Mitochondria-to-nucleus Retrograde Signaling Drives Formation of Cytoplasmic Chromatin and Inflammation in Senescence

Genes Dev. 2020 Mar 1;34(5-6):428-445. doi: 10.1101/gad.331272.119. Epub 2020 Jan 30.

Abstract

Cellular senescence is a potent tumor suppressor mechanism but also contributes to aging and aging-related diseases. Senescence is characterized by a stable cell cycle arrest and a complex proinflammatory secretome, termed the senescence-associated secretory phenotype (SASP). We recently discovered that cytoplasmic chromatin fragments (CCFs), extruded from the nucleus of senescent cells, trigger the SASP through activation of the innate immunity cytosolic DNA sensing cGAS-STING pathway. However, the upstream signaling events that instigate CCF formation remain unknown. Here, we show that dysfunctional mitochondria, linked to down-regulation of nuclear-encoded mitochondrial oxidative phosphorylation genes, trigger a ROS-JNK retrograde signaling pathway that drives CCF formation and hence the SASP. JNK links to 53BP1, a nuclear protein that negatively regulates DNA double-strand break (DSB) end resection and CCF formation. Importantly, we show that low-dose HDAC inhibitors restore expression of most nuclear-encoded mitochondrial oxidative phosphorylation genes, improve mitochondrial function, and suppress CCFs and the SASP in senescent cells. In mouse models, HDAC inhibitors also suppress oxidative stress, CCF, inflammation, and tissue damage caused by senescence-inducing irradiation and/or acetaminophen-induced mitochondria dysfunction. Overall, our findings outline an extended mitochondria-to-nucleus retrograde signaling pathway that initiates formation of CCF during senescence and is a potential target for drug-based interventions to inhibit the proaging SASP.

Keywords: cytoplasmic chromatin; inflammation; mitochondria; senescence.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Nucleus / pathology*
  • Cell Nucleus / physiology
  • Cellular Senescence / physiology*
  • Chromatin / pathology*
  • Cytoplasm / pathology*
  • Gene Expression Regulation, Developmental / drug effects
  • Histone Deacetylase Inhibitors / pharmacology
  • Humans
  • Inflammation / physiopathology
  • MAP Kinase Signaling System / physiology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mitochondria / drug effects
  • Mitochondria / pathology*
  • Mitochondria / physiology
  • Reactive Oxygen Species / metabolism
  • Signal Transduction*
  • Tumor Suppressor p53-Binding Protein 1 / metabolism

Substances

  • Chromatin
  • Histone Deacetylase Inhibitors
  • Reactive Oxygen Species
  • Tumor Suppressor p53-Binding Protein 1