Loss of GIPR in LEPR cells impairs glucose control by GIP and GIP:GLP-1 co-agonism without affecting body weight and food intake in mice

🥉 Top 5% JournalMar 16, 2024Molecular metabolism

Loss of GIP receptor in leptin receptor cells reduces glucose control by GIP and GIP-GLP-1 combination without changing body weight or food intake in mice

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Abstract

GIPR signaling in leptin receptor-expressing cells does not affect body weight or food intake in diet-induced obesity mice.

GIPR and leptin receptors show strong co-expression in the pancreas, but not in the hypothalamus or hindbrain.
Mice lacking Gipr in leptin receptor-expressing cells exhibit similar body weight and food intake as wildtype mice under diet-induced obesity conditions.
Both acyl-GIP and the GIPR:GLP-1R co-agonist MAR709 effectively reduce body weight and food intake in the absence of GIPR signaling in leptin receptor cells.
The enhanced glycemic effect of GIPR:GLP-1R co-agonism compared to single GLP-1R agonism is lost in leptin receptor-GIPR knockout mice.

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OBJECTIVE: The glucose-dependent insulinotropic polypeptide (GIP) decreases body weight via central GIP receptor (GIPR) signaling, but the underlying mechanisms remain largely unknown. Here, we assessed whether GIP regulates body weight and glucose control via GIPR signaling in cells that express the leptin receptor (Lepr).

METHODS: Hypothalamic, hindbrain, and pancreatic co-expression of Gipr and Lepr was assessed using single cell RNAseq analysis. Mice with deletion of Gipr in Lepr cells were generated and metabolically characterized for alterations in diet-induced obesity (DIO), glucose control and leptin sensitivity. Long-acting single- and dual-agonists at GIPR and GLP-1R were further used to assess drug effects on energy and glucose metabolism in DIO wildtype (WT) and Lepr-Gipr knock-out (KO) mice.

RESULTS: Gipr and Lepr show strong co-expression in the pancreas, but not in the hypothalamus and hindbrain. DIO Lepr-Gipr KO mice are indistinguishable from WT controls related to body weight, food intake and diet-induced leptin resistance. Acyl-GIP and the GIPR:GLP-1R co-agonist MAR709 remain fully efficacious to decrease body weight and food intake in DIO Lepr-Gipr KO mice. Consistent with the demonstration that Gipr and Lepr highly co-localize in the endocrine pancreas, including the β-cells, we find the superior glycemic effect of GIPR:GLP-1R co-agonism over single GLP-1R agonism to vanish in Lepr-Gipr KO mice.

CONCLUSIONS: GIPR signaling in cells/neurons that express the leptin receptor is not implicated in the control of body weight or food intake, but is of crucial importance for the superior glycemic effects of GIPR:GLP-1R co-agonism relative to single GLP-1R agonism.

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