MAP kinase-mediated signalling to nucleosomes and immediate-early gene induction

Extracellular signals are transduced into the nucleus through a variety of sig-nailing mechanisms to elicit changes in patterns of gene expression. Th is review is focused on the MAP Kinase cascades and the part they play in t he induction of immediate-early (IE) genes. We discuss the MAP Kinases and their downstream effectors that are known to phosphorylate substrates in th e nucleus. In addition to phosphorylating specific transcription factors, M AP kinases and their downstream kinases are implicated in eliciting rapidly targeted alterations in the chromatin environment of specific genes by mod ulating the phosphorylation and/or acetylation of nucleosomal and chromatin proteins.