Research Paper|Volume 11, Issue 2|pp 386—400

Loss of GPR109A/HCAR2 induces aging-associated hepatic steatosis

Ravirajsinh N. Jadeja^1,², Malita A. Jones¹, Ollya Fromal¹, Folami L. Powell^1,^2,³, Sandeep Khurana⁴, Nagendra Singh^1,⁵, Pamela M. Martin^1,^2,^5,⁶

¹Department of Biochemistry and Molecular Biology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
²James and Jean Culver Vision Discovery Institute, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
³Education Innovation Institute, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
⁴Division of Gastroenterology, Hepatology and Nutrition and Weight Management, Geisinger Medical Center, Danville, PA 17822, USA
⁵Georgia Cancer Center, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
⁶Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA

Received: November 21, 2018Accepted: December 20, 2018Published: January 18, 2019

https://doi.org/10.18632/aging.101743

Copyright: © 2019 Jadeja et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

GPR109A agonists have been used for the treatment of obesity however, the role of GPR109A in regulating aging-associated alterations in lipid metabolism is unknown. In this study we used Gpr109a^-/- mice to investigate the effect of aging in the regulation of lipid accumulation. We observed that in mouse and human livers, in addition to Kupffer cells, GPR109A is expressed in hepatocytes. Over 12 months, compared to wild type (WT), Gpr109a^-/- mice gained significantly more weight. Food intake and levels of serum lipids were similar among both groups. Compared to age-matched WT mice, 12-months old Gpr109a^-/- mice had significantly increased liver weight, hepatic steatosis and serum markers of liver injury. The fatty liver phenotype in Gpr109a^-/- mice was associated with increased hepatic expression of lipogenesis genes and decreased expression of lipolysis genes. Gpr109a^-/- mice had significantly increased fat tissues, which was associated with significant increase in adipocyte diameter and surface area. Adipose tissue from Gpr109a^-/- mice had increased expression of lipogenesis genes; however, expression of lipolytic genes was similar in both groups. Collectively, these results indicate that during aging, GPR109A modulates de novo lipid accumulation in liver and adipose tissue, and its dysregulation can lead to age-associated obesity and hepatic steatosis.