HSP90 inhibition in early-passage primary human mesenchymal stem cells subjected to 2 hour heat shock (4 donors)

Cells respond to stress by synthesising chaperone proteins that correct protein misfolding to maintain function. However, protein homeostasis is lost in ageing, leading to aggregates characteristic of protein-folding diseases. Whilst much is known about how these diseases progress, discovering what causes protein-folding to deteriorate could be key to their prevention. Here, we examined primary human mesenchymal stem cells (hMSCs), cultured to a point of replicative senescence and subjected to heat shock, as an in vitro model of the ageing stress response. We found through proteomic analysis that the maintenance of homeostasis deteriorated in senescent cells, coincident with lowered levels of a functional module of chaperone proteins associated with heat shock protein 70 kDa (HSPA1A). Further analysis of the temporal dynamics of the proteomic and transcriptomic stress response revealed a lack of translational capacity to be a limiting factor in the capacity of senescent cells to mitigate proteotoxic stress.