Cytosolic DNA inhibits rDNA transcription by retaining the RNA polymerase I transcription machinery.

Cytosolic DNA, derived from cellular damage or microbial infection, functions as a pivotal trigger for the host innate immune responses by activating intracellular DNA-sensing machinery, including the cGAS-STING pathway. However, whether cytosolic DNA is involved in DNA-sensing pathway-independent biological processes remains largely unknown. Here, we show that cytosolic DNA interacts with UBTF and POLR1A, two essential components of the RNA polymerase I transcription machinery, and sequesters these two proteins in the cytoplasm. This retention decreases nuclear UBTF and POLR1A, inhibits rDNA transcription, suppresses protein synthesis, and curtails cell proliferation. Furthermore, we demonstrate that STING-induced autophagy specifically eliminates cytosolic DNA and restores nuclear UBTF and POLR1A, thereby abolishing the inhibitory effects of cytosolic DNA on rDNA transcription, protein synthesis, and cell proliferation. Thus, our findings uncover a novel role of cytosolic DNA in rDNA transcription, suggesting that cytosolic DNA not only activates immune responses but also interferes with cell metabolism.