Characterization of the Proteostasis Roles of Glycerol Accumulation, Protein Degradation and Protein Synthesis during Osmotic Stress in C. elegans
Figure 5
Effect of glycerol accumulation on protein misfolding.
A: Effect of osm-11 RNAi on motility of worms exposed acutely to 500, 600 or 700 mM NaCl. Motility of osm-11(RNAi) worms was not significantly (P>0.1) different from that of osm-11 mutants exposed to the same NaCl levels (Figure 4A) confirming that silencing of the gene by RNAi elevates whole animal glycerol levels. B, C: Expression of mutant phenotypes in let-60 and unc-15 temperature sensitive mutant worms exposed to 300 mM NaCl at 16°C (B) or 51 mM NaCl at 25°C (C). let-60 and unc-15 encode a ras GTPase and paramyosin, respectively. As we have shown previously [6], hypertonic stress induces the mutant phenotype at low or permissive temperatures (i.e., 16°C) suggesting that water loss causes protein misfolding. Therefore, elevated glycerol levels do not suppress hypertonic stress- or temperature-induced expression of the let-60 and unc-15 mutant phenotypes. Control and osm-11(RNAi) worms were fed bacteria expressing a nonspecific dsRNA or osm-11 dsRNA, respectively. (n = 6–9 experiments, each with 20–50 worms/experiments). D: Effect of RNAi knockdown of osm-11 on survival during heat stress. Increased temperature causes protein misfolding and decreased survival [24], [25]. Elevated glycerol levels in osm-11(RNAi) worms do not enhance survival during heat shock. (n = 3–7 experiments with 15–40 worms/experiment).