Emergence of brown adipocytes in white fat in mice is under genetic control. Effects on body weight and adiposity.

TLDR

UCP1 mRNA expression in mouse fat varies regionally between A/J and C57BL/6J strains after adrenergic stimulation. The study uses this genetic variation to identify genes that control brown adipocyte induction in white fat. In AXB recombinant strains, Ucp1 mRNA varied up to 130‑fold, increasing brown adipocytes in white fat; high inducibility did not affect weight gain on a high‑fat diet but was linked to weight loss with beta3‑adrenergic agonist treatment.

Abstract

The mRNA levels for the mitochondrial uncoupling protein (UCP1) in fat tissues of A/J and C57BL/6J inbred strains of mice varied in a regional-specific manner after stimulation of adrenergic signaling by cold exposure or treatment with a beta3-adrenergic agonist. While the differences between strains were minimal in interscapular brown fat, large differences occurred in white fat tissues, particularly in retroperitoneal fat. Among the AXB recombinant inbred strains, the Ucp1 mRNA levels varied up to 130-fold. This large induction at the mRNA level was accompanied by a corresponding increase in brown adipocytes as revealed by immunohistology with anti-UCP1 antibodies. A high capacity to induce brown fat in areas of traditional white fat had no impact on the ability to gain weight in response to high fat and sucrose diets, but did correlate with the loss of weight in response to treatment with a beta3-adrenergic agonist (CL 316,243). This genetic variation in mice provides an experimental approach to identify genes controlling the induction of brown adipocytes in white fat tissues.