Lactate supports Treg function and immune balance via MGAT1 effects on N-glycosylation in the mitochondria
Jinren Zhou, … , Ling Lu, Bruce R. Blazar
Jinren Zhou, … , Ling Lu, Bruce R. Blazar
Published September 12, 2024
Citation Information: J Clin Invest. 2024;134(20):e175897. https://doi.org/10.1172/JCI175897.
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Research Article Immunology Metabolism

Lactate supports Treg function and immune balance via MGAT1 effects on N-glycosylation in the mitochondria

Abstract

Current research reports that lactate affects Treg metabolism, although the precise mechanism has only been partially elucidated. In this study, we presented evidence demonstrating that elevated lactate levels enhanced cell proliferation, suppressive capabilities, and oxidative phosphorylation (OXPHOS) in human Tregs. The expression levels of Monocarboxylate Transporters 1/2/4 (MCT1/2/4) regulate intracellular lactate concentration, thereby influencing the varying responses observed in naive Tregs and memory Tregs. Through mitochondrial isolation, sequencing, and analysis of human Tregs, we determined that α-1,3-Mannosyl-Glycoprotein 2-β-N-Acetylglucosaminyltransferase (MGAT1) served as the pivotal driver initiating downstream N-glycosylation events involving progranulin (GRN) and hypoxia-upregulated 1 (HYOU1), consequently enhancing Treg OXPHOS. The mechanism by which MGAT1 was upregulated in mitochondria depended on elevated intracellular lactate that promoted the activation of XBP1s. This, in turn, supported MGAT1 transcription as well as the interaction of lactate with the translocase of the mitochondrial outer membrane 70 (TOM70) import receptor, facilitating MGAT1 translocation into mitochondria. Pretreatment of Tregs with lactate reduced mortality in a xenogeneic graft-versus-host disease (GvHD) model. Together, these findings underscored the active regulatory role of lactate in human Treg metabolism through the upregulation of MGAT1 transcription and its facilitated translocation into the mitochondria.

Authors

Jinren Zhou, Jian Gu, Qufei Qian, Yigang Zhang, Tianning Huang, Xiangyu Li, Zhuoqun Liu, Qing Shao, Yuan Liang, Lei Qiao, Xiaozhang Xu, Qiuyang Chen, Zibo Xu, Yu Li, Ji Gao, Yufeng Pan, Yiming Wang, Roderick O’Connor, Keli L. Hippen, Ling Lu, Bruce R. Blazar

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Figure 2

Mitochondrial proteomics show increased MGAT1 expression in TregN in the high lactate environment.

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Mitochondrial proteomics show increased MGAT1 expression in TregN in the...
(A) Isotope concentration peaked 48 hours after adding 14C-sodium lactate into the culture. n = 3. (B) Isotope concentration of 14C-sodium in each organelle increased significantly at 48 hours in TregN and was the highest in mitochondria. n = 6. (C) Differentially expressed proteins of TregN and TregM with 20 mM lactate treatment for 48 hours were performed by limma. (D) Strong TregN and TregM metabolic activation after lactate treatment through a heat map. n = 3. (E) Metabolic pathway scores were analyzed using limma to show the top 5 upregulated metabolic pathways after lactate treatment in TregN and TregM. (F) MGAT1 in TregN and TregM was upregulated after 20 mM lactate treatment for 48 hours from the intersection. (G) Expression of MGAT1 mRNA was elevated in TregN after 20 mM lactate treatment for 48 hours. n = 3. (H) MGAT1 was elevated in TregN after 20 mM lactate treatment for 48 hours. n = 3. (I) Representative images of colocalization of MGAT1 and mitochondria were observed under laser scanning confocal microscopy in TregN (green and magenta merged white at the arrow). Scale bars: 20 μm.(J) The corrected cumulative optical density of colocalization in 2 groups. n = 6. The fluorescence intensity of each group was quantitatively analyzed for the brightest field of 3D video, and 6 copositioned fields were selected and additional blank areas were selected for background elimination. Then, the accumulated light intensity of the fluorescence images was analyzed using ImageJ (accumulated light density after correction is equal to the accumulated light density minus the area of cells to be measured multiplied by the average background light density). Data are represented as mean ± SEM. 2-tailed Student’s t test. *P < 0.05, **P < 0.01, ****P < 0.0001.