CD44 interaction with ankyrin and IP3 receptor in lipid rafts promotes hyaluronan-mediated Ca2+ signaling leading to nitric oxide production and endothelial cell adhesion and proliferation.
In this study, we have showed that aortic endothelial cells (GM7372A cell line) express CD44v10 [a hyaluronan (HA) receptor], which is significantly enriched in cholesterol-containing lipid rafts (characterized as caveolin-rich plasma membrane microdomains). HA binding to CD44v10 promotes recruitment of the cytoskeletal protein, ankyrin and inositol 1,4,5-triphosphate (IP3) receptor into cholesterol-containing lipid rafts. The ankyrin repeat domain (ARD) of ankyrin is responsible for binding IP3 receptor to CD44v10 at lipid rafts and subsequently triggering HA/CD44v10-mediated intracellular calcium (Ca2+) mobilization leading to a variety of endothelial cell functions such as nitric oxide (NO) production, cell adhesion and proliferation. Further analyses indicate (i) disruption of lipid rafts by depleting cholesterol from the membranes of GM7372A cells (using methyl-beta-cyclodextrin treatment) or (ii) interference of endogenous ankyrin binding to CD44 and IP3 receptor using overexpression of ARD fragments (by transfecting cells with ARDcDNA) not only abolishes ankyrin/IP3 receptor accumulation into CD44v10/cholesterol-containing lipid rafts, but also blocks HA-mediated Ca2+ signaling and endothelial cell functions. Taken together, our findings suggest that CD44v10 interaction with ankyrin and IP3 receptor in cholesterol-containing lipid rafts plays an important role in regulating HA-mediated Ca2+ signaling and endothelial cell functions such as NO production, cell adhesion and proliferation.
Singleton
Patrick A
PA
Endocrine Unit, Department of Medicine, University of California-San Francisco and VA Medical Center, San Francisco, CA 94121, USA.
Bourguignon
Lilly Y W
LY
D000818:Animals; D017487:Ankyrins / Q000502:physiology*; D001011:Aorta; D015220:Calcium Channels / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology*; D002417:Cattle; D002448:Cell Adhesion / Q000502:physiology*; D002455:Cell Division / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D018960:Hyaluronan Receptors / Q000502:physiology*; D006820:Hyaluronic Acid / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D021962:Membrane Microdomains / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology*
D017487:Ankyrins; D015220:Calcium Channels; D018960:Hyaluronan Receptors; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D009569:Nitric Oxide; D006820:Hyaluronic Acid