Epigenetic status-altering mutations in chromatin-modifying enzymes are a feature of human diseases including many cancers. However, the functional outcomes and cellular dependencies arising from these mutations remain unresolved. In this study, we investigated cellular dependencies, or vulnerabilities, that arise when enhancer function is compromised by loss of the frequently mutated COMPASS family members MLL3 and MLL4. CRISPR dropout screens in MLL3/4-depleted mouse embryonic stem cells (mESCs) revealed synthetic lethality upon suppression of purine and pyrimidine nucleotide synthesis pathways. Consistently, we observed a shift in metabolic activity towards increased purine synthesis in MLL3/4 knockout (KO) mESCs. These cells also exhibited enhanced sensitivity to the purine synthesis inhibitor lometrexol, which induced a unique gene expression signature. RNA sequencing identified the top MLL3/4 target genes coinciding with suppression of purine metabolism, and tandem mass tag (TMT) proteomic profiling further confirmed upregulation of purine synthesis in MLL3/4 KO cells. Mechanistically, compensation by MLL1/COMPASS underlied these effects. Finally, we demonstrated that tumors with MLL3 and/or MLL4 mutations were highly sensitive to lometrexol in vivo, both in culture and in animal models of cancer. Our results depicted a targetable metabolic dependency arising from epigenetic factor deficiency, providing molecular insight to inform therapy for cancers with epigenetic alterations secondary to MLL3/4 COMPASS dysfunction.
Zibo Zhao, Kaixiang Cao, Jun Watanabe, Cassandra N. Philips, Jacob M. Zeidner, Yukitomo Ishi, Qixuan Wang, Sarah R. Gold, Katherine Junkins, Elizabeth T. Bartom, Feng Yue, Navdeep S. Chandel, Rintaro Hashizume, Issam Ben-Sahra, Ali Shilatifard
Deciphering the crosstalk between metabolic reprogramming and epigenetic regulation is a promising strategy for cancer therapy. In this study, we discovered that the gluconeogenic enzyme PCK1 fueled the generation of S-adenosylmethionine (SAM) through the serine synthesis pathway. The methyltransferase SUV39H1 catalyzed SAM, which served as a methyl donor to support H3K9me3 modification, leading to the suppression of the oncogene S100A11. Mechanistically, PCK1 deficiency-induced oncogenic activation of S100A11 was due to its interaction with AKT1, which upregulated PI3K/AKT signaling. Intriguingly, the progression of hepatocellular carcinoma (HCC) driven by PCK1 deficiency was suppressed by SAM supplement or S100A11 knockout in vivo and in vitro. These findings reveal the availability of key metabolite SAM as a bridge connecting the gluconeogenic enzyme PCK1 and H3K9 trimethylation in attenuating HCC progression, thus suggesting a potential therapeutic strategy against HCC.
Dongmei Gou, Rui Liu, Xiaoqun Shan, Haijun Deng, Chang Chen, Jin Xiang, Yi Liu, Qingzhu Gao, Zhi Li, Ailong Huang, Kai Wang, Ni Tang
Patients with Autosomal Recessive Microcephaly 15 caused by deficiency in the sodium-dependent lysophosphatidylcholine (LPC) transporter Major Facilitator Superfamily Domain containing 2a (Mfsd2a) present with both microcephaly and hypomyelination, suggesting an important role of LPC uptake by oligodendrocytes in the process of myelination. Here, we demonstrate that Mfsd2a is specifically expressed in oligodendrocyte precursor cells (OPC) and is critical for oligodendrocyte development. Single cell sequencing of the oligodendrocyte lineage revealed that OPCs from OPC-specific Mfsd2a KO mice (2aOKO) underwent precocious differentiation into immature oligodendrocytes (iOLs) and impaired maturation into myelinating oligodendrocytes, correlating with postnatal brain hypomyelination. 2aOKO mice did not exhibit microcephaly, consistent with microcephaly being consequential to absence of LPC uptake at the blood-brain barrier and not from deficiency in OPCs. Lipidomic analysis showed that OPCs and iOLs from 2aOKO mice had significantly decreased phospholipids containing omega-3 fatty acids with an opposite increase in unsaturated fatty acids, that latter being products of de novo synthesis governed by Srebp-1. RNA sequencing indicated activation of the Srebp-1 pathway and defective expression of regulators of oligodendrocyte development. Taken together, these findings indicate that the transport of LPCs by Mfsd2a in OPCs is important for maintaining OPC cell state to regulate postnatal brain myelination.
Vetrivel Sengottuvel, Monalisa Hota, Jeongah Oh, Dwight L. Galam, Bernice H. Wong, Markus R. Wenk, Sujoy Ghosh, Federico Torta, David L. Silver
Renal osteodystrophy (ROD) is a disorder of bone metabolism that affects virtually all patients with chronic kidney disease (CKD), and is associated with adverse clinical outcomes including fractures, cardiovascular events and death. In the present study, we showed that hepatocyte nuclear factor 4 alpha (HNF4α), a transcription factor mostly expressed in the liver, is also expressed in bone, and that osseous HNF4α expression was dramatically reduced in patients and mice with ROD. Osteoblast-specific deletion of Hnf4α resulted in impaired osteogenesis in cells and mice. Using multi-omics analyses of bones and cells lacking or overexpressing Hnf4α1 and Hnf4α2, we showed that HNF4α2 is the main osseous Hnf4α isoform that regulates osteogenesis, cell metabolism, and cell death. As a result, osteoblast-specific overexpression of Hnf4α2 prevented bone loss in mice with CKD. Our results showed that HNF4α2 is a transcriptional regulator of osteogenesis, implicated in the development of ROD.
Marta Martinez-Calle, Guillaume Courbon, Bridget Hunt-Tobey, Connor Francis, Jadeah J. Spindler, Xueyan Wang, Luciene M. dos Reis, Carolina Steller Wagner Martins, Isidro B. Salusky, Hartmut H. Malluche, Thomas L. Nickolas, Rosa M.A. Moyses, Aline Martin, Valentin David
Rhythmic intraorgan communication coordinates environmental signals and the cell-intrinsic clock to maintain organ homeostasis. Hepatocyte-specific KO of core components of the molecular clock Rev-erbα and -β (Reverb-hDKO) alters cholesterol and lipid metabolism in hepatocytes as well as rhythmic gene expression in nonparenchymal cells (NPCs) of the liver. Here, we report that in fatty liver caused by diet-induced obesity (DIO), hepatocyte SREBP cleavage–activating protein (SCAP) was required for Reverb-hDKO–induced diurnal rhythmic remodeling and epigenomic reprogramming in liver macrophages (LMs). Integrative analyses of isolated hepatocytes and LMs revealed that SCAP-dependent lipidomic changes in REV-ERB–depleted hepatocytes led to the enhancement of LM metabolic rhythms. Hepatocytic loss of REV-ERBα and β (REV-ERBs) also attenuated LM rhythms via SCAP-independent polypeptide secretion. These results shed light on the signaling mechanisms by which hepatocytes regulate diurnal rhythms in NPCs in fatty liver disease caused by DIO.
Dongyin Guan, Hosung Bae, Dishu Zhou, Ying Chen, Chunjie Jiang, Cam Mong La, Yang Xiao, Kun Zhu, Wenxiang Hu, Trang Minh Trinh, Panpan Liu, Ying Xiong, Bishuang Cai, Cholsoon Jang, Mitchell A. Lazar
Germline or somatic loss-of-function mutations of fumarate hydratase (FH) predispose patients to an aggressive form of renal cell carcinoma (RCC). Since other than tumor resection, there is no effective therapy for metastatic FH-deficient RCC, an accurate method for early diagnosis is needed. Although MRI or CT scans are offered, they cannot differentiate FH-deficient tumors from other RCCs. Therefore, finding noninvasive plasma biomarkers suitable for rapid diagnosis, screening and surveillance would improve clinical outcomes. Taking advantage of the robust metabolic rewiring that occurs in FH-deficient cells, we performed plasma metabolomics analysis and identified two tumor-derived metabolites, succinyl-adenosine and succinic-cysteine, as outstanding plasma biomarkers for early diagnosis (receiver operating characteristic area under curve (ROCAUC) = 0.98). These two molecules reliably reflected the FH mutation status and tumor mass. We further identified the enzymatic cooperativity by which these biomarkers are produced within the tumor microenvironment. Longitudinal monitoring of patients demonstrated that these circulating biomarkers can be used for reporting on treatment efficacy and identifying recurrent or metastatic tumors.
Liang Zheng, Zi-Ran Zhu, Tal Sneh, Weituo Zhang, Zao-Yu Wang, Guang-Yu Wu, Wei He, Hong-Gang Qi, Hang Wang, Xiao-Yu Wu, Jonatan Fernández-García, Ifat Abramovich, Yun-Ze Xu, Jin Zhang, Eyal Gottlieb
BACKGROUND. The stomach-derived hormone ghrelin stimulates appetite, but the ghrelin receptor is also expressed in brain circuits involved in motivation and reward. We examined ghrelin effects on decision making beyond food or drug rewards, using monetary outcomes. METHODS. Thirty participants (50% females) underwent two fMRI scans, in randomized counterbalanced order, while receiving intravenous ghrelin or saline. RESULTS. Striatal representations of reward anticipation were unaffected by ghrelin, while activity during anticipation of losses was attenuated. Temporal discounting rates of monetary rewards were lower overall in the ghrelin condition, an effect driven by women. Discounting rates were inversely correlated with neural activity in a large cluster within the left parietal lobule that included the angular gyrus. Activity in an overlapping cluster was related to behavioral choices, and was suppressed by ghrelin. CONCLUSION. This is to our knowledge the first human study to extend the understanding of ghrelin’s significance beyond the canonical feeding domain or in relation to addictive substances. Contrary to our hypothesis, we find that ghrelin does not affect sensitivity to monetary reward anticipation, but rather results in attenuated loss aversion and lower discounting rates for these rewards. Ghrelin may cause a motivational shift toward caloric rewards rather than globally promoting the value of rewards. TRIAL REGISTRATION. EudraCT 2018-004829-82 FUNDING. Swedish Research Council (MH: 2013-07434) and Marcus and Marianne Wallenberg foundation (GT: 2014.0187). Author LL is supported by NIDA/NIAAA IRP
Michal Pietrzak, Adam Yngve, J. Paul Hamilton, Robin Kämpe, Rebecca Boehme, Anna Asratian, Emelie Gauffin, Andreas Löfberg, Sarah Gustavson, Emil Persson, Andrea J. Capusan, Lorenzo Leggio, Irene Perini, Gustav Tinghög, Markus Heilig
Sphingolipids function as membrane constituents and signaling molecules, with crucial roles in human diseases, from neurodevelopmental to cancer, best exemplified in the inborn errors of sphingolipid metabolism in lysosomes. The dihydroceramide desaturase DEGS1 acts in the last step of a sector of the sphingolipid pathway, de novo ceramide biosynthesis. Defects in DEGS1 cause the recently described hypomyelinating leukodystrophy-18 (HLD18, OMIM #618404). Here, we reveal that DEGS1 is a mitochondria-associated endoplasmic reticulum membrane (MAM)-resident enzyme, refining previous reports locating DEGS1 at the endoplasmic reticulum only. Using patient fibroblasts, multi-omics and enzymatic assays, we show that DEGS1 deficiency disrupts the main core functions of the MAM: i) mitochondrial dynamics, with a hyperfused mitochondrial network associated with decreased activation of dynamin-related protein 1; ii) cholesterol metabolism, with impaired sterol O-acyltransferase activity and decreased cholesteryl esters; iii) phospholipid metabolism, with increased phosphatidic acid and phosphatidylserine and decreased phosphatidylethanolamine; iv) biogenesis of lipid droplets, with increased size and numbers. Moreover, we detected increased mitochondrial superoxide species production in fibroblasts and mitochondrial respiration impairment in patient muscle biopsy tissues. Our findings shed light on the pathophysiology of HLD18 and broaden our understanding of the role of sphingolipid metabolism in MAMs function.
Laura Planas-Serra, Nathalie Launay, Leire Goicoechea, Bénédicte Heron, Cristina Jou, Natalia Juliá-Palacios, Montserrat Ruiz, Stéphane Fourcade, Carlos Casasnovas, Carolina De La Torre, Antoinette Gelot, Maria Marsal, Pablo Loza-Alvarez, Àngels García-Cazorla, Ali Fatemi, Isidre Ferrer, Manuel Portero-Otin, Estela Area-Gómez, Aurora Pujol
Pathogens and inflammatory conditions rapidly induce the expression of immune-responsive gene 1 (IRG1) in cells of myeloid lineage. IRG1 encodes an aconitate decarboxylase (ACOD1) that produces the immunomodulatory metabolite itaconate (ITA). In addition to rapid intracellular accumulation, ITA is also secreted from the cell, but whether secreted ITA functions as a signaling molecule is unclear. Here, we identified ITA as an orthosteric agonist of the GPCR OXGR1, with an EC50 of approximately 0.3 mM, which was in the same range as the physiological concentration of extracellular ITA upon macrophage activation. ITA activated OXGR1 to induce Ca2+ mobilization, ERK phosphorylation, and endocytosis of the receptor. In a mouse model of pulmonary infection with bacterial Pseudomonas aeruginosa, ITA stimulated Oxgr1-dependent mucus secretion and transport in respiratory epithelium, the primary innate defense mechanism of the airway. Our study thus identifies ITA as a bona fide ligand for OXGR1 and the ITA/OXGR1 paracrine signaling pathway during the pulmonary innate immune response.
Yi-Rong Zeng, Jun-Bin Song, Dezheng Wang, Zi-Xuan Huang, Cheng Zhang, Yi-Ping Sun, Gang Shu, Yue Xiong, Kun-Liang Guan, Dan Ye, Pu Wang
Activation of STING signaling in dendritic cells (DCs) promotes antitumor immunity. Aerobic glycolysis is a metabolic hallmark of activated DCs, but how the glycolytic pathway intersects with STING signaling in tumor-infiltrating DCs remains elusive. Here, we show that glycolysis drives STING signaling to facilitate DC-mediated antitumor immune responses. Tumor-infiltrating DCs exhibited elevated glycolysis, and blockade of glycolysis by DC-specific Ldha/Ldhb double deletion resulted in defective antitumor immunity. Mechanistically, glycolysis augmented ATP production to boost STING activation and STING-dependent DC antitumor functions. Moreover, DC-intrinsic STING activation accelerated HIF-1a–mediated glycolysis and established a positive feedback loop. Importantly, glycolysis facilitated STING-dependent DC activity in tissue samples from non-small cell lung cancer patients. Our results provide mechanistic insight into how the crosstalk of glycolytic metabolism and STING signaling enhances DC antitumor activity and can be harnessed to improve cancer therapies.
Zhilin Hu, Xiaoyan Yu, Rui Ding, Ben Liu, Chuanjia Gu, Xiu-Wu Pan, Qiaoqiao Han, Yuerong Zhang, Jie Wan, Xin-gang Cui, Jiayuan Sun, Qiang Zou