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 3

The dsRNA response during gastric metaplasia is independent of IFNAR1 signaling.

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The dsRNA response during gastric metaplasia is independent of IFNAR1 si...
(A) RT-PCR of Ifnar1 amplicons from gastric corpus tissue for wild-type (Ifnar1+/+) and age-matched Ifnar1–/– mice. Each lane represents an individual mouse. Gapdh, loading control. (B) Gastroids from wild-type or Ifnar1–/– mice were treated with PBS or IFN-β (100 U/mL) for 24 hours and lysates probed with the indicated antibodies. (C) Representative gastric corpus sections of wild-type or Ifnar1–/– mice treated with vehicle or high-dose tamoxifen (HD-Tam). Right panels highlight representative glands under each treatment. Arrowheads highlight metaplastic glands. Scale bars, 250 μm (left panels), 20 μm (right panels). (D) Metaplastic changes in wild-type and Ifnar1–/– mice infected with H. pylori (Hp) for 2 weeks. Scale bars, 20 μm. (C and D) Images are representative of 3 mice per experimental treatment. (E) Relative gene expression profiles between wild-type and Ifnar1–/– mice treated with HD-Tam for 48 hours. Three mice were used per genotype. (F) Fold change expression, relative to vehicle-treated, genotype-matched mice, of various dsRNA transcripts was determined by qRT-PCR. Each data point represents gastric corpus tissue from an individual mouse across 2 independent experiments. Means (±SEM) are shown. P values were determined using Student’s t test. No significant differences (P > 0.05) were observed between wild-type and Ifnar1–/– mice for all the transcripts investigated. #, not detected. (G) Gastric corpus tissue from Ifnar1–/– mice following HD-Tam treatment. Each lane shows a representative mouse from 3 mice per time point. (H) Representative confocal images of Ifnar1–/– gastric corpus gland bases, following the indicated HD-Tam treatment times, show the accumulation of dsRNA (red). Chief cells are highlighted in green. Images are representative of 3 separate mice per time point. Scale bars, 5 μm.