Impact of Ndufs1 inactivation on the transcriptome of naïve-type mouse embryonic stem cells.

Mitochondrial metabolism is critically involved in the regulation of ESC self-renewal and differentiation, yet the specific role of the respiratory complex components in these processes remains largely unknown. Here, we demonstrate that while respiratory complex I (CI) function is dispensable for the ESC differentiation potential, its loss leads to a profound reduction in proliferation rates.

Deficiency of the core CI subunit Ndufs1 induces mitochondrial reductive stress, characterized by a reduced mitochondrial NAD⁺/NADH ratio and elevated reactive oxygen species levels. The accumulation of mitochondrial NADH acts as a primary signal that negatively regulates ESC proliferation, associated with the activation of the integrated stress response and suppression of the NRF2/PGC-1α/SOD2 antioxidant axis. Our findings identify NADH-induced reductive stress as a critical checkpoint for ESC proliferation and propose that CI acts as a metabolic rheostat, calibrating ESC mitotic activity through mitochondrial-to-nuclear redox signaling.