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Kriaučiūnaitė K, Pociūtė A, Kaušylė A, Verkhratsky A, Pivoriūnas A. Basic Fibroblast Growth Factor Opens and Closes the Endothelial Blood-Brain Barrier in a Concentration-Dependent Manner. Neurochem Res 2023; 48:1211-1221. [PMID: 35859077 DOI: 10.1007/s11064-022-03678-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 06/23/2022] [Accepted: 07/05/2022] [Indexed: 10/17/2022]
Abstract
Multiple paracrine factors are implicated in the regulation of barrier properties of human brain endothelial cells (BECs) in different physiologic and pathologic settings. We have recently demonstrated that autocrine secretion of basic fibroblast growth factor (bFGF) by BECs is necessary for the establishment of endothelial barrier (as demonstrated by high trans-endothelial electric resistance, TEER), whereas exogenous bFGF inhibits TEER in a concentration-dependent manner. In the present study we analysed the contribution of MAPK/ERK and STAT3 signalling pathways to the inhibitory effects of exogenous bFGF. Treatment with bFGF (8 ng/ml) for 3 days increased phosphorylation of ERK1/2 and STAT3. Treatment with FGF receptor 1 (FGFR1) inhibitor PD173074 (15 μM) suppressed both basal and bFGF-induced activation of ERK1/2 and STAT3. Suppression of STAT signalling with Janus kinase inhibitor JAKi (15 nM) alone or in the presence of bFGF did not change TEER in BEC monolayers. Exposure to JAKi affected neither proliferation, nor expression and distribution of tight junction (TJ) proteins claudin-5, occludin and zonula occludens-1 (ZO-1). In contrast, treatment with MEK 1/2 inhibitor U0126 (10 μM) partially neutralised inhibitory effect of bFGF thus increasing TEER, whereas U0126 alone did not affect resistance of endothelial barrier. Our findings demonstrate that MAPK/ERK signalling pathway does not affect autocrine bFGF signalling-dependent BECs barrier function but is largely responsible for the disruptive effects of the exogenous bFGF. We speculate that bFGF may (depending on concentration and possibly origin) dynamically regulate permeability of the endothelial blood-brain barrier.
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Affiliation(s)
- Karolina Kriaučiūnaitė
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, 01102, Vilnius, Lithuania
| | - Agnė Pociūtė
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, 01102, Vilnius, Lithuania
| | - Aida Kaušylė
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, 01102, Vilnius, Lithuania
| | - Alexei Verkhratsky
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, 01102, Vilnius, Lithuania.
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK.
- IKERBASQUE, Basque Foundation for Science, Achucarro Centre for Neuroscience, 48011, Bilbao, Spain.
| | - Augustas Pivoriūnas
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, 01102, Vilnius, Lithuania.
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Erdogan F, Qadree AK, Radu TB, Orlova A, de Araujo ED, Israelian J, Valent P, Mustjoki SM, Herling M, Moriggl R, Gunning PT. Structural and mutational analysis of member-specific STAT functions. Biochim Biophys Acta Gen Subj 2022; 1866:130058. [PMID: 34774983 DOI: 10.1016/j.bbagen.2021.130058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 10/29/2021] [Accepted: 11/05/2021] [Indexed: 12/21/2022]
Abstract
BACKGROUND The STAT family of transcription factors control gene expression in response to signals from various stimulus. They display functions in diseases ranging from autoimmunity and chronic inflammatory disease to cancer and infectious disease. SCOPE OF REVIEW This work uses an approach informed by structural data to explore how domain-specific structural variations, post-translational modifications, and the cancer genome mutational landscape dictate STAT member-specific activities. MAJOR CONCLUSIONS We illustrated the structure-function relationship of STAT proteins and highlighted their effect on member-specific activity. We correlated disease-linked STAT mutations to the structure and cancer genome mutational landscape and proposed rational drug targeting approaches of oncogenic STAT pathway addiction. GENERAL SIGNIFICANCE Hyper-activated STATs and their variants are associated with multiple diseases and are considered high value oncology targets. A full understanding of the molecular basis of member-specific STAT-mediated signaling and the strategies to selectively target them requires examination of the difference in their structures and sequences.
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Affiliation(s)
- Fettah Erdogan
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada
| | - Abdul K Qadree
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada
| | - Tudor B Radu
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada
| | - Anna Orlova
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, A-1210 Vienna, Austria
| | - Elvin D de Araujo
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada
| | - Johan Israelian
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada
| | - Peter Valent
- Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of Vienna, Vienna, Austria
| | - Satu M Mustjoki
- Hematology Research Unit, Helsinki University Hospital Comprehensive Cancer Center, Helsinki, Finland; Translational Immunology Research Program and Department of Clinical Chemistry and Hematology, University of Helsinki, Helsinki, Finland; iCAN Digital Precision Cancer Medicine Flagship, Helsinki, Finland
| | - Marco Herling
- Department of Hematology, Cellular Therapy, and Hemostaseology, University of Leipzig, Leipzig, Germany
| | - Richard Moriggl
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, A-1210 Vienna, Austria
| | - Patrick T Gunning
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, Canada; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Canada.
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Vesicular formation regulated by ERK/MAPK pathway mediates human erythroblast enucleation. Blood Adv 2021; 5:4648-4661. [PMID: 34551066 PMCID: PMC8759143 DOI: 10.1182/bloodadvances.2021004859] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 07/17/2021] [Indexed: 11/20/2022] Open
Abstract
ERK pathway plays a key role in enucleation of human orthochromatic erythroblasts. ERK regulates human erythroblast enucleation by affecting vesicular formation.
Enucleation is a key event in mammalian erythropoiesis responsible for the generation of enucleated reticulocytes. Although progress is being made in developing mechanistic understanding of enucleation, our understanding of mechanisms for enucleation is still incomplete. The MAPK pathway plays diverse roles in biological processes, but its role in erythropoiesis has yet to be fully defined. Analysis of RNA-sequencing data revealed that the MAPK pathway is significantly upregulated during human terminal erythroid differentiation. The MAPK pathway consists of 3 major signaling cassettes: MEK/ERK, p38, and JNK. In the present study, we show that among these 3 cassettes, only ERK was significantly upregulated in late-stage human erythroblasts. The increased expression of ERK along with its increased phosphorylation suggests a potential role for ERK activation in enucleation. To explore this hypothesis, we treated sorted populations of human orthochromatic erythroblasts with the MEK/ERK inhibitor U0126 and found that U0126 inhibited enucleation. In contrast, inhibitors of either p38 or JNK had no effect on enucleation. Mechanistically, U0126 selectively inhibited formation/accumulation of cytoplasmic vesicles and endocytosis of the transferrin receptor without affecting chromatin condensation, nuclear polarization, or enucleosome formation. Treatment with vacuolin-1 that induces vacuole formation partially rescued the blockage of enucleation by U0126. Moreover, phosphoproteomic analysis revealed that inactivation of the ERK pathway led to downregulation of the endocytic recycling pathway. Collectively, our findings uncovered a novel role of ERK activation in human erythroblast enucleation by modulating vesicle formation and have implications for understanding anemia associated with defective enucleation.
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Type I interferon activation and endothelial dysfunction in caveolin-1 insufficiency-associated pulmonary arterial hypertension. Proc Natl Acad Sci U S A 2021; 118:2010206118. [PMID: 33836561 DOI: 10.1073/pnas.2010206118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interferonopathies, interferon (IFN)-α/β therapy, and caveolin-1 (CAV1) loss-of-function have all been associated with pulmonary arterial hypertension (PAH). Here, CAV1-silenced primary human pulmonary artery endothelial cells (PAECs) were proliferative and hypermigratory, with reduced cytoskeletal stress fibers. Signal transducers and activators of transcription (STAT) and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) were both constitutively activated in these cells, resulting in a type I IFN-biased inflammatory signature. Cav1 -/- mice that spontaneously develop pulmonary hypertension were found to have STAT1 and AKT activation in lung homogenates and increased circulating levels of CXCL10, a hallmark of IFN-mediated inflammation. PAH patients with CAV1 mutations also had elevated serum CXCL10 levels and their fibroblasts mirrored phenotypic and molecular features of CAV1-deficient PAECs. Moreover, immunofluorescence staining revealed endothelial CAV1 loss and STAT1 activation in the pulmonary arterioles of patients with idiopathic PAH, suggesting that this paradigm might not be limited to rare CAV1 frameshift mutations. While blocking JAK/STAT or AKT rescued aspects of CAV1 loss, only AKT inhibitors suppressed activation of both signaling pathways simultaneously. Silencing endothelial nitric oxide synthase (NOS3) prevented STAT1 and AKT activation induced by CAV1 loss, implicating CAV1/NOS3 uncoupling and NOS3 dysregulation in the inflammatory phenotype. Exogenous IFN reduced CAV1 expression, activated STAT1 and AKT, and altered the cytoskeleton of PAECs, implicating these mechanisms in PAH associated with autoimmune and autoinflammatory diseases, as well as IFN therapy. CAV1 insufficiency elicits an IFN inflammatory response that results in a dysfunctional endothelial cell phenotype and targeting this pathway may reduce pathologic vascular remodeling in PAH.
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AMPK alleviates oxidative stress‑induced premature senescence via inhibition of NF-κB/STAT3 axis-mediated positive feedback loop. Mech Ageing Dev 2020; 191:111347. [PMID: 32882228 DOI: 10.1016/j.mad.2020.111347] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 08/17/2020] [Accepted: 08/28/2020] [Indexed: 01/10/2023]
Abstract
Stress-induced premature senescence (SIPS) is characterized by the secretion of a variety of inflammatory cytokines, chemokines, and proteases, which are defined collectively as the senescence-associated secretory phenotype (SASP). AMP-activated protein kinase (AMPK) activation contributes to SIPS prevention, and the impact of AMPK on SASP may be included, but the mechanisms governing this phenomenon have not elucidated. In this study, we showed that SIPS is accompanied by a dynamic fluctuation of NF-κB activation, which induces SASP production, whilst reinforcing and amplifying local STAT3 signalling and subsequently enhancing downstream senescence. NF-κB and STAT3 inhibitors attenuate oxidative stress-induced senescence in a time-dependent manner. Conditioned medium (CM) from senescent cells rich in SASP factors can induce growth arrest and promote senescence in healthy cells; accordingly, a STAT3 inhibitor blunts the SASP-induced senescence, indicating a positive feedback mechanism via the NF-κB/STAT3 pathway that sustains SASP production and promotes senescence. In addition, we confirmed that AMPK negatively regulates SASP production and senescence development associated with NF-κB/STAT3 inhibition. In summary, our results suggest that AMPK prevents oxidative stress-induced senescence development via inhibiting the NF-κB/SASP/STAT3 signalling mediated positive feedback loop.
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Li J, Tao T, Xu J, Liu Z, Zou Z, Jin M. HIF‑1α attenuates neuronal apoptosis by upregulating EPO expression following cerebral ischemia‑reperfusion injury in a rat MCAO model. Int J Mol Med 2020; 45:1027-1036. [PMID: 32124933 PMCID: PMC7053873 DOI: 10.3892/ijmm.2020.4480] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 12/30/2019] [Indexed: 01/16/2023] Open
Abstract
Hypoxia-inducible factor-1α (HIF-1α) is a key transcriptional factor in response to hypoxia and is involved in ischemic stroke. In the present study, the potential for HIF-1α to inhibit neuronal apoptosis through upregulating erythropoietin (EPO) was investigated in a transient middle cerebral artery occlusion (tMCAO) rat stroke model. For this purpose, a recombinant adenovirus expressing HIF-1α was engineered (Ad-HIF-1α). Control adenovirus (Ad group), Ad-HIF-1α (Ad-HIF-1α group) or Ad-HIF-1α in addition to erythropoietin mimetic peptide-9 (EMP9), an EPO-receptor (-R) antagonist (Ad-HIF-1α+EMP9 group), were used for an intracranial injection into rat ischemic penumbra 1 h following MCAO. All rats demonstrated functional improvement following tMCAO, while the improvement rate was faster in rats treated by Ad-HIF-1α compared with all other groups. The EPO-R inhibitor partially reversed the benefits of Ad-HIF-1α. Apoptosis induced by tMCAO was significantly inhibited by Ad-HIF-1α (P<0.05). The expression of HIF-1α, evaluated by immunohistochemistry either in neurons or astrocytes, was upregulated by Ad-HIF-1α. Both EPO mRNA and protein expression were increased by Ad-HIF-1α, however, there was no significant change of EPO-R either on an mRNA level or protein level. Furthermore, EMP9 did not change the EPO expression which was upregulated by Ad-HIF-1α. Activated caspase 3 in neurons was suppressed by Ad-HIF-1α. Activated caspase 3 downregulated by HIF-1α was partially blocked by EMP9. Altogether, the present data demonstrated that HIF-1α attenuates neuronal apoptosis partially through upregulating EPO following cerebral ischemia in rat. Thus, upregulating HIF-1α subsequent to a stroke may be a potential treatment for ischemic stroke.
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Affiliation(s)
- Jun Li
- Department of Rehabilitation Medicine, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
| | - Tao Tao
- Department of Rehabilitation Medicine, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
| | - Jian Xu
- Department of Neurology, The Affiliated Hospital Guizhou Medical University, Guiyang, Guizhou 550001, P.R. China
| | - Zhi Liu
- Department of Pharmacy, The Affiliated Hospital Guizhou Medical University, Guiyang, Guizhou 550001, P.R. China
| | - Zhehua Zou
- Department of General Practice, The First Hospital of Qinhuangdao, Qinhuangdao, Hebei 066000, P.R. China
| | - Minglu Jin
- Department of Neurology, Qijiang Hospital of The First Affiliated Hospital of Chongqing Medical University, Chongqing 404100, P.R. China
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Pham TND, Ma W, Miller D, Kazakova L, Benchimol S. Erythropoietin inhibits chemotherapy-induced cell death and promotes a senescence-like state in leukemia cells. Cell Death Dis 2019; 10:22. [PMID: 30622244 PMCID: PMC6325163 DOI: 10.1038/s41419-018-1274-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 12/03/2018] [Accepted: 12/07/2018] [Indexed: 12/11/2022]
Abstract
There are conflicting reports on the adverse effects of erythropoietin (EPO) for the management of cancer-associated anemia. The recognition that erythropoietin receptors (EPORs) are expressed outside the erythroid lineage and concerns that erythropoiesis-stimulating agents (ESAs) may cause tumors to grow and increase the risk of venous thromboembolism have resulted in substantially fewer cancer patients receiving ESA therapy to manage myelosuppressive chemotherapy. In this study, we found that EPO suppresses p53-dependent apoptosis induced by genotoxic (daunorubicin, doxorubicin, and γ-radiation) and non-genotoxic (nutlin-3a) agents and induces a senescence-like state in myeloid leukemia cells. EPO interferes with stress-dependent Mdm2 downregulation and leads to the destabilization of p53 protein. EPO selectively modulates the expression of p53 target genes in response to DNA damage preventing the induction of a number of noncoding RNAs (ncRNAs) previously associated with p53-dependent apoptosis. EPO also enhances the expression of the cyclin-dependent kinase inhibitor p21WAF1 and promotes recruitment of p53 to the p21 promoter. In addition, EPO antagonizes Mcl-1 protein degradation in daunorubicin-treated cells. Hence, EPO signaling targets Mcl-1 expression and the p53-Mdm2 network to promote tumor cell survival.
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Affiliation(s)
| | - Weili Ma
- Department of Biology, York University, Toronto, ON, M3J 1P3, Canada
| | - David Miller
- Department of Biology, York University, Toronto, ON, M3J 1P3, Canada
| | - Lidia Kazakova
- Department of Biology, York University, Toronto, ON, M3J 1P3, Canada
| | - Samuel Benchimol
- Department of Biology, York University, Toronto, ON, M3J 1P3, Canada.
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8
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Nan Y, Wu C, Zhang YJ. Interferon Independent Non-Canonical STAT Activation and Virus Induced Inflammation. Viruses 2018; 10:v10040196. [PMID: 29662014 PMCID: PMC5923490 DOI: 10.3390/v10040196] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/07/2018] [Accepted: 04/11/2018] [Indexed: 02/06/2023] Open
Abstract
Interferons (IFNs) are a group of secreted proteins that play critical roles in antiviral immunity, antitumor activity, activation of cytotoxic T cells, and modulation of host immune responses. IFNs are cytokines, and bind receptors on cell surfaces to trigger signal transduction. The major signaling pathway activated by IFNs is the JAK/STAT (Janus kinase/signal transducer and activator of transcription) pathway, a complex pathway involved in both viral and host survival strategies. On the one hand, viruses have evolved strategies to escape from antiviral host defenses evoked by IFN-activated JAK/STAT signaling. On the other hand, viruses have also evolved to exploit the JAK/STAT pathway to evoke activation of certain STATs that somehow promote viral pathogenesis. In this review, recent progress in our understanding of the virus-induced IFN-independent STAT signaling and its potential roles in viral induced inflammation and pathogenesis are summarized in detail, and perspectives are provided.
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Affiliation(s)
- Yuchen Nan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China.
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD 20742, USA.
| | - Chunyan Wu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China.
| | - Yan-Jin Zhang
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, MD 20742, USA.
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Yashiro M, Ohya M, Mima T, Ueda Y, Nakashima Y, Kawakami K, Ishizawa Y, Yamamoto S, Kobayashi S, Yano T, Tanaka Y, Okuda K, Sonou T, Shoshihara T, Iwashita Y, Iwashita Y, Tatsuta K, Matoba R, Negi S, Shigematsu T. FGF23 modulates the effects of erythropoietin on gene expression in renal epithelial cells. Int J Nephrol Renovasc Dis 2018; 11:125-136. [PMID: 29670389 PMCID: PMC5894721 DOI: 10.2147/ijnrd.s158422] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Background FGF23 plays an important role in calcium–phosphorus metabolism. Other roles of FGF23 have recently been reported, such as commitment to myocardium enlargement and immunological roles in the spleen. In this study, we aimed to identify the roles of FGF23 in the kidneys other than calcium–phosphorus metabolism. Methods DNA microarrays and bioinformatics tools were used to analyze gene expression in mIMCD3 mouse renal tubule cells following treatment with FGF23, erythropoietin and/or an inhibitor of ERK. Results Three protein-coding genes were upregulated and 12 were downregulated in response to FGF23. Following bioinformatics analysis of these genes, PPARγ and STAT3 were identified as candidate transcript factors for mediating their upregulation, and STAT1 as a candidate for mediating their downregulation. Because STAT1 and STAT3 also mediate erythropoietin signaling, we investigated whether FGF23 and erythropoietin might show interactive effects in these cells. Of the 15 genes regulated by FGF23, 11 were upregulated by erythropoietin; 10 of these were downregulated following cotreatment with FGF23. Inhibition of ERK, an intracellular mediator of FGF23, reversed the effects of FGF23. However, FGF23 did not influence STAT1 phosphorylation, suggesting that it impinges on erythropoietin signaling through other mechanisms. Conclusion Our results suggest cross talk between erythropoietin and FGF23 signaling in the regulation of renal epithelial cells.
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Affiliation(s)
- Mitsuru Yashiro
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Masaki Ohya
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Toru Mima
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Yumi Ueda
- DNA Chip Research Inc., Minato, Japan
| | - Yuri Nakashima
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Kazuki Kawakami
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | | | - Shuto Yamamoto
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Sou Kobayashi
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Takurou Yano
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Yusuke Tanaka
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Kouji Okuda
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Tomohiro Sonou
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | | | - Yuko Iwashita
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Yu Iwashita
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | - Kouichi Tatsuta
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
| | | | - Shigeo Negi
- Department of Nephrology, Wakayama Medical University, Wakayama, Japan
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Nan Y, Wu C, Zhang YJ. Interplay between Janus Kinase/Signal Transducer and Activator of Transcription Signaling Activated by Type I Interferons and Viral Antagonism. Front Immunol 2017; 8:1758. [PMID: 29312301 PMCID: PMC5732261 DOI: 10.3389/fimmu.2017.01758] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 11/27/2017] [Indexed: 12/13/2022] Open
Abstract
Interferons (IFNs), which were discovered a half century ago, are a group of secreted proteins that play key roles in innate immunity against viral infection. The major signaling pathway activated by IFNs is the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway, which leads to the expression of IFN-stimulated genes (ISGs), including many antiviral effectors. Viruses have evolved various strategies with which to antagonize the JAK/STAT pathway to influence viral virulence and pathogenesis. In recent years, notable progress has been made to better understand the JAK/STAT pathway activated by IFNs and antagonized by viruses. In this review, recent progress in research of the JAK/STAT pathway activated by type I IFNs, non-canonical STAT activation, viral antagonism of the JAK/STAT pathway, removing of the JAK/STAT antagonist from viral genome for attenuation, and the potential pathogenesis roles of tyrosine phosphorylation-independent non-canonical STATs activation during virus infection are discussed in detail. We expect that this review will provide new insight into the understanding the complexity of the interplay between JAK/STAT signaling and viral antagonism.
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Affiliation(s)
- Yuchen Nan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, China.,Molecular Virology Laboratory, VA-MD Regional College of Veterinary Medicine, Maryland Pathogen Research Institute, University of Maryland, College Park, MD, United States
| | - Chunyan Wu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yan-Jin Zhang
- Molecular Virology Laboratory, VA-MD Regional College of Veterinary Medicine, Maryland Pathogen Research Institute, University of Maryland, College Park, MD, United States
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Thermal injury of the skin induces G-CSF-dependent attenuation of EPO-mediated STAT signaling and erythroid differentiation arrest in mice. Exp Hematol 2017; 56:16-30. [PMID: 28867537 DOI: 10.1016/j.exphem.2017.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 07/13/2017] [Accepted: 08/25/2017] [Indexed: 12/18/2022]
Abstract
Inflammation-mediated impairment of erythropoiesis plays a central role in the development of the anemia of critical illness (ACI). ACI develops despite elevation of endogenous erythropoietin (EPO), does not respond to exogenous erythropoietin (EPO) supplementation, and contributes significantly to transfusion requirements in burned patients. We have reported previously that the reduction of red blood cell mass in the bone marrow of a burn-injured ACI mouse model is granulocyte colony-stimulating factor (G-CSF) dependent. Given that elevated G-CSF levels also have been associated with lower hemoglobin levels and increased transfusion requirements in trauma victims, we postulated that G-CSF mediates postburn EPO resistance. In ACI mice, we found that bone marrow erythroid differentiation, viability, and proliferation are impaired after thermal injury of the skin. These changes in the marrow were associated with attenuated phosphorylation of known EPO-responsive signaling nodes, signal transducer and activator of transcription 5 (STAT5) Y694 and STAT3 S727, in bone marrow erythroid cells and developed despite highly elevated levels of endogenous EPO. Severely blunted STAT5 Y694 phosphorylation in bone marrow erythroid cells after exogenous EPO supplementation confirmed that EPO signaling was impaired in ACI mice. Importantly, parenteral administration of anti-G-CSF largely rescued postburn bone marrow erythroid differentiation arrest and EPO signaling in erythroid cells. Together, these data provide strong evidence for a role for G-CSF in the development of ACI after burn injury through suppression of EPO signaling in bone marrow erythroid cells.
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Visavadiya NP, Keasey MP, Razskazovskiy V, Banerjee K, Jia C, Lovins C, Wright GL, Hagg T. Integrin-FAK signaling rapidly and potently promotes mitochondrial function through STAT3. Cell Commun Signal 2016; 14:32. [PMID: 27978828 PMCID: PMC5159999 DOI: 10.1186/s12964-016-0157-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 12/06/2016] [Indexed: 01/02/2023] Open
Abstract
Background STAT3 is increasingly becoming known for its non-transcriptional regulation of mitochondrial bioenergetic function upon activation of its S727 residue (S727-STAT3). Lengthy mitochondrial dysfunction can lead to cell death. We tested whether an integrin-FAK-STAT3 signaling pathway we recently discovered regulates mitochondrial function and cell survival, and treatments thereof. Methods Cultured mouse brain bEnd5 endothelial cells were treated with integrin, FAK or STAT3 inhibitors, FAK siRNA, as well as integrin and STAT3 activators. STAT3 null cells were transfected with mutant STAT3 plasmids. Outcome measures included oxygen consumption rate for mitochondrial bioenergetics, Western blotting for protein phosphorylation, mitochondrial membrane potential for mitochondrial integrity, ROS production, and cell counts. Results Vitronectin-dependent mitochondrial basal respiration, ATP production, and maximum reserve and respiratory capacities were suppressed within 4 h by RGD and αvβ3 integrin antagonist peptides. Conversely, integrin ligands vitronectin, laminin and fibronectin stimulated mitochondrial function. Pharmacological inhibition of FAK completely abolished mitochondrial function within 4 h while FAK siRNA treatments confirmed the specificity of FAK signaling. WT, but not S727A functionally dead mutant STAT3, rescued bioenergetics in cells made null for STAT3 using CRISPR-Cas9. STAT3 inhibition with stattic in whole cells rapidly reduced mitochondrial function and mitochondrial pS727-STAT3. Stattic treatment of isolated mitochondria did not reduce pS727 whereas more was detected upon phosphatase inhibition. This suggests that S727-STAT3 is activated in the cytoplasm and is short-lived upon translocation to the mitochondria. FAK inhibition reduced pS727-STAT3 within mitochondria and reduced mitochondrial function in a non-transcriptional manner, as shown by co-treatment with actinomycin. Treatment with the small molecule bryostatin-1 or hepatocyte growth factor (HGF), which indirectly activate S727-STAT3, preserved mitochondrial function during FAK inhibition, but failed in the presence of the STAT3 inhibitor. FAK inhibition induced loss of mitochondrial membrane potential, which was counteracted by bryostatin, and increased superoxide and hydrogen peroxide production. Bryostatin and HGF reduced the substantial cell death caused by FAK inhibition over a 24 h period. Conclusion These data suggest that extracellular matrix molecules promote STAT3-dependent mitochondrial function and cell survival through integrin-FAK signaling. We furthermore show a new treatment strategy for cell survival using S727-STAT3 activators.
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Affiliation(s)
- Nishant P Visavadiya
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Building 178, Maple Ave, PO Box 70582, Johnson City, TN37614, USA
| | - Matthew P Keasey
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Building 178, Maple Ave, PO Box 70582, Johnson City, TN37614, USA
| | - Vladislav Razskazovskiy
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Building 178, Maple Ave, PO Box 70582, Johnson City, TN37614, USA
| | - Kalpita Banerjee
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Building 178, Maple Ave, PO Box 70582, Johnson City, TN37614, USA
| | - Cuihong Jia
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Building 178, Maple Ave, PO Box 70582, Johnson City, TN37614, USA
| | - Chiharu Lovins
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Building 178, Maple Ave, PO Box 70582, Johnson City, TN37614, USA
| | - Gary L Wright
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Building 178, Maple Ave, PO Box 70582, Johnson City, TN37614, USA
| | - Theo Hagg
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Building 178, Maple Ave, PO Box 70582, Johnson City, TN37614, USA.
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13
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Plani-Lam JHC, Slavova-Azmanova NS, Kucera N, Louw A, Satiaputra J, Singer P, Lam KP, Hibbs ML, Ingley E. Csk-binding protein controls red blood cell development via regulation of Lyn tyrosine kinase activity. Exp Hematol 2016; 46:70-82.e10. [PMID: 27751872 DOI: 10.1016/j.exphem.2016.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 09/30/2016] [Accepted: 10/01/2016] [Indexed: 11/29/2022]
Abstract
Erythropoiesis is controlled principally through erythropoietin (Epo) receptor signaling, which involves Janus kinase 2 (JAK2) and Lyn tyrosine kinase, both of which are important for regulating red blood cell (RBC) development. Negative regulation of Lyn involves C-Src kinase (Csk)-mediated phosphorylation of its C-terminal tyrosine, which is facilitated by the transmembrane adaptor Csk-binding protein (Cbp). Although Cbp has significant functions in controlling Lyn levels and activity in erythroid cells in vitro, its importance to primary erythroid cell development and signaling has remained unclear. To address this, we assessed the consequence of loss of Cbp on the erythroid compartment in vivo and whether Epo-responsive cells isolated from Cbp-knockout mice exhibited altered signaling. Our data show that male Cbp-/- mice display a modest but significant alteration to late erythroid development in bone marrow with evidence of increased erythrocytes in the spleen, whereas female Cbp-/- mice exhibit a moderate elevation in early erythroid progenitors (not seen in male mice) that does not influence the later steps in RBC development. In isolated primary erythroid cells and cell lines generated from Cbp-/- mice, survival signaling through Lyn/Akt/FoxO3 was elevated, resulting in sustained viability during differentiation. The high Akt activity disrupted GAB2/SHP-2 feedback inhibition of Lyn; however, the elevated Lyn activity also increased inhibitory signaling via SHP-1 to restrict the Erk1/2 pathway. Interestingly, whereas loss of Cbp led to mild changes to late RBC development in male mice, this was not apparent in female Cbp-/- mice, possibly due to their elevated estrogen, which is known to facilitate early progenitor self-renewal.
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Affiliation(s)
- Janice H C Plani-Lam
- Cell Signalling Group, Laboratory for Cancer Medicine, Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, WA, Australia
| | - Neli S Slavova-Azmanova
- Cell Signalling Group, Laboratory for Cancer Medicine, Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, WA, Australia
| | - Nicole Kucera
- Cell Signalling Group, Laboratory for Cancer Medicine, Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, WA, Australia
| | - Alison Louw
- Cell Signalling Group, Laboratory for Cancer Medicine, Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, WA, Australia
| | - Jiulia Satiaputra
- Cell Signalling Group, Laboratory for Cancer Medicine, Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, WA, Australia
| | - Peter Singer
- Laboratory of Immunology, Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore, Singapore
| | - Kong-Peng Lam
- Laboratory of Immunology, Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore, Singapore
| | - Margaret L Hibbs
- Leukocyte Signalling Laboratory, Department of Immunology, Alfred Medical Research and Education Precinct, Monash University, Melbourne, VIC, Australia
| | - Evan Ingley
- Cell Signalling Group, Laboratory for Cancer Medicine, Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, WA, Australia.
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14
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Erythropoietin Pathway: A Potential Target for the Treatment of Depression. Int J Mol Sci 2016; 17:ijms17050677. [PMID: 27164096 PMCID: PMC4881503 DOI: 10.3390/ijms17050677] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 04/05/2016] [Accepted: 04/27/2016] [Indexed: 12/21/2022] Open
Abstract
During the past decade, accumulating evidence from both clinical and experimental studies has indicated that erythropoietin may have antidepressant effects. In addition to the kidney and liver, many organs have been identified as secretory tissues for erythropoietin, including the brain. Its receptor is expressed in cerebral and spinal cord neurons, the hypothalamus, hippocampus, neocortex, dorsal root ganglia, nerve axons, and Schwann cells. These findings may highlight new functions for erythropoietin, which was originally considered to play a crucial role in the progress of erythroid differentiation. Erythropoietin and its receptor signaling through JAK2 activate multiple downstream signaling pathways including STAT5, PI3K/Akt, NF-κB, and MAPK. These factors may play an important role in inflammation and neuroprogression in the nervous system. This is particularly true for the hippocampus, which is possibly related to learning, memory, neurocognitive deficits and mood alterations. Thus, the influence of erythropoietin on the downstream pathways known to be involved in the treatment of depression makes the erythropoietin-related pathway an attractive target for the development of new therapeutic approaches. Focusing on erythropoietin may help us understand the pathogenic mechanisms of depression and the molecular basis of its treatment.
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15
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Yang X, Friedl A. A positive feedback loop between prolactin and STAT5 promotes angiogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 846:265-80. [PMID: 25472543 DOI: 10.1007/978-3-319-12114-7_12] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The signal transduction events that orchestrate cellular activities required for angiogenesis remain incompletely understood. We and others recently described that proangiogenic mediators such as fibroblast growth factors can activate members of the signal transducers and activators of transcription (STAT) family. STAT5 activation is necessary and sufficient to induce migration, invasion and tube formation of endothelial cells. STAT5 effects on endothelial cells require the secretion of the prolactin (PRL) family member proliferin-1 (PLF1) in mice and PRL in humans. In human endothelial cells, PRL activates the PRL receptor (PRLR) resulting in MAPK and STAT5 activation, thus closing a positive feedback loop. In vivo, endothelial cell-derived PRL is expected to combine with PRL of tumor cell and pituitary origin to raise the concentration of this polypeptide hormone in the tumor microenvironment. Thus, PRL may stimulate tumor angiogenesis via autocrine, paracrine, and endocrine pathways. The disruption of tumor angiogenesis by interfering with PRL signaling may offer an attractive target for therapeutic intervention.
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Affiliation(s)
- Xinhai Yang
- Department of Pathology and Laboratory Medicine, University of Wisconsin, 6051 WIMR, MC-2275, 1111 Highland Avenue, 53705, Madison, WI, USA,
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16
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Schnöder TM, Arreba-Tutusaus P, Griehl I, Bullinger L, Buschbeck M, Lane SW, Döhner K, Plass C, Lipka DB, Heidel FH, Fischer T. Epo-induced erythroid maturation is dependent on Plcγ1 signaling. Cell Death Differ 2014; 22:974-85. [PMID: 25394487 DOI: 10.1038/cdd.2014.186] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 09/18/2014] [Accepted: 10/06/2014] [Indexed: 12/22/2022] Open
Abstract
Erythropoiesis is a tightly regulated process. Development of red blood cells occurs through differentiation of hematopoietic stem cells (HSCs) into more committed progenitors and finally into erythrocytes. Binding of erythropoietin (Epo) to its receptor (EpoR) is required for erythropoiesis as it promotes survival and late maturation of erythroid progenitors. In vivo and in vitro studies have highlighted the requirement of EpoR signaling through Janus kinase 2 (Jak2) tyrosine kinase and Stat5a/b as a central pathway. Here, we demonstrate that phospholipase C gamma 1 (Plcγ1) is activated downstream of EpoR-Jak2 independently of Stat5. Plcγ1-deficient pro-erythroblasts and erythroid progenitors exhibited strong impairment in differentiation and colony-forming potential. In vivo, suppression of Plcγ1 in immunophenotypically defined HSCs (Lin(-)Sca1(+)KIT(+)CD48(-)CD150(+)) severely reduced erythroid development. To identify Plcγ1 effector molecules involved in regulation of erythroid differentiation, we assessed changes occurring at the global transcriptional and DNA methylation level after inactivation of Plcγ1. The top common downstream effector was H2afy2, which encodes for the histone variant macroH2A2 (mH2A2). Inactivation of mH2A2 expression recapitulated the effects of Plcγ1 depletion on erythroid maturation. Taken together, our findings identify Plcγ1 and its downstream target mH2A2, as a 'non-canonical' Epo signaling pathway essential for erythroid differentiation.
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Affiliation(s)
- T M Schnöder
- Department of Hematology and Oncology, Center for Internal Medicine, Otto-von-Guericke University Medical Center, Magdeburg, Germany
| | - P Arreba-Tutusaus
- Department of Hematology and Oncology, Center for Internal Medicine, Otto-von-Guericke University Medical Center, Magdeburg, Germany
| | - I Griehl
- Department of Hematology and Oncology, Center for Internal Medicine, Otto-von-Guericke University Medical Center, Magdeburg, Germany
| | - L Bullinger
- Internal Medicine III, Department of Hematology/Oncology, University Hospital Ulm, Ulm, Germany
| | - M Buschbeck
- Institute of Predictive and Personalized Medicine of Cancer (IMPPC), Campus Can Ruti, Badalona, Spain
| | - S W Lane
- Division of Immunology, QIMR Berghofer Medical Research Institute, Herston, Brisbane, Australia
| | - K Döhner
- Internal Medicine III, Department of Hematology/Oncology, University Hospital Ulm, Ulm, Germany
| | - C Plass
- Division of Epigenomics and Cancer Risk Factors (C010), German Cancer Research Center, Heidelberg, Germany
| | - D B Lipka
- 1] Department of Hematology and Oncology, Center for Internal Medicine, Otto-von-Guericke University Medical Center, Magdeburg, Germany [2] Division of Epigenomics and Cancer Risk Factors (C010), German Cancer Research Center, Heidelberg, Germany
| | - F H Heidel
- Department of Hematology and Oncology, Center for Internal Medicine, Otto-von-Guericke University Medical Center, Magdeburg, Germany
| | - T Fischer
- Department of Hematology and Oncology, Center for Internal Medicine, Otto-von-Guericke University Medical Center, Magdeburg, Germany
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17
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Lyn kinase plays important roles in erythroid expansion, maturation and erythropoietin receptor signalling by regulating inhibitory signalling pathways that control survival. Biochem J 2014; 459:455-66. [DOI: 10.1042/bj20130903] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In erythroid cells both positive viability signals and feedback inhibitory signalling require the Src family kinase Lyn, influencing cell survival and their ability to differentiate. This illustrates that Lyn is critical for normal erythropoiesis and erythroid cell development.
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18
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García S, Krausz S, Ambarus CA, Fernández BM, Hartkamp LM, van Es IE, Hamann J, Baeten DL, Tak PP, Reedquist KA. Tie2 signaling cooperates with TNF to promote the pro-inflammatory activation of human macrophages independently of macrophage functional phenotype. PLoS One 2014; 9:e82088. [PMID: 24404127 PMCID: PMC3880273 DOI: 10.1371/journal.pone.0082088] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 10/27/2013] [Indexed: 01/28/2023] Open
Abstract
Angiopoietin (Ang) -1 and -2 and their receptor Tie2 play critical roles in regulating angiogenic processes during development, homeostasis, tumorigenesis, inflammation and tissue repair. Tie2 signaling is best characterized in endothelial cells, but a subset of human and murine circulating monocytes/macrophages essential to solid tumor formation express Tie2 and display immunosuppressive properties consistent with M2 macrophage polarization. However, we have recently shown that Tie2 is strongly activated in pro-inflammatory macrophages present in rheumatoid arthritis patient synovial tissue. Here we examined the relationship between Tie2 expression and function during human macrophage polarization. Tie2 expression was observed under all polarization conditions, but was highest in IFN-γ and IL-10 –differentiated macrophages. While TNF enhanced expression of a common restricted set of genes involved in angiogenesis and inflammation in GM-CSF, IFN-γ and IL-10 –differentiated macrophages, expression of multiple chemokines and cytokines, including CXCL3, CXCL5, CXCL8, IL6, and IL12B was further augmented in the presence of Ang-1 and Ang-2, via Tie2 activation of JAK/STAT signaling. Conditioned medium from macrophages stimulated with Ang-1 or Ang-2 in combination with TNF, sustained monocyte recruitment. Our findings suggest a general role for Tie2 in cooperatively promoting the inflammatory activation of macrophages, independently of polarization conditions.
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Affiliation(s)
- Samuel García
- Department of Experimental Immunology, University of Amsterdam, Amsterdam, the Netherlands
- Department of Clinical Immunology and Rheumatology, University of Amsterdam, Amsterdam, the Netherlands
| | - Sarah Krausz
- Department of Experimental Immunology, University of Amsterdam, Amsterdam, the Netherlands
- Department of Clinical Immunology and Rheumatology, University of Amsterdam, Amsterdam, the Netherlands
| | - Carmen A. Ambarus
- Department of Experimental Immunology, University of Amsterdam, Amsterdam, the Netherlands
- Department of Clinical Immunology and Rheumatology, University of Amsterdam, Amsterdam, the Netherlands
| | - Beatriz Malvar Fernández
- Department of Experimental Immunology, University of Amsterdam, Amsterdam, the Netherlands
- Department of Clinical Immunology and Rheumatology, University of Amsterdam, Amsterdam, the Netherlands
| | - Linda M. Hartkamp
- Department of Experimental Immunology, University of Amsterdam, Amsterdam, the Netherlands
- Department of Clinical Immunology and Rheumatology, University of Amsterdam, Amsterdam, the Netherlands
| | - Inge E. van Es
- Department of Experimental Immunology, University of Amsterdam, Amsterdam, the Netherlands
- Department of Clinical Immunology and Rheumatology, University of Amsterdam, Amsterdam, the Netherlands
| | - Jörg Hamann
- Department of Experimental Immunology, University of Amsterdam, Amsterdam, the Netherlands
| | - Dominique L. Baeten
- Department of Experimental Immunology, University of Amsterdam, Amsterdam, the Netherlands
- Department of Clinical Immunology and Rheumatology, University of Amsterdam, Amsterdam, the Netherlands
| | - Paul P. Tak
- Department of Clinical Immunology and Rheumatology, University of Amsterdam, Amsterdam, the Netherlands
| | - Kris A. Reedquist
- Department of Experimental Immunology, University of Amsterdam, Amsterdam, the Netherlands
- Department of Clinical Immunology and Rheumatology, University of Amsterdam, Amsterdam, the Netherlands
- * E-mail:
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19
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Combined inhibition of PI3K and activation of MAPK p38 signaling pathways trigger erythroid alternative splicing switch of 4.1R pre-mRNA in DMSO-induced erythroleukemia cells. Cell Signal 2013; 25:2453-61. [PMID: 23993958 DOI: 10.1016/j.cellsig.2013.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 08/23/2013] [Indexed: 01/09/2023]
Abstract
There is increasing evidence showing that many extracellular cues modulate pre-mRNA alternative splicing, through different signaling pathways. We here show that 4.1R exon 16 splicing is altered in response to specific signals. The switch from erythroblastic isoform lacking exon 16 to mature erythrocytic isoform containing this exon is tightly regulated during late erythroid differentiation, and blocage of this splicing switch in erythroleukemia cells is seen as a consequence of the deregulation of important regulatory pathways. We support that combined inhibition of PI3K and activation of p38 signaling pathways impinge on erythroid 4.1R pre-mRNA alternative splicing switch, and on cell differentiation as witnessed by hemoglobin production. By contrast, MEK/ERK signaling appeared not to affect neither cell hemoglobin production nor erythroid 4.1R pre-mRNA splicing. We also found that the signal-induced alternative splicing is not typically distinctive of EPO-non-responsive cells, but operates in EPO-responsive cells as well. Pre-mRNA splicing is a major regulatory mechanism at the crossroad between transcription and translation. We here provide evidence that inhibition of PI3K activates the splicing switch in a promoter-dependent manner, whereas p38 activation induces this event in a promoter-independent fashion. Our data further support that constitutive activation of EPO-R by the viral protein gp55 and the short form of the tyrosine kinase receptor Stk, transduces PI3K proliferation signal, but not MAPK p38 differentiation signal. Concurrently, this work lend credence to the concept that DMSO triggers transient activation of p38 signaling and irreversible inhibition of PI3K/AKT signaling pathway, hence uncovering an old conundrum regarding the mechanism by which DMSO induces erythroleukemia cell differentiation.
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20
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Pallet N, Rabant M, Legendre C, Martinez F, Choukroun G. The nephroprotective properties of recombinant human erythropoietin in kidney transplantation: experimental facts and clinical proofs. Am J Transplant 2012; 12:3184-90. [PMID: 23057777 DOI: 10.1111/j.1600-6143.2012.04287.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Adaptive responses to hypoxia, including hypoxia-inducible factor signaling, allow the cell to satisfy its basal metabolic demand and avoid death, but these responses can also be deleterious by promoting inflammation, cell dedifferentiation and fibrogenesis. Therefore, targeting hypoxia constitutes a promising therapeutic avenue. Recombinant human erythropoietin (rhEPO) appeared as a good candidate therapy because its hematopoietic properties could reverse anemia, and its tissue-protective properties could reduce cell death and limit maladaptive cellular responses to hypoxia. Despite experimental evidence on the nephroprotecive properties of rhEPO, recent clinical trials provided evidence that rhEPO was ineffective in preventing delayed graft function after ischemic acute injury but that the normalization of hemoglobin values preserved kidney function deterioration and reduced graft loss. Our aim here is to provide a survey of the rationale for evaluating the administration of rhEPO in the setting of kidney transplantation. We will discuss the intriguing findings that emerged from the clinical trials and the discrepancies between promising experimental results and negative clinical studies, as well as the differences in terms of the benefits and safety profiles of the normalization of hemoglobin values in chronic kidney disease patients and kidney transplant patients.
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Affiliation(s)
- N Pallet
- INSERM U775, Centre Universitaire des Saints Pères, et Université Paris Descartes, Paris, France.
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21
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Javadi M, Hofstätter E, Stickle N, Beattie BK, Jaster R, Carter-Su C, Barber DL. The SH2B1 adaptor protein associates with a proximal region of the erythropoietin receptor. J Biol Chem 2012; 287:26223-34. [PMID: 22669948 DOI: 10.1074/jbc.m112.382721] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Gene targeting experiments have shown that the cytokine erythropoietin (EPO), its cognate erythropoietin receptor (EPO-R), and associated Janus tyrosine kinase, JAK2, are all essential for erythropoiesis. Structural-functional and murine knock-in experiments have suggested that EPO-R Tyr-343 is important in EPO-mediated mitogenesis. Although Stat5 binds to EPO-R phosphotyrosine 343, the initial Stat5-deficient mice did not have profound erythroid abnormalities suggesting that additional Src homology 2 (SH2) domain-containing effectors may bind to EPO-R Tyr-343 and couple to downstream signaling pathways. We have utilized cloning of ligand target (COLT) screening to demonstrate that EPO-R Tyr(P)-343 and Tyr(P)-401 bind to the SH2 domain-containing adaptor protein SH2B1β. Immunoprecipitation and in vitro mixing experiments reveal that EPO-R binds to SH2B1 in an SH2 domain-dependent manner and that the sequence that confers SH2B1 binding to the EPO-R is pYXXL. Previous studies have shown that SH2B1 binds directly to JAK2, but we show that in hematopoietic cells, SH2B1β preferentially associates with the EPO-R. SH2B1 is capable of constitutive association with EPO-R, which is necessary for its optimal SH2-dependent recruitment to EPO-R-Tyr(P)-343/Tyr(P)-401. We also demonstrate that SH2B1 is responsive to EPO stimulation and becomes phosphorylated, most likely on serines/threonines, in an EPO dose- and time-dependent manner. In the absence of SH2B1, we observe enhanced activation of signaling pathways downstream of the EPO-R, indicating that SH2B1 is a negative regulator of EPO signaling.
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Affiliation(s)
- Mojib Javadi
- Ontario Cancer Institute, Campbell Family Cancer Research Institute, Toronto, Ontario M5G 2M9, Canada
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22
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Shimada K, Ohno Y, Okamatsu-Ogura Y, Suzuki M, Kamikawa A, Terao A, Kimura K. Neuropeptide Y activates phosphorylation of ERK and STAT3 in stromal vascular cells from brown adipose tissue, but fails to affect thermogenic function of brown adipocytes. Peptides 2012; 34:336-42. [PMID: 22374387 DOI: 10.1016/j.peptides.2012.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 02/16/2012] [Accepted: 02/16/2012] [Indexed: 12/22/2022]
Abstract
The thermogenic function of brown adipose tissue (BAT) is increased by norepinephrine (NE) released from sympathetic nerve endings, but the roles of NPY released along with NE are poorly elucidated. Here, we examined effect of NPY on basal and NE-enhanced thermogenesis in isolated brown adipocytes that express Y1 and Y5 receptor mRNA. Treatment of cells with NPY did not influence the basal and NE-enhanced rates of oxygen consumption and cAMP accumulation. Treatment with NPY also failed to induce ERK (Thr202/Tyr204) phosphorylation in the brown adipocytes. In contrast, treatment with NPY increased ERK phosphorylation in cultured stromal vascular cells from the BAT that express Y1 receptor mRNA. In the latter treatment with NPY also increased STAT3 (Ser727) phosphorylation. These results suggest that NPY mainly acts on stromal vascular cells in BAT and plays roles in the regulation of their gene transcription through ERK and STAT3 pathways, while NPY does not affect the thermogenic function of brown adipocytes.
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Affiliation(s)
- Kohei Shimada
- Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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Nairz M, Sonnweber T, Schroll A, Theurl I, Weiss G. The pleiotropic effects of erythropoietin in infection and inflammation. Microbes Infect 2011; 14:238-46. [PMID: 22094132 PMCID: PMC3278592 DOI: 10.1016/j.micinf.2011.10.005] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 10/18/2011] [Indexed: 01/30/2023]
Abstract
Erythropoietin (EPO) is a multi-functional cytokine, which exerts erythropoietic effects but also carries anti-apoptotic and immune-modulatory activities upon binding to two distinct receptors which are expressed on erythroid, parenchymal and immune cells, respectively. Whereas EPO ameliorates hemolytic anemia in malaria or trypanosomiasis and improves the course of autoimmune diseases such as inflammatory bowel disease or autoimmune encephalomyelitis, it deleteriously inhibits macrophage functions in Salmonella infection in animal models. Thus, the specific modulation of extra-erythropoietic EPO activity forms an attractive therapeutic target in infection and inflammation.
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Affiliation(s)
| | | | | | | | - Günter Weiss
- Corresponding author. Tel.: +43 512 504 23255; fax: +43 512 504 25607.
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Chateauvieux S, Grigorakaki C, Morceau F, Dicato M, Diederich M. Erythropoietin, erythropoiesis and beyond. Biochem Pharmacol 2011; 82:1291-303. [DOI: 10.1016/j.bcp.2011.06.045] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 06/28/2011] [Accepted: 06/29/2011] [Indexed: 12/21/2022]
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Talbot AL, Bullock GC, Delehanty LL, Sattler M, Zhao ZJ, Goldfarb AN. Aconitase regulation of erythropoiesis correlates with a novel licensing function in erythropoietin-induced ERK signaling. PLoS One 2011; 6:e23850. [PMID: 21887333 PMCID: PMC3161794 DOI: 10.1371/journal.pone.0023850] [Citation(s) in RCA: 12] [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: 03/07/2011] [Accepted: 07/26/2011] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Erythroid development requires the action of erythropoietin (EPO) on committed progenitors to match red cell output to demand. In this process, iron acts as a critical cofactor, with iron deficiency blunting EPO-responsiveness of erythroid progenitors. Aconitase enzymes have recently been identified as possible signal integration elements that couple erythropoiesis with iron availability. In the current study, a regulatory role for aconitase during erythropoiesis was ascertained using a direct inhibitory strategy. METHODOLOGY/PRINCIPAL FINDINGS In C57BL/6 mice, infusion of an aconitase active-site inhibitor caused a hypoplastic anemia and suppressed responsiveness to hemolytic challenge. In a murine model of polycythemia vera, aconitase inhibition rapidly normalized red cell counts, but did not perturb other lineages. In primary erythroid progenitor cultures, aconitase inhibition impaired proliferation and maturation but had no effect on viability or ATP levels. This inhibition correlated with a blockade in EPO signal transmission specifically via ERK, with preservation of JAK2-STAT5 and Akt activation. Correspondingly, a physical interaction between ERK and mitochondrial aconitase was identified and found to be sensitive to aconitase inhibition. CONCLUSIONS/SIGNIFICANCE Direct aconitase inhibition interferes with erythropoiesis in vivo and in vitro, confirming a lineage-selective regulatory role involving its enzymatic activity. This inhibition spares metabolic function but impedes EPO-induced ERK signaling and disturbs a newly identified ERK-aconitase physical interaction. We propose a model in which aconitase functions as a licensing factor in ERK-dependent proliferation and differentiation, thereby providing a regulatory input for iron in EPO-dependent erythropoiesis. Directly targeting aconitase may provide an alternative to phlebotomy in the treatment of polycythemia vera.
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Affiliation(s)
- Anne-Laure Talbot
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Grant C. Bullock
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Lorrie L. Delehanty
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Martin Sattler
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Zhizhuang Joe Zhao
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Adam N. Goldfarb
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
- * E-mail:
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Yang B, Singh S, Bressani R, Kanmogne GD. Cross-talk between STAT1 and PI3K/AKT signaling in HIV-1-induced blood-brain barrier dysfunction: role of CCR5 and implications for viral neuropathogenesis. J Neurosci Res 2011; 88:3090-101. [PMID: 20568281 DOI: 10.1002/jnr.22458] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
How neuroinflammation affects signaling pathways leading to human blood-brain barrier (BBB) dysfunction during HIV-1 infection is incompletely understood. We previously demonstrated that signal transducers and activators of transcription-1 (STAT1) signaling is involved in HIV-1 induced BBB damage and is relevant to viral neuropathogenesis. The objective of this study was to delineate the signaling pathways upstream and downstream of STAT1 involved in HIV-1-induced endothelial dysfunction. We show that HIV-1 activation of STAT1 and STAT3 in human brain microvascular endothelial cells (HBMEC) is associated with induction of promoter activity of the interferon-stimulated response element (ISRE)/interferon-γ-activated sequence (GAS). The STAT1 inhibitor fludarabine diminished HIV-1-induced ISRE/GAS promoter activity. CCR5 neutralizing antibodies and the phosphoinositide-3-kinase (PI3K) inhibitor LY-294002 diminished HIV-1-induced phosphorylation of STAT1 and STAT3, significantly diminished HIV-1-induced ISRE/GAS promoter activity, and diminished virus-induced monocyte adhesion and transendothelial migration. HIV-1 infection did not phosphorylate janus kinases but induced activation of the phosphoinositide-dependent kinase-1 (PDK1) and the serine-threonine protein kinase AKT, both downstream effectors of PI3K. CCR5 antibodies also diminished virus-induced phosphorylation ofPDK1 and AKT. These results suggest that the chemokine receptor CCR5 is partially involved in HIV-1 binding to HBMEC and show cross-talk between STAT1 and PI3K pathways in HIV-1-induced BBB dysfunction.
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Affiliation(s)
- Bo Yang
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nerbraska, USA
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Qian Q, Qian H, Zhang X, Zhu W, Yan Y, Ye S, Peng X, Li W, Xu Z, Sun L, Xu W. 5-Azacytidine induces cardiac differentiation of human umbilical cord-derived mesenchymal stem cells by activating extracellular regulated kinase. Stem Cells Dev 2011; 21:67-75. [PMID: 21476855 DOI: 10.1089/scd.2010.0519] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
5-Azacytidine (5-Aza) induces differentiation of mesenchymal stem cells (MSCs) into cardiomyocytes. However, the underlying mechanisms are not well understood. Our previous work showed that 5-Aza induces human bone marrow-derived MSCs to differentiate into cardiomyocytes. Here, we demonstrated that 5-Aza induced cardiac differentiation of human umbilical cord-derived MSCs (hucMSCs) and explored the potential signaling pathway. Our results showed that hucMSCs had cardiomyocyte phenotypes after 5-Aza treatment. In addition, myogenic cells differentiated from hucMSCs were positive for mRNA and protein of desmin, β-myosin heavy chain, cardiac troponin T, A-type natriuretic peptide, and Nkx2.5. Human diploid lung fibroblasts treated with 5-Aza expressed no cardiac-specific genes. 5-Aza did not induce hucMSCs to differentiate into osteoblasts. Further study revealed that 5-Aza treatment activated extracellular signal related kinases (ERK) in hucMSCs, but protein kinase C showed no response to 5-Aza administration. U0126, a specific inhibitor of ERK, could inhibit 5-Aza-induced expression of cardiac-specific genes and proteins in hucMSCs. Increased phosphorylation of signal transducers and activators of transcription 3, and up-regulation of myocyte enhancer-binding factor-2c and myogenic differentiation antigen in 5-Aza-treated hucMSCs were also suppressed by U0126. Taken together, these results suggested that sustained activation of ERK by 5-Aza contributed to the induction of the differentiation of hucMSCs into cardiomyocytes in vitro.
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Affiliation(s)
- Qian Qian
- School of Medical Science and Laboratory Medicine, Jiangsu University, Zhenjiang, People's Republic of China
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STAT3 and hypoxia induced proteins--HIF-1alpha, EPO and EPOR in relation with Bax and Bcl-xL in nodal metastases of ductal breast cancers. Folia Histochem Cytobiol 2010; 47:425-30. [PMID: 20164027 DOI: 10.2478/v10042-009-0099-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
STAT3 contributes to increase of EPO expression which is also HIF-1 dependent. EPO receptor activates STAT3. Expressions of STAT3 and hypoxia induced proteins: HIF-1, EPO and EPOR show mutual correlations in primary ductal breast cancers, which suggest co-operation among these proteins. Moreover, EPO-EPOR signaling was reported to mediate cell survival by targeting Bcl-xL in competition with Bax-dependent apoptosis. Our present study was focused on immunohistochemical evaluation of STAT3, HIF-1alpha, EPO and EPOR in relation to apoptosis regulators, Bax and Bcl-xL in 39 metastases of ductal breast cancers to lymph nodes. The proteins were abundantly expressed by cancer cells. HIF-1alpha correlated with EPOR in all and in chemotherapy treated metastases (r=0.428, p=0.007 and r=0.462, p=0.040, respectively). HIF-1 associated significantly with EPO in chemotherapy spared metastases (r=0.549, p=0.015) and comparison between those proteins almost reached statistical significance in entire number of metastatic breast cancers (r=0.309, p=0.056). Metastases from T2 primary tumors had significantly higher expressions of HIF-1alpha, EPO and EPOR compared to T1 originating metastases (p=0.020, p=0.028, p=0.021, respectively). Bax correlated with EPO and EPOR in all studied nodal metastases (r=0.449, p=0.006 and r=0.421, p=0.011, respectively) and so did Bcl-xL with HIF-1alpha (r=0.440, p=0.007), EPO and EPOR (r=0.383, p=0.021, r=0.495, p=0.002, respectively). Metastatic breast cancers seem to be areas of intensive signaling by STAT3, HIF-1, EPO and EPOR. Strong Bax and Bcl-xL labeling reflects accelerated cell turnover in nodal metastases. By means of association with Bcl-xL, HIF-1alpha, EPO and EPOR could favor growth of nodal metastases and survival of breast cancers cells.
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Insertion of an NPVY sequence into the cytosolic domain of the erythropoietin receptor selectively affects erythropoietin-mediated signalling and function. Biochem J 2010; 427:305-12. [DOI: 10.1042/bj20091951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
EPO (erythropoietin), the major hormone regulating erythropoiesis, functions via activation of its cell-surface receptor (EPO-R) present on erythroid progenitor cells. One of the most striking properties of EPO-R is its low expression on the cell surface, as opposed to its high intracellular levels. The low cell-surface expression of EPO-R may thus limit the efficacy of EPO that is routinely used to treat primary and secondary anaemia. In a recent study [Nahari, Barzilay, Hirschberg and Neumann (2008) Biochem. J. 410, 409–416] we have shown that insertion of an NPVY sequence into the intracellular domain of EPO-R increases its cell-surface expression. In the present study we demonstrate that this NPVY EPO-R insert has a selective effect on EPO-mediated downstream signalling in Ba/F3 cells expressing this receptor (NPVY-EPO-R). This is monitored by increased phosphorylation of the NPVY-EPO-R (on Tyr479), Akt, JAK2 (Janus kinase 2) and ERK1/2 (extracellular-signal-regulated kinase 1/2), but not STAT5 (signal transducer and activator of transcription 5), as compared with cells expressing wild-type EPO-R. This enhanced signalling is reflected in augmented proliferation at low EPO levels (0.05 units/ml) and protection against etoposide-induced apoptosis. Increased cell-surface levels of NPVY-EPO-R are most probably not sufficient to mediate these effects as the A234E-EPO-R mutant that is expressed at high cell-surface levels does not confer an augmented response to EPO. Taken together, we demonstrate that insertion of an NPVY sequence into the cytosolic domain of the EPO-R confers not only improved maturation, but also selectively affects EPO-mediated signalling resulting in an improved responsiveness to EPO reflected in cell proliferation and protection against apoptosis.
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Lo Nigro C, Maffi M, Fischel JL, Monteverde M, Catarsi P, Tonissi F, Lattanzio L, Riba M, Etienne-Grimaldi MC, Formento P, Milano G, Merlano M. Impact of erythropoietin on the effects of irradiation under hypoxia. J Cancer Res Clin Oncol 2009; 135:1615-23. [DOI: 10.1007/s00432-009-0609-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Accepted: 05/19/2009] [Indexed: 11/29/2022]
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Cisplatin-induced hair cell death requires STAT1 and is attenuated by epigallocatechin gallate. J Neurosci 2009; 29:3843-51. [PMID: 19321781 DOI: 10.1523/jneurosci.5842-08.2009] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cisplatin is a chemotherapy drug that frequently causes auditory impairment due to the death of mechanosensory hair cells. Cisplatin ototoxicity may result from oxidative stress, DNA damage, and inflammatory cytokines. The transcription factor STAT1, an important mediator of cell death, can regulate all of these processes in other cell types. We used cultured utricles from mature Swiss Webster mice to investigate the role of STAT1 in cisplatin-induced hair cell death. We show that STAT1 phosphorylation is an early event in both hair cells and support cells after exposure of utricles to cisplatin. STAT1 phosphorylation peaked after 4 h of cisplatin exposure and returned to control levels by 8 h of exposure. The STAT1 inhibitor epigallocatechin gallate (EGCG) attenuated STAT1 phosphorylation in cisplatin-treated utricles and resulted in concentration-dependent increases in hair cell survival at 24 h postexposure. Furthermore, we show that utricular hair cells from STAT1-deficient mice are resistant to cisplatin toxicity. EGCG failed to provide additional protection from cisplatin in STAT1-deficient mice, further supporting the hypothesis that the protective effects of EGCG are due to its inhibition of STAT1. Treatment with IFN-gamma, which also causes STAT1 activation, also induced hair cell death in wild-type but not STAT1-deficient mice. These results show that STAT1 is required for maximal cisplatin-induced hair cell death in the mouse utricle and suggest that treatment with EGCG may be a useful strategy for prevention of cisplatin ototoxicity.
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Brown S, Zeidler MP. Unphosphorylated STATs go nuclear. Curr Opin Genet Dev 2008; 18:455-60. [PMID: 18840523 DOI: 10.1016/j.gde.2008.09.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Revised: 08/22/2008] [Accepted: 09/05/2008] [Indexed: 10/21/2022]
Abstract
The JAK/STAT signal transduction pathway has traditionally been viewed as a cytokine-stimulated activator of gene expression consisting of a straightforward receptor/JAK kinase/STAT transcription factor cascade. Recent studies in Drosophila, have, however consistently identified a range of chromatin-remodelling factors as regulators of in vivo JAK/STAT signalling. Now, the detailed analysis of one of these, heterochromatin protein 1 (HP1), has provided an insight into an unexpected non-canonical in vivo role for STAT. In this model, unphosphorylated STATs associate with and maintain the stability of transcriptionally repressed heterochromatin--an effect countered by the recruitment of STAT to the canonical pathway. We examine the background of this new model and its implications for JAK/STAT pathway requirements in stem cell maintenance and cancer.
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Affiliation(s)
- Stephen Brown
- Faculty of Life Science, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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33
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Mao W, Iwai C, Liu J, Sheu SS, Fu M, Liang CS. Darbepoetin alfa exerts a cardioprotective effect in autoimmune cardiomyopathy via reduction of ER stress and activation of the PI3K/Akt and STAT3 pathways. J Mol Cell Cardiol 2008; 45:250-60. [PMID: 18586265 DOI: 10.1016/j.yjmcc.2008.05.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Revised: 05/04/2008] [Accepted: 05/18/2008] [Indexed: 11/15/2022]
Abstract
Dilated human cardiomyopathy is associated with suppression of the prosurvival phosphatidylinositol-3-kinase (PI3K)/Akt and STAT3 pathways. The present study was carried out to determine if restoration of the PI3K/Akt and STAT3 activity by darbepoetin alfa improved cardiac function or reduced cardiomyocyte apoptosis in rabbit autoimmune cardiomyopathy induced by a peptide corresponding to the second extracellular loop of the ss(1)-adrenergic receptor (ss(1)-EC(II)). We found that ss(1)-EC(II) immunization produced progressive LV dilation, systolic dysfunction and myocyte apoptosis as measured by TUNEL, single-stranded DNA antibody, and active caspase-3. These changes were associated with activation of p38 mitogen-activated protein kinase (MAPK), endoplasmic reticulum stress markers (GRP78 and CHOP), and increased cleavage of procaspase-12, as well as decreased phosphorylation of Akt and STAT3, and decreased Bcl2/Bax ratio. As expected, darbepoetin alfa treatment increased phosphorylation of Akt and STAT3. It also increased the myocardial expression of erythropoietin receptor which was reduced in the failing myocardium, and improved cardiac function in the ss(1)-EC(II)-immunized animals. The latter was associated with reductions of myocyte apoptosis and cleaved caspase-3, as well as reversal of increased phosphorylation of p38-MAPK, increased ER stress, and decline in Bcl2/Bax ratio. The anti-apoptotic effects of darbepoetin alfa via Akt and STAT activation were also demonstrated in cultured cardiomyocytes treated with the anti-ss(1)-EC(II) antibody. These effects of darbepoetin alfa in vitro were prevented by LY294002 and STAT3 peptide inhibitor. Thus, we conclude that darbepoetin alfa improves cardiac function and prevents progression of dilated cardiomyopathy probably by activating the PI3K/Akt and STAT3 pathways and reducing ER stress.
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Affiliation(s)
- Weike Mao
- Cardiology Division, Department of Medicine, University of Rochester Medical Center, Rochester, New York 14642, USA
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Vanhatupa S, Ungureanu D, Paakkunainen M, Silvennoinen O. MAPK-induced Ser727 phosphorylation promotes SUMOylation of STAT1. Biochem J 2007; 409:179-85. [PMID: 17897103 DOI: 10.1042/bj20070620] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
STAT1 (signal transducer and activator of transcription 1) is a critical mediator of IFN-γ (interferon-γ)-induced gene responses, and its function is regulated through phosphorylation of Tyr701 and Ser727. MAPK (mitogen-activated protein kinase) pathways mediate phosphorylation of Ser727 in response to microbial infections, stress stimuli and growth factors. Recently, STAT1 was found to become modified by PIAS (protein inhibitor of activated STAT)-mediated SUMO-1 (small ubiquitin-related modifier-1) conjugation at Lys703, but the regulation of this modification is largely unknown. Here, we have investigated the role of MAPK-induced Ser727 phosphorylation in regulation of STAT1 SUMOylation. Activation of the p38MAPK pathway by upstream activating kinase, MKK6 (MAPK kinase-6) or osmotic stress enhanced the SUMOylation of STAT1, which was counteracted by the p38MAPK inhibitor SB202190 or by dominant-negative p38MAPK. Activation of the ERK1/2 (extracellular-signal-regulated kinase 1/2) pathway by Raf-1 also enhanced Ser727 phosphorylation and SUMOylation of STAT1, and this induction was counteracted by PD98059 inhibitor. Mutation of Ser727 to alanine abolished the p38MAPK-induced SUMOylation. Furthermore, S727D and S727E mutations, which mimic the phosphorylation of Ser727, enhanced the basal SUMOylation of STAT1 and interaction between PIAS1 and STAT1. Taken together, these results identify Ser727 phosphorylation as a regulator of STAT1 SUMOylation and highlight the central role of Ser727 in co-ordination of STAT1 functions in cellular responses.
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Affiliation(s)
- Sari Vanhatupa
- Institute of Medical Technology, University of Tampere, FIN-33014 Tampere, Finland
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35
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36
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Weaver AM, Silva CM. S731 in the transactivation domain modulates STAT5b activity. Biochem Biophys Res Commun 2007; 362:1026-30. [PMID: 17822672 PMCID: PMC2041903 DOI: 10.1016/j.bbrc.2007.08.087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 08/17/2007] [Indexed: 12/25/2022]
Abstract
As mediators of cytokine and growth factor signaling, signal transducers and activators of transcription (STATs) transmit signals from the membrane and cytoplasm to the nucleus. While Y699 phosphorylation is required for STAT5b transcriptional activity, our previous studies show that mutation of two tyrosines in the transactivation domain of STAT5b (Y740/743F) increases Y699 phosphorylation leading to increased transcriptional activity and DNA synthesis in breast cancer cells [A.M. Weaver, C.M. Silva, Modulation of signal transducer and activator of transcription 5b activity in breast cancer cells by mutation of tyrosines within the transactivation domain, Molecular Endocrinology 20 (2006) 2392-2405]. In many instances, phosphorylation of serines in the transactivation domain also modulates STAT5b activity. Here, we demonstrate for the first time that EGF stimulation enhances S731 phosphorylation. Furthermore, we show that the increased activity of the Y740/743F STAT5b mutant requires S731. As STAT5b is implicated in several cancers, understanding how its activity is regulated through tyrosine and serine phosphorylation is vital for the development of potential novel cancer therapeutics.
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Affiliation(s)
- Amanda M Weaver
- Department of Medicine and the Cancer Center, University of Virginia, Charlottesville, VA 22908, USA
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Ni S, Zhao C, Feng GS, Paulson RF, Correll PH. A novel Stat3 binding motif in Gab2 mediates transformation of primary hematopoietic cells by the Stk/Ron receptor tyrosine kinase in response to Friend virus infection. Mol Cell Biol 2007; 27:3708-15. [PMID: 17353274 PMCID: PMC1899994 DOI: 10.1128/mcb.01838-06] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Friend erythroleukemia virus has long served as a paradigm for the study of the multistage progression of leukemia. Friend virus infects erythroid progenitor cells, followed by an initial polyclonal expansion of infected cells, which is driven by the activation of a naturally occurring truncated form of the Stk receptor tyrosine kinase (Sf-Stk). Subsequently, the accumulation of additional mutations in p53 and the activation of PU.1 result in full leukemic transformation. The early stages of transformation induced by Friend virus are characterized in vitro by the Epo-independent growth of infected erythroblasts. We have shown previously that this transforming event requires the kinase activity and Grb2 binding site of Sf-Stk and the recruitment of a Grb2/Gab2 complex to Sf-Stk. Here, we demonstrate that Stat3 is required for the Epo-independent growth of Friend virus-infected cells and that the activation of Stat3 by Sf-Stk is mediated by a novel Stat3 binding site in Gab2. These results underscore a central role for Stat3 in hematopoietic transformation and describe a previously unidentified role for Gab2 in the recruitment and activation of Stat3 in response to transforming signals generated by tyrosine kinases.
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Affiliation(s)
- Shuang Ni
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, 115 Henning Building, University Park, PA 16802-3500, USA
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Um M, Gross AW, Lodish HF. A "classical" homodimeric erythropoietin receptor is essential for the antiapoptotic effects of erythropoietin on differentiated neuroblastoma SH-SY5Y and pheochromocytoma PC-12 cells. Cell Signal 2006; 19:634-45. [PMID: 17045782 DOI: 10.1016/j.cellsig.2006.08.014] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Accepted: 08/21/2006] [Indexed: 02/01/2023]
Abstract
The hematopoietic cytokine erythropoietin (Epo) exerts cytoprotective effects on several types of neuronal cells both in vivo and in culture. Detailed molecular mechanisms underlying this phenomenon have not been elucidated and even the identity of the cytoprotective Epo receptors in neuronal cells is controversial. Here we show that Epo prevents staurosporine-induced apoptosis of differentiated human neuroblastoma SH-SY5Y cells, and activates the STAT5, AKT and MAPK signaling pathways. Differentiated SH-SY5Y cells have fewer than 50 high affinity Epo surface binding sites per cell, which could not be detected by standard assays measuring binding of 125I-labeled Epo. However, by measuring endocytosis of 125I-Epo, we could reliably quantify very small numbers of high-affinity Epo surface binding sites. Using SH-SY5Y cells stably expressing an Epo receptor (EpoR) shRNA and thus lacking detectable EpoR expression, we show that high affinity binding of Epo to these neuronal cells is mediated by the hematopoietic EpoR, and that this EpoR is also essential for the antiapoptotic activity of Epo. In contrast, a mutant Epo that has an intact binding site 1 but a non-functional binding site 2 and hence binds only to one cell surface EpoR molecule ("site 2" Epo mutant) displays significantly lower antiapoptotic activity than wild-type Epo. Furthermore, expression of the GM-CSF/IL-3/IL-5 receptor common beta chain, which was proposed to be responsible for the cytoprotective activity of Epo on certain types of neuronal cells, was undetectable in differentiated SH-SY5Y cells. Epo also alleviated staurosporine-induced apoptosis of rat PC-12 pheochromocytoma cells while the R103A "site 2" Epo mutant did not, and we could not detect expression of the common beta chain in PC-12 cells. Together our results indicate that Epo exerts its antiapoptotic effects on differentiated SH-SY5Y and PC-12 cells through the standard stoichiometry of one molecule of Epo binding to two EpoR subunits, comprising the "classical" Epo receptor signaling complex.
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Affiliation(s)
- Moonkyoung Um
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
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Kim SO, Sheikh HI, Ha SD, Martins A, Reid G. G-CSF-mediated inhibition of JNK is a key mechanism for Lactobacillus rhamnosus-induced suppression of TNF production in macrophages. Cell Microbiol 2006; 8:1958-71. [PMID: 16889627 DOI: 10.1111/j.1462-5822.2006.00763.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Lactobacillus rhamnosus is a human commensal with known immunomodulatory properties. To date the mechanism of these immunomodulatory effects is not well understood. To unravel the immunomodulatory signalling mechanism, we investigated the effects of two strains of L. rhamnosus, L. rhamnosus GG and GR-1, in modulating production of tumour necrosis factor-alpha (TNF) in human monocytic cell line THP-1 and mouse macrophages. Live L. rhamnosus GG and GR-1 or their spent culture supernatant induced minuscule amounts of TNF production but large quantities of granulocyte-colony stimulating factor (G-CSF) in macrophages compared with those induced by pathogenic Escherichia coli GR-12 and Enterococcus faecalis. By using neutralizing antibodies and G-CSF receptor knockout mice, we demonstrated that G-CSF secreted from L. rhamnosus GG- and GR-1-exposed macrophages suppressed TNF production induced by E. coli- or lipopolysaccharide-activated macrophages through a paracrine route. The suppression of TNF production by G-CSF was mediated through activation of STAT3 and subsequent inhibition of c-Jun-N-terminal kinases (JNKs). The inhibition of JNK activation required STAT3alpha-mediated de novo protein synthesis. This demonstrates a novel role of G-CSF in L. rhamnosus-triggered anti-inflammatory effects and its mechanism in the suppression of TNF production in macrophages.
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Affiliation(s)
- Sung O Kim
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, N6G 2V4, Canada.
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Fu Z, Huang D, Cai J, Chen Q, Han L, Li B, Wang F, Gao J. Expression changes of ERK1/2, STAT3 and SHP-2 in bone marrow cells from gamma-ray induced leukemia mice. JOURNAL OF RADIATION RESEARCH 2006; 47:121-30. [PMID: 16819138 DOI: 10.1269/jrr.47.121] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The aim is to clarify expression changes of ERK1/2, STAT3 and SHP-2 in bone marrow cells from gamma-ray induced leukemia mice. A mouse model of gamma-ray induced leukemia was produced, and by means of quantitative real-time PCR, immunoprecipitation, Western blotting and electrophoretic mobility shift assays (EMSA), the expression of mRNA and protein, phosphorylation level, and protein activity of ERK1/2, STAT3 and SHP-2 in bone marrow cells were investigated in these mice. The results indicated that mRNA and protein expressions of ERK1/2 were upregulated, with significant increase of phosphorylation level and protein activity, but with insignificant differences in mRNA and protein expressions, phosphorylation level and protein activity of STAT3 and SHP-2 in bone marrow cells from gamma-ray induced leukemia mice compared to the radiation/tumor-free or control mice. It is concluded that in the pathogenesis of gamma-ray induced leukemia in Balb/C mice, activated ERK1/2 pathway may play a role, without involving STAT3 pathway; meanwhile, SHP-2 exerts no regulative effect on pathways of Ras-ERK1/2 and JAK-STAT.
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Affiliation(s)
- Zhichao Fu
- Department of Radiotherapy, General Hospital of Fuzhou Military Command, China
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van der Meer P, Lipsic E, Henning RH, de Boer RA, Suurmeijer AJH, van Veldhuisen DJ, van Gilst WH. Erythropoietin improves left ventricular function and coronary flow in an experimental model of ischemia-reperfusion injury. Eur J Heart Fail 2006; 6:853-9. [PMID: 15556046 DOI: 10.1016/j.ejheart.2004.03.012] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2003] [Revised: 02/03/2004] [Accepted: 03/03/2004] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Recent studies show that erythropoietin (EPO) plays a protective role in brain ischemia. In this condition, administration of EPO protects neurons from ischemic damage. Recently, it has been shown that in patients with chronic heart failure (CHF), EPO treatment improved cardiac function. In the present study we assessed the role of EPO and EPO-receptor (EPO-R) in the heart. METHODS AND RESULTS We studied the presence and functionality of the EPO-R in isolated rat hearts in the Langendorff set-up. Hearts were perfused for 20 min with 10 U/ml EPO or vehicle. Immunohistochemistry revealed the presence of the EPO-R on endothelial cells, fibroblasts and to a lesser extent cardiomyocytes. Furthermore, perfusion with EPO resulted in a 50% increase in the phosphorylated MAP kinases p42/p44. To evaluate the protective role of EPO in cardiac ischemia, we performed low-flow (0.6 ml/min) ischemia/reperfusion experiments in isolated rat hearts. Administration of EPO (10 U/ml) reduced the cellular damage by 56% (P<0.05) during reperfusion, diminished apoptosis by 15% (P<0.05) and resulted in a significantly improved recovery of left ventricular pressure (P=0.02) and coronary flow (P=0.01). CONCLUSION The present data suggest that a functional EPO-R is present in rat adult cardiac tissue and that exogenous EPO administration improves cardiac function after ischemia/reperfusion injury.
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Affiliation(s)
- Peter van der Meer
- Department of Cardiology, University Hospital Groningen, Groningen, The Netherlands
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Um M, Lodish HF. Antiapoptotic effects of erythropoietin in differentiated neuroblastoma SH-SY5Y cells require activation of both the STAT5 and AKT signaling pathways. J Biol Chem 2006; 281:5648-56. [PMID: 16407271 DOI: 10.1074/jbc.m510943200] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The hematopoietic cytokine erythropoietin (Epo) prevents neuronal death during ischemic events in the brain and in neurodegenerative diseases, presumably through its antiapoptotic effects. To explore the role of different signaling pathways in Epo-mediated antiapoptotic effects in differentiated human neuroblastoma SH-SY5Y cells, we employed a prolactin receptor (PrlR)/erythropoietin receptor (EpoR) chimera system, in which binding of prolactin (Prl) to the extracellular domain activates EpoR signaling in the cytosol. On induction of apoptosis by staurosporine, Prl supports survival of the SH-SY5Y cells expressing the wild-type PrlR/EpoR chimera. In these cells Prl treatment strongly activates the STAT5, AKT, and MAPK signaling pathways and induces weak activation of the p65 NF-kappaB factor. Selective mutation of the eight tyrosine residues of the EpoR cytoplasmic domain results in impaired or absent activation of either STAT5 (mutation of Tyr(343)) or AKT (mutation of Tyr(479)) or both (mutation of all eight tyrosine residues). Most interestingly, Prl treatment does not prevent apoptosis in cells expressing mutant PrlR/EpoR chimeras in which either the STAT5 or the AKT signaling pathways are not activated. In contrast, ERK 1/2 is fully activated by all mutant PrlR/EpoR chimeras, comparable with the level seen with the wild-type PrlR/EpoR chimera, implying that activation of the MAPK signaling pathway per se is not sufficient for antiapoptotic activity. Therefore, the antiapoptotic effects of Epo in neuronal cells require the combinatorial activation of multiple signaling pathways, including STAT5, AKT, and potentially MAPK as well, in a manner similar to that observed in hematopoietic cells.
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Affiliation(s)
- Moonkyoung Um
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA
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Desrivières S, Kunz C, Barash I, Vafaizadeh V, Borghouts C, Groner B. The biological functions of the versatile transcription factors STAT3 and STAT5 and new strategies for their targeted inhibition. J Mammary Gland Biol Neoplasia 2006; 11:75-87. [PMID: 16947086 DOI: 10.1007/s10911-006-9014-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Signal transducers and activators of transcription (STATs) comprise a unique family of transcription factors, which transmit the interactions of cytokines, hormones and growth factors with their cell surface receptors into transcriptional programs. The mechanism of STAT activation has been well-established and comprises tyrosine phosphorylation, dimerization, nuclear translocation, binding to specific DNA response elements, recruitment of co-activators or co-repressors and transcriptional induction or repression of target genes. Gene deletion, microarrays, proteomics and chromatin immunoprecipitation experiments have revealed target genes with a broad range of functions regulated by STAT3 and STAT5. In the mammary gland, STAT5-induced genes contribute mainly to the prolactin dependent lobulo-alveolar development, whereas STAT3 induced genes control apoptosis during involution. Crucial effects have also been observed in other tissues. The germ line deletion of STAT3 or STAT5 causes early embryonal or perinatal lethality in mice. STAT5 is also required for proliferation of T- and B-cells and hematopoietic stem cell self-renewal. Deregulated STAT activity is often found associated with tumorigenesis and activated STATs seem to be limiting components in tumor cells. This review summarizes the functions of STAT3 and STAT5 in different cell types and the strategies that are used to counteract their action in tumor cells.
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Affiliation(s)
- Sylvane Desrivières
- Georg-Speyer-Haus, Institute for Biomedical Research, Paul-Ehrlich-Strasse 42, D-60596 Frankfurt am Main, Germany
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Menon MP, Fang J, Wojchowski DM. Core erythropoietin receptor signals for late erythroblast development. Blood 2005; 107:2662-72. [PMID: 16332976 PMCID: PMC1895369 DOI: 10.1182/blood-2005-02-0684] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Critical signals for erythroblast formation are transduced by activated, tyrosine-phosphorylated erythropoietin receptor (EpoR) complexes. Nonetheless, steady-state erythropoiesis is supported effectively by EpoR alleles that are deficient in cytoplasmic phosphotyrosine sites. To better define core EpoR action mechanisms, signaling capacities of minimal PY-null (EpoR-HM) and PY343-retaining (EpoR-H) alleles were analyzed for the first time in bone marrow-derived erythroblasts. Jak2 activation via each allele was comparable. Stat5 (and several Stat5-response genes) were induced via EpoR-H but not via EpoR-HM. Stat1 and Stat3 activation was nominal for all EpoR forms. For both EpoR-HM and EpoR-H, Akt and p70S6-kinase activation was decreased multifold, and JNK activation was minimal. ERKs, however, were hyperactivated uniquely via EpoR-HM. In vivo, Epo expression in EpoR-HM mice was elevated, while Epo-induced reticulocyte production was diminished. In vitro, EpoR-HM erythroblast maturation also was attenuated (based on DNA content, forward-angle light scatter, and hemoglobinization). These EpoR-HM-specific defects were corrected not only upon PY343 site restoration in EpoR-H, but also upon MEK1,2 inhibition. Core EpoR PY site-independent signals for erythroblast formation therefore appear to be Stat5, Stat1, Stat3, p70S6-kinase, and JNK independent, but ERK dependent. Wild-type signaling capacities, however, depend further upon signals provided via an EpoR/PY343/Stat5 axis.
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Affiliation(s)
- Madhu P Menon
- Program in Stem Cell Biology, Maine Medical Center Research Institute, 81 Research Dr, Scarborough, ME 04074, USA
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45
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Richmond TD, Chohan M, Barber DL. Turning cells red: signal transduction mediated by erythropoietin. Trends Cell Biol 2005; 15:146-55. [PMID: 15752978 DOI: 10.1016/j.tcb.2005.01.007] [Citation(s) in RCA: 267] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Erythropoietin (EPO) is the crucial cytokine regulator of red blood-cell production. Since the discovery of EPO in 1985 and the isolation of its cognate receptor four years later, there has been significant interest in understanding the unique ability of this ligand-receptor pair to promote erythroid mitogenesis, survival and differentiation. The development of knockout mice has elucidated the precise role of the ligand, receptor and downstream players in murine erythroid development. In this review, we summarize EPO-mediated signaling pathways and examine their significance in vivo.
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Affiliation(s)
- Terri D Richmond
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, M5G 2M9, Canada
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Lo RKH, Wise H, Wong YH. Prostacyclin receptor induces STAT1 and STAT3 phosphorylations in human erythroleukemia cells: a mechanism requiring PTX-insensitive G proteins, ERK and JNK. Cell Signal 2005; 18:307-17. [PMID: 15979846 DOI: 10.1016/j.cellsig.2005.05.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Revised: 05/04/2005] [Accepted: 05/04/2005] [Indexed: 12/19/2022]
Abstract
The ability of the human prostacyclin receptor (hIP) to regulate the activities of signal transducers and activators of transcription (STATs) has not yet been documented. In the present study, we have delineated the mechanism by which hIP induces STAT3 phosphorylations in human erythroleukemia (HEL) cells. Stimulation of endogenous hIP by its specific agonist, cicaprost, resulted in STAT3 Tyr705 and Ser727 phosphorylations in a time- and concentration-dependent manner. Cicaprost-induced STAT3 Tyr705 and Ser727 phosphorylations were resistant to pertussis toxin (PTX) treatment, suggesting that these responses were mediated through PTX-insensitive G proteins. In addition, extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), but not p38 MAPK, were shown to be phosphorylated by cicaprost in a time- and concentration-dependent manner via PTX-insensitive G proteins. The levels of the interaction between STAT3, ERK and JNK were enhanced by cicaprost treatment. The involvement of Raf-1, MEK1/2 and JNK in cicaprost-induced phosphorylations of STAT3 was illustrated by the use of their selective inhibitors. In contrast, p38 MAPK did not appear to be required. Similar observations were obtained with STAT1 upon stimulation by cicaprost. Taken together, these results demonstrate for the first time that hIP activation by cicaprost can lead to STAT1 and STAT3 phosphorylations via signaling pathways involving PTX-insensitive G proteins, ERK and JNK.
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Affiliation(s)
- Rico K H Lo
- Department of Biochemistry, Molecular Neuroscience Center, and Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Komyod W, Bauer UM, Heinrich PC, Haan S, Behrmann I. Are STATS arginine-methylated? J Biol Chem 2005; 280:21700-5. [PMID: 15826948 DOI: 10.1074/jbc.c400606200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcription factors of the STAT (signal transducer and activator of transcription) family are important in signal transduction of cytokines. They are subject to post-translational modification by phosphorylation on tyrosine and serine residues. Recent evidence suggested that STATs are methylated on a conserved arginine residue within the N-terminal region. STAT arginine methylation has been described to be important for STAT function and loss of arginine methylation was discussed to be involved in interferon resistance of cancer cells. Here we provide several independent lines of evidence indicating that the issue of arginine methylation of STATs has to be reassessed. First, we show that treatment of melanoma and fibrosarcoma cells with inhibitors used to suppress methylation (N-methyl-2-deoxyadenosine, adenosine, dl-homocysteine) had profound and rapid effects on phosphorylation of STAT1 and STAT3 but also on p38 and Erk signaling cascades which are known to cross-talk with the Jak/STAT pathway. Second, we show that anti-methylarginine antibodies did not precipitate specifically STAT1 or STAT3. Third, we show that mutation of Arg(31) to Lys led to destabilization of STAT1 and STAT3, implicating an important structural role of Arg(31). Finally, purified catalytically active protein arginine methyltransferases (PRMT1, -2, -3, -4, and -6) did not methylate STAT proteins, and cotransfection with PRMT1 did not affect STAT1-controlled reporter gene activity. Taken together, our data suggest the absence of arginine methylation of STAT1 and STAT3.
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Affiliation(s)
- Waraporn Komyod
- Institut für Biochemie, Universitätsklinikum der Rheinisch-Westfälischen Technischen Hochschule Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany
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Mizutani T, Fukushi S, Murakami M, Hirano T, Saijo M, Kurane I, Morikawa S. Tyrosine dephosphorylation of STAT3 in SARS coronavirus-infected Vero E6 cells. FEBS Lett 2005; 577:187-92. [PMID: 15527783 PMCID: PMC7125663 DOI: 10.1016/j.febslet.2004.10.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Revised: 09/27/2004] [Accepted: 10/04/2004] [Indexed: 11/06/2022]
Abstract
Severe acute respiratory syndrome (SARS) has become a global public health emergency. p38 mitogen‐activated protein kinase (MAPK) and its downstream targets are activated in SARS coronavirus (SARS‐CoV)‐infected Vero E6 cells and activation of p38 MAPK enhances the cytopathic effects of SARS‐CoV infection. In addition, weak activation of Akt cannot prevent SARS‐CoV infection‐induced apoptosis in Vero E6 cells. In the present study, we demonstrated that signal transducer and activator of transcription (STAT) 3, which is constitutively phosphorylated at tyrosine (Tyr)‐705 and slightly phosphorylated at serine (Ser)‐727 in Vero E6 cells, was dephosphorylated at Tyr‐705 on SARS‐CoV infection. In addition to phosphorylation of p38 MAPK in virus‐infected cells, other MAPKs, i.e., extracellular signal‐regulated kinase (ERK) 1/2 and c‐Jun N‐terminal kinase (JNK), were phosphorylated. Although inhibitors of ERK1/2 and JNK (PD98059 and SP600125) had no effect on phosphorylation status of STAT3, inhibitors of p38 MAPK (SB203580 and SB202190) partially inhibited dephosphorylation of STAT3 at Tyr‐705. Tyr‐705‐phosphorylated STAT3 was localized mainly in the nucleus in mock infected cells, whereas STAT3 disappeared from the nucleus in virus‐infected cells. As STAT3 acts as an activator of transcription in the nucleus, these results suggest that STAT3 lacks its activity on transcription in SARS‐CoV‐infected Vero E6 cells.
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Affiliation(s)
- Tetsuya Mizutani
- Special Pathogens Laboratory, Department of Virology 1, National Institute of Infectious Diseases, Gakuen 4-7-1, Musashimurayama, Tokyo 208-0011, Japan.
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Sangrar W, Gao Y, Bates B, Zirngibl R, Greer PA. Activated Fps/Fes tyrosine kinase regulates erythroid differentiation and survival. Exp Hematol 2004; 32:935-45. [PMID: 15504549 DOI: 10.1016/j.exphem.2004.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Revised: 06/17/2004] [Accepted: 07/17/2004] [Indexed: 10/26/2022]
Abstract
OBJECTIVE A substantial body of evidence implicates the cytoplasmic protein tyrosine kinase Fps/Fes in regulation of myeloid differentiation and survival. In this study we wished to determine if Fps/Fes also plays a role in the regulation of erythropoiesis. METHODS Mice tissue-specifically expressing a "gain-of-function" mutant fps/fes transgene (fps(MF)) encoding an activated variant of Fps/Fes (MFps), were used to explore the in vivo biological role of Fps/Fes. Erythropoiesis in these mice was assessed by hematological analysis, lineage marker analysis, bone-marrow colony assays, and biochemical approaches. RESULTS fps(MF) mice displayed reductions in peripheral red cell counts. However, there was an accumulation of immature erythroid precursors, which displayed increased survival. Fps/Fes and the related Fer kinase were both detected in early erythroid progenitors/blasts and in mature red cells. Fps/Fes was also activated in response to erythropoietin (EPO) and stem cell factor (SCF), two critical factors in erythroid development. In addition, increased Stat5A/B activation and reduced Erk1/2 phosphorylation was observed in fps(MF) primary erythroid cells in response to EPO or SCF, respectively. CONCLUSIONS These data support a role for Fps/Fes in regulating the survival and differentiation of erythroid cells through modulation of Stat5A/B and Erk kinase pathways induced by EPO and SCF. The increased numbers and survival of erythroid progenitors from fps(MF) mice, and their differential responsiveness to SCF and EPO, implicates Fps/Fes in the commitment of multilineage progenitors to the erythroid lineage. The anemic phenotype in fps(MF) mice suggests that downregulation of Fps/Fes activity might be required for terminal erythroid differentiation.
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Affiliation(s)
- Waheed Sangrar
- Division of Cancer Biology and Genetics, Queen's University Cancer Research Institute, Queen's University, Kingston, Ontario, Canada
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50
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Chen J, Jacobs-Helber SM, Barber DL, Sawyer ST. Erythropoietin-dependent autocrine secretion of tumor necrosis factor-alpha in hematopoietic cells modulates proliferation via MAP kinase–ERK-1/2 and does not require tyrosine docking sites in the EPO receptor. Exp Cell Res 2004; 298:155-66. [PMID: 15242770 DOI: 10.1016/j.yexcr.2004.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2003] [Revised: 04/05/2004] [Indexed: 01/01/2023]
Abstract
Primary erythroid cells and erythroid cell lines may synthesize and secrete tumor necrosis factor-alpha (TNF-alpha) following stimulation with erythropoietin (EPO). The effect of triggering TNF-alpha synthesis and secretion was investigated in erythroleukemia and myeloid cell lines: HCD57, DA3-EPOR, and BAF3-EPOR. The EPO-induced, membrane-bound form of autocrine TNF-alpha seemed to enhance proliferation of HCD57 and DA3-EPOR cells; however, the concentration of secreted autocrine/paracrine TNF-alpha was never sufficient to have an effect. Autocrine TNF-alpha acts through TNFRII receptors to stimulate proliferation. Modulation of mitogen-activated protein kinase (MAPK)/extracellular signal-related kinase (ERK-1/2) activity by the membrane-bound form of autocrine TNF-alpha apparently played a central role in the control of EPO-dependent proliferation of HCD57 and DA3-EPOR cells. Primary erythroid cells and DA3-EPOR cells were found to express similar, high levels of both TNFRI and TNFRII, showing that differential expression of TNF-alpha receptors does not explain why primary cells are inhibited and DA3-EPOR cells are stimulated by autocrine TNF-alpha. BAF3 cells expressing a mutant EPOR with no cytoplasmic tyrosine residues were capable of triggering EPO-dependent TNF-alpha synthesis and secretion, indicating that tyrosine-docking sites in the EPOR were not required for EPO-dependent TNF-alpha secretion.
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MESH Headings
- Animals
- Antigens, CD/drug effects
- Antigens, CD/metabolism
- Autocrine Communication/drug effects
- Autocrine Communication/physiology
- Binding Sites/genetics
- Binding Sites/physiology
- Cell Division/drug effects
- Cell Division/physiology
- Cell Line
- Erythropoietin/pharmacology
- Erythropoietin/physiology
- Hematopoiesis/drug effects
- Hematopoiesis/physiology
- Hematopoietic Stem Cells/drug effects
- Hematopoietic Stem Cells/metabolism
- Mice
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases/metabolism
- Mutation/genetics
- Receptors, Erythropoietin/agonists
- Receptors, Erythropoietin/genetics
- Receptors, Erythropoietin/metabolism
- Receptors, Tumor Necrosis Factor/drug effects
- Receptors, Tumor Necrosis Factor/metabolism
- Receptors, Tumor Necrosis Factor, Type I
- Receptors, Tumor Necrosis Factor, Type II
- Tumor Necrosis Factor-alpha/metabolism
- Tumor Necrosis Factor-alpha/pharmacology
- Tyrosine/metabolism
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Affiliation(s)
- Jingchun Chen
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond 23298, USA
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