Redox and mTOR-dependent regulation of plasma lamellar calcium influx controls the senescence-associated secretory phenotype

Abstract

Cellular senescence has evolved as a protective mechanism to arrest growth of cells with oncogenic potential but is accompanied by the often pathologically deleterious senescence-associated secretory phenotype (SASP). Here we demonstrate an H2O2-dependent functional disruption controlling senescence-associated Ca2+ homeostasis and the SASP. Senescent cells fail to respond to H2O2-dependent plasma lamellar Ca2+ entry when compared to pre-senescent cells. Limiting exposure to senescence-associated H2O2 restores H2O2-dependent Ca2+ entry as well as transient receptor potential cation channel subfamily C member 6 (TRPC6) function. SA-TRPC6 and SASP expression is blocked by restoring Ca2+ entry with the TRP channel antagonist SKF-96365 or by the mTOR inhibitors rapamycin and Ku0063794. Together, our findings provide compelling evidence that redox and mTOR-mediated regulation of Ca2+ entry through TRPC6 modulates SASP gene expression and approaches which preserve normal Ca2+ homeostasis may prove useful in disrupting SASP activity. Impact statement Through its ability to evoke responses from cells in a paracrine fashion, the senescence-associated secretory phenotype (SASP) has been linked to numerous age-associated disease pathologies including tumor invasion, cardiovascular dysfunction, neuroinflammation, osteoarthritis, and renal disease. Strategies which limit the amplitude and duration of SASP serve to delay age-related degenerative decline. Here we demonstrate that the SASP regulation is linked to shifts in intracellular Ca2+ homeostasis and strategies which rescue redox-dependent calcium entry including enzymatic H2O2 scavenging, TRP modulation, or mTOR inhibition block SASP and TRPC6 gene expression. As Ca2+ is indispensable for secretion from both secretory and non-secretory cells, it is exciting to speculate that the expression of plasma lamellar TRP channels critical for the maintenance of intracellular Ca2+ homeostasis may be coordinately regulated with the SASP.

Cellular senescence: the good, the bad and the unknown

“… 109 ) and can modulate the SASP by regulating the homeostasis of the SASP initiators, IL-1α and Ca 2+ (refs. 110 , 111 ). In patients with systemic sclerosis, oxidative stress induces fibroblast senescence and contributes to pro-fibrotic and pro-inflammatory phenotypes 112 .…”

Mechanisms of aging, age-associated diseases, and lifespan determination

“…12,13 Chandrasekaran et al. 14 report the novel mechanism controlling SASP of senescent cells. The authors focused on the role of Ca 2+ homeostasis in the cell.…”