Pharmacologic activation of delta133p53α reduces cellular senescence in progeria patients-derived cells

Abstract

Background: Patients with Hutchinson-Gilford progeria syndrome (HGPS) show accelerated aging phenotypes and have shortened lifespan, with implications in physiological aging processes as well. While therapeutic approaches targeting the disease-causing abnormal protein, progerin, have been developed, further efforts to explore mechanistically distinct and complementary strategies are still critical to better treatment regimens. We previously showed that lentiviral vector-driven expression of delta133p53α, a natural inhibitory isoform of p53, rescued HGPS patients-derived fibroblasts from early entry into cellular senescence, which is a downstream event of progerin-induced DNA damage. We also performed a quantitative high-throughput screen (qHTS) of approved drug and investigational agent libraries, leading to the identification of celastrol and AZD1981 as compounds that upregulate delta133p53a protein levels.

Materials and Methods: To investigate whether celastrol and ADZ1981 upregulate endogenous delta133p53α in HGPS-derived fibroblasts and reduce their senescence-associated phenotypes, we performed western blot assays (delta133p53α, progerin, and p21^WAF1, which mediates p53-induced senescence and is inhibited by delta133p53α), senescence-associated β-galactosidase (SA-β-gal) staining, enzyme-linked immunosorbent assay (IL-6, which is a proinflammatory cytokine secreted from senescent cells), and qRT-PCR assays (p21^WAF1 and IL-6).

Results: Treatment with celastrol (0.1 µM for 24 h) or AZD1981 (10 µM for 24 h) reproducibly increased delta133p53α expression and decreased p21^WAF1 expression in two strains of fibroblasts derived from HGPS patients. These compounds reduced the percentage of SA-β-gal-positive senescent cells and the secretion of IL-6 into culture medium in both of these fibroblast strains, irrespective of their different basal levels of senescence and IL-6 secretion. These compounds had no effect on the level of progerin.

Conclusion: Celastrol and ADZ1981 upregulate endogenous delta133p53α and, reproducing the effects of its vector-driven expression, inhibit cellular senescence and IL-6 secretion in HGPS-derived fibroblasts. Their progerin-independent action suggests that they may synergize with currently available progerin-targeting therapies. This study also warrants further investigation of these compounds for potential applications in other diseases and conditions in which delta133p53a-regulated senescence plays a role.

Keywords: p53 isoform, cellular senescence, IL-6, fibroblasts, aging, Hutchinson-Gilford progeria syndrome, progerin, pharmacologic activation