title: Integrin-matrix clusters form podosome-like adhesions in the absence of traction forces.
abstract: Matrix-activated integrins can form different adhesion structures. We report that nontransformed fibroblasts develop podosome-like adhesions when spread on fluid Arg-Gly-Asp peptide (RGD)-lipid surfaces, whereas they habitually form focal adhesions on rigid RGD glass surfaces. Similar to classic macrophage podosomes, the podosome-like adhesions are protrusive and characterized by doughnut-shaped RGD rings that surround characteristic core components including F-actin, N-WASP, and Arp2/Arp3. Furthermore, there are 18 podosome markers in these adhesions, though they lack matrix metalloproteinases that characterize invadopodia and podosomes of Src-transformed cells. When nontransformed cells develop force on integrin-RGD clusters by pulling RGD lipids to prefabricated rigid barriers (metal lines spaced by 1-2 μm), these podosomes fail to form and instead form focal adhesions. The formation of podosomes on fluid surfaces is mediated by local activation of phosphoinositide 3-kinase (PI3K) and the production of phosphatidylinositol-(3,4,5)-triphosphate (PIP3) in a FAK/PYK2-dependent manner. Enrichment of PIP3 precedes N-WASP activation and the recruitment of RhoA-GAP ARAP3. We propose that adhesion structures can be modulated by traction force development and that production of PIP3 stimulates podosome formation and subsequent RhoA downregulation in the absence of traction force.
authors.affiliation: Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore. Electronic address: chyu@nus.edu.sg.
authors.forename: Cheng-han
authors.initials: CH
authors.lastname: Yu
authors.affiliation: Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore; Randall Division of Cell & Molecular Biophysics, King's College London, London SE1 1UL, UK.
authors.forename: Nisha Bte Mohd
authors.initials: NB
authors.lastname: Rafiq
authors.affiliation: Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.
authors.forename: Anitha
authors.initials: A
authors.lastname: Krishnasamy
authors.affiliation: Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Hartman
authors.affiliation: Randall Division of Cell & Molecular Biophysics, King's College London, London SE1 1UL, UK.
authors.forename: Gareth E
authors.initials: GE
authors.lastname: Jones
authors.affiliation: Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore; Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Bershadsky
authors.affiliation: Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore; Department of Biological Sciences, Columbia University, New York, NY, 10027, USA. Electronic address: ms2001@columbia.edu.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Sheetz
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D005109:Extracellular Matrix / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D020782:Matrix Metalloproteinases / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal / Q000378:metabolism
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D051417:Focal Adhesion Kinase 1; D051418:Focal Adhesion Kinase 2; D020690:GTPase-Activating Proteins; D016023:Integrins; D020782:Matrix Metalloproteinases; D009842:Oligopeptides; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; C495770:Wasl protein, rat; C060974:phosphatidylinositol 3,4,5-triphosphate; C047981:arginyl-glycyl-aspartic acid