Abstract
Iron–sulfur (Fe-S) clusters are ancient cofactors in cells and participate in diverse biochemical functions, including electron transfer and enzymatic catalysis. Although cell lines derived from individuals carrying mutations in the Fe-S cluster biogenesis pathway or siRNA-mediated knockdown of the Fe-S assembly components provide excellent models for investigating Fe-S cluster formation in mammalian cells, these experimental strategies focus on the consequences of prolonged impairment of Fe-S assembly. Here, we constructed and expressed dominant–negative variants of the primary Fe-S biogenesis scaffold protein iron–sulfur cluster assembly enzyme 2 (ISCU2) in human HEK293 cells. This approach enabled us to study the early metabolic reprogramming associated with loss of Fe-S– containing proteins in several major cellular compartments. Using multiple metabolomics platforms, we observed a 12-fold increase in intracellular citrate content in Fe-S– deficient cells, a surge that was due to loss of aconitase activity. The excess citrate was generated from glucose-derived acetyl-CoA, and global analysis of cellular lipids revealed that fatty acid biosynthesis increased markedly relative to cellular proliferation rates in Fe-S– deficient cells. We also observed intracellular lipid droplet accumulation in both acutely Fe-S– deficient cells and iron-starved cells. We conclude that deficient Fe-S biogenesis and acute iron deficiency rapidly increase cellular citrate concentrations, leading to fatty acid synthesis and cytosolic lipid droplet formation. Our findings uncover a potential cause of cellular steatosis in nonadipose tissues.
Original language | English (US) |
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Pages (from-to) | 8297-8311 |
Number of pages | 15 |
Journal | Journal of Biological Chemistry |
Volume | 293 |
Issue number | 21 |
DOIs | |
State | Published - May 25 2018 |
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology