Metabolism
Guanosine triphosphate links MYC-dependent metabolic and ribosome programs in small cell lung cancer
Abstract
MYC stimulates both metabolism and protein synthesis, but it is unknown how cells coordinate these complementary programs. Previous work reported that in a subset of small cell lung cancer (SCLC) cell lines, MYC activates guanosine triphosphate (GTP) synthesis and results in sensitivity to inhibitors of the GTP synthesis enzyme inosine monophosphate dehydrogenase (IMPDH). Here we demonstrated that primary MYCHigh human SCLC tumors also contain abundant guanosine nucleotides. We also found that elevated MYC in SCLCs with acquired chemoresistance rendered these otherwise recalcitrant tumors dependent on IMPDH. Unexpectedly, our data indicated that IMPDH links the metabolic and protein synthesis outputs of oncogenic MYC. Co-expression analysis placed IMPDH within the MYC-driven ribosome program, and GTP depletion prevented RNA Polymerase I (Pol I) from localizing to ribosomal DNA. Furthermore, the GTPases GPN1 and GPN3 were upregulated by MYC and directed Pol I to ribosomal DNA. Constitutively GTP-bound GPN1/3 mutants mitigated the effect of GTP depletion on Pol I, protecting chemoresistant SCLC cells from IMPDH inhibition. GTP therefore functions as a metabolic gate tethering MYC-dependent ribosome biogenesis to nucleotide sufficiency through GPN1 and GPN3. IMPDH dependence is a targetable vulnerability in chemoresistant, MYCHigh SCLC.
Authors
Fang Huang, Kenneth Huffman, Zixi Wang, Xun Wang, Kailong Li, Feng Cai, Chendong Yang, Ling Cai, Terry S. Shih, Lauren G. Zacharias, Andrew S. Chung, Qian Yang, Milind D. Chalishazar, Abbie S. Ireland, C. Allison Stewart, Kasey R. Cargill, Luc Girard, Yi Liu, Min Ni, Jian Xu, Xudong Wu, Hao Zhu, Benjamin J. Drapkin, Lauren A. Byers, Trudy G. Oliver, Adi Gazdar, John Minna, Ralph DeBerardinis
Abstract
A growing number of long non-coding RNAs (lncRNAs) have emerged as vital metabolic regulators. However, most human lncRNAs are non-conserved and highly tissue-specific, vastly limiting our ability to identify human lncRNA metabolic regulators (hLMRs). In this study, we establish a pipeline to identify putative hLMRs that are metabolically sensitive, disease-relevant, and population applicable. We first progressively processed multilevel human transcriptome data to select liver lncRNAs that exhibit highly dynamic expression in the general population, show differential expression in a nonalcoholic fatty liver disease (NAFLD) population, and response to dietary intervention in a small NAFLD cohort. We then experimentally demonstrated the responsiveness of selected hepatic lncRNAs to defined metabolic milieus in a liver-specific humanized mouse model. Furthermore, by extracting a concise list of protein-coding genes that are persistently correlated with lncRNAs in general and NAFLD populations, we predicted the specific function for each hLMR. Using gain- and loss-of-function approaches in humanized mice as well as ectopic expression in conventional mice, we validated the regulatory role of one non-conserved hLMR in cholesterol metabolism by coordinating with an RNA-binding protein, PTBP1, to modulate the transcription of cholesterol synthesis genes. Our work overcome the heterogeneity intrinsic to human data to enable the efficient identification and functional definition of disease-relevant human lncRNAs in metabolic homeostasis.
Authors
Xiangbo Ruan, Ping Li, Yonghe Ma, Chengfei Jiang, Yi Chen, Yu Shi, Nikhil Gupta, Fayaz Seifuddin, Mehdi Pirooznia, Yasuyuki Ohnishi, Nao Yoneda, Megumi Nishiwaki, Gabrijela Dumbovic, John L. Rinn, Yuichiro Higuchi, Kenji Kawai, Hiroshi Suemizu, Haiming Cao
Abstract
Obesity occurs when energy expenditure is outweighed by energy intake. Tuberal hypothalamic nuclei, including the arcuate nucleus (ARC), ventromedial nucleus (VMH), and dorsomedial nucleus (DMH), control for food intake and energy expenditure. Here we reported that, contrary to females, male mice lacking circadian nuclear receptors REV-ERB alpha and beta in the tuberal hypothalamus (HDKO) gained excessive weight on an obesogenic high fat diet due to both decreased energy expenditure and increased food intake during the light phase. Moreover, rebound food intake after fasting was markedly increased in HDKO mice. Integrative transcriptomic and cistromic analyses revealed that such disruption in feeding behavior was due to perturbed REV-ERB-dependent leptin signaling in the ARC. Indeed, in vivo leptin sensitivity was impaired in HDKO mice on an obesogenic diet in a diurnal manner. Thus, REV-ERBs play a crucial role in hypothalamic control of food intake and diurnal leptin sensitivity in diet-induced obesity.
Authors
Marine Adlanmerini, Hoang C. B. Nguyen, Brianna M. Krusen, Clare W. Teng, Caroline E. Geisler, Lindsey C. Peed, Bryce J. Carpenter, Matthew R. Hayes, Mitchell A. Lazar
Abstract
Dysfunction of primary cilia is related to dyshomeostasis, leading to a wide range of disorders. The ventromedial hypothalamus (VMH) is known to regulate several homeostatic processes, but those modulated specifically by VMH-primary cilia are not yet known. In this study, we identify VMH-primary cilia as an important organelle that maintains energy and skeletal homeostasis by modulating the autonomic nervous system. We established loss-of-function models of primary cilia in the VMH by either targeting IFT88 (IFT88 KOSF-1) using steroidogenic factor 1-Cre (SF1-Cre) or injecting an adeno-associated virus Cre (AAV-Cre) directly into the VMH. Functional impairments of VMH-primary cilia were linked to decreased sympathetic activation and central leptin resistance, which led to marked obesity and bone density accrual. Obesity was caused by hyperphagia, decreased energy expenditure, and blunted brown fat function, as well as associated with insulin and leptin resistance. The effect of bone density accrual was independent from obesity, as it was caused by the decreased sympathetic tone resulting in increased osteoblastic and decreased osteoclastic activities in the IFT88 KOSF-1 and VMH-primary cilia knock-down mice. Overall, our current study identifies VMH-primary cilia as a critical hypothalamic organelle that maintains energy and skeletal homeostasis.
Authors
Ji Su Sun, Dong Joo Yang, Ann W. Kinyua, Seul Gi Yoon, Je Kyung Seong, Juwon Kim, Seok Jun Moon, Dong Min Shin, Yun-Hee Choi, Ki Woo Kim
Abstract
Background. Clear cell renal cell carcinoma (ccRCC) is the most common histologically defined renal cancer. However, it is not a uniform disease and includes several genetic subtypes with different prognosis. ccRCC is also characterized by distinguished metabolic reprogramming. Tobacco smoking (TS) is an established risk factor for ccRCC with unknown effects on tumor pathobiology. Methods. We investigated the landscape of ccRCCs and paired normal kidney tissues (NKTs) using integrated transcriptomic, metabolomic and metallomic approaches in a cohort of never smokers (NS) and long-term current smokers (LTS) Caucasian males. Results. All three Omics domains consistentl identified a distinct metabolic subtype of ccRCCs in LTS, characterized by activation of oxidative phosphorylation (OxPhos) coupled with reprogramming of the malate-aspartate shuttle and metabolism of aspartate, glutamate, glutamine and histidine. Cadmium, copper and inorganic arsenic accumulated in LTS tumors showing redistribution among intracellular pools, including relocation of copper into the cytochrome c oxidase complex. Gene expression signature based on the LTS metabolic subtype provided prognostic stratification of The Cancer Genome Atlas (TCGA) ccRCC tumors that was independent from genomic alterations. Conclusions. The work identifies the TS related metabolic subtype of ccRCC with vulnerabilities that can be exploited for precision medicine approaches targeting metabolic pathways. The results provide rationale for the development of metabolic biomarkers with diagnostic and prognostic applications using evaluation of OxPhos status. The metallomic analysis reveals the role of disrupted metal homeostasis in ccRCC highlighting the importance of studying effects of metals from e-cigarettes and environmental exposures.
Authors
James Reigle, Dina Secic, Jacek Biesiada, Collin Wetzel, Behrouz Shamsaei, Johnson Chu, Yuanwei Zang, Xiang Zhang, Nicholas J. Talbot, Megan E. Bischoff, Yongzhen Zhang, Charuhas V. Thakar, Krishnanath Gaitonde, Abhinav Sidana, Hai Bui, John T. Cunningham, Qing Zhang, Laura S. Schmidt, W. Marston Linehan, Mario Medvedovic, David R. Plas, Julio A. Landero Figueroa, Jarek Meller, Maria F. Czyzyk-Krzeska
Abstract
RNA binding protein Apobec1 Complementation Factor (A1CF) regulates posttranscriptional ApoB mRNA editing but the range of RNA targets and long-term impact of altered A1CF expression on liver function are unknown. Here we studied hepatocyte-specific A1cf transgenic (A1cf +/Tg), A1cf+/Tg Apobec1–/– and A1cf –/– mice fed chow or high fat/high fructose diets using RNA-Seq, RNA-CLIP Seq and tissue microarrays from human hepatocellular cancer (HCC). A1cf +/Tg mice exhibited increased hepatic proliferation and steatosis, with increased lipogenic gene expression (Mogat1, Mogat2, Cidea, Cd36) associated with shifts in polysomal RNA distribution. Aged A1cf +/Tg mice developed spontaneous fibrosis, dysplasia and HCC, which was accelerated on a high fat/fructose diet and independent of Apobec1. RNA-Seq revealed increased expression of mRNAs involved in oxidative stress (Gstm3, Gpx3, Cbr3), inflammatory response (Il19, Cxcl14, Tnfα, Ly6c), extracellular matrix organization (Mmp2, Col1a1, Col4a1), proliferation (Kif20a, Mcm2, Mcm4, Mcm6) with a subset of mRNAs (including Sox4, Sox9, Cdh1) identified in RNA CLIP-Seq. Increased A1CF expression in human HCC correlated with advanced fibrosis and with reduced survival in a subset with nonalcoholic fatty liver disease. In conclusion, we show that hepatic A1CF overexpression selectively alters polysomal distribution and mRNA expression, promoting lipogenic, proliferative and inflammatory pathways leading to HCC.
Authors
Valerie Blanc, Jesse D. Riordan, Saeed Soleymanjahi, Joseph Nadeau, ILKe Nalbantoglu, Yan Xie, Elizabeth A. Molitor, Blair B. Madison, Elizabeth M. Brunt, Jason C. Mills, Deborah C. Rubin, Irene O.L. Ng, Yeonjung Ha, Lewis R. Roberts, Nicholas O. Davidson
Abstract
Particulate matter < 2.5 micrometers (PM2.5) air pollution is the world’s leading environmental risk factor contributing to mortality through cardiometabolic pathways. In this study, we modeled early life exposure using chow-fed C57BL/6J male mice, exposed to real-world inhaled concentrated PM2.5 (~10 times ambient levels / ~60-120ug/m3) or filtered air over 14 weeks. We investigated PM2.5 effects on phenotype, transcriptome and chromatin accessibility, compared the effects with a prototypical high-fat diet (HFD) stimulus, and examined cessation of exposure on reversibility of phenotype. Exposure to PM2.5 impaired glucose and insulin tolerance, reduced energy expenditure and 18FDG-PET uptake in brown adipose tissue. Multiple differentially expressed gene (DEG) clusters in pathways involving metabolism and circadian rhythm were noted in insulin responsive tissues. Although the magnitude of transcriptional change seen with PM2.5 was lower than HFD, the degree of alteration in chromatin accessibility after PM2.5 exposure was significant. A novel chromatin remodeler SMARCA5 (SWI/SNF complex) was regulated in response to PM2.5 with cessation of exposure associated with reversal of insulin resistance, restoration of chromatin accessibility/nucleosome positioning near transcription start sites (TSS) and exposure induced changes in the transcriptome including SMARCA5, indicating pliable epigenetic control mechanisms following exposure cessation.
Authors
Sanjay Rajagopalan, Bongsoo Park, Rengasamy Palanivel, Vinesh Vinayachandran, Jeffrey A. Deiuliis, Roopesh Singh Gangwar, Lopa M. Das, Jinhu Yin, Youngshim Choi, Sadeer Al-Kindi, Mukesh K. Jain, Kasper D. Hansen, Shyam Biswal
Abstract
Recent genome-wide association studies (GWAS) identified DUSP8, a dual-specificity phosphatase targeting MAP kinases, as type 2 diabetes (T2D) risk gene. Here, we unravel Dusp8 as gatekeeper in the hypothalamic control of glucose homeostasis in mice and humans. Male but not female Dusp8 loss-of-function mice, either with global or CRH neuron-specific deletion, had impaired systemic glucose tolerance and insulin sensitivity when exposed to high-fat diet (HFD). Mechanistically, we found impaired hypothalamic–pituitary–adrenal (HPA) axis feedback, blunted sympathetic responsiveness, and chronically elevated corticosterone levels driven by hypothalamic hyperactivation of Jnk signaling. Accordingly, global Jnk1 ablation, AAV-mediated Dusp8 overexpression in the mediobasal hypothalamus, or metyrapone-induced chemical adrenalectomy rescued the impaired glucose homeostasis of obese male Dusp8 KO mice, respectively. The sex-specific role of murine Dusp8 in governing hypothalamic Jnk signaling, insulin sensitivity and systemic glucose tolerance was consistent with fMRI data in human volunteers that revealed an association of the DUSP8 rs2334499 risk variant with hypothalamic insulin resistance in men. Further, expression of DUSP8 was increased in the infundibular nucleus of T2D humans. In summary, our findings suggest the GWAS-identified gene Dusp8 as novel hypothalamic factor that plays a functional role in the etiology of T2D.
Authors
Sonja C. Schriever, Dhiraj G. Kabra, Katrin Pfuhlmann, Peter Baumann, Emily V. Baumgart, Joachim Nagler, Fabian Seebacher, Luke Harrison, Martin Irmler, Stephanie Kullmann, Felipe Corrêa-da-Silva, Florian Giesert, Ruchi Jain, Hannah Schug, Julien Castel, Sarah Martinez, Moya Wu, Hans-Ulrich Häring, Martin Hrabe de Angelis, Johannes Beckers, Timo D. Müller, Kerstin Stemmer, Wolfgang Wurst, Jan Rozman, Rubén Nogueiras, Meri De Angelis, Jeffery D. Molkentin, Natalie Krahmer, Chun-Xia Yi, Mathias V. Schmidt, Serge Luquet, Martin Heni, Matthias H. Tschoep, Paul T. Pfluger
Abstract
Mitochondria have emerged as key actors of innate and adaptive immunity. Mitophagy has a pivotal role in cell homeostasis but its contribution to macrophage functions and host defense remains to be delineated. Here we showed that lipopolysaccharide (LPS) in combination with IFNγ, inhibits PINK1-dependent mitophagy in macrophages through a STAT1-dependent activation of the inflammatory caspases 1 and 11. In addition, we demonstrated that the inhibition of mitophagy triggers classical macrophage activation in a mitochondrial ROS-dependent manner. In a murine model of polymicrobial infection (cecal ligature and puncture, CLP), adoptive transfer of Pink1-deficient bone marrow or pharmacological inhibition of mitophagy promoted macrophage activation which favored bactericidal clearance and lead to a better survival. Reciprocally, mitochondrial uncouplers, that promote mitophagy, reverse LPS/IFNγ-mediated activation of macrophages and lead to immuno-paralysis with impaired bacterial clearance and lowered survival. In critically ill patients, we showed that mitophagy is inhibited in blood monocytes of patients with sepsis as compared to non-septic patients. Overall, this work demonstrates that the inhibition of mitophagy is a physiological mechanism that contributes to the activation of myeloid cells and improves the outcome of sepsis.
Authors
Danish Patoli, Franck Mignotte, Valérie Deckert, Alois Dusuel, Adelie Dumont, Aurelie Rieu, Antoine Jalil, Kevin Van Dongen, Thibaut Bourgeois, Thomas Gautier, Charlene Magnani, Naig Le Guern, Stéphane Mandard, Jean Bastin, Fatima Djouadi, Christine Schaeffer, Nina Guillaumot, Michel Narce, Maxime Nguyen, Julien Guy, Auguste Dargent, Jean-Pierre Quenot, Mickaël Rialland, David Masson, Johan Auwerx, Laurent Lagrost, Charles Thomas
Abstract
Males and females differ in body composition and fat distribution. Using a mouse model that segregates gonadal sex (ovaries and testes) from chromosomal sex (XX and XY), we showed that XX chromosome complement in combination with a high-fat diet led to enhanced weight gain in the presence of male or female gonads. We identified the genomic dosage of Kdm5c, an X chromosome gene that escapes X-chromosome inactivation, as a determinant of the X chromosome effect on adiposity. Modulating Kdm5c gene dosage in XX female mice to levels that are normally present in males reduced body weight, fat content, and food intake to a similar degree as altering the entire X chromosome dosage. In cultured preadipocytes, the levels of KDM5C histone demethylase influenced chromatin accessibility (ATAC-seq), gene expression (RNA-seq), and adipocyte differentiation. Both in vitro and in vivo, Kdm5c dosage influenced gene expression involved in extracellular matrix remodeling, which is critical for adipocyte differentiation and adipose tissue expansion. In humans, adipose tissue KDM5C mRNA levels and KDM5C genetic variants were associated with body mass. These studies demonstrate that the sex-dependent dosage of Kdm5c contributes to male/female differences in adipocyte biology, and highlight X-escape genes as a critical component of female physiology.
Authors
Jenny C. Link, Carrie B. Wiese, Xuqi Chen, Rozeta Avetisyan, Emilio Ronquillo, Feiyang Ma, Xiuqing Guo, Jie Yao, Matthew Allison, Yii-Der I. Chen, Jerome I. Rotter, Julia S. El-Sayed Moustafa, Kerrin S. Small, Shigeki Iwase, Matteo Pellegrini, Laurent Vergnes, Arthur P. Arnold, Karen Reue
Copyright © 2020 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)