Lower Environmental Temperature Reduces Protein Aggregation
Low environmental temperature has been shown to modestly extend life, and there are a number of examples of similar species in which those dwelling in a colder environment exhibit a longer life span. Some thought has gone into identifying mechanisms responsible for this effect, but the effect size really isn't large enough for a great deal of interest to be devoted to the development of therapies based on these mechanisms. Similarly, there is some suggestion that lower body temperature might slow aging in warm blooded species. The work here notes one of the potential mechanisms linking environmental temperature with protein aggregation, a feature of aging. It is again a question as to whether effect sizes are large enough to be in any way interesting as a basis for further investigation.
Extreme low temperatures are detrimental, but a moderate decrease in body temperature can have beneficial effects for the organism. In fact, lowering body temperature extends longevity in both poikilotherms (for example Caenorhabditis elegans, Drosophila melanogaster, and distinct fish species) and homeotherms such as rodents. Aging is a primary risk factor for neurodegenerative disorders that involve protein aggregation. Because lowering body temperature is one of the most effective mechanisms to extend longevity in both poikilotherms and homeotherms, a better understanding of cold-induced changes can lead to converging modifiers of pathological protein aggregation.
Here, we find that cold temperature (15 °C) selectively induces the trypsin-like activity of the proteasome in Caenorhabditis elegans through PSME-3, the worm orthologue of human PA28γ/PSME3. This proteasome activator is required for cold-induced longevity and ameliorates age-related deficits in protein degradation. Moreover, cold-induced PA28γ/PSME-3 diminishes protein aggregation in C. elegans models of age-related diseases such as Huntington's and amyotrophic lateral sclerosis. Notably, exposure of human cells to moderate cold temperature (36 °C) also activates trypsin-like activity through PA28γ/PSME3, reducing disease-related protein aggregation and neurodegeneration. Together, our findings reveal a beneficial role of cold temperature that crosses evolutionary boundaries with potential implications for multi-disease prevention.