Oxidative and nitrative stress and NF-κB signaling contribute to repression of Fe-S cluster biogenesis, whereas inhibition of TLR-driven glycolysis reduces the repression of NFS1 and ISCU. (A-B) ISCU levels decreased when RAW264.7 cells were exposed to 95% oxygen (A) or menadione (B). (C) ISCU levels decreased when RAW264.7 cells were exposed to the NO donor (NOC-18). (D) Low glucose concentrations in the media mitigated the LPS/IFN-γ– or poly(I:C)/IFN-γ–induced suppression of NFS1 and ISCU and partially rescued lipoyl-PDH E2 and FECH levels and aconitase activity. (E) Repression of NFS1 was mitigated by pretreating RAW264.7 cells with MLN120B, an inhibitor of NF-κB signaling, for 1 hour before the addition of LPS/IFN-γ. (F) Levels of NFS1, SDHB, and NDUFS1 decreased in HeLa cells in response to TNF and IFN-γ.