Tracheal Basal cells: a facultative progenitor cell pool.
Analysis of lineage relationships in the naphthalene-injured tracheal epithelium demonstrated that two multipotential keratin 14-expressing cells (K14ECs) function as progenitors for Clara and ciliated cells. These K14EC were distinguished by their self-renewal capacity and were hypothesized to reside at the stem and transit amplifying tiers of a tissue-specific stem cell hierarchy. In this study, we used gene expression and histomorphometric analysis of the steady-state and naphthalene-injured trachea to evaluate the predictions of this model. We found that the steady-state tracheal epithelium is maintained by two progenitor cell pools, secretory and basal cells, and the latter progenitor pool is further divided into two subsets, keratin 14-negative and -positive. After naphthalene-mediated depletion of the secretory and ciliated cell types, the two basal cell pools coordinate to restore the epithelium. Both basal cell types up-regulate keratin 14 and generate a broadly distributed, abundant, and highly mitotic cell pool. Furthermore, basal cell proliferation is associated with generation of differentiated Clara and ciliated cells. The uniform distribution of basal cell progenitors and of their differentiated progeny leads us to propose that the hierarchical organization of tracheal reparative cells be revised to include a facultative basal cell progenitor pool.
Cole
Brook B
BB
Department of Pediatrics, Division of Cell Biology, National Jewish Health, Denver, Colorado, USA.
Smith
Russell W
RW
Jenkins
Kimberly M
KM
Graham
Brian B
BB
Reynolds
Paul R
PR
Reynolds
Susan D
SD
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002467:Cell Nucleus / Q000648:ultrastructure; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D053547:Keratin-14 / Q000378:metabolism; D008171:Lung Diseases / Q000139:chemically induced / Q000473:pathology; D051379:Mice; D009281:Naphthalenes / Q000494:pharmacology; D010641:Phenotype; D012038:Regeneration; D013234:Stem Cells / Q000166:cytology / Q000502:physiology*; D014132:Trachea / Q000166:cytology* / Q000187:drug effects / Q000473:pathology
D053547:Keratin-14; C507446:Krt14 protein, mouse; D009281:Naphthalenes; C031721:naphthalene