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Nakano Y, Saijou E, Itoh T, Tanaka M, Miyajima A, Kido T. Development of a high throughput system to screen compounds that revert the activated hepatic stellate cells to a quiescent-like state. Sci Rep 2024; 14:8536. [PMID: 38609454 PMCID: PMC11014936 DOI: 10.1038/s41598-024-58989-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 04/05/2024] [Indexed: 04/14/2024] Open
Abstract
Chronic liver injury induces fibrosis that often proceeds to cirrhosis and hepatocellular carcinoma, indicating that prevention and/or resolution of fibrosis is a promising therapeutic target. Hepatic stellate cells (HSCs) are the major driver of fibrosis by expressing extracellular matrices (ECM). HSCs, in the normal liver, are quiescent and activated by liver injury to become myofibroblasts that proliferate and produce ECM. It has been shown that activated HSCs (aHSCs) become a "quiescent-like" state by removal of liver insults. Therefore, deactivation agents can be a therapeutic drug for advanced liver fibrosis. Using aHSCs prepared from human induced pluripotent stem cells, we found that aHSCs were reverted to a quiescent-like state by a combination of chemical compounds that either inhibit or activate a signaling pathway, Lanifibranor, SB431542, Dorsomorphin, retinoic acid, palmitic acid and Y27632, in vitro. Based on these results, we established a high throughput system to screen agents that induce deactivation and demonstrate that a single chemical compound can induce deactivation.
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Affiliation(s)
- Yasuhiro Nakano
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo, 113-0032, Japan
- Division of Cancer and Senescence Biology, Cancer Research Institute, and Institute for Frontier Science Initiative, Kanazawa University, Kakuma, Kanazawa, 920-1192, Japan
| | - Eiko Saijou
- Laboratory of Computational Genomics, Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-Ku, Tokyo, 113-0032, Japan
| | - Tohru Itoh
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo, 113-0032, Japan
- Research Core, Institute of Research, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-Ku, Tokyo, 113-8510, Japan
| | - Minoru Tanaka
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-Ku, Tokyo, 162-8655, Japan
- Laboratory of Stem Cell Regulation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo, Tokyo, 113-0032, Japan
| | - Atsushi Miyajima
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo, 113-0032, Japan
| | - Taketomo Kido
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo, 113-0032, Japan.
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Koui Y, Himeno M, Mori Y, Nakano Y, Saijou E, Tanimizu N, Kamiya Y, Anzai H, Maeda N, Wang L, Yamada T, Sakai Y, Nakato R, Miyajima A, Kido T. Development of human iPSC-derived quiescent hepatic stellate cell-like cells for drug discovery and in vitro disease modeling. Stem Cell Reports 2021; 16:3050-3063. [PMID: 34861166 PMCID: PMC8693663 DOI: 10.1016/j.stemcr.2021.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 11/01/2021] [Accepted: 11/02/2021] [Indexed: 02/07/2023] Open
Abstract
Hepatic stellate cells (HSCs) play a central role in the progression of liver fibrosis by producing extracellular matrices. The development of drugs to suppress liver fibrosis has been hampered by the lack of human quiescent HSCs (qHSCs) and an appropriate in vitro model that faithfully recapitulates HSC activation. In the present study, we developed a culture system to generate qHSC-like cells from human-induced pluripotent stem cells (hiPSCs) that can be converted into activated HSCs in culture. To monitor the activation process, a red fluorescent protein (RFP) gene was inserted in hiPSCs downstream of the activation marker gene actin alpha 2 smooth muscle (ACTA2). Using qHSC-like cells derived from RFP reporter iPSCs, we screened a repurposing chemical library and identified therapeutic candidates that prevent liver fibrosis. Hence, hiPSC-derived qHSC-like cells will be a useful tool to study the mechanism of HSC activation and to identify therapeutic agents.
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Affiliation(s)
- Yuta Koui
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Misao Himeno
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yusuke Mori
- Bio Science & Engineering Laboratory, Research & Development Management Headquarters, FUJIFILM Corporation, 577 Ushijima, Kaisei-machi, Ashigarakami-gun, Kanagawa 258-8577, Japan
| | - Yasuhiro Nakano
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Eiko Saijou
- Laboratory of Computational Genomics, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Naoki Tanimizu
- Department of Tissue Development and Regeneration, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, S-1, W-17, Chuo-ku, Sapporo 060-8556, Japan
| | - Yoshiko Kamiya
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Hiroko Anzai
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Natsuki Maeda
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Luyao Wang
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Tadanori Yamada
- Bio Science & Engineering Laboratory, Research & Development Management Headquarters, FUJIFILM Corporation, 577 Ushijima, Kaisei-machi, Ashigarakami-gun, Kanagawa 258-8577, Japan
| | - Yasuyuki Sakai
- Department of Chemical System Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Ryuichiro Nakato
- Laboratory of Computational Genomics, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Atsushi Miyajima
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Taketomo Kido
- Laboratory of Cell Growth and Differentiation, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
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Saijou E, Enomoto Y, Matsuda M, Yuet‐Yin Kok C, Akira S, Tanaka M, Miyajima A. Neutrophils alleviate fibrosis in the CCl 4-induced mouse chronic liver injury model. Hepatol Commun 2018; 2:703-717. [PMID: 29881822 PMCID: PMC5983199 DOI: 10.1002/hep4.1178] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 02/26/2018] [Accepted: 03/01/2018] [Indexed: 12/25/2022] Open
Abstract
Tribbles pseudokinase 1 (Trib1) is a negative regulator of CCAAT/enhancer binding protein α (C/EBPα) and is known to induce granulopoiesis while suppressing monocyte differentiation. Loss of Trib1 was previously shown to increase the neutrophil population in the spleen but lead to M2-like macrophage reduction. Because M2 macrophages are anti-inflammatory and promote tissue repair by producing fibrogenic factors, we investigated liver fibrosis in Trib1-deficient mice. Interestingly, loss of Trib1 suppressed fibrosis in the CCl4-induced chronic liver injury model. Trib1 knockout increased neutrophils but had a minimal effect on the macrophage population in the liver. Hepatic expressions of neutrophil matrix metalloproteinases (Mmp)8 and Mmp9 were increased, but the production of fibrogenic factors, including transforming growth factor β1, was not affected by loss of Trib1. These results suggest that neutrophils are responsible for the suppression of fibrosis in Trib1-deficient liver. Consistently, transplantation of Trib1-deficient bone marrow cells into wild-type mice alleviated CCl4-induced fibrosis. Furthermore, expression of chemokine (C-X-C motif) ligand 1 (Cxcl1) by adeno-associated viral vector in the normal liver recruited neutrophils and suppressed CCl4-induced fibrosis; infusion of wild-type neutrophils in CCl4-treated mice also ameliorated fibrosis. Using recombinant adeno-associated virus-mediated expression of Mmp8 and Mmp9 alleviated liver fibrosis. Finally, neutrophil depletion by infusion of Ly6G antibody significantly enhanced CCl4-induced fibrosis. Conclusion: While neutrophils are well known to exacerbate acute liver injury, our results demonstrate a beneficial role of neutrophils in chronic liver injury by promoting fibrolysis. (Hepatology Communications 2018;2:703-717).
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Affiliation(s)
- Eiko Saijou
- Institute of Molecular and Cellular BiosciencesUniversity of TokyoTokyoJapan
| | - Yutaka Enomoto
- Institute of Molecular and Cellular BiosciencesUniversity of TokyoTokyoJapan
| | - Michitaka Matsuda
- Institute of Molecular and Cellular BiosciencesUniversity of TokyoTokyoJapan
- Research InstituteNational Center for Global Health and MedicineTokyoJapan
| | - Cindy Yuet‐Yin Kok
- Institute of Molecular and Cellular BiosciencesUniversity of TokyoTokyoJapan
- Research InstituteNational Center for Global Health and MedicineTokyoJapan
| | - Shizuo Akira
- Immunology Frontier Research CenterOsaka UniversitySuitaJapan
| | - Minoru Tanaka
- Institute of Molecular and Cellular BiosciencesUniversity of TokyoTokyoJapan
- Research InstituteNational Center for Global Health and MedicineTokyoJapan
| | - Atsushi Miyajima
- Institute of Molecular and Cellular BiosciencesUniversity of TokyoTokyoJapan
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Matsuda M, Tsurusaki S, Miyata N, Saijou E, Okochi H, Miyajima A, Tanaka M. Oncostatin M causes liver fibrosis by regulating cooperation between hepatic stellate cells and macrophages in mice. Hepatology 2018; 67:296-312. [PMID: 28779552 DOI: 10.1002/hep.29421] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 07/21/2017] [Accepted: 08/02/2017] [Indexed: 12/26/2022]
Abstract
UNLABELLED Fibrosis is an important wound-healing process in injured tissues, but excessive fibrosis is often observed in patients with chronic inflammation. Although oncostatin M (OSM) has been reported to play crucial roles for recovery from acute liver injury by inducing tissue inhibitor of metalloproteinase 1 (Timp1) expression, the role of OSM in chronic liver injury (CLI) is yet to be elucidated. Here, we show that OSM exerts powerful fibrogenic activity by regulating macrophage activation during CLI. Genetic ablation of the OSM gene alleviated fibrosis in a mouse model of chronic hepatitis. Conversely, continuous expression of OSM in a normal mouse liver by hydrodynamic tail vein injection (HTVi) induced severe fibrosis without necrotic damage of hepatocytes, indicating that OSM is involved in the fundamental process of liver fibrosis (LF) after hepatitis. In a primary coculture of hepatic stellate cells (HSCs) and hepatic macrophages (HMs), OSM up-regulated the expression of fibrogenic factors, such as transforming growth factor-β and platelet-derived growth factor in HMs, while inducing Timp1 expression in HSCs, suggesting the synergistic roles of OSM for collagen deposition in the liver. Fluorescence-activated cell sorting analyses using OSM-HTVi and OSM knockout mice have revealed that bone-marrow-derived monocyte/macrophage are responsive to OSM for profibrotic activation. Furthermore, depletion or blocking of HMs by administration of clodronate liposome or chemokine inhibitor prevented OSM-induced fibrosis. CONCLUSION OSM plays a crucial role in LF by coordinating the phenotypic change of HMs and HSCs. Our data suggest that OSM is a promising therapeutic target for LF. (Hepatology 2018;67:296-312).
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Affiliation(s)
- Michitaka Matsuda
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Shinya Tsurusaki
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.,Laboratory of Stem Cell Regulation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Naoko Miyata
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Eiko Saijou
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Hitoshi Okochi
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Atsushi Miyajima
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Minoru Tanaka
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.,Laboratory of Stem Cell Regulation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
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Yagai T, Matsui S, Harada K, Inagaki FF, Saijou E, Miura Y, Nakanuma Y, Miyajima A, Tanaka M. Expression and localization of sterile alpha motif domain containing 5 is associated with cell type and malignancy of biliary tree. PLoS One 2017; 12:e0175355. [PMID: 28388653 PMCID: PMC5384680 DOI: 10.1371/journal.pone.0175355] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 03/07/2017] [Indexed: 12/15/2022] Open
Abstract
Cholangiocarcinoma (CC) is a type of relatively rare neoplasm in adenocarcinoma. The characteristics of CCs as well as biliary epithelial cells are heterogeneous at the different portion of the biliary tree. There are two candidate stem/progenitor cells of the biliary tree, i.e., biliary tree stem/progenitor cell (BTSC) at the peribiliary gland (PBG) of large bile ducts and liver stem/progenitor cell (LPC) at the canals of Hering of peripheral small bile duct. Although previous reports suggest that intrahepatic CC (ICC) can arise from such stem/progenitor cells, the characteristic difference between BTSC and LPC in pathological process needs further investigation, and the etiology of CC remains poorly understood. Here we show that Sterile alpha motif domain containing 5 (SAMD5) is exclusively expressed in PBGs of large bile ducts in normal mice. Using a mouse model of cholestatic liver disease, we demonstrated that SAMD5 expression was upregulated in the large bile duct at the hepatic hilum, the extrahepatic bile duct and PBGs, but not in proliferating intrahepatic ductules, suggesting that SAMD5 is expressed in BTSC but not LPC. Intriguingly, human ICCs and extrahepatic CCs exhibited striking nuclear localization of SAMD5 while the normal hilar large bile duct displayed slight-to-moderate expression in cytoplasm. In vitro experiments using siRNA for SAMD5 revealed that SAMD5 expression was associated with the cell cycle regulation of CC cell lines. Conclusion: SAMD5 is a novel marker for PBG but not LPC in mice. In humans, the expression and location of SAMD5 could become a promising diagnostic marker for the cell type as well as malignancy of bile ducts and CCs.
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Affiliation(s)
- Tomoki Yagai
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Satoshi Matsui
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Kenichi Harada
- Department of Human Pathology, Kanazawa University Graduate School of Medicine, Kanazawa, Japan
| | - Fuyuki F. Inagaki
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Eiko Saijou
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Yasushi Miura
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
- Department of Life Science and Medical Bio-Science, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Yasuni Nakanuma
- Department of Human Pathology, Kanazawa University Graduate School of Medicine, Kanazawa, Japan
| | - Atsushi Miyajima
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
| | - Minoru Tanaka
- Department of Regenerative Medicine, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
- Laboratory of Stem Cell Regulation, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
- * E-mail:
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Hirose Y, Saijou E, Sugano Y, Takeshita F, Nishimura S, Nonaka H, Chen YR, Sekine K, Kido T, Nakamura T, Kato S, Kanke T, Nakamura K, Nagai R, Ochiya T, Miyajima A. Inhibition of Stabilin-2 elevates circulating hyaluronic acid levels and prevents tumor metastasis. Proc Natl Acad Sci U S A 2012; 109:4263-8. [PMID: 22371575 PMCID: PMC3306694 DOI: 10.1073/pnas.1117560109] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hyaluronic acid (HA) has been implicated in the proliferation and metastasis of tumor cells. However, most previous studies were conducted on extracellular matrix or pericellular HA, and the role of circulating HA in vivo has not been studied. HA is rapidly cleared from the bloodstream. The scavenger receptor Stabilin-2 (Stab2) is considered a major clearance receptor for HA. Here we report a dramatic elevation in circulating HA levels in Stab2-deficient mice without any overt phenotype. Surprisingly, the metastasis of B16F10 melanoma cells to the lungs was markedly suppressed in the Stab2-deficient mice, whereas cell proliferation was not affected. Furthermore, administration of an anti-Stab2 antibody in Stab2(+) mice elevated serum HA levels and prevented the metastasis of melanoma to the lung, and also suppressed spontaneous metastasis of mammary tumor and human breast tumor cells inoculated in the mammary gland. Administration of the antibody or high-dose HA in mice blocked the lodging of melanoma cells to the lungs. Furthermore, HA at high concentrations inhibited the rolling/tethering of B16 cells to lung endothelial cells. These results suggest that blocking Stab2 function prevents tumor metastasis by elevating circulating HA levels. Stab2 may be a potential target in antitumor therapy.
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Affiliation(s)
| | - Eiko Saijou
- Laboratory of Cell Growth and Differentiation and
| | | | - Fumitaka Takeshita
- Division of Molecular and Cellular Medicine, National Cancer Center Research Institute, Tokyo 104-0045, Japan
| | - Satoshi Nishimura
- Department of Cardiovascular Medicine
- Translational Systems Biology and Medicine Initiative, and
| | | | | | | | | | - Takashi Nakamura
- Laboratory of Nuclear Signaling, Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 113-0032, Japan
| | - Shigeaki Kato
- Laboratory of Nuclear Signaling, Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 113-0032, Japan
| | | | | | - Ryozo Nagai
- Department of Cardiovascular Medicine
- Translational Systems Biology and Medicine Initiative, and
- Global Center of Excellence Program, Comprehensive Center of Education and Research for Chemical Biology of the Diseases, University of Tokyo, Tokyo 113-8655, Japan; and
| | - Takahiro Ochiya
- Division of Molecular and Cellular Medicine, National Cancer Center Research Institute, Tokyo 104-0045, Japan
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Saijou E, Itoh T, Kim KW, Iemura SI, Natsume T, Miyajima A. Nucleocytoplasmic Shuttling of the Zinc Finger Protein EZI Is Mediated by Importin-7-dependent Nuclear Import and CRM1-independent Export Mechanisms. J Biol Chem 2007; 282:32327-37. [PMID: 17848547 DOI: 10.1074/jbc.m706793200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Nucleocytoplasmic translocation constitutes a foundation for nuclear proteins to exert their proper functions and hence for various biological reactions to occur normally in eukaryotic cells. We reported previously that EZI/Zfp467, a 12 zinc finger motif-containing protein, localizes predominantly in the nucleus, yet the underlying mechanism still remains elusive. Here we constructed a series of mutant forms of EZI and examined their subcellular localization. The results delineated a non-canonical nuclear localization signal in the region covering the 9th to the 12th zinc fingers, which was necessary for nuclear accumulation of EZI as well as sufficient to confer nuclear localizing ability to a heterologous protein. We also found that the N-terminal domain of EZI is necessary for its nuclear export, the process of which was not sensitive to the CRM1 inhibitor leptomycin B. An interaction proteomics approach and the following co-immunoprecipitation experiments identified the nuclear import receptor importin-7 as a molecule that associated with EZI and, importantly, short interfering RNA-mediated knockdown of importin-7 expression completely abrogated nuclear accumulation of EZI. Taken together, these results identify EZI as a novel cargo protein for importin-7 and demonstrate a nucleocytoplasmic shuttling mechanism that is mediated by importin-7-dependent nuclear localization and CRM1-independent nuclear export.
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Affiliation(s)
- Eiko Saijou
- Laboratory of Cell Growth and Differentiation, Institute of Molecular and Cellular Biosciences, the University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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Naiki T, Saijou E, Miyaoka Y, Sekine K, Miyajima A. TRB2, a mouse Tribbles ortholog, suppresses adipocyte differentiation by inhibiting AKT and C/EBPbeta. J Biol Chem 2007; 282:24075-82. [PMID: 17576771 DOI: 10.1074/jbc.m701409200] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Adipocyte differentiation is regulated by a complex array of extracellular signals, intracellular mediators and transcription factors. Here we describe suppression of adipocyte differentiation by TRBs, mammalian orthologs of Drosophila Tribbles. Whereas all the three TRBs were expressed in 3T3-L1 preadipocytes, TRB2 and TRB3, but not TRB1, were immediately down-regulated by differentiation stimuli. Forced expression of TRB2 and TRB3 inhibited adipocyte differentiation at an early stage. Akt activation is a key event in adipogenesis and was severely inhibited by TRB3 in 3T3-L1 cells. However, the inhibition by TRB2 was mild compared with severe inhibition by TRB3, though TRB2 suppressed adipogenesis as strongly as TRB3. Interestingly, TRB2 but not TRB3 reduced the level of C/EBPbeta, a transcription factor required for an early stage of adipogenesis, through a proteasome-dependent mechanism. Furthermore, knockdown of endogenous TRB2 by siRNA allowed 3T3-L1 cells to differentiate without full differentiation stimuli. These results suggest that inhibition of Akt activation in combination with degradation of C/EBPbeta is the basis for the strong inhibitory effect of TRB2 on adipogenesis.
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Affiliation(s)
- Takahiro Naiki
- Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Tokyo 113-0032, Japan
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Saijou E, Fujiwara T, Suzaki T, Inoue K, Sakamoto H. RBD-1, a nucleolar RNA-binding protein, is essential for Caenorhabditis elegans early development through 18S ribosomal RNA processing. Nucleic Acids Res 2004; 32:1028-36. [PMID: 14872060 PMCID: PMC373399 DOI: 10.1093/nar/gkh264] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
RBD-1 is the Caenorhabditis elegans homolog of Mrd1p, which was recently shown to be required for 18S ribosomal RNA (rRNA) processing in yeast. To gain insights into the relationship between ribosome biogenesis and the development of multicellular organisms, we examined the expression and function of RBD-1. Maternal RBD-1 in the fertilized egg disappears immediately after cleavage starts, whereas zygotic RBD-1 first appears in late embryos and is localized in the nucleolus in most cells, although zygotic transcription of pre-rRNA is known to be initiated as early as the one-cell stage. RNA interference of the rbd-1 gene severely inhibits the processing of 18S rRNA in association with various developmental abnormalities, indicating its essential role in pre-rRNA processing and development in C.elegans. These results provide evidence for the linkage between ribosome biogenesis and the control of development and imply unexpected uncoupling of transcription and processing of pre-rRNA in early C.elegans embryos.
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Affiliation(s)
- Eiko Saijou
- Department of Biology, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodaicho, Nadaku, Kobe 657-8501, Japan
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