1
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Lazo PA. Nuclear functions regulated by the VRK1 kinase. Nucleus 2024; 15:2353249. [PMID: 38753965 DOI: 10.1080/19491034.2024.2353249] [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: 04/02/2024] [Accepted: 05/06/2024] [Indexed: 05/18/2024] Open
Abstract
In the nucleus, the VRK1 Ser-Thr kinase is distributed in nucleoplasm and chromatin, where it has different roles. VRK1 expression increases in response to mitogenic signals. VRK1 regulates cyclin D1 expression at G0 exit and facilitates chromosome condensation at the end of G2 and G2/M progression to mitosis. These effects are mediated by the phosphorylation of histone H3 at Thr3 by VRK1, and later in mitosis by haspin. VRK1 regulates the apigenetic patterns of histones in processes requiring chromating remodeling, such as transcription, replication and DNA repair. VRK1 is overexpressed in tumors, facilitating tumor progression and resistance to genotoxic treatments. VRK1 also regulates the organization of Cajal bodies assembled on coilin, which are necessary for the assembly of different types of RNP complexes. VRK1 pathogenic variants cuase defects in Cajal bodies, functionally altering neurons with long axons and leading to neurological diseases, such as amyotrophic laterla sclerosis, spinal muscular atrophy, distal hereditay motor neuropathies and Charcot-Marie-Tooth.
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Affiliation(s)
- Pedro A Lazo
- Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, Salamanca, Spain
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2
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Navarro-Carrasco E, Campos-Díaz A, Monte-Serrano E, Rolfs F, de Goeij-de Haas R, Pham TV, Piersma SR, Jiménez CR, Lazo PA. Loss of VRK1 alters the nuclear phosphoproteome in the DNA damage response to doxorubicin. Chem Biol Interact 2024; 391:110908. [PMID: 38367682 DOI: 10.1016/j.cbi.2024.110908] [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: 11/11/2023] [Revised: 01/22/2024] [Accepted: 02/07/2024] [Indexed: 02/19/2024]
Abstract
Dynamic chromatin remodeling requires regulatory mechanisms for its adaptation to different nuclear function, which are likely to be mediated by signaling proteins. In this context, VRK1 is a nuclear Ser-Thr kinase that regulates pathways associated with transcription, replication, recombination, and DNA repair. Therefore, VRK1 is a potential regulatory, or coordinator, molecule in these processes. In this work we studied the effect that VRK1 depletion has on the basal nuclear and chromatin phosphoproteome, and their associated pathways. VRK1 depletion caused an alteration in the pattern of the nuclear phosphoproteome, which is mainly associated with nucleoproteins, ribonucleoproteins, RNA splicing and processing. Next, it was determined the changes in proteins associated with DNA damage that was induced by doxorubicin treatment. Doxorubicin alters the nuclear phosphoproteome affecting proteins implicated in DDR, including DSB repair proteins NBN and 53BP1, cellular response to stress and chromatin organization proteins. In VRK1-depleted cells, the effect of doxorubicin on protein phosphorylation was reverted to basal levels. The nuclear phosphoproteome patterns induced by doxorubicin are altered by VRK1 depletion, and is enriched in histone modification proteins and chromatin associated proteins. These results indicate that VRK1 plays a major role in processes requiring chromatin remodeling in its adaptation to different biological contexts.
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Affiliation(s)
- Elena Navarro-Carrasco
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad de Salamanca, E-37007, Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, E-37007, Salamanca, Spain.
| | - Aurora Campos-Díaz
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad de Salamanca, E-37007, Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, E-37007, Salamanca, Spain.
| | - Eva Monte-Serrano
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad de Salamanca, E-37007, Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, E-37007, Salamanca, Spain.
| | - Frank Rolfs
- OncoProteomics Laboratory, Cancer Center Amsterdam, Amsterdam UMC, Vrije Universiteit, Amsterdam, the Netherlands.
| | - Richard de Goeij-de Haas
- OncoProteomics Laboratory, Cancer Center Amsterdam, Amsterdam UMC, Vrije Universiteit, Amsterdam, the Netherlands.
| | - Thang V Pham
- OncoProteomics Laboratory, Cancer Center Amsterdam, Amsterdam UMC, Vrije Universiteit, Amsterdam, the Netherlands.
| | - Sander R Piersma
- OncoProteomics Laboratory, Cancer Center Amsterdam, Amsterdam UMC, Vrije Universiteit, Amsterdam, the Netherlands.
| | - Connie R Jiménez
- OncoProteomics Laboratory, Cancer Center Amsterdam, Amsterdam UMC, Vrije Universiteit, Amsterdam, the Netherlands.
| | - Pedro A Lazo
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad de Salamanca, E-37007, Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, E-37007, Salamanca, Spain.
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3
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Puja R, Dutta S, Bose K. Elucidating the interaction of C-terminal domain of Vaccinia-Related Kinase 2A (VRK2A) with B-cell lymphoma-extra Large (Bcl-xL) to decipher its anti-apoptotic role in cancer. Biochem J 2023; 480:1871-1885. [PMID: 37943248 DOI: 10.1042/bcj20230349] [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: 08/24/2023] [Revised: 11/06/2023] [Accepted: 11/09/2023] [Indexed: 11/10/2023]
Abstract
Vaccinia-Related Kinase 2 (VRK2) is an anti-apoptotic Ser/Thr kinase that enhances drug sensitivity in cancer cells. This protein exists in two isoforms: VRK2A, the longer variant, and VRK2B, which lacks the C-terminal region and transmembrane domain. While the therapeutic importance of VRK2 family proteins is known, the specific roles of VRK2A and its interplay with apoptotic regulator Bcl-xL (B-cell lymphoma-extra Large) remain elusive. Bcl-xL regulates cell death by interacting with BAX (B-cell lymphoma-2 Associated X-protein), controlling its cellular localization and influencing BAX-associated processes and signaling pathways. As VRK2A interacts with the Bcl-xL-BAX complex, comprehending its regulatory engagement with Bcl-xL presents potential avenues for intervening in diseases. Using a multi-disciplinary approach, this study provides information on the cellular localization of VRK2A and establishes its interaction with Bcl-xL in the cellular milieu, pinpointing the interacting site and elucidating its anti-apoptotic property within the complex. Furthermore, this study also put forth a model that highlights the importance of VRK2A in stabilizing the ternary complex, formed with Bcl-xL and BAX, thereby impeding BAX dissociation and hence apoptosis. Therefore, further investigations associated with this important revelation will provide cues for designing cancer therapeutics in the future.
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Affiliation(s)
- Rashmi Puja
- Integrated Biophysics and Structural Biology Lab, ACTREC, Tata Memorial Centre, Navi Mumbai 410210, India
- Homi Bhabha National Institute, BARC Training School Complex, Anushaktinagar, Mumbai 400094, India
| | - Shubhankar Dutta
- Integrated Biophysics and Structural Biology Lab, ACTREC, Tata Memorial Centre, Navi Mumbai 410210, India
- Homi Bhabha National Institute, BARC Training School Complex, Anushaktinagar, Mumbai 400094, India
| | - Kakoli Bose
- Integrated Biophysics and Structural Biology Lab, ACTREC, Tata Memorial Centre, Navi Mumbai 410210, India
- Homi Bhabha National Institute, BARC Training School Complex, Anushaktinagar, Mumbai 400094, India
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4
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Umeda R, Teranishi H, Hada K, Shimizu N, Shiraishi H, Urushibata H, Shaohong L, Shide M, Apolinario MEC, Higa R, Shikano K, Shin T, Mimata H, Hikida T, Hanada T, Hanada R. Vrk2 deficiency elicits aggressive behavior in female zebrafish. Genes Cells 2022; 27:254-265. [DOI: 10.1111/gtc.12924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/25/2022] [Accepted: 01/25/2022] [Indexed: 11/29/2022]
Affiliation(s)
- Ryohei Umeda
- Department of Neurophysiology Faculty of Medicine Oita University Oita Japan
| | - Hitoshi Teranishi
- Department of Neurophysiology Faculty of Medicine Oita University Oita Japan
| | - Kazumasa Hada
- Department of Cell Biology Faculty of Medicine Oita University Oita Japan
| | - Nobuyuki Shimizu
- Department of Cell Biology Faculty of Medicine Oita University Oita Japan
| | - Hiroshi Shiraishi
- Department of Cell Biology Faculty of Medicine Oita University Oita Japan
| | | | - Lai Shaohong
- Department of Cell Biology Faculty of Medicine Oita University Oita Japan
| | - Masahito Shide
- Department of Neurophysiology Faculty of Medicine Oita University Oita Japan
| | | | - Ryoko Higa
- Department of Neurophysiology Faculty of Medicine Oita University Oita Japan
| | - Kenshiro Shikano
- Department of Neurophysiology Faculty of Medicine Oita University Oita Japan
| | - Toshitaka Shin
- Department of Urology Faculty of Medicine Oita University Oita Japan
| | - Hiromitsu Mimata
- Department of Urology Faculty of Medicine Oita University Oita Japan
| | - Takatoshi Hikida
- Laboratory for Advanced Brain Functions Institute for Protein Research Osaka University Osaka Japan
| | - Toshikatsu Hanada
- Department of Cell Biology Faculty of Medicine Oita University Oita Japan
| | - Reiko Hanada
- Department of Neurophysiology Faculty of Medicine Oita University Oita Japan
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5
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Chen S, Du Y, Xu B, Li Q, Yang L, Jiang Z, Zeng Z, Chen L. Vaccinia-related kinase 2 blunts sorafenib's efficacy against hepatocellular carcinoma by disturbing the apoptosis-autophagy balance. Oncogene 2021; 40:3378-3393. [PMID: 33875785 DOI: 10.1038/s41388-021-01780-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 03/04/2021] [Accepted: 04/06/2021] [Indexed: 12/16/2022]
Abstract
Hepatocellular carcinoma (HCC) is a lethal malignancy with limited treatment options. Sorafenib is the only Food and Drug Administration (FDA)-approved first-line targeted drug for the treatment of advanced HCC. However, its effect on patient survival is limited. Recently, studies have demonstrated that the imbalance between apoptosis and autophagy plays a critical role in chemoresistance, and it is hypothesised that restoring the balance between these processes is a potential treatment strategy for improving chemoresistance in cancer. However, there is currently no evidence supporting this hypothesis. We aimed to investigate if vaccinia-related kinase 2 (VRK2), a serine/threonine protein kinase, confers sorafenib resistance in HCC cells. Here, we found that VRK2 was enriched in sorafenib-resistant HCC cells and patient-derived xenografts. Both in vivo and in vitro evidences showed that VRK2 blunts the efficacy of sorafenib against hepatocellular carcinoma by disturbing the balance between apoptosis and autophagy. Mechanistically, VRK2 promotes the phosphorylation of Bcl-2 by activating JNK1/MAPK8, thereby enhancing the dissociation of Bcl-2 from Beclin-1 and promoting the formation of the Beclin-1-Atg14-Vps34 complex, which facilitates autophagy. Furthermore, VRK2-induced phosphorylation of Bcl-2 promotes the interaction of Bcl-2 with BAX, thereby inhibiting apoptosis. In conclusion, targeting VRK2 for modulation of the balance between autophagy and apoptosis may be a novel strategy for overcoming sorafenib resistance in HCC.
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Affiliation(s)
- Sisi Chen
- Department of General Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yunyan Du
- Department of Medical, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, China
| | - Bin Xu
- Department of Burns, First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Qing Li
- Department of Pathology, Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Le Yang
- Department of Pharmacy, Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Zi Jiang
- Department of Pharmacy, Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Zhaoxia Zeng
- Department of Radiology, Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Leifeng Chen
- Department of General Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, China.
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6
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Campillo-Marcos I, García-González R, Navarro-Carrasco E, Lazo PA. The human VRK1 chromatin kinase in cancer biology. Cancer Lett 2021; 503:117-128. [PMID: 33516791 DOI: 10.1016/j.canlet.2020.12.032] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/30/2020] [Accepted: 12/21/2020] [Indexed: 01/08/2023]
Abstract
VRK1 is a nuclear Ser-Thr chromatin kinase that does not mutate in cancer, and is overexpressed in many types of tumors and associated with a poor prognosis. Chromatin VRK1 phosphorylates several transcription factors, including p53, histones and proteins implicated in DNA damage response pathways. In the context of cell proliferation, VRK1 regulates entry in cell cycle, chromatin condensation in G2/M, Golgi fragmentation, Cajal body dynamics and nuclear envelope assembly in mitosis. This kinase also controls the initial chromatin relaxation associated with histone acetylation, and the non-homologous-end joining (NHEJ) DNA repair pathway, which involves sequential steps such as γH2AX, NBS1 and 53BP1 foci formation, all phosphorylated by VRK1, in response to ionizing radiation or chemotherapy. In addition, VRK1 can be an alternative target for therapies based on synthetic lethality strategies. Therefore, VRK1 roles on proliferation have a pro-tumorigenic effect. Functions regulating chromatin stability and DNA damage responses have a protective anti-tumor role in normal cells, but in tumor cells can also facilitate resistance to genotoxic treatments.
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Affiliation(s)
- Ignacio Campillo-Marcos
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular Del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad de Salamanca, 37007 Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 37007 Salamanca, Spain.
| | - Raúl García-González
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular Del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad de Salamanca, 37007 Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 37007 Salamanca, Spain.
| | - Elena Navarro-Carrasco
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular Del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad de Salamanca, 37007 Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 37007 Salamanca, Spain.
| | - Pedro A Lazo
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular Del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad de Salamanca, 37007 Salamanca, Spain.
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7
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Colmenero-Repiso A, Gómez-Muñoz MA, Rodríguez-Prieto I, Amador-Álvarez A, Henrich KO, Pascual-Vaca D, Okonechnikov K, Rivas E, Westermann F, Pardal R, Vega FM. Identification of VRK1 as a New Neuroblastoma Tumor Progression Marker Regulating Cell Proliferation. Cancers (Basel) 2020; 12:cancers12113465. [PMID: 33233777 PMCID: PMC7699843 DOI: 10.3390/cancers12113465] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/16/2020] [Accepted: 11/19/2020] [Indexed: 12/31/2022] Open
Abstract
Neuroblastoma (NB) is one of the most common pediatric cancers and presents a poor survival rate in affected children. Current pretreatment risk assessment relies on a few known molecular parameters, like the amplification of the oncogene MYCN. However, a better molecular knowledge about the aggressive progression of the disease is needed to provide new therapeutical targets and prognostic markers and to improve patients' outcomes. The human protein kinase VRK1 phosphorylates various signaling molecules and transcription factors to regulate cell cycle progression and other processes in physiological and pathological situations. Using neuroblastoma tumor expression data, tissue microarrays from fresh human samples and patient-derived xenografts (PDXs), we have determined that VRK1 kinase expression stratifies patients according to tumor aggressiveness and survival, allowing the identification of patients with worse outcome among intermediate risk. VRK1 associates with cell cycle signaling pathways in NB and its downregulation abrogates cell proliferation in vitro and in vivo. Through the analysis of ChIP-seq and methylation data from NB tumors, we show that VRK1 is a MYCN gene target, however VRK1 correlates with NB aggressiveness independently of MYCN gene amplification, synergizing with the oncogene to drive NB progression. Our study also suggests that VRK1 inhibition may constitute a novel cell-cycle-targeted strategy for anticancer therapy in neuroblastoma.
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Affiliation(s)
- Ana Colmenero-Repiso
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain; (A.C.-R.); (M.A.G.-M.); (I.R.-P.); (A.A.-Á.)
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, 41013 Seville, Spain
| | - María A. Gómez-Muñoz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain; (A.C.-R.); (M.A.G.-M.); (I.R.-P.); (A.A.-Á.)
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, 41013 Seville, Spain
| | - Ismael Rodríguez-Prieto
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain; (A.C.-R.); (M.A.G.-M.); (I.R.-P.); (A.A.-Á.)
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, 41013 Seville, Spain
| | - Aida Amador-Álvarez
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain; (A.C.-R.); (M.A.G.-M.); (I.R.-P.); (A.A.-Á.)
- Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Kai-Oliver Henrich
- German Cancer Research Center (DKFZ), Division Neuroblastoma Genomics, 69120 Heidelberg, Germany; (K.-O.H.); (F.W.)
| | - Diego Pascual-Vaca
- Departamento de Anatomía Patológica, Hospital Universitario Virgen del Rocío, 41013 Sevilla, Spain; (D.P.-V.); (E.R.)
| | | | - Eloy Rivas
- Departamento de Anatomía Patológica, Hospital Universitario Virgen del Rocío, 41013 Sevilla, Spain; (D.P.-V.); (E.R.)
| | - Frank Westermann
- German Cancer Research Center (DKFZ), Division Neuroblastoma Genomics, 69120 Heidelberg, Germany; (K.-O.H.); (F.W.)
| | - Ricardo Pardal
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain; (A.C.-R.); (M.A.G.-M.); (I.R.-P.); (A.A.-Á.)
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, 41013 Seville, Spain
- Correspondence: (R.P.); (F.M.V.)
| | - Francisco M. Vega
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain; (A.C.-R.); (M.A.G.-M.); (I.R.-P.); (A.A.-Á.)
- Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
- Correspondence: (R.P.); (F.M.V.)
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8
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Ren Z, Geng J, Xiong C, Li X, Li Y, Li J, Liu H. Downregulation of VRK1 reduces the expression of BANF1 and suppresses the proliferative and migratory activity of esophageal cancer cells. Oncol Lett 2020; 20:1163-1170. [PMID: 32724356 PMCID: PMC7377186 DOI: 10.3892/ol.2020.11654] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 04/15/2020] [Indexed: 02/05/2023] Open
Abstract
Esophageal squamous cell carcinoma (ESCC) is a common malignancy worldwide. The disease has a poor prognosis and a low 5-year survival rate. Therefore, it is necessary to identify new strategies to optimize the treatment of ESCC. Vaccinia-related kinase (VRK1) and barrier-to-autointegration factor 1 (BANF1) are overexpressed in ESCC. In the present study, the roles of VRK1 and BANF1 were explored in the development of ESCC. In the present study, the effects of small interfering (si)RNA-induced downregulation of VRK1 on BANF1 expression were investigated as well as the effects on proliferative and migratory activity of ESCC cells. Western blot analysis indicated that the protein expression levels of BANF1 were decreased following siRNA depletion of VRK1. Furthermore, the depletion of VRK1 expression inhibited the proliferation and migration of ESCC cell lines, and flow cytometry analysis indicated that the depletion of VRK1 triggered cell cycle arrest mainly in the S phase. These results suggested that VRK1 and BANF1 may have pivotal roles in the progression of ESCC.
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Affiliation(s)
- Zhenzhen Ren
- Department of Medical Laboratory, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Jie Geng
- Department of Medical Laboratory, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Chao Xiong
- Department of Medical Laboratory, The Second Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou, Henan 450052, P.R. China
| | - Xuebing Li
- Department of Medical Laboratory, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Yuqing Li
- Department of Medical Laboratory, The Second Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou, Henan 450052, P.R. China
| | - Jin Li
- Department of Medical Laboratory, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Hongchun Liu
- Department of Medical Laboratory, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
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9
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Phosphoproteomic analyses of kidneys of Atlantic salmon infected with Aeromonas salmonicida. Sci Rep 2019; 9:2101. [PMID: 30765835 PMCID: PMC6376026 DOI: 10.1038/s41598-019-38890-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 01/09/2019] [Indexed: 11/08/2022] Open
Abstract
Aeromonas salmonicida (A. salmonicida) is a pathogenic bacterium that causes furunculosis and poses a significant global risk, particularly in economic activities such as Atlantic salmon (Salmo salar) farming. In a previous study, we identified proteins that are significantly upregulated in kidneys of Atlantic salmon challenged with A. salmonicida. Phosphoproteomic analyses were conducted to further clarify the dynamic changes in protein phosphorylation patterns triggered by bacterial infection. To our knowledge, this is the first study to characterize phosphorylation events in proteins from A. salmonicida-infected Atlantic salmon. Overall, we identified over 5635 phosphorylation sites in 3112 proteins, and 1502 up-regulated and 77 down-regulated proteins quantified as a 1.5-fold or greater change relative to control levels. Based on the combined data from proteomic and motif analyses, we hypothesize that five prospective novel kinases (VRK3, GAK, HCK, PKCδ and RSK6) with common functions in inflammatory processes and cellular pathways to regulate apoptosis and the cytoskeleton could serve as potential biomarkers against bacterial propagation in fish. Data from STRING-based functional network analyses indicate that fga is the most central protein. Our collective findings provide new insights into protein phosphorylation patterns, which may serve as effective indicators of A. salmonicida infection in Atlantic salmon.
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10
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Li M, Yue W. VRK2, a Candidate Gene for Psychiatric and Neurological Disorders. MOLECULAR NEUROPSYCHIATRY 2018; 4:119-133. [PMID: 30643786 PMCID: PMC6323383 DOI: 10.1159/000493941] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 09/20/2018] [Indexed: 12/20/2022]
Abstract
Recent large-scale genetic approaches, such as genome-wide association studies, have identified multiple genetic variations that contribute to the risk of mental illnesses, among which single nucleotide polymorphisms (SNPs) within or near the vaccinia related kinase 2 (VRK2) gene have gained consistent support for their correlations with multiple psychiatric and neurological disorders including schizophrenia (SCZ), major depressive disorder (MDD), and genetic generalized epilepsy. For instance, the genetic variant rs1518395 in VRK2 showed genome-wide significant associations with SCZ (35,476 cases and 46,839 controls, p = 3.43 × 10-8) and MDD (130,620 cases and 347,620 controls, p = 4.32 × 10-12) in European populations. This SNP was also genome-wide significantly associated with SCZ in Han Chinese population (12,083 cases and 24,097 controls, p = 3.78 × 10-13), and all associations were in the same direction of allelic effects. These studies highlight the potential roles of VRK2 in the central nervous system, and this gene therefore might be a good candidate to investigate the shared genetic and molecular basis between SCZ and MDD, as it is one of the few genes known to show genome-wide significant associations with both illnesses. Furthermore, the VRK2 gene was found to be involved in multiple other congenital deficits related to the malfunction of neurodevelopment, adding further support for the involvement of this gene in the pathogenesis of these neurological and psychiatric illnesses. While the precise function of VRK2 in these conditions remains unclear, preliminary evidence suggests that it may affect neuronal proliferation and migration via interacting with multiple essential signaling pathways involving other susceptibility genes/proteins for psychiatric disorders. Here, we have reviewed the recent progress of genetic and molecular studies of VRK2, with an emphasis on its role in psychiatric illnesses and neurological functions. We believe that attention to this important gene is necessary, and further investigations of VRK2 may provide hints into the underlying mechanisms of SCZ and MDD.
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Affiliation(s)
- Ming Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Kunming, China
- CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Weihua Yue
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, China
- Key Laboratory of Mental Health, Ministry of Health (Peking University) and National Clinical Research Center for Mental Disorders (Peking University Sixth Hospital), Beijing, China
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11
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Overexpression of the VRK1 kinase, which is associated with breast cancer, induces a mesenchymal to epithelial transition in mammary epithelial cells. PLoS One 2018; 13:e0203397. [PMID: 30180179 PMCID: PMC6122820 DOI: 10.1371/journal.pone.0203397] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/20/2018] [Indexed: 01/23/2023] Open
Abstract
Vaccinia-related kinase 1 (VRK1) is a pro-proliferative nuclear kinase. Mice engrafted with VRK1-depleted MDA-MB-231 breast cancer cells have been shown to develop fewer distal metastases than controls, suggesting VRK1 might play a role in cell migration, invasion, and/or colonization. In work described herein, we investigated the impact of VRK1 overexpression on human mammary epithelial cells. In 2D culture, VRK1 overexpression diminishes cell migration and invasion and impairs the migration-associated processes of cell spreading and cytoskeletal rearrangement. VRK1-overexpressing cells show reduced accumulation of the mesenchymal marker vimentin and increased accumulation of the epithelial markers E-cadherin and claudin-1. VRK1 overexpression also leads to reduced levels of the transcriptional repressors snail, slug, and twist1. Cumulatively, these data indicate that VRK1 overexpression augments the epithelial properties of both MCF10a and MDA-MB-231 cells. We further studied the impact of VRK1 on the epithelial properties of MCF10a cells in 3D matrigel culture, in which cells proliferate and form epithelial sheets that mature into hollow spherical acini. VRK1 overexpression significantly accelerates the initial stages of cell proliferation, leading to larger acini that nevertheless differentiate and mature. Our analysis of human tumor tissue microarrays (TMAs) revealed that VRK1 protein levels are higher in lymph node metastases than in patient-matched mammary tumors. Using public databases, we determined that VRK1 is among the top 10% of overexpressed transcripts in multiple subtypes of invasive breast cancer, and that high levels of VRK1 expression are correlated with decreased relapse-free survival. In sum, overexpression of VRK1, by regulating the transcription repressors snail, slug, and twist1, can promote a mesenchymal-to-epithelial transition (MET) in cell culture. VRK1-mediated MET might facilitate the colonization of distal sites by metastatic breast cancer cells, providing some insight into the frequent association of VRK1 overexpression with breast malignancies and the correlation between VRK1 overexpression and poor clinical outcome.
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12
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Campillo-Marcos I, Lazo PA. Implication of the VRK1 chromatin kinase in the signaling responses to DNA damage: a therapeutic target? Cell Mol Life Sci 2018; 75:2375-2388. [PMID: 29679095 PMCID: PMC5986855 DOI: 10.1007/s00018-018-2811-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 03/14/2018] [Accepted: 04/03/2018] [Indexed: 12/19/2022]
Abstract
DNA damage causes a local distortion of chromatin that triggers the sequential processes that participate in specific DNA repair mechanisms. This initiation of the repair response requires the involvement of a protein whose activity can be regulated by histones. Kinases are candidates to regulate and coordinate the connection between a locally altered chromatin and the response initiating signals that lead to identification of the type of lesion and the sequential steps required in specific DNA damage responses (DDR). This initiating kinase must be located in chromatin, and be activated independently of the type of DNA damage. We review the contribution of the Ser-Thr vaccinia-related kinase 1 (VRK1) chromatin kinase as a new player in the signaling of DNA damage responses, at chromatin and cellular levels, and its potential as a new therapeutic target in oncology. VRK1 is involved in the regulation of histone modifications, such as histone phosphorylation and acetylation, and in the formation of γH2AX, NBS1 and 53BP1 foci induced in DDR. Induction of DNA damage by chemotherapy or radiation is a mainstay of cancer treatment. Therefore, novel treatments can be targeted to proteins implicated in the regulation of DDR, rather than by directly causing DNA damage.
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Affiliation(s)
- Ignacio Campillo-Marcos
- Experimental Therapeutics and Translational Oncology Program, Instituto de Biología Molecular y Celular del Cáncer, CSIC-Universidad de Salamanca, 37007, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 37007, Salamanca, Spain
| | - Pedro A Lazo
- Experimental Therapeutics and Translational Oncology Program, Instituto de Biología Molecular y Celular del Cáncer, CSIC-Universidad de Salamanca, 37007, Salamanca, Spain.
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 37007, Salamanca, Spain.
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13
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Couñago RM, Allerston CK, Savitsky P, Azevedo H, Godoi PH, Wells CI, Mascarello A, de Souza Gama FH, Massirer KB, Zuercher WJ, Guimarães CRW, Gileadi O. Structural characterization of human Vaccinia-Related Kinases (VRK) bound to small-molecule inhibitors identifies different P-loop conformations. Sci Rep 2017; 7:7501. [PMID: 28790404 PMCID: PMC5548783 DOI: 10.1038/s41598-017-07755-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 06/29/2017] [Indexed: 11/12/2022] Open
Abstract
The human genome encodes two active Vaccinia-related protein kinases (VRK), VRK1 and VRK2. These proteins have been implicated in a number of cellular processes and linked to a variety of tumors. However, understanding the cellular role of VRKs and establishing their potential use as targets for therapeutic intervention has been limited by the lack of tool compounds that can specifically modulate the activity of these kinases in cells. Here we identified BI-D1870, a dihydropteridine inhibitor of RSK kinases, as a promising starting point for the development of chemical probes targeting the active VRKs. We solved co-crystal structures of both VRK1 and VRK2 bound to BI-D1870 and of VRK1 bound to two broad-spectrum inhibitors. These structures revealed that both VRKs can adopt a P-loop folded conformation, which is stabilized by different mechanisms on each protein. Based on these structures, we suggest modifications to the dihydropteridine scaffold that can be explored to produce potent and specific inhibitors towards VRK1 and VRK2.
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Affiliation(s)
- Rafael M Couñago
- Structural Genomics Consortium, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil. .,Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, SP, Brazil.
| | - Charles K Allerston
- Structural Genomics Consortium and Target Discovery Institute, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, UK
| | - Pavel Savitsky
- Structural Genomics Consortium and Target Discovery Institute, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, UK
| | | | - Paulo H Godoi
- Structural Genomics Consortium, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil.,Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas, Campinas, Brazil
| | - Carrow I Wells
- Structural Genomics Consortium, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | | | - Katlin B Massirer
- Structural Genomics Consortium, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil.,Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - William J Zuercher
- Structural Genomics Consortium, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - Opher Gileadi
- Structural Genomics Consortium, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil.,Structural Genomics Consortium and Target Discovery Institute, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, UK
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14
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Liu ZC, Cao K, Xiao ZH, Qiao L, Wang XQ, Shang B, Jia Y, Wang Z. VRK1 promotes cisplatin resistance by up-regulating c-MYC via c-Jun activation and serves as a therapeutic target in esophageal squamous cell carcinoma. Oncotarget 2017; 8:65642-65658. [PMID: 29029460 PMCID: PMC5630360 DOI: 10.18632/oncotarget.20020] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 07/25/2017] [Indexed: 11/25/2022] Open
Abstract
Esophageal squamous cell carcinoma (ESCC) is a common malignant disease characterized by poor prognosis. Chemoresistance remains a major cause of ESCC relapse. Vaccinia-related kinase 1 (VRK1) has previously been identified as a cancer-related gene. However, there is little research demonstrating an association between VRK1 and ESCC. In this study, we show that VRK1 is overexpressed in ESCC primary tumor samples and cell lines. VRK1 expression was significantly correlated with clinical characteristics and predicted poor outcomes in ESCC patients. Functionally, knockdown of VRK1 inhibited ESCC cell proliferation, survival, migration and invasion; conversely, VRK1 overexpression produced the opposite effects. Furthermore, we found that up-regulation of VRK1 promoted cisplatin (CDDP) resistance in ESCC both in vitro and in vivo, whereas knockdown of VRK1 reduced this resistance. Further studies verified that VRK1 phosphorylated c-Jun and that the VRK1/c-Jun pathway contributed to CDDP resistance in ESCC. Mechanistically, a dual luciferase reporter assay revealed that c-Jun transcriptionally activated the expression of c-MYC. Silencing c-MYC abolished the c-Jun-mediated CDDP resistance of ESCC cells. A Kaplan-Meier analysis indicated that c-MYC is a potential prognostic factor in ESCC. Finally, luteolin, a VRK1 inhibitor, attenuated the malignant biological behaviors and CDDP resistance in ESCC cells. Collectively, we conclude that VRK1 promotes CDDP resistance through c-MYC by activating c-Jun and potentiating a malignant phenotype in ESCC. Our studies provide novel insight into the role of VRK1 in carcinogenesis and indicate that VRK1 can serve as a potential therapeutic target in ESCC.
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Affiliation(s)
- Zhen-Chuan Liu
- Department of Thoracic Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - Kuo Cao
- Department of Thoracic Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - Zhao-Hua Xiao
- Department of Thoracic Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - Liang Qiao
- Department of Thoracic Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - Xue-Qing Wang
- Department of Thoracic Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - Bin Shang
- Department of Thoracic Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - Yang Jia
- Department of Thoracic Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
| | - Zhou Wang
- Department of Thoracic Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, China
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15
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Park N, Song J, Jeong S, Thi Tran T, Ko HW, Kim EY. Vaccinia-related kinase 3 (VRK3) sets the circadian period and amplitude by affecting the subcellular localization of clock proteins in mammalian cells. Biochem Biophys Res Commun 2017; 487:320-326. [PMID: 28412365 DOI: 10.1016/j.bbrc.2017.04.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 04/09/2017] [Indexed: 11/26/2022]
Abstract
In the eukaryotic circadian clock machinery, negative feedback repression of CLOCK (CLK) and BMAL1 transcriptional activity by PERIOD (PER) and CRYPTOCHROME (CRY) underlies the basis for 24 h rhythmic gene expression. Thus, precise regulation of the time-dependent nuclear entry of circadian repressors is crucial to generating normal circadian rhythms. Here, we sought to identify novel kinase(s) that regulate nuclear entry of mammalian CRY1 (mCRY1) with an unbiased screening using red fluorescent protein (RFP)-tagged human kinome expression plasmids in mammalian cells. Transient expression of human vaccinia-related kinase 3 (hVRK3) reduced the nuclear presence of mCRY1. hVRK3 expression also induced alterations in the subcellular localization of other core clock proteins, including mCRY2, mPER2, and BMAL1. In contrast, the subcellular localization of mCLK was not changed. Given that singly expressed mCLK mostly resides in the cytoplasm and that nuclear localization sequence (NLS) mutation of hVRK3 attenuated the effect of hVRK3 co-expression on subcellular localization, ectopically expressed hVRK3 presumably reduces the retention of proteins in the nucleus. Finally, downregulation of hvrk3 using siRNA reduced the amplitude and lengthened the period of the cellular bioluminescence rhythm. Taken together, these data suggest that VRK3 plays a role in setting the amplitude and period length of circadian rhythms in mammalian cells.
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Affiliation(s)
- Nayoung Park
- Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University School of Medicine, 164 Worldcup-ro, Yeongtong-gu, Suwon, Kyunggi-do, 16499, Republic of Korea; Department of Brain Science, Ajou University School of Medicine, 164 Worldcup-ro, Yeongtong-gu, Suwon, Kyunggi-do, 16499, Republic of Korea
| | - Jieun Song
- College of Pharmacy, Dongguk University-Seoul, 32 Donggukro, Ilsandonggu, Goyangsi, Gyeonggido, 410-820, Republic of Korea
| | - Seongsu Jeong
- Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University School of Medicine, 164 Worldcup-ro, Yeongtong-gu, Suwon, Kyunggi-do, 16499, Republic of Korea; Department of Brain Science, Ajou University School of Medicine, 164 Worldcup-ro, Yeongtong-gu, Suwon, Kyunggi-do, 16499, Republic of Korea
| | - Thanh Thi Tran
- College of Pharmacy, Dongguk University-Seoul, 32 Donggukro, Ilsandonggu, Goyangsi, Gyeonggido, 410-820, Republic of Korea
| | - Hyuk Wan Ko
- College of Pharmacy, Dongguk University-Seoul, 32 Donggukro, Ilsandonggu, Goyangsi, Gyeonggido, 410-820, Republic of Korea
| | - Eun Young Kim
- Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University School of Medicine, 164 Worldcup-ro, Yeongtong-gu, Suwon, Kyunggi-do, 16499, Republic of Korea; Department of Brain Science, Ajou University School of Medicine, 164 Worldcup-ro, Yeongtong-gu, Suwon, Kyunggi-do, 16499, Republic of Korea.
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16
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Huang W, Cui X, Chen Y, Shao M, Shao X, Shen Y, Liu Q, Wu M, Liu J, Ni W, Lu C, Wan C. High VRK1 expression contributes to cell proliferation and survival in hepatocellular carcinoma. Pathol Res Pract 2015; 212:171-8. [PMID: 26706601 DOI: 10.1016/j.prp.2015.11.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 10/28/2015] [Accepted: 11/24/2015] [Indexed: 12/14/2022]
Abstract
VRK1 is a member of the vaccinia-related kinase (VRK) family of serine/threonine protein kinases, which is known to play multiple roles in cellular proliferation, cell cycle regulation and carcinogenesis. However, the expression and physiological significance of VRK1 in hepatocellular carcinoma (HCC) remain unclear. In this study, we aimed to investigate the potential role of VRK1 in the development and progression of HCC. Western blot and immunohistochemical analysis revealed that VRK1 was highly expressed in HCC tissues and cell lines, compared with adjacent nontumorous tissues and LO2 normal hepatocytes. Meanwhile, clinicopathological analysis showed that VRK1 was significantly associated with AJCC stage, Ki-67 and a poor prognosis in HCC specimens. Univariate and multivariate analysis showed that VRK1 could serve as an independent prognostic indicator of HCC patients' survival. Furthermore, we found that VRK1 was lowly expressed in serum-starved Huh7 cells, and was progressively increased after serum-refeeding. Finally, flow cytometry, CCK-8 and colony formation assay indicated that the depletion of VRK1 could retard cell cycle progression and reduce cells proliferation in HCC cells. On the basis of these findings, we conclude that VRK1 may be a candidate prognostic biomarker as well as a potential therapeutical target of HCC.
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Affiliation(s)
- Wei Huang
- Department of Gastroenterology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China
| | - Xiaopeng Cui
- Department of general surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China
| | - Yuyan Chen
- Class 5, Grade 13, Clinical Medicine, Medical College, Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China
| | - Mengting Shao
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China
| | - Xian Shao
- Department of general surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China
| | - Yifen Shen
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China
| | - Qingqing Liu
- Department of Gastroenterology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China
| | - Miaomiao Wu
- Department of Gastroenterology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China
| | - Jinxia Liu
- Department of Gastroenterology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China
| | - Wenkai Ni
- Department of Gastroenterology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China
| | - Cuihua Lu
- Department of Gastroenterology, Affiliated Hospital of Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China.
| | - Chunhua Wan
- Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Nantong University, Nantong, Jiangsu Province, 226001 People's Republic of China.
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17
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Molecular genetic analysis of VRK1 in mammary epithelial cells: depletion slows proliferation in vitro and tumor growth and metastasis in vivo. Oncogenesis 2013; 2:e48. [PMID: 23732708 PMCID: PMC3740298 DOI: 10.1038/oncsis.2013.11] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The vaccinia-related kinases (VRKs) comprise a branch of the casein kinase family. VRK1, a ser/thr kinase with a nuclear localization, is the most well-studied paralog and has been described as a proproliferative protein. In lower eukaryotes, a loss of VRK1 activity is associated with severe mitotic and meiotic defects. Mice that are hypomorphic for VRK1 expression are infertile, and depletion of VRK1 in tissue culture cells can impair cell proliferation and alter several signaling pathways. VRK1 has been implicated as part of a ‘gene-expression signature' whose overexpression correlates with poor clinical outcome in breast cancer patients. We present here our investigation of the role of VRK1 in the growth of normal (MCF10) and malignant (MDA-MB-231) human mammary epithelial cells, and demonstrate that shRNA-mediated depletion of VRK1 slows their proliferation significantly. Conversely, stable overexpression of a FLAG-tagged VRK1 transgene imparts a survival advantage to highly malignant MDA-MB-231 cells under conditions of nutrient and growth factor deprivation. Moreover, in a murine orthotopic xenograft model of breast cancer, we demonstrate that tumors depleted of VRK1 show a 50% reduction in size from 4–13 weeks postengraftment. The incidence and burden of distal metastases in the lungs and brain was also significantly reduced in mice engrafted with VRK1-depleted cells. These studies demonstrate that VRK1 depletion or overexpression has an impact on the proliferation and survival of cell lines derived from normal or malignant mammary tissue, and moreover show that depletion of VRK1 in MDA-MB-231 cells reduces their oncogenic and metastatic properties in vivo.
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18
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Barcia-Sanjurjo I, Vázquez-Cedeira M, Barcia R, Lazo PA. Sensitivity of the kinase activity of human vaccinia-related kinase proteins to toxic metals. J Biol Inorg Chem 2013; 18:473-82. [DOI: 10.1007/s00775-013-0992-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 02/26/2013] [Indexed: 01/22/2023]
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Vázquez-Cedeira M, Lazo PA. Human VRK2 (vaccinia-related kinase 2) modulates tumor cell invasion by hyperactivation of NFAT1 and expression of cyclooxygenase-2. J Biol Chem 2012; 287:42739-50. [PMID: 23105117 DOI: 10.1074/jbc.m112.404285] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Human VRK2 (vaccinia-related kinase 2), a kinase that emerged late in evolution, affects different signaling pathways, and some carcinomas express high levels of VRK2. Invasion by cancer cells has been associated with NFAT1 (nuclear factor of activated T cells) activation and expression of the COX-2 (cyclooxygenase 2) gene. We hypothesized that VRK proteins might play a regulatory role in NFAT1 activation in tumor cells. We demonstrate that VRK2 directly interacts and phosphorylates NFAT1 in Ser-32 within its N-terminal transactivation domain. VRK2 increases NFAT1-dependent transcription by phosphorylation, and this effect is only detected following cell phorbol 12-myristate 13-acetate and ionomycin stimulation and calcineurin activation. This NFAT1 hyperactivation by VRK2 increases COX-2 gene expression through the proximal NFAT1 binding site in the COX-2 gene promoter. Furthermore, VRK2A down-regulation by RNA interference reduces COX-2 expression at transcriptional and protein levels. Therefore, VRK2 down-regulation reduces cell invasion by tumor cells, such as MDA-MB-231 and MDA-MB-435, upon stimulation with phorbol 12-myristate 13-acetate plus ionomycin. These findings identify the first reported target and function of human VRK2 as an active kinase playing a role in regulation of cancer cell invasion through the NFAT pathway and COX-2 expression.
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Affiliation(s)
- Marta Vázquez-Cedeira
- Experimental Therapeutics and Translational Oncology Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas, Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain
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20
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Choi YH, Lim JK, Jeong MW, Kim KT. HnRNP A1 phosphorylated by VRK1 stimulates telomerase and its binding to telomeric DNA sequence. Nucleic Acids Res 2012; 40:8499-518. [PMID: 22740652 PMCID: PMC3458570 DOI: 10.1093/nar/gks634] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The telomere integrity is maintained via replication machinery, telomere associated proteins and telomerase. Many telomere associated proteins are regulated in a cell cycle-dependent manner. Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1), a single-stranded oligonucleotide binding protein, is thought to play a pivotal role in telomere maintenance. Here, we identified hnRNP A1 as a novel substrate for vaccinia-related kinase 1 (VRK1), a cell cycle regulating kinase. Phosphorylation by VRK1 potentiates the binding of hnRNP A1 to telomeric ssDNA and telomerase RNA in vitro and enhances its function for telomerase reaction. VRK1 deficiency induces a shortening of telomeres with an abnormal telomere arrangement and activation of DNA-damage signaling in mouse male germ cells. Together, our data suggest that VRK1 is required for telomere maintenance via phosphorylation of hnRNP A1, which regulates proteins associated with the telomere and telomerase RNA.
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Affiliation(s)
- Yoon Ha Choi
- Department of Life Science, Division of Molecular and Life Science, Pohang University of Science and Technology (POSTECH), San-31, Hyoja-Dong, Pohang 790-784, Republic of Korea
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21
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The bottleneck of JNK signaling: Molecular and functional characteristics of MKK4 and MKK7. Eur J Cell Biol 2011; 90:536-44. [DOI: 10.1016/j.ejcb.2010.11.008] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 11/23/2010] [Accepted: 11/26/2010] [Indexed: 12/18/2022] Open
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Valbuena A, Sanz-García M, López-Sánchez I, Vega FM, Lazo PA. Roles of VRK1 as a new player in the control of biological processes required for cell division. Cell Signal 2011; 23:1267-72. [PMID: 21514377 DOI: 10.1016/j.cellsig.2011.04.002] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 04/04/2011] [Indexed: 11/28/2022]
Abstract
Cell division, in addition to an accurate transmission of genetic information to daughter cells, also requires the temporal and spatial coordination of several biological processes without which cell division would not be feasible. These processes include the temporal coordination of DNA replication and chromosome segregation, regulation of nuclear envelope disassembly and assembly, chromatin condensation and Golgi fragmentation for its redistribution into daughter cells, among others. However, little is known regarding regulatory proteins and signalling pathways that might participate in the coordination of all these different biological functions. Such regulatory players should directly have a role in the processes leading to cell division. VRK1 (Vaccinia-related kinase 1) is an early response gene required for cyclin D1 expression, regulates p53 by a specific Thr18 phosphorylation, controls chromatin condensation by histone phosphorylation, nuclear envelope assembly by phosphorylation of BANF1, and participates in signalling required for Golgi fragmentation late in the G2 phase. We propose that VRK1, a Ser-Thr kinase, might be a candidate to play an important coordinator role in these cell division processes as part of a novel signalling pathway.
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Affiliation(s)
- Alberto Valbuena
- Experimental Therapeutics and Translational Oncology Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain
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23
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Choi YH, Park CH, Kim W, Ling H, Kang A, Chang MW, Im SK, Jeong HW, Kong YY, Kim KT. Vaccinia-related kinase 1 is required for the maintenance of undifferentiated spermatogonia in mouse male germ cells. PLoS One 2010; 5:e15254. [PMID: 21179456 PMCID: PMC3001494 DOI: 10.1371/journal.pone.0015254] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Accepted: 11/02/2010] [Indexed: 11/18/2022] Open
Abstract
Vaccinia-related kinase 1 (VRK1) is a crucial protein kinase for mitotic regulation. VRK1 is known to play a role in germ cell development, and its deficiency results in sterility. Here we describe that VRK1 is essential for the maintenance of spermatogonial stem cells. To determine whether VRK1 plays a role in these cells, we assessed the population size of undifferentiated spermatogonia. Flow cytometry analyses showed that the number of undifferentiated spermatogonia was markedly reduced in VRK1-deficient testes. VRK1 was highly expressed in spermatogonial populations, and approximately 66% of undifferentiated spermatogonia that were sorted as an Ep-CAM+/c-kit−/alpha-6-integrin+ population showed a positive signal for VRK1. Undifferentiated stem cells expressing Plzf and Oct4 but not c-kit also expressed VRK1, suggesting that VRK1 is an intrinsic factor for the maintenance of spermatogonial stem cells. Microarray analyses of the global testicular transcriptome and quantitative RT-PCR of VRK1-deficient testes revealed significantly reduced expression levels of undifferentiated spermatogonial marker genes in early postnatal mice. Together, these results suggest that VRK1 is required for the proliferation and differentiation of undifferentiated spermatogonia, which are essential for spermatogenic cell maintenance.
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Affiliation(s)
- Yoon Ha Choi
- Division of Molecular and Life Science, Department of Life Science, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Choon-Ho Park
- Division of Molecular and Life Science, Department of Life Science, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Wanil Kim
- Division of Molecular and Life Science, Department of Life Science, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Hua Ling
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, Singapore
| | - Aram Kang
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, Singapore
| | - Matthew Wook Chang
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, Singapore
| | - Sun-Kyoung Im
- Division of Molecular and Life Science, Department of Life Science, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Hyun-Woo Jeong
- Division of Molecular and Life Science, Department of Life Science, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
| | - Young-Yun Kong
- Department of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Kyong-Tai Kim
- Division of Molecular and Life Science, Department of Life Science, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
- Division of Integrative Bioscience and Biotechnology, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
- * E-mail:
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VRK2 inhibits mitogen-activated protein kinase signaling and inversely correlates with ErbB2 in human breast cancer. Mol Cell Biol 2010; 30:4687-97. [PMID: 20679487 DOI: 10.1128/mcb.01581-09] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The epidermal growth factor (EGF)-ErbB-mitogen-activated protein kinase (MAPK) transcription signaling pathway is altered in many types of carcinomas, and this pathway can be regulated by new protein-protein interactions. Vaccinia-related kinase (VRK) proteins are Ser-Thr kinases that regulate several signal transduction pathways. In this work, we study the effect of VRK2 on MAPK signaling using breast cancer as a model. High levels of VRK2 inhibit EGF and ErbB2 activation of transcription by the serum response element (SRE). This effect is also detected in response to H-Ras(G12V) or B-Raf(V600E) oncogenes and is accompanied by a reduction in phosphorylated extracellular signal-regulated kinase (ERK) levels, p90RSK levels, and SRE-dependent transcription. Furthermore, VRK2 knockdown has the opposite effect, increasing the transcriptional response to stimulation with EGF and leading to increased levels of ERK phosphorylation. The molecular mechanism lies between MAPK/ERK kinase (MEK) and ERK, since MEK remains phosphorylated while ERK phosphorylation is blocked by VRK2A. This inhibition of the ERK signaling pathway is a consequence of a direct protein-protein interaction between VRK2A, MEK, and kinase suppressor of Ras 1 (KSR1). Identification of new correlations in human cancer can lead to a better understanding of the biology of individual tumors. ErbB2 and VRK2 protein levels were inversely correlated in 136 cases of human breast carcinoma. In ErbB2(+) tumors, there is a significant reduction in the VRK2 level, suggesting a role for VRK2A in ErbB2-MAPK signaling. Thus, VRK2 downregulation in carcinomas permits signal transmission through the MEK-ERK pathway without affecting AKT signaling, causing a signal imbalance among pathways that contributes to the phenotype of breast cancer.
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Suzuki Y, Ogawa K, Koyanagi Y, Suzuki Y. Functional disruption of the moloney murine leukemia virus preintegration complex by vaccinia-related kinases. J Biol Chem 2010; 285:24032-43. [PMID: 20511217 DOI: 10.1074/jbc.m110.116640] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retroviral integration is executed by the preintegration complex (PIC), which contains viral DNA together with a number of proteins. Barrier-to-autointegration factor (BAF), a cellular component of Moloney murine leukemia virus (MMLV) PICs, has been demonstrated to protect viral DNA from autointegration and stimulate the intermolecular integration activity of the PIC by its DNA binding activity. Recent studies reveal that the functions of BAF are regulated by phosphorylation via a family of cellular serine/threonine kinases called vaccinia-related kinases (VRK), and VRK-mediated phosphorylation causes a loss of the DNA binding activity of BAF. These results raise the possibility that BAF phosphorylation may influence the integration activities of the PIC through removal of BAF from viral DNA. In the present study, we report that VRK1 was able to abolish the intermolecular integration activity of MMLV PICs in vitro. This was accompanied by an enhancement of autointegration activity and dissociation of BAF from the PICs. In addition, in vitro phosphorylation of BAF by VRK1 abrogated the activity of BAF in PIC function. Among the VRK family members, VRK1 as well as VRK2, which catalyze hyperphosphorylation of BAF, could abolish PIC function. We also found that treatment of PICs with certain nucleotides such as ATP resulted in the inhibition of the intermolecular integration activity of PICs through the dissociation of BAF. More importantly, the ATP-induced disruption was not observed with the PICs from VRK1 knockdown cells. Our in vitro results therefore suggest the presence of cellular kinases including VRKs that can inactivate the retroviral integration complex via BAF phosphorylation.
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Affiliation(s)
- Yasutsugu Suzuki
- Laboratory for Host Factors, Center for Emerging Virus Research, Kyoto University, Kyoto 606-8507, Japan.
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Staphylococcal PknB as the first prokaryotic representative of the proline-directed kinases. PLoS One 2010; 5:e9057. [PMID: 20140229 PMCID: PMC2816222 DOI: 10.1371/journal.pone.0009057] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Accepted: 01/18/2010] [Indexed: 01/25/2023] Open
Abstract
In eukaryotic cell types, virtually all cellular processes are under control of proline-directed kinases and especially MAP kinases. Serine/threonine kinases in general were originally considered as a eukaryote-specific enzyme family. However, recent studies have revealed that orthologues of eukaryotic serine/threonine kinases exist in bacteria. Moreover, various pathogenic species, such as Yersinia and Mycobacterium, require serine/threonine kinases for successful invasion of human host cells. The substrates targeted by bacterial serine/threonine kinases have remained largely unknown. Here we report that the serine/threonine kinase PknB from the important pathogen Staphylococcus aureus is released into the external milieu, which opens up the possibility that PknB does not only phosphorylate bacterial proteins but also proteins of the human host. To identify possible human targets of purified PknB, we studied in vitro phosphorylation of peptide microarrays and detected 68 possible human targets for phosphorylation. These results show that PknB is a proline-directed kinase with MAP kinase-like enzymatic activity. As the potential cellular targets for PknB are involved in apoptosis, immune responses, transport, and metabolism, PknB secretion may help the bacterium to evade intracellular killing and facilitate its growth. In apparent agreement with this notion, phosphorylation of the host-cell response coordinating transcription factor ATF-2 by PknB was confirmed by mass spectrometry. Taken together, our results identify PknB as the first prokaryotic representative of the proline-directed kinase/MAP kinase family of enzymes.
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Wiebe MS, Nichols RJ, Molitor TP, Lindgren JK, Traktman P. Mice deficient in the serine/threonine protein kinase VRK1 are infertile due to a progressive loss of spermatogonia. Biol Reprod 2009; 82:182-93. [PMID: 19696012 DOI: 10.1095/biolreprod.109.079095] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The VRK1 protein kinase has been implicated as a pro-proliferative factor. Genetic analyses of mutant alleles of the Drosophila and Caenorhabditis elegans VRK1 homologs have revealed phenotypes ranging from embryonic lethality to mitotic and meiotic defects with resultant sterility. Herein, we describe the first genetic analysis of murine VRK1. Two lines of mice containing distinct gene-trap integrations into the Vrk1 locus were established. Insertion into intron 12 (GT12) spared VRK1 function, enabling the examination of VRK1 expression in situ. Insertion into intron 3 (GT3) disrupted VRK1 function, but incomplete splicing to the gene trap rendered this allele hypomorphic (approximately 15% of wild-type levels of VRK1 remain). GT3/GT3 mice are viable, but both males and females are infertile. In testes, VRK1 is expressed in Sertoli cells and spermatogonia. The infertility of GT3/GT3 male mice results from a progressive defect in spermatogonial proliferation or differentiation, culminating in the absence of mitotic and meiotic cells in adult testis. These data demonstrate an important role for VRK1 in cell proliferation and confirm that the need for VRK1 during gametogenesis is evolutionarily conserved.
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Affiliation(s)
- Matthew S Wiebe
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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Scheeff ED, Eswaran J, Bunkoczi G, Knapp S, Manning G. Structure of the pseudokinase VRK3 reveals a degraded catalytic site, a highly conserved kinase fold, and a putative regulatory binding site. Structure 2009; 17:128-38. [PMID: 19141289 PMCID: PMC2639636 DOI: 10.1016/j.str.2008.10.018] [Citation(s) in RCA: 142] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 10/15/2008] [Accepted: 10/21/2008] [Indexed: 01/19/2023]
Abstract
About 10% of all protein kinases are predicted to be enzymatically inactive pseudokinases, but the structural details of kinase inactivation have remained unclear. We present the first structure of a pseudokinase, VRK3, and that of its closest active relative, VRK2. Profound changes to the active site region underlie the loss of catalytic activity, and VRK3 cannot bind ATP because of residue substitutions in the binding pocket. However, VRK3 still shares striking structural similarity with VRK2, and appears to be locked in a pseudoactive conformation. VRK3 also conserves residue interactions that are surprising in the absence of enzymatic function; these appear to play important architectural roles required for the residual functions of VRK3. Remarkably, VRK3 has an "inverted" pattern of sequence conservation: although the active site is poorly conserved, portions of the molecular surface show very high conservation, suggesting that they form key interactions that explain the evolutionary retention of VRK3.
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Affiliation(s)
- Eric D Scheeff
- Razavi Newman Center for Bioinformatics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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Sanz-García M, López-Sánchez I, Lazo PA. Proteomics identification of nuclear Ran GTPase as an inhibitor of human VRK1 and VRK2 (vaccinia-related kinase) activities. Mol Cell Proteomics 2008; 7:2199-214. [PMID: 18617507 PMCID: PMC2577208 DOI: 10.1074/mcp.m700586-mcp200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Human vaccinia-related kinase (VRK) 1 is a novel serine-threonine kinase that regulates several transcription factors, nuclear envelope assembly, and chromatin condensation and is also required for cell cycle progression. The regulation of this kinase family is unknown. Mass spectrometry has permitted the identification of Ran as an interacting and regulatory protein of the VRK serine-threonine kinase activities. The stable interaction has been validated by pulldown of endogenous proteins as well as by reciprocal immunoprecipitations. The three members of the VRK family stably interact with Ran, and the interaction was not affected by the bound nucleotide, GDP or GTP. The interaction was stronger with the RanT24N that is locked in its inactive conformation and cannot bind nucleotides. None of the kinases phosphorylated Ran or RCC1. VRK1 does not directly interact with RCC1, but if Ran is present they can be isolated as a complex. The main effect of the interaction of inactive RanGDP with VRK1 is the inhibition of its kinase activity, which was detected by a reduction in VRK1 autophosphorylation and a reduction in phosphorylation of histone H3 in residues Thr-3 and Ser-10. The kinase activity inhibition can be relieved by the interaction with the constitutively active RanGTP or RanL43E, which locks Ran in its GTP-bound active conformation. In this complex, the interaction with VRK proteins does not alter the effect of its guanine exchange factor, RCC1. Ran is a novel negative regulator of nuclear VRK1 and VRK2 kinase activity, which may vary in different subcellular localizations generating an asymmetric intracellular distribution of kinase activity depending on local protein interactions.
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Affiliation(s)
- Marta Sanz-García
- Programa de Oncología Translacional, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, Campus Miguel de Unamuno, Salamanca E-37007, Spain
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The C/H3 domain of p300 is required to protect VRK1 and VRK2 from their downregulation induced by p53. PLoS One 2008; 3:e2649. [PMID: 18612383 PMCID: PMC2441436 DOI: 10.1371/journal.pone.0002649] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Accepted: 06/09/2008] [Indexed: 12/29/2022] Open
Abstract
Background The vaccinia-related kinase 1 (VRK1) protein, an activator of p53, can be proteolytically downregulated by an indirect mechanism, which requires p53-dependent transcription. Principal Findings In this work we have biochemically characterized the contribution of several p53 transcriptional cofactors with acetyl transferase activity to the induction of VRK1 downregulation that was used as a functional assay. Downregulation of VRK1 induced by p53 is prevented in a dose dependent manner by either p300 or CBP, but not by PCAF, used as transcriptional co-activators, suggesting that p53 has a different specificity depending on the relative level of these transcriptional cofactors. This inhibition does not require p53 acetylation, since a p53 acetylation mutant also induces VRK1 downregulation. PCAF can not revert the VRK1 protection effect of p300, indicating that these two proteins do not compete for a common factor needed to induce VRK1 downregulation. The protective effect is also induced by the C/H3 domain of p300, a region implicated in binding to several transcription factors and SV40 large T antigen; but the protective effect is lost when a mutant C/H3Del33 is used. The protective effect is a consequence of direct binding of the C/H3 domain to the transactivation domain of p53. A similar downregulatory effect can also be detected with VRK2 protein. Conclusions/Significance Specific p53-dependent effects are determined by the availability and ratios of its transcriptional cofactors. Specifically, the downregulation of VRK1/VRK2 protein levels, as a consequence of p53 accumulation, is thus dependent on the levels of the p300/CBP protein available for transcriptional complexes, since in this context this cofactor functions as a repressor of the effect. These observations point to the relevance of knowing the cofactor levels in order to determine one effect or another.
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Valbuena A, López-Sánchez I, Lazo PA. Human VRK1 is an early response gene and its loss causes a block in cell cycle progression. PLoS One 2008; 3:e1642. [PMID: 18286197 PMCID: PMC2241669 DOI: 10.1371/journal.pone.0001642] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Accepted: 01/24/2008] [Indexed: 12/19/2022] Open
Abstract
Background In mammalian cells regulatory proteins controlling the cell cycle are necessary due to the requirements of living in a heterogeneous environment of cell-interactions and growth factors. VRK1 is a novel serine-threonine kinase that phosphorylates several transcription factors and is associated with proliferation phenotypes. Methodology/Principal Findings In this report VRK1 has been identified as regulated in the cell cycle. VRK1 gene expression is activated by the addition of serum to starved cells, indicating it is required for the exit of G0 phase and entry in G1; a response that parallels the re-expression of MYC, FOS and CCND1 (cyclin D1) genes, suggesting that VRK1 is an early-response gene. VRK1 gene expression is also shutdown by serum withdrawal. The human VRK1 gene promoter cloned in a luciferase reporter responds similarly to serum. In response to serum, the level of VRK1 protein expression has a positive correlation with cell proliferation markers such as phosphorylated-Rb or PCNA, and is inversely correlated with cell cycle inhibitors such as p27. The elimination of VRK1 by siRNA results in a G1 block in cell division, and in loss of phosphorylated-Rb, cyclin D1, and other proliferation markers. Elimination of VRK1 by siRNA induces a reduction of cell proliferation. VRK1 colocalizes with p63 in proliferating areas of squamous epithelium, and identifies a subpopulation in the basal layer. Conclusions/Significance VRK1 is an immediate early response gene required for entry in G1, and due to its implication in normal cell proliferation and division, might be a new target for development of inhibitors of cellular proliferation.
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Affiliation(s)
- Alberto Valbuena
- Programa de Oncología Translacional, Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer (CIC), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Salamanca, Spain
| | - Inmaculada López-Sánchez
- Programa de Oncología Translacional, Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer (CIC), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Salamanca, Spain
| | - Pedro A. Lazo
- Programa de Oncología Translacional, Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer (CIC), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Salamanca, Spain
- *E-mail:
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32
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Kang TH, Kim KT. VRK3-mediated inactivation of ERK signaling in adult and embryonic rodent tissues. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1783:49-58. [PMID: 18035061 DOI: 10.1016/j.bbamcr.2007.10.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 10/11/2007] [Accepted: 10/22/2007] [Indexed: 12/15/2022]
Abstract
Vaccinia-related kinase 3 (VRK3), previously characterized as a direct activator of vaccinia H1-related (VHR) phosphatase, inactivates extracellular signal-regulated kinase (ERK) in the nucleus of neuronal cells. Here we show that VRK3 is expressed in various other rodent tissues and in embryos, and regulates VHR phosphatase activity in these tissues. We observed colocalization of VRK3 and VHR in the testis tissue and could detect protein complex containing VRK3, VHR and ERK in immunoprecipitation analysis. Notably, the addition of recombinant VRK3 protein to total protein lysates, obtained either from adult tissues or embryos, enhanced the phosphatase activity of VHR, but not the activity of MKP3. The results further indicate that the VHR-VRK3 complex is a phosphatase-active form. In addition, we found that VRK3 can regulate EGF-induced cellular growth signaling that is mediated by ERK activation. Our results suggest that in addition to neuronal cells, various other rodent adult tissues and embryos possess a common signaling mechanism which is involved in an indirect regulation of ERK activity by VRK3-mediated VHR activity.
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Affiliation(s)
- Tae-Hong Kang
- Department of Life Science, Biotechnology Research Center, Division of Molecular and Life Science, Pohang University of Science and Technology (POSTECH), San-31, Hyoja-Dong, Pohang, 790-784, Republic of Korea
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Valbuena A, Suárez-Gauthier A, López-Rios F, López-Encuentra A, Blanco S, Fernández PL, Sánchez-Céspedes M, Lazo PA. Alteration of the VRK1-p53 autoregulatory loop in human lung carcinomas. Lung Cancer 2007; 58:303-9. [PMID: 17689819 DOI: 10.1016/j.lungcan.2007.06.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 06/21/2007] [Accepted: 06/25/2007] [Indexed: 11/26/2022]
Abstract
Human VRK1 (vaccinia-related kinase 1) is a novel serine-threonine kinase that regulates several transcription factors, including p53, ATF2 and c-Jun; and its loss results in defects of cell proliferation. VRK1 stabilizes p53 and the accumulated p53 downregulates VRK1 forming an autoregulatory loop. Wild-type p53, but not mutant p53, was able to downregulate VRK1 in the A549 lung carcinoma cell line. VRK1 expression has been studied in human lung carcinomas. VRK1 protein level was significantly higher in squamous cell lung carcinomas than in adenocarcinomas, and inversely correlated with p16. Tumours with p53 mutations have a positive trend with those having very high levels of VRK1 protein, particularly in squamous cell lung carcinomas. These data indicate that the VRK1-p53 autoregulatory loop was not functional in a group of lung carcinomas. The accumulation of VRK1 in tumours with mutant p53 could result in stimulation of other signalling pathways that can contribute to tumour growth and progression in addition to those resulting from loss of p53 function.
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Affiliation(s)
- Alberto Valbuena
- Programa de Oncología Translacional, Instituto de Biología Molecular y Celular del Cáncer, CSIC, Universidad de Salamanca, Spain
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Valbuena A, López-Sánchez I, Vega FM, Sevilla A, Sanz-García M, Blanco S, Lazo PA. Identification of a dominant epitope in human vaccinia-related kinase 1 (VRK1) and detection of different intracellular subpopulations. Arch Biochem Biophys 2007; 465:219-26. [PMID: 17617371 DOI: 10.1016/j.abb.2007.06.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 05/18/2007] [Accepted: 06/07/2007] [Indexed: 01/19/2023]
Abstract
The human VRK1 is a new ser-thr kinase expressed in many cell types. VRK1 is a regulator of p53 and other transcription factors related with cellular responses to stress. The human VRK1 protein has a dominant epitope located in its C-terminal region, between residues 333 and 396, which is detected by different antibodies. All the antibodies detect the same protein in immunoblots and immunoprecipitations. But the antibodies have a different reactivity when a single aminoacid substitution in T355, mimicking phosphorylation, is introduced next to the nuclear localization signal. These differences in reactivity permit the identification of different intracellular subpopulations. Most of the intracellular VRK1 protein is nuclear, but in some cells it is also detected in the cytosol, depending on the type of tissue. These different locations are detected by immunohistochemistry of human biopsies and immunofluorescence of cell lines. Some antibodies identify a subpopulation within the vesicular system, particularly in the Golgi apparatus. The different reactivity of the VRK1 protein indicates that this protein has a subcellular localization that can be regulated, thus adding an additional level of regulatory complexity to the VRK1 protein.
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Affiliation(s)
- Alberto Valbuena
- Programa de Oncología Translacional, Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, CSIC-Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain
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35
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Li LY, Liu MY, Shih HM, Tsai CH, Chen JY. Human cellular protein VRK2 interacts specifically with Epstein-Barr virus BHRF1, a homologue of Bcl-2, and enhances cell survival. J Gen Virol 2006; 87:2869-2878. [PMID: 16963744 DOI: 10.1099/vir.0.81953-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BHRF1, an early gene product of Epstein-Barr virus (EBV), is structurally and functionally homologous to Bcl-2, a cellular anti-apoptotic protein. BHRF1 has been shown to protect cells from apoptosis induced by numerous external stimuli. Nasopharyngeal carcinoma is an epithelial cancer associated closely with EBV infection. Specific proteins that might interact with and modulate the BHRF1 anti-apoptotic activity in normal epithelial cells are of interest. Therefore, a cDNA library derived from normal human foreskin keratinocytes was screened by the yeast two-hybrid system and a cellular gene encoding human vaccinia virus B1R kinase-related kinase 2 (VRK2) was isolated. Interaction between the cellular VRK2 and viral BHRF1 proteins was further demonstrated by glutathione S-transferase pull-down assays, confocal laser-scanning microscopy and co-immunoprecipitation. Analyses of VRK2-deletion mutants revealed that a 108 aa fragment at the C terminus was important for VRK2 to interact with BHRF1. For BHRF1, aa 1-18 and 89-142 were crucial in interacting with VRK2 and these two regions are counterparts of Bcl-2 homology domains 4 and 1. Overexpressed VRK2 alone showed a modest effect in anti-apoptosis and appeared to enhance cell survival in the presence of BHRF1. However, this enhancement was not observed when VRK2 was co-expressed with Bcl-2. The results indicate that human VRK2 interacts specifically with EBV BHRF1 and that the interaction is involved in protecting cells from apoptosis.
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Affiliation(s)
- Long-Yuan Li
- Institute of Cancer Research, National Health Research Institutes, Taipei 114, Taiwan
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Mei-Ying Liu
- Department of General Education, National Taipei College of Nursing, Taipei 112, Taiwan
- Institute of Cancer Research, National Health Research Institutes, Taipei 114, Taiwan
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Hsiu-Ming Shih
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Taipei 115, Taiwan
| | - Ching-Hwa Tsai
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Jen-Yang Chen
- Institute of Cancer Research, National Health Research Institutes, Taipei 114, Taiwan
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
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Blanco S, Klimcakova L, Vega FM, Lazo PA. The subcellular localization of vaccinia-related kinase-2 (VRK2) isoforms determines their different effect on p53 stability in tumour cell lines. FEBS J 2006; 273:2487-504. [PMID: 16704422 DOI: 10.1111/j.1742-4658.2006.05256.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
VRK is a new kinase family of unknown function. Endogenous human vacinia-related kinase 2 (VRK2) protein is present in both the nucleus and the cytosol, which is a consequence of alternative splicing of two VRK2 messages coding for proteins of 508 and 397 amino acids, respectively. VRK2A has a C-terminal hydrophobic region that anchors the protein to membranes in the endoplasmic reticulum (ER) and mitochondria, and it colocalizes with calreticulin, calnexin and mitotracker; whereas VRK2B is detected in both the cytoplasm and the nucleus. VRK2A is expressed in all cell types, whereas VRK2B is expressed in cell lines in which VRK1 is cytoplasmic. Both VRK2 isoforms have an identical catalytic N-terminal domain and phosphorylate p53 in vitro uniquely in Thr18. Phosphorylation of the p53 protein in response to cellular stresses results in its stabilization by modulating its binding to other proteins. However, p53 phosphorylation also occurs in the absence of stress. Only overexpression of the nuclear VRK2B isoform induces p53 stabilization by post-translational modification, largely due to Thr18 phosphorylation. VRK2B may play a role in controlling the binding specificity of the N-terminal transactivation domain of p53. Indeed, the p53 phosphorylated by VRK2B shows a reduction in ubiquitination by Mdm2 and an increase in acetylation by p300. Endogenous p53 is also phosphorylated in Thr18 by VRK2B, promoting its stabilization and transcriptional activation in A549 cells. The relative phosphorylation of Thr18 by VRK2B is similar in magnitude to that induced by taxol, which might use a different signalling pathway. In this context, VRK2B kinase might functionally replace nuclear VRK1. Therefore, these kinases might be components of a new signalling pathway that is likely to play a role in normal cell proliferation.
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Affiliation(s)
- Sandra Blanco
- Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Spain
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37
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Kang TH, Kim KT. Negative regulation of ERK activity by VRK3-mediated activation of VHR phosphatase. Nat Cell Biol 2006; 8:863-9. [PMID: 16845380 DOI: 10.1038/ncb1447] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Accepted: 05/30/2006] [Indexed: 11/08/2022]
Abstract
Extracellular signal regulated kinases (ERKs) represent a signalling hub in many physiological responses and have pivotal functions in cell proliferation, differentiation, development and death, as well as in synaptic plasticity. Mitogen-activated protein kinase phosphatases (MKPs) selectively inactivate ERKs by dephosphorylating critical phosphothreonine and phosphotyrosine residues. Transcriptional induction of MKP expression and posttranscriptional stabilization of MKP mRNA are well-documented as negative-feedback mechanisms for ERK signalling. Vaccinia-related kinase 3 (VRK3) is a member of the novel VRK family, but its function has not been defined. Here, we show that VRK3 suppresses ERK activity through direct binding to one of the MKPs, vaccinia H1-related (VHR), which specifically dephosphorylates and inactivates ERK in the nucleus. Notably, VRK3 enhances the phosphatase activity of VHR by a mechanism independent of its kinase activity. VRK3 is therefore a member of a new class of phosphatase-activating kinases that regulate the activity of ERK. Our findings show that direct interaction of VHR with VRK3 posttranslationally regulates ERK signalling.
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Affiliation(s)
- Tae-Hong Kang
- Department of Life Science, Biotechnology Research Center, Division of Molecular and Life Science, Pohang University of Science and Technology (POSTECH), San-31, Hyoja-Dong, Pohang, 790-784, Republic of Korea
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Santos CR, Rodríguez-Pinilla M, Vega FM, Rodríguez-Peralto JL, Blanco S, Sevilla A, Valbuena A, Hernández T, van Wijnen AJ, Li F, de Alava E, Sánchez-Céspedes M, Lazo PA. VRK1 signaling pathway in the context of the proliferation phenotype in head and neck squamous cell carcinoma. Mol Cancer Res 2006; 4:177-85. [PMID: 16547155 DOI: 10.1158/1541-7786.mcr-05-0212] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The vaccinia-related kinase (VRK) proteins are a new family with three members in the human kinome. The VRK1 protein phosphorylates several transcription factors and has been postulated to be involved in regulation of cell proliferation. In normal squamous epithelium, VRK1 is expressed in the proliferation area. Because VRK1 can stabilize p53, the expression of the VRK1 protein was analyzed in the context of the p53 pathway and the proliferation phenotype in a series of 73 head and neck squamous cell carcinomas. VRK1 protein level positively correlated with p53 response proteins, particularly hdm2 and p21. The VRK1 protein also correlated positively with several proteins associated with proliferation, such as cyclin-dependent kinase 2 (CDK2), CDK6, cdc2, cyclins B1 and A, topoisomerase II, survivin, and Ki67. The level of VRK1 protein behaves like a proliferation marker in this series of head and neck squamous cell carcinomas. To identify a possible regulatory role for VRK1 and because it regulates gene transcription, the promoters of two genes were studied, CDK2 and SURVIVIN, whose proteins correlated positively with VRK1. VRK1 increases the activity of both the CDK2 and SURVIVIN gene promoters. The expression of VRK1 was analyzed in the context of regulators of the G1-S transition. VRK1 protein levels increase in response to E2F1 and are reduced by retinoblastoma and p16. These data suggest that VRK1 might play a role in cell cycle regulation and is likely to represent the beginning of a new control mechanism of cell cycle, particularly late in the G1-S phase.
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Affiliation(s)
- Claudio R Santos
- Instituto de Biología Molecular y Celular del Cáncer, Centro de Investigación del Cáncer, Consejo Superior de Investigaciones Cientificas, Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain
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Vega FM, Sevilla A, Lazo PA. p53 Stabilization and accumulation induced by human vaccinia-related kinase 1. Mol Cell Biol 2005; 24:10366-80. [PMID: 15542844 PMCID: PMC529057 DOI: 10.1128/mcb.24.23.10366-10380.2004] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Variations in intracellular levels of p53 regulate many cellular functions and determine tumor susceptibility. Major mechanisms modulating p53 levels include phosphorylation and interaction of p53 with specific ubiquitin ligases that promote its degradation. N-terminal phosphorylation regulates the interaction of p53 with several regulatory molecules. Vaccinia-related kinase 1 (VRK1) is the prototype of a new Ser-Thr kinase family in the human kinome. VRK1 is located in the nucleus outside the nucleolus. Overexpression of VRK1 increases the stability of p53 by a posttranslational mechanism leading to its accumulation by a mechanism independent of the Chk2 kinase. Catalytically inactive VRK1 protein (a K179E mutant) does not induce p53 accumulation. VRK1 phosphorylates human p53 in Thr18 and disrupts p53-Mdm2 interaction in vitro, although a significant decrease in p53 ubiquitination by Mdm2 in vivo was not detected. VRK1 kinase does not phosphorylate Mdm2. VRK1-mediated p53 stabilization was also detected in Mdm2(-/-) cells. VRK1 also has an additive effect with MdmX or p300 to stabilize p53, and p300 coactivation and acetylation of p53 is enhanced by VRK1. The p53 stabilized by VRK1 is transcriptionally active. Suppression of VRK1 expression by specific small interfering RNA provokes several defects in proliferation, situating the protein in the regulation of this process. VRK1 might function as a switch controlling the proteins that interact with p53 and thus modifying its stability and activity. We propose VRK1 as the first step in a new pathway regulating p53 activity during cell proliferation.
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Affiliation(s)
- Francisco M Vega
- Centro de Investigación del Cáncer, C.S.I.C.-Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain
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Sevilla A, Santos CR, Barcia R, Vega FM, Lazo PA. c-Jun phosphorylation by the human vaccinia-related kinase 1 (VRK1) and its cooperation with the N-terminal kinase of c-Jun (JNK). Oncogene 2004; 23:8950-8. [PMID: 15378002 DOI: 10.1038/sj.onc.1208015] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The VRK1 kinase is a novel Ser-Thr kinase in the human kinome that diverged from the casein kinase 1 branch. These kinases phosphorylate transcription factors related to stress responses, such as p53. In this report we have studied the phosphorylation of the transcription factor c-Jun in its N-terminal region. The VRK1 protein phosphorylates c-Jun with a Km of 0.4 muM, and is not inhibited by SP600125. VRK1 phosphorylates c-Jun in Ser63 and Ser73 in vitro, the same residues targeted by the N-terminal kinase of c-Jun (JNK). This phosphorylation induces the stabilization and accumulation of the c-Jun protein. VRK1 phosphorylates the endogenous c-Jun in Ser63. VRK1 activates c-Jun dependent transcription, which is dependent on phosphorylation of Ser63 and Ser73. The c-Jun with Ser63Ala and Ser73Ala substitutions is not transcriptionally active when cotransfected with VRK1. VRK1 interacts with c-Jun but not with JNK. The cotransfection of VRK1 and JNK has an additive effect on the transcriptional activation of c-Jun indicating that they can cooperate when both are at suboptimal dose; otherwise, maximum effect by one of them prevents the effect of the other. The VRK1-c-Jun connection represents a component of a new signaling pathway whose upstream elements remain to be identified.
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Affiliation(s)
- Ana Sevilla
- Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain
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Sevilla A, Santos CR, Vega FM, Lazo PA. Human vaccinia-related kinase 1 (VRK1) activates the ATF2 transcriptional activity by novel phosphorylation on Thr-73 and Ser-62 and cooperates with JNK. J Biol Chem 2004; 279:27458-65. [PMID: 15105425 DOI: 10.1074/jbc.m401009200] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the human kinome, vaccinia-related kinase-1 (VRK1) is a new Ser-Thr kinase associated with proliferating tissues. VRK1 colocalizes with ATF2 in the nucleus and can form a stable complex. We have studied the phosphorylation of the transcription factor ATF2, which regulates gene expression by forming dimers with proteins with basic region-leucine zipper domains and recognizing cAMP-response element or AP1 sequences implicated in cellular responses to stress. VRK1 phosphorylates ATF2 mainly on Thr-73, stabilizing the ATF2 protein and increasing its intracellular level. Mutagenesis studies showed that Thr-73 and Ser-62 are implicated in ATF2 transcriptional activation by VRK1 detected in a functional assay based on ATF2 dimerization. VRK1 can activate the collagenase gene promoter that is regulated by ATF2 in a dose-dependent manner. Loss of kinase activity (K179E mutant) or the T73A substitution in ATF2 prevents both its accumulation and activation of transcription. VRK1 and JNK, which phosphorylates ATF2 in Thr-69 and Thr-71, have an additive effect on ATF2-dependent transcription at suboptimal doses. Therefore, two groups of amino acids in the ATF2 amino-terminal region can integrate different cellular signals mediated by at least five different kinases. VRK1 is an element of a novel signaling pathway that regulates gene transcription.
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Affiliation(s)
- Ana Sevilla
- Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain
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Boyle KA, Traktman P. Members of a novel family of mammalian protein kinases complement the DNA-negative phenotype of a vaccinia virus ts mutant defective in the B1 kinase. J Virol 2004; 78:1992-2005. [PMID: 14747564 PMCID: PMC369515 DOI: 10.1128/jvi.78.4.1992-2005.2004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Temperature-sensitive (ts) mutants of vaccinia virus defective in the B1 kinase demonstrate a conditionally lethal defect in DNA synthesis. B1 is the prototypic member of a new family of protein kinases (vaccinia virus-related kinases, or VRK) that possess distinctive B1-like sequence features within their catalytic motifs (R. J. Nichols and P. Traktman, J. Biol. Chem., in press). Given the striking sequence similarity between B1 and the VRK enzymes, we proposed that they might share overlapping substrate specificity. We therefore sought to determine whether the human and mouse VRK1 enzymes (hVRK1 and mVRK1, respectively) could complement a B1 deficiency in vivo. Recombinant ts2 viruses expressing hVRK1, mVRK1, or wild-type B1 were able to synthesize viral DNA at high temperature, but those expressing the more distantly related human casein kinase 1 alpha 2 could not. Complementation required the enzymatic activity of hVRK1, since a catalytically inactive allele of hVRK1 was unable to confer a temperature-insensitive phenotype. Interestingly, rescue of viral DNA synthesis was not coupled to the ability to phosphorylate H5, the only virus-encoded protein shown to be a B1 substrate in vivo. Expression of hVRK1 during nonpermissive ts2 infections restored virus production and plaque formation, whereas expression of mVRK1 resulted in an intermediate level of rescue. Taken together, these observations indicate that enzymatically active cellular VRK1 kinases can perform the function(s) of B1 required for genome replication, most likely due to overlapping specificity for cellular and/or viral substrates.
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Affiliation(s)
- Kathleen A Boyle
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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Nichols RJ, Traktman P. Characterization of three paralogous members of the Mammalian vaccinia related kinase family. J Biol Chem 2003; 279:7934-46. [PMID: 14645249 DOI: 10.1074/jbc.m310813200] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the novel vaccinia related kinase (VRK) protein family are characterized by notable sequence homology to the vaccinia virus-encoded B1 kinase (vvB1). vvB1 plays an essential role in viral DNA replication, and Boyle and Traktman have demonstrated that VRK1 enzymes complement the replication defect of a temperature-sensitive viral mutant defective in vvB1 (Boyle, K., and Traktman, P. (2004) J. Virol. 78, 1992-2005). This mammalian kinase family comprises three members, VRK1, VRK2, and VRK3. We have annotated the gene structure for the members of this family and have characterized the enzyme activity and subcellular localization for the human and mouse proteins. VRK1 enzymes show robust autophosphorylation activity and will phosphorylate casein; VRK2 enzymes show modest autophosphorylation activity and will also phosphorylate casein. The VRK3 proteins have key amino acid substitutions that disrupt invariant motifs required for catalytic activity, rendering them enzymatically inert. The VRK1 and VRK2 proteins contain COOH-terminal extracatalytic sequences that mediate intracellular localization. VRK1 proteins possess a basic nuclear localization signal and are indeed nuclear; the extreme C termini of the VRK2 proteins are highly hydrophobic, and the proteins are membrane-associated and colocalize with markers of the endoplasmic reticulum. The NH(2)-terminal region of the VRK3s contains a bipartite nuclear localization signal, which directs these proteins to the nucleus. Our findings provide the basis for further studies of the structure and function of this newly discovered family of protein kinases.
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Affiliation(s)
- R Jeremy Nichols
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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