Objective Multiple genome-wide association studies (GWAS) have identified SNPs in the 8q24 locus near TRIB1 that are significantly associated with plasma lipids and other markers of cardiometabolic health, and prior studies have revealed the roles of hepatic and myeloid Trib1 in plasma lipid regulation and atherosclerosis. The same 8q24 SNPs are additionally associated with plasma adiponectin levels in humans, implicating TRIB1 in adipocyte biology. Here, we hypothesize that TRIB1 in adipose tissue regulates plasma adiponectin, lipids, and metabolic health. Methods We investigate the metabolic phenotype of adipocyte-specific Trib1 knockout mice (Trib1_ASKO) fed on chow and high-fat diet (HFD). Through secretomics of adipose tissue explants and RNA-seq of adipocytes and livers from these mice, we further investigate the mechanism of TRIB1 in adipose tissue. Results Trib1_ASKO mice have an improved metabolic phenotype with increased plasma adiponectin levels, improved glucose tolerance, and decreased plasma lipids. Trib1_ASKO adipocytes have increased adiponectin production and secretion independent of the known TRIB1 function of regulating proteasomal degradation. RNA-seq analysis of adipocytes and livers from Trib1_ASKO mice indicates that alterations in adipocyte function underlie the observed plasma lipid changes. Adipose tissue explant secretomics further reveals that Trib1_ASKO adipose tissue has decreased ANGPTL4 production, and we demonstrate an accompanying increase in the lipoprotein lipase (LPL) activity that likely underlies the triglyceride phenotype. Conclusions This study shows that adipocyte Trib1 regulates multiple aspects of metabolic health, confirming previously observed genetic associations in humans and shedding light on the further mechanisms by which TRIB1 regulates plasma lipids and metabolic health.

Multiple GWAS have identified SNPs in the 8q24 locus near the TRIB1 gene that significantly associate with plasma lipids and coronary artery disease. While subsequent studies have uncovered roles for hepatic and myeloid Trib1 in contributing to either plasma lipids or atherosclerosis, the causal tissue for these GWAS associations remains unclear. The same 8q24 SNPs significantly associate with plasma adiponectin levels in humans as well, suggesting a role for TRIB1 in adipose tissue. Here, we report that adipocyte-specific Trib1 knockout mice (Trib1_ASKO) have increased plasma adiponectin levels and decreased plasma cholesterol and triglycerides. We demonstrate that loss of Trib1 increases adipocyte production and secretion of adiponectin independent of the known TRIB1 function of regulating proteasomal degradation. RNA-seq analysis of adipocytes and livers from Trib1_ASKO mice suggests that alterations in adipocyte function underlie the plasma lipid changes observed in these mice. Secretomics and RNA-seq analysis revealed that Trib1_ASKO mice have increased production of Lpl and decreased production of Angptl4 in adipose tissue, and fluorescent substrate assays confirm an increase in adipose tissue Lpl activity, which likely underlies the observed triglyceride phenotype. In summary, we demonstrate here a novel role for adipocyte Trib1 in regulating plasma adiponectin, total cholesterol, and triglycerides in mice, confirming previous genetic associations observed in humans and providing a novel avenue through which Trib1 regulates plasma lipids and coronary artery disease.