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Updated: Sep 24, 2025

Reverse Yeast Two-hybrid System to Identify Mammalian Nuclear Receptor Residues that Interact with Ligands and/or Antagonists
Published on: November 15, 2013
Reviewing the physiological roles of the novel hormone-receptor pair INSL5-RXFP4: a protective energy sensor?
Drake Hechter1, Brett Vahkal2,3, Tiana Tiede2
1Department of Food and Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
Abstract:
There is no common consensus on the physiological role of insulin-like peptide 5 (INSL5) and its cognate receptor, relaxin family peptide receptor 4 (RXFP4). The experimental data for INSL5-RXFP4 expression and function point to a potential role of the peptide hormone and receptor pair in linking energy availability, homeostasis, and inflammation. In this review, we summarize studies on the INSL5-RXFP4 system and propose that the current findings from diverse experimental settings point broadly to a role as a protective energy sensor (PES). Specifically, we review the evidence that (1) INSL5-RXFP4 could regulate immune response by decreasing the production of proinflammatory cytokines and may be involved in the stress response via the HPA axis; (2) INSL5-RXFP4 may signal through sensory neurons on the vagus nerve, transmitting signals to the CNS; and (3) INSL5-RXFP4 could have local autocrine/paracrine roles within the intestinal tract and immune cells. Further investigation and clarification of these proposed roles of INSL5-RXFP4 may prove a greater physiological relevance for the pair and add to existing evidence of INSL5-RXFP4 role as a PES.
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