic targets. However, they have proven difficult to inhibit: very few good inhibitors exist for RING domain ligases, and none have been described for HECT ligases. Here we show that bicyclic peptides isolated by phage display [Heinis C, Rutherford T, Freund S, Winter G (2009) Nat Chem Biol. 5(7):502-507] can target the E2 binding sites on the HECT domains of Smurf2, Nedd4, Mule/Huwe1, and WWP1, and thus act as specific inhibitors of these enzymes in vitro. By screening for displacement of one of these peptides from Smurf2, we were able to identify a small molecule, heclin (HECT ligase inhibitor), which inhibits several HECT ligases in tissue culture cells. In vitro, heclin does not block E2 binding but causes a conformational change that results in oxidation of the active site Cys. This demonstrates that HECT domains are potentially druggable and provides molecules that may be of experimental use. Heclin kills HEK293 cells growing in culture, consistent with an essential role for HECT ligase activity in mammalian cells.
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103
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Luo L, Wall AA, Yeo JC, Condon ND, Norwood SJ, Schoenwaelder S, Chen KW, Jackson S, Jenkins BJ, Hartland EL, Schroder K, Collins BM, Sweet MJ, Stow JL. Rab8a interacts directly with PI3Kγ to modulate TLR4-driven PI3K and mTOR signalling. Nat Commun 2014; 5:4407. [PMID: 25022365 DOI: 10.1038/ncomms5407] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 06/16/2014] [Indexed: 02/06/2023] Open
Abstract
Toll-like receptor 4 (TLR4) is activated by bacterial lipopolysaccharide (LPS) to mount innate immune responses. The TLR4-induced release of pro- and anti-inflammatory cytokines generates robust inflammatory responses, which must then be restrained to avoid disease. New mechanisms for the critical regulation of TLR-induced cytokine responses are still emerging. Here we find TLR4 complexes localized in LPS-induced dorsal ruffles on the surface of macrophages. We discover that the small GTPase Rab8a is enriched in these ruffles and recruits phosphatidylinositol 3-kinase (PI3Kγ) as an effector by interacting directly through its Ras-binding domain. Rab8a and PI3Kγ function to regulate Akt signalling generated by surface TLR4. Rab8a and PI3Kγ do not affect TLR4 endocytosis, but instead regulate mammalian target of rapamycin signalling as a mechanism for biasing the cytokine profile to constrain inflammation in innate immunity.
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Affiliation(s)
- Lin Luo
- 1] Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia [2]
| | - Adam A Wall
- 1] Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia [2]
| | - Jeremy C Yeo
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nicholas D Condon
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Suzanne J Norwood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Simone Schoenwaelder
- 1] Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia [2] Heart Research Institute & Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Kaiwen W Chen
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Shaun Jackson
- 1] Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia [2] Heart Research Institute & Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Brendan J Jenkins
- Centre for Innate Immunity and Infectious Diseases, MIMR-PHI Institute of Medical Research, Monash University, 27-31 Wright Street, Clayton, Victoria 3168, Australia
| | - Elizabeth L Hartland
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria 3010, Australia
| | - Kate Schroder
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Brett M Collins
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Matthew J Sweet
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jennifer L Stow
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
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