Identification of glucocorticoid-regulated genes that control cell proliferation during murine respiratory development
Identification of glucocorticoid-regulated genes that control cell proliferation during murine respiratory development
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DOI：
10.1113/jphysiol.2007.136796
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发表时间：
2007-11-15
影响因子：
5.5
通讯作者：
Cole, Timothy J.
中科院分区：
文献类型：
--
作者：
Bird, Anthony D.;Tan, Kheng H.;Cole, Timothy J.
糖皮质激素在胎儿呼吸发育中起着至关重要的作用，它通过细胞内糖皮质激素受体（GR）来调节关键靶基因的转录。GR基因缺失的小鼠由于与细胞过多和肺不张相关的呼吸功能障碍在出生时死亡。为了确定与这种肺部表型相关的事件，我们检测了围产期细胞增殖率和凋亡指数。我们证明，与野生型对照组相比，妊娠第18.5天的GR基因缺失小鼠肺细胞增殖率显著增加（1.8倍，P<0.05），而凋亡无变化。为了研究潜在的分子机制，我们在妊娠第18.5天通过微阵列分析比较了全基因组表达谱。与细胞增殖、分裂和细胞周期相关的通路显著下调，而与碳水化合物代谢、激酶活性和免疫反应相关的通路则显著上调。通过定量逆转录聚合酶链反应和/或Northern分析验证了基因表达的差异水平。在妊娠第18.5天GR基因缺失小鼠肺中差异表达的关键增殖调节因子包括p21（CIP1）（降低2.9倍，P<0.05），一种细胞周期的负调节因子，以及Mdk（增加6.0倍，P<0.05），一种肺生长因子。在妊娠第18.5天GR基因缺失小鼠肺中表达更低的基因包括Chi3l3（11倍，P<0.05），一种巨噬细胞炎症反应基因，以及Ela1（9.4倍，P<0.05），一种细胞外基质重塑酶。我们的结果表明，GR在胎儿晚期肺发育过程中影响许多调节过程的转录状态。在这些过程中包括细胞增殖，GR诱导细胞周期抑制因子的表达，同时抑制一种特征明确的细胞周期刺激因子的诱导。
Glucocorticoids play a vital role in fetal respiratory development and act via the intracellular glucocorticoid receptor (GR) to regulate transcription of key target genes. GR-null mice die at birth due to respiratory dysfunction associated with hypercellularity and atelectasis. To identify events associated with this lung phenotype we examined perinatal cellular proliferation rates and apoptotic indices. We demonstrate that compared to wild-type controls, day 18.5 postcoitum ( p. c.) GR-null mouse lungs display significantly increased cell proliferation rates (1.8-fold P < 0.05) and no change in apoptosis. To examine underlying molecular mechanisms, we compared whole genome expression profiles by microarray analysis at 18.5 days p. c. Pathways relating to cell proliferation, division and cell cycle were significantly down-regulated while pathways relating to carbohydrate metabolism, kinase activities and immune responses were significantly up-regulated. Differential levels of gene expression were verified by quantitative-RT-PCR and/or Northern analysis. Key regulators of proliferation differentially expressed in the lung of 18.5 p. c. GR-null lungs included p21(CIP1) ( decreased 2.9-fold, P < 0.05), a negative regulator of the cell cycle, and Mdk (increased 6.0-fold, P < 0.05), a lung growth factor. The more under-expressed genes in 18.5 p. c. GR-null lungs included Chi3l3 (11-fold, P < 0.05), a macrophage inflammatory response gene and Ela1 (9.4-fold, P < 0.05), an extracellular matrix remodeling enzyme. Our results demonstrate that GR affects the transcriptional status of a number of regulatory processes during late fetal lung development. Amongst these processes is cell proliferation whereby GR induces expression of cell cycle repressors while suppressing induction of a well characterized cell cycle stimulator.