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Life-threatening arrhythmogenic CaM mutations disrupt CaM binding to a distinct RyR2 CaM-binding pocket. Biochim Biophys Acta Gen Subj 2023; 1867:130313. [PMID: 36693454 DOI: 10.1016/j.bbagen.2023.130313] [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: 09/02/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 01/22/2023]
Abstract
Calmodulin (CaM) modulates the activity of several proteins that play a key role in excitation-contraction coupling (ECC). In cardiac muscle, the major binding partner of CaM is the type-2 ryanodine receptor (RyR2) and altered CaM binding contributes to defects in sarcoplasmic reticulum (SR) calcium (Ca2+) release. Many genetic studies have reported a series of CaM missense mutations in patients with a history of severe arrhythmogenic cardiac disorders. In the present study, we generated four missense CaM mutants (CaMN98I, CaMD132E, CaMD134H and CaMQ136P) and we used a CaM-RyR2 co-immunoprecipitation and a [3H]ryanodine binding assay to directly compare the relative RyR2-binding of wild type and mutant CaM proteins and to investigate the functional effects of these CaM mutations on RyR2 activity. Furthermore, isothermal titration calorimetry (ITC) experiments were performed to investigate and compare the interactions of the wild-type and mutant CaM proteins with various synthetic peptides located in the well-established RyR2 CaM-binding region (3584-3602aa), as well as another CaM-binding region (4255-4271aa) of human RyR2. Our data revealed that all four CaM mutants displayed dramatically reduced RyR2 interaction and defective modulation of [3H]ryanodine binding to RyR2, regardless of LQTS or CPVT association. Moreover, our isothermal titration calorimetry ITC data suggest that RyR2 3584-3602aa and 4255-4271aa regions interact with significant affinity with wild-type CaM, in the presence and absence of Ca2+, two regions that might contribute to a putative intra-subunit CaM-binding pocket. In contrast, screening the interaction of the four arrhythmogenic CaM mutants with two synthetic peptides that correspond to these RyR2 regions, revealed disparate binding properties and signifying differential mechanisms that contribute to reduced RyR2 association.
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Pan X, Zhu J, Xu Z, Xiao Q, Zhou X, Xu K, Li C, Jiang Y, Wang Y, Xue Z, Lei P, He Y. 68Ga-WRWWWW Is a Potential Positron Emission Tomography Probe for Imaging Inflammatory Diseases by Targeting Formyl Peptide Receptor 2. Mol Pharm 2022; 19:1368-1377. [PMID: 35393860 DOI: 10.1021/acs.molpharmaceut.1c00922] [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: 11/30/2022]
Abstract
Inflammation plays a significant role in many physiological and pathological processes. Molecular imaging could provide functional as well as anatomical information for visualizing various inflammatory diseases. Advancements in imaging tracers for inflammation would improve the accuracy of diagnosis and monitoring, thus facilitating patient care. The positron emission tomography (PET) imaging tracer, 68Ga-labeled antagonist peptide Trp-Arg-Trp-Trp-Trp-Trp (WRWWWW, WRW4), targets formyl peptide receptor 2 (FPR2), which is in turn widely distributed in a variety of tissues and is associated with many inflammatory diseases. In the current study, we aimed to investigate the potential of 68Ga-WRW4 for detecting and monitoring inflammatory lesions in mice. We established an inflammation mouse model by the intramuscular injection of turpentine oil into the left thigh. WRW4 was labeled with 68Ga with an overall radiochemical yield >90% and radiochemical purity >99%. 68Ga-WRW4 uptake in inflamed muscle peaked on day 2 (1.14 ± 0.01 percentage of the injected dose per gram of tissue (%ID/g)) and the uptake ratio of inflammatory/normal muscle also reached a maximum (12.36 ± 2.35). Strong PET signals were detected in the left thigh at 60 min after the injection of 68Ga-WRW4 in experimental mice, but weak or no signals were detected in mice in the blocking and control groups. 68Ga-WRW4 uptake was in agreement with the dynamics of immune cell infiltration during the inflammatory reaction. These results suggest that 68Ga-WRW4 is a promising PET tracer suitable for the noninvasive detection of FPR2 expression and for monitoring inflammatory activity in inflammation-bearing mice.
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Affiliation(s)
- Xin Pan
- Department of Nuclear Medicine, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei Province 430071, China
| | - Jiaxu Zhu
- Department of Nuclear Medicine, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei Province 430071, China
| | - Zhuoshuo Xu
- Department of Immunology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China
| | - Qin Xiao
- Department of Nuclear Medicine, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei Province 430071, China
| | - Xiaoqi Zhou
- Department of Immunology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China
| | - Kui Xu
- Department of Nuclear Medicine, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei Province 430071, China
| | - Chongjiao Li
- Department of Nuclear Medicine, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei Province 430071, China
| | - Yaqun Jiang
- Department of Nuclear Medicine, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei Province 430071, China
| | - Yichun Wang
- Department of Nuclear Medicine, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei Province 430071, China
| | - Zejian Xue
- Department of Nuclear Medicine, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei Province 430071, China
| | - Ping Lei
- Department of Immunology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei Province, China
| | - Yong He
- Department of Nuclear Medicine, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, Hubei Province 430071, China
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Karachaliou CE, Kostopoulos IV, Vassilakopoulou V, Klimentzou P, Paravatou-Petsotas M, Voelter W, Kalbacher H, Zikos C, Tsitsilonis O, Livaniou E. Development of a specific IgY-based ELISA for prothymosin alpha, a bioactive polypeptide with diagnostic and therapeutic potential. Heliyon 2019; 5:e02616. [PMID: 31720448 PMCID: PMC6838902 DOI: 10.1016/j.heliyon.2019.e02616] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 09/10/2019] [Accepted: 10/04/2019] [Indexed: 01/15/2023] Open
Abstract
Prothymosin alpha (ProTα) is a highly conserved polypeptide (109 amino acids in humans) with diagnostic and therapeutic potential; ProTα exerts intra- and extra-cellular biological functions associated with cell proliferation, apoptosis and immune regulation, while it has been suggested to act as a damage-associated molecular pattern (DAMP) or alarmin. In this work, chicken polyclonal anti-ProTα antibodies that had been developed several years ago were immunochemically evaluated and proven to retain immunoreactivity for ProTα, with remarkable thermal and pH stability. Moreover, the antibodies showed practically no cross-reactivity with a series of ProTα-fragments, eventually intracellularly produced -such as ProTα[1-28] (also known as Tα1) and ProTα[100-109], which exert per se biological activity and might be present in biological samples along with the intact molecule, being therefore highly specific for whole-length ProTα. Based on the above antibodies (IgYs-3e), a highly specific competitive ProTα-ELISA with well-studied analytical characteristics (intra- and inter-assay CVs: ≤5% and ≤12%, respectively, limit of detection: 2.1 ng/mL, recovery: 88–104%) was developed. The new ProTα-ELISA was applied to the analysis of supernatants of HeLa cells driven to necrosis; intact ProTα was measured in cell culture supernatants, at levels that seemed to depend on % cell necrosis.
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Affiliation(s)
- Chrysoula-Evangelia Karachaliou
- Institute of Nuclear & Radiological Sciences and Technology, Energy & Safety (INRASTES), National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Ioannis V Kostopoulos
- Department of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - Vyronia Vassilakopoulou
- Institute of Nuclear & Radiological Sciences and Technology, Energy & Safety (INRASTES), National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Persefoni Klimentzou
- Institute of Nuclear & Radiological Sciences and Technology, Energy & Safety (INRASTES), National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Maria Paravatou-Petsotas
- Institute of Nuclear & Radiological Sciences and Technology, Energy & Safety (INRASTES), National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Wolfgang Voelter
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany
| | - Hubert Kalbacher
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany
| | - Christos Zikos
- Institute of Nuclear & Radiological Sciences and Technology, Energy & Safety (INRASTES), National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Ourania Tsitsilonis
- Department of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - Evangelia Livaniou
- Institute of Nuclear & Radiological Sciences and Technology, Energy & Safety (INRASTES), National Centre for Scientific Research "Demokritos", Athens, Greece
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Fan Y, Zhang Q, Li H, Cheng Z, Li X, Chen Y, Shen Y, Wang L, Song G, Qian L. Peptidomics Analysis of Transient Regeneration in the Neonatal Mouse Heart. J Cell Biochem 2017; 118:2828-2840. [PMID: 28198139 DOI: 10.1002/jcb.25933] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 02/10/2017] [Indexed: 12/30/2022]
Abstract
Neonatal mouse hearts have completely regenerative capability after birth, but the ability to regenerate rapidly lost after 7 days, the mechanism has not been clarified. Previous studies have shown that mRNA profile of adult mouse changed greatly compared to neonatal mouse. So far, there is no research of peptidomics related to heart regeneration. In order to explore the changes of proteins, enzymes, and peptides related to the transient regeneration, we used comparative petidomics technique to compare the endogenous peptides in the mouse heart of postnatal 1 and 7 days. In final, we identified 236 differentially expressed peptides, 169 of which were upregulated and 67 were downregulated in the postnatal 1 day heart, and also predicted 36 functional peptides associated with transient regeneration. The predicted 36 candidate peptides are located in the important domains of precursor proteins and/or contain the post-transcriptional modification (PTM) sites, which are involved in the biological processes of cardiac development, cardiac muscle disease, cell proliferation, necrosis, and apoptosis. In conclusion, for the first time, we compared the peptidomics profiles of neonatal heart between postnatal 1 day and postnatal 7 day. This study provides a new direction and an important basis for the mechanism research of transient regeneration in neonatal heart. J. Cell. Biochem. 118: 2828-2840, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Yi Fan
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Qijun Zhang
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Hua Li
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Zijie Cheng
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Xing Li
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Yumei Chen
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Yahui Shen
- Departments of Cardiology, Taizhou People's Hospital, Taizhou 225300, China
| | - Liansheng Wang
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Guixian Song
- Departments of Cardiology, Taizhou People's Hospital, Taizhou 225300, China
| | - Lingmei Qian
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
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Karachaliou CE, Triantis C, Liolios C, Palamaris L, Zikos C, Tsitsilonis OE, Kalbacher H, Voelter W, Loudos G, Papadopoulos M, Pirmettis I, Livaniou E. In vivo biodistribution and imaging studies with a 99mTc-radiolabeled derivative of the C-terminus of prothymosin alpha in mice bearing experimentally-induced inflammation. Eur J Pharm Biopharm 2017; 113:188-197. [PMID: 28087377 DOI: 10.1016/j.ejpb.2016.12.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/15/2016] [Accepted: 12/14/2016] [Indexed: 10/20/2022]
Abstract
Prothymosin alpha (ProTα) is a highly conserved mammalian polypeptide (109 amino acids in man) exerting in vitro and in vivo immunoenhancing activities. Recently, our team has developed a 99mTc-radiolabeled derivative of the C-terminal bioactive decapeptide of ProTα ([99mTc]C1) and employed it in in vitro studies, the results of which support the existence of binding sites on human neutrophils that recognize [99mTc]C1, intact ProTα as well as the C-terminal decapeptide of ProTα and presumably involve Toll-like receptor 4. In the present work, [99mTc]C1 was administered to Swiss albino mice with experimentally-induced inflammation for in vivo biodistribution and imaging studies, in parallel with a suitable negative control, which differs from [99mTc]C1 only in bearing a scrambled version of the ProTα decapeptide. The biodistribution data obtained with [99mTc]C1 demonstrated fast clearance of radioactivity from blood, heart, lungs, normal muscle, and predominantly urinary excretion. Most importantly, slow clearance of radioactivity from the inflammation focus was observed, resulting in a high ratio of inflamed/normal muscle tissue (9.15 at 30min post injection, which remained practically stable up to 2h). The inflammation-targeting capacity of [99mTc]C1 was confirmed by imaging studies and might be attributed to neutrophils, which are recruited at the inflamed areas and bear binding sites for [99mTc]C1. In this respect, apart from being a valuable tool for further studies on ProTα in in vitro and in vivo systems, [99mTc]C1 merits further evaluation as a radiopharmaceutical for specific imaging of inflammation foci.
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Affiliation(s)
- Chrysoula-Evangelia Karachaliou
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Charalampos Triantis
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Christos Liolios
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Lazaros Palamaris
- Department of Medical Instruments Technology, Technological Educational Institute, Athens 12243, Greece
| | - Christos Zikos
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Ourania E Tsitsilonis
- Division of Animal and Human Physiology, Department of Biology, University of Athens, Athens 15784, Greece
| | - Hubert Kalbacher
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen 72076, Germany
| | - Wolfgang Voelter
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen 72076, Germany
| | - George Loudos
- Department of Medical Instruments Technology, Technological Educational Institute, Athens 12243, Greece
| | - Minas Papadopoulos
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Ioannis Pirmettis
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece
| | - Evangelia Livaniou
- Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety (INRASTES), National Center for Scientific Research "Demokritos" (NCSR "Demokritos"), Athens 15310, Greece.
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Gusella GL, Teixeira A, Aberg J, Uversky VN, Mosoian A. Prothymosin-α Variants Elicit Anti-HIV-1 Response via TLR4 Dependent and Independent Pathways. PLoS One 2016; 11:e0156486. [PMID: 27310139 PMCID: PMC4910978 DOI: 10.1371/journal.pone.0156486] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 04/22/2016] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Prothymosin α (ProTα) (isoform 2: iso2) is a widely distributed, small acidic protein with intracellular and extracellular-associated functions. Recently, we identified two new ProTα variants with potent anti-HIV activity from CD8+ T cells and cervicovaginal lavage. The first is a splice variant of the ProTα gene known as isoB and the second is the product of ProTα pseudogene 7 (p7). Similarly to iso2, the anti-HIV activity of both variants is mediated by type I IFN. Here we tested whether the immunomodulatory activity of isoB and p7 are also TLR4 dependent and determined their kinetic of release in response to HIV-1 infection. METHODS Type I, type III, TNF-α and IL-6 mRNA inducing activity was determined in macrophages from wild type and TLR4 knockout mice treated with recombinant ProTα variants. Supernatants from mock and HIV infected cells were analyzed by mass spectrometry in positive and negative modes for the presence of ProTα variants. In silico structural and functional analysis of ProTα variants were performed. RESULTS We show that both isoB and p7 upregulate IFN-β, IFN-λ1, IL-6, TNF-α and RANTES mRNAs in primary human macrophages. The potent stimulation of IFN-β by the recombinant ProTα variants in human macrophages is dependent on the TLR4 pathway, whereas the induction of TNF-α and IL-6 may also occur independently of TLR4, suggesting the interaction of ProTα variants with other signaling molecules/receptors. In silico analyses confirmed that the novel isoB and p7 variants are intrinsically disordered proteins, which lack the NLS and mass spectrometry showed release of ProTα variants within minutes post HIV-1 infection. These features are consistent with the function of ProTα variants as damage associate molecular patterns (DAMPs). CONCLUSIONS Our findings indicate that ProTα variants strongly inhibit viral replication mainly, but not exclusively, through TLR4 signaling and that they are released within minutes of viral infection suggesting that they may function as DAMPs.
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Affiliation(s)
- G. Luca Gusella
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Avelino Teixeira
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Judith Aberg
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Vladimir N. Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, United States of America
- Biology Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Kingdom of Saudi Arabia
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russian Federation
| | - Arevik Mosoian
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
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Ueda H, Halder SK, Matsunaga H, Sasaki K, Maeda S. Neuroprotective impact of prothymosin alpha-derived hexapeptide against retinal ischemia-reperfusion. Neuroscience 2016; 318:206-18. [PMID: 26779836 DOI: 10.1016/j.neuroscience.2016.01.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 12/17/2015] [Accepted: 01/05/2016] [Indexed: 01/13/2023]
Abstract
Prothymosin alpha (ProTα) has robustness roles against brain and retinal ischemia or serum-starvation stress. In the ProTα sequence, the active core 30-amino acid peptide/P30 (a.a.49-78) is necessary for the original neuroprotective actions against ischemia. Moreover, the 9-amino acid peptide sequence/P9 (a.a.52-60) in P30 still shows neuroprotective activity against brain and retinal ischemia, though P9 is less potent than P30. As the previous structure-activity relationship study for ProTα may not be enough, the possibility still exists that any sequence smaller than P9 retains potent neuroprotective activity. When different P9- and P30-related peptides were intravitreally injected 24h after retinal ischemia in mice, the 6-amino acid peptide/P6 (NEVDEE, a.a.51-56) showed potent protective effects against ischemia-induced retinal functional deficits, which are equipotent to the level of P30 peptide in electroretinography (ERG) and histological damage in Hematoxylin and Eosin (HE) staining. Further studies using ERG and HE staining suggested that intravitreal or intravenous (i.v.) injection with modified P6 peptide/P6Q (NEVDQE) potently inhibited retinal ischemia-induced functional and histological damage. In an immunohistochemical analysis, the ischemia-induced loss of retinal ganglion, bipolar, amacrine and photoreceptor cells were inhibited by a systemic administration with P6Q peptide 24h after the ischemic stress. In addition, systemic post-treatment with P6Q peptide significantly inhibited retinal ischemia-induced microglia and astrocyte activation in terms of increased ionized calcium-binding adaptor molecule 1 (Iba-1) and glial fibrillary acidic protein (GFAP) intensity, respectively, as well as their morphological changes, increased number and migration. Thus, this study demonstrates the therapeutic significance of modified P6 peptide P6Q (NEVDQE) derived from 6-amino acid peptide (P6) in ProTα against ischemic damage.
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Affiliation(s)
- H Ueda
- Department of Pharmacology and Therapeutic Innovation, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8521, Japan.
| | - S K Halder
- Department of Pharmacology and Therapeutic Innovation, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8521, Japan
| | - H Matsunaga
- Department of Pharmacology and Therapeutic Innovation, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8521, Japan
| | - K Sasaki
- Department of Pharmacology and Therapeutic Innovation, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8521, Japan
| | - S Maeda
- Department of Pharmacology and Therapeutic Innovation, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8521, Japan
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Prothymosin Alpha and Immune Responses: Are We Close to Potential Clinical Applications? VITAMINS AND HORMONES 2016; 102:179-207. [PMID: 27450735 PMCID: PMC7126549 DOI: 10.1016/bs.vh.2016.04.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The thymus gland produces soluble molecules, which mediate significant immune functions. The first biologically active thymic extract was thymosin fraction V, the fractionation of which led to the isolation of a series of immunoactive polypeptides, including prothymosin alpha (proTα). ProTα displays a dual role, intracellularly as a survival and proliferation mediator and extracellularly as a biological response modifier. Accordingly, inside the cell, proTα is implicated in crucial intracellular circuits and may serve as a surrogate tumor biomarker, but when found outside the cell, it could be used as a therapeutic agent for treating immune system deficiencies. In fact, proTα possesses pleiotropic adjuvant activity and a series of immunomodulatory effects (eg, anticancer, antiviral, neuroprotective, cardioprotective). Moreover, several reports suggest that the variable activity of proTα might be exerted through different parts of the molecule. We first reported that the main immunoactive region of proTα is the carboxy-terminal decapeptide proTα(100-109). In conjunction with data from others, we also revealed that proTα and proTα(100-109) signal through Toll-like receptor 4. Although their precise molecular mechanism of action is yet not fully elucidated, proTα and proTα(100-109) are viewed as candidate adjuvants for cancer immunotherapy. Here, we present a historical overview on the discovery and isolation of thymosins with emphasis on proTα and data on some immune-related new activities of the polypeptide and smaller immunostimulatory peptides thereof. Finally, we propose a compiled scenario on proTα's mode of action, which could eventually contribute to its clinical application.
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