Cell membrane extensions, generated by mechanical constraint, are associated with a sustained lipid raft patching and an increased cell signaling.
Platelet activation triggers an imbalance in plasma membrane phospholipids by a specific aminophospholipid outflux, resulting in filopodia formation. Similarly, the addition of a phospholipid excess in the outer leaflet of the plasma membrane induces cellular extensions and actin polymerization. The implication of membrane microdomains in sustaining these mechanical constraints remains, however, unknown and was investigated in human platelets and mouse fibroblasts. The disruption of lipid rafts by cholesterol depletion prevents actin polymerization and formation of cellular extensions. Phospholipid excess triggers raft patching underneath the cell extensions, recruitment of protein raft markers and increase of tyrosine phosphorylation of raft proteins. Using a mass spectrometric analysis of isolated platelet rafts, we identified tyrosine kinases and proteins implicated in the formation of cell membrane extensions, cell adhesion and motility. They are recruited to rafts in response to a mechanical constraint. Taken together, our results demonstrate that exogenous phospholipid addition causes a modulation of the lateral plasma membrane organization and an activation of the cell signaling triggering actin remodeling and the formation of cellular protrusions. Raft disruption abolishes these processes, demonstrating that their integrity is crucial for cell shape changes in response to a mechanical constraint on plasma membrane.
Larive
Romain M
RM
Universités de Montpellier 2 & 1, Centre de Recherche de Biochimie Moléculaire CRBM, CNRS-UMR 5237, 1919 Route de Mende, F-34293 Montpellier cedex 5, France. romain.larive@usal.es
Baisamy
Laurent
L
Urbach
Serge
S
Coopman
Peter
P
Bettache
Nadir
N
D000199:Actins / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002460:Cell Line; D022081:Cell Surface Extensions / Q000187:drug effects / Q000378:metabolism; D002784:Cholesterol / Q000172:deficiency; D003902:Detergents / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D010743:Phospholipids / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D040901:Proteomics; D015398:Signal Transduction / Q000187:drug effects; D013314:Stress, Mechanical
D000199:Actins; D015415:Biomarkers; D003902:Detergents; D008565:Membrane Proteins; D010743:Phospholipids; D019000:Phosphotyrosine; D002784:Cholesterol