title: The human airway epithelial basal cell transcriptome.
abstract: BACKGROUND
  The human airway epithelium consists of 4 major cell types: ciliated, secretory, columnar and basal cells. During natural turnover and in response to injury, the airway basal cells function as stem/progenitor cells for the other airway cell types. The objective of this study is to better understand human airway epithelial basal cell biology by defining the gene expression signature of this cell population.
  
  
  RESULTS
  Bronchial brushing was used to obtain airway epithelium from healthy nonsmokers. Microarrays were used to assess the transcriptome of basal cells purified from the airway epithelium in comparison to the transcriptome of the differentiated airway epithelium. This analysis identified the "human airway basal cell signature" as 1,161 unique genes with >5-fold higher expression level in basal cells compared to differentiated epithelium. The basal cell signature was suppressed when the basal cells differentiated into a ciliated airway epithelium in vitro. The basal cell signature displayed overlap with genes expressed in basal-like cells from other human tissues and with that of murine airway basal cells. Consistent with self-modulation as well as signaling to other airway cell types, the human airway basal cell signature was characterized by genes encoding extracellular matrix components, growth factors and growth factor receptors, including genes related to the EGF and VEGF pathways. Interestingly, while the basal cell signature overlaps that of basal-like cells of other organs, the human airway basal cell signature has features not previously associated with this cell type, including a unique pattern of genes encoding extracellular matrix components, G protein-coupled receptors, neuroactive ligands and receptors, and ion channels.
  
  
  CONCLUSIONS
  The human airway epithelial basal cell signature identified in the present study provides novel insights into the molecular phenotype and biology of the stem/progenitor cells of the human airway epithelium.
authors.affiliation: Department of Genetic Medicine, Weill Cornell Medical College, New York, New York, United States of America.
authors.forename: Neil R
authors.initials: NR
authors.lastname: Hackett
authors.forename: Renat
authors.initials: R
authors.lastname: Shaykhiev
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Walters
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Rachel K
authors.initials: RK
authors.lastname: Zwick
authors.forename: Barbara
authors.initials: B
authors.lastname: Ferris
authors.forename: Bradley
authors.initials: B
authors.lastname: Witover
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Salit
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Crystal
mesh_terms: D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism*; D020869:Gene Expression Profiling / Q000379:methods*; D006801:Humans; D012137:Respiratory System / Q000166:cytology*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology