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 5

CD36 deacylation induced by lipolysis.

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CD36 deacylation induced by lipolysis. (A) Concentration of FFA in cultu...
(A) Concentration of FFA in culture medium 5 hours after lipolysis induction in 3T3-L1 adipocytes untreated or treated with an inhibitor of S-acylation, ML211 (30 nM). Data are shown as mean ± SEM; *P < 0.05 (Student’s t test). (B) ABE assay (Supplemental Figure 4A) on 3T3-L1 1adipocytes untreated or induced to undergo lipolysis for indicated time (minutes). Note that IP of S-acylated CD36, specifically observed upon hydroxylamine (HA) treatment, was partly inhibited by lipolysis. Immunoblotting for calnexin and ANX2 from the same extracts indicated constant ANX2 acylation and equal loading. Quantification is on the right. (C) CD36 metabolic labeling (Supplemental Figure 4B). After incubation of live 3T3-L1 adipocytes with alkynylated LCFA analog (0.1 mM 17-ODA, 12 hours), de novo S-acylation of CD36 was detected by IP with anti-CD36 antibodies, subsequent click chemistry with IRDye800-azide probe (IRDye800-N3), and SDS-PAGE. Note that IP of S-acylated CD36, specifically observed upon HA treatment, was inhibited by lipolysis induction (IBMX/forskolin/isoproterenol). Arrow: glycosylated CD36. Arrowhead: nonglycosylated CD36. CD36-IR800 quantification is on the right. (D) Probing of the IP blot from C with PHB and ANX2 antibodies, and subsequently with CD36 antibodies, demonstrated a decrease in PHB and ANX2 association with CD36 concomitant with a decrease of CD36 acylation upon lipolysis induction.