Characterization of brown adipose tissue in the human perirenal depot

Authors


  • Funding agencies: Funding was obtained from The Sahlgrenska Academy (to PAS and KL), The University of Gothenburg/Sahlgrenska University Hospital (LUA/ALF ALFGBG-11379, −140421 to PAS and MKS), the Regional FoU-support Västra Götalandsregionen (VGFOUREG-12052) and the Swedish Heart and Lung Foundation project (20100648 to KMS), 7TH Framework program International Research Staff Exchange Scheme (IRSES), FUEGO project to PAS.

  • Disclosure: The authors have no conflicts of interest to declare.

    Author Contributions: PAS, MR, JP, CD, MKS designed research, MJP, MR, JP, MKS performed patient and biopsy work, PAS, KL, JMH, MT, MJP, TMK, JP performed expression analysis, TMK, ALH, CD performed steam cell work, PAS, KL wrote the first draft of the paper, All authors provided critical revision of the manuscript.

Abstract

Objective

To characterize brown adipose tissue (BAT) in the human perirenal adipose tissue depot.

Method

Perirenal adipose tissue biopsies were obtained from 55 healthy kidney donors. Expression analysis was performed using microarray, real-time PCR, immunoblotting and immunohistochemistry. Additional studies using human stem cells were performed.

Results

UCP1 gene expression analysis revealed a large intra-individual variation in the perirenal adipose tissue biopsies. Both multi- and unilocular UCP1-positive adipocytes were detected in several of the adipose tissue samples analyzed by immunohistochemical staining. Microarray analysis identified 54 genes that were overexpressed in UCP1-positive perirenal adipose tissue. Real-time PCR analysis of BAT candidate genes revealed a set of genes that were highly correlated to UCP1 and a set of three transcription factor genes (PRDM16, PGC1α, and RXRγ) that were highly correlated to each other. RXRγ displayed nuclear immunoreactivity in brown adipocytes and an increased gene expression during brown adipogenesis in human stem cells.

Conclusion

Our data provides the first molecular characterization of BAT in the perirenal adipose tissue depot. Furthermore, it highlights the transcription factor RXRγ as a new player in BAT development.

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