Centre for Cell Imaging, School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, UK.
J Cell Sci. 2010 Feb 1;123(Pt 3):424-30. doi: 10.1242/jcs.060434.
Gene expression in living cells is highly dynamic, but temporal patterns of gene expression in intact tissues are largely unknown. The mammalian pituitary gland comprises several intermingled cell types, organised as interdigitated networks that interact functionally to generate co-ordinated hormone secretion. Live-cell imaging was used to quantify patterns of reporter gene expression in dispersed lactotrophic cells or intact pituitary tissue from bacterial artificial chromosome (BAC) transgenic rats in which a large prolactin genomic fragment directed expression of luciferase or destabilised enhanced green fluorescent protein (d2EGFP). Prolactin promoter activity in transgenic pituitaries varied with time across different regions of the gland. Although amplitude of transcriptional responses differed, all regions of the gland displayed similar overall patterns of reporter gene expression over a 50-hour period, implying overall co-ordination of cellular behaviour. By contrast, enzymatically dispersed pituitary cell cultures showed unsynchronised fluctuations of promoter activity amongst different cells, suggesting that transcriptional patterns were constrained by tissue architecture. Short-term, high resolution, single cell analyses in prolactin-d2EGFP transgenic pituitary slice preparations showed varying transcriptional patterns with little correlation between adjacent cells. Together, these data suggest that pituitary tissue comprises a series of cell ensembles, which individually display a variety of patterns of short-term stochastic behaviour, but together yield long-range and long-term coordinated behaviour.
活细胞中的基因表达具有高度动态性,但完整组织中基因表达的时间模式在很大程度上是未知的。哺乳动物垂体由几种相互交织的细胞类型组成,这些细胞类型组织成相互交织的网络,这些网络以协调的方式相互作用以产生激素分泌。使用活细胞成像技术来量化分散的催乳素细胞或来自细菌人工染色体 (BAC) 转基因大鼠的完整垂体组织中报告基因表达的模式,其中大的催乳素基因组片段指导荧光素酶或不稳定增强型绿色荧光蛋白 (d2EGFP) 的表达。转基因垂体中催乳素启动子活性随时间在腺体的不同区域而变化。尽管转录反应的幅度不同,但在 50 小时的时间内,腺体的所有区域都显示出相似的报告基因表达总体模式,这意味着细胞行为的总体协调。相比之下,通过酶促分散的垂体细胞培养物显示出不同细胞之间启动子活性的不同步波动,这表明转录模式受到组织结构的限制。在催乳素-d2EGFP 转基因垂体切片制剂的短期、高分辨率、单细胞分析中,显示出不同的转录模式,相邻细胞之间相关性很小。这些数据表明,垂体组织由一系列细胞集合组成,这些细胞集合各自显示出多种短期随机行为的模式,但共同产生远程和长期协调的行为。