NADPH Oxidase 1 Modulates WNT and NOTCH1 Signaling To Control the Fate of Proliferative Progenitor Cells in the Colon

Abstract

The homeostatic self-renewal of the colonic epithelium requires coordinated regulation of the canonical Wnt/β-catenin and Notch signaling pathways to control proliferation and lineage commitment of multipotent stem cells. However, the molecular mechanisms by which the Wnt/β-catenin and Notch1 pathways interplay in controlling cell proliferation and fate in the colon are poorly understood. Here we show that NADPH oxidase 1 (NOX1), a reactive oxygen species (ROS)-producing oxidase that is highly expressed in colonic epithelial cells, is a pivotal determinant of cell proliferation and fate that integrates Wnt/β-catenin and Notch1 signals. NOX1-deficient mice reveal a massive conversion of progenitor cells into postmitotic goblet cells at the cost of colonocytes due to the concerted repression of phosphatidylinositol 3-kinase (PI3K)/AKT/Wnt/β-catenin and Notch1 signaling. This conversion correlates with the following: (i) the redox-dependent activation of the dual phosphatase PTEN, causing the inactivation of the Wnt pathway effector β-catenin, and (ii) the downregulation of Notch1 signaling that provokes derepression of mouse atonal homolog 1 (Math1) expression. We conclude that NOX1 controls the balance between goblet and absorptive cell types in the colon by coordinately modulating PI3K/AKT/Wnt/β-catenin and Notch1 signaling. This finding provides the molecular basis for the role of NOX1 in cell proliferation and postmitotic differentiation.

We thank R. Kopan (Washington University), F. Logeat, and D. Ndiaye (Institut Pasteur, Paris, France) for the Notch construct and antibodies against Notch1 and NICD; S. H. E. Moore (CRB3 INSERM, Paris, France) for discussion and critical reading of the manuscript; T. L. Leto (NIH, Bethesda, MD) for the gift of the pcDNA3-NOX1 construct; C. Bonhomme (Strasbourg, France) for the gift of Cdx1 antibody; and S. Benadda and O. Thibaudeau (IFR02, Paris, France) for technical help.

Financial support was from the Institut National de la Santé et de la Recherche Médicale (INSERM), Association François Aupetit (AFA) (to E.O.D.), Assistance Publique-Hôpitaux de Paris (AP-HP) (Interface Fellowship to E.O.D.), Société Nationale Française de Gastro-Entérologie (SNFGE), Association Française pour l'Étude du Foie (AFEF), and Programme National de Recherche en Hépato-Gastroentérologie (PNRHGE) (to X.T. and E.O.D.). N.C. was supported by a Ph.D. student's grant from the AFA. S.B.M. was supported by a Ph.D. student's grant from the Ligue Nationale contre le Cancer. C.G. was supported by a postdoctoral fellowship from EASL. X.T. was supported by a doctoral position from INSERM (poste d'accueil).