title: Analysis of Notch signaling-dependent gene expression in developing airways reveals diversity of Clara cells.
abstract: Clara cells (CCs) are a morphologically and operationally heterogeneous population of Secretoglobin Scgb1a1-expressing secretory cells that are crucial for airway homeostasis and post-injury repair. Analysis of the extent and origin of CC diversity are limited by knowledge of genes expressed in these cells and their precursors. To identify novel putative markers of CCs and explore the origins of CC diversity, we characterized global changes in gene expression in embryonic lungs in which CCs do not form due to conditional disruption of Notch signaling (Rbpjk(CNULL)). Microarray profiling, Real Time PCR (qRT-PCR), and RNA in situ hybridization (ISH) identified eleven genes downregulated in the E18.5 airways of Rbpjk(cnull) compared to controls, nearly half not previously known to mark CCs. ISH revealed that several genes had overlapping but distinct domains of expression of in the normal developing lung (E18.5). Notably, Reg3g, Chad, Gabrp and Lrrc26 were enriched in proximal airways, Hp in the distal airways and Upk3a in clusters of cells surrounding Neuroepithelial Bodies (NEBs). Seven of the eleven genes, including Reg3g, Hp, and Upk3a, were expressed in the adult lung in CCs in a pattern similar to that observed in the developing airways. qRT-PCR-based analysis of gene expression of CCs isolated from different airway regions of B1-EGFP reporter mice corroborated the spatial enrichment in gene expression observed by ISH. Our study identifies candidate markers for CC-precursors and CCs and supports the idea that the diversification of the CC phenotype occurs already during embryonic development.
authors.affiliation: Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Arjun
authors.initials: A
authors.lastname: Guha
authors.affiliation: Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Michelle
authors.initials: M
authors.lastname: Vasconcelos
authors.affiliation: Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America ; Pulmonary and Critical Care Unit, Departments of Internal Medicine and Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, United States of America.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhao
authors.affiliation: Boston University Clinical and Translational Science Institute, Boston, Massachusetts, United States of America.
authors.forename: Adam C
authors.initials: AC
authors.lastname: Gower
authors.affiliation: Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America ; Pulmonary and Critical Care Unit, Departments of Internal Medicine and Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, United States of America.
authors.forename: Jayaraj
authors.initials: J
authors.lastname: Rajagopal
authors.affiliation: Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Wellington V
authors.initials: WV
authors.lastname: Cardoso
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D017403:In Situ Hybridization; D008168:Lung / Q000196:embryology* / Q000378:metabolism*; D051379:Mice; D046228:Microarray Analysis; D060888:Real-Time Polymerase Chain Reaction; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D015415:Biomarkers; D051880:Receptors, Notch