Stress-activated signalling pathways in yeast

Eukaryotic cells have developed response mechanisms to combat the harmful effects of a variety of stress conditions. In the majority of cases, such responses involve changes in the gene expression pattern of the cell, leading to increased levels and activities of proteins that have stress-protective functions. Over the last few years, considerable progress has been made in understanding how stress-dependent transcriptional changes are brought about, and it transpires that the underlying mechanisms are highly conserved, being similar in organisms ranging from yeast to man. Many of the stress signals derive from the extracellular environment and accordingly these signals require transduction fi om the cell surface to the nucleus. This is accomplished through stress-activated signalling pathways, key amongst which are the highly conserved stress-activated MAP kinase pathways. Stimulation of these pathways leads to the increased activity of specific transcription factors and consequently the increased expression of certain stress-related genes. In this review, we focus on the progress that has been made in understanding these stress responses in yeast.