Inhibition of mitochondrial genome expression triggers the activation of CHOP-10 by a cell signaling dependent on the integrated stress response but not the mitochondrial unfolded protein response

• Nuclear genes expression is regulated by mitochondria-to-nucleus communications in response to organelle dysfunction.
• The expression of HSPD1 and ClpP is not increased in response to the inhibition of mitochondrial genome expression.
• Inhibition of mtDNA expression induces CHOP-10 expression by the GCN2/eIF2α/ATF4 axis of the integrated stress response.

Mitochondria-to-nucleus communication, known as retrograde signaling, is important to adjust the nuclear gene expression in response to organelle dysfunction. Among the transcription factors described to respond to mitochondrial stress, CHOP-10 is activated by respiratory chain inhibition, mitochondrial accumulation of unfolded proteins and mtDNA mutations. In this study, we show that altered/impaired expression of mtDNA induces CHOP-10 expression in a signaling pathway that depends on the eIF2α/ATF4 axis of the integrated stress response rather than on the mitochondrial unfolded protein response.