Increased presence of nuclear DNAJA3 and upregulation of cytosolic STAT1 and of nucleic acid sensors trigger innate immunity in the ClpP-null mouse

Neurogenetics. 2021 Oct;22(4):297-312. doi: 10.1007/s10048-021-00657-2. Epub 2021 Aug 3.


Mitochondrial dysfunction may activate innate immunity, e.g. upon abnormal handling of mitochondrial DNA in TFAM mutants or in altered mitophagy. Recent reports showed that also deletion of mitochondrial matrix peptidase ClpP in mice triggers transcriptional upregulation of inflammatory factors. Here, we studied ClpP-null mouse brain at two ages and mouse embryonal fibroblasts, to identify which signaling pathways are responsible, employing mass spectrometry, subcellular fractionation, immunoblots, and reverse transcriptase polymerase chain reaction. Several mitochondrial unfolded protein response factors showed accumulation and altered migration in blue-native gels, prominently the co-chaperone DNAJA3. Its mitochondrial dysregulation increased also its extra-mitochondrial abundance in the nucleus, a relevant observation given that DNAJA3 modulates innate immunity. Similar observations were made for STAT1, a putative DNAJA3 interactor. Elevated expression was observed not only for the transcription factors Stat1/2, but also for two interferon-stimulated genes (Ifi44, Gbp3). Inflammatory responses were strongest for the RLR pattern recognition receptors (Ddx58, Ifih1, Oasl2, Trim25) and several cytosolic nucleic acid sensors (Ifit1, Ifit3, Oas1b, Ifi204, Mnda). The consistent dysregulation of these factors from an early age might influence also human Perrault syndrome, where ClpP loss-of-function leads to early infertility and deafness, with subsequent widespread neurodegeneration.

Keywords: Ataxia; Leukodystrophy; MTRNR1; Mitochondrial amino acid tRNA synthetases; POLG; PRLTS3; Release of mtDNA and mtRNA; TWINKLE; cGAS-STING.

Publication types

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

MeSH terms

  • Animals
  • Cytosol / immunology
  • Cytosol / metabolism
  • DNA, Mitochondrial / genetics
  • DNA, Mitochondrial / immunology
  • HSP40 Heat-Shock Proteins / immunology
  • HSP40 Heat-Shock Proteins / metabolism*
  • Immunity, Innate / immunology*
  • Mice
  • Mitochondria / genetics
  • Mitochondria / immunology
  • Nucleic Acids / immunology
  • Nucleic Acids / metabolism*
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / immunology
  • STAT1 Transcription Factor / immunology
  • STAT1 Transcription Factor / metabolism*
  • Up-Regulation


  • DNA, Mitochondrial
  • Dnaja3 protein, mouse
  • HSP40 Heat-Shock Proteins
  • Nucleic Acids
  • RNA-Binding Proteins
  • STAT1 Transcription Factor
  • Stat1 protein, mouse