Orphan Gpr182 suppresses ERK-mediated intestinal proliferation during regeneration and adenoma formation
Daniel O. Kechele, … , P. Kay Lund, Kathleen M. Caron
Daniel O. Kechele, … , P. Kay Lund, Kathleen M. Caron
Published February 1, 2017; First published January 17, 2017
Citation Information: J Clin Invest. 2017;127(2):593-607. https://doi.org/10.1172/JCI87588.
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Research Article Gastroenterology

Orphan Gpr182 suppresses ERK-mediated intestinal proliferation during regeneration and adenoma formation

Abstract

Orphan GPCRs provide an opportunity to identify potential pharmacological targets, yet their expression patterns and physiological functions remain challenging to elucidate. Here, we have used a genetically engineered knockin reporter mouse to map the expression pattern of the Gpr182 during development and adulthood. We observed that Gpr182 is expressed at the crypt base throughout the small intestine, where it is enriched in crypt base columnar stem cells, one of the most active stem cell populations in the body. Gpr182 knockdown had no effect on homeostatic intestinal proliferation in vivo, but led to marked increases in proliferation during intestinal regeneration following irradiation-induced injury. In the ApcMin mouse model, which forms spontaneous intestinal adenomas, reductions in Gpr182 led to more adenomas and decreased survival. Loss of Gpr182 enhanced organoid growth efficiency ex vivo in an EGF-dependent manner. Gpr182 reduction led to increased activation of ERK1/2 in basal and challenge models, demonstrating a potential role for this orphan GPCR in regulating the proliferative capacity of the intestine. Importantly, GPR182 expression was profoundly reduced in numerous human carcinomas, including colon adenocarcinoma. Together, these results implicate Gpr182 as a negative regulator of intestinal MAPK signaling–induced proliferation, particularly during regeneration and adenoma formation.

Authors

Daniel O. Kechele, R. Eric Blue, Bailey Zwarycz, Scott T. Espenschied, Amanda T. Mah, Marni B. Siegel, Charles M. Perou, Shengli Ding, Scott T. Magness, P. Kay Lund, Kathleen M. Caron

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Figure 3

Reduced Gpr182 does not alter basal proliferation in vivo.

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Reduced Gpr182 does not alter basal proliferation in vivo. (A) Length of...
(A) Length of small intestines from adult Gpr182+/+, Gpr182lacZ/lacZ, and Gpr182Δ/Δ CMV-Cre mice. (B) Morphometric quantification of crypt density and (C) histological quantification of crypt depth among Gpr182 genotypes. (D) Representative images and (E) EdU incorporation quantification of intestinal proliferation in Gpr182+/+ and Gpr182lacZ/lacZ animals. (F) Analysis of the cellular position of EdU+ cells along the crypt axis expressed as a percentage of the total number of cells in that position in all crypts. n = 20–60 open crypts per region per mouse. The Gpr182 zone (green gradient) is the relative cellular position of β-gal+ cells along the crypt axis. (G) Relative expression of Ccnd1, Lgr5, Olfm4, hairy and enhancer of split 1 (Hes1), chromogranin A (Chga), and Lysozyme (Lyz2) in whole jejunum from Gpr182+/+ CMV-Cre and Gpr182Δ/Δ CMV-Cre mice. Expression was normalized to Gpr182+/+ and 18S. Biological replicates: n = 3–5 mice per genotype. Scale bars: 100 μm. Significance was determined by either 1-way ANOVA with Tukey’s multiple comparisons test.