GIPR agonism mediates weight-independent insulin sensitization by tirzepatide in obese mice
Ricardo J. Samms, … , Kyle W. Sloop, William C. Roell
Ricardo J. Samms, … , Kyle W. Sloop, William C. Roell
Published May 18, 2021
Citation Information: J Clin Invest. 2021;131(12):e146353. https://doi.org/10.1172/JCI146353.
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Research Article Metabolism Therapeutics

GIPR agonism mediates weight-independent insulin sensitization by tirzepatide in obese mice

Abstract

Tirzepatide (LY3298176), a dual GIP and GLP-1 receptor (GLP-1R) agonist, delivered superior glycemic control and weight loss compared with GLP-1R agonism in patients with type 2 diabetes. However, the mechanism by which tirzepatide improves efficacy and how GIP receptor (GIPR) agonism contributes is not fully understood. Here, we show that tirzepatide is an effective insulin sensitizer, improving insulin sensitivity in obese mice to a greater extent than GLP-1R agonism. To determine whether GIPR agonism contributes, we compared the effect of tirzepatide in obese WT and Glp-1r–null mice. In the absence of GLP-1R–induced weight loss, tirzepatide improved insulin sensitivity by enhancing glucose disposal in white adipose tissue (WAT). In support of this, a long-acting GIPR agonist (LAGIPRA) was found to enhance insulin sensitivity by augmenting glucose disposal in WAT. Interestingly, the effect of tirzepatide and LAGIPRA on insulin sensitivity was associated with reduced branched-chain amino acids (BCAAs) and ketoacids in the circulation. Insulin sensitization was associated with upregulation of genes associated with the catabolism of glucose, lipid, and BCAAs in brown adipose tissue. Together, our studies show that tirzepatide improved insulin sensitivity in a weight-dependent and -independent manner. These results highlight how GIPR agonism contributes to the therapeutic profile of dual-receptor agonism, offering mechanistic insights into the clinical efficacy of tirzepatide.

Authors

Ricardo J. Samms, Michael E. Christe, Kyla A.L. Collins, Valentina Pirro, Brian A. Droz, Adrienne K. Holland, Jessica L. Friedrich, Samantha Wojnicki, Debra L. Konkol, Richard Cosgrove, Ellen P.S. Conceição Furber, Xiaoping Ruan, Libbey S. O’Farrell, Annie M. Long, Mridula Dogra, Jill A. Willency, Yanzhu Lin, Liyun Ding, Christine C. Cheng, Over Cabrera, Daniel A. Briere, Jorge Alsina-Fernandez, Ruth E. Gimeno, Julie S. Moyers, Tamer Coskun, Matthew P. Coghlan, Kyle W. Sloop, William C. Roell

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Figure 7

Tirzepatide and GIPR agonism induced BCAA catabolic gene expression in BAT in obese IR mice.

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Tirzepatide and GIPR agonism induced BCAA catabolic gene expression in B...
High-fat diet–fed obese insulin-resistant mice (C57BL/6J) were dosed once daily with vehicle (saline, n = 6), tirzepatide (TZP, n = 6), a long-acting glucose-dependent insulinotropic polypeptide receptor agonist (LAGIPRA, n = 6), or saline (pair fed, n = 6). Following 14 days of treatment, tissue samples were collected for metabolic and molecular analyses. (A) Venn diagram of differentially (up- and downregulated gene expression) expressed genes (FDR < 0.05). (B) Heatmap of RNA-Seq expression Z-scores computed for genes associated with the branched-chain amino acid (BCAA) pathway in brown adipose tissue (BAT). *P < 0.05 compared with vehicle and #P < 0.05 compared with pair fed. Statistical analyses was performed using 1-way ANOVA, followed by FDR correction, where appropriate.