Chapter 7

Response of Eukaryotes to Stress

Nadia Danilova

Abstract

Eukaryotic stress response involves changes in transcription, translation, and proteostasis. Some changes are similar across many stress responses. Stressors such as misfolded proteins, oxidative stress, viral RNAs, heme deficiency, heat shock, amino acid shortage, and others activate the integrated stress response (ISR) kinases PERK, PKR, HRI, and GCN2; they phosphorylate eIF2α inducing global inhibition of translation. Some stresses, e.g. oxidative and osmotic can activate several kinases. Transcriptional response to stress involves the suppression of genes functioning in energy-consuming processes such as protein biosynthesis and activation of genes that mitigate damage caused by stress. Many stresses interfere with the synthesis and folding of proteins. When unfolded protein level exceeds folding and clearance capacity of the cell, the unfolded protein response is triggered, which increases that capacity by producing more chaperones and proteases. Autophagy is another common response to stress that helps to cleanse the cell of aggregated proteins and dysfunctional organelles and replenish the supply of biosynthetic precursors and energy. There are also responses specific to heat, cold, osmotic, pH, oxidative, and mitochondrial stress. They involve activation of programs that mediate adjustment to specific stress.

Total Pages: 182-223 (42)

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