Visfatin expression analysis in association with recruitment and activation of human and rodent brown and brite adipocytes

ABSTRACT

Human brown adipocytes are able to burn fat and glucose and are now considered as a potential strategy to treat obesity, type 2 diabetes and metabolic disorders. Besides their thermogenic function, brown adipocytes are able to secrete adipokines. One of these is visfatin, a nicotinamide phosphoribosyltransferase involved in nicotinamide dinucleotide synthesis, which is known to participate in the synthesis of insulin by pancreatic β cells. In a therapeutic context, it is of interest to establish whether a potential correlation exists between brown adipocyte activation and/or brite adipocyte recruitment, and adipokine expression. We analyzed visfatin expression, as a pre-requisite to its secretion, in rodent and human biopsies and cell models of brown/brite adipocytes. We found that visfatin was preferentially expressed in mature adipocytes and that this expression was higher in brown adipose tissue of rodents compared to other fat depots. However, using various rodent models we were unable to find any correlation between visfatin expression and brown or brite adipocyte activation or recruitment. Interestingly, the situation is different in humans where visfatin expression was found to be equivalent between white and brown or brite adipocytes in vivo and in vitro. In conclusion, visfatin can be considered only as a rodent brown adipocyte biomarker, independently of tissue activation.

KEYWORDS:

• hMADS
• nampt
• obesity
• PBEF
• type 2 diabetes
• UCP1

Disclosure of potential conflicts of interestxs

No potential conflicts of interest were disclosed.

Acknowledgments

The authors greatly acknowledge IBV and IRCAN Animal core facilities, as well as Octalia Technologies for manuscript editing.

Funding

This work was supported by CNRS, INSERM, Université de Nice Sophia Antipolis, EU FP7 project DIABAT (HEALTH-F2–2011–278373), French Agence Nationale de la Recherche (ANR-10-BLAN-1105 miRBAT and ANR-RPV12004AAA- DiamiR), Aviesan/AstraZeneca, “Diabetes and the vessel wall injury” program, “Investments for the Future” LABEX SIGNALIFE #ANR-11-LABX-0028–01 and European Foundation for the Study of Diabetes (EFSD/Lilly; European Diabetes Research Program).