Localisation of the relaxin-family peptide 3 receptor to enteroendocrine cells of the intestine in RXFP3-Cre/tdTomato mice

Linda J Fothergill; Mitchell T Ringuet; Lara M Voglsanger; Wesley J N Plange; Leigh C Walker; Leni R Rivera; Andrew J Lawrence; Andrew L Gundlach; Shanti Diwakarla; John B Furness; Craig M Smith

doi:10.1016/j.bcp.2024.116714

Localisation of the relaxin-family peptide 3 receptor to enteroendocrine cells of the intestine in RXFP3-Cre/tdTomato mice

Biochem Pharmacol. 2024 Dec 13:232:116714. doi: 10.1016/j.bcp.2024.116714. Online ahead of print.

Affiliations

¹ The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia; Department of Anatomy and Physiology, The University of Melbourne, Victoria 3010, Australia; Immunology Division, The Walter and Eliza Hall Institute, Victoria 3052, Australia. Electronic address: fothergill.l@wehi.edu.au.
² Department of Microbiology and Immunology, The University of Melbourne, Victoria 3010, Australia.
³ Faculty of Health, School of Medicine, Institute for Mental and Physical Health and Clinical Translation (IMPACT), Deakin University, Waurn Ponds, Victoria 3216, Australia.
⁴ The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia.
⁵ The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Victoria 3010, Australia; Department of Anatomy and Physiology, The University of Melbourne, Victoria 3010, Australia.

PMID: 39675586
DOI: 10.1016/j.bcp.2024.116714

Abstract

The relaxin-family peptide 3 receptor (RXFP3) and its native ligand, relaxin-3, are expressed in specific populations of brain neurons, and research on this system has focused on its role in the central nervous system. However, some studies have indicated that relaxin-3 and RXFP3 are also expressed in peripheral organs, including the gut. In this study, we characterised the identity of RXFP3-expressing cells in the gastrointestinal tract, using RXFP3-Cre/tdTomato reporter mice. We identified RXFP3-tdTomato expression in neurons throughout the small and large intestine, in cells in the lamina propria of the colon, and in enteroendocrine cells in the small intestine. We characterised the frequency and phenotype of the RXFP3-tdTomato + enteroendocrine cells in both the duodenum and distal ileum and discovered that the reporter was expressed in populations of cells that co-express 5-hydroxytryptamine (5-HT), cholecystokinin (CCK), secretin, peptide YY (PYY), oxyntomodulin, neurotensin, ghrelin, or glucose-dependent insulinotropic polypeptide (GIP). Faithful co-expression of Cre and RXFP3 mRNA was confirmed in RXFP3-Cre mice using multiplex, fluorescence in situ hybridisation (via RNAscope™). Our results indicate that RXFP3 is expressed by the LIN, X, K, Onecut3, and EC enteroendocrine cell types. In light of the key physiological roles of these cells, this study highlights the potential for relaxin-3 signalling via RXFP3 in enteroendocrine cells to modulate digestion, metabolism, food intake, and inflammatory processes.

Keywords: Enteroendocrine cells; Gut hormones; Incretins; RXFP3; Relaxin-3; Serotonin.