Or51e2, an olfactory receptor belonging to the class A G protein-coupled receptors (GPCRs), is crucial for our sense of smell as it participates in the combinatorial activation with other odorant receptors to detect chemically diverse odour molecules. It has also been implicated in non-olfactory physiological processes. For instance, it activates ERK1/2 through the Golgi-localized Gβγ-PI3Kγ-ARF1 pathway in prostate cancer cells, and is involved in pathways related to acetate-mediated calcitonin secretion in parafollicular C-cells [1,2].

In the study of colitis, Olfr-78 (the mouse counterpart of human OR51E2) was found to be highly expressed in the colon but downregulated in DSS-and TNBS-induced colitis models. Olfr-78 knockout mice showed increased expression of IL-1β and inflammatory signs in the colon compared to control mice, suggesting a role of Or51e2 in modulating intestinal inflammation [3].

In conclusion, Or51e2 plays essential roles in both olfactory and non-olfactory biological processes. Its functions in disease conditions such as prostate cancer, medullary thyroid cancer, and colitis have been revealed through in vivo studies including gene knockout mouse models. These studies contribute to understanding the underlying mechanisms of these diseases and potentially offer new therapeutic targets.