MAPK Signaling

Hogging a Deacetylase to Promote Transcription

Science's STKE  27 Jan 2004:
Vol. 2004, Issue 217, pp. tw33-TW33
DOI: 10.1126/stke.2172004TW33

Exposing yeast to high osmolarity triggers activation of a mitogen-activated protein kinase (MAPK) signaling pathway, enabling their survival by means of the transcriptional activation of osmoresponsive genes--a response coordinated by the MAPK Hog1. The mechanisms whereby Hog1 regulates gene expression, however, have not been fully elucidated. De Nadal et al. screened yeast for osmosensitive mutants and found that, like yeast lacking Hog1, yeast lacking Rpd3 (a histone deacetylase) or Sin3 (a protein that interacts with Rpd3) were sensitive to high osmolarity and showed impaired expression of Hog1-regulated genes in response to osmotic stress. Mutational analysis indicated that the ability of Rpd3 to mediate Hog1-induced transcriptional activation in a LexA-lacZ reporter system depended on its catalytic activity as a deacetylase. Hog1 coprecipitated with Rpd3 and Sin3 in vivo and bound to a Rpd3 fusion protein in vitro. The authors used chromatin immunoprecipitation analysis to show that osmotic stress led to Hog1- dependent association of Rpd3 and Sin3 with the promoter region of an osmoresponsive gene (HSP12), localized histone deacetylation, and Hog1- and Rpd3-dependent recruitment of RNA polymerase II. Thus, transcriptional activation mediated by Hog1 in response to osmotic stress appears to depend on Rpd3 recruitment and histone deacetylation.

E. de Nadal, M. Zapater, P. M. Alepuz, L. Sumoy, G. Mas, F. Posas, The MAPK Hog1 recruits Rpd3 histone deacetylase to activate osmoresponsive genes. Nature 427, 370-374 (2004). [Online Journal]