Fatty acid mobilization from adipose tissue is mediated by CD36 posttranslational modifications and intracellular trafficking
Alexes C. Daquinag, Zhanguo Gao, Cale Fussell, Linnet Immaraj, Renata Pasqualini, Wadih Arap, Askar M. Akimzhanov, Maria Febbraio, Mikhail G. Kolonin
Alexes C. Daquinag, Zhanguo Gao, Cale Fussell, Linnet Immaraj, Renata Pasqualini, Wadih Arap, Askar M. Akimzhanov, Maria Febbraio, Mikhail G. Kolonin
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Research Article Cell biology Metabolism

Fatty acid mobilization from adipose tissue is mediated by CD36 posttranslational modifications and intracellular trafficking

Abstract

The mechanism controlling long-chain fatty acid (LCFA) mobilization from adipose tissue is not well understood. Here, we investigated how the LCFA transporter CD36 regulates this process. By using tissue-specific KO mouse models, we showed that CD36 in adipocytes and endothelial cells mediated both LCFA deposition into and release from adipose tissue. We demonstrated the role of adipocytic and endothelial CD36 in promoting tumor growth and chemoresistance conferred by adipose tissue–derived LCFAs. We showed that dynamic cysteine S-acylation of CD36 in adipocytes, endothelial cells, and cancer cells mediated intercellular LCFA transport. We demonstrated that lipolysis induction in adipocytes triggered CD36 deacylation and deglycosylation, as well as its dissociation from interacting proteins, prohibitin-1 (PHB) and annexin 2 (ANX2). Our data indicate that lipolysis triggers caveolar endocytosis and translocation of CD36 from the cell membrane to lipid droplets. This study suggests a mechanism for both outside-in and inside-out cellular LCFA transport regulated by CD36 S-acylation and its interactions with PHB and ANX2.

Authors

Alexes C. Daquinag, Zhanguo Gao, Cale Fussell, Linnet Immaraj, Renata Pasqualini, Wadih Arap, Askar M. Akimzhanov, Maria Febbraio, Mikhail G. Kolonin

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Figure 1

CD36 in adipocytes and the endothelium mediates LCFA transport in adipose tissue.

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CD36 in adipocytes and the endothelium mediates LCFA transport in adipos...
(A) Steady-state plasma concentration of free fatty acids (FFAs), higher in CD36 EC-KO and Ad-KO mice. n = 10 mice. (B) Body composition measured with EchoMRI and body weight (BW) revealed reduced adiposity in CD36-KO mice (n = 10 mice, 1-way ANOVA). (C) Reduced BODIPY-C16 uptake by adipocytes in CD36 Ad-KO and EC-KO mice. Visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and brown adipose tissue (BAT) were recovered 180 minutes after i.v. BODIPY-C16 injection and green fluorescence was imaged in cell suspension upon tissue digestion with collagenase. Scale bar: 50 μm; blue: DNA. (D) Western blotting confirmed KO of CD36 in 3T3-L1 cells. Images: lipid droplet formation in control and CD36-KO adipocytes differentiated for 5 days. Western blotting on proteins extracted from control and CD36-KO bEND.3 cells demonstrated loss of CD36, but not of PHB and ANX2, immunoblotted for as loading controls. Arrow: glycosylated CD36. Arrowhead: nonglycosylated CD36. Graphs: Western quantification in AU. Scale bar: 50 μm for all panels. (E) QBT assay demonstrating that LCFA uptake by CD36-null 3T3-L1 adipocytes and bEND.3 cells was inefficient compared with nondifferentiated (ND) cells. n = 5 wells. (F) Concentration of FFA in culture medium 3 hours after lipolysis induction in WT and CD36-null 3T3-L1 adipocytes (n = 10 wells, Student’s t test). (G) Relative increase in plasma concentration of FFA 15 minutes after isoproterenol injection observed in WT but not CD36-KO mice (n = 10 mice, 1-way ANOVA). In all panels, data are shown as mean ± SEM; *P < 0.01.