Hypertonic stress induces rapid and widespread protein damage in C. elegans

Am J Physiol Cell Physiol. 2011 Sep;301(3):C566-76. doi: 10.1152/ajpcell.00030.2011. Epub 2011 May 25.

Abstract

Proteostasis is defined as the homeostatic mechanisms that maintain the function of all cytoplasmic proteins. We recently demonstrated that the capacity of the proteostasis network is a critical factor that defines the limits of cellular and organismal survival in hypertonic environments. The current studies were performed to determine the extent of protein damage induced by cellular water loss. Using worm strains expressing fluorescently tagged foreign and endogenous proteins and proteins with temperature-sensitive point mutations, we demonstrate that hypertonic stress causes aggregation and misfolding of diverse proteins in multiple cell types. Protein damage is rapid. Aggregation of a polyglutamine yellow fluorescent protein reporter is observable with <1 h of hypertonic stress, and aggregate volume doubles approximately every 10 min. Aggregate formation is irreversible and occurs after as little as 10 min of exposure to hypertonic conditions. To determine whether endogenous proteins are aggregated by hypertonic stress, we quantified the relative amount of total cellular protein present in detergent-insoluble extracts. Exposure for 4 h to 400 mM or 500 mM NaCl induced a 55-120% increase in endogenous protein aggregation. Inhibition of insulin signaling or acclimation to mild hypertonic stress increased survival under extreme hypertonic conditions and prevented aggregation of endogenous proteins. Our results demonstrate that hypertonic stress causes widespread and dramatic protein damage and that cells have a significant capacity to remodel the network of proteins that function to maintain proteostasis. These findings have important implications for understanding how cells cope with hypertonic stress and other protein-damaging stressors.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acclimatization / physiology
  • Animals
  • Animals, Genetically Modified
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Caenorhabditis elegans / drug effects*
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / antagonists & inhibitors
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Cell Nucleus / metabolism
  • Forkhead Transcription Factors
  • Genes, Reporter / genetics
  • Inclusion Bodies / metabolism
  • Insulin / metabolism
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Movement / drug effects
  • Muscle Cells / drug effects
  • Muscle Cells / metabolism
  • Muscle Cells / pathology
  • Myofibrils / metabolism
  • Particle Size
  • Peptides / genetics
  • Peptides / metabolism
  • Pharynx / drug effects
  • Pharynx / metabolism
  • Protein Denaturation / drug effects
  • Protein Folding / drug effects
  • Protein Kinases / genetics
  • Protein Kinases / metabolism
  • Proteoglycans / genetics
  • Proteoglycans / metabolism
  • RNA, Double-Stranded / administration & dosage
  • RNA, Double-Stranded / pharmacology
  • Receptor, Insulin / antagonists & inhibitors
  • Receptor, Insulin / genetics
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Saline Solution, Hypertonic / pharmacology*
  • Signal Transduction / drug effects
  • Stress, Physiological / drug effects*
  • Temperature
  • Transcription Factors / deficiency
  • Transcription Factors / genetics
  • Tropomyosin / metabolism
  • alpha-Synuclein / genetics
  • alpha-Synuclein / metabolism
  • ras Proteins / genetics
  • ras Proteins / metabolism

Substances

  • Bacterial Proteins
  • Caenorhabditis elegans Proteins
  • Forkhead Transcription Factors
  • Insulin
  • Luminescent Proteins
  • Membrane Proteins
  • Peptides
  • Proteoglycans
  • RNA, Double-Stranded
  • Recombinant Fusion Proteins
  • Saline Solution, Hypertonic
  • Transcription Factors
  • Tropomyosin
  • UNC-15 protein, C elegans
  • alpha-Synuclein
  • daf-16 protein, C elegans
  • red fluorescent protein
  • unc-52 protein, C elegans
  • yellow fluorescent protein, Bacteria
  • let-60 protein, C elegans
  • polyglutamine
  • Protein Kinases
  • DAF-2 protein, C elegans
  • Receptor, Insulin
  • KIN-19 protein, C elegans
  • ras Proteins