1
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Chen W, Zhu L, Wang L, Zeng J, Wen M, Xu X, Zou L, Huang F, Huang Q, Qin D, Mei Q, Yang J, Wang Q, Wu J. A Novel Antithrombocytopenia Agent, Rhizoma cibotii, Promotes Megakaryopoiesis and Thrombopoiesis through the PI3K/AKT, MEK/ERK, and JAK2/STAT3 Signaling Pathways. Int J Mol Sci 2022; 23:ijms232214060. [PMID: 36430539 PMCID: PMC9694118 DOI: 10.3390/ijms232214060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Cibotii rhizoma (CR) is a famous traditional Chinese medicine (TCM) used to treat bleeding, rheumatism, lumbago, etc. However, its therapeutic effects and mechanism against thrombocytopenia are still unknown so far. In the study, we investigated the effects of aqueous extracts of Cibotii rhizoma (AECRs) against thrombocytopenia and its molecular mechanism. METHODS Giemsa staining, phalloidin staining, and flow cytometry were performed to measure the effect of AECRs on the megakaryocyte differentiation in K562 and Meg-01 cells. A radiation-induced thrombocytopenia mouse model was constructed to assess the therapeutic actions of AECRs on thrombocytopenia. Network pharmacology and experimental verification were carried out to clarify its mechanism against thrombocytopenia. RESULTS AECRs promoted megakaryocyte differentiation in K562 and Meg-01 cells and accelerated platelet recovery and megakaryopoiesis with no systemic toxicity in radiation-induced thrombocytopenia mice. The PI3K/AKT, MEK/ERK, and JAK2/STAT3 signaling pathways contributed to AECR-induced megakaryocyte differentiation. The suppression of the above signaling pathways by their inhibitors blocked AERC-induced megakaryocyte differentiation. CONCLUSIONS AECRs can promote megakaryopoiesis and thrombopoiesis through activating PI3K/AKT, MEK/ERK, and JAK2/STAT3 signaling pathways, which has the potential to treat radiation-induced thrombocytopenia in the clinic.
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Affiliation(s)
- Wang Chen
- School of Pharmacy, Southwest Medical University, Luzhou 646000, China
| | - Linjie Zhu
- School of Pharmacy, Southwest Medical University, Luzhou 646000, China
| | - Long Wang
- School of Pharmacy, Southwest Medical University, Luzhou 646000, China
| | - Jing Zeng
- School of Pharmacy, Southwest Medical University, Luzhou 646000, China
| | - Min Wen
- School of Pharmacy, Southwest Medical University, Luzhou 646000, China
| | - Xiyan Xu
- School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, China
| | - LiLe Zou
- School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, China
| | - Feihong Huang
- School of Pharmacy, Southwest Medical University, Luzhou 646000, China
| | - Qianqian Huang
- School of Pharmacy, Southwest Medical University, Luzhou 646000, China
| | - Dalian Qin
- School of Pharmacy, Southwest Medical University, Luzhou 646000, China
- Education Ministry Key Laboratory of Medical Electrophysiology, Southwest Medical University, Luzhou 646000, China
| | - Qibing Mei
- School of Pharmacy, Southwest Medical University, Luzhou 646000, China
- Education Ministry Key Laboratory of Medical Electrophysiology, Southwest Medical University, Luzhou 646000, China
| | - Jing Yang
- School of Pharmacy, Southwest Medical University, Luzhou 646000, China
- Education Ministry Key Laboratory of Medical Electrophysiology, Southwest Medical University, Luzhou 646000, China
| | - Qiaozhi Wang
- School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, China
- Correspondence: (Q.W.); (J.W.); Tel.: 86-18015728611 (Q.W.); 86-13982416641 (J.W.)
| | - Jianming Wu
- School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, China
- Education Ministry Key Laboratory of Medical Electrophysiology, Southwest Medical University, Luzhou 646000, China
- Correspondence: (Q.W.); (J.W.); Tel.: 86-18015728611 (Q.W.); 86-13982416641 (J.W.)
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2
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Mohtashami M, Razavi A, Abolhassani H, Aghamohammadi A, Yazdani R. Primary Immunodeficiency and Thrombocytopenia. Int Rev Immunol 2021; 41:135-159. [PMID: 33464134 DOI: 10.1080/08830185.2020.1868454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Primary immunodeficiency (PID) or Inborn errors of immunity (IEI) refers to a heterogeneous group of disorders characterized by immune system impairment. Although patients with IEI manifest highly variable symptoms, the most common clinical manifestations are recurrent infections, autoimmunity and malignancies. Some patients present hematological abnormality including thrombocytopenia due to different pathogenic mechanisms. This review focuses on primary and secondary thrombocytopenia as a complication, which can occur in IEI. Based on the International Union of Immunological Societies phenotypic classification for IEI, the several innate and adaptive immunodeficiency disorders can lead to thrombocytopenia. This review, for the first time, describes manifestation, mechanism and therapeutic modalities for thrombocytopenia in different classes of IEI.
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Affiliation(s)
- Maryam Mohtashami
- Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran.,Research Center for Immunodeficiencies, Tehran University of Medical Sciences, Tehran, Iran
| | - Azadehsadat Razavi
- Research Center for Immunodeficiencies, Tehran University of Medical Sciences, Tehran, Iran.,Department of Animal Biology, Faculty of Biology Sciences, University of Kharazmi, Tehran, Iran.,Cancer Immunology Project (CIP), Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Hassan Abolhassani
- Research Center for Immunodeficiencies, Tehran University of Medical Sciences, Tehran, Iran.,Division of Clinical Immunology, Department of Laboratory Medicine, Karolinska Institute at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Asghar Aghamohammadi
- Research Center for Immunodeficiencies, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Yazdani
- Research Center for Immunodeficiencies, Tehran University of Medical Sciences, Tehran, Iran
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3
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Identification of Modulators of HIV-1 Proviral Transcription from a Library of FDA-Approved Pharmaceuticals. Viruses 2020; 12:v12101067. [PMID: 32977702 PMCID: PMC7598649 DOI: 10.3390/v12101067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 09/01/2020] [Accepted: 09/10/2020] [Indexed: 12/21/2022] Open
Abstract
Human immunodeficiency virus 1 (HIV-1) is the most prevalent human retrovirus. Recent data show that 34 million people are living with HIV-1 worldwide. HIV-1 infections can lead to AIDS which still causes nearly 20,000 deaths annually in the USA alone. As this retrovirus leads to high morbidity and mortality conditions, more effective therapeutic regimens must be developed to treat these viral infections. A key target for intervention for which there are no current FDA-approved modulators is at the point of proviral transcription. One successful method for identifying novel therapeutics for treating infectious diseases is the repurposing of pharmaceuticals that are approved by the FDA for alternate indications. Major benefits of using FDA-approved drugs include the fact that the compounds have well established toxicity profiles, approved manufacturing processes, and immediate commercial availability to the patients. Here, we demonstrate that pharmaceuticals previously approved for other indications can be utilized to either activate or inhibit HIV-1 proviral transcription. Specifically, we found febuxostat, eltrombopag, and resveratrol to be activators of HIV-1 transcription, while mycophenolate was our lead inhibitor of HIV-1 transcription. Additionally, we observed that the infected cells of lymphoid and myeloid lineage responded differently to our lead transcriptional modulators. Finally, we demonstrated that the use of a multi-dose regimen allowed for enhanced activation with our transcriptional activators.
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4
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Mussbacher M, Salzmann M, Brostjan C, Hoesel B, Schoergenhofer C, Datler H, Hohensinner P, Basílio J, Petzelbauer P, Assinger A, Schmid JA. Cell Type-Specific Roles of NF-κB Linking Inflammation and Thrombosis. Front Immunol 2019; 10:85. [PMID: 30778349 PMCID: PMC6369217 DOI: 10.3389/fimmu.2019.00085] [Citation(s) in RCA: 368] [Impact Index Per Article: 73.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 01/11/2019] [Indexed: 12/22/2022] Open
Abstract
The transcription factor NF-κB is a central mediator of inflammation with multiple links to thrombotic processes. In this review, we focus on the role of NF-κB signaling in cell types within the vasculature and the circulation that are involved in thrombo-inflammatory processes. All these cells express NF-κB, which mediates important functions in cellular interactions, cell survival and differentiation, as well as expression of cytokines, chemokines, and coagulation factors. Even platelets, as anucleated cells, contain NF-κB family members and their corresponding signaling molecules, which are involved in platelet activation, as well as secondary feedback circuits. The response of endothelial cells to inflammation and NF-κB activation is characterized by the induction of adhesion molecules promoting binding and transmigration of leukocytes, while simultaneously increasing their thrombogenic potential. Paracrine signaling from endothelial cells activates NF-κB in vascular smooth muscle cells and causes a phenotypic switch to a “synthetic” state associated with a decrease in contractile proteins. Monocytes react to inflammatory situations with enforced expression of tissue factor and after differentiation to macrophages with altered polarization. Neutrophils respond with an extension of their life span—and upon full activation they can expel their DNA thereby forming so-called neutrophil extracellular traps (NETs), which exert antibacterial functions, but also induce a strong coagulatory response. This may cause formation of microthrombi that are important for the immobilization of pathogens, a process designated as immunothrombosis. However, deregulation of the complex cellular links between inflammation and thrombosis by unrestrained NET formation or the loss of the endothelial layer due to mechanical rupture or erosion can result in rapid activation and aggregation of platelets and the manifestation of thrombo-inflammatory diseases. Sepsis is an important example of such a disorder caused by a dysregulated host response to infection finally leading to severe coagulopathies. NF-κB is critically involved in these pathophysiological processes as it induces both inflammatory and thrombotic responses.
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Affiliation(s)
- Marion Mussbacher
- Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria
| | - Manuel Salzmann
- Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria
| | - Christine Brostjan
- Department of Surgery, General Hospital, Medical University of Vienna, Vienna, Austria
| | - Bastian Hoesel
- Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria
| | | | - Hannes Datler
- Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria
| | - Philipp Hohensinner
- Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria
| | - José Basílio
- Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria
| | - Peter Petzelbauer
- Skin and Endothelial Research Division, Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Alice Assinger
- Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria
| | - Johannes A Schmid
- Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria
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5
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Zhao C, Zhao Q, Zhang C, Wang G, Yao Y, Huang X, Zhan F, Zhu Y, Shi J, Chen J, Yan F, Zhang Y. miR-15b-5p resensitizes colon cancer cells to 5-fluorouracil by promoting apoptosis via the NF-κB/XIAP axis. Sci Rep 2017. [PMID: 28646148 PMCID: PMC5482850 DOI: 10.1038/s41598-017-04172-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Drug resistance, which is closely correlated with an imbalance in apoptosis, endows colorectal cancer (CRC) with enhanced progression capacity irrespective of the treatment with therapeutics. We report that miR-15b-5p is a tumor suppressor whose level is globally decreased in CRC cells and tissues. Over-expression of miR-15b-5p not only promoted 5-fluorouracil (5-FU)-induced cellular apoptosis but also reversed the chemoresistance of 5-FU in vitro and in vivo. As a key mediator of inflammation-induced cancer, miR-15b-5p enhances these therapeutic effects are mainly attributed to targeting of the NF-κB signaling pathway through negative regulation of NF-κB1 and one of its kinase complexes IKK-α. miR-15b-5p mediates NF-ĸB regulation by targeting the anti-apoptosis protein XIAP in vitro. Together, these results establish an axis of miR-15b-mediated apoptosis regulation, which reverses chemoresistance and suppresses CRC progression. These findings suggest that miR-15b-5p may be a potential agent for CRC treatment, particularly for 5-FU-resistant CRC.
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Affiliation(s)
- Ci Zhao
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China.,Translation Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, 150000, China
| | - Qi Zhao
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China.,Translation Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, 150000, China
| | - Chunhui Zhang
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China
| | - Guangyu Wang
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China
| | - Yuanfei Yao
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China
| | - Xiaoyi Huang
- Translation Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, 150000, China.,Department of Biotherapy, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China
| | - Fei Zhan
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China
| | - Yuanyuan Zhu
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China
| | - Jiaqi Shi
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China
| | - Jianan Chen
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China
| | - Feihu Yan
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China
| | - Yanqiao Zhang
- Department of Gastrointestinal Medical Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin, 150000, China.
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6
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Mao G, Jin J, Kunapuli SP, Rao AK. Nuclear factor-κB regulates expression of platelet phospholipase C-β2 (PLCB2). Thromb Haemost 2016; 116:931-940. [PMID: 27465150 PMCID: PMC6919569 DOI: 10.1160/th15-09-0749] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 07/10/2016] [Indexed: 11/05/2022]
Abstract
Phospholipase C (PLC)-β2 (gene PLCB2) is a critical regulator of platelet responses upon activation. Mechanisms regulating of PLC-β2 expression in platelets/MKs are unknown. Our studies in a patient with platelet PLC-β2 deficiency revealed the PLCB2 coding sequence to be normal and decreased platelet PLC-β2 mRNA, suggesting a defect in transcriptional regulation. PLCB2 5'- upstream region of the patient revealed a heterozygous 13 bp deletion (-1645/-1633 bp) encompassing a consensus sequence for nuclear factor-κB (NF-κB). This was subsequently detected in three of 50 healthy subjects. To understand the mechanisms regulating PLC-β2, we studied the effect of this variation in the PLCB2. Gel-shift studies using nuclear extracts from human erythroleukaemia (HEL) cells or recombinant p65 showed NF-κB binding to oligonucleotide with NF-κB site; in luciferase reporter studies its deletion reduced PLCB2 promoter activity. PLCB2 expression was decreased by siRNA knockdown of NF-κB p65 subunit and increased by p65 overexpression. By immunoblotting platelet PLC-β2 in 17 healthy subjects correlated with p65 (r=0.76, p=0.0005). These studies provide the first evidence that NF-κB regulates MK/platelet PLC-β2 expression. This interaction is important because of the major role of PLC-β2 in platelet activation and of NF-κB in processes, including inflammation and atherosclerosis, where both are intimately involved.
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Affiliation(s)
| | | | | | - A Koneti Rao
- A. Koneti Rao, MD, Sol Sherry Thrombosis Research Center, Temple University School of Medicine, 3400 North Broad Street, MRB-204, Philadelphia, PA 19140, USA, Tel.: +1 215 707 4684, Fax: +1 215 707 2783, E-mail:
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7
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Hyaluronan Depolymerization by Megakaryocyte Hyaluronidase-2 Is Required for Thrombopoiesis. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:2390-403. [PMID: 27398974 DOI: 10.1016/j.ajpath.2016.05.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 04/19/2016] [Accepted: 05/10/2016] [Indexed: 12/14/2022]
Abstract
Hyaluronan is the predominant glycosaminoglycan component of the extracellular matrix with an emerging role in hematopoiesis. Modulation of hyaluronan polymer size is responsible for its control over cellular functions, and the balance of hyaluronan synthesis and degradation determines its molecular size. Although two active somatic hyaluronidases are expressed in mammals, only deficiency in hyaluronidase-2 (Hyal-2) results in thrombocytopenia of unknown mechanism. Our results reveal that Hyal-2 knockout mice accumulate hyaluronan within their bone marrow and within megakaryocytes, the cells responsible for platelet generation. Proplatelet formation by Hyal-2 knockout megakaryocytes was disrupted because of abnormal formation of the demarcation membrane system, which was dilated and poorly developed. Importantly, peptide-mediated delivery of exogenous hyaluronidase rescued deficient proplatelet formation in murine and human megakaryocytes lacking Hyal-2. Together, our data uncover a previously unsuspected mechanism of how hyaluronan and Hyal-2 control platelet generation.
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8
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Bethel M, Barnes CLT, Taylor AF, Cheng YH, Chitteti BR, Horowitz MC, Bruzzaniti A, Srour EF, Kacena MA. A novel role for thrombopoietin in regulating osteoclast development in humans and mice. J Cell Physiol 2015; 230:2142-51. [PMID: 25656774 DOI: 10.1002/jcp.24943] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 01/23/2015] [Indexed: 11/10/2022]
Abstract
Emerging data suggest that megakaryocytes (MKs) play a significant role in skeletal homeostasis. Indeed, osteosclerosis observed in several MK-related disorders may be a result of increased numbers of MKs. In support of this idea, we have previously demonstrated that MKs increase osteoblast (OB) proliferation by a direct cell-cell contact mechanism and that MKs also inhibit osteoclast (OC) formation. As MKs and OCs are derived from the same hematopoietic precursor, in these osteoclastogenesis studies we examined the role of the main MK growth factor, thrombopoietin (TPO) on OC formation and bone resorption. Here we show that TPO directly increases OC formation and differentiation in vitro. Specifically, we demonstrate the TPO receptor (c-mpl or CD110) is expressed on cells of the OC lineage, c-mpl is required for TPO to enhance OC formation in vitro, and TPO activates the mitogen-activated protein kinases, Janus kinase/signal transducer and activator of transcription, and nuclear factor-kappaB signaling pathways, but does not activate the PI3K/AKT pathway. Further, we found TPO enhances OC resorption in CD14+CD110+ human OC progenitors derived from peripheral blood mononuclear cells, and further separating OC progenitors based on CD110 expression enriches for mature OC development. The regulation of OCs by TPO highlights a novel therapeutic target for bone loss diseases and may be important to consider in the numerous hematologic disorders associated with alterations in TPO/c-mpl signaling as well as in patients suffering from bone disorders.
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Affiliation(s)
- Monique Bethel
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana
| | - Calvin L T Barnes
- Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut
| | - Amanda F Taylor
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana
| | - Ying-Hua Cheng
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana
| | | | - Mark C Horowitz
- Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut
| | - Angela Bruzzaniti
- Department of Oral Biology, Indiana University School of Dentistry, Indianapolis, Indiana.,Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Edward F Srour
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana.,Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana.,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Melissa A Kacena
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, Indiana.,Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut.,Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
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9
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Eisenstein A, Carroll SH, Johnston-Cox H, Farb M, Gokce N, Ravid K. An adenosine receptor-Krüppel-like factor 4 protein axis inhibits adipogenesis. J Biol Chem 2015; 289:21071-81. [PMID: 24928509 DOI: 10.1074/jbc.m114.566406] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Adipogenesis represents a key process in adipose tissue development and remodeling, including during obesity. Exploring the regulation of adipogenesis by extracellular ligands is fundamental to our understanding of this process. Adenosine, an extracellular nucleoside signaling molecule found in adipose tissue depots, acts on adenosine receptors. Here we report that, among these receptors, the A2b adenosine receptor (A2bAR) is highly expressed in adipocyte progenitors. Activation of the A2bAR potently inhibits differentiation of mouse stromal vascular cells into adipocytes, whereas A2bAR knockdown stimulates adipogenesis. The A2bAR inhibits differentiation through a novel signaling cascade involving sustained expression of Krüppel-like factor 4 (KLF4), a regulator of stem cell maintenance. Knockdown of KLF4 ablates the ability of the A2bAR to inhibit differentiation. A2bAR activation also inhibits adipogenesis in a human primary preadipocyte culture system. We analyzed the A2bARKLF4 axis in adipose tissue of obese subjects and, intriguingly, found a strong correlation between A2bAR and KLF4 expression in both subcutaneous and visceral human fat. Hence, our study implicates the A2bAR as a regulator of adipocyte differentiation and the A2bAR-KLF4 axis as a potentially significant modulator of adipose biology.
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10
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Thrombopoietin promotes NHEJ DNA repair in hematopoietic stem cells through specific activation of Erk and NF-κB pathways and their target, IEX-1. Blood 2013; 123:509-19. [PMID: 24184684 DOI: 10.1182/blood-2013-07-515874] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Loss of hematopoietic stem cell (HSC) function and increased risk of developing hematopoietic malignancies are severe and concerning complications of anticancer radiotherapy and chemotherapy. We have previously shown that thrombopoietin (TPO), a critical HSC regulator, ensures HSC chromosomal integrity and function in response to γ-irradiation by regulating their DNA-damage response. TPO directly affects the double-strand break (DSB) repair machinery through increased DNA-protein kinase (DNA-PK) phosphorylation and nonhomologous end-joining (NHEJ) repair efficiency and fidelity. This effect is not shared by other HSC growth factors, suggesting that TPO triggers a specific signal in HSCs facilitating DNA-PK activation upon DNA damage. The discovery of these unique signaling pathways will provide a means of enhancing TPO-desirable effects on HSCs and improving the safety of anticancer DNA agents. We show here that TPO specifically triggers Erk and nuclear factor κB (NF-κB) pathways in mouse hematopoietic stem and progenitor cells (HSPCs). Both of these pathways are required for a TPO-mediated increase in DSB repair. They cooperate to induce and activate the early stress-response gene, Iex-1 (ier3), upon DNA damage. Iex-1 forms a complex with pERK and the catalytic subunit of DNA-PK, which is necessary and sufficient to promote TPO-increased DNA-PK activation and NHEJ DSB repair in both mouse and human HSPCs.
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11
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Di Michele M, Peeters K, Loyen S, Thys C, Waelkens E, Overbergh L, Hoylaerts M, Van Geet C, Freson K. Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) impairs the regulation of apoptosis in megakaryocytes by activating NF-κB: a proteomic study. Mol Cell Proteomics 2011; 11:M111.007625. [PMID: 21972247 DOI: 10.1074/mcp.m111.007625] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We previously showed that the Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) and its receptor VPAC1 are negative regulators of megakaryopoiesis and platelet function, but their downstream signaling pathway that inhibits this process still remained unknown. A combined proteomic, transcriptomic, and bioinformatic approach was here used to elucidate the molecular mechanisms underlying PACAP signaling via VPAC1 in megakaryocytes. Two-dimensional difference gel electrophoresis and tandem MS were applied to detect differentially expressed proteins in megakaryocytic CHRF cells stimulated with PACAP. The majority of the 120 proteins modulated by PACAP belong to the class of "cell cycle and apoptosis" proteins. The up- or down-regulated expression of some proteins was confirmed by immunoblot and immunohistochemical analysis. A meta-analysis of our data and 12 other published studies was performed to evaluate signaling pathways involved in different cellular models of PACAP response. From 2384 differentially expressed genes/proteins, 83 were modulated by PACAP in at least three independent studies and Ingenuity Pathway Analysis further identified apoptosis as the highest scored network with NF-κB as a key-player. PACAP inhibited serum depletion-induced apoptosis of CHRF cells via VPAC1 stimulation. In addition, PACAP switched on NF-κB dependent gene expression since higher nuclear levels of the active NF-κB p50/p65 heterodimer were found in CHRF cells treated with PACAP. Finally, a quantitative real time PCR apoptosis array was used to study RNA from in vitro differentiated megakaryocytes from a PACAP overexpressing patient, leading to the identification of 15 apoptotic genes with a 4-fold change in expression and Ingenuity Pathway Analysis again revealed NF-κB as the central player. In conclusion, our findings suggest that PACAP interferes with the regulation of apoptosis in megakaryocytes, probably via stimulation of the NF-κB pathway.
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Affiliation(s)
| | - Karen Peeters
- Center for Molecular and Vascular Biology, Leuven, Belgium
| | - Serena Loyen
- Center for Molecular and Vascular Biology, Leuven, Belgium
| | - Chantel Thys
- Center for Molecular and Vascular Biology, Leuven, Belgium
| | | | - Lutgart Overbergh
- Laboratory for Experimental Medicine and Endocrinology, Leuven, Belgium
| | - Marc Hoylaerts
- Center for Molecular and Vascular Biology, Leuven, Belgium
| | - Christel Van Geet
- Center for Molecular and Vascular Biology, Leuven, Belgium; Department of Pediatrics, University Hospital Leuven, K.U. Leuven, Leuven, Belgium
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12
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Sahler J, Bernard JJ, Spinelli SL, Blumberg N, Phipps RP. The Feverfew plant-derived compound, parthenolide enhances platelet production and attenuates platelet activation through NF-κB inhibition. Thromb Res 2011; 127:426-34. [PMID: 21272923 DOI: 10.1016/j.thromres.2010.12.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 12/13/2010] [Accepted: 12/21/2010] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Few treatments are available that can safely and effectively stimulate new platelet production for thrombocytopenic patients. Additionally, recipients of transfused platelets may experience an inflammatory response due to stored platelets becoming unnecessarily activated, thus creating the need for suitable agents that will dampen undesirable platelet activation. We investigated the effect of the feverfew plant-derived compound, parthenolide on platelet production and platelet activation because of its well-studied ability to induce apoptosis or differentiation in some types of cancer. METHODS Parthenolide was used to treat human megakaryoblastic cell lines, primary human and mouse megakaryocytes. Resulting platelet production and function was measured via flow cytometry. The two most common parthenolide signaling mechanisms, oxidative stress and nuclear factor-κB inhibition, were assessed within the megakaryocytes using reactive oxygen species, glutathione and luciferase reporter assays. The influence of parthenolide on ex vivo platelet activation was tested with parthenolide pretreatment followed by collagen or thrombin activation. The resulting P-selectin surface expression and released soluble CD40 ligand was measured. RESULTS Parthenolide stimulates functional platelet production from human megakaryocyte cell lines, and from primary mouse and human megakaryocytes in vitro. Parthenolide enhances platelet production via inhibition of nuclear factor-κB signaling in megakaryocytes and is independent of the parthenolide-induced oxidative stress response. Additionally, parthenolide treatment of human peripheral blood platelets attenuated activation of stimulated platelets. CONCLUSION Overall, these data reveal that parthenolide has strong potential as a candidate to enhance platelet production and to dampen undesirable platelet activation.
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Affiliation(s)
- Julie Sahler
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY, USA
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Giver CR, Jaye DL, Waller EK, Kaufman JL, Lonial S. Rapid recovery from panobinostat (LBH589)-induced thrombocytopenia in mice involves a rebound effect of bone marrow megakaryocytes. Leukemia 2010; 25:362-5. [DOI: 10.1038/leu.2010.262] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Séverin S, Ghevaert C, Mazharian A. The mitogen-activated protein kinase signaling pathways: role in megakaryocyte differentiation. J Thromb Haemost 2010; 8:17-26. [PMID: 19874462 DOI: 10.1111/j.1538-7836.2009.03658.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Megakaryopoiesis is a process by which bone marrow progenitor cells develop into mature megakaryocytes (MKs), which in turn produce platelets required for normal hemostasis. The mitogen-activated protein kinases (MAPKs) family comprises four main groups of proteins: extracellular signal-related kinases (ERKs) (ERK1/2 or p44/p42), ERK5, p38MAPKs (alpha, beta, gamma, delta) and c-Jun amino-terminal kinases (JNKs) (JNK 1, 2, 3). These intracellular signaling pathways play a pivotal role in many essential cellular processes including proliferation and differentiation. The purpose of this review is to summarize our current knowledge on the role of MAPKs in MKs, specifically regarding differentiation in immortalized cell lines and primary MKs. A critical role of the MEK (MAPK kinase)-ERK1/2 pathway in MK development has been demonstrated although the details remain controversial. There is at present no functional evidence for a role of p38MAPKs whereas the role of JNKs and ERK5 in MK development is not known. Characterization of these molecular event cascades remains crucial for the understanding of the megakaryopoiesis process.
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Affiliation(s)
- S Séverin
- Centre for Cardiovascular Sciences, Institute for Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
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15
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Beaulieu LM, Freedman JE. NFkappaB regulation of platelet function: no nucleus, no genes, no problem? J Thromb Haemost 2009; 7:1329-32. [PMID: 19500240 PMCID: PMC2826204 DOI: 10.1111/j.1538-7836.2009.03505.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- L M Beaulieu
- Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118, USA
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16
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Zheng C, Yang R, Han Z, Zhou B, Liang L, Lu M. TPO-independent megakaryocytopoiesis. Crit Rev Oncol Hematol 2008; 65:212-22. [PMID: 18093840 DOI: 10.1016/j.critrevonc.2007.11.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2006] [Revised: 06/19/2007] [Accepted: 11/08/2007] [Indexed: 12/25/2022] Open
Abstract
Megakaryocytopoiesis is a continuous developmental process of platelet production. In this process, a complex network of hemopoietic growth factors are involved, among which TPO (thrombopoietin) is the most thoroughly investigated regulator of MKs (megakaryocytes). In addition to TPO, other regulators also have non-negligible effects on megakaryocytopoiesis. The majority of their effects are independent of TPO signaling. To date, TPO-independent megakaryocytopoiesis forms a regulatory system that includes four signals and (an) unknown signaling pathway(s). These four pathways are the gp 130 (glycoprotein 130)-dependent signaling pathway, the Notch pathway, NMDA (N-methyl-d-aspartate) receptor-mediated signaling, and the SDF-1 (stromal cell-derived factor-1)/FGF-4 (fibroblast growth factor-4) paradigm. Understanding of the TPO-independent regulatory system is important because the system may offer additional opportunities to understand the developmental process and the mechanisms of disorders characterized by abnormal MK and platelet production, such as thrombocytopenia and thrombocythemia, and to advance the development of therapeutics.
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Affiliation(s)
- Cuiling Zheng
- State Key Laboratory of Experimental Hematology, Institute of Hematology, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, 300020, PR China
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Chen C, Fuhrken PG, Huang LT, Apostolidis P, Wang M, Paredes CJ, Miller WM, Papoutsakis ET. A systems-biology analysis of isogenic megakaryocytic and granulocytic cultures identifies new molecular components of megakaryocytic apoptosis. BMC Genomics 2007; 8:384. [PMID: 17953764 PMCID: PMC2204013 DOI: 10.1186/1471-2164-8-384] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Accepted: 10/22/2007] [Indexed: 12/17/2022] Open
Abstract
Background The differentiation of hematopoietic stem cells into platelet-forming megakaryocytes is of fundamental importance to hemostasis. Constitutive apoptosis is an integral, yet poorly understood, facet of megakaryocytic (Mk) differentiation. Understanding Mk apoptosis could lead to advances in the treatment of Mk and platelet disorders. Results We used a Gene-ontology-driven microarray-based transcriptional analysis coupled with protein-level and activity assays to identify genes and pathways involved in Mk apoptosis. Peripheral blood CD34+ hematopoietic progenitor cells were induced to either Mk differentiation or, as a negative control without observable apoptosis, granulocytic differentiation. Temporal gene-expression data were analyzed by a combination of intra- and inter-culture comparisons in order to identify Mk-associated genes. This novel approach was first applied to a curated set of general Mk-related genes in order to assess their dynamic transcriptional regulation. When applied to all apoptosis associated genes, it revealed a decrease in NF-κB signaling, which was explored using phosphorylation assays for IκBα and p65 (RELA). Up-regulation was noted among several pro-apoptotic genes not previously associated with Mk apoptosis such as components of the p53 regulon and TNF signaling. Protein-level analyses probed the involvement of the p53-regulated GADD45A, and the apoptosis signal-regulating kinase 1 (ASK1). Down-regulation of anti-apoptotic genes, including several of the Bcl-2 family, was also detected. Conclusion Our comparative approach to analyzing dynamic large-scale transcriptional data, which was validated using a known set of Mk genes, robustly identified candidate Mk apoptosis genes. This led to novel insights into the molecular mechanisms regulating apoptosis in Mk cells.
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Affiliation(s)
- Chi Chen
- Interdepartmental Biological Sciences Program, Northwestern University, Evanston, IL, USA.
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18
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Byts N, Samoylenko A, Woldt H, Ehrenreich H, Sirén AL. Cell type specific signalling by hematopoietic growth factors in neural cells. Neurochem Res 2006; 31:1219-30. [PMID: 17021950 DOI: 10.1007/s11064-006-9149-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 08/24/2006] [Indexed: 10/24/2022]
Abstract
Correct timing and spatial location of growth factor expression is critical for undisturbed brain development and functioning. In terminally differentiated cells distinct biological responses to growth factors may depend on cell type specific activation of signalling cascades. We show that the hematopoietic growth factors thrombopoietin (TPO) and granulocyte colony-stimulating factor (GCSF) exert cell type specific effects on survival, proliferation and the degree of phosphorylation of Akt1, ERK1/2 and STAT3 in rat hippocampal neurons and cortical astrocytes. In neurons, TPO induced cell death and selectively activated ERK1/2. GCSF protected neurons from TPO- and hypoxia-induced cell death via selective activation of Akt1. In astrocytes, neither TPO nor GCSF had any effect on cell viability but inhibited proliferation. This effect was accompanied by activation of ERK1/2 and inhibition of STAT3 activity. A balance between growth factors, their receptors and signalling proteins may play an important role in regulation of neural cell survival.
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Affiliation(s)
- Nadiya Byts
- Division of Clinical Neuroscience, Max-Planck-Institute of Experimental Medicine, Hermann-Rein-Str. 3, Göttingen, D-37075, Germany
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Yang D, Zhang Y, Nguyen HG, Koupenova M, Chauhan AK, Makitalo M, Jones MR, Hilaire CS, Seldin DC, Toselli P, Lamperti E, Schreiber BM, Gavras H, Wagner DD, Ravid K. The A2B adenosine receptor protects against inflammation and excessive vascular adhesion. J Clin Invest 2006; 116:1913-23. [PMID: 16823489 PMCID: PMC1483170 DOI: 10.1172/jci27933] [Citation(s) in RCA: 282] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Accepted: 04/25/2006] [Indexed: 01/22/2023] Open
Abstract
Adenosine has been described as playing a role in the control of inflammation, but it has not been certain which of its receptors mediate this effect. Here, we generated an A2B adenosine receptor-knockout/reporter gene-knock-in (A2BAR-knockout/reporter gene-knock-in) mouse model and showed receptor gene expression in the vasculature and macrophages, the ablation of which causes low-grade inflammation compared with age-, sex-, and strain-matched control mice. Augmentation of proinflammatory cytokines, such as TNF-alpha, and a consequent downregulation of IkappaB-alpha are the underlying mechanisms for an observed upregulation of adhesion molecules in the vasculature of these A2BAR-null mice. Intriguingly, leukocyte adhesion to the vasculature is significantly increased in the A2BAR-knockout mice. Exposure to an endotoxin results in augmented proinflammatory cytokine levels in A2BAR-null mice compared with control mice. Bone marrow transplantations indicated that bone marrow (and to a lesser extent vascular) A2BARs regulate these processes. Hence, we identify the A2BAR as a new critical regulator of inflammation and vascular adhesion primarily via signals from hematopoietic cells to the vasculature, focusing attention on the receptor as a therapeutic target.
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Affiliation(s)
- Dan Yang
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Ying Zhang
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Hao G. Nguyen
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Milka Koupenova
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Anil K. Chauhan
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Maria Makitalo
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Matthew R. Jones
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Cynthia St. Hilaire
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - David C. Seldin
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Paul Toselli
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Edward Lamperti
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Barbara M. Schreiber
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Haralambos Gavras
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Denisa D. Wagner
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Katya Ravid
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts, USA.
CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
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Nguyen HG, Chinnappan D, Urano T, Ravid K. Mechanism of Aurora-B degradation and its dependency on intact KEN and A-boxes: identification of an aneuploidy-promoting property. Mol Cell Biol 2005; 25:4977-92. [PMID: 15923616 PMCID: PMC1140599 DOI: 10.1128/mcb.25.12.4977-4992.2005] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The kinase Aurora-B, a regulator of chromosome segregation and cytokinesis, is highly expressed in a variety of tumors. During the cell cycle, the level of this protein is tightly controlled, and its deregulated abundance is suspected to contribute to aneuploidy. Here, we provide evidence that Aurora-B is a short-lived protein degraded by the proteasome via the anaphase-promoting cyclosome complex (APC/c) pathway. Aurora-B interacts with the APC/c through the Cdc27 subunit, Aurora-B is ubiquitinated, and its level is increased upon treatment with inhibitors of the proteasome. Aurora-B binds in vivo to the degradation-targeting proteins Cdh1 and Cdc20, the overexpression of which accelerates Aurora-B degradation. Using deletions or point mutations of the five putative degradation signals in Aurora-B, we show that degradation of this protein does not depend on its D-boxes (RXXL), but it does require intact KEN boxes and A-boxes (QRVL) located within the first 65 amino acids. Cells transfected with wild-type or A-box-mutated or KEN box-mutated Aurora-B fused to green fluorescent protein display the protein localized to the chromosomes and then to the midzone during mitosis, but the mutated forms are detected at greater intensities. Hence, we identified the degradation pathway for Aurora-B as well as critical regions for its clearance. Intriguingly, overexpression of a stable form of Aurora-B alone induces aneuploidy and anchorage-independent growth.
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Affiliation(s)
- Hao G Nguyen
- Department of Biochemistry, Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, K225, Boston, MA 02118, USA
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