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MRAP2 regulates energy homeostasis by promoting primary cilia localization of MC4R
Adelaide Bernard, … , Jeremy F. Reiter, Christian Vaisse
Adelaide Bernard, … , Jeremy F. Reiter, Christian Vaisse
Published January 24, 2023
Citation Information: JCI Insight. 2023;8(2):e155900. https://doi.org/10.1172/jci.insight.155900.
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Research Article Endocrinology Metabolism

MRAP2 regulates energy homeostasis by promoting primary cilia localization of MC4R

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Abstract

The G protein–coupled receptor melanocortin-4 receptor (MC4R) and its associated protein melanocortin receptor–associated protein 2 (MRAP2) are essential for the regulation of food intake and body weight in humans. MC4R localizes and functions at the neuronal primary cilium, a microtubule-based organelle that senses and relays extracellular signals. Here, we demonstrate that MRAP2 is critical for the weight-regulating function of MC4R neurons and the ciliary localization of MC4R. More generally, our study also reveals that GPCR localization to primary cilia can require specific accessory proteins that may not be present in heterologous cell culture systems. Our findings further demonstrate that targeting of MC4R to neuronal primary cilia is essential for the control of long-term energy homeostasis and suggest that genetic disruption of MC4R ciliary localization may frequently underlie inherited forms of obesity.

Authors

Adelaide Bernard, Irene Ojeda Naharros, Xinyu Yue, Francois Mifsud, Abbey Blake, Florence Bourgain-Guglielmetti, Jordi Ciprin, Sumei Zhang, Erin McDaid, Kellan Kim, Maxence V. Nachury, Jeremy F. Reiter, Christian Vaisse

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Figure 3

MRAP2 colocalizes with MC4R at the primary cilia in vivo.

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MRAP2 colocalizes with MC4R at the primary cilia in vivo.
(A–C) MRAP2 lo...
(A–C) MRAP2 localizes to primary cilia in vivo. (A) Mice expressing a transgene encoding a ciliary GFP (Arl13-GFP) were used in this experiment. (B) Representative low-magnification image of the PVN (representative of n = 3) and nuclei (Hoescht, cyan). Magenta square indicates higher-magnification image, depicted in C. Scale bar: 200 μm. (C) Immunofluorescence image of cilia (Arl13b-GFPtg, yellow), MRAP2 (magenta), and nuclei (Hoechst, cyan) in the mouse PVN, showing that MRAP2 localizes to primary cilia (arrows). (D–F) MRAP2 colocalizes with MC4R in vivo (arrows and boxes). (D) Mouse line expressing a GFP tag in frame at the C-terminus of the endogenous Mc4r locus. (E) Representative low-magnification image of the PVN (representative of n = 3) and nuclei (Hoescht, cyan). Magenta square indicates higher magnification image, depicted in F. Scale bar: 200 μm. (F) Immunofluorescence image of MC4R-GFP (yellow), MRAP2 (Magenta). and nuclei (Hoechst, cyan) in the mouse PVN. Indicated boxed regions are shown to the right at higher magnification. Scale bars: 20 μm (low-powered images) and 5 μm (high-powered images). Brains were collected from P6 mice. 3V, third ventricle; PVN, paraventricular nucleus of the hypothalamus. Arrowheads indicate cilia expressing both MRAP2 and arl13-GFP (A–C) or MRAP2 and MC4R (D–F).

Copyright © 2023 American Society for Clinical Investigation
ISSN 2379-3708

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