Metabolism
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
Abstract
Elevated cholesterol poses cardiovascular risks. The glucocorticoid receptor (GR) harbors a still undefined role in cholesterol regulation. Here, we report that a coding single nucleotide polymorphism (SNP) in the gene en-coding the GR, rs6190, associated with increased cholesterol in women according to UK Biobank and All Of Us datasets. In SNP-genocopying mice, we found that the SNP enhanced hepatic GR activity to transactivate Pcsk9 and Bhlhe40, negative regulators of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) re-ceptors respectively. In mice, the SNP was sufficient to elevate circulating cholesterol across all lipoprotein frac-tions and the risk and severity of atherosclerotic lesions on the pro-atherogenic hAPOE*2/*2 background. The SNP effect on atherosclerosis was blocked by in vivo liver knockdown of Pcsk9 and Bhlhe40. Also, corti-costerone and testosterone were protective against the mutant GR program in cholesterol and atherosclerosis in male mice, while the SNP effect was additive to estrogen loss in females. Remarkably, we found that the mu-tant GR program was conserved in human hepatocyte-like cells using CRISPR-engineered, SNP-genocopying human induced pluripotent stem cells (hiPSCs). Taken together, our study leverages a non-rare human variant to uncover a novel GR-dependent mechanism contributing to atherogenic risk, particularly in women.
Authors
Hima Bindu Durumutla, April Haller, Greta Noble, Ashok Daniel Prabakaran, Kevin McFarland, Hannah Latimer, Akanksha Rajput, Olukunle Akinborewa, Bahram Namjou-Khales, David Y. Hui, Mattia Quattrocelli
Abstract
Pro-inflammatory signaling in adipocytes is essential for healthy adipose expansion, remodeling, and tissue integrity. We investigated the effects of targeting inflammation in either adipocytes or mammary gland epithelial cells, in the context of mammary tumor development, by locally expressing the anti-inflammatory adenoviral RIDα/β protein complex in a cell type-specific manner. Suppression of adipocyte inflammation (“RIDad mice”) in a mammary tumor model driven by MMTV-PyMT (“PyMT-RIDad mice”) led to an elevated number of tumor-associated macrophages (TAMs) and upregulation of immunoregulatory molecules in the mammary fat pad (MFP). This was accompanied by metabolic dysfunction and abnormal mammary gland development. Importantly, this phenotype correlated with accelerated mammary tumor onset, enhanced growth, and lung metastasis. Tumors in PyMT-RIDad mice exhibited upregulated CD36 expression, suggesting enhanced fatty acid uptake. Conversely, suppression of inflammation in mammary gland epithelial cells by RIDα/β expression (“RIDMMTV mice”) decelerated mammary tumor growth without affecting tumor onset or macrophage accumulation. These findings highlight the differential impact on tumor development exerted through the suppression of inflammatory signals in different cell types in the microenvironment. Our results underscore the role of the suppression of adipocyte inflammation leading to a tumor-friendly microenvironment, promoting mammary cancer progression. This study sheds light on the complex interplay between inflammation, specifically driven by the adipocyte, in breast cancer pathogenesis.
Authors
Dae-Seok Kim, Toshiharu Onodera, Jan-Bernd Funcke, Kyounghee Min, Qingzhang Zhu, Qian Lin, Shiuhwei Chen, Chanmin Joung, Min Kim, R. Max Wynn, Joselin Velasco, Charlotte Lee, Megan Virostek, Chao Li, Philipp E. Scherer
Abstract
Atherosclerosis arises from disrupted cholesterol metabolism, notably impaired macrophage cholesterol efflux leading to foam cell formation. Through single-cell and bulk RNA sequencing, we identified Listerin as a regulator of macrophage cholesterol metabolism. Listerin expression increased during atherosclerosis progression in humans and rodents. Its deficiency suppressed cholesterol efflux, promoted foam cell formation, and exacerbated plaque features (macrophage infiltration, lipid deposition, necrotic cores) in macrophage-specific knockout mice. Conversely, Listerin overexpression attenuated these atherosclerotic manifestations. Mechanistically, Listerin stabilizes ABCA1, a key cholesterol efflux mediator, by catalyzing K63-linked polyubiquitination at residues K1884/K1957, countering ESCRT-mediated lysosomal degradation of ABCA1 induced by oxLDL. ABCA1 agonist Erythrodiol restored cholesterol efflux in Listerin-deficient macrophages, while ABCA1 knockout abolished Listerin's effects in THP-1 cells. This study establishes Listerin as a protective factor in atherosclerosis via post-translational stabilization of ABCA1, offering a potential therapeutic strategy targeting ABCA1 ubiquitination to enhance cholesterol efflux.
Authors
Lei Cao, Jie Zhang, Liwen Yu, Wei Yang, Wenqian Qi, Ruiqing Ren, Yapeng Liu, Yonghao Hou, Yu Cao, Qian Li, Xiaohong Wang, Zhengguo zhang, Bo Li, Wenhai Sui, Yun Zhang, Chengjiang Gao, Cheng Zhang, Meng Zhang
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)