Distinct Thermosensitive Activation of HSF1 and HSF2 in Immune Cells During Aging

Heat shock factors (HSF1 and HSF2) critically maintain proteostasis under stress, yet their activation across the continuum of rising temperatures is incompletely understood. Furthermore, how age impacts thermally driven rheostatic changes in stress responses is not fully elucidated. Here, we investigate how different temperature levels impact HSF1 and HSF2 in Jurkat T cells and splenocytes from young and aged mice. Using Western blotting, EMSA, RT-qPCR, immunofluorescence, and co-immunoprecipitation, we examined heat shock response changes across a range of thermal conditions. Unlike most cell types that require 42°C for HSF1 activation, Jurkat cells maximally responded at 41°C and splenocytes at 40°C. Optimal HSF1 activation coincided with maximal nuclear translocation, Ser326 phosphorylation, SIRT1 protein levels, and HSP RNA levels. By contrast, HSF2 nuclear translocation required a higher temperature (42°C) than HSF1. Age reduced HSF1 protein levels and nuclear translocation during thermal stress, while HSF2 protein levels were significantly elevated. These findings reveal distinct temperature-sensitive patterns of HSF1 and HSF2 activation of immunocytes during heat stress and identify age-associated alterations in this response.