Regulation of the double-stranded RNA response through ADAR1 licenses metaplastic reprogramming in gastric epithelium
José B. Sáenz, Nancy Vargas, Charles J. Cho, Jason C. Mills
José B. Sáenz, Nancy Vargas, Charles J. Cho, Jason C. Mills
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Research Article Cell biology Gastroenterology

Regulation of the double-stranded RNA response through ADAR1 licenses metaplastic reprogramming in gastric epithelium

Abstract

Cells recognize both foreign and host-derived double-stranded RNA (dsRNA) via a signaling pathway that is usually studied in the context of viral infection. It has become increasingly clear that the sensing and handling of endogenous dsRNA is also critical for cellular differentiation and development. The adenosine RNA deaminase, ADAR1, has been implicated as a central regulator of the dsRNA response, but how regulation of the dsRNA response might mediate cell fate during injury and whether such signaling is cell intrinsic remain unclear. Here, we show that the ADAR1-mediated response to dsRNA was dramatically induced in 2 distinct injury models of gastric metaplasia. Mouse organoid and in vivo genetic models showed that ADAR1 coordinated a cell-intrinsic, epithelium-autonomous, and interferon signaling–independent dsRNA response. In addition, dsRNA accumulated within a differentiated epithelial population (chief cells) in mouse and human stomachs as these cells reprogrammed to a proliferative, reparative (metaplastic) state. Finally, chief cells required ADAR1 to reenter the cell cycle during metaplasia. Thus, cell-intrinsic ADAR1 signaling is critical for the induction of metaplasia. Because metaplasia increases cancer risk, these findings support roles for ADAR1 and the response to dsRNA in oncogenesis.

Authors

José B. Sáenz, Nancy Vargas, Charles J. Cho, Jason C. Mills

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Figure 6

Loss of Adar1 from chief cells does not affect metaplastic gene expression but limits cellular proliferation following HD-Tam treatment.

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Loss of Adar1 from chief cells does not affect metaplastic gene expressi...
(A) Adar1fl/fl Mist1Cre-ERT/+ ROSA26LSLTdTomato mice were treated with either vehicle or low-dose tamoxifen (LD-Tam) for 7 days to induce Cre-mediated deletion of Adar1 from chief cells. Four days later, mice were treated with either vehicle or high-dose tamoxifen (HD-Tam) for an additional 2 days to induce metaplasia, then euthanized 1 day after the last injection. (B) Metaplastic changes in mice with Adar1-sufficient (middle) and -deficient (bottom) chief cells after HD-Tam injury. Arrowheads point to metaplastic glands. Chief cells are labeled with GIF (red), neck cells with GSII (green). Scale bars, 50 μm (left panels), 10 μm (right panels). (C) Adar1-deficient chief cells show decreased Ki-67 staining following HD-Tam treatment (bottom), compared with HD-Tam–treated, Adar1-sufficient chief cells (top). The gland base and neck regions are indicated by brackets. For B and C, representative gland bases are shown in right panels, with TdTomato signal demonstrating Mist1Cre-ERT lineage tracing in chief cells. For B and C, images are representative of 3–4 mice per experimental condition. (D) The number of Ki-67–positive cells per gland base was quantified for each experimental setup. Each data point represents the mean number of Ki-67–positive cells per gland across randomly selected fields from an individual mouse, and the mean (±SD) of those data points is indicated. P values were determined by 1-way ANOVA using Tukey’s multiple comparisons test. (E) Gene set enrichment analysis demonstrates molecular pathways enriched in gastric corpus tissue from Adar1-sufficient (black) and -deficient (gray) chief cells after 48 hours of HD-Tam injury. Adjusted P values were determined using g:Profiler (68). Microarray data were obtained from 3 individual mice per experimental condition. GIF, gastric intrinsic factor; GSII, Griffonia simplicifolia lectin.