β-Catenin is not necessary for maintenance or repair of the bronchiolar epithelium

AC Zemke, RM Teisanu, A Giangreco… - American journal of …, 2009 - atsjournals.org
AC Zemke, RM Teisanu, A Giangreco, JA Drake, BL Brockway, SD Reynolds, BR Stripp
American journal of respiratory cell and molecular biology, 2009atsjournals.org
Signaling by Wnt/β-catenin regulates self-renewal of tissue stem cells in the gut and, when
activated in the embryonic bronchiolar epithelium, leads to stem cell expansion. We have
used transgenic and cell type–specific knockout strategies to determine roles for β-catenin–
regulated gene expression in normal maintenance and repair of the bronchiolar epithelium.
Analysis of TOPGal transgene activity detected β-catenin signaling in the steady-state and
repairing bronchiolar epithelium. However, the broad distribution and phenotype of …
Signaling by Wnt/β-catenin regulates self-renewal of tissue stem cells in the gut and, when activated in the embryonic bronchiolar epithelium, leads to stem cell expansion. We have used transgenic and cell type–specific knockout strategies to determine roles for β-catenin–regulated gene expression in normal maintenance and repair of the bronchiolar epithelium. Analysis of TOPGal transgene activity detected β-catenin signaling in the steady-state and repairing bronchiolar epithelium. However, the broad distribution and phenotype of signaling cells precluded establishment of a clear role for β-catenin in the normal or repairing state. Necessity of β-catenin signaling was tested through Cre-mediated deletion of Catnb exons 2–6 in airway epithelial cells. Functional knockout of β-catenin had no impact on expression of Clara cell differentiation markers, mitotic index, or sensitivity of these cells to the Clara cell–specific toxicant, naphthalene. Repair of the naphthalene-injured airway proceeded with establishment of focal regions of β-catenin–null epithelium. The size of regenerative epithelial units, mitotic index, and restoration of the ciliated cell population did not vary between wild-type and genetically modified mice. Thus, β-catenin was not necessary for maintenance or efficient repair of the bronchiolar epithelium.
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