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. This review is focused on the MAP Kinase cascades and the part they play in the induction of immediate-early (IE) genes. We discuss the MAP Kinases and their downstream effectors that are known to phosphorylate substrates in the nucleus. In addition to phosphorylating specific transcription factors, MAP kinases and their downstream kinases are implicated in eliciting rapidly targeted alterations in the chromatin environment of specific genes by modulating the phosphorylation and/or acetylation of nucleosomal and chromatin proteins.