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 January 17, 2017
Citation Information: J Clin Invest. 2017;127(2):593-607. https://doi.org/10.1172/JCI87588.
View: Text | PDF
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

×

Figure 4

Decreased Gpr182 leads to hyperproliferation during the regeneration phase after irradiation-induced injury.

Options: View larger image (or click on image) Download as PowerPoint
Decreased Gpr182 leads to hyperproliferation during the regeneration pha...
Adult Gpr182+/+ (purple) and Gpr182lacZ/lacZ (green) mice were challenged with a single 14-Gy dose of radiation (IRR) to the abdomen. (A) BW changes (percentage of pre-IRR weight) of Gpr182+/+ and Gpr182lacZ/lacZ mice for 5 days following IRR compared with BW of non-IRR control mice. Small intestine length (B) and regenerating crypt depth (C) in IRR-treated Gpr182+/+ and Gpr182lacZ/lacZ animals. (D) Whole-mount X-gal–stained small intestine from non-IRR–treated Gpr182lacZ/lacZ and IRR-treated Gpr182lacZ/lacZ animals 5 days after IRR. (E) Relative expression of Gpr182 and ISC markers Lgr5, Bmi1, and Lrig1 in whole jejunum from Gpr182+/+ IRR, Gpr182lacZ/lacZ IRR, and non-IRR Gpr182+/+ animals. Expression was normalized to non-IRR Gpr182+/+, Gapdh, and 18S. (F) Representative images and (G) EdU quantification of intestinal proliferation among IRR Gpr182+/+ and Gpr182lacZ/lacZ animals. (H) 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 regenerating crypts. n = 10–60 open crypts per region per mouse. Biological replicates: n = 4–5 mice per genotype. Scale bars: 5 mm (D) and 100 μm (F). *P < 0.05, **P < 0.01, and ***P < 0.001, by 2-tailed Student’s t test (B, C, and G), 1-way ANOVA with Tukey’s multiple comparisons test (E), or Mann-Whitney t test of the AUC (H).