Src-dependent phosphorylation of caveolin-1 Tyr-14 promotes swelling and release of caveolae

• Published in: Molecular biology of the cell Vol. 27; no. 13; pp. 2090 - 2106
• Main Authors: Zimnicka, Adriana M, Husain, Yawer S, Shajahan, Ayesha N, Sverdlov, Maria, Chaga, Oleg, Chen, Zhenlong, Toth, Peter T, Klomp, Jennifer, Karginov, Andrei V, Tiruppathi, Chinnaswamy, Malik, Asrar B, Minshall, Richard D
• Format: Journal Article
• Language: English
• Published: United States The American Society for Cell Biology 01.07.2016
• Series: A Highlights from
• Subjects: Animals; Biological Transport; Caveolae - metabolism; Caveolin 1 - genetics; Caveolin 1 - metabolism; Cell Culture Techniques; Cell Membrane - metabolism; Endocytosis - physiology; HEK293 Cells; Humans; Mice; Mice, Knockout; Phosphorylation; Protein Transport; src-Family Kinases - metabolism
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.e15-11-0756

Caveolin 1 (Cav1) is a required structural component of caveolae, and its phosphorylation by Src is associated with an increase in caveolae-mediated endocytosis. Here we demonstrate, using quantitative live-cell 4D, TIRF, and FRET imaging, that endocytosis and trafficking of caveolae are associated with a Cav1 Tyr-14 phosphorylation-dependent conformational change, which spatially separates, or loosens, Cav1 molecules within the oligomeric caveolar coat. When tracked by TIRF and spinning-disk microscopy, cells expressing phosphomimicking Cav1 (Y14D) mutant formed vesicles that were greater in number and volume than with Y14F-Cav1-GFP. Furthermore, we observed in HEK cells cotransfected with wild-type, Y14D, or Y14F Cav1-CFP and -YFP constructs that FRET efficiency was greater with Y14F pairs than with Y14D, indicating that pY14-Cav1 regulates the spatial organization of Cav1 molecules within the oligomer. In addition, albumin-induced Src activation or direct activation of Src using a rapamycin-inducible Src construct (RapR-Src) led to an increase in monomeric Cav1 in Western blots, as well as a simultaneous increase in vesicle number and decrease in FRET intensity, indicative of a Src-mediated conformational change in CFP/YFP-tagged WT-Cav1 pairs. We conclude that phosphorylation of Cav1 leads to separation or "spreading" of neighboring negatively charged N-terminal phosphotyrosine residues, promoting swelling of caveolae, followed by their release from the plasma membrane.