title: NOTCH1 is required for regeneration of Clara cells during repair of airway injury.
abstract: The airways of the mammalian lung are lined with highly specialized epithelial cell types that are the targets of airborne toxicants and injury. Notch signaling plays an important role in the ontogeny of airway epithelial cells, but its contributions to recruitment, expansion or differentiation of resident progenitor/stem cells, and repair and re-establishment of the normal composition of airway epithelium following injury have not been addressed. In this study, the role of a specific Notch receptor, Notch1, was investigated by targeted inactivation in the embryonic lung epithelium using the epithelial-specific Gata5-Cre driver line. Notch1-deficient mice are viable without discernible defects in pulmonary epithelial cell-fate determination and differentiation. However, in an experimental model of airway injury, activity of Notch1 is found to be required for normal repair of the airway epithelium. Absence of Notch1 reduced the ability of a population of cells distinguished by expression of PGP9.5, otherwise a marker of pulmonary neuroendocrine cells, which appears to serve as a reservoir for regeneration of Clara cells. Hairy/enhancer of split-5 (Hes5) and paired-box-containing gene 6 (Pax6) were found to be downstream targets of Notch1. Both Hes5 and Pax6 expressions were significantly increased in association with Clara cell regeneration in wild-type lungs. Ablation of Notch1 reduced Hes5 and Pax6 and inhibited airway epithelial repair. Thus, although dispensable in developmental ontogeny of airway epithelial cells, normal activity of Notch1 is required for repair of the airway epithelium. The signaling pathway by which Notch1 regulates the repair process includes stimulation of Hes5 and Pax6 gene expression.
authors.affiliation: Department of Pediatrics, Division of Neonatology, Will Rogers Institute Pulmonary Research Center, University of Southern California, Keck School of Medicine, Los Angeles, California, USA.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Xing
authors.forename: Aimin
authors.initials: A
authors.lastname: Li
authors.forename: Zea
authors.initials: Z
authors.lastname: Borok
authors.forename: Changgong
authors.initials: C
authors.lastname: Li
authors.forename: Parviz
authors.initials: P
authors.lastname: Minoo
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis / Q000235:genetics; D005136:Eye Proteins / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation / Q000235:genetics; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics; D055370:Lung Injury / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism*; D012038:Regeneration; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics; D020545:Respiratory Mucosa / Q000293:injuries / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction; D043222:Ubiquitin Thiolesterase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D051881:Receptor, Notch1; D012097:Repressor Proteins; D043222:Ubiquitin Thiolesterase; C489685:Hes5 protein, mouse; C497762:Notch1 protein, mouse; C000605732:Pax6 protein, mouse; C496976:Uchl1 protein, mouse