Iron drives anabolic metabolism through active histone demethylation and mTORC1

Abstract All eukaryotic cells require a minimal iron threshold to sustain anabolic metabolism. However, the mechanisms by which cells sense iron to regulate anabolic processes are unclear. Here we report a previously undescribed eukaryotic pathway for iron sensing in which molecular iron is required to sustain active histone demethylation and maintain the expression of critical components of the pro-anabolic mTORC1 pathway. Specifically, we identify the iron-binding histone-demethylase KDM3B as an intrinsic iron sensor that regulates mTORC1 activity by demethylating H3K9me2 at enhancers of a high-affinity leucine transporter, LAT3, and RPTOR. By directly suppressing leucine availability and RAPTOR levels, iron deficiency supersedes other nutrient inputs into mTORC1. This process occurs in vivo and is not an indirect effect by canonical iron-utilizing pathways. Because ancestral eukaryotes share homologues of KDMs and mTORC1 core components, this pathway probably pre-dated the emergence of the other kingdom-specific nutrient sensors for mTORC1.Abstract All eukaryotic cells require a minimal iron threshold to sustain anabolic metabolism. However, the mechanisms by which cells sense iron to regulate anabolic processes are unclear. Here we report a previously undescribed eukaryotic pathway for iron sensing in which molecular iron is required to sustain active histone demethylation and maintain the expression of critical components of the pro-anabolic mTORC1 pathway. Specifically, we identify the iron-binding histone-demethylase KDM3B as an intrinsic iron sensor that regulates mTORC1 activity by demethylating H3K9me2 at enhancers of a high-affinity leucine transporter, LAT3, and RPTOR. By directly suppressing leucine availability and RAPTOR levels, iron deficiency supersedes other nutrient inputs into mTORC1. This process occurs in vivo and is not an indirect effect by canonical iron-utilizing pathways. Because ancestral eukaryotes share homologues of KDMs and mTORC1 core components, this pathway probably pre-dated the emergence of the other kingdom-specific nutrient sensors for mTORC1

mRNA-binding protein tristetraprolin is essential for cardiac response to iron deficiency by regulating mitochondrial function.

細胞質における鉄の出納はiron regulatory protein 1および2（IRP1/2）を介する鉄輸送の制御によって維持されるが，鉄が重要な役割を果たすミトコンドリアにおける鉄欠乏への適応機構は不明であった．本研究では，mRNA結合蛋白tristetraprolin（TTP）が鉄欠乏により発現誘導され，ミトコンドリア電子伝達系における鉄含有蛋白の発現量を鉄利用に合わせて適切に制御することによりミトコンドリア機能を維持することを明らかにした