Abstract

Adipocytes possess remarkable adaptive capacity to respond to nutrient excess, fasting or cold exposure, and they are thus an important cell type for the maintenance of proper metabolic health. Although the endoplasmic reticulum (ER) is a critical organelle for cellular homeostasis, the mechanisms that mediate adaptation of the ER to metabolic challenges in adipocytes are unclear. Here we show that brown adipose tissue (BAT) thermogenic function requires an adaptive increase in proteasomal activity to secure cellular protein quality control, and we identify the ER-localized transcription factor nuclear factor erythroid 2–like 1 (Nfe2l1, also known as Nrf1) as a critical driver of this process. We show that cold adaptation induces Nrf1 in BAT to increase proteasomal activity and that this is crucial for maintaining ER homeostasis and cellular integrity, specifically when the cells are in a state of high thermogenic activity. In mice, under thermogenic conditions, brown-adipocyte-specific deletion of Nfe2l1 (Nrf1) resulted in ER stress, tissue inflammation, markedly diminished mitochondrial function and whitening of the BAT. In mouse models of both genetic and dietary obesity, stimulation of proteasomal activity by exogenously expressing Nrf1 or by treatment with the proteasome activator PA28α in BAT resulted in improved insulin sensitivity. In conclusion, Nrf1 emerges as a novel guardian of brown adipocyte function, providing increased proteometabolic quality control for adapting to cold or to obesity.

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Acknowledgements

We are grateful to K. Claiborn for her expert editorial input, M. McGrath for his support of the project, M. Yilmaz, Y. Lee and V. Byles for assistance with experiments, K. Seedorf, P. Delerive and Servier for their continuous support of the project, R. Bronson and the Harvard Medical School Rodent Histopathology Core, M. Ericson and the Harvard Medical School Electron Microscopy Facility, N. Lupoli and the Harvard T.H. Chan School of Public Health Trace Metals Laboratory, and R. Kunz and the Thermo Fisher Scientific Center for Multiplexed Proteomics at Harvard Medical School and the Harvard T.H. Chan School of Public Health Animal Facility team for their support of the project. We acknowledge the prosperous scientific environment in the Hotamisligil lab and thank all lab members for their critical input and discussions. We are grateful to X. Wang (University of South Dakota) for generously sharing the PA28α-expressing adenovirus, E. Rosen (Beth Israel Deaconess Medical Center) for providing us with the Ucp1–Cre and the Adipoq–Cre mouse models and T. Iwawaki (Gunma University) for the conditional Ern1-deletion mouse model. A.B. was supported by a Deutsche Forschungsgemeinschaft Research Fellowship (BA 4925/1-1). S.B.W. was supported by a Canadian Institutes of Health Research fellowship. C.S. was supported by a University Medical Center Hamburg–Eppendorf MD/PhD program fellowship. R.L.S.G. was supported by the Barth Syndrome Foundation. This work has received support in part from the US National Institutes of Health (NIH) through the Laser Biomedical Research Center grants P41-EB015871 (M.G.B.) and 5-U54-CA151884 (M.G.B.), by the National Science Foundation grant ECCS-1449291 (D.F. and M.G.B.) and by the Massachusetts Institute of Technology through the Institute for Soldier Nanotechnologies grant W911NF-13-D-0001 (M.G.B.). D.F. was supported by a fellowship of the Boehringer Ingelheim Fonds. O.T.B. was supported by a European Molecular Biology Organization Long-term Fellowship. Y.-H.T. and L.O.L. were supported in part by NIH grants R01DK077097, R01DK102898 and P30DK036836. M.D.L. was supported by NIH grants T32DK007260, F32DK102320 and K01DK111714. A.P.A. was supported by the Pew Foundation. We apologize to colleagues whose work we could not cite due to space limitations. The study was supported by an industry-sponsored research agreement between Harvard University and Servier.

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Author notes

    • Oliver T Bruns

    Present address: Helmholtz Pioneer Campus (HPC), Helmholtz Zentrum München, Neuherberg, Germany.

    • Alexander Bartelt
    •  & Scott B Widenmaier

    These authors contributed equally to this work.

Affiliations

  1. Department of Genetics and Complex Diseases and Sabri Ülker Center, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.

    • Alexander Bartelt
    • , Scott B Widenmaier
    • , Christian Schlein
    • , Kornelia Johann
    • , Renata L S Goncalves
    • , Kosei Eguchi
    • , Alexander W Fischer
    • , Günes Parlakgül
    • , Nicole A Snyder
    • , Truc B Nguyen
    • , Karen E Inouye
    • , Ana Paula Arruda
    •  & Gökhan S Hotamisligil
  2. Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, USA.

    • Oliver T Bruns
    • , Daniel Franke
    •  & Moungi G Bawendi
  3. Section on Integrative Physiology and Metabolism, Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, USA.

    • Matthew D Lynes
    • , Luiz O Leiria
    •  & Yu-Hua Tseng
  4. Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.

    • Gökhan S Hotamisligil

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Contributions

A.B. and S.B.W. designed the study, were involved in all aspects of the experiments, analyzed all data and wrote the manuscript; C.S. and K.J. performed in vitro experiments; R.L.S.G. performed mitochondrial isolations and Seahorse experiments; K.E. performed flow cytometry experiments; A.W.F. performed immunohistochemistry; G.P., N.A.S. and T.B.N. were involved in animal experiments; O.T.B., D.F. and M.G.B. developed quantum dots and performed SWIR imaging; L.O.L. performed thermal imaging; M.D.L. and Y.-H.T. performed bioinformatics analyses; A.P.A. and K.E.I. helped with the design of the study and animal experiments; and G.S.H. supervised the design and execution of the study, interpreted the results and wrote the manuscript. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Gökhan S Hotamisligil.

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DOI

https://doi.org/10.1038/nm.4481