CELL SIGNALING AND THE CONTROL OF GENE-TRANSCRIPTION

Recent discoveries have led to a better understanding of how signals generated by growth factors, cytokines and hormones elicit changes in gene expression in mammalian cells. Three general strategies of information pathways from the cell surface to the nucleus can be defined, all of which involve protein phosphorylation: (1) activation and translocation of cytoplasmic kinases to the nucleus, leading to changes in transcription-factor functions; (2) direct activation of latent cytoplasmic transcription factors by phosphorylation; and (3) release of transcription factors from cytoplasmic anchor proteins. These information conduits are illustrated by the mitogen-activated protein (MAP) kinase pathway, signal transducer and activator of transcription (Stat) proteins and nuclear factor-kappa B (NF-kappa B), respectively, and are discussed in this article by Dylan Edwards. Regulation of nucleo-cytoplasmic compartmentation emerges as a key aspect of signal transfer.