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Feng R, Liu F, Li R, Zhou Z, Lin Z, Lin S, Deng S, Li Y, Nong B, Xia Y, Li Z, Zhong X, Yang S, Wan G, Ma W, Wu S, Songyang Z. The rapid proximity labeling system PhastID identifies ATP6AP1 as an unconventional GEF for Rheb. Cell Res 2024; 34:355-369. [PMID: 38448650 PMCID: PMC11061317 DOI: 10.1038/s41422-024-00938-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 02/02/2024] [Indexed: 03/08/2024] Open
Abstract
Rheb is a small G protein that functions as the direct activator of the mechanistic target of rapamycin complex 1 (mTORC1) to coordinate signaling cascades in response to nutrients and growth factors. Despite extensive studies, the guanine nucleotide exchange factor (GEF) that directly activates Rheb remains unclear, at least in part due to the dynamic and transient nature of protein-protein interactions (PPIs) that are the hallmarks of signal transduction. Here, we report the development of a rapid and robust proximity labeling system named Pyrococcus horikoshii biotin protein ligase (PhBPL)-assisted biotin identification (PhastID) and detail the insulin-stimulated changes in Rheb-proximity protein networks that were identified using PhastID. In particular, we found that the lysosomal V-ATPase subunit ATP6AP1 could dynamically interact with Rheb. ATP6AP1 could directly bind to Rheb through its last 12 amino acids and utilizes a tri-aspartate motif in its highly conserved C-tail to enhance Rheb GTP loading. In fact, targeting the ATP6AP1 C-tail could block Rheb activation and inhibit cancer cell proliferation and migration. Our findings highlight the versatility of PhastID in mapping transient PPIs in live cells, reveal ATP6AP1's role as an unconventional GEF for Rheb, and underscore the importance of ATP6AP1 in integrating mTORC1 activation signals through Rheb, filling in the missing link in Rheb/mTORC1 activation.
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Affiliation(s)
- Ran Feng
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Feng Liu
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China.
| | - Ruofei Li
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Zhifen Zhou
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Zhuoheng Lin
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Song Lin
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Shengcheng Deng
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yingying Li
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Baoting Nong
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Ying Xia
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Zhiyi Li
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xiaoqin Zhong
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Shuhan Yang
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Gang Wan
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wenbin Ma
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Su Wu
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
| | - Zhou Songyang
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, School of Life Sciences, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou, Guangdong, China.
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
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Uranbileg B, Kurano M, Kano K, Sakai E, Arita J, Hasegawa K, Nishikawa T, Ishihara S, Yamashita H, Seto Y, Ikeda H, Aoki J, Yatomi Y. Sphingosine 1-phosphate lyase facilitates cancer progression through converting sphingolipids to glycerophospholipids. Clin Transl Med 2022; 12:e1056. [PMID: 36125914 PMCID: PMC9488530 DOI: 10.1002/ctm2.1056] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 08/23/2022] [Accepted: 08/29/2022] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND In addition to potent agonist properties for sphingosine 1-phosphate (S1P) receptors, intracellularly, S1P is an intermediate in metabolic conversion pathway from sphingolipids to glycerolysophospholipids (glyceroLPLs). We hypothesized that this S1P metabolism and its products might possess some novel roles in the pathogenesis of cancer, where S1P lyase (SPL) is a key enzyme. METHODS The mRNA levels of sphingolipid-related and other cancer-related factors were measured in human hepatocellular carcinoma (HCC), colorectal cancer, and esophageal cancer patients' tumours and in their adjacent non-tumour tissues. Phospholipids (PL) and glyceroLPLs were measured by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In-vitro experiments were performed in Colon 26 cell line with modulation of the SPL and GPR55 expressions. Xenograft model was used for determination of the cancer progression and for pharmacological influence. RESULTS Besides high SPL levels in human HCC and colon cancer, SPL levels were specifically and positively linked with levels of glyceroLPLs, including lysophosphatidylinositol (LPI). Overexpression of SPL in Colon 26 cells resulted in elevated levels of LPI and lysophosphatidylglycerol (LPG), which are agonists of GPR55. SPL overexpression-enhanced cell proliferation was inhibited by GPR55 silencing. Conversely, inhibition of SPL led to the opposite outcome and reversed by adding LPI, LPG, and metabolites generated during S1P degradation, which is regulated by SPL. The xenograft model results suggested the contribution of SPL and glyceroLPLs to tumour progression depending on levels of SPL and GPR55. Moreover, the pharmacological inhibition of SPL prevented the progression of cancer. The underlying mechanisms for the SPL-mediated cancer progression are the activation of p38 and mitochondrial function through the LPI, LPG-GPR55 axis and the suppression of autophagy in a GPR55-independent manner. CONCLUSION A new metabolic pathway has been proposed here in HCC and colon cancer, SPL converts S1P to glyceroLPLs, mainly to LPI and LPG, and facilitates cancer development.
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Affiliation(s)
- Baasanjav Uranbileg
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Makoto Kurano
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kuniyuki Kano
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Eri Sakai
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Junichi Arita
- Hepato-Biliary-Pancreatic Surgery Division, Department of Surgery, The University of Tokyo, Tokyo, Japan
| | - Kiyoshi Hasegawa
- Hepato-Biliary-Pancreatic Surgery Division, Department of Surgery, The University of Tokyo, Tokyo, Japan
| | - Takeshi Nishikawa
- Surgical Oncology and Vascular Surgery Division, Department of Surgery, The University of Tokyo, Tokyo, Japan
| | - Soichiro Ishihara
- Surgical Oncology and Vascular Surgery Division, Department of Surgery, The University of Tokyo, Tokyo, Japan
| | - Hiroharu Yamashita
- Gastrointestinal Surgery Division, Department of Surgery, The University of Tokyo, Tokyo, Japan.,Division of Digestive Surgery, Department of Surgery, Nihon University School of Medicine, Tokyo, Japan
| | - Yasuyuki Seto
- Gastrointestinal Surgery Division, Department of Surgery, The University of Tokyo, Tokyo, Japan
| | - Hitoshi Ikeda
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Junken Aoki
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Yutaka Yatomi
- Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Li S, Kim HE. Implications of Sphingolipids on Aging and Age-Related Diseases. FRONTIERS IN AGING 2022; 2:797320. [PMID: 35822041 PMCID: PMC9261390 DOI: 10.3389/fragi.2021.797320] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 12/31/2021] [Indexed: 01/14/2023]
Abstract
Aging is a process leading to a progressive loss of physiological integrity and homeostasis, and a primary risk factor for many late-onset chronic diseases. The mechanisms underlying aging have long piqued the curiosity of scientists. However, the idea that aging is a biological process susceptible to genetic manipulation was not well established until the discovery that the inhibition of insulin/IGF-1 signaling extended the lifespan of C. elegans. Although aging is a complex multisystem process, López-Otín et al. described aging in reference to nine hallmarks of aging. These nine hallmarks include: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. Due to recent advances in lipidomic, investigation into the role of lipids in biological aging has intensified, particularly the role of sphingolipids (SL). SLs are a diverse group of lipids originating from the Endoplasmic Reticulum (ER) and can be modified to create a vastly diverse group of bioactive metabolites that regulate almost every major cellular process, including cell cycle regulation, senescence, proliferation, and apoptosis. Although SL biology reaches all nine hallmarks of aging, its contribution to each hallmark is disproportionate. In this review, we will discuss in detail the major contributions of SLs to the hallmarks of aging and age-related diseases while also summarizing the importance of their other minor but integral contributions.
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Affiliation(s)
- Shengxin Li
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, TX, United States
- Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Hyun-Eui Kim
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, TX, United States
- Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center, Houston, TX, United States
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4
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Jiménez-Uribe AP, Gómez-Sierra T, Aparicio-Trejo OE, Orozco-Ibarra M, Pedraza-Chaverri J. Backstage players of fibrosis: NOX4, mTOR, HDAC, and S1P; companions of TGF-β. Cell Signal 2021; 87:110123. [PMID: 34438016 DOI: 10.1016/j.cellsig.2021.110123] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/19/2021] [Accepted: 08/20/2021] [Indexed: 12/16/2022]
Abstract
The fibrotic process could be easily defined as a pathological excess of extracellular matrix deposition, leading to disruption of tissue architecture and eventually loss of function; however, this process involves a complex network of several signal transduction pathways. Virtually almost all organs could be affected by fibrosis, the most affected are the liver, lung, skin, kidney, heart, and eyes; in all of them, the transforming growth factor-beta (TGF-β) has a central role. The canonical and non-canonical signal pathways of TGF-β impact the fibrotic process at the cellular and molecular levels, inducing the epithelial-mesenchymal transition (EMT) and the induction of profibrotic gene expression with the consequent increase in proteins such as alpha-smooth actin (α-SMA), fibronectin, collagen, and other extracellular matrix proteins. Recently, it has been reported that some molecules that have not been typically associated with the fibrotic process, such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4), mammalian target of rapamycin (mTOR), histone deacetylases (HDAC), and sphingosine-1 phosphate (S1P); are critical in its development. In this review, we describe and discuss the role of these new players of fibrosis and the convergence with TGF-β signaling pathways, unveiling new insights into the panorama of fibrosis that could be useful for future therapeutic targets.
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Affiliation(s)
| | - Tania Gómez-Sierra
- Facultad de Química, Departamento de Biología, Universidad Nacional Autónoma de México, CDMX 04510, Mexico
| | - Omar Emiliano Aparicio-Trejo
- Departamento de Fisiopatología Cardio-Renal, Instituto Nacional de Cardiología "Ignacio Chávez", Mexico City 14080, Mexico
| | - Marisol Orozco-Ibarra
- Laboratorio de Neurobiología Molecular y Celular, Instituto Nacional de Neurología y Neurocirugía, Manuel Velasco Suárez, Av. Insurgentes Sur # 3877, La Fama, Alcaldía Tlalpan, CP 14269 Ciudad de México, Mexico
| | - José Pedraza-Chaverri
- Facultad de Química, Departamento de Biología, Universidad Nacional Autónoma de México, CDMX 04510, Mexico.
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5
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Poczobutt JM, Mikosz AM, Poirier C, Beatman EL, Serban KA, Gally F, Cao D, McCubbrey AL, Cornell CF, Schweitzer KS, Berdyshev EV, Bronova IA, Paris F, Petrache I. Altered Macrophage Function Associated with Crystalline Lung Inflammation in Acid Sphingomyelinase Deficiency. Am J Respir Cell Mol Biol 2021; 64:629-640. [PMID: 33662226 DOI: 10.1165/rcmb.2020-0229oc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Deficiency of ASM (acid sphingomyelinase) causes the lysosomal storage Niemann-Pick disease (NPD). Patients with NPD type B may develop progressive interstitial lung disease with frequent respiratory infections. Although several investigations using the ASM-deficient (ASMKO) mouse NPD model revealed inflammation and foamy macrophages, there is little insight into the pathogenesis of NPD-associated lung disease. Using ASMKO mice, we report that ASM deficiency is associated with a complex inflammatory phenotype characterized by marked accumulation of monocyte-derived CD11b+ macrophages and expansion of airspace/alveolar CD11c+ CD11b- macrophages, both with increased size, granularity, and foaminess. Both the alternative and classical pathways were activated, with decreased in situ phagocytosis of opsonized (Fc-coated) targets, preserved clearance of apoptotic cells (efferocytosis), secretion of Th2 cytokines, increased CD11c+/CD11b+ cells, and more than a twofold increase in lung and plasma proinflammatory cytokines. Macrophages, neutrophils, eosinophils, and noninflammatory lung cells of ASMKO lungs also exhibited marked accumulation of chitinase-like protein Ym1/2, which formed large eosinophilic polygonal Charcot-Leyden-like crystals. In addition to providing insight into novel features of lung inflammation that may be associated with NPD, our report provides a novel connection between ASM and the development of crystal-associated lung inflammation with alterations in macrophage biology.
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Affiliation(s)
| | | | | | | | - Karina A Serban
- National Jewish Health, Denver, Colorado.,University of Colorado, Denver, Colorado
| | - Fabienne Gally
- National Jewish Health, Denver, Colorado.,University of Colorado, Denver, Colorado
| | | | | | | | - Kelly S Schweitzer
- National Jewish Health, Denver, Colorado.,University of Colorado, Denver, Colorado
| | | | | | - François Paris
- Institut de Cancérologie de l'Ouest, Saint-Herblain, France; and.,Le Regional Center for Research in Cancerology and Immunology Nantes/Angers, Université de Nantes, Nantes, France
| | - Irina Petrache
- National Jewish Health, Denver, Colorado.,Indiana University, Indianapolis, Indiana.,University of Colorado, Denver, Colorado
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Tegeder I, Kögel D. When lipid homeostasis runs havoc: Lipotoxicity links lysosomal dysfunction to autophagy. Matrix Biol 2021; 100-101:99-117. [DOI: 10.1016/j.matbio.2020.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/29/2020] [Accepted: 11/30/2020] [Indexed: 02/07/2023]
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7
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Sun H, Zhou Z, Dong Y, Yang A, Jiang J. Insights into the DNA methylation of sea cucumber Apostichopus japonicus in response to skin ulceration syndrome infection. FISH & SHELLFISH IMMUNOLOGY 2020; 104:155-164. [PMID: 32502611 DOI: 10.1016/j.fsi.2020.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 03/23/2020] [Accepted: 05/02/2020] [Indexed: 06/11/2023]
Abstract
DNA methylation is an important epigenetic modification that regulates gene expression in many biological processes, including immune response. In this study, whole-genome bisulfite sequencing (WGBS) was carried out on healthy body wall (HB) and skin ulceration syndrome (SUS) infected body wall (SFB) to gain insights into the epigenetic regulatory mechanism in sea cucumber Apostichopus japonicus. After comparison, a total of 116,522 differentially methylated regions (DMRs) were obtained including 67,269 hyper-methylated and 49,253 hypo-methylated DMRs (p < 0.05, FDR < 0.001). GO enrichment analysis indicated that regulation of DNA-templated transcription (GO: 0006355), where DNA methylation occurred, was the most significant term in the biology process. The integration of methylome and transcriptome analysis revealed that 10,499 DMRs were negatively correlated with 496 differentially expressed genes (DEGs). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that these DEGs were enriched in the phosphoinositide 3-kinase-protein kinase B (PI3K/Akt)/mammalian target of rapamycin (mTOR) signaling pathway. Interestingly, two serine/threonine-protein kinases, nemo-like kinase (NLK) and mTOR, were highlighted after functional analysis. The variations of methylation in these two genes were associated with SUS infection and immune regulation. They regulated gene expression at different levels and showed interaction during response process. The validation of methylation sites showed high consistency between pyrosequencing and WGBS. WGBS analysis not only revealed the changes of DNA methylation, but also presented important information about the regulation of key genes after SUS infection in A. japonicus.
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Affiliation(s)
- Hongjuan Sun
- Liaoning Key Lab of Marine Fishery Molecular Biology, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Zunchun Zhou
- Liaoning Key Lab of Marine Fishery Molecular Biology, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China.
| | - Ying Dong
- Liaoning Key Lab of Marine Fishery Molecular Biology, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Aifu Yang
- Liaoning Key Lab of Marine Fishery Molecular Biology, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Jingwei Jiang
- Liaoning Key Lab of Marine Fishery Molecular Biology, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
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8
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Abstract
A complex molecular machinery converges on the surface of lysosomes to ensure that the growth-promoting signaling mediated by mechanistic target of rapamycin complex 1 (mTORC1) is tightly controlled by the availability of nutrients and growth factors. The final step in this activation process is dependent on Rheb, a small GTPase that binds to mTOR and allosterically activates its kinase activity. Here we review the mechanisms that determine the subcellular localization of Rheb (and the closely related RhebL1 protein) as well as the significance of these mechanisms for controlling mTORC1 activation. In particular, we explore how the relatively weak membrane interactions conferred by C-terminal farnesylation are critical for the ability of Rheb to activate mTORC1. In addition to supporting transient membrane interactions, Rheb C-terminal farnesylation also supports an interaction between Rheb and the δ subunit of phosphodiesterase 6 (PDEδ). This interaction provides a potential mechanism for targeting Rheb to membranes that contain Arl2, a small GTPase that triggers the release of prenylated proteins from PDEδ. The minimal membrane targeting conferred by C-terminal farnesylation of Rheb and RhebL1 distinguishes them from other members of the Ras superfamily that possess additional membrane interaction motifs that work with farnesylation for enrichment on the specific subcellular membranes where they engage key effectors. Finally, we highlight diversity in Rheb membrane targeting mechanisms as well as the potential for alternative mTORC1 activation mechanisms across species.
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Affiliation(s)
- Brittany Angarola
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, 06510, USA.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT, 06510, USA
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Combined Omics Approach Identifies Gambogic Acid and Related Xanthones as Covalent Inhibitors of the Serine Palmitoyltransferase Complex. Cell Chem Biol 2020; 27:586-597.e12. [DOI: 10.1016/j.chembiol.2020.03.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 02/19/2020] [Accepted: 03/09/2020] [Indexed: 02/08/2023]
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10
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Chi F, Sharpley MS, Nagaraj R, Roy SS, Banerjee U. Glycolysis-Independent Glucose Metabolism Distinguishes TE from ICM Fate during Mammalian Embryogenesis. Dev Cell 2020; 53:9-26.e4. [PMID: 32197068 DOI: 10.1016/j.devcel.2020.02.015] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/26/2019] [Accepted: 02/19/2020] [Indexed: 01/01/2023]
Abstract
The mouse embryo undergoes compaction at the 8-cell stage, and its transition to 16 cells generates polarity such that the outer apical cells are trophectoderm (TE) precursors and the inner cell mass (ICM) gives rise to the embryo. Here, we report that this first cell fate specification event is controlled by glucose. Glucose does not fuel mitochondrial ATP generation, and glycolysis is dispensable for blastocyst formation. Furthermore, glucose does not help synthesize amino acids, fatty acids, and nucleobases. Instead, glucose metabolized by the hexosamine biosynthetic pathway (HBP) allows nuclear localization of YAP1. In addition, glucose-dependent nucleotide synthesis by the pentose phosphate pathway (PPP), along with sphingolipid (S1P) signaling, activates mTOR and allows translation of Tfap2c. YAP1, TEAD4, and TFAP2C interact to form a complex that controls TE-specific gene transcription. Glucose signaling has no role in ICM specification, and this process of developmental metabolism specifically controls TE cell fate.
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Affiliation(s)
- Fangtao Chi
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Mark S Sharpley
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Raghavendra Nagaraj
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Shubhendu Sen Roy
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Utpal Banerjee
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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11
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Transcriptional Regulation of Genes by Ikaros Tumor Suppressor in Acute Lymphoblastic Leukemia. Int J Mol Sci 2020; 21:ijms21041377. [PMID: 32085659 PMCID: PMC7073093 DOI: 10.3390/ijms21041377] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 02/13/2020] [Accepted: 02/14/2020] [Indexed: 12/27/2022] Open
Abstract
Regulation of oncogenic gene expression by transcription factors that function as tumor suppressors is one of the major mechanisms that regulate leukemogenesis. Understanding this complex process is essential for explaining the pathogenesis of leukemia as well as developing targeted therapies. Here, we provide an overview of the role of Ikaros tumor suppressor and its role in regulation of gene transcription in acute leukemia. Ikaros (IKZF1) is a DNA-binding protein that functions as a master regulator of hematopoiesis and the immune system, as well as a tumor suppressor in acute lymphoblastic leukemia (ALL). Genetic alteration or functional inactivation of Ikaros results in the development of high-risk leukemia. Ikaros binds to the specific consensus binding motif at upstream regulatory elements of its target genes, recruits chromatin-remodeling complexes and activates or represses transcription via chromatin remodeling. Over the last twenty years, a large number of Ikaros target genes have been identified, and the role of Ikaros in the regulation of their expression provided insight into the mechanisms of Ikaros tumor suppressor function in leukemia. Here we summarize the role of Ikaros in the regulation of the expression of the genes whose function is critical for cellular proliferation, development, and progression of acute lymphoblastic leukemia.
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12
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Zhu J, Tsai NP. Ubiquitination and E3 Ubiquitin Ligases in Rare Neurological Diseases with Comorbid Epilepsy. Neuroscience 2020; 428:90-99. [DOI: 10.1016/j.neuroscience.2019.12.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 12/19/2022]
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13
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CD69 Targeting Enhances Anti-vaccinia Virus Immunity. J Virol 2019; 93:JVI.00553-19. [PMID: 31315995 DOI: 10.1128/jvi.00553-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/07/2019] [Indexed: 12/30/2022] Open
Abstract
CD69 is highly expressed on the leukocyte surface upon viral infection, and its regulatory role in the vaccinia virus (VACV) immune response has been recently demonstrated using CD69-/- mice. Here, we show augmented control of VACV infection using the anti-human CD69 monoclonal antibody (MAb) 2.8 as both preventive and therapeutic treatment for mice expressing human CD69. This control was related to increased natural killer (NK) cell reactivity and increased numbers of cytokine-producing T and NK cells in the periphery. Moreover, similarly increased immunity and protection against VACV were reproduced over both long and short periods in anti-mouse CD69 MAb 2.2-treated immunocompetent wild-type (WT) mice and immunodeficient Rag2-/- CD69+/+ mice. This result was not due to synergy between infection and anti-CD69 treatment since, in the absence of infection, anti-human CD69 targeting induced immune activation, which was characterized by mobilization, proliferation, and enhanced survival of immune cells as well as marked production of several innate proinflammatory cytokines by immune cells. Additionally, we showed that the rapid leukocyte effect induced by anti-CD69 MAb treatment was dependent on mTOR signaling. These properties suggest the potential of CD69-targeted therapy as an antiviral adjuvant to prevent derived infections.IMPORTANCE In this study, we demonstrate the influence of human and mouse anti-CD69 therapies on the immune response to VACV infection. We report that targeting CD69 increases the leukocyte numbers in the secondary lymphoid organs during infection and improves the capacity to clear the viral infection. Targeting CD69 increases the numbers of gamma interferon (IFN-γ)- and tumor necrosis factor alpha (TNF-α)-producing NK and T cells. In mice expressing human CD69, treatment with an anti-CD69 MAb produces increases in cytokine production, survival, and proliferation mediated in part by mTOR signaling. These results, together with the fact that we have mainly worked with a human-CD69 transgenic model, reveal CD69 as a treatment target to enhance vaccine protectiveness.
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Jęśko H, Stępień A, Lukiw WJ, Strosznajder RP. The Cross-Talk Between Sphingolipids and Insulin-Like Growth Factor Signaling: Significance for Aging and Neurodegeneration. Mol Neurobiol 2019; 56:3501-3521. [PMID: 30140974 PMCID: PMC6476865 DOI: 10.1007/s12035-018-1286-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 07/25/2018] [Indexed: 12/20/2022]
Abstract
Bioactive sphingolipids: sphingosine, sphingosine-1-phosphate (S1P), ceramide, and ceramide-1-phosphate (C1P) are increasingly implicated in cell survival, proliferation, differentiation, and in multiple aspects of stress response in the nervous system. The opposite roles of closely related sphingolipid species in cell survival/death signaling is reflected in the concept of tightly controlled sphingolipid rheostat. Aging has a complex influence on sphingolipid metabolism, disturbing signaling pathways and the properties of lipid membranes. A metabolic signature of stress resistance-associated sphingolipids correlates with longevity in humans. Moreover, accumulating evidence suggests extensive links between sphingolipid signaling and the insulin-like growth factor I (IGF-I)-Akt-mTOR pathway (IIS), which is involved in the modulation of aging process and longevity. IIS integrates a wide array of metabolic signals, cross-talks with p53, nuclear factor κB (NF-κB), or reactive oxygen species (ROS) and influences gene expression to shape the cellular metabolic profile and stress resistance. The multiple connections between sphingolipids and IIS signaling suggest possible engagement of these compounds in the aging process itself, which creates a vulnerable background for the majority of neurodegenerative disorders.
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Affiliation(s)
- Henryk Jęśko
- Department of Cellular Signalling, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Pawińskiego, 5, 02-106, Poland
| | - Adam Stępień
- Central Clinical Hospital of the Ministry of National Defense, Department of Neurology, Military Institute of Medicine, Warsaw, Szaserów, 128, 04-141, Poland
| | - Walter J Lukiw
- LSU Neuroscience Center and Departments of Neurology and Ophthalmology, Louisiana State University School of Medicine, New Orleans, USA
| | - Robert P Strosznajder
- Laboratory of Preclinical Research and Environmental Agents, Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Pawińskiego, 5, 02-106, Poland.
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15
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Mitroi DN, Karunakaran I, Gräler M, Saba JD, Ehninger D, Ledesma MD, van Echten-Deckert G. SGPL1 (sphingosine phosphate lyase 1) modulates neuronal autophagy via phosphatidylethanolamine production. Autophagy 2018; 13:885-899. [PMID: 28521611 PMCID: PMC5446076 DOI: 10.1080/15548627.2017.1291471] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Macroautophagy/autophagy defects have been identified as critical factors underlying the pathogenesis of neurodegenerative diseases. The roles of the bioactive signaling lipid sphingosine-1-phosphate (S1P) and its catabolic enzyme SGPL1/SPL (sphingosine phosphate lyase 1) in autophagy are increasingly recognized. Here we provide in vitro and in vivo evidence for a previously unidentified route through which SGPL1 modulates autophagy in neurons. SGPL1 cleaves S1P into ethanolamine phosphate, which is directed toward the synthesis of phosphatidylethanolamine (PE) that anchors LC3-I to phagophore membranes in the form of LC3-II. In the brains of SGPL1fl/fl/Nes mice with developmental neural specific SGPL1 ablation, we observed significantly reduced PE levels. Accordingly, alterations in basal and stimulated autophagy involving decreased conversion of LC3-I to LC3-II and increased BECN1/Beclin-1 and SQSTM1/p62 levels were apparent. Alterations were also noticed in downstream events of the autophagic-lysosomal pathway such as increased levels of lysosomal markers and aggregate-prone proteins such as APP (amyloid β [A4] precursor protein) and SNCA/α-synuclein. In vivo profound deficits in cognitive skills were observed. Genetic and pharmacological inhibition of SGPL1 in cultured neurons promoted these alterations, whereas addition of PE was sufficient to restore LC3-I to LC3-II conversion, and control levels of SQSTM1, APP and SNCA. Electron and immunofluorescence microscopy showed accumulation of unclosed phagophore-like structures, reduction of autolysosomes and altered distribution of LC3 in SGPL1fl/fl/Nes brains. Experiments using EGFP-mRFP-LC3 provided further support for blockage of the autophagic flux at initiation stages upon SGPL1 deficiency due to PE paucity. These results emphasize a formerly overlooked direct role of SGPL1 in neuronal autophagy and assume significance in the context that autophagy modulators hold an enormous therapeutic potential in the treatment of neurodegenerative diseases.
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Affiliation(s)
- Daniel N Mitroi
- a LIMES Institute, Membrane Biology and Lipid Biochemistry, University of Bonn , Bonn , Germany
| | - Indulekha Karunakaran
- a LIMES Institute, Membrane Biology and Lipid Biochemistry, University of Bonn , Bonn , Germany
| | - Markus Gräler
- b Department of Anesthesiology and Intensive Care Medicine , Center for Sepsis Control and Care (CSCC), and the Center for Molecular Biomedicine (CMB), University Hospital Jena , Jena , Germany
| | - Julie D Saba
- c Children's Hospital Oakland Research Institute, University of California , San Francisco , CA , USA
| | - Dan Ehninger
- d German Centre for Neurodegenerative Diseases (DZNE) , Bonn , Germany
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16
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Anti-CD69 therapy induces rapid mobilization and high proliferation of HSPCs through S1P and mTOR. Leukemia 2018; 32:1445-1457. [PMID: 29483712 DOI: 10.1038/s41375-018-0052-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 12/30/2017] [Accepted: 01/11/2018] [Indexed: 01/05/2023]
Abstract
CD69 regulates lymphocyte egress from the thymus and lymph nodes through cis-interactions and the downregulation of surface sphingosine-1-phosphate (S1P) receptor-1 (S1P1). However, its role in the regulation of cell egress from bone marrow has not been extensively studied. We show here that CD69 targeting induced rapid and massive mobilization of BM leukocytes, which was inhibited by desensitization to S1P with FTY720. This mobilization was reproduced with anti-human CD69 mAb treatment of mice expressing human CD69. In this strain, the mobilization occurred to the same extent as that induced by AMD3100. The anti-human CD69 treatment highly increased LSK and CLP cell proliferation and numbers, both in the periphery and in the BM, and also augmented S1P1 and CXCR4 expression. Additionally, increased mTOR, p70S6K, S6, and 4E-BP1 phosphorylation was detected after in vivo anti-CD69 treatment in the bone marrow. Importantly, mTOR inhibition with rapamycin inhibited anti-huCD69-induced mobilization of hematopoietic stem and progenitor cells (HSPCs). Together, our results indicated that CD69 targeting induces not only mobilization but also high proliferation of HSPCs, and thus is crucial for precursor cell replenishment over time. These results suggest that anti-CD69 mAbs are putative novel candidates for mobilization strategies.
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Li X, Wang MH, Qin C, Fan WH, Tian DS, Liu JL. Fingolimod suppresses neuronal autophagy through the mTOR/p70S6K pathway and alleviates ischemic brain damage in mice. PLoS One 2017; 12:e0188748. [PMID: 29186197 PMCID: PMC5706683 DOI: 10.1371/journal.pone.0188748] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 11/13/2017] [Indexed: 11/19/2022] Open
Abstract
The bioactive, signaling lipid, sphingosine-1-phosphate (S1P), and its analog, fingolimod (FTY720), have previously shown neuroprotective effects against ischemic brain injury. However, the underlying mechanisms have not yet been fully clarified. The roles of autophagy in ischemic stroke are being increasingly recognized. In the present study, we sought to determine whether the S1P pathway is involved in neuronal autophagy and investigate its possible mechanisms following stroke. Interestingly, we found that FTY720 significantly attenuates infarct volumes and reduces neuronal apoptosis on days 1 and 3 post stroke, accompanied by amelioration of functional deficits. Additionally, FTY720 was found to decrease the induction of autophagosome proteins, microtubule-associated protein 1 light chain 3(LC3-II) and Beclin1, following ischemic stroke in a dose-dependent manner. Meanwhile, protein levels of the mammalian target of rapamycin (mTOR) and the 70-kDa ribosomal protein, S6 kinase1 (p70S6K), were also up-regulated in FTY720-treated animals, and the nonspecific SphK inhibitor, N,N-dimethylsphingosine (DMS), was found to cause a reverse effect. Our results indicate that modulation of the S1P signaling pathway by FTY720 could effectively decrease neuronal autophagy through the mTOR/p70S6K pathway and attenuate ischemic brain injury in mice.
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Affiliation(s)
- Xiao Li
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Department of geriatrics, Wuhan General Hospital of PLA, Wuhan, China
| | - Ming-Huan Wang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chuan Qin
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wen-Hui Fan
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Dai-Shi Tian
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jun-Li Liu
- Cancer center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- * E-mail:
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18
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Pierre S, Zhang DD, Suo J, Kern K, Tarighi N, Scholich K. Myc binding protein 2 suppresses M2-like phenotypes in macrophages during zymosan-induced inflammation in mice. Eur J Immunol 2017; 48:239-249. [PMID: 29067676 DOI: 10.1002/eji.201747129] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 09/09/2017] [Accepted: 10/17/2017] [Indexed: 02/03/2023]
Abstract
MYCBP2 is an E3 ubiquitin ligase, which is well characterized as a key element in the inhibition of neuronal growth, synapse formation and synaptic strength by regulating several signaling pathways. Although MYCBP2 was suspected to be expressed also in immune cells, to date nothing is known about its role in inflammation. We used Multi-epitope ligand cartography (MELC), a method for multiple sequential immunohistology, to show that MYCBP2 is strongly expressed in monocyte-derived macrophages during zymosan-induced inflammation. We generated a myeloid-specific knockout mouse and found that loss of MYCBP2 in myeloid cells reduced nociceptive (painful) behavior during the resolution phase (1-3 days after zymosan injection). Quantitative MELC analyses and flow cytometric analysis showed an increased number of CD206-expressing macrophages in the inflamed paw tissue. Fittingly, CD206 and arginase 1 expression was upregulated in MYCBP2-deficient bone marrow-derived macrophages after polarization with IL10 or IL4. The regulation of protein expression in these macrophages by MYCBP2 varied depending on the polarization signal. The increased IL10-induced CD206 expression in MYCBP2-deficient macrophages was mediated by p38 MAPK, while IL4-induced CD206 expression in MYCBP2-deficient macrophages was mediated by protein kinase A.
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Affiliation(s)
- Sandra Pierre
- Institut für Klinische Pharmakologie, Uniklinikum Frankfurt, Germany
| | - Dong Dong Zhang
- Institut für Klinische Pharmakologie, Uniklinikum Frankfurt, Germany
| | - Jing Suo
- Institut für Klinische Pharmakologie, Uniklinikum Frankfurt, Germany
| | - Katharina Kern
- Institut für Klinische Pharmakologie, Uniklinikum Frankfurt, Germany
| | - Neda Tarighi
- Institut für Klinische Pharmakologie, Uniklinikum Frankfurt, Germany
| | - Klaus Scholich
- Institut für Klinische Pharmakologie, Uniklinikum Frankfurt, Germany
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19
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Sharma L, Prakash H. Sphingolipids Are Dual Specific Drug Targets for the Management of Pulmonary Infections: Perspective. Front Immunol 2017; 8:378. [PMID: 28400772 PMCID: PMC5372786 DOI: 10.3389/fimmu.2017.00378] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 03/16/2017] [Indexed: 11/13/2022] Open
Abstract
Sphingolipids are the major constituent of the mucus secreted by the cells of epithelial linings of lungs where they maintain the barrier functions and prevent microbial invasion. Sphingolipids are interconvertible, and their primary and secondary metabolites have both structural and functional roles. Out of several sphingolipid metabolites, sphingosine-1 phosphate (S1P) and ceramide are central molecules and decisive for sphingolipid signaling. These are produced by enzymatic activity of sphingosine kinase-1 (SK-1) upon the challenge with either biological or physiological stresses. S1P and ceramide rheostat are important for the progression of various pathologies, which are manifested by inflammatory cascade. S1P is a well-established secondary messenger and associated with various neuronal, metabolic, and inflammatory diseases other than respiratory infections such as Chlamydia pneumoniae, Streptococcus pneumoniae, and Mycobacterium tuberculosis. These pathogens are known to exploit sphingolipid metabolism for their opportunistic survival. Decreased sphingosine kinase activity/S1P content in the lung and peripheral blood of tuberculosis patients clearly indicated a dysregulation of sphingolipid metabolism during infection and suggest that sphingolipid metabolism is important for management of infection by the host. Our previous study has demonstrated that gain of SK-1 activity is important for the maturation of phagolysosomal compartment, innate activation of macrophages, and subsequent control of mycobacterial replication/growth in macrophages. Furthermore, S1P-mediated amelioration of lung pathology and disease severity in TB patients is believed to be mediated by the selective activation or rearrangement of various S1P receptors (S1PR) particularly S1PR2, which has been effective in controlling respiratory fungal pathogens. Therefore, such specificity of S1P-S1PR would be paramount for triggering inflammatory events, subsequent activation, and fostering bactericidal potential in macrophages for the control of TB. In this review, we have discussed and emphasized that sphingolipids may represent effective novel, yet dual specific drug targets for controlling pulmonary infections.
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Affiliation(s)
- Lalita Sharma
- Laboratory of Translational Medicine, School of Life Sciences, University of Hyderabad , Hyderabad, Telengana , India
| | - Hridayesh Prakash
- Laboratory of Translational Medicine, School of Life Sciences, University of Hyderabad , Hyderabad, Telengana , India
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20
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Snijders AM, Liu Y, Su L, Huang Y, Mao JH. Expression profiling reveals transcriptional regulation by Fbxw7/mTOR pathway in radiation-induced mouse thymic lymphomas. Oncotarget 2016; 6:44794-805. [PMID: 26575021 PMCID: PMC4792592 DOI: 10.18632/oncotarget.6328] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/23/2015] [Indexed: 01/12/2023] Open
Abstract
The tumor suppressor gene FBXW7 is deleted and mutated in many different types of human cancers. FBXW7 primarily exerts its tumor suppressor activity by ubiquitinating different oncoproteins including mTOR. Here we used gene transcript profiling to gain a deeper understanding of the role of FBXW7 in tumor development and to determine the influence of mTOR inhibition by rapamycin on tumor transcriptome and biological functions. In comparison to tumors from p53 single heterozygous (p53+/−) mice, we find that radiation-induced thymic lymphomas from Fbxw7/p53 double heterozygous (Fbxw7+/−p53+/−) mice show significant deregulation of cholesterol metabolic processes independent of rapamycin treatment, while cell cycle related genes were upregulated in tumors from placebo treated Fbxw7+/−p53+/− mice, but not in tumors from rapamycin treated Fbxw7+/−p53+/− mice. On the other hand, tumors from rapamycin treated Fbxw7+/−p53+/− mice were enriched for genes involved in the integrated stress response, an adaptive mechanism to survive in stressful environments. Finally, we demonstrated that the Fbxw7 gene signatures identified in mouse tumors significantly overlap with FBXW7 co-expressed genes in human cancers. Importantly these common FBXW7 gene signatures between mouse and human are predictive for disease-free survival in human colon, breast and lung adenocarcinoma cancer patients. These results provide novel insights into the role of FBXW7 in tumor development and have identified a number of potential targets for therapeutic intervention.
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Affiliation(s)
- Antoine M Snijders
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Yueyong Liu
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.,Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Li Su
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Yurong Huang
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jian-Hua Mao
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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21
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Grill B, Murphey RK, Borgen MA. The PHR proteins: intracellular signaling hubs in neuronal development and axon degeneration. Neural Dev 2016; 11:8. [PMID: 27008623 PMCID: PMC4806438 DOI: 10.1186/s13064-016-0063-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/15/2016] [Indexed: 11/10/2022] Open
Abstract
During development, a coordinated and integrated series of events must be accomplished in order to generate functional neural circuits. Axons must navigate toward target cells, build synaptic connections, and terminate outgrowth. The PHR proteins (consisting of mammalian Phr1/MYCBP2, Drosophila Highwire and C. elegans RPM-1) function in each of these events in development. Here, we review PHR function across species, as well as the myriad of signaling pathways PHR proteins regulate. These findings collectively suggest that the PHR proteins are intracellular signaling hubs, a concept we explore in depth. Consistent with prominent developmental functions, genetic links have begun to emerge between PHR signaling networks and neurodevelopmental disorders, such as autism, schizophrenia and intellectual disability. Finally, we discuss the recent and important finding that PHR proteins regulate axon degeneration, which has further heightened interest in this fascinating group of molecules.
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Affiliation(s)
- Brock Grill
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, FL, 33458, USA.
| | - Rodney K Murphey
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, 33458, USA
| | - Melissa A Borgen
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, FL, 33458, USA
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22
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Abstract
Maintenance of cellular homeostasis requires tight and coordinated control of numerous metabolic pathways, which are governed by interconnected networks of signaling pathways and energy-sensing regulators. Autophagy, a lysosomal degradation pathway by which the cell self-digests its own components, has over the past decade been recognized as an essential part of metabolism. Autophagy not only rids the cell of excessive or damaged organelles, misfolded proteins, and invading microorganisms, it also provides nutrients to maintain crucial cellular functions. Besides serving as essential structural moieties of biomembranes, lipids including sphingolipids are increasingly being recognized as central regulators of a number of important cellular processes, including autophagy. In the present review we describe how sphingolipids, with special emphasis on ceramides and sphingosine-1-phosphate, can act as physiological regulators of autophagy in relation to cellular and organismal growth, survival, and aging.
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Affiliation(s)
- Eva Bang Harvald
- Villum Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
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Dörr A, Pierre S, Zhang DD, Henke M, Holland S, Scholich K. MYCBP2 Is a Guanosine Exchange Factor for Ran Protein and Determines Its Localization in Neurons of Dorsal Root Ganglia. J Biol Chem 2015; 290:25620-35. [PMID: 26304119 DOI: 10.1074/jbc.m115.646901] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Indexed: 11/06/2022] Open
Abstract
The small GTPase Ran coordinates retrograde axonal transport in neurons, spindle assembly during mitosis, and the nucleo-cytoplasmic transport of mRNA. Its localization is tightly regulated by the GTPase-activating protein RanGAP1 and the nuclear guanosine exchange factor (GEF) RCC1. We show that loss of the neuronal E3 ubiquitin ligase MYCBP2 caused the up-regulation of Ran and RanGAP1 in dorsal root ganglia (DRG) under basal conditions and during inflammatory hyperalgesia. SUMOylated RanGAP1 physically interacted with MYCBP2 and inhibited its E3 ubiquitin ligase activity. Stimulation of neurons induced a RanGAP1-dependent translocation of MYCBP2 to the nucleus. In the nucleus of DRG neurons MYCBP2 co-localized with Ran and facilitated through its RCC1-like domain the GDP/GTP exchange of Ran. In accordance with the necessity of a GEF to promote GTP-binding and nuclear export of Ran, the nuclear localization of Ran was strongly increased in MYCBP2-deficient DRGs. The finding that other GEFs for Ran besides RCC1 exist gives new insights in the complexity of the regulation of the Ran signaling pathway.
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Affiliation(s)
- Angela Dörr
- From the Institut für Klinische Pharmakologie, Pharmazentrum Frankfurt, Klinikum der Goethe-Universität Frankfurt, Frankfurt 60590, Germany
| | - Sandra Pierre
- From the Institut für Klinische Pharmakologie, Pharmazentrum Frankfurt, Klinikum der Goethe-Universität Frankfurt, Frankfurt 60590, Germany
| | - Dong D Zhang
- From the Institut für Klinische Pharmakologie, Pharmazentrum Frankfurt, Klinikum der Goethe-Universität Frankfurt, Frankfurt 60590, Germany
| | - Marina Henke
- From the Institut für Klinische Pharmakologie, Pharmazentrum Frankfurt, Klinikum der Goethe-Universität Frankfurt, Frankfurt 60590, Germany
| | - Sabrina Holland
- From the Institut für Klinische Pharmakologie, Pharmazentrum Frankfurt, Klinikum der Goethe-Universität Frankfurt, Frankfurt 60590, Germany
| | - Klaus Scholich
- From the Institut für Klinische Pharmakologie, Pharmazentrum Frankfurt, Klinikum der Goethe-Universität Frankfurt, Frankfurt 60590, Germany
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24
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Dibble CC, Cantley LC. Regulation of mTORC1 by PI3K signaling. Trends Cell Biol 2015; 25:545-55. [PMID: 26159692 DOI: 10.1016/j.tcb.2015.06.002] [Citation(s) in RCA: 552] [Impact Index Per Article: 61.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 06/08/2015] [Accepted: 06/08/2015] [Indexed: 11/29/2022]
Abstract
The class I phosphoinositide 3-kinase (PI3K)-mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) signaling network directs cellular metabolism and growth. Activation of mTORC1 [composed of mTOR, regulatory-associated protein of mTOR (Raptor), mammalian lethal with SEC13 protein 8(mLST8), 40-kDa proline-rich Akt substrate (PRAS40), and DEP domain-containing mTOR-interacting protein (DEPTOR)] depends on the Ras-related GTPases (Rags) and Ras homolog enriched in brain (Rheb) GTPase and requires signals from amino acids, glucose, oxygen, energy (ATP), and growth factors (including cytokines and hormones such as insulin). Here we discuss the signal transduction mechanisms through which growth factor-responsive PI3K signaling activates mTORC1. We focus on how PI3K-dependent activation of Akt and spatial regulation of the tuberous sclerosis complex (TSC) complex (TSC complex) [composed of TSC1, TSC2, and Tre2-Bub2-Cdc16-1 domain family member 7 (TBC1D7)] switches on Rheb at the lysosome, where mTORC1 is activated. Integration of PI3K- and amino acid-dependent signals upstream of mTORC1 at the lysosome is detailed in a working model. A coherent understanding of the PI3K-mTORC1 network is imperative as its dysregulation has been implicated in diverse pathologies including cancer, diabetes, autism, and aging.
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Affiliation(s)
- Christian C Dibble
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Lewis C Cantley
- Meyer Cancer Center, Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA.
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25
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Kleiman E, Salyakina D, De Heusch M, Hoek KL, Llanes JM, Castro I, Wright JA, Clark ES, Dykxhoorn DM, Capobianco E, Takeda A, Renauld JC, Khan WN. Distinct Transcriptomic Features are Associated with Transitional and Mature B-Cell Populations in the Mouse Spleen. Front Immunol 2015; 6:30. [PMID: 25717326 PMCID: PMC4324157 DOI: 10.3389/fimmu.2015.00030] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 01/15/2015] [Indexed: 11/30/2022] Open
Abstract
Splenic transitional B-cells (T1 and T2) are selected to avoid self-reactivity and to safeguard against autoimmunity, then differentiate into mature follicular (FO-I and FO-II) and marginal zone (MZ) subsets. Transcriptomic analysis by RNA-seq of the five B-cell subsets revealed T1 cell signature genes included RAG suggesting a potential for receptor revision. T1 to T2 B-cell differentiation was marked by a switch from Myb to Myc, increased expression of the PI3K adapter DAP10 and MHC class II. FO-II may be an intermediate in FO-I differentiation and may also become MZ B-cells as suggested by principle component analysis. MZ B-cells possessed the most distinct transcriptome including down-regulation of CD45 phosphatase-associated protein (CD45-AP/PTPRC-AP), as well as upregulation of IL-9R and innate molecules TLR3, TLR7, and bactericidal Perforin-2 (MPEG1). Among the endosomal TLRs, stimulation via TLR3 further enhanced Perforin-2 expression exclusively in MZ B-cells. Using gene-deleted and overexpressing transgenic mice we show that IL-9/IL-9R interaction resulted in rapid activation of STAT1, 3, and 5, primarily in MZ B-cells. Importantly, CD45-AP mutant mice had reduced transitional and increased mature MZ and FO B-cells, suggesting that it prevents premature entry of transitional B-cells to the mature B-cell pool or their survival and proliferation. Together, these findings suggest, developmental plasticity among splenic B-cell subsets, potential for receptor revision in peripheral tolerance whereas enhanced metabolism coincides with T2 to mature B-cell differentiation. Further, unique core transcriptional signatures in MZ B-cells may control their innate features.
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Affiliation(s)
- Eden Kleiman
- Department of Microbiology and Immunology, Miller School of Medicine, University of Miami , Miami, FL , USA
| | - Daria Salyakina
- Center for Computational Science, University of Miami , Miami, FL , USA
| | - Magali De Heusch
- Ludwig Institute for Cancer Research, Brussels Branch , Brussels , Belgium ; de Duve Institute, Université Catholique de Louvain , Brussels , Belgium
| | - Kristen L Hoek
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine , Nashville, TN , USA
| | - Joan M Llanes
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine , Nashville, TN , USA
| | - Iris Castro
- Department of Microbiology and Immunology, Miller School of Medicine, University of Miami , Miami, FL , USA
| | - Jacqueline A Wright
- Department of Microbiology and Immunology, Miller School of Medicine, University of Miami , Miami, FL , USA
| | - Emily S Clark
- Department of Microbiology and Immunology, Miller School of Medicine, University of Miami , Miami, FL , USA
| | - Derek M Dykxhoorn
- Hussman Institute for Human Genomics, University of Miami , Miami, FL , USA
| | - Enrico Capobianco
- Center for Computational Science, University of Miami , Miami, FL , USA
| | - Akiko Takeda
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis , St. Louis, MO , USA
| | - Jean-Christophe Renauld
- Ludwig Institute for Cancer Research, Brussels Branch , Brussels , Belgium ; de Duve Institute, Université Catholique de Louvain , Brussels , Belgium
| | - Wasif N Khan
- Department of Microbiology and Immunology, Miller School of Medicine, University of Miami , Miami, FL , USA
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26
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Zheng X, Liang Y, He Q, Yao R, Bao W, Bao L, Wang Y, Wang Z. Current models of mammalian target of rapamycin complex 1 (mTORC1) activation by growth factors and amino acids. Int J Mol Sci 2014; 15:20753-69. [PMID: 25402640 PMCID: PMC4264194 DOI: 10.3390/ijms151120753] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 09/24/2014] [Accepted: 10/29/2014] [Indexed: 01/09/2023] Open
Abstract
Mammalian target of rapamycin (mTOR), which is now referred to as mechanistic target of rapamycin, integrates many signals, including those from growth factors, energy status, stress, and amino acids, to regulate cell growth and proliferation, protein synthesis, protein degradation, and other physiological and biochemical processes. The mTOR-Rheb-TSC-TBC complex co-localizes to the lysosome and the phosphorylation of TSC-TBC effects the dissociation of the complex from the lysosome and activates Rheb. GTP-bound Rheb potentiates the catalytic activity of mTORC1. Under conditions with growth factors and amino acids, v-ATPase, Ragulator, Rag GTPase, Rheb, hVps34, PLD1, and PA have important but disparate effects on mTORC1 activation. In this review, we introduce five models of mTORC1 activation by growth factors and amino acids to provide a comprehensive theoretical foundation for future research.
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Affiliation(s)
- Xu Zheng
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Yan Liang
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Qiburi He
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Ruiyuan Yao
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Wenlei Bao
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Lili Bao
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Yanfeng Wang
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
| | - Zhigang Wang
- College of Life Sciences, Inner Mongolia University, Hohhot 010021, China.
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27
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Holland S, Scholich K. Regulation of neuronal functions by the E3-ubiquitinligase Protein Associated with MYC (MYCBP2). Commun Integr Biol 2014. [DOI: 10.4161/cib.15967] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Mazhab-Jafari MT, Marshall CB, Ho J, Ishiyama N, Stambolic V, Ikura M. Structure-guided mutation of the conserved G3-box glycine in Rheb generates a constitutively activated regulator of mammalian target of rapamycin (mTOR). J Biol Chem 2014; 289:12195-201. [PMID: 24648513 DOI: 10.1074/jbc.c113.543736] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Constitutively activated variants of small GTPases, which provide valuable functional probes of their role in cellular signaling pathways, can often be generated by mutating the canonical catalytic residue (e.g. Ras Q61L) to impair GTP hydrolysis. However, this general approach is ineffective for a substantial fraction of the small GTPase family in which this residue is not conserved (e.g. Rap) or not catalytic (e.g. Rheb). Using a novel engineering approach, we have manipulated nucleotide binding through structure-guided substitutions of an ultraconserved glycine residue in the G3-box motif (DXXG). Substitution of Rheb Gly-63 with alanine impaired both intrinsic and TSC2 GTPase-activating protein (GAP)-mediated GTP hydrolysis by displacing the hydrolytic water molecule, whereas introduction of a bulkier valine side chain selectively blocked GTP binding by steric occlusion of the γ-phosphate. Rheb G63A stimulated phosphorylation of the mTORC1 substrate p70S6 kinase more strongly than wild-type, thus offering a new tool for mammalian target of rapamycin (mTOR) signaling.
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Affiliation(s)
- Mohammad T Mazhab-Jafari
- From the Campbell Family Cancer Research Institute, Princess Margaret Cancer Centre and, Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada
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29
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Fernández AI, Barragán C, Fernández A, Rodríguez MC, Villanueva B. Copy number variants in a highly inbred Iberian porcine strain. Anim Genet 2014; 45:357-66. [PMID: 24597621 DOI: 10.1111/age.12137] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/17/2014] [Indexed: 01/06/2023]
Abstract
We carried out a comprehensive genomic analysis of porcine copy number variants (CNVs) based on whole-genome SNP genotyping data and provided new measures of genomic diversity (number, length and distribution of CNV events) for a highly inbred strain (the Guadyerbas strain). This strain represents one of the most ancient surviving populations of the Iberian breed, and it is currently in serious danger of extinction. CNV detection was conducted on the complete Guadyerbas population, adjusted for genomic waves, and used strict quality criteria, pedigree information and the latest porcine genome annotation. The analysis led to the detection of 65 CNV regions (CNVRs). These regions cover 0.33% of the autosomal genome of this particular strain. Twenty-nine of these CNVRs were identified here for the first time. The relatively low number of detected CNVRs is in line with the low variability and high inbreeding estimated previously for this Iberian strain using pedigree, microsatellite or SNP data. A comparison across different porcine studies has revealed that more than half of these regions overlap with previously identified CNVRs or multicopy regions. Also, a preliminary analysis of CNV detection using whole-genome sequence data for four Guadyerbas pigs showed overlapping for 16 of the CNVRs, supporting their reliability. Some of the identified CNVRs contain relevant functional genes (e.g., the SCD and USP15 genes), which are worth being further investigated because of their importance in determining the quality of Iberian pig products. The CNVR data generated could be useful for improving the porcine genome annotation.
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Affiliation(s)
- A I Fernández
- Departamento de Mejora Genética Animal, INIA, Ctra. De la Coruña km. 7.5, Madrid, 28040, Spain
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30
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Taniguchi M, Kitatani K, Kondo T, Hashimoto-Nishimura M, Asano S, Hayashi A, Mitsutake S, Igarashi Y, Umehara H, Takeya H, Kigawa J, Okazaki T. Regulation of autophagy and its associated cell death by "sphingolipid rheostat": reciprocal role of ceramide and sphingosine 1-phosphate in the mammalian target of rapamycin pathway. J Biol Chem 2012; 287:39898-910. [PMID: 23035115 DOI: 10.1074/jbc.m112.416552] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The role of "sphingolipid rheostat" by ceramide and sphingosine 1-phosphate (S1P) in the regulation of autophagy remains unclear. In human leukemia HL-60 cells, amino acid deprivation (AA(-)) caused autophagy with an increase in acid sphingomyleinase (SMase) activity and ceramide, which serves as an autophagy inducing lipid. Knockdown of acid SMase significantly suppressed the autophagy induction. S1P treatment counteracted autophagy induction by AA(-) or C(2)-ceramide. AA(-) treatment promoted mammalian target of rapamycin (mTOR) dephosphorylation/inactivation, inducing autophagy. S1P treatment suppressed mTOR inactivation and autophagy induction by AA(-). S1P exerts biological actions via cell surface receptors, and S1P(3) among five S1P receptors was predominantly expressed in HL-60 cells. We evaluated the involvement of S1P(3) in suppressing autophagy induction. S1P treatment of CHO cells had no effects on mTOR inactivation and autophagy induction by AA(-) or C(2)-ceramide. Whereas S1P treatment of S1P(3) overexpressing CHO cells resulted in activation of the mTOR pathway, preventing cells from undergoing autophagy induced by AA(-) or C(2)-ceramide. These results indicate that S1P-S1P(3) plays a role in counteracting ceramide signals that mediate mTOR-controlled autophagy. In addition, we evaluated the involvement of ceramide-activated protein phosphatases (CAPPs) in ceramide-dependent inactivation of the mTOR pathway. Inhibition of CAPP by okadaic acid in AA(-)- or C(2)-ceramide-treated cells suppressed dephosphorylation/inactivation of mTOR, autophagy induction, and autophagy-associated cell death, indicating a novel role of ceramide-CAPPs in autophagy induction. Moreover, S1P(3) engagement by S1P counteracted cell death. Taken together, these results indicated that sphingolipid rheostat in ceramide-CAPPs and S1P-S1P(3) signaling modulates autophagy and its associated cell death through regulation of the mTOR pathway.
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Affiliation(s)
- Makoto Taniguchi
- Division of Clinical Laboratory Medicine, Faculty of Medicine, Tottori University, 86 Nishi-Machi, Yonago 683-8503, Japan
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Han S, Kim S, Bahl S, Li L, Burande CF, Smith N, James M, Beauchamp RL, Bhide P, DiAntonio A, Ramesh V. The E3 ubiquitin ligase protein associated with Myc (Pam) regulates mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling in vivo through N- and C-terminal domains. J Biol Chem 2012; 287:30063-72. [PMID: 22798074 DOI: 10.1074/jbc.m112.353987] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pam and its homologs (the PHR protein family) are large E3 ubiquitin ligases that function to regulate synapse formation and growth in mammals, zebrafish, Drosophila, and Caenorhabditis elegans. Phr1-deficient mouse models (Phr1(Δ8,9) and Phr1(Magellan), with deletions in the N-terminal putative guanine exchange factor region and the C-terminal ubiquitin ligase region, respectively) exhibit axon guidance/outgrowth defects and striking defects of major axon tracts in the CNS. Our earlier studies identified Pam to be associated with tuberous sclerosis complex (TSC) proteins, ubiquitinating TSC2 and regulating mammalian/mechanistic target of rapamycin (mTOR) signaling. Here, we examine the potential involvement of the TSC/mTOR complex 1(mTORC1) signaling pathway in Phr1-deficient mouse models. We observed attenuation of mTORC1 signaling in the brains of both Phr1(Δ8,9) and Phr1(Magellan) mouse models. Our results establish that Pam regulates TSC/mTOR signaling in vitro and in vivo through two distinct domains. To further address whether Pam regulates mTORC1 through two functionally independent domains, we undertook heterozygous mutant crossing between Phr1(Δ8,9) and Phr1(Magellan) mice to generate a compound heterozygous model to determine whether these two domains can complement each other. mTORC1 signaling was not attenuated in the brains of double mutants (Phr1(Δ8,9/Mag)), confirming that Pam displays dual regulation of the mTORC1 pathway through two functional domains. Our results also suggest that although dysregulation of mTORC1 signaling may be responsible for the corpus callosum defects, other neurodevelopmental defects observed with Phr1 deficiency are independent of mTORC1 signaling. The ubiquitin ligase complex containing Pam-Fbxo45 likely targets additional synaptic and axonal proteins, which may explain the overlapping neurodevelopmental defects observed in Phr1 and Fbxo45 deficiency.
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Affiliation(s)
- Sangyeul Han
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA 02114, USA
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Abstract
Sphingosine-1-phosphate (S1P) was first described as a signaling molecule over 20 years ago. Since then, great strides have been made to reveal its vital roles in vastly different cellular and disease processes. Initially, S1P was considered nothing more than the terminal point of sphingolipid metabolism; however, over the past two decades, a large number of reports have helped unveil its full potential as an important regulatory, bioactive sphingolipid metabolite. S1P has a plethora of physiological functions, due in part to its many sites of actions and its different pools, which are both intra- and extracellular. S1P plays pivotal roles in many physiological processes, including the regulation of cell growth, migration, autophagy, angiogenesis, and survival, and thus, not surprisingly, S1P has been linked to cancer. In this review, we will summarize the vast body of knowledge, highlighting the connection between S1P and cancer. We will also suggest new avenues for future research.
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Holland S, Scholich K. Regulation of neuronal functions by the E3-ubiquitinligase protein associated with MYC (MYCBP2). Commun Integr Biol 2011; 4:513-5. [PMID: 22046451 DOI: 10.4161/cib.4.5.15967] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 04/22/2011] [Indexed: 11/19/2022] Open
Abstract
The E3-ubiquitinligase MYCBP2 regulates neuronal growth, synaptogenesis and synaptic plasticity by modulating several signaling pathways including the p38 MAPK signaling cascade. We found that loss of MYCBP2 in peripheral sensory neurons inhibits the internalization of transient receptor potential vanilloid receptor 1 (TRPV1) in a p38 MAPK-dependent manner. This prevented desensitization of activity-induced calcium increases and prolongs formalin-induced thermal hyperalgesia in mice. Besides its function in pain perception TRPV1 is also involved in the regulation of neuronal growth. Therefore, the observed effect of MYCBP2 on TRPV1 internalization could be part of the mechanisms underlying its well documented regulatory role in neuronal growth. The clarification of the mechanism is important for the understanding of the different MYCBP2-functions in diverse neuronal subpopulations and species.
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Affiliation(s)
- Sabrina Holland
- Pharmazentrum frankfurt/ZAFES; Institute of Clinical Pharmacology; Klinikum der Goethe-Universität Frankfurt, Germany
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34
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Holland S, Coste O, Zhang DD, Pierre SC, Geisslinger G, Scholich K. The ubiquitin ligase MYCBP2 regulates transient receptor potential vanilloid receptor 1 (TRPV1) internalization through inhibition of p38 MAPK signaling. J Biol Chem 2010; 286:3671-80. [PMID: 21098484 DOI: 10.1074/jbc.m110.154765] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The E3 ubiquitin ligase MYCBP2 negatively regulates neuronal growth, synaptogenesis, and synaptic strength. More recently it was shown that MYCBP2 is also involved in receptor and ion channel internalization. We found that mice with a MYCBP2-deficiency in peripheral sensory neurons show prolonged thermal hyperalgesia. Loss of MYCBP2 constitutively activated p38 MAPK and increased expression of several proteins involved in receptor trafficking. Surprisingly, loss of MYCBP2 inhibited internalization of transient receptor potential vanilloid receptor 1 (TRPV1) and prevented desensitization of capsaicin-induced calcium increases. Lack of desensitization, TRPV internalization and prolonged hyperalgesia were reversed by inhibition of p38 MAPK. The effects were TRPV-specific, since neither mustard oil-induced desensitization nor behavioral responses to mechanical stimuli were affected. In summary, we show here for the first time that p38 MAPK activation can inhibit activity-induced ion channel internalization and that MYCBP2 regulates internalization of TRPV1 in peripheral sensory neurons as well as duration of thermal hyperalgesia through p38 MAPK.
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Affiliation(s)
- Sabrina Holland
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/ZAFES, Klinikum der Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
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Drummond MJ, Dreyer HC, Fry CS, Glynn EL, Rasmussen BB. Nutritional and contractile regulation of human skeletal muscle protein synthesis and mTORC1 signaling. J Appl Physiol (1985) 2009; 106:1374-84. [PMID: 19150856 DOI: 10.1152/japplphysiol.91397.2008] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In this review we discuss current findings in the human skeletal muscle literature describing the acute influence of nutrients (leucine-enriched essential amino acids in particular) and resistance exercise on muscle protein synthesis and mammalian target of rapamycin complex 1 (mTORC1) signaling. We show that essential amino acids and an acute bout of resistance exercise independently stimulate human skeletal muscle protein synthesis. It also appears that ingestion of essential amino acids following resistance exercise leads to an even larger increase in the rate of muscle protein synthesis compared with the independent effects of nutrients or muscle contraction. Until recently the cellular mechanisms responsible for controlling the rate of muscle protein synthesis in humans were unknown. In this review, we highlight new studies in humans that have clearly shown the mTORC1 signaling pathway is playing an important regulatory role in controlling muscle protein synthesis in response to nutrients and/or muscle contraction. We propose that essential amino acid ingestion shortly following a bout of resistance exercise is beneficial in promoting skeletal muscle growth and may be useful in counteracting muscle wasting in a variety of conditions such as aging, cancer cachexia, physical inactivity, and perhaps during rehabilitation following trauma or surgery.
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Affiliation(s)
- Micah J Drummond
- Department of Physical Therapy, University of Texas Medical Branch, , Galveston, TX 77555-1144, USA
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