Studies of cultured pituitary cells have demonstrated dynamic, large-scale fluctuations in the expression of hormones by the many endocrine cell types that make up this tissue. However, whether such fluctuations occur in intact pituitary tissue, and how tissue architecture influences the function of individual cells, was previously unknown. On page , Claire Harper, Julian Davis, Michael White and colleagues make use of recently developed live-imaging techniques to quantify the spatiotemporal organisation of prolactin expression in intact pituitary tissue from transgenic rats. By quantifying activity of the prolactin gene promoter for up to 72 hours, the authors find that the absolute signal intensity and amplitude of the change varies in different regions of the tissue; however, the overall temporal pattern of expression is similar in each region, suggesting long-range synchronised regulation of cellular behaviour. By contrast, such synchronisation is lost when tissue cells are dispersed in culture. Furthermore, several distinct short-range patterns can be detected among neighbouring cells in intact tissues over shorter time periods (15 hours). Therefore, the authors conclude, pituitary tissue exhibits short-term stochastic gene expression by discrete cell ‘ensembles’ that are synchronised by region-specific signals to achieve long-range and long-term coordinated cellular behaviour.
