Human Genetic Variation at rs10071329 Correlates with Adiposity-related Traits, Modulates PPARGC1B Expression, and Alters Brown Adipocyte Function

Abstract

Human genetic variation in PPARGC1B has been associated with adiposity, but the genetic variants that affect PPARGC1B expression have not been experimentally determined. Here, guided by previous observational data, we used CRISPR/Cas9 to scarlessly edit the alleles of the candidate causal genetic variant rs10071329 in a human brown adipocyte cell line (hBAs). Switching the rs10071329 genotype from A/A to G/G enhanced PPARGC1B expression throughout the adipogenic differentiation, identifying rs10071329 as a cis-eQTL. The higher PPARGC1B expression in G/G cells coincided with greater accumulation of triglycerides, and higher expression of mitochondria-encoded genes, but without significant effects on adipogenic marker expression. Furthermore, G/G cells had improved basal- and norepinephrine-stimulated mitochondrial respiration, possibly relating to enhanced mitochondrial gene expression. The G/G cells also exhibited increased norepinephrine-stimulated glycerol release, indicating improved lipolysis. Altogether, our results showed that rs10071329 is a cis-eQTL, with the G/G genotype conferring enhanced PPARGC1B expression, with consequent improved mitochondrial function and response to norepinephrine in brown adipocytes. This genetic variant, and as yet undetermined eQTLs, at PPARGC1B could prove useful in genotype-based precision medicine for obesity treatment.