Hsf1 activation by proteotoxic stress requires concurrent protein synthesis

Area of Science:

• Cellular Biology
• Molecular Biology
• Stress Response

Background:

• Heat shock factor 1 (Hsf1) regulates cellular defense against proteotoxic stress.
• Hsf1 activation increases protein-folding chaperones and degradation machinery.
• The interplay between protein synthesis and proteotoxic stress requires further investigation.

Purpose of the Study:

• To explore the relationship between concurrent protein synthesis and proteotoxic stress.
• To determine if protein synthesis inhibition affects Hsf1 activation.
• To investigate the role of newly synthesized proteins in Hsf1 activation.

Main Methods:

• Utilized the budding yeast, *Saccharomyces cerevisiae*.
• Inhibited protein synthesis using various methods before inducing proteotoxic stress.
• Applied different proteotoxic stresses, including ethanol treatment.
• Examined Hsf1 activation under conditions of translation inhibition and reduced protein synthesis rates.

Main Results:

• Inhibiting protein synthesis prior to proteotoxic stress prevented Hsf1 activation, confirming prior work.
• Other stress-dependent transcription pathways remained activatable despite translation inhibition.
• High concentrations of ethanol induced Hsf1 activation even without protein synthesis.
• Disrupting the assembly or localization of newly synthesized proteins activated Hsf1.

Conclusions:

• Extreme protein-folding stress can induce proteotoxicity independently of ongoing protein synthesis.
• Newly synthesized proteins are particularly vulnerable to proteotoxic conditions.
• Protein aggregation of newly synthesized proteins likely serves as a primary signal for Hsf1 activation during proteotoxic insults.