Adipose tissue stores excess calories as triacylglycerol (TAG) and cholesterol ester in lipid droplets (LDs) and mobilizes them as needed. Hence, adipose tissue is constantly remodeling, with obesity being a prominent example of active fat mobilization. How adipose tissue regulates LD packing in the different fat depots - white versus brown during obesity remains poorly understood. X-ray scattering of adipose tissue uncovered that LDs store TAG in two packing domains- a disordered core and a multilamellar shell. During obesity, the number of TAG layers increases in a manner that is adipose depot-specific.
We found that collagen is randomly dispersed in white fat forming a permissive environment for LD expansion. In contrast, collagen is highly oriented in brown fat restricting LD growth. Finally, we demonstrate that bile acids (BAs) in adipose tissue also have LD remodeling power.
During obesity there is alteration and reduced levels of highly hydrophobic BAs, chenodeoxycholic acid (CDCA). Loss of the BA receptor, Farnesoid X receptor (FXR) leads to enlarged adipocytes which are indicative of large LDs. In fact, CDCA, a major ligand of FXR, is sufficient to cause LD breakdown. These findings implicate that BA profiles, diet, and tissue niche dictate LD remodeling..
Cecilia Leal is an Associate Professor of Materials Science and Engineering at the University of Illinois at Urbana-Champaign (UIUC). Cecilia received a M.S. in Industrial Chemistry at the University of Coimbra, Portugal and a PhD in Physical Chemistry at the University of Lund, Sweden. She was a postdoctoral fellow at UC Santa Barbara before starting her appointment at UIUC in 2012. Cecilia received the 2020 & 2018 Dean's Award for Excellence in Research, the 2019 Provost Distinguished Promotion Award, and the 2016 NSF CAREER and NIH Director’s New Innovator Awards.
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