NOTCH reprograms mitochondrial metabolism for proinflammatory macrophage activation
Jun Xu, … , Samuel W. French, Hidekazu Tsukamoto
Jun Xu, … , Samuel W. French, Hidekazu Tsukamoto
Published March 23, 2015
Citation Information: J Clin Invest. 2015;125(4):1579-1590. https://doi.org/10.1172/JCI76468.
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Research Article Immunology

NOTCH reprograms mitochondrial metabolism for proinflammatory macrophage activation

Abstract

Metabolic reprogramming is implicated in macrophage activation, but the underlying mechanisms are poorly understood. Here, we demonstrate that the NOTCH1 pathway dictates activation of M1 phenotypes in isolated mouse hepatic macrophages (HMacs) and in a murine macrophage cell line by coupling transcriptional upregulation of M1 genes with metabolic upregulation of mitochondrial oxidative phosphorylation and ROS (mtROS) to augment induction of M1 genes. Enhanced mitochondrial glucose oxidation was achieved by increased recruitment of the NOTCH1 intracellular domain (NICD1) to nuclear and mitochondrial genes that encode respiratory chain components and by NOTCH-dependent induction of pyruvate dehydrogenase phosphatase 1 (Pdp1) expression, pyruvate dehydrogenase activity, and glucose flux to the TCA cycle. As such, inhibition of the NOTCH pathway or Pdp1 knockdown abrogated glucose oxidation, mtROS, and M1 gene expression. Conditional NOTCH1 deficiency in the myeloid lineage attenuated HMac M1 activation and inflammation in a murine model of alcoholic steatohepatitis and markedly reduced lethality following endotoxin-mediated fulminant hepatitis in mice. In vivo monocyte tracking further demonstrated the requirement of NOTCH1 for the migration of blood monocytes into the liver and subsequent M1 differentiation. Together, these results reveal that NOTCH1 promotes reprogramming of mitochondrial metabolism for M1 macrophage activation.

Authors

Jun Xu, Feng Chi, Tongsheng Guo, Vasu Punj, W.N. Paul Lee, Samuel W. French, Hidekazu Tsukamoto

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Figure 1

NOTCH-dependent expression of M1 genes.

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NOTCH-dependent expression of M1 genes. (A) Expression of M1 genes and (...
(A) Expression of M1 genes and (B) NOTCH receptors, Notch1 and Notch2, ligand, Dll4, and target, Hes1, in HMacs from control (Ctrl), high-fat diet–overfed (OF), alcohol (Alc), or combined OF+Alc mice (n = 3–5 per group). *P < 0.01, #P < 0.05, 1-way ANOVA. (C) Immunoblot showing increased NICD1 in HMacs from the OF+Alc mice. Results are representative of 4 different experiments. (D) DAPT suppresses gene expression in HMacs from OF+Alc mice (n = 3–5 per group). The dashed line refers to the mRNA levels of untreated HMacs, which are set at 1 for comparisons with DAPT-treated HMacs, both of which were isolated from the OF+Alc mice. *P < 0.05 vs. DAPT-untreated cells, t test. (E) Gene expression in cultured HMacs from WT and Notch1 KO mice treated with or without LPS (10 ng/ml, 4 hours) (n = 6 per group). *P < 0.05 vs. WT, #P < 0.05 vs. WT+LPS, 1-way ANOVA. (F) Average ChIP enrichment signals are shown over regions spanning ±5 kb around the transcription start sites (TSSs) of all the mouse genes from UCSC RefSeq database. Blue and red lines indicate the input (no immunoprecipitation) level and NICD1 enrichment by ChIP-seq, respectively. (G) Integrative Genomics Viewer genome browser tracks show the level of NICD1 enrichment near the Nos2 transcription start site in ChIP samples (blue) over input (red). Different genomic coordinates and genome window size for Nos2 (chr11:101,691,391-101,717,344; 26 kb) are shown with mm9 reference sequence (RefSeq) data. The transcription start site is shown by the dashed line.