Pharmacologic activation of Δ133p53α reduces cellular senescence in progeria patients-derived cells

BackgroundPatients 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 {Delta}133p53, 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 {Delta}133p53 protein levels. MethodsTo investigate whether celastrol and ADZ1981 upregulate endogenous {Delta}133p53 in HGPS-derived fibroblasts and reduce their senescence-associated phenotypes, we performed western blot assays ({Delta}133p53, progerin, and p21WAF1, which mediates p53-induced senescence and is inhibited by {Delta}133p53), senescence-associated {beta}-galactosidase (SA-{beta}-gal) staining, enzyme-linked immunosorbent assay (IL-6, which is a proinflammatory cytokine secreted from senescent cells), and qRT-PCR assays (p21WAF1 and IL-6). ResultsTreatment with celastrol (0.1 {micro}M for 24 h) or AZD1981 (10 {micro}M for 24 h) reproducibly increased {Delta}133p53 expression and decreased p21WAF1 expression in two strains of fibroblasts derived from HGPS patients. These compounds reduced the percentage of SA-{beta}-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. ConclusionCelastrol and ADZ1981 upregulate endogenous {Delta}133p53 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 {Delta}133p53-regulated senescence plays a role.