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Fulbert M, El Amrani M, Baillet C, Lecolle K, Ernst O, Louvet A, Pruvot FR, Huglo D, Truant S. Sarcopenia does not affect liver regeneration and postoperative course after a major hepatectomy. A prospective study on 125 patients using CT volumetry and HIDA scintigraphy. Clin Res Hepatol Gastroenterol 2024; 48:102332. [PMID: 38574887 DOI: 10.1016/j.clinre.2024.102332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 03/28/2024] [Accepted: 04/01/2024] [Indexed: 04/06/2024]
Abstract
BACKGROUND & OBJECTIVES Sarcopenia is a morbi-mortality risk factor in digestive surgery, though its impact after major hepatectomy (MH) remains unknown. This prospective pilot study investigated whether volume and function of a regenerating liver is influenced by body composition. METHODS From 2011 to 2016, 125 consecutive patients had computed tomography and 99mTc-labelled-mebrofenin SPECT-scintigraphy before and after MH at day 7 and 1 month for measurements of liver volumes and functions. L3 vertebra muscle mass identified sarcopenia. Primary endpoint was the impact of sarcopenia on regeneration capacities (i.e. volume/function changes and post-hepatectomy liver failure (PHLF) rate). Secondary endpoint was 3-month morbi-mortality. RESULTS Sarcopenic patients (SP; N = 69) were significantly older than non-sarcopenic (NSP), with lower BMI and more malignancies, but with comparable liver function/volume at baseline. Postoperatively, SP showed higher rates of ISGLS_PHLF (24.6 % vs 10.9 %; p = 0.05) but with comparable rates of severe morbidity (23.2 % vs 16.4 %; p = 0.35), overall (8.7 % vs 3.6 %; p = 0.3) and PHLF-related mortality (8,7 % vs 1.8 %; p = 0.075). After matching on the extent of resection or using propensity score, regeneration and PHLF rates were similar. CONCLUSION This prospective study using first sequential SPECT-scintigraphy showed that sarcopenia by itself does not affect liver regeneration capacities and short-term postoperative course after MH.
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Affiliation(s)
- Maxence Fulbert
- Department of Digestive Surgery and Transplantation, CHU Lille, University Lille, Lille F-59000, France
| | - Mehdi El Amrani
- Department of Digestive Surgery and Transplantation, CHU Lille, University Lille, Lille F-59000, France; CANTHER laboratory "Cancer Heterogeneity, Plasticity and Resistance to Therapies" UMR-S1277, Team "Mucins, Cancer and Drug Resistance", Lille F-59000, France
| | - Clio Baillet
- Department of Nuclear Medicine, CHU Lille, University Lille, Lille F-59000, France
| | - Katia Lecolle
- Department of Digestive Surgery and Transplantation, CHU Lille, University Lille, Lille F-59000, France
| | - Olivier Ernst
- Department of Digestive Radiology, CHU Lille, University Lille, Lille F-59000, France
| | - Alexandre Louvet
- Department of Hepatogastroenterology, CHU Lille, University Lille, Lille F-59000, France
| | - François-René Pruvot
- Department of Digestive Surgery and Transplantation, CHU Lille, University Lille, Lille F-59000, France
| | - Damien Huglo
- Department of Nuclear Medicine, CHU Lille, University Lille, Lille F-59000, France
| | - Stéphanie Truant
- Department of Digestive Surgery and Transplantation, CHU Lille, University Lille, Lille F-59000, France; CANTHER laboratory "Cancer Heterogeneity, Plasticity and Resistance to Therapies" UMR-S1277, Team "Mucins, Cancer and Drug Resistance", Lille F-59000, France.
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2
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Zhou X, Ohgaki R, Jin C, Xu M, Okanishi H, Endou H, Kanai Y. Inhibition of amino acid transporter LAT1 in cancer cells suppresses G0/G1-S transition by downregulating cyclin D1 via p38 MAPK activation. J Pharmacol Sci 2024; 154:182-191. [PMID: 38395519 DOI: 10.1016/j.jphs.2024.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/16/2024] [Accepted: 01/22/2024] [Indexed: 02/25/2024] Open
Abstract
L-type amino acid transporter 1 (LAT1, SLC7A5) is upregulated in various cancers and associated with disease progression. Nanvuranlat (Nanv; JPH203, KYT-0353), a selective LAT1 inhibitor, suppresses the uptake of large neutral amino acids required for rapid growth and proliferation of cancer cells. Previous studies have suggested that the inhibition of LAT1 by Nanv induces the cell cycle arrest at G0/G1 phase, although the underlying mechanisms remain unclear. Using pancreatic cancer cells arrested at the restriction check point (R) by serum deprivation, we found that the Nanv drastically suppresses the G0/G1-S transition after release. This blockade of the cell cycle progression was accompanied by a sustained activation of p38 mitogen-activated protein kinase (MAPK) and subsequent phosphorylation-dependent proteasomal degradation of cyclin D1. Isoform-specific knockdown of p38 MAPK revealed the predominant contribution of p38α. Proteasome inhibitors restored the cyclin D1 amount and released the cell cycle arrest caused by Nanv. The increased phosphorylation of p38 MAPK and the decrease of cyclin D1 were recapitulated in xenograft tumor models treated with Nanv. This study contributes to delineating the pharmacological activities of LAT1 inhibitors as anti-cancer agents and provides significant insights into the molecular basis of the amino acid-dependent cell cycle checkpoint at G0/G1 phase.
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Affiliation(s)
- Xinyu Zhou
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Ryuichi Ohgaki
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan; Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita, Osaka, 565-0871, Japan.
| | - Chunhuan Jin
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Minhui Xu
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hiroki Okanishi
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hitoshi Endou
- J-Pharma Co., Ltd., Yokohama, Kanagawa, 230-0046, Japan
| | - Yoshikatsu Kanai
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan; Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita, Osaka, 565-0871, Japan.
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Wu H, Kren BT, Lane AN, Cassel TA, Higashi RM, Fan TWM, Scaria GS, Shekels LL, Klein MA, Albrecht JH. Cyclin D1 extensively reprograms metabolism to support biosynthetic pathways in hepatocytes. J Biol Chem 2023; 299:105407. [PMID: 38152849 PMCID: PMC10687208 DOI: 10.1016/j.jbc.2023.105407] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 10/15/2023] [Accepted: 10/17/2023] [Indexed: 12/29/2023] Open
Abstract
Cell proliferation requires metabolic reprogramming to accommodate biosynthesis of new cell components, and similar alterations occur in cancer cells. However, the mechanisms linking the cell cycle machinery to metabolism are not well defined. Cyclin D1, along with its main partner cyclin-dependent kinase 4 (Cdk4), is a pivotal cell cycle regulator and driver oncogene that is overexpressed in many cancers. Here, we examine hepatocyte proliferation to define novel effects of cyclin D1 on biosynthetic metabolism. Metabolomic studies reveal that cyclin D1 broadly promotes biosynthetic pathways including glycolysis, the pentose phosphate pathway, and the purine and pyrimidine nucleotide synthesis in hepatocytes. Proteomic analyses demonstrate that overexpressed cyclin D1 binds to numerous metabolic enzymes including those involved in glycolysis and pyrimidine synthesis. In the glycolysis pathway, cyclin D1 activates aldolase and GAPDH, and these proteins are phosphorylated by cyclin D1/Cdk4 in vitro. De novo pyrimidine synthesis is particularly dependent on cyclin D1. Cyclin D1/Cdk4 phosphorylates the initial enzyme of this pathway, carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase (CAD), and metabolomic analysis indicates that cyclin D1 depletion markedly reduces the activity of this enzyme. Pharmacologic inhibition of Cdk4 along with the downstream pyrimidine synthesis enzyme dihydroorotate dehydrogenase synergistically inhibits proliferation and survival of hepatocellular carcinoma cells. These studies demonstrate that cyclin D1 promotes a broad network of biosynthetic pathways in hepatocytes, and this model may provide insights into potential metabolic vulnerabilities in cancer cells.
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Affiliation(s)
- Heng Wu
- Division of Gastroenterology, Hepatology, and Nutrition, University of Minnesota, Minneapolis, Minnesota, USA
| | - Betsy T Kren
- Research Service, Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
| | - Andrew N Lane
- Center for Environmental and Systems Biochemistry, Department of Toxicology and Cancer Biology, and Markey Cancer Center, University of Kentucky, Lexington, Kentucky, USA
| | - Teresa A Cassel
- Center for Environmental and Systems Biochemistry, Department of Toxicology and Cancer Biology, and Markey Cancer Center, University of Kentucky, Lexington, Kentucky, USA
| | - Richard M Higashi
- Center for Environmental and Systems Biochemistry, Department of Toxicology and Cancer Biology, and Markey Cancer Center, University of Kentucky, Lexington, Kentucky, USA
| | - Teresa W M Fan
- Center for Environmental and Systems Biochemistry, Department of Toxicology and Cancer Biology, and Markey Cancer Center, University of Kentucky, Lexington, Kentucky, USA
| | - George S Scaria
- Hematology and Oncology Division, Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
| | - Laurie L Shekels
- Research Service, Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
| | - Mark A Klein
- Hematology and Oncology Division, Minneapolis VA Health Care System, Minneapolis, Minnesota, USA
| | - Jeffrey H Albrecht
- Division of Gastroenterology, Hepatology, and Nutrition, University of Minnesota, Minneapolis, Minnesota, USA.
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4
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Yu Z, Yang Z, Ren G, Wang Y, Luo X, Zhu F, Yu S, Jia L, Chen M, Worley PF, Xiao B. GATOR2 complex-mediated amino acid signaling regulates brain myelination. Proc Natl Acad Sci U S A 2022; 119:e2110917119. [PMID: 35022234 PMCID: PMC8784133 DOI: 10.1073/pnas.2110917119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 11/16/2021] [Indexed: 02/05/2023] Open
Abstract
Amino acids are essential for cell growth and metabolism. Amino acid and growth factor signaling pathways coordinately regulate the mechanistic target of rapamycin complex 1 (mTORC1) kinase in cell growth and organ development. While major components of amino acid signaling mechanisms have been identified, their biological functions in organ development are unclear. We aimed to understand the functions of the critically positioned amino acid signaling complex GAP activity towards Rags 2 (GATOR2) in brain development. GATOR2 mediates amino acid signaling to mTORC1 by directly linking the amino acid sensors for arginine and leucine to downstream signaling complexes. Now, we report a role of GATOR2 in oligodendrocyte myelination in postnatal brain development. We show that the disruption of GATOR2 complex by genetic deletion of meiosis regulator for oocyte development (Mios, encoding a component of GATOR2) selectively impairs the formation of myelinating oligodendrocytes, thus brain myelination, without apparent effects on the formation of neurons and astrocytes. The loss of Mios impairs cell cycle progression of oligodendrocyte precursor cells, leading to their reduced proliferation and differentiation. Mios deletion manifests a cell type-dependent effect on mTORC1 in the brain, with oligodendroglial mTORC1 selectively affected. However, the role of Mios/GATOR2 in oligodendrocyte formation and myelination involves mTORC1-independent function. This study suggests that GATOR2 coordinates amino acid and growth factor signaling to regulate oligodendrocyte myelination.
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Affiliation(s)
- Zongyan Yu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin 150000, People's Republic of China
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518005, People's Republic of China
- Department of Biology, School of Life Sciences, Brain Research Center, Southern University of Science and Technology, Shenzhen 518000, People's Republic of China
| | - Zhiwen Yang
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518005, People's Republic of China
- Department of Biology, School of Life Sciences, Brain Research Center, Southern University of Science and Technology, Shenzhen 518000, People's Republic of China
| | - Guoru Ren
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518005, People's Republic of China
- Department of Biology, School of Life Sciences, Brain Research Center, Southern University of Science and Technology, Shenzhen 518000, People's Republic of China
| | - Yingjie Wang
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518005, People's Republic of China
- Department of Biology, School of Life Sciences, Brain Research Center, Southern University of Science and Technology, Shenzhen 518000, People's Republic of China
| | - Xiang Luo
- School of Life Science and Technology, Harbin Institute of Technology, Harbin 150000, People's Republic of China
- Department of Biology, School of Life Sciences, Brain Research Center, Southern University of Science and Technology, Shenzhen 518000, People's Republic of China
| | - Feiyan Zhu
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518005, People's Republic of China
- Department of Biology, School of Life Sciences, Brain Research Center, Southern University of Science and Technology, Shenzhen 518000, People's Republic of China
| | - Shouyang Yu
- Neuroscience & Metabolism Research, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610041, People's Republic of China
| | - Lanlan Jia
- Neuroscience & Metabolism Research, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610041, People's Republic of China
| | - Mina Chen
- Neuroscience & Metabolism Research, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University and Collaborative Innovation Center, Chengdu 610041, People's Republic of China
| | - Paul F Worley
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Bo Xiao
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518005, People's Republic of China;
- Department of Biology, School of Life Sciences, Brain Research Center, Southern University of Science and Technology, Shenzhen 518000, People's Republic of China
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5
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Electrospun Microfibers Modulate Intracellular Amino Acids in Liver Cells via Integrin β1. Bioengineering (Basel) 2021; 8:bioengineering8070088. [PMID: 34206385 PMCID: PMC8301164 DOI: 10.3390/bioengineering8070088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/14/2021] [Accepted: 06/18/2021] [Indexed: 11/16/2022] Open
Abstract
Although numerous recent studies have shown the importance of polymeric microfibrous extracellular matrices (ECMs) in maintaining cell behaviors and functions, the mechanistic nexus between ECMs and intracellular activities is largely unknown. Nevertheless, this knowledge will be critical in understanding and treating diseases with ECM remodeling. Therefore, we present our findings that ECM microstructures could regulate intracellular amino acid levels in liver cells mechanistically through integrin β1. Amino acids were studied because they are the fundamental blocks for protein synthesis and metabolism, two vital functions of liver cells. Two ECM conditions, flat and microfibrous, were prepared and studied. In addition to characterizing cell growth, albumin production, urea synthesis, and cytochrome p450 activity, we found that the microfibrous ECM generally upregulated the intracellular amino acid levels. Further explorations showed that cells on the flat substrate expressed more integrin β1 than cells on the microfibers. Moreover, after partially blocking integrin β1 in cells on the flat substrate, the intracellular amino acid levels were restored, strongly supporting integrin β1 as the linking mechanism. This is the first study to report that a non-biological polymer matrix could regulate intracellular amino acid patterns through integrin. The results will help with future therapy development for liver diseases with ECM changes (e.g., fibrosis).
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6
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Abstract
Radiolabeled amino acid uptake assays are a highly sensitive method used to characterize the uptake of amino acids by cells or tissues in culture. This method is an excellent tool to quantify changes in amino acid consumption that are associated with states of cellular differentiation and/or disease. The methods presented here can be adapted to measure the transport of all amino acids and can be applied to cultured cells and bone explants.
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Affiliation(s)
- Leyao Shen
- Department of Orthopaedic Surgery, Duke University School of Medicine, Duke University, Durham, NC, USA
| | - Courtney M Karner
- Department of Orthopaedic Surgery, Duke University School of Medicine, Duke University, Durham, NC, USA.
- Department of Cell Biology, Duke Orthopaedic, Cellular, Developmental and Genome Laboratories, Duke University School of Medicine, Duke University, Durham, NC, USA.
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7
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Hu G, Yu Y, Tang YJ, Wu C, Long F, Karner CM. The Amino Acid Sensor Eif2ak4/GCN2 Is Required for Proliferation of Osteoblast Progenitors in Mice. J Bone Miner Res 2020; 35:2004-2014. [PMID: 32453500 PMCID: PMC7688563 DOI: 10.1002/jbmr.4091] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 05/01/2020] [Accepted: 05/13/2020] [Indexed: 12/16/2022]
Abstract
Skeletal stem/progenitor cells (SSPC) are critical regulators of bone homeostasis by providing a continuous supply of osteoblasts throughout life. In response to inductive signals, SSPC proliferate before osteoblast differentiation. Proliferation requires the duplication of all cellular components before cell division. This imposes a unique biosynthetic requirement for amino acids that can be used for biomass production. Thus, the ability to sense and respond to amino acid availability is likely a major determinant for proliferation. Using a cellular and genetic approach, we demonstrate the amino acid sensor GCN2 is required to support the robust proliferative capacity of SSPC during bone homeostasis. GCN2 ablation results in decreased postnatal bone mass due primarily to reduced osteoblast numbers. Decreased osteoblast numbers is likely attributed to reduced SSPC proliferation as loss of GCN2 specifically affected proliferation in cultured bone marrow stromal cells (BMSCs) without impacting osteoblast differentiation in vitro. Mechanistically, GCN2 regulates proliferation by increasing amino acid uptake downstream of the transcriptional effector ATF4. Collectively, these data suggest amino acid sensing through the GCN2/ATF4 pathway is indispensable for robust SSPC proliferation necessary for bone homeostasis. © 2020 American Society for Bone and Mineral Research.
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Affiliation(s)
- Guoli Hu
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA
| | - Yilin Yu
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA
| | - Yuning J Tang
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA.,Department of Biology, Stanford University, Stanford, CA, USA
| | - Colleen Wu
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA.,Department of Cell Biology, Duke University School of Medicine, Durham, NC, USA
| | - Fanxin Long
- Department of Orthopaedic Surgery, Translational Research Program in Pediatric Orthopaedics, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA
| | - Courtney M Karner
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA.,Department of Cell Biology, Duke University School of Medicine, Durham, NC, USA
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8
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A negative reciprocal regulatory axis between cyclin D1 and HNF4α modulates cell cycle progression and metabolism in the liver. Proc Natl Acad Sci U S A 2020; 117:17177-17186. [PMID: 32631996 DOI: 10.1073/pnas.2002898117] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Hepatocyte nuclear factor 4α (HNF4α) is a master regulator of liver function and a tumor suppressor in hepatocellular carcinoma (HCC). In this study, we explore the reciprocal negative regulation of HNF4α and cyclin D1, a key cell cycle protein in the liver. Transcriptomic analysis of cultured hepatocyte and HCC cells found that cyclin D1 knockdown induced the expression of a large network of HNF4α-regulated genes. Chromatin immunoprecipitation-sequencing (ChIP-seq) demonstrated that cyclin D1 inhibits the binding of HNF4α to thousands of targets in the liver, thereby diminishing the expression of associated genes that regulate diverse metabolic activities. Conversely, acute HNF4α deletion in the liver induces cyclin D1 and hepatocyte cell cycle progression; concurrent cyclin D1 ablation blocked this proliferation, suggesting that HNF4α maintains proliferative quiescence in the liver, at least, in part, via repression of cyclin D1. Acute cyclin D1 deletion in the regenerating liver markedly inhibited hepatocyte proliferation after partial hepatectomy, confirming its pivotal role in cell cycle progression in this in vivo model, and enhanced the expression of HNF4α target proteins. Hepatocyte cyclin D1 gene ablation caused markedly increased postprandial liver glycogen levels (in a HNF4α-dependent fashion), indicating that the cyclin D1-HNF4α axis regulates glucose metabolism in response to feeding. In AML12 hepatocytes, cyclin D1 depletion led to increased glucose uptake, which was negated if HNF4α was depleted simultaneously, and markedly elevated glycogen synthesis. To summarize, mutual repression by cyclin D1 and HNF4α coordinately controls the cell cycle machinery and metabolism in the liver.
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Wu H, Ploeger JM, Kamarajugadda S, Mashek DG, Mashek MT, Manivel JC, Shekels LL, Lapiro JL, Albrecht JH. Evidence for a Novel Regulatory Interaction Involving Cyclin D1, Lipid Droplets, Lipolysis, and Cell Cycle Progression in Hepatocytes. Hepatol Commun 2019; 3:406-422. [PMID: 30859152 PMCID: PMC6396375 DOI: 10.1002/hep4.1316] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 12/22/2018] [Indexed: 12/12/2022] Open
Abstract
During normal proliferation, hepatocytes accumulate triglycerides (TGs) in lipid droplets (LDs), but the underlying mechanisms and functional significance of this steatosis are unknown. In the current study, we examined the coordinated regulation of cell cycle progression and LD accumulation. As previously shown, hepatocytes develop increased LD content after mitogen stimulation. Cyclin D1, in addition to regulating proliferation, was both necessary and sufficient to promote LD accumulation in response to mitogens. Interestingly, cyclin D1 promotes LD accumulation by inhibiting the breakdown of TGs by lipolysis through a mechanism involving decreased lipophagy, the autophagic degradation of LDs. To examine whether inhibition of lipolysis is important for cell cycle progression, we overexpressed adipose TG lipase (ATGL), a key enzyme involved in TG breakdown. As expected, ATGL reduced LD content but also markedly inhibited hepatocyte proliferation, suggesting that lipolysis regulates a previously uncharacterized cell cycle checkpoint. Consistent with this, in mitogen-stimulated cells with small interfering RNA-mediated depletion of cyclin D1 (which inhibits proliferation and stimulates lipolysis), concurrent ATGL knockdown restored progression into S phase. Following partial hepatectomy, a model of robust hepatocyte proliferation in vivo, ATGL overexpression led to decreased LD content, cell cycle inhibition, and marked liver injury, further indicating that down-regulation of lipolysis is important for normal hepatocyte proliferation. Conclusion: We suggest a new relationship between steatosis and proliferation in hepatocytes: cyclin D1 inhibits lipolysis, resulting in LD accumulation, and suppression of lipolysis is necessary for cell cycle progression.
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Affiliation(s)
- Heng Wu
- Gastroenterology DivisionMinneapolis VA Health Care SystemMinneapolisMN
- Division of Gastroenterology, Hepatology, and NutritionUniversity of MinnesotaMinneapolisMN
| | - Jonathan M. Ploeger
- Department of Biochemistry, Molecular Biology, and BiophysicsUniversity of MinnesotaMinneapolisMN
| | | | - Douglas G. Mashek
- Department of Biochemistry, Molecular Biology, and BiophysicsUniversity of MinnesotaMinneapolisMN
| | - Mara T. Mashek
- Department of Biochemistry, Molecular Biology, and BiophysicsUniversity of MinnesotaMinneapolisMN
| | - Juan C. Manivel
- Department of PathologyMinneapolis VA Health Care SystemMinneapolisMN
| | - Laurie L. Shekels
- Gastroenterology DivisionMinneapolis VA Health Care SystemMinneapolisMN
| | - Jessica L. Lapiro
- Gastroenterology DivisionMinneapolis VA Health Care SystemMinneapolisMN
- Division of Gastroenterology, Hepatology, and NutritionUniversity of MinnesotaMinneapolisMN
| | - Jeffrey H. Albrecht
- Gastroenterology DivisionMinneapolis VA Health Care SystemMinneapolisMN
- Division of Gastroenterology, Hepatology, and NutritionUniversity of MinnesotaMinneapolisMN
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Fang H, Zhang AH, Sun H, Yu JB, Wang L, Wang XJ. High-throughput metabolomics screen coupled with multivariate statistical analysis identifies therapeutic targets in alcoholic liver disease rats using liquid chromatography-mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2019; 1109:112-120. [PMID: 30743140 DOI: 10.1016/j.jchromb.2019.01.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 12/17/2018] [Accepted: 01/24/2019] [Indexed: 12/18/2022]
Abstract
Identification of metabolic alterations is useful for elucidating the pathophysiology and mass spectrometry-aided metabolomic, which provides small molecule metabolites to understand underlying mechanisms of complex diseases. In this work, we developed a novel liquid chromatography coupled with tandem mass spectrometry-based metabolomics screen coupled with multivariate statistical analysis workflow to obtaining the metabolite annotation, visualization and rapid characterization of small molecular metabolites, then revealed the altered metabolic pathway in a rat model of alcohol-induced liver damage rats as case study. The ions were detected in both positive and negative mode, and the key biomarkers were selected through multivariate statistical screening analysis. We employed the enhanced mass spectrometry coverage method to comprehensive analysis of the metabolite data. Importantly, we further find these small molecule metabolites were associated with multiple metabolic pathways. The elucidation of these altered metabolic pathways should help identify new and specific therapeutic targets. In addition, this metabolomics workflow coupled to LC-MS/MS has been successfully applied to the identification of small molecule metabolites in this complex disease. We strongly believe that metabolomics studies will benefit from incorporating liquid chromatography coupled with tandem mass spectrometry strategies.
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Affiliation(s)
- Heng Fang
- National Chinmedomics Research Center, Sino-America Chinmedomics Technology Collaboration Center, National TCM Key Laboratory of Serum Pharmacochemistry, Laboratory of Metabolomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Heping Road 24, Harbin, China
| | - Ai-Hua Zhang
- National Chinmedomics Research Center, Sino-America Chinmedomics Technology Collaboration Center, National TCM Key Laboratory of Serum Pharmacochemistry, Laboratory of Metabolomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Heping Road 24, Harbin, China
| | - Hui Sun
- National Chinmedomics Research Center, Sino-America Chinmedomics Technology Collaboration Center, National TCM Key Laboratory of Serum Pharmacochemistry, Laboratory of Metabolomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Heping Road 24, Harbin, China
| | - Jing-Bo Yu
- National Chinmedomics Research Center, Sino-America Chinmedomics Technology Collaboration Center, National TCM Key Laboratory of Serum Pharmacochemistry, Laboratory of Metabolomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Heping Road 24, Harbin, China
| | - Liang Wang
- National Chinmedomics Research Center, Sino-America Chinmedomics Technology Collaboration Center, National TCM Key Laboratory of Serum Pharmacochemistry, Laboratory of Metabolomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Heping Road 24, Harbin, China
| | - Xi-Jun Wang
- National Chinmedomics Research Center, Sino-America Chinmedomics Technology Collaboration Center, National TCM Key Laboratory of Serum Pharmacochemistry, Laboratory of Metabolomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Heping Road 24, Harbin, China.
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11
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Bufadienolides from Venenum Bufonis Inhibit mTOR-Mediated Cyclin D1 and Retinoblastoma Protein Leading to Arrest of Cell Cycle in Cancer Cells. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2018; 2018:3247402. [PMID: 30108651 PMCID: PMC6077658 DOI: 10.1155/2018/3247402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/15/2018] [Accepted: 06/13/2018] [Indexed: 02/08/2023]
Abstract
Objective Bufadienolides, the main components in Venenum Bufonis secreted from toads, have been proved to be with significant anticancer activity aside from the positive inotropic action as cardenolides. Here an underlying anticancer mechanism was further elucidated for an injection made from Venenum Bufonis containing nine bufadienolides. Methods One solution reagent and cell cycle analyses were for determining effect of bufadienolides on cancer cells. Western blotting was used for protein expression. Results Bufadienolides inhibit cell proliferation and arrest cells in G1 phase. Bufadienolides also inhibit the mammalian target of rapamycin (mTOR) signaling pathway, which is evidenced by the data that bufadienolides inhibit type I insulin-like growth factor- (IGF-1-) activated phosphorylation of mTOR by a concentration- and time-dependent way, as well as phosphorylation of p70 S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E (eIF4E) binding protein 1 (4E-BP1). Subsequent results indicated that cyclin D1 expression and phosphorylation of retinoblastoma protein (Rb)—two characterized regulators in cell cycle of G1—are also inhibited and the process is dependent on mTOR pathway. Conclusion Bufadienolides inhibit proliferation partially due to arresting cell cycle in G1 phase, which is mediated by inhibiting mTOR-cyclin D1/Rb signal pathway.
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Kamarajugadda S, Becker JR, Hanse EA, Mashek DG, Mashek MT, Hendrickson AM, Mullany LK, Albrecht JH. Cyclin D1 represses peroxisome proliferator-activated receptor alpha and inhibits fatty acid oxidation. Oncotarget 2018; 7:47674-47686. [PMID: 27351284 PMCID: PMC5216970 DOI: 10.18632/oncotarget.10274] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 06/04/2016] [Indexed: 01/27/2023] Open
Abstract
Cyclin D1 is a cell cycle protein that promotes proliferation by mediating progression through key checkpoints in G1 phase. It is also a proto-oncogene that is commonly overexpressed in human cancers. In addition to its canonical role in controlling cell cycle progression, cyclin D1 affects other aspects of cell physiology, in part through transcriptional regulation. In this study, we find that cyclin D1 inhibits the activity of a key metabolic transcription factor, peroxisome proliferator-activated receptor α (PPARα), a member of nuclear receptor family that induces fatty acid oxidation and may play an anti-neoplastic role. In primary hepatocytes, cyclin D1 inhibits PPARα transcriptional activity and target gene expression in a cdk4-independent manner. In liver and breast cancer cells, knockdown of cyclin D1 leads to increased PPARα transcriptional activity, expression of PPARα target genes, and fatty acid oxidation. Similarly, cyclin D1 depletion enhances binding of PPARα to target sequences by chromatin immunoprecipitation. In proliferating hepatocytes and regenerating liver in vivo, induction of endogenous cyclin D1 is associated with diminished PPARα activity. Cyclin D1 expression is both necessary and sufficient for growth factor-mediated repression of fatty acid oxidation in proliferating hepatocytes. These studies indicate that in addition to playing a pivotal role in cell cycle progression, cyclin D1 represses PPARα activity and inhibits fatty acid oxidation. Our findings establish a new link between cyclin D1 and metabolism in both tumor cells and physiologic hepatocyte proliferation.
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Affiliation(s)
- Sushama Kamarajugadda
- Gastroenterology Division, Minneapolis VA Health Care System, Minneapolis, MN 55417, USA
| | - Jennifer R Becker
- Minneapolis Medical Research Foundation, Minneapolis, MN, 55404, USA
| | - Eric A Hanse
- Minneapolis Medical Research Foundation, Minneapolis, MN, 55404, USA
| | - Douglas G Mashek
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mara T Mashek
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Lisa K Mullany
- Minneapolis Medical Research Foundation, Minneapolis, MN, 55404, USA
| | - Jeffrey H Albrecht
- Gastroenterology Division, Minneapolis VA Health Care System, Minneapolis, MN 55417, USA
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Abstract
Liver possesses many critical functions such as synthesis, detoxification, and metabolism. It continually receives nutrient-rich blood from gut, which incidentally is also toxin-rich. That may be why liver is uniquely bestowed with a capacity to regenerate. A commonly studied procedure to understand the cellular and molecular basis of liver regeneration is that of surgical resection. Removal of two-thirds of the liver in rodents or patients instigates alterations in hepatic homeostasis, which are sensed by the deficient organ to drive the restoration process. Although the exact mechanisms that initiate regeneration are unknown, alterations in hemodynamics and metabolism have been suspected as important effectors. Key signaling pathways are activated that drive cell proliferation in various hepatic cell types through autocrine and paracrine mechanisms. Once the prehepatectomy mass is regained, the process of regeneration is adequately terminated. This review highlights recent discoveries in the cellular and molecular basis of liver regeneration.
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Affiliation(s)
- Morgan E. Preziosi
- Division of Experimental Pathology, Department of Pathology, University of Pittsburgh, School of Medicine and University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania,Pittsburgh Liver Research Center, University of Pittsburgh, School of Medicine and University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Satdarshan P. Monga
- Division of Experimental Pathology, Department of Pathology, University of Pittsburgh, School of Medicine and University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania,Pittsburgh Liver Research Center, University of Pittsburgh, School of Medicine and University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania,Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, University of Pittsburgh, School of Medicine and University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
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Sayano T, Kawano Y, Kusada W, Arimoto Y, Esaki K, Hamano M, Udono M, Katakura Y, Ogawa T, Kato H, Hirabayashi Y, Furuya S. Adaptive response to l-serine deficiency is mediated by p38 MAPK activation via 1-deoxysphinganine in normal fibroblasts. FEBS Open Bio 2016; 6:303-16. [PMID: 27239443 PMCID: PMC4821351 DOI: 10.1002/2211-5463.12038] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 01/20/2016] [Accepted: 01/27/2016] [Indexed: 11/17/2022] Open
Abstract
Reduced availability of l‐serine limits cell proliferation and leads to an adaptation to l‐serine‐deficient environment, the underlying molecular mechanism of which remain largely unexplored. Genetic ablation of 3‐phosphoglycerate dehydrogenase (Phgdh), which catalyzes the first step of de novo l‐serine synthesis, led to diminished cell proliferation and the activation of p38 MAPK and stress‐activated protein kinase/Jun amino‐terminal kinase in mouse embryonic fibroblasts under l‐serine depletion. The resultant l‐serine deficiency induced cyclin‐dependent kinase inhibitor 1a (Cdkn1a; p21) expression, which was mediated by p38 MAPK. Survival of the Phgdh‐deficient mouse embryonic fibroblasts was markedly reduced by p38 MAPK inhibition under l‐serine depletion, whereas p38 MAPK could be activated by 1‐deoxysphinganine, an atypical alanine‐derived sphingoid base that was found to accumulate in l‐serine‐depleted mouse embryonic fibroblasts. These observations provide persuasive evidence that when the external l‐serine supply is limited, l‐serine synthesized de novo in proliferating cells serves as a metabolic gatekeeper to maintain cell survival and the functions necessary for executing cell cycle progression. Database Gene Expression Omnibus, accession number GSE55687.
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Affiliation(s)
- Tomoko Sayano
- Laboratory of Functional Genomics and Metabolism Department of Innovative Science and Technology for Bio-industry Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan; Laboratory for Molecular Membrane Neuroscience RIKEN Brain Science Institute Wako Saitama Japan
| | - Yuki Kawano
- Department of Bioscience and Biotechnology Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan
| | - Wataru Kusada
- Department of Bioscience and Biotechnology Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan
| | - Yashiho Arimoto
- Department of Bioscience and Biotechnology Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan
| | - Kayoko Esaki
- Laboratory of Functional Genomics and Metabolism Department of Innovative Science and Technology for Bio-industry Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan; Laboratory for Molecular Membrane Neuroscience RIKEN Brain Science Institute Wako Saitama Japan
| | - Momoko Hamano
- Department of Bioscience and Biotechnology Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan
| | - Miyako Udono
- Department of Genetic Resources Technology Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan
| | - Yoshinori Katakura
- Department of Genetic Resources Technology Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan
| | - Takuya Ogawa
- Department of Pharmaceutical Sciences International University of Health and Welfare Tochigi Japan
| | - Hisanori Kato
- Corporate Sponsored Research Program 'Food for Life', Organization for Interdisciplinary Research Projects The University of Tokyo Japan
| | - Yoshio Hirabayashi
- Laboratory for Molecular Membrane Neuroscience RIKEN Brain Science Institute Wako Saitama Japan
| | - Shigeki Furuya
- Laboratory of Functional Genomics and Metabolism Department of Innovative Science and Technology for Bio-industry Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan; Department of Bioscience and Biotechnology Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan; Department of Genetic Resources Technology Graduate School of Bioresource and Bioenvironmental Sciences Kyushu University Fukuoka Japan
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Rieswijk L, Brauers KJJ, Coonen MLJ, van Breda SGJ, Jennen DGJ, Kleinjans JCS. Evaluating microRNA profiles reveals discriminative responses following genotoxic or non-genotoxic carcinogen exposure in primary mouse hepatocytes. Mutagenesis 2015; 30:771-84. [DOI: 10.1093/mutage/gev036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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Wang G, Zhang J, Wang G, Fan X, Sun X, Qin H, Xu N, Zhong M, Qiao Z, Tang Y, Song R. Proline responding1 Plays a Critical Role in Regulating General Protein Synthesis and the Cell Cycle in Maize. THE PLANT CELL 2014; 26:2582-2600. [PMID: 24951479 PMCID: PMC4114953 DOI: 10.1105/tpc.114.125559] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 05/19/2014] [Accepted: 05/29/2014] [Indexed: 05/18/2023]
Abstract
Proline, an important amino acid, accumulates in many plant species. Besides its role in plant cell responses to environmental stresses, the potential biological functions of proline in growth and development are unclear. Here, we report cloning and functional characterization of the maize (Zea mays) classic mutant proline responding1 (pro1) gene. This gene encodes a Δ1-pyrroline-5- carboxylate synthetase that catalyzes the biosynthesis of proline from glutamic acid. Loss of function of Pro1 significantly inhibits proline biosynthesis and decreases its accumulation in the pro1 mutant. Proline deficiency results in an increased level of uncharged tRNApro AGG accumulation and triggers the phosphorylation of eukaryotic initiation factor 2α (eIF2α) in the pro1 mutant, leading to a general reduction in protein synthesis in this mutant. Proline deficiency also downregulates major cyclin genes at the transcriptional level, causing cell cycle arrest and suppression of cell proliferation. These processes are reversible when external proline is supplied to the mutant, suggesting that proline plays a regulatory role in the cell cycle transition. Together, the results demonstrate that proline plays an important role in the regulation of general protein synthesis and the cell cycle transition in plants.
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Affiliation(s)
- Gang Wang
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China Coordinated Crop Biology Research Center, Beijing 100193, P.R. China
| | - Jushan Zhang
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Guifeng Wang
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China Coordinated Crop Biology Research Center, Beijing 100193, P.R. China
| | - Xiangyu Fan
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Xin Sun
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Hongli Qin
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Nan Xu
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Mingyu Zhong
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Zhenyi Qiao
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Yuanping Tang
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Rentao Song
- Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China Coordinated Crop Biology Research Center, Beijing 100193, P.R. China
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17
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Kumar S, Zou Y, Bao Q, Wang M, Dai G. Proteomic analysis of immediate-early response plasma proteins after 70% and 90% partial hepatectomy. Hepatol Res 2013; 43:876-89. [PMID: 23279269 PMCID: PMC4354878 DOI: 10.1111/hepr.12030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/18/2012] [Accepted: 11/20/2012] [Indexed: 02/08/2023]
Abstract
AIM Partial hepatectomy (PH) induces robust hepatic regenerative and metabolic responses that are considered to be triggered by humoral factors. The aim of the study was to identify plasma protein factors that potentially trigger or reflect the body's immediate-early responses to liver mass reduction. METHODS Male C57BL/6 mice were subjected to sham operation, 70% PH or 90% PH. Blood was collected from the inferior vena cava at 20, 60 and 180 min after surgery. RESULTS Using a label-free quantitative mass spectrometry-based proteomics approach, we identified 399 proteins exhibiting significant changes in plasma expression between any two groups. Of the 399 proteins, 167 proteins had multiple unique sequences and high peptide ID confidence (>90%) and were defined as priority 1 proteins. A group of plasma proteins largely associated with metabolism is enriched after 70% PH. Among the plasma proteins that respond to 90% PH are a dominant group of proteins that are also associated with metabolism and one known cytokine (platelet factor 4). Ninety percent PH and 70% PH induces similar changes in plasma protein profile. CONCLUSION Our findings enable us to gain insight into the immediate-early response of plasma proteins to liver mass loss. Our data support the notion that increased metabolic demands of the body after massive liver mass loss may function as a sensor that calibrates hepatic regenerative response.
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Affiliation(s)
- Sudhanshu Kumar
- Department of Biology, School of Science, Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indiana
| | - Yuhong Zou
- Department of Biology, School of Science, Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indiana
| | - Qi Bao
- Department of Biology, School of Science, Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indiana
| | - Mu Wang
- Department of Biochemistry and Molecular Biology, School of Medicine, Indiana University, Indianapolis, Indiana
| | - Guoli Dai
- Department of Biology, School of Science, Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indiana
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18
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Shan J, Hamazaki T, Tang TA, Terada N, Kilberg MS. Activation of the amino acid response modulates lineage specification during differentiation of murine embryonic stem cells. Am J Physiol Endocrinol Metab 2013; 305:E325-35. [PMID: 23736538 PMCID: PMC4116408 DOI: 10.1152/ajpendo.00136.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In somatic cells, a collection of signaling pathways activated by amino acid limitation have been identified and referred to as the amino acid response (AAR). Despite the importance of possible detrimental effects of nutrient limitation during in vitro culture, the AAR has not been investigated in embryonic stem cells (ESC). AAR activation caused the expected increase in transcription factors that mediate specific AAR pathways, as well as the induction of asparagine synthetase, a terminal AAR target gene. Neither AAR activation nor stable knockdown of activating transcription factor (Atf) 4, a transcriptional mediator of the AAR, adversely affected ESC self-renewal or pluripotency. Low-level induction of the AAR over a 12-day period of embryoid body differentiation did alter lineage specification such that the primitive endodermal, visceral endodermal, and endodermal lineages were favored, whereas mesodermal and certain ectodermal lineages were suppressed. Knockdown of Atf4 further enhanced the AAR-induced increase in endodermal formation, suggesting that this phenomenon is mediated by an Atf4-independent mechanism. Collectively, the results indicate that, during differentiation of mouse embryoid bodies in culture, the availability of nutrients, such as amino acids, can influence the formation of specific cell lineages.
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Affiliation(s)
- Jixiu Shan
- Department of Biochemistry and Molecular Biology, McKnight Brain Institute, Shands Cancer Center, and Center for Nutritional Sciences, University of Florida College of Medicine, Gainesville, Florida, USA
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Salehi S, Brereton HC, Arno MJ, Darling D, Quaglia A, O'Grady J, Heaton N, Aluvihare VR. Human liver regeneration is characterized by the coordinated expression of distinct microRNA governing cell cycle fate. Am J Transplant 2013; 13:1282-95. [PMID: 23465054 DOI: 10.1111/ajt.12183] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 01/10/2013] [Accepted: 01/14/2013] [Indexed: 01/25/2023]
Abstract
In the absence of adequate compensatory regeneration, overwhelming liver damage can cause acute liver failure (ALF) and death without emergent liver transplantation (LT). Auxiliary LT produces satisfactory outcomes in this setting, with the prospect of native liver regeneration sustaining long-term survival. Since animal models only partially recapitulate human liver regeneration, we investigated the molecular mechanisms controlling it in this unique LT setting, as an exemplar of human liver regeneration. We demonstrate coordinated changes in expression of microRNA (miRNA) during regeneration that drive proliferation, innate immunity and angiogenesis. In contrast, failed regeneration in a similar cohort is associated with distinct miRNA enforcing cell cycle inhibition and DNA methylation. The miRNA expression associated with successful or failed regeneration when recapitulated in vitro, triggered expression of cardinal regeneration-linked genes promoting cell cycle entry or inhibition, respectively. Furthermore, inhibition of miRNA 150, 663 and 503, whose downregulation is associated with successful regeneration, induced cell proliferation which a key determinant of successful regeneration. Our data indicate that human liver regeneration may be orchestrated by distinct miRNA controlling key regeneration-linked processes including hepatocyte proliferation. To our knowledge this is the first characterization of molecular processes associated with human liver regeneration.
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Affiliation(s)
- S Salehi
- Institute of Liver Studies, King's College Hospital, London, United Kingdom
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20
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Up-regulation of cyclin-E(1) via proline-mTOR pathway is responsible for HGF-mediated G(1)/S progression in the primary culture of rat hepatocytes. Biochem Biophys Res Commun 2013; 435:120-5. [PMID: 23618858 DOI: 10.1016/j.bbrc.2013.04.052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 04/10/2013] [Indexed: 12/27/2022]
Abstract
Hepatocyte growth factor (HGF) is a key ligand that elicits G1/S progression of epithelial cells, including hepatocytes. Proline is also required for DNA synthesis that is induced by growth factors in primary culture of hepatocytes. However, it remains unknown how proline contributes to the G1/S progression of hepatocytes. The primary culture of rat hepatocytes using HGF plus proline can be a conceptual model for elucidating the molecular linkage of amino acids and growth factors during G1/S progression. Using this in vitro model, we provide evidence that not only induction of cyclin-D1 by HGF but also up-regulation of cyclin-E1 by proline is required for hepatocytes to enter the S-phase. Proline-enhanced cyclin-E1 induction, without changing its mRNA level, is associated with the activation of mammalian target of rapamycin (mTOR)-dependent pathways. Indeed, proline enhanced the ribosomal protein S6 phosphorylations (i.e., mTOR target), concomitantly with an increase in cyclin-E1. Inversely, mTOR-inhibitor, rapamycin suppressed the proline-mediated induction of cyclin-E1. As a result, DNA synthesis of hepatocytes, which was induced by HGF in the presence of proline, was largely abolished by mTOR-inhibitor treatment. Such a co-mitogenic effect of proline was also dependent on collagen synthesis: collagen synthesis inhibitors, such as cis-OH-proline, diminished the proline-induced cyclin-E1, and then the G1/S progression of hepatocytes was also suppressed. Overall, proline-mediated mTOR activation and collagen synthesis were found critical for HGF-induced DNA synthesis, partly via the sufficient accumulation of cyclin-E1. This is the first report to demonstrate the molecular bridge between amino acids and growth factors that drive mitogenic outcomes.
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CD98 increases renal epithelial cell proliferation by activating MAPKs. PLoS One 2012; 7:e40026. [PMID: 22768207 PMCID: PMC3386947 DOI: 10.1371/journal.pone.0040026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 05/31/2012] [Indexed: 12/22/2022] Open
Abstract
CD98 heavy chain (CD98hc) is a multifunctional transmembrane spanning scaffolding protein whose extracellular domain binds with light chain amino acid transporters (Lats) to form the heterodimeric amino acid transporters (HATs). It also interacts with β1 and β3 integrins by its transmembrane and cytoplasmic domains. This interaction is proposed to be the mechanism whereby CD98 mediates cell survival and growth via currently undefined signaling pathways. In this study, we determined whether the critical function of CD98-dependent amino acid transport also plays a role in cell proliferation and defined the signaling pathways that mediate CD98-dependent proliferation of murine renal inner medullary collecting duct (IMCD) cells. We demonstrate that downregulating CD98hc expression resulted in IMCD cell death. Utilizing overexpression studies of CD98hc mutants that either lacked a cytoplasmic tail or were unable to bind to Lats we showed that CD98 increases serum-dependent cell proliferation by a mechanism that requires the CD98hc cytoplasmic tail. We further demonstrated that CD98-dependent amino acid transport increased renal tubular epithelial cell proliferation by a mechanism that does not require the CD98hc cytoplasmic tail. Both these mechanisms of increased renal tubular epithelial cell proliferation are mediated by Erk and p38 MAPK signaling. Although increased amino transport markedly activated mTor signaling, this pathway did not alter cell proliferation. Thus, these studies demonstrate that in IMCD cells, the cytoplasmic and extracellular domains of CD98hc regulate cell proliferation by distinct mechanisms that are mediated by common MAPK signaling pathways.
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Gran P, Cameron-Smith D. The actions of exogenous leucine on mTOR signalling and amino acid transporters in human myotubes. BMC PHYSIOLOGY 2011; 11:10. [PMID: 21702994 PMCID: PMC3141572 DOI: 10.1186/1472-6793-11-10] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 06/25/2011] [Indexed: 01/18/2023]
Abstract
Background The branched-chain amino acid (BCAA) leucine has been identified to be a key regulator of skeletal muscle anabolism. Activation of anabolic signalling occurs via the mammalian target of rapamycin (mTOR) through an undefined mechanism. System A and L solute carriers transport essential amino acids across plasma membranes; however it remains unknown whether an exogenous supply of leucine regulates their gene expression. The aim of the present study was to investigate the effects of acute and chronic leucine stimulation of anabolic signalling and specific amino acid transporters, using cultured primary human skeletal muscle cells. Results Human myotubes were treated with leucine, insulin or co-treated with leucine and insulin for 30 min, 3 h or 24 h. Activation of mTOR signalling kinases were examined, together with putative nutrient sensor human vacuolar protein sorting 34 (hVps34) and gene expression of selected amino acid transporters. Phosphorylation of mTOR and p70S6K was transiently increased following leucine exposure, independently to insulin. hVps34 protein expression was also significantly increased. However, genes encoding amino acid transporters were differentially regulated by insulin and not leucine. Conclusions mTOR signalling is transiently activated by leucine within human myotubes independently of insulin stimulation. While this occurred in the absence of changes in gene expression of amino acid transporters, protein expression of hVps34 increased.
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Affiliation(s)
- Petra Gran
- Molecular Nutrition Unit, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
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Zhou F, Wang Y, Guan Y, Xu Y, Gao X, Wu W, Ye B. Construction and characterization of a cDNA library from shark regenerated hepatic tissue. FISH & SHELLFISH IMMUNOLOGY 2011; 30:1170-1177. [PMID: 21382499 DOI: 10.1016/j.fsi.2011.02.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 02/21/2011] [Accepted: 02/26/2011] [Indexed: 05/30/2023]
Abstract
Sharks are a type of fish with a full cartilaginous skeleton and have big livers. To better understand liver regeneration in sharks and screening for the important genes participated in disease-defense, in this study, a cDNA library of regenerated liver tissues of shark, Chiloscyllium plagiosum, was constructed. A total of 2103 expressed sequence tags (ESTs), which represents 997 unique genes, were sequenced. Among these genes, 434 (43.53%) of them showed significant similarity (E-values < 10⁻⁵) to the sequences in NCBI Nt database, 685 (68.71%) of these unique genes showed significant similarity (E-values < 10⁻⁵) to the sequences in NCBI Nr database, and 662 (66.40%) of these unique genes showed significant similarity (E-values < 10⁻⁵) to the Swiss-Prot database. Preliminary analysis of unique genes according to COG database showed that unigenes were further grouped into 21 functional categories including inorganic ion transport and metabolism, energy production and conversion, posttranslational modification, protein turnover and chaperones, general function prediction only, translation, and ribosomal structure and biogenesis. Several possible candidate genes involved in liver regeneration were selected to analyze their expression with relative quantification real-time PCR. This study may contribute to our better understanding of the molecular mechanism of regeneration in shark liver. Furthermore, the EST cataloguing and profiling of shark will be also benefited to the functional genomic research in this marine species.
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Affiliation(s)
- Feng Zhou
- School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, PR China
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A model of liver regeneration. Biophys J 2009; 96:3926-35. [PMID: 19450465 DOI: 10.1016/j.bpj.2009.01.061] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 01/07/2009] [Accepted: 01/08/2009] [Indexed: 12/29/2022] Open
Abstract
The network of interactions underlying liver regeneration is robust and precise with liver resections resulting in controlled hyperplasia (cell proliferation) that terminates when the liver regains its lost mass. The interplay of cytokines and growth factors responsible for the inception and termination of this hyperplasia is not well understood. A model is developed for this network of interactions based on the known data of liver resections. This model reproduces the relevant published data on liver regeneration and provides geometric insights into the experimental observations. The predictions of this model are used to suggest two novel strategies for speeding up liver mass recovery and a strategy for enabling liver mass recovery in cases where a resection leaves <20% of the liver that would otherwise result in complete loss of liver mass.
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Yuan Y, Wu X, Ou Q, Gao J, Tennant BC, Han W, Yu Y. Differential expression of the genes involved in amino acids and nitrogen metabolisms during liver regeneration of mice. Hepatol Res 2009; 39:301-12. [PMID: 19067752 DOI: 10.1111/j.1872-034x.2008.00456.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM Liver regeneration is a highly coordinated response to hepatic injury or resection that is controlled by the body's overall requirement for liver function. The level of circulating amino acids in blood increases after acute liver injury and administration of amino acid mixtures induces hepatic DNA replication. These findings suggest a close connection between amino acid metabolism and hepatic proliferation. However, the underlying molecular mechanisms have not been completely elucidated. Here, we applied a cDNA micro-array technique to analyze expression profiles of the genes associated with nitrogen and amino acid metabolism during liver regeneration in mice following treatment with CCl(4). METHODS Seventy-nine genes were identified for their significantly altered expression patterns at different stages of liver damage and regeneration. RESULTS We observed that the numbers of down-regulated genes were remarkably higher than that of up-regulated genes at 1.5 days following carbon tetrachloride administration when hepatic DNA replication was most active, indicating the existence of a counter balance between cell proliferation and liver metabolism functions. CONCLUSIONS Our results suggest that suppression of amino acids metabolism after acute liver injury results in the accumulation of amino acids in plasma that serves as a driving force for liver regeneration.
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Affiliation(s)
- Yunsheng Yuan
- School of Agriculture and Biology, Shanghai Municipality Key Laboratory for Veterinary Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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Tomiya T, Omata M, Imamura H, Fujiwara K. Impaired liver regeneration in acute liver failure: the significance of cross-communication of growth associated factors in liver regeneration. Hepatol Res 2008; 38 Suppl 1:S29-33. [PMID: 19125948 DOI: 10.1111/j.1872-034x.2008.00423.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Liver regeneration is considered to be retarded or suppressed in patients with acute liver failure. However, the mechanisms for this suppression remain to be elucidated. In order to evaluate deficiencies in liver regeneration in patients with acute liver failure, we focused on the cross-communication of growth-associated factors in experimental models. In primary cultured rat hepatocytes, the levels of cellular p53 and transforming growth factor-alpha (TGF-alpha), as well as DNA synthesis increased by the addition of hepatocyte growth factor (HGF). When p53 activity was suppressed, TGF-alpha expression and DNA synthesis were reduced. DNA synthesis was also reduced when TGF-alpha activity was suppressed. In rats after partial hepatectomy, hepatic HGF and p53 protein levels increased, followed by an increase of hepatic TGF-alpha levels and hepatocyte proliferation. Circulating levels of HGF and TGF-alpha correlated with changes in the hepatic levels. The suppression of TGF-alpha activity reduced the proliferation of hepatocytes in these rats. In patients suffering from acute hepatitis, serum HGF levels increased followed by an increase of serum TGF-alpha levels. In contrast, in patients with acute liver failure, the increase of serum TGF-alpha levels was suppressed depending on the severity of hepatic failure, even though serum HGF levels markedly increased. The patients' hepatic levels were consistent with serum levels. Cross-communication of growth associated factors may be important in the progression of liver regeneration, and impaired regenerative capacity in patients with acute liver failure may be attributable, at least in part, to a disruption of communication of growth-associated factors.
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Affiliation(s)
- Tomoaki Tomiya
- Department of Gastroenterology, University of Tokyo, Tokyo, Japan
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Raven JF, Baltzis D, Wang S, Mounir Z, Papadakis AI, Gao HQ, Koromilas AE. PKR and PKR-like Endoplasmic Reticulum Kinase Induce the Proteasome-dependent Degradation of Cyclin D1 via a Mechanism Requiring Eukaryotic Initiation Factor 2α Phosphorylation. J Biol Chem 2008; 283:3097-3108. [PMID: 18063576 DOI: 10.1074/jbc.m709677200] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Jennifer F Raven
- Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec H2W 1S6, Canada; Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Dionissios Baltzis
- Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec H2W 1S6, Canada; Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Shuo Wang
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Zineb Mounir
- Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec H2W 1S6, Canada; Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Andreas I Papadakis
- Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec H2W 1S6, Canada; Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Hong Qing Gao
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Antonis E Koromilas
- Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec H2W 1S6, Canada; Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada.
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Nishikawa T, Tomiya T, Ohtomo N, Inoue Y, Ikeda H, Tejima K, Watanabe N, Tanoue Y, Omata M, Fujiwara K. Stimulation by glutamine and proline of HGF production in hepatic stellate cells. Biochem Biophys Res Commun 2007; 363:978-82. [DOI: 10.1016/j.bbrc.2007.09.082] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Accepted: 09/20/2007] [Indexed: 12/15/2022]
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29
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Mullany LK, Nelsen CJ, Hanse EA, Goggin MM, Anttila CK, Peterson M, Bitterman PB, Raghavan A, Crary GS, Albrecht JH. Akt-mediated liver growth promotes induction of cyclin E through a novel translational mechanism and a p21-mediated cell cycle arrest. J Biol Chem 2007; 282:21244-52. [PMID: 17517888 DOI: 10.1074/jbc.m702110200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The control of hepatocyte growth is relevant to the processes of liver regeneration, development, metabolic homeostasis, and cancer. A key component of growth control is the protein kinase Akt, which acts downstream of mitogens and nutrients to affect protein translation and cell cycle progression. In this study, we found that transient transfection of activated Akt triggered a 3-4-fold increase in liver size within days but only minimal hepatocyte proliferation. Akt-induced liver growth was associated with marked up-regulation of cyclin E but not cyclin D1. Analysis of liver polyribosomes demonstrated that the post-transcriptional induction of cyclin E was associated with increased translational efficiency of this mRNA, suggesting that cell growth promotes expression of this protein through a translational mechanism that is distinct from the cyclin D-E2F pathway. Treatment of Akt-transfected mice with rapamycin only partially inhibited liver growth and did not prevent the induction of cyclin E protein, indicating that target of rapamycin activity is not necessary for this response. In the enlarged livers, cyclin E-Cdk2 complexes were present in high abundance but were inactive due to increased binding of p21 to these complexes. Akt transfection of p21(-/-) mice promoted liver growth, activation of Cdk2, and enhanced hepatocyte proliferation. In conclusion, growth promotes cyclin E expression through a novel translational mechanism in the liver, suggesting a new link between cell growth and the cell cycle machinery. Furthermore, p21 suppresses proliferation in the overgrown livers and may play a role in preventing cell cycle progression in response to organ size homeostatic mechanisms.
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Affiliation(s)
- Lisa K Mullany
- Division of Gastroenterology, Hennepin County Medical Center, Minneapolis, Minnesota 55415, USA
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Gomez D, Homer-Vanniasinkam S, Graham AM, Prasad KR. Role of ischaemic preconditioning in liver regeneration following major liver resection and transplantation. World J Gastroenterol 2007; 13:657-70. [PMID: 17278187 PMCID: PMC4065997 DOI: 10.3748/wjg.v13.i5.657] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Liver ischaemic preconditioning (IPC) is known to protect the liver from the detrimental effects of ischaemic-reperfusion injury (IRI), which contributes significantly to the morbidity and mortality following major liver surgery. Recent studies have focused on the role of IPC in liver regeneration, the precise mechanism of which are not completely understood. This review discusses the current understanding of the mechanism of liver regeneration and the role of IPC in this setting. Relevant articles were reviewed from the published literature using the Medline database. The search was performed using the keywords “liver”, “ischaemic reperfusion”, “ischaemic preconditioning”, “regeneration”, “hepatectomy” and “transplantation”. The underlying mechanism of liver regeneration is a complex process involving the interaction of cytokines, growth factors and the metabolic demand of the liver. IPC, through various mediators, promotes liver regeneration by up-regulating growth-promoting factors and suppresses growth-inhibiting factors as well as damaging stresses. The increased understanding of the cellular mechanisms involved in IPC will enable the development of alternative treatment modalities aimed at promoting liver regeneration following major liver resection and transplantation.
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Affiliation(s)
- D Gomez
- Department of Hepatobiliary Surgery and Transplantation, St. James's University Hospital, Leeds LS9 7TF, UK
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31
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Leong HX, Simkevich C, Lesieur-Brooks A, Lau BW, Fugere C, Sabo E, Thompson NL. Short-term arginine deprivation results in large-scale modulation of hepatic gene expression in both normal and tumor cells: microarray bioinformatic analysis. Nutr Metab (Lond) 2006; 3:37. [PMID: 16961918 PMCID: PMC1613245 DOI: 10.1186/1743-7075-3-37] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Accepted: 09/08/2006] [Indexed: 12/02/2022] Open
Abstract
Background We have reported arginine-sensitive regulation of LAT1 amino acid transporter (SLC 7A5) in normal rodent hepatic cells with loss of arginine sensitivity and high level constitutive expression in tumor cells. We hypothesized that liver cell gene expression is highly sensitive to alterations in the amino acid microenvironment and that tumor cells may differ substantially in gene sets sensitive to amino acid availability. To assess the potential number and classes of hepatic genes sensitive to arginine availability at the RNA level and compare these between normal and tumor cells, we used an Affymetrix microarray approach, a paired in vitro model of normal rat hepatic cells and a tumorigenic derivative with triplicate independent replicates. Cells were exposed to arginine-deficient or control conditions for 18 hours in medium formulated to maintain differentiated function. Results Initial two-way analysis with a p-value of 0.05 identified 1419 genes in normal cells versus 2175 in tumor cells whose expression was altered in arginine-deficient conditions relative to controls, representing 9–14% of the rat genome. More stringent bioinformatic analysis with 9-way comparisons and a minimum of 2-fold variation narrowed this set to 56 arginine-responsive genes in normal liver cells and 162 in tumor cells. Approximately half the arginine-responsive genes in normal cells overlap with those in tumor cells. Of these, the majority was increased in expression and included multiple growth, survival, and stress-related genes. GADD45, TA1/LAT1, and caspases 11 and 12 were among this group. Previously known amino acid regulated genes were among the pool in both cell types. Available cDNA probes allowed independent validation of microarray data for multiple genes. Among genes downregulated under arginine-deficient conditions were multiple genes involved in cholesterol and fatty acid metabolism. Expression of low-density lipoprotein receptor was decreased in both normal and tumor cells. Conclusion Arginine-sensitive regulation appears to be an important homeostatic mechanism to coordinate cell response and nutrient availability in hepatic cells. Genes predicted as arginine-responsive in stringent microarray data analysis were confirmed by Northern blot and RT-PCR. Although the profile of arginine-responsive genes is altered and increased, a considerable portion of the "arginome" is maintained upon neoplastic transformation.
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Affiliation(s)
- Hwei Xian Leong
- Division of Hematology and Oncology, Dept. of Medicine, Rhode Island Hospital – Brown Medical School, Providence, RI, USA
| | - Carl Simkevich
- COBRE Center for Genetics and Genomics, Division of Biology and Medicine, Brown University, Providence, RI, USA
| | - Anne Lesieur-Brooks
- Division of Hematology and Oncology, Dept. of Medicine, Rhode Island Hospital – Brown Medical School, Providence, RI, USA
| | - Bonnie W Lau
- Dept. Pathology and Laboratory Medicine, Rhode Island Hospital – Brown Medical School, Providence, RI, USA
| | - Celine Fugere
- Division of Hematology and Oncology, Dept. of Medicine, Rhode Island Hospital – Brown Medical School, Providence, RI, USA
| | - Edmond Sabo
- Dept. Pathology and Laboratory Medicine, Rhode Island Hospital – Brown Medical School, Providence, RI, USA
| | - Nancy L Thompson
- Division of Hematology and Oncology, Dept. of Medicine, Rhode Island Hospital – Brown Medical School, Providence, RI, USA
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Abstract
During liver regeneration after partial hepatectomy, normally quiescent hepatocytes undergo one or two rounds of replication to restore the liver mass by a process of compensatory hyperplasia. A large number of genes are involved in liver regeneration, but the essential circuitry required for the process may be categorized into three networks: cytokine, growth factor and metabolic. There is much redundancy within each network, and intricate interactions exist between them. Thus, loss of function from a single gene rarely leads to complete blockage of liver regeneration. The innate immune system plays an important role in the initiation of liver regeneration after partial hepatectomy, and new cytokines and receptors that participate in initiation mechanisms have been identified. Hepatocytes primed by these agents readily respond to growth factors and enter the cell cycle. Presumably, the increased metabolic demands placed on hepatocytes of the regenerating liver are linked to the machinery needed for hepatocyte replication, and may function as a sensor that calibrates the regenerative response according to body demands. In contrast to the regenerative process after partial hepatectomy, which is driven by the replication of existing hepatocytes, liver repopulation after acute liver failure depends on the differentiation of progenitor cells. Such cells are also present in chronic liver diseases, but their contribution to the production of hepatocytes in those conditions is unknown. Most of the new knowledge about the molecular and cellular mechanisms of liver regeneration is both conceptually important and directly relevant to clinical problems.
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Affiliation(s)
- Nelson Fausto
- Department of Pathology, University of Washington School of Medicine, Seattle, WA 98195-7470, USA.
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Burke ZD, Shen CN, Ralphs KL, Tosh D. Characterization of liver function in transdifferentiated hepatocytes. J Cell Physiol 2005; 206:147-59. [PMID: 15965953 DOI: 10.1002/jcp.20438] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We previously demonstrated that dexamethasone (Dex) induces the transdifferentiation (or conversion) of the pancreatic progenitor cell line AR42J-B13 (B13) to hepatocytes based on the expression of liver proteins. We have extended our original observations to determine: (1) the effects of Dex on pancreatic gene expression; (2) the time course of expression of liver enriched transcription factors during conversion from pancreatic to hepatic phenotype; (3) the functional potential of transdifferentiated hepatocytes; (4) the proliferative capacity of transdifferentiated hepatocytes; and (5) whether ectopic expression of transcription factors can induce the hepatic phenotype in pancreatic B13 cells. The results were as follows. The B13 cell markers amylase, synaptophysin, and neurofilament were lost in transdifferentiated hepatocytes compared to control cells and the liver enriched transcription factors C/EBPbeta and C/EBPalpha were induced first, followed by HNF4alpha and then RXRalpha. Using RT-PCR analysis and immunolocalisation studies, we detected hepatic markers (e.g., apolipoprotein B) in Dex-treated cells. In transdifferentiated hepatocytes albumin was secreted, insulin stimulated lipid deposition and ciprofibrate enhanced the expression of catalase. Proliferation of transdifferentiated hepatocytes is promoted in the presence of HGF and NEAA as indicated by the co-expression of the cell cycle markers cyclin D and phosphohistone H3 with liver proteins. Lastly, ectopic expression of C/EBPalpha or C/EBPbeta in AR42J-B13 cells was sufficient to induce transdifferentiation, based on nuclear localization of HNF4alpha and induction of UDP-glucuronosyltransferase expression. These results indicate that the B13 progenitor cell model is suitable for studying liver function and for understanding the molecular and cellular events that occur during transdifferentiation.
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Affiliation(s)
- Zoë D Burke
- Centre for Regenerative Medicine, Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
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Pallet N, Thervet E, Le Corre D, Knebelmann B, Nusbaum P, Tomkiewicz C, Meria P, Flinois JP, Beaune P, Legendre C, Anglicheau D. Rapamycin inhibits human renal epithelial cell proliferation: Effect on cyclin D3 mRNA expression and stability. Kidney Int 2005; 67:2422-33. [PMID: 15882288 DOI: 10.1111/j.1523-1755.2005.00350.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Recent data have suggested that rapamycin use during the initial period after transplantation is associated with prolonged delayed graft function (DGF). Because of the known effects of rapamycin in other cell types, we speculated that this action may be secondary to human renal epithelial cells (HRECs) inhibition of proliferation. METHODS Primary cultures of HRECs were incubated with various concentrations of rapamycin. Cell proliferation was evaluated by cytotoxicity assays. The cell cycle was analyzed by flow cytometry. Protein expression levels were assessed by Western blot. Cyclin D3 mRNA levels were measured by quantitative real-time polymerase chain reaction (PCR). The transcriptional activity of the cyclin D3 gene was evaluated using transient transfection. RESULTS Rapamycin exerted a significant concentration-dependent antiproliferative effect on growing HRECs by inhibiting the G(1) to S transition. The p70(S6) kinase pathway leading to cell cycle progression was found to be active, and low concentrations of rapamycin dramatically reduced p70(S6) kinase phosphorylation. Rapamycin completely inhibited the increase in cyclin D3 protein expression and mRNA accumulation induced by fetal calf serum, but did not affect cyclin E or cdk-inhibitor expression levels. This regulation of cyclin D3 protein expression is mainly due to a destabilization of its mRNA. Rapamycin reduced the mRNA half-life by 26% (4.8 +/- 1.3 hours vs. 6.5 +/- 1.0 hours, P < 0.001). CONCLUSION Rapamycin inhibits the proliferative response of HRECs to mitogenic stimuli, and causes cell cycle arrest in the early G(1) phase, not only by a nonspecific process due to inhibition of the p70(S6k) pathway, but also by a direct effect on cyclin D3 mRNA stability.
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Affiliation(s)
- Nicolas Pallet
- Unité INSERM UMR S490, Molecular Toxicology, Centre Universitaire des Saints-Pères, Université René Descartes, Paris, France
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35
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Abstract
Cyclin D1 encodes the regulatory subunit of a holoenzyme that phosphorylates and inactivates the retinoblastoma protein and promotes progression through the G1-S phase of the cell cycle. Amplification or overexpression of cyclin D1 plays pivotal roles in the development of a subset of human cancers including parathyroid adenoma, breast cancer, colon cancer, lymphoma, melanoma, and prostate cancer. Of the three D-type cyclins, each of which binds cyclin-dependent kinase (CDK), it is cyclin D1 overexpression that is predominantly associated with human tumorigenesis and cellular metastases. In recent years accumulating evidence suggests that in addition to its original description as a CDK-dependent regulator of the cell cycle, cyclin D1 also conveys cell cycle or CDK-independent functions. Cyclin D1 associates with, and regulates activity of, transcription factors, coactivators and corepressors that govern histone acetylation and chromatin remodeling proteins. The recent findings that cyclin D1 regulates cellular metabolism, fat cell differentiation and cellular migration have refocused attention on novel functions of cyclin D1 and their possible role in tumorigenesis. In this review, both the classic and novel functions of cyclin D1 are discussed with emphasis on the CDK-independent functions of cyclin D1.
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Affiliation(s)
- Maofu Fu
- Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, Washington, DC 20057-1468, USA
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36
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Nelsen CJ, Kuriyama R, Hirsch B, Negron VC, Lingle WL, Goggin MM, Stanley MW, Albrecht JH. Short term cyclin D1 overexpression induces centrosome amplification, mitotic spindle abnormalities, and aneuploidy. J Biol Chem 2004; 280:768-76. [PMID: 15509582 DOI: 10.1074/jbc.m407105200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In normal cells, cyclin D1 is induced by growth factors and promotes progression through the G(1) phase of the cell cycle. Cyclin D1 is also an oncogene that is thought to act primarily by bypassing the requirement for mitogens during the G(1) phase. Studies of clinical tumors have found that cyclin D1 overexpression is associated with chromosome abnormalities, although a causal effect has not been established in experimental systems. In this study, we found that transient expression of cyclin D1 in normal hepatocytes in vivo triggered dysplastic mitoses, accumulation of supernumerary centrosomes, abnormalities of the mitotic spindle, and marked chromosome changes within several days. This was associated with up-regulation of checkpoint genes p53 and p21 as well as hepatocyte apoptosis in the liver. Transient transfection of cyclin D1 also induced centrosome and mitotic spindle abnormalities in breast epithelial cells, suggesting that this may be a generalized effect. These results indicate that cyclin D1 can induce deregulation of the mitotic apparatus and aneuploidy, effects that could contribute to the role of this oncogene in malignancy.
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Affiliation(s)
- Christopher J Nelsen
- Division of Gastroenterology, Hennepin County Medical Center, Minneapolis, Minnesota 55415, USA
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Pennisi PA, Kopchick JJ, Thorgeirsson S, LeRoith D, Yakar S. Role of growth hormone (GH) in liver regeneration. Endocrinology 2004; 145:4748-55. [PMID: 15242989 DOI: 10.1210/en.2004-0655] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Liver regeneration is a fundamental mechanism by which the liver responds to injury. This process is regulated by endogenous growth factors and cytokines, and it involves proliferation of all mature cells that exist within the intact organ. To understand the role of the GH/IGF-I axis in liver regeneration, we performed partial hepatectomies in three groups of mice: GH antagonist (GHa) transgenic mice, in which the action of GH is blocked; liver IGF-I-deficient mice that lack IGF-I specifically in the liver and also lack the acid-labile subunit (ALS; LID+ALSKO mice), in which IGF-I levels are very low and GH secretion is increased; and control mice. Interestingly, the survival rate of GHa transgenic mice was dramatically reduced after partial hepatectomy (57%) compared with the survival rate of controls (100%) or LID+ALSKO mice (88%). In control mice, the liver was completely regenerated after 4 d, whereas liver regeneration required 7 d in LID+ALSKO mice. In contrast, in GHa mice, liver regeneration reached only 70% of the original liver mass after 4 d and did not improve thereafter. Strikingly, 36 and 48 h after hepatectomy, the livers of control and LID+ALSKO mice, respectively, exhibited intense 5-bromo-2'-deoxyuridine (BrdU) staining, whereas BrdU staining was dramatically decreased in the livers of GHa-treated mice. These results suggest that GH plays a critical role in liver regeneration, although whether it acts directly or indirectly remains to be determined.
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Affiliation(s)
- Patricia A Pennisi
- Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Room 8D12, Building 10, National Institutes of Health, Bethesda, Maryland 20892-1758, USA
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Goggin MM, Nelsen CJ, Kimball SR, Jefferson LS, Morley SJ, Albrecht JH. Rapamycin-sensitive induction of eukaryotic initiation factor 4F in regenerating mouse liver. Hepatology 2004; 40:537-44. [PMID: 15349891 DOI: 10.1002/hep.20338] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Following acute injuries that diminish functional liver mass, the remaining hepatocytes substantially increase overall protein synthesis to meet increased metabolic demands and to allow for compensatory liver growth. Previous studies have not clearly defined the mechanisms that promote protein synthesis in the regenerating liver. In the current study, we examined the regulation of key proteins involved in translation initiation following 70% partial hepatectomy (PH) in mice. PH promoted the assembly of eukaryotic initiation factor (eIF) 4F complexes consisting of eIF4E, eIF4G, eIF4A1, and poly-A binding protein. eIF4F complex formation after PH occurred without detectable changes in eIF4E-binding protein 1 (4E-BP1) phosphorylation or its binding eIF4E. The amount of serine 1108-phosphorylated eIF4G (but not Ser209-phosphorylated eIF4E) was induced following PH. These effects were antagonized by treatment with rapamycin, indicating that target of rapamycin (TOR) activity is required for eIF4F assembly in the regenerating liver. Rapamycin inhibited the induction of cyclin D1, a known eIF4F-sensitive gene, at the level of protein expression but not messenger RNA (mRNA) expression. In conclusion, increased translation initiation mediated by the mRNA cap-binding complex eIF4F contributes to the induction of protein synthesis during compensatory liver growth. Further study of factors that regulate translation initiation may provide insight into mechanisms that govern metabolic homeostasis and regeneration in response to liver injury.
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Affiliation(s)
- Melissa M Goggin
- Division of Gastroenterology, Hennepin County Medical Center, Minneapolis, MN 55415, USA
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Tomiya T, Inoue Y, Yanase M, Arai M, Ikeda H, Tejima K, Nagashima K, Nishikawa T, Watanabe N, Omata M, Fujiwara K. Treatment with leucine stimulates the production of hepatocyte growth factor in vivo. Biochem Biophys Res Commun 2004; 322:772-7. [PMID: 15336531 DOI: 10.1016/j.bbrc.2004.07.191] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2004] [Indexed: 01/08/2023]
Abstract
Hepatocyte growth factor (HGF) has pleiotropic effects. Up-regulation of HGF activity in vivo may be beneficial. Branched-chain amino acids (BCAAs) are known to modulate various cellular functions. When starved rats received intraperitoneal injections of valine, leucine or isoleucine, only leucine treatment increased both hepatic and circulating levels of HGF in a dose-dependent manner, up to 1.5 and 2.3 times higher, respectively, than in controls. When young growing rats with free access to food were injected with leucine once a day for a week, HGF levels and liver weights were significantly higher than those of control rats. Furthermore, 1 week of leucine treatment of adult rats resulted in elevated serum albumin levels with an increase in HGF levels. Taken together with our previous report showing that leucine stimulates HGF production by hepatic stellate cells in culture, leucine, among BCAAs, may induce an increase in HGF production by the liver in vivo.
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Affiliation(s)
- Tomoaki Tomiya
- Department of Gastroenterology, University of Tokyo, Tokyo, Japan.
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40
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Abstract
Growth of organisms and their constituent parts responds to both intrinsic and extrinsic cues during development: organisms of a given species generally grow at a predictable rate and to a specific body size, but individuals can modify this program during development in response to environmental conditions. Recent experiments, using gene knockouts and targeted overexpression, have revealed the central role of a signaling network controlled by the PI3K and TOR kinases in this regulation. These signaling molecules control growth by coordinately regulating a large number of cell biological processes. This review focuses on the cellular activities regulated by PI3K and TOR during development, and discusses how changes in different aspects of cellular metabolism may interact to regulate growth.
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Affiliation(s)
- Thomas P Neufeld
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA.
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Leung-Pineda V, Pan Y, Chen H, Kilberg MS. Induction of p21 and p27 expression by amino acid deprivation of HepG2 human hepatoma cells involves mRNA stabilization. Biochem J 2004; 379:79-88. [PMID: 14715082 PMCID: PMC1224060 DOI: 10.1042/bj20031383] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2003] [Accepted: 01/12/2004] [Indexed: 01/12/2023]
Abstract
mRNA abundance for a number of genes is increased by amino acid limitation. From an array screening study in HepG2 human hepatoma cells, it was established that one set of genes affected by amino acid availability is the set associated with cell-cycle control. The present study describes the increased expression of both mRNA and protein for the cyclin-dependent kinase inhibitors p21 and p27 in response to deprivation of HepG2 cells for a single essential amino acid, histidine. The increase in p21 and p27 mRNA content depended on de novo protein synthesis and involved a post-transcriptional mRNA stabilization component. For p21, increase in mRNA by histidine depletion appeared to be independent of p53 transactivation, and the absolute level of p53 protein was unaffected by this treatment. Histidine limitation caused an increase in the phosphorylation of ERK1/ERK2 (extracellular-signal-regulated kinase), and inhibition of the ERK signal transduction pathway resulted in a reduction in the starvation-dependent increase in p21 mRNA. Blockade of the phosphoinositide 3-kinase and mTOR (mammalian target of rapamycin) pathways also blunted the increase in p21 mRNA content. These results document the amino acid-dependent control of the synthesis of specific cell-cycle regulators and help to explain the block at G1 phase after amino acid limitation.
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MESH Headings
- Amino Acids/deficiency
- Amino Acids/physiology
- Carcinoma, Hepatocellular/metabolism
- Carcinoma, Hepatocellular/pathology
- Cell Cycle Proteins/biosynthesis
- Cell Cycle Proteins/genetics
- Cell Line, Tumor/metabolism
- Cyclin-Dependent Kinase Inhibitor p21
- Cyclin-Dependent Kinase Inhibitor p27
- Cyclins/biosynthesis
- Cyclins/genetics
- Enzyme Inhibitors/pharmacology
- G1 Phase/drug effects
- Gene Expression Regulation, Neoplastic/genetics
- Genes, Reporter
- Genes, cdc
- Humans
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases/metabolism
- Nucleic Acid Synthesis Inhibitors/pharmacology
- Phosphatidylinositol 3-Kinases/physiology
- Phosphoinositide-3 Kinase Inhibitors
- Promoter Regions, Genetic
- Protein Deficiency/metabolism
- Protein Kinase Inhibitors
- Protein Kinases/physiology
- Protein Synthesis Inhibitors/pharmacology
- RNA Processing, Post-Transcriptional
- RNA, Messenger/metabolism
- RNA, Neoplasm/metabolism
- Signal Transduction
- TOR Serine-Threonine Kinases
- Tumor Suppressor Proteins/biosynthesis
- Tumor Suppressor Proteins/genetics
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Affiliation(s)
- Van Leung-Pineda
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Box 100245, JHMHC, Gainesville, FL 32610-0245, USA
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Radaeva S, Sun R, Pan HN, Hong F, Gao B. Interleukin 22 (IL-22) plays a protective role in T cell-mediated murine hepatitis: IL-22 is a survival factor for hepatocytes via STAT3 activation. Hepatology 2004; 39:1332-42. [PMID: 15122762 DOI: 10.1002/hep.20184] [Citation(s) in RCA: 480] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The central role of T cell activation in hepatocellular injury has been well documented. In this article, we provide evidence suggesting that T cells may also play a protective role in liver disease by releasing interleukin-22 (IL-22), a recently identified T cell-derived cytokine whose biological significance is unclear. IL-22 messenger RNA and protein expression are significantly elevated in T cell-mediated hepatitis induced by concanavalin A (ConA) but are less extensively elevated in the carbon tetrachloride-induced liver injury model. Activated CD3(+) T cells are likely responsible for the production of IL-22 in the liver after injection of ConA. The IL-22 receptor is normally expressed at high levels by hepatocytes and further induced after ConA injection. IL-22 blockade with a neutralizing antibody reduces signal transducer and activator of transcription factor 3 (STAT3) activation and worsens liver injury in T cell-mediated hepatitis, whereas injection of recombinant IL-22 attenuates such injury. In vitro treatment with recombinant IL-22 or overexpression of IL-22 promotes cell growth and survival in human hepatocellular carcinoma HepG2 cells. Stable overexpression of IL-22 in HepG2 cells constitutively activates STAT3 and induces expression of a variety of antiapoptotic (e.g., Bcl-2, Bcl-xL, Mcl-1) and mitogenic (e.g., c-myc, cyclin D1, Rb2, CDK4) proteins. Blocking STAT3 activation abolishes the antiapoptotic and mitogenic actions of IL-22 in hepatic cells. In conclusion, the T cell-derived cytokine IL-22 is a survival factor for hepatocytes; this suggests that T cell activation may also prevent and repair liver injury by releasing hepatoprotective cytokine IL-22 in addition to its previously documented central role in hepatocellular injury.
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Affiliation(s)
- Svetlana Radaeva
- Section on Liver Biology, Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
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