Review Article | Published:

Emerging nonmetabolic functions of skin fat

Nature Reviews Endocrinology volume 14, pages 163173 (2018) | Download Citation

Abstract

Although the major white adipose depots evolved primarily to store energy, secrete hormones and thermo-insulate the body, multiple secondary depots developed additional specialized and unconventional functions. Unlike any other fat tissue, dermal white adipose tissue (dWAT) evolved a large repertoire of novel features that are central to skin physiology, which we discuss in this Review. dWAT exists in close proximity to hair follicles, the principal appendages of the skin that periodically grow new hairs. Responding to multiple hair-derived signals, dWAT becomes closely connected to cycling hair follicles and periodically cycles itself. At the onset of new hair growth, hair follicles secrete activators of adipogenesis, while at the end of hair growth, a reduction in the secretion of activators or potentially, an increase in the secretion of inhibitors of adipogenesis, results in fat lipolysis. Hair-driven cycles of dWAT remodelling are uncoupled from size changes in other adipose depots that are controlled instead by systemic metabolic demands. Rich in growth factors, dWAT reciprocally signals to hair follicles, altering the activation state of their stem cells and modulating the pace of hair regrowth. dWAT cells also facilitate skin repair following injury and infection. In response to wounding, adipose progenitors secrete repair-inducing activators, while bacteria-sensing adipocytes produce antimicrobial peptides, thus aiding innate immune responses in the skin.

Key points

  • Dermal white adipose tissue (dWAT) is a specialized adipose depot of the skin with activities that are closely linked with those of hair follicles.

  • The development and remodelling of dWAT relies largely on paracrine signals generated by growing hair follicles.

  • Dermal adipocytes cyclically grow and shrink their lipid droplets in response to hair-derived signals and systemic factors, such as cold stress, can override this cycle.

  • Dermal adipocytes and their progenitors actively signal to neighbouring skin cell types, including hair follicle cells, and become important modulators of their growth activities.

  • Dermal adipogenesis is activated in response to bacterial skin infection, activates antimicrobial peptide secretion and serves an innate immune defence function.

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Acknowledgements

M.V.P. is supported by the NIH National Institute of Arthritis and Musculoskeletal and Skin (NIAMS) grants R01-AR067273 and R01-AR069653 and by a Pew Charitable Trust grant. C.F.G.-J. is supported by the US National Science Foundation Graduate Research Fellowship Program (NSF-GRFP) (DGE-1321846) and an Initiative for Maximizing Student Development (MBRS-IMSD) training grant (GM055246) and a Howard A. Schneiderman Graduate Fellowship Award.

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Affiliations

  1. Department of Developmental and Cell Biology, 2011 Biological Sciences III, University of California, Irvine, Irvine, California 92697, USA.

    • Christian F. Guerrero-Juarez
    •  & Maksim V. Plikus
  2. Sue and Bill Gross Stem Cell Research Center, 845 Health Sciences Road, University of California, Irvine, Irvine, California 92697, USA.

    • Christian F. Guerrero-Juarez
    •  & Maksim V. Plikus
  3. Center for Complex Biological Systems, 2620 Biological Sciences III, University of California, Irvine, Irvine, California 92697, USA.

    • Christian F. Guerrero-Juarez
    •  & Maksim V. Plikus

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C.F.G.-J. and M.V.P. researched data for the article, made substantial contributions to discussions of the content, wrote the article and reviewed and/or edited the article before submission.

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Correspondence to Maksim V. Plikus.

Glossary

Panniculus carnosus

A layer of striated muscle below dermal adipose tissue.

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https://doi.org/10.1038/nrendo.2017.162