Cell population dynamics (apoptosis, mitosis, and cell-cell communication)during disruption of homeostasis

The sequence of events involved in maintenance of homeostasis must encompas s mechanisms within single cells as well as interactions between cells with in a population. To investigate the interaction among these inter- and intr acellular mechanisms, disruption of homeostasis by serum deprivation was pe rformed in WB-F344, a normal diploid epithelial cell line. Changes in cell- cell communication (gap junction function) at the population level and in i ndividual cells were monitored using the scrape load/dye transfer and fluor escence redistribution after photobleaching assays. Apoptosis and mitosis w ere measured using internucleosomal DNA ladder assays and fluorescence-acti vated cell sorting. The results indicate that a common element in early apo ptosis and early mitosis is sustained gap junction function. As cell life ( mitosis) and cell death (apoptosis) progressed, a common process of change in gap junction function occurred. A transient stimulation of mitosis conco mitant with increased apoptosis was also observed during serum deprivation. Gap junctions may play a regulatory role during initiation of these opposi te yet equally important mechanisms of maintaining homeostasis, This model system is useful for further studies on the relationships among inter- and intracellular mechanisms of homeostasis. (C) 2000 Academic Press.