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Pörschke M, Rodríguez-González I, Parfentev I, Urlaub H, Kehlenbach RH. Transportin 1 is a major nuclear import receptor of the nitric oxide synthase interacting protein. J Biol Chem 2023; 299:102932. [PMID: 36690276 PMCID: PMC9974451 DOI: 10.1016/j.jbc.2023.102932] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 01/12/2023] [Accepted: 01/14/2023] [Indexed: 01/22/2023] Open
Abstract
The nitric oxide synthase interacting protein (NOSIP), an E3-ubiquitin ligase, is involved in various processes like neuronal development, craniofacial development, granulopoiesis, mitogenic signaling, apoptosis, and cell proliferation. The best-characterized function of NOSIP is the regulation of endothelial nitric oxide synthase activity by translocating the membrane-bound enzyme to the cytoskeleton, specifically in the G2 phase of the cell cycle. For this, NOSIP itself has to be translocated from its prominent localization, the nucleus, to the cytoplasm. Nuclear import of NOSIP was suggested to be mediated by the canonical transport receptors importin α/β. Recently, we found NOSIP in a proteomic screen as a potential importin 13 cargo. Here, we describe the nuclear shuttling characteristics of NOSIP in living cells and in vitro and show that it does not interact directly with importin α. Instead, it formed stable complexes with several importins (-β, -7, -β/7, -13, and transportin 1) and was also imported into the nucleus in digitonin-permeabilized cells by these factors. In living HeLa cells, transportin 1 seems to be the major nuclear import receptor for NOSIP. A detailed analysis of the NOSIP-transportin 1 interaction revealed a high affinity and an unusual binding mode, involving the N-terminal half of transportin 1. In contrast to nuclear import, nuclear export of NOSIP seems to occur mostly by passive diffusion. Thus, our results uncover additional layers in the larger process of endothelial nitric oxide synthase regulation.
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Affiliation(s)
- Marius Pörschke
- Department of Molecular Biology, Faculty of Medicine, GZMB, Georg-August-University Göttingen, Göttingen, Germany
| | - Inés Rodríguez-González
- Department of Molecular Biology, Faculty of Medicine, GZMB, Georg-August-University Göttingen, Göttingen, Germany
| | - Iwan Parfentev
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany,Bioanalytics Group, Institute of Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Ralph H. Kehlenbach
- Department of Molecular Biology, Faculty of Medicine, GZMB, Georg-August-University Göttingen, Göttingen, Germany,For correspondence: Ralph H. Kehlenbach
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Nakanishi A, Okumura H, Hashita T, Yamashita A, Nishimura Y, Watanabe C, Kamimura S, Hayashi S, Murakami S, Ito K, Iwao T, Ikeda A, Hirose T, Sunazuka T, Tanaka Y, Matsunaga T. Ivermectin Inhibits HBV Entry into the Nucleus by Suppressing KPNA2. Viruses 2022; 14:v14112468. [PMID: 36366568 PMCID: PMC9695645 DOI: 10.3390/v14112468] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/28/2022] [Accepted: 11/04/2022] [Indexed: 11/09/2022] Open
Abstract
Hepatitis B virus (HBV) specifically infects human hepatocytes and increases the risks of cirrhosis and liver cancer. Currently, nucleic acid analogs are the main therapeutics for chronic hepatitis caused by HBV infection. Although nucleic acid analogs can eliminate HBV DNA by inhibiting HBV reverse transcriptase, they cannot lead to negative conversion of covalently closed circular DNA (cccDNA) and hepatitis B surface antigen (HBsAg). In this study, we revealed that the antifilarial drug ivermectin suppresses HBV production by a different mechanism from the nucleic acid analog entecavir or Na+ taurocholate co-transporting polypeptide-mediated entry inhibitor cyclosporin A. Ivermectin reduced the levels of several HBV markers, including HBsAg, in HBV-infected human hepatocellular carcinoma cells (HepG2-hNTCP-C4 cells) and humanized mouse hepatocytes (PXB hepatocytes). In addition, ivermectin significantly decreased the expression of HBV core protein and the nuclear transporter karyopherin α2 (KPNA2) in the nuclei of HepG2-hNTCP-C4 cells. Furthermore, depletion of KPNA1-6 suppressed the production of cccDNA. These results suggest that KPNA1-6 is involved in the nuclear import of HBV and that ivermectin suppresses the nuclear import of HBV by inhibiting KPNA2. This study demonstrates the potential of ivermectin as a novel treatment for hepatitis B.
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Affiliation(s)
- Anna Nakanishi
- Department of Clinical Pharmacy, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Hiroki Okumura
- Department of Clinical Pharmacy, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Tadahiro Hashita
- Department of Clinical Pharmacy, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
- Educational Research Center for Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
- Correspondence: (T.H.); (Y.T.)
| | - Aya Yamashita
- Educational Research Center for Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Yuka Nishimura
- Educational Research Center for Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Chihiro Watanabe
- Educational Research Center for Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Sakina Kamimura
- Educational Research Center for Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Sanae Hayashi
- Department of Virology and Liver Unit, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
- Department of Gastroenterology and Hepatology, Kumamoto University, Kumamoto 860-8556, Japan
| | - Shuko Murakami
- Department of Virology and Liver Unit, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Kyoko Ito
- Department of Virology and Liver Unit, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Takahiro Iwao
- Department of Clinical Pharmacy, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
- Educational Research Center for Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Akari Ikeda
- Ōmura Satoshi Memorial Institute, Graduate School of Infection Control Sciences, Kitasato University, Tokyo 108-8641, Japan
| | - Tomoyasu Hirose
- Ōmura Satoshi Memorial Institute, Graduate School of Infection Control Sciences, Kitasato University, Tokyo 108-8641, Japan
| | - Toshiaki Sunazuka
- Ōmura Satoshi Memorial Institute, Graduate School of Infection Control Sciences, Kitasato University, Tokyo 108-8641, Japan
| | - Yasuhito Tanaka
- Department of Virology and Liver Unit, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
- Department of Gastroenterology and Hepatology, Kumamoto University, Kumamoto 860-8556, Japan
- Correspondence: (T.H.); (Y.T.)
| | - Tamihide Matsunaga
- Department of Clinical Pharmacy, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
- Educational Research Center for Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
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