Division of Pulmonary Biology in the Perinatal Institute , Cincinnati Children's Hospital Medical Center and the University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America.
PLoS One. 2009 Dec 14;4(12):e8248. doi: 10.1371/journal.pone.0008248.
The bronchioles of the murine lung are lined by a simple columnar epithelium composed of ciliated, Clara, and goblet cells that together mediate barrier function, mucociliary clearance and innate host defense, vital for pulmonary homeostasis. In the present work, we demonstrate that expression of Sox2 in Clara cells is required for the differentiation of ciliated, Clara, and goblet cells that line the bronchioles of the postnatal lung. The gene was selectively deleted in Clara cells utilizing Scgb1a1-Cre, causing the progressive loss of Sox2 in the bronchioles during perinatal and postnatal development. The rate of bronchiolar cell proliferation was decreased and associated with the formation of an undifferentiated, cuboidal-squamous epithelium lacking the expression of markers of Clara cells (Scgb1a1), ciliated cells (FoxJ1 and alpha-tubulin), and goblet cells (Spdef and Muc5AC). By adulthood, bronchiolar cell numbers were decreased and Sox2 was absent in extensive regions of the bronchiolar epithelium, at which time residual Sox2 expression was primarily restricted to selective niches of CGRP staining neuroepithelial cells. Allergen-induced goblet cell differentiation and mucus production was absent in the respiratory epithelium lacking Sox2. In vitro, Sox2 activated promoter-luciferase reporter constructs for differentiation markers characteristic of Clara, ciliated, and goblet cells, Scgb1a1, FoxJ1, and Agr2, respectively. Sox2 physically interacted with Smad3 and inhibited TGF-beta1/Smad3-mediated transcriptional activity in vitro, a pathway that negatively regulates proliferation. Sox2 is required for proliferation and differentiation of Clara cells that serve as the progenitor cells from which Clara, ciliated, and goblet cells are derived.
鼠肺的细支气管由单层柱状上皮细胞组成，这些细胞包括纤毛细胞、Clara 细胞和杯状细胞，它们共同介导屏障功能、黏液清除和先天宿主防御，对肺的稳态至关重要。在本工作中，我们证明 Sox2 在 Clara 细胞中的表达对于出生后肺细支气管中纤毛细胞、Clara 细胞和杯状细胞的分化是必需的。利用 Scgb1a1-Cre 选择性地在 Clara 细胞中删除该基因，导致 Sox2 在围产期和出生后发育过程中逐渐丢失。细支气管细胞的增殖率降低，并伴有未分化的立方-鳞状上皮形成，缺乏 Clara 细胞（Scgb1a1）、纤毛细胞（FoxJ1 和α-微管蛋白）和杯状细胞（Spdef 和 Muc5AC）的标志物表达。成年时，细支气管细胞数量减少，Sox2 在细支气管上皮的广泛区域缺失，此时残余的 Sox2 表达主要局限于 CGRP 染色神经上皮细胞的选择性龛位。缺乏 Sox2 的呼吸上皮中，过敏原诱导的杯状细胞分化和粘液产生缺失。在体外，Sox2 激活了分别代表 Clara、纤毛和杯状细胞的分化标志物的启动子-荧光素酶报告基因构建体，即 Scgb1a1、FoxJ1 和 Agr2。Sox2 与 Smad3 相互作用，并抑制 TGF-β1/Smad3 介导的体外转录活性，该途径负调节增殖。Sox2 对于作为 Clara、纤毛和杯状细胞的祖细胞的 Clara 细胞的增殖和分化是必需的。
