Metabolism
Abstract
B-lymphocytes play major adaptive immune roles, producing antibody and driving T-cell responses. However, how immunometabolism networks support B-cell activation and differentiation in response to distinct receptor stimuli remains incompletely understood. To gain insights, we systematically investigated acute primary human B-cell transcriptional, translational and metabolomic responses to B-cell receptor (BCR), Toll-like receptor 9 (TLR9), CD40-ligand (CD40L), interleukin-4 (IL4) or combinations thereof. T-independent BCR/TLR9 co-stimulation, which drives malignant and autoimmune B-cell states highly induced the transaminase branched chain amino acid transaminase 1 (BCAT1), which localized to lysosomal membranes to support branched chain amino acid synthesis and mechanistic target of rapamycin complex 1 (mTORC1) activation. BCAT1 inhibition blunted BCR/TLR9, but not CD40L/IL4-triggered B-cell proliferation, IL10 expression and BCR/TLR pathway-driven lymphoma xenograft outgrowth. These results provide a valuable resource, reveal receptor-mediated immunometabolism remodeling to support key B-cell phenotypes and identify BCAT1 as an activated B-cell therapeutic target.
Authors
Rui Guo, Yizhe Sun, Matthew Y. Lim, Hardik Shah, Joao A. Paulo, Rahaman A. Ahmed, Weixing Li, Yuchen Zhang, Haopeng Yang, Liang Wei Wang, Daniel Strebinger, Nicholas A. Smith, Meng Li, Merrin Man Long Leong, Michael Lutchenkov, Jin-Hua Liang, Zhixuan Li, Yin Wang, Rishi Puri, Ari Melnick, Michael R. Green, John M. Asara, Adonia E. Papathanassiu, Duane R. Wesemann, Steven P. Gygi, Vamsi K. Mootha, Benjamin E. Gewurz
Abstract
Metabolic dysfunction–associated steatohepatitis (MASH) is a globally prevalent but intractable disease lacking effective pharmacotherapies. Here, we performed an integrated multilayered screening for pathogenic genes and druggable targets for MASH. We identified the subclass of metabolite-sensing G protein–coupled receptors, specifically GPR31, a critical contributor to MASH occurrence, which, to our knowledge, was previously uncharacterized. Mechanistically, Gαi3 is the essential downstream effector for the pro-MASH efficiency of GPR31 via glycosylation-dependent interaction with GPR31 and extra activation of PKCδ-MAPK signaling. Hepatocyte-specific GPR31 deficiency robustly blocked hepatic lipotoxicity and fibrosis in a mouse model of diet-induced MASH, whereas expression of the GPR31 transgene aggravated MASH development. Of translational importance, we developed a small-molecule inhibitor, named G4451, that specifically inhibits the GPR31-Gαi3 interaction by targeting the GPR31 conformational transition. Encouragingly, oral administration of G4451 effectively blocked MASH progression in preclinical models in both rodents and nonhuman primates. Collectively, the present study provides proof of concept that interference with GPR31 constitutes an attractive therapeutic strategy for MASH.
Authors
Xiao-Jing Zhang, Jiajun Fu, Xu Cheng, Hong Shen, Hailong Yang, Kun Wang, Wei Li, Han Tian, Tian Tian, Junjie Zhou, Song Tian, Zhouxiang Wang, Juan Wan, Lan Bai, Hongfei Duan, Xin Zhang, Ruifeng Tian, Haibo Xu, Rufang Liao, Toujun Zou, Jing Shi, Weiyi Qu, Liang Fang, Jingjing Cai, Peng Zhang, Zhi-Gang She, Jingwei Jiang, Yufeng Hu, Yibin Wang, Hongliang Li
Abstract
A single bout of exercise improves muscle insulin sensitivity for up to 48 hours via the AMP-activated protein kinase (AMPK). Limb ischemia activates AMPK in muscle, and subsequent reperfusion enhances insulin-stimulated vasodilation, potentially eliciting a more pronounced exercise effect with reduced workload. Here, we investigated the combined effect of upper leg intermittent ischemia-reperfusion (IIR) and continuous knee-extension exercise on muscle insulin sensitivity regulation. We found that IIR-exercise potentiated AMPK activation and muscle insulin sensitivity. The potentiating effect of IIR-exercise on muscle insulin sensitivity was associated with increased insulin-stimulated blood flow in parallel with enhanced phosphorylation of endothelial nitric oxide synthase. Metabolomics analyses demonstrated a suppression of muscle medium-chain acylcarnitines during IIR-exercise, which correlated with insulin sensitivity and was consistent with findings in isolated rat muscle treated with Decanoyl-L-carnitine. Collectively, combining IIR with low-to-moderate intensity exercise may represent a promising intervention to effectively enhance muscle insulin sensitivity. This approach could offer potential for mitigating muscle insulin resistance in clinical settings and among individuals with lower physical activity levels.
Authors
Kohei Kido, Janne R. Hingst, Johan Onslev, Kim A. Sjøberg, Jesper B. Birk, Nicolas O. Eskesen, Tongzhu Zhou, Kentaro Kawanaka, Jesper F. Havelund, Nils J. Færgeman, Ylva Hellsten, Jørgen F.P. Wojtaszewski, Rasmus Kjøbsted
Abstract
Elevated glucocorticoid (GC) levels are common in conditions such as aging, chronic stress, Cushing syndrome, and GC therapy. While GCs suppress inflammation through the glucocorticoid receptor (GR), they also cause metabolic side effects. Investigating alternative pathways beyond GR activation is crucial for reducing these side effects. Our phosphoproteomics analysis revealed that glucocorticoid exposure promotes phosphorylation at the RxxS motifs of multiple proteins in preadipocytes, including those mediated by Serum- and glucocorticoid-induced kinase 3 (SGK3). SGK3 is a key mediator of glucocorticoid-induced adipogenesis, as shown by impaired adipogenesis following SGK3 inhibition or genetic ablation. Sgk3 knockout mice were resistant to glucocorticoid- or high-fat diet-induced obesity, and PROTAC targeting SGK3 reduced adipogenesis in both obese mice and a thyroid eye disease cell line. Mechanistically, SGK3 translocated to the nucleus upon glucocorticoid stimulation, interacted with and phosphorylated the BRG1 subunit of the BAF complex, and prevented BRG1 degradation, promoting chromatin remodeling necessary for adipogenesis. These findings highlight SGK3 as a potential therapeutic target to mitigate metabolic side effects of elevated glucocorticoid levels.
Authors
Qilong Chen, Jialu Guo, Yuyi Liu, Tai Du, Jiapei Liu, Yuyao Zhang, Yuming Dai, Mengdi Zhang, Ziqian Zhou, Qiyang Zhang, Caixia Wei, Qiurong Ding, Jun Qin, Qiwei Zhai, Ju Qiu, Mengle Shao, Fang Zhang, Alexander A. Soukas, Ben Zhou
Abstract
Selective and controlled expansion of endogenous β-cells has been pursued as a potential therapy for diabetes. Ideally, such therapies would preserve feedback control of β-cell proliferation to avoid excessive β-cell expansion. Here, we identified a regulator of β-cell proliferation whose inactivation results in controlled β-cell expansion: the protein deacetylase Sirtuin 2 (SIRT2). Sirt2 deletion in β-cells of mice increased β-cell proliferation during hyperglycemia with little effect in homeostatic conditions, indicating preservation of feedback control of β-cell mass. SIRT2 restrains proliferation of human islet β-cells, demonstrating conserved SIRT2 function. Analysis of acetylated proteins in islets treated with a SIRT2 inhibitor revealed that SIRT2 deacetylates enzymes involved in oxidative phosphorylation, dampening the adaptive increase in oxygen consumption during hyperglycemia. At the transcriptomic level, Sirt2 inactivation has context-dependent effects on β-cells, with Sirt2 controlling how β-cells interpret hyperglycemia as a stress. Finally, we provide proof-of-principle that systemic administration of a GLP1-coupled Sirt2-targeting antisense oligonucleotide achieves β-cell Sirt2 inactivation and stimulates β-cell proliferation during hyperglycemia. Overall, these studies identify a therapeutic strategy for increasing β-cell mass in diabetes without circumventing feedback control of β-cell proliferation. Future work should test the extent that these findings translate to human β-cells from individuals with and without diabetes.
Authors
Matthew Wortham, Bastian Ramms, Chun Zeng, Jacqueline R. Benthuysen, Somesh Sai, Dennis P. Pollow, Fenfen Liu, Michael Schlichting, Austin R. Harrington, Bradley Liu, Thazha P. Prakash, Elaine C. Pirie, Han Zhu, Siyouneh Baghdasarian, Sean T. Lee, Victor A. Ruthig, Kristen L. Wells, Johan Auwerx, Orian S. Shirihai, Maike Sander
Abstract
The cystine-xCT transporter–glutathione (GSH)–GPX4 axis is the canonical pathway protecting cells from ferroptosis. While GPX4-targeting ferroptosis-inducing compounds (FINs) act independently of mitochondria, xCT-targeting FINs require mitochondrial lipid peroxidation, though the mechanism remains unclear. Since cysteine is also a precursor for coenzyme A (CoA) biosynthesis, here, we demonstrated that CoA supplementation selectively prevented ferroptosis triggered by xCT inhibition by regulating the mitochondrial thioredoxin system. Our data showed that CoA regulated the in vitro enzymatic activity of mitochondrial thioredoxin reductase (TXNRD2) by covalently modifying the thiol group of cysteine (CoAlation) on Cys-483. Replacing Cys-483 with alanine on TXNRD2 abolished its enzymatic activity and ability to protect cells against ferroptosis. Targeting xCT to limit cysteine import and, therefore, CoA biosynthesis reduced CoAlation on TXNRD2. Furthermore, the fibroblasts from patients with disrupted CoA metabolism demonstrated increased mitochondrial lipid peroxidation. In organotypic brain slice cultures, inhibition of CoA biosynthesis led to an oxidized thioredoxin system, increased mitochondrial lipid peroxidation, and loss of cell viability, which were all rescued by ferrostatin-1. These findings identified CoA-mediated post-translational modification to regulate the thioredoxin system as an alternative ferroptosis protection pathway with potential clinical relevance for patients with disrupted CoA metabolism.
Authors
Chao-Chieh Lin, Yi-Tzu Lin, Ssu-Yu Chen, Yasaman Setayeshpour, Yubin Chen, Denise E. Dunn, Taylor Nguyen, Alexander A. Mestre, Adrija Banerjee, Lalitha Guruprasad, Erik J. Soderblom, Guo-Fang Zhang, Chen-Yong Lin, Valeriy Filonenko, Suh Young Jeong, Scott R. Floyd, Susan J. Hayflick, Ivan Gout, Jen-Tsan Chi
Abstract
While weight loss is highly recommended for those with obesity, >60% will regain their lost weight. This weight cycling is associated with elevated risk of cardiovascular disease, relative to never having lost weight. How weight loss/regain directly influence atherosclerotic inflammation is unknown. Thus, we studied short-term caloric restriction (stCR) in obese hypercholesterolemic mice, without confounding effects from changes in diet composition. Weight loss was found to promote atherosclerosis resolution independent of plasma cholesterol. From single-cell RNA-sequencing and subsequent mechanistic studies, this can be partly attributed to a unique subset of macrophages accumulating with stCR in epididymal white adipose tissue (eWAT) and atherosclerotic plaques. These macrophages, distinguished by high expression of Fcgr4, help to clear necrotic cores in atherosclerotic plaques. Conversely, weight regain (WR) following stCR accelerated atherosclerosis progression with disappearance of Fcgr4+ macrophages from eWAT and plaques. Furthermore, WR caused reprogramming of immune progenitors, sustaining hyper-inflammatory responsiveness. In summary, we have developed a model to investigate the inflammatory effects of weight cycling on atherosclerosis and the interplay between adipose tissue, bone marrow, and plaques. The findings suggest potential approaches to promote atherosclerosis resolution in obesity and weight cycling through induction of Fcgr4+ macrophages and inhibition of immune progenitor reprogramming.
Authors
Bianca Scolaro, Franziska Krautter, Emily J. Brown, Aleepta Guha Ray, Rotem Kalev-Altman, Marie Petitjean, Sofie Delbare, Casey Donahoe, Stephanie Pena, Michela L. Garabedian, Cyrus A. Nikain, Maria Laskou, Ozlem Tufanli, Carmen Hannemann, Myriam Aouadi, Ada Weinstock, Edward A. Fisher
Abstract
SPNS1 is a lysosomal transporter mediating the salvage of lysoglycerophospholipids, the degradative products of lysosomal phospholipid catabolism. However, a role of lysolipid transport and salvage in regulating cellular lipid homeostasis and in disease is lacking. Here, we identified two families with biallelic SPNS1 loss-of-function variants that presented primarily with progressive liver and striated muscle injury. Patient fibroblasts accumulated lysophospholipids including lysoplasmalogens and cholesterol in lysosomes with reduced cellular plasmalogens. Notably, SPNS1 deficiency resulted in reduced biogenesis of cytosolic lipid droplets containing triglycerides and cholesteryl esters. Mechanistically, we found that lysophospholipids transported by SPNS1 into the cytosol quantitatively contributed to triglyceride synthesis while lysosomal buildup of lyso-ether-phospholipid inhibited lysosomal cholesterol egress, effects that were enhanced with inhibition of mTOR. These findings support a gene-disease association and reveal connectivity between lysosomal transport of lysophospholipids and storage of reserve cellular energy as triglyceride and in the regulation of cholesterol homeostasis, processes that become important under nutrient limitation.
Authors
Menglan He, Mei Ding, Michaela Chocholouskova, Cheen Fei Chin, Martin Engvall, Helena Malmgren, Matias Wagner, Marlen C. Lauffer, Jacob Heisinger, May Christine V. Malicdan, Valérie Allamand, Madeleine Durbeej, Angelica M. Delgado-Vega, Thomas Sejersen, Ann Nordgren, Federico Torta, David L. Silver
Abstract
Sustaining the strong rhythmic interactions between cellular adaptations and environmental cues has been posited as essential for preserving the physiological and behavioral alignment of an organism to the proper phase of the daily light/dark (LD) cycle. Here, we demonstrate that mitochondria and synaptic input organization of suprachiasmatic (SCN) vasoactive intestinal peptide–expressing (VIP-expressing) neurons showed circadian rhythmicity. Perturbed mitochondrial dynamics achieved by conditional ablation of the fusogenic protein mitofusin 2 (Mfn2) in VIP neurons caused disrupted circadian oscillation in mitochondria and synapses in SCN VIP neurons, leading to desynchronization of entrainment to the LD cycle in Mfn2-deficient mice that resulted in an advanced phase angle of their locomotor activity onset, alterations in core body temperature, and sleep-wake amount and architecture. Our data provide direct evidence of circadian SCN clock machinery dependence on high-performance, Mfn2-regulated mitochondrial dynamics in VIP neurons for maintaining the coherence in daily biological rhythms of the mammalian organism.
Authors
Milan Stoiljkovic, Jae Eun Song, Hee-kyung Hong, Heiko Endle, Luis Varela, Jonatas Catarino, Xiao-Bing Gao, Zong-Wu Liu, Peter Sotonyi, Sabrina Diano, Jonathan Cedernaes, Joseph T. Bass, Tamas L. Horvath
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is a genetic muscle disease caused by ectopic expression of the toxic protein DUX4, resulting in muscle weakness. However, the mechanism by which DUX4 exerts its toxicity remains unclear. In this study, we observed abnormal iron accumulation in muscles of patients with FSHD and in muscle-specific DUX4-expressing (DUX4-Tg) mice. Treatment with iron chelators, an iron-deficient diet, and genetic modifications inhibiting intracellular uptake of iron did not improve but rather exacerbated FSHD pathology in DUX4-Tg mice. Unexpectedly, however, iron supplementation, either from a high-iron diet or intravenous iron administration, resulted in remarkable improvement in grip strength and running performance in DUX4-Tg mice. Iron supplementation suppressed abnormal iron accumulation and the ferroptosis-related pathway involving increased lipid peroxidation in DUX4-Tg muscle. Muscle-specific DUX4 expression led to retinal vasculopathy, a part of FSHD pathology, which was prevented by iron administration. Furthermore, high-throughput compound screening of the ferroptosis pathway identified drug candidates including Ferrostatin-1 (Fer-1), a potent inhibitor of lipid peroxidation. Treatment with Fer-1 dramatically improved physical function in DUX4-Tg mice. Our findings demonstrate that DUX4-provoked toxicity is involved in the activation of the ferroptosis-related pathway and that supplementary iron could be a promising and readily available therapeutic option for FSHD.
Authors
Kodai Nakamura, Huascar-Pedro Ortuste-Quiroga, Naoki Horii, Shin Fujimaki, Toshiro Moroishi, Keiichi I. Nakayama, Shinjiro Hino, Yoshihiko Saito, Ichizo Nishino, Yusuke Ono
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)