Mitochondrial E3 ligase MARCH5 is a safeguard against DNA-PKcs-mediated immune signaling in mitochondria-damaged cells

• Published in: Cell death & disease Vol. 14; no. 12; p. 788
• Main Authors: Heo, June, Park, Yeon-Ji, Kim, Yonghyeon, Lee, Ho-Soo, Kim, Jeongah, Kwon, Soon-Hwan, Kang, Myeong-Gyun, Rhee, Hyun-Woo, Sun, Woong, Lee, Jae-Ho, Cho, Hyeseong
• Format: Journal Article
• Language: English
• Published: England Springer Nature B.V 01.12.2023; Nature Publishing Group UK; Nature Publishing Group
• Subjects: Copy number; DNA damage; DNA, Mitochondrial - genetics; DNA, Mitochondrial - metabolism; DNA-dependent protein kinase; Endonuclease; Humans; Immune response; Immune response (cell-mediated); Inflammation; Interferon; Interferons - metabolism; Lipopolysaccharides; Lipopolysaccharides - metabolism; Macrophages; Membrane Proteins - metabolism; Mitochondria - metabolism; Mitochondrial DNA; mRNA; RNA, Messenger - metabolism; Transcription; Ubiquitin-protein ligase; Ubiquitin-Protein Ligases - metabolism
• ISSN: 2041-4889; 2041-4889
• DOI: 10.1038/s41419-023-06315-9

Mitochondrial dysfunction is important in various chronic degenerative disorders, and aberrant immune responses elicited by cytoplasmic mitochondrial DNA (mtDNA) may be related. Here, we developed mtDNA-targeted MTERF1-FokI and TFAM-FokI endonuclease systems to induce mitochondrial DNA double-strand breaks (mtDSBs). In these cells, the mtDNA copy number was significantly reduced upon mtDSB induction. Interestingly, in cGAS knockout cells, synthesis of interferon β1 and interferon-stimulated gene was increased upon mtDSB induction. We found that mtDSBs activated DNA-PKcs and HSPA8 in a VDAC1-dependent manner. Importantly, the mitochondrial E3 ligase MARCH5 bound active DNA-PKcs in cells with mtDSBs and reduced the type І interferon response through the degradation of DNA-PKcs. Likewise, mitochondrial damage caused by LPS treatment in RAW264.7 macrophage cells increased phospho-HSPA8 levels and the synthesis of mIFNB1 mRNA in a DNA-PKcs-dependent manner. Accordingly, in March5 knockout macrophages, phospho-HSPA8 levels and the synthesis of mIFNB1 mRNA were prolonged after LPS stimulation. Together, cytoplasmic mtDNA elicits a cellular immune response through DNA-PKcs, and mitochondrial MARCH5 may be a safeguard to prevent persistent inflammatory reactions.