Skip to main content

Research Repository

Advanced Search

Loss of regulation of protein synthesis and turnover underpins an attenuated stress response in senescent human mesenchymal stem cells

Llewellyn, J; Mallikarjun, V; Gilbert, HTJ; Richardson, SM; Hubbard, SJ; Swift, J; Appleton, E; Osipova, M

Loss of regulation of protein synthesis and turnover underpins an attenuated stress response in senescent human mesenchymal stem cells Thumbnail


Authors

J Llewellyn

V Mallikarjun

SM Richardson

SJ Hubbard

J Swift

E Appleton

M Osipova



Abstract

<jats:p>Cells respond to stress by synthesizing chaperone proteins that seek to correct protein misfolding and maintain function. However, abrogation of protein homeostasis is a hallmark of aging, leading to loss of function and the formation of proteotoxic aggregates characteristic of pathology. Consequently, discovering the underlying molecular causes of this deterioration in proteostasis is key to designing effective interventions to disease or to maintaining cell health in regenerative medicine strategies. Here, we examined primary human mesenchymal stem cells, cultured to a point of replicative senescence and subjected to heat shock, as an in vitro model of the aging stress response. Multi -omics analysis showed how homeostasis components were reduced in senescent cells, caused by dysregulation of a functional network of chaperones, thereby limiting proteostatic competence. Time-resolved analysis of the primary response factors, including those regulating heat shock protein 70 kDa (HSPA1A), revealed that regulatory control is essentially translational. Senescent cells have a reduced capacity for chaperone protein translation and misfolded protein (MFP) turnover, driven by downregulation of ribosomal proteins and loss of the E3 ubiquitin ligase CHIP (C-terminus of HSP70 interacting protein) which marks MFPs for degradation. This limits the cell’s stress response and subsequent recovery. A kinetic model recapitulated these reduced capacities and predicted an accumulation of MFP, a hypothesis supported by evidence of systematic changes to the proteomic fold state. These results thus establish a specific loss of regulatory capacity at the protein, rather than transcript, level and uncover underlying systematic links between aging and loss of protein homeostasis.</jats:p>

Acceptance Date Feb 24, 2023
Publication Date Apr 4, 2023
Journal Proceedings of the National Academy of Sciences
Print ISSN 0027-8424
Publisher National Academy of Sciences
DOI https://doi.org/10.1073/pnas.2210745120
Publisher URL https://www.pnas.org/doi/10.1073/pnas.2210745120

Files







You might also like



Downloadable Citations