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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 4

MRAP2 is required for MC4R localization to the primary cilia.

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MRAP2 is required for MC4R localization to the primary cilia.
(A and B) ...
(A and B) Immunofluorescence images of MC4R-GFP (yellow), cilia (ADCY3, magenta) and nuclei (Hoechst, cyan). Top panels: dashed lines delineate the PVNs. Scale bar: 50 μm. Bottom panels: High-magnification images. Scale: 5 μm. Arrowheads indicate MC4R-GFP+ cilia. (C) Quantitation of MC4R-GFP fluorescence intensity at the primary cilium (in arbitrary units). MC4R ciliary localization is decreased in the absence of MRAP2. (D) Quantitation of MC4R enrichment at the primary cilium as: (integrated density at the cilium)/(integrated density in an equal area of the cell body). Enrichment > 1 indicates higher localization of MC4R-GFP at the primary cilium than at the cell body. MC4R localization was quantified from 2 PVNs per P6 Mc4rgfp Mrap2+/+ (n = 2) and Mc4rgfp Mrap2–/– (n = 3) mice; 60–90 cilia we quantified per mouse. Data are represented as superplots displaying individual cilia intensity and enrichment values (small dots), and 2-tailed Student’s t tests were performed on the averages per mouse (big dots), represented as mean ± SEM; *P < 0.05, **P < 0.01.

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

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