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Ayoub MA, Trebaux J, Vallaghe J, Charrier-Savournin F, Al-Hosaini K, Gonzalez Moya A, Pin JP, Pfleger KDG, Trinquet E. Homogeneous time-resolved fluorescence-based assay to monitor extracellular signal-regulated kinase signaling in a high-throughput format. Front Endocrinol (Lausanne) 2014; 5:94. [PMID: 25002860 PMCID: PMC4066300 DOI: 10.3389/fendo.2014.00094] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 06/04/2014] [Indexed: 01/14/2023] Open
Abstract
The extracellular signal-regulated kinases (ERKs) are key components of multiple important cell signaling pathways regulating diverse biological responses. This signaling is characterized by phosphorylation cascades leading to ERK1/2 activation and promoted by various cell surface receptors including G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs). We report the development of a new cell-based Phospho-ERK1/2 assay (designated Phospho-ERK), which is a sandwich proximity-based assay using the homogeneous time-resolved fluorescence technology. We have validated the assay on endogenously expressed ERK1/2 activated by the epidermal growth factor as a prototypical RTK, as well as various GPCRs belonging to different classes and coupling to different heterotrimeric G proteins. The assay was successfully miniaturized in 384-well plates using various cell lines endogenously, transiently, or stably expressing the different receptors. The validation was performed for agonists, antagonists, and inhibitors in dose-response as well as kinetic analysis, and the signaling and pharmacological properties of the different receptors were reproduced. Furthermore, the determination of a Z'-factor value of 0.7 indicates the potential of the Phospho-ERK assay for high-throughput screening of compounds that may modulate ERK1/2 signaling. Finally, our study is of great interest in the current context of investigating ERK1/2 signaling with respect to the emerging concepts of biased ligands, G protein-dependent/independent ERK1/2 activation, and functional transactivation between GPCRs and RTKs, illustrating the importance of considering the ERK1/2 pathway in cell signaling.
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Affiliation(s)
- Mohammed Akli Ayoub
- Molecular Endocrinology and Pharmacology, Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Nedlands, WA, Australia
| | | | | | | | - Khaled Al-Hosaini
- Department of Molecular Pharmacology, CNRS UMR5203, INSERM U661, Institute of Functional Genomics, Universities Montpellier 1 & 2, Montpellier, France
| | | | - Jean-Philippe Pin
- Department of Molecular Pharmacology, CNRS UMR5203, INSERM U661, Institute of Functional Genomics, Universities Montpellier 1 & 2, Montpellier, France
| | - Kevin D. G. Pfleger
- Molecular Endocrinology and Pharmacology, Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Nedlands, WA, Australia
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Ivanova AE, Gorbacheva LR, Strukova SM, Pinelis VG, Reiser G. Activated protein C and thrombin participate in the regulation of astrocyte functions. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2014. [DOI: 10.1134/s1990747813050048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Zhu Z, Reiser G. PAR-1 activation rescues astrocytes through the PI3K/Akt signaling pathway from chemically induced apoptosis that is exacerbated by gene silencing of β-arrestin 1. Neurochem Int 2014; 67:46-56. [DOI: 10.1016/j.neuint.2013.12.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 12/11/2013] [Accepted: 12/18/2013] [Indexed: 12/30/2022]
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Kuhn SA, Martin M, Brodhun M, Kratzsch T, Hanisch UK, Haberl H. Overexpression of protease-activated receptor type 1 (PAR-1) in glioblastoma multiforme WHO IV cells and blood vessels revealed by NCAM-assisted glioblastoma border labeling. Neurol Res 2014; 36:709-21. [PMID: 24620969 DOI: 10.1179/1743132813y.0000000303] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Glioblastomas are neuroepithelial tumors with lost cellular differentiation and tenfold increased growth rates compared to low-grade gliomas. Despite of very aggressive treatment options based on surgery, irradiation, and chemotherapy, the prognosis of affected patients has remained poor and showed only slight improvements during the last 30 years. Research on glioblastoma border zone was hindered by the tumor's intense invasion into the brain parenchyma and the lack of suitable tumor cell markers. Nevertheless, the compact tumor mass and tumor invasion zone are composed of distinct cell types that need to be distinguished from each other to be addressed selectively. As the isoform 140 of the neural cell adhesion molecule (NCAM-140) was recently demonstrated to be lost in human gliomas with rising WHO grade, human multiform glioblastomas were characterized as a NCAM-140 negative entity displaying three main distinct invasion patterns. Evaluation of putative therapy targets within the tumor tissue and tumor invasion zone has been made possible through NCAM-140 negativity. In the present study, brain tissue controls and human glioblastoma samples with compact tumor mass and invasion areas were analyzed for their vascularization at the tumor border and the expression of thrombin receptor protease-activated receptor type 1 (PAR-1) within tumor tissue and vascular vessel walls. Use of NCAM-140 enabled the identification of the tumor invasion zone and its experimental investigation. Tissue vascularization was found to be significantly increased in the compact tumor mass of glioblastomas compared to their invasion zone and tumor-free controls with a significantly high and specific overexpression of PAR-1 within tumor cells and within tumor blood vessels depending upon the tumor area. This suggests thereby a functional role of the thrombin receptor PAR-1 in glioma cell malignancy and glioblastoma neoangiogenesis.
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Marsigliante S, Vetrugno C, Muscella A. CCL20 induces migration and proliferation on breast epithelial cells. J Cell Physiol 2013; 228:1873-83. [PMID: 23460117 DOI: 10.1002/jcp.24349] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 02/08/2013] [Indexed: 12/23/2022]
Abstract
The communication between the tumor cells and the surrounding cells helps drive the process of tumor progression. Since the microenvironment of breast cancer includes CCL20 chemokine, the purpose of this study was to determine whether CCL20 modulates the physiology of healthy breast epithelial cells in areas adjacent to the tumor. Therefore, primary cultures of mammary cells taken from normal peritumoral areas were used. We assessed that breast cells expressed CCR6 CCL20 receptor. Using molecular (siRNA) and pharmacological (inhibitors) techniques, we found multiple signaling kinases to be activated by CCR6 and involved in CCL20-induced breast cell proliferation and migration. The binding of 10 ng/ml CCL20 to CCR6 induced cell migration whilst higher concentrations (from 15 to 25 ng/ml) led to cell proliferation. CCL20 controlled cell migration and MMP-9 expression by PKC-alpha that activated Src, which caused the activation of downstream Akt, JNK, and NF-kB pathways. Furthermore, higher CCL20 concentrations increased cycE and decreased p27Kip expression ending in enhanced cell proliferation. Cell proliferation occurred through PKC-epsilon activation that transactivated EGFR and ERK1/2/MAPK pathway. Although activated by different CCL20 concentrations, these pathways function in parallel and crosstalk to some extent, inasmuch as Akt activation was responsible for ERK1/2 nuclear translocation and enhanced the transcription of of c-fos and c-myc, involved in cell proliferation. In summary, tumor cells exchange signals with the surrounding healthy cells modifying the extracellular matrix through enzyme secretion; thus, CCL20 might be a factor involved in the ontogeny of breast carcinoma.
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Affiliation(s)
- Santo Marsigliante
- Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, Università del Salento, Lecce, Italy
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Nogalski MT, Chan GCT, Stevenson EV, Collins-McMillen DK, Yurochko AD. The HCMV gH/gL/UL128-131 complex triggers the specific cellular activation required for efficient viral internalization into target monocytes. PLoS Pathog 2013; 9:e1003463. [PMID: 23853586 PMCID: PMC3708883 DOI: 10.1371/journal.ppat.1003463] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 05/13/2013] [Indexed: 12/18/2022] Open
Abstract
We have established that HCMV acts as a specific ligand engaging and activating cellular integrins on monocytes. As a result, integrin signaling via Src activation leads to the functional activation of paxillin required for efficient viral entry and for the biological changes in monocytes needed for viral dissemination. These biological/molecular changes allow HCMV to use monocytes as "vehicles" for systemic spread and the establishment of lifelong persistence. However, it remains unresolved how HCMV specifically induces this observed monocyte activation. It was previously demonstrated that the HCMV gH/gL/UL128-131 glycoprotein complex facilitates viral entry into biologically relevant cell types. Nevertheless, the mechanism by which the gH/gL/UL128-131 complex promotes this process is unknown. We now show that only HCMV virions possessing the gH/gL/UL128-131 complex are capable of activating integrin/Src/paxillin-signaling in monocytes. In fibroblasts, this signaling is reversed, such that virus lacking the gH/gL/UL128-131 complex is the only virus able to induce the paxillin activation cascade. The presence of the gH/gL/UL128-131 complex also may have an inhibitory effect on integrin-mediated signaling pathway in fibroblasts. Furthermore, we demonstrate that the presence of the gH/gL/UL128-131 complex on the viral envelope, through its activation of the integrin/Src/paxillin pathway, is necessary for efficient HCMV internalization into monocytes and that appropriate actin and dynamin regulation is critical for this entry process. Importantly, productive infection in monocyte-derived macrophages was seen only in cells exposed to HCMV expressing the gH/gL/UL128-131 complex. From our data, the HCMV gH/gL/U128-131 complex emerges as the specific ligand driving the activation of the receptor-mediated signaling required for the regulation of the actin cytoskeleton and, consequently, for efficient and productive internalization of HCMV into monocytes. To our knowledge, our studies demonstrate a possible molecular mechanism for why the gH/gL/UL128-131 complex dictates HCMV tropism and why the complex is lost as clinical isolates are passaged in the laboratory.
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Affiliation(s)
- Maciej T. Nogalski
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Gary C. T. Chan
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Emily V. Stevenson
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Donna K. Collins-McMillen
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Andrew D. Yurochko
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
- Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
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Yoon H, Radulovic M, Wu J, Blaber SI, Blaber M, Fehlings MG, Scarisbrick IA. Kallikrein 6 signals through PAR1 and PAR2 to promote neuron injury and exacerbate glutamate neurotoxicity. J Neurochem 2013; 127:283-98. [PMID: 23647384 DOI: 10.1111/jnc.12293] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 04/18/2013] [Accepted: 04/29/2013] [Indexed: 01/19/2023]
Abstract
CNS trauma generates a proteolytic imbalance contributing to secondary injury, including axonopathy and neuron degeneration. Kallikrein 6 (Klk6) is a serine protease implicated in neurodegeneration, and here we investigate the role of protease-activated receptors 1 (PAR1) and PAR2 in mediating these effects. First, we demonstrate Klk6 and the prototypical activator of PAR1, thrombin, as well as PAR1 and PAR2, are each elevated in murine experimental traumatic spinal cord injury (SCI) at acute or subacute time points. Recombinant Klk6 triggered extracellular signal-regulated kinase (ERK1/2) signaling in cerebellar granule neurons and in the NSC34 spinal cord motoneuron cell line, in a phosphoinositide 3-kinae and MEK-dependent fashion. Importantly, lipopeptide inhibitors of PAR1 or PAR2, and PAR1 genetic deletion, each reduced Klk6-ERK1/2 activation. In addition, Klk6 and thrombin promoted degeneration of cerebellar neurons and exacerbated glutamate neurotoxicity. Moreover, genetic deletion of PAR1 blocked thrombin-mediated cerebellar neurotoxicity and reduced the neurotoxic effects of Klk6. Klk6 also increased glutamate-mediated Bim signaling, poly-ADP-ribose polymerase cleavage and lactate dehydrogenase release in NSC34 motoneurons and these effects were blocked by PAR1 and PAR2 lipopeptide inhibitors. Taken together, these data point to a novel Klk6-signaling axis in CNS neurons that is mediated by PAR1 and PAR2 and is positioned to contribute to neurodegeneration.
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Affiliation(s)
- Hyesook Yoon
- Neurobiology of Disease Program, Mayo Medical and Graduate School, Rochester, Minnesota, USA; Department of Physical Medicine and Rehabilitation, Mayo Medical and Graduate School, Rochester, Minnesota, USA
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Zhou QB, Duan CZ, Jia Q, Liu P, Li LY. Baicalin attenuates focal cerebral ischemic reperfusion injury by inhibition of protease-activated receptor-1 and apoptosis. Chin J Integr Med 2013; 20:116-22. [DOI: 10.1007/s11655-013-1441-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2012] [Indexed: 12/20/2022]
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STIM1 and Orai1 mediate thrombin-induced Ca2+ influx in rat cortical astrocytes. Cell Calcium 2012; 52:457-67. [DOI: 10.1016/j.ceca.2012.08.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 07/25/2012] [Accepted: 08/08/2012] [Indexed: 12/23/2022]
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Liu Y, Xu L, Zeng Q, Wang J, Wang M, Xi D, Wang X, Yang D, Luo X, Ning Q. Downregulation of FGL2/prothrombinase delays HCCLM6 xenograft tumour growth and decreases tumour angiogenesis. Liver Int 2012; 32:1585-95. [PMID: 22925132 DOI: 10.1111/j.1478-3231.2012.02865.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 07/22/2012] [Indexed: 12/13/2022]
Abstract
BACKGROUND Fibrinogen-like protein 2 (FGL2), which directly generates thrombin from prothrombin without activation of the conventional coagulation cascade, was shown to be overexpressed in various human malignant tumours. AIMS Herein, we aimed to investigate its expression pattern, biological function and mechanism of action in hepatocellular carcinoma (HCC). METHODS FGL2 expression and colocalization with fibrin was examined in 15 HCC tissues. FGL2 downregulation was performed by targeting microRNA in a HCCLM6 cell line in which FGL2 was highly expressed in xenografts of nude mice. The effects of FGL2 knockdown on tumour growth and angiogenesis were evaluated in vitro and in vivo. Cytometric bead arrays were employed to identify FGL2-regulated signalling pathways. RESULTS FGL2 was overexpressed in HCC tissues and colocalized with fibrin deposition. Knockdown of FGL2 expression in HCCLM6 cells (hFGL2(low) HCCLM6) resulted in delayed xenografts tumour growth within an observation period of 42 days and decreased vascularization, which was accompanied by decreased phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). In vitro hFGL2(low) HCCLM6 cells exhibited decreased proliferation without significant induction of apoptosis. Overexpression of FGL2 in HCCLM6 cells or addition of recombinant hFGL2 protein induced phosphorylation of p38-MAPK and ERK1/2 involving protease-activated receptors (PARs).activation. CONCLUSIONS FGL2 contributes to HCC tumour growth and angiogenesis in a thrombin-dependent manner, and downregulation of its expression might be of therapeutic significance in HCC.
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Affiliation(s)
- Yanling Liu
- Department and Institute of Infectious Disease, Tongji hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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61
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Scarisbrick IA, Radulovic M, Burda JE, Larson N, Blaber SI, Giannini C, Blaber M, Vandell AG. Kallikrein 6 is a novel molecular trigger of reactive astrogliosis. Biol Chem 2012; 393:355-67. [PMID: 22505518 DOI: 10.1515/hsz-2011-0241] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 01/20/2012] [Indexed: 01/02/2023]
Abstract
Kallikrein-related peptidase 6 (KLK6) is a trypsin-like serine protease upregulated at sites of central nervous system (CNS) injury, including de novo expression by reactive astrocytes, yet its physiological actions are largely undefined. Taken with recent evidence that KLK6 activates G-protein-coupled protease-activated receptors (PARs), we hypothesized that injury-induced elevations in KLK6 contribute to the development of astrogliosis and that this occurs in a PAR-dependent fashion. Using primary murine astrocytes and the Neu7 astrocyte cell line, we show that KLK6 causes astrocytes to transform from an epitheliod to a stellate morphology and to secrete interleukin 6 (IL-6). By contrast, KLK6 reduced expression of glial fibrillary acidic protein (GFAP). The stellation-promoting activities of KLK6 were shown to be dependent on activation of the thrombin receptor, PAR1, as a PAR1-specific inhibitor, SCH79797, blocked KLK6-induced morphological changes. The ability of KLK6 to promote astrocyte stellation was also shown to be linked to activation of protein kinase C (PKC). These studies indicate that KLK6 is positioned to serve as a molecular trigger of select physiological processes involved in the development of astrogliosis and that this is likely to occur at least in part by activation of the G-protein-coupled receptor, PAR1.
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Affiliation(s)
- Isobel A Scarisbrick
- Neurobiology of Disease Program, Mayo Medical and Graduate School, Rochester, MN 55905, USA.
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Hsieh HL, Lin CC, Chan HJ, Yang CM, Yang CM. c-Src-dependent EGF receptor transactivation contributes to ET-1-induced COX-2 expression in brain microvascular endothelial cells. J Neuroinflammation 2012; 9:152. [PMID: 22747786 PMCID: PMC3410791 DOI: 10.1186/1742-2094-9-152] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 07/02/2012] [Indexed: 02/02/2023] Open
Abstract
Background Endothelin-1 (ET-1) is elevated and participates in the regulation of several brain inflammatory disorders. The deleterious effects of ET-1 on endothelial cells may aggravate brain inflammation mediated through the upregulation of cyclooxygenase-2 (COX-2) gene expression. However, the signaling mechanisms underlying ET-1-induced COX-2 expression in brain microvascular endothelial cells remain unclear. Objective The goal of this study was to examine whether ET-1-induced COX-2 expression and prostaglandin E2 (PGE2) release were mediated through a c-Src-dependent transactivation of epidermal growth factor receptor (EGFR) pathway in brain microvascular endothelial cells (bEnd.3 cells). Methods The expression of COX-2 induced by ET-1 was evaluated by Western blotting and RT-PCR analysis. The COX-2 regulatory signaling pathways were investigated by pretreatment with pharmacological inhibitors, short hairpin RNA (shRNA) or small interfering RNA (siRNA) transfection, chromatin immunoprecipitation (ChIP), and promoter activity reporter assays. Finally, we determined the PGE2 level as a marker of functional activity of COX-2 expression. Results First, the data showed that ET-1-induced COX-2 expression was mediated through a c-Src-dependent transactivation of EGFR/PI3K/Akt cascade. Next, we demonstrated that ET-1 stimulated activation (phosphorylation) of c-Src/EGFR/Akt/MAPKs (ERK1/2, p38 MAPK, and JNK1/2) and then activated the c-Jun/activator protein 1 (AP-1) via Gq/i protein-coupled ETB receptors. The activated c-Jun/AP-1 bound to its corresponding binding sites within COX-2 promoter, thereby turning on COX-2 gene transcription. Ultimately, upregulation of COX-2 by ET-1 promoted PGE2 biosynthesis and release in bEnd.3 cells. Conclusions These results demonstrate that in bEnd.3 cells, c-Src-dependent transactivation of EGFR/PI3K/Akt and MAPKs linking to c-Jun/AP-1 cascade is essential for ET-1-induced COX-2 upregulation. Understanding the mechanisms of COX-2 expression and PGE2 release regulated by ET-1/ETB system on brain microvascular endothelial cells may provide rational therapeutic interventions for brain injury and inflammatory diseases.
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Affiliation(s)
- Hsi-Lung Hsieh
- Department of Nursing, Division of Basic Medical Sciences, Chang Gung University of Science and Technology, Tao-Yuan, Taiwan
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Role of Allergen Source-Derived Proteases in Sensitization via Airway Epithelial Cells. J Allergy (Cairo) 2012; 2012:903659. [PMID: 22523502 PMCID: PMC3303585 DOI: 10.1155/2012/903659] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 09/14/2011] [Accepted: 10/04/2011] [Indexed: 12/12/2022] Open
Abstract
Protease activity is a characteristic common to many allergens. Allergen source-derived proteases interact with lung epithelial cells, which are now thought to play vital roles in both innate and adaptive immune responses. Allergen source-derived proteases act on airway epithelial cells to induce disruption of the tight junctions between epithelial cells, activation of protease-activated receptor-2, and the production of thymic stromal lymphopoietin. These facilitate allergen delivery across epithelial layers and enhance allergenicity or directly activate the immune system through a nonallergic mechanism. Furthermore, they cleave regulatory cell surface molecules involved in allergic reactions. Thus, allergen source-derived proteases are a potentially critical factor in the development of allergic sensitization and appear to be strongly associated with heightened allergenicity.
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McCoy KL, Gyoneva S, Vellano CP, Smrcka AV, Traynelis SF, Hepler JR. Protease-activated receptor 1 (PAR1) coupling to G(q/11) but not to G(i/o) or G(12/13) is mediated by discrete amino acids within the receptor second intracellular loop. Cell Signal 2012; 24:1351-60. [PMID: 22306780 DOI: 10.1016/j.cellsig.2012.01.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Revised: 12/27/2011] [Accepted: 01/19/2012] [Indexed: 12/29/2022]
Abstract
Protease-activated receptor 1 (PAR1) is an unusual GPCR that interacts with multiple G protein subfamilies (G(q/11), G(i/o), and G(12/13)) and their linked signaling pathways to regulate a broad range of pathophysiological processes. However, the molecular mechanisms whereby PAR1 interacts with multiple G proteins are not well understood. Whether PAR1 interacts with various G proteins at the same, different, or overlapping binding sites is not known. Here we investigated the functional and specific binding interactions between PAR1 and representative members of the G(q/11), G(i/o), and G(12/13) subfamilies. We report that G(q/11) physically and functionally interacts with specific amino acids within the second intracellular (i2) loop of PAR1. We identified five amino acids within the PAR1 i2 loop that, when mutated individually, each markedly reduced PAR1 activation of linked inositol phosphate formation in transfected COS-7 cells (functional PAR1-null cells). Among these mutations, only R205A completely abolished direct G(q/11) binding to PAR1 and also PAR1-directed inositol phosphate and calcium mobilization in COS-7 cells and PAR1-/- primary astrocytes. In stark contrast, none of the PAR1 i2 loop mutations disrupted direct PAR1 binding to either G(o) or G(12), or their functional coupling to linked pertussis toxin-sensitive ERK phosphorylation and C3 toxin-sensitive Rho activation, respectively. In astrocytes, our findings suggest that PAR1-directed calcium signaling involves a newly appreciated G(q/11)-PLCε pathway. In summary, we have identified key molecular determinants for PAR1 interactions with G(q/11), and our findings support a model where G(q/11), G(i/o) or G(12/13) each bind to distinct sites within the cytoplasmic regions of PAR1.
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Affiliation(s)
- Kelly L McCoy
- Department of Pharmacology, O. Wayne Rollins Research Center, Emory University School of Medicine, Atlanta, GA 30322, USA
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65
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Sokolova E, Aleshin S, Reiser G. Expression of protease-activated receptor (PAR)-2, but not other PARs, is regulated by inflammatory cytokines in rat astrocytes. Neurochem Int 2012; 60:276-85. [PMID: 22227167 DOI: 10.1016/j.neuint.2011.12.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 11/23/2011] [Accepted: 12/23/2011] [Indexed: 01/09/2023]
Abstract
Protease-activated receptors (PARs) are widely expressed in the central nervous system (CNS) and are believed to play an important role in normal brain functioning as well as in development of various inflammatory and neurodegenerative disorders. Pathological conditions cause altered expression of PARs in brain cells and therefore altered responsiveness to PAR activation. The exact mechanisms of regulation of PAR expression are not well studied. Here, we evaluated in rat astrocytes the influence of LPS, pro-inflammatory cytokines TNFα and IL-1β and continuous PAR activation by PAR agonists on the expression levels of PARs. These stimuli are important in inflammatory and neurological disorders, where their levels are increased. We report that LPS as well as cytokines TNFα and IL-1β affected only the PAR-2 level, but their effects were opposite. LPS and TNFα increased the functional expression of PAR-2, whereas IL-1β down-regulated the functional response of PAR-2. Agonists of PAR-1 specifically increased mRNA level of PAR-2, but not protein level. Transcript levels of other PARs were not changed after PAR-1 activation. Stimulation of the cells with PAR-2 or PAR-4 agonists did not alter PAR levels. We found that up-regulation of PAR-2 is dependent on PKC activity, mostly via its Ca²⁺-sensitive isoforms. Two transcription factors, NFκB and AP-1, are involved in up-regulation of PAR-2. These findings provide new information about the regulation of expression of PAR subtypes in brain cells. This is of importance for targeting PARs, especially PAR-2, for the treatment of CNS disorders.
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Affiliation(s)
- Elena Sokolova
- Otto-von-Guericke-Universität Magdeburg, Medizinische Fakultät, Institut für Neurobiochemie, Leipziger Straße 44, D-39120 Magdeburg, Germany
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Zündorf G, Reiser G. The phosphorylation status of extracellular-regulated kinase 1/2 in astrocytes and neurons from rat hippocampus determines the thrombin-induced calcium release and ROS generation. J Neurochem 2011; 119:1194-204. [PMID: 21988180 DOI: 10.1111/j.1471-4159.2011.07527.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Challenge of protease-activated receptors induces cytosolic Ca(2+) concentration ([Ca(2+) ](c)) increase, mitogen-activated protein kinase activation and reactive oxygen species (ROS) formation with a bandwidth of responses in individual cells. We detected in this study in situ the thrombin-induced [Ca(2+) ](c) rise and ROS formation in dissociated hippocampal astrocytes and neurons in a mixed culture. In identified cells, single cell responses were correlated with extracellular-regulated kinase (ERK)1/2 phosphorylation level. On average, in astrocytes, thrombin induced a transient [Ca(2+) ](c) rise with concentration-dependent increase in amplitude and extrusion rate and high ERK1/2 phosphorylation level. Correlation analysis of [Ca(2+) ](c) response characteristics of single astrocytes reveals that astrocytes with nuclear phosphoERK1/2 localization have a smaller Ca(2+) amplitude and extrusion rate compared with cells with a cytosolic phosphoERK1/2 localization. In naive neurons, without thrombin challenge, variable ERK1/2 phosphorylation patterns are observed. ROS were detected by hydroethidine. Only in neurons with increased ERK1/2 phosphorylation level, we see sustained intracellular rise in fluorescence of the dye lasting over several minutes. ROS formation was abolished by pre-incubation with the NADPH oxidase inhibitor apocynin. Additionally, thrombin induced an immediate, transient hydroethidine fluorescence increase. This was interpreted as NADPH oxidase-mediated O(2) (•-) -release into the extracellular milieu, because it was decreased by pre-incubation with apocynin, and could be eluted by superfusion. In conclusion, the phosphorylation status of ERK1/2 determines the thrombin-dependent [Ca(2+) ](c) increase and ROS formation and, thus, influences the capacity of thrombin to regulate neuroprotection or neurodegeneration.
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Affiliation(s)
- Gregor Zündorf
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
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67
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Shavit E, Michaelson DM, Chapman J. Anatomical localization of protease-activated receptor-1 and protease-mediated neuroglial crosstalk on peri-synaptic astrocytic endfeet. J Neurochem 2011; 119:460-73. [PMID: 21854391 DOI: 10.1111/j.1471-4159.2011.07436.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We studied the localization, activation and function of protease-activated receptor 1 (PAR-1) at the CNS synapse utilizing rat brain synaptosomes and slices. Confocal immunofluoresence and transmission electron microscopy in brain slices with pre-embedding diaminobenzidine (DAB) immunostaining found PAR-1 predominantly localized to the peri-synaptic astrocytic endfeet. Structural confocal immunofluorescence microscopy studies of isolated synaptosomes revealed spherical structures stained with anti-PAR-1 antibody which co-stained mainly for glial-filament acidic protein compared with the neuronal markers synaptophysin and PSD-95. Immunoblot studies of synaptosomes demonstrated an appropriate major band corresponding to PAR-1 and activation of the receptor by a specific agonist peptide (SFLLRN) significantly modulated phosphorylated extracellular signal-regulated kinase. A significant membrane potential depolarization was produced by thrombin (1 U/mL) and the PAR-1 agonist (100 μM) and depolarization by high K(+) elevated extracellular thrombin-like activity in the synaptosomes preparation. The results indicate PAR-1 localized to the peri-synaptic astrocytic endfeet is most likely activated by synaptic proteases and induces cellular signaling and modulation of synaptic electrophysiology. A protease mediated neuron-glia pathway may be important in both physiological and pathological regulation of the synapse.
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Affiliation(s)
- Efrat Shavit
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv, Israel
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68
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Han KS, Mannaioni G, Hamill CE, Lee J, Junge CE, Lee CJ, Traynelis SF. Activation of protease activated receptor 1 increases the excitability of the dentate granule neurons of hippocampus. Mol Brain 2011; 4:32. [PMID: 21827709 PMCID: PMC3170262 DOI: 10.1186/1756-6606-4-32] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 08/10/2011] [Indexed: 11/25/2022] Open
Abstract
Protease activated receptor-1 (PAR1) is expressed in multiple cell types in the CNS, with the most prominent expression in glial cells. PAR1 activation enhances excitatory synaptic transmission secondary to the release of glutamate from astrocytes following activation of astrocytically-expressed PAR1. In addition, PAR1 activation exacerbates neuronal damage in multiple in vivo models of brain injury in a manner that is dependent on NMDA receptors. In the hippocampal formation, PAR1 mRNA appears to be expressed by a subset of neurons, including granule cells in the dentate gyrus. In this study we investigate the role of PAR activation in controlling neuronal excitability of dentate granule cells. We confirm that PAR1 protein is expressed in neurons of the dentate cell body layer as well as in astrocytes throughout the dentate. Activation of PAR1 receptors by the selective peptide agonist TFLLR increased the intracellular Ca2+ concentration in a subset of acutely dissociated dentate neurons as well as non-neuronal cells. Bath application of TFLLR in acute hippocampal slices depolarized the dentate gyrus, including the hilar region in wild type but not in the PAR1-/- mice. PAR1 activation increased the frequency of action potential generation in a subset of dentate granule neurons; cells in which PAR1 activation triggered action potentials showed a significant depolarization. The activation of PAR1 by thrombin increased the amplitude of NMDA receptor-mediated component of EPSPs. These data suggest that activation of PAR1 during normal function or pathological conditions, such as during ischemia or hemorrhage, can increase the excitability of dentate granule cells.
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Affiliation(s)
- Kyung-Seok Han
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA, USA
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69
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Targeting protease-activated receptor-1 with cell-penetrating pepducins in lung cancer. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:513-23. [PMID: 21703428 DOI: 10.1016/j.ajpath.2011.03.025] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 03/10/2011] [Accepted: 03/21/2011] [Indexed: 01/15/2023]
Abstract
Protease-activated receptors (PARs) are G-protein-coupled receptors that are activated by proteolytic cleavage and generation of a tethered ligand. High PAR1 expression has been documented in a variety of invasive cancers of epithelial origin. In the present study, we investigated the contribution of the four PAR family members to motility of lung carcinomas and primary tumor samples from patients. We found that of the four PARs, only PAR1 expression was highly increased in the lung cancer cell lines. Primary lung cancer cells isolated from patient lung tumors migrated at a 10- to 40-fold higher rate than epithelial cells isolated from nonmalignant lung tissue. Cell-penetrating pepducin inhibitors were generated against the first (i1) and third (i3) intracellular loops of PAR1 and tested for their ability to inhibit PAR1-driven migration and extracellular regulated kinase (ERK)1/2 activity. The PAR1 pepducins showed significant inhibition of cell migration in both primary and established cell lines similar to silencing of PAR1 expression with short hairpin RNA (shRNA). Unlike i1 pepducins, the i3 loop pepducins were effective inhibitors of PAR1-mediated ERK activation and tumor growth. Comparable in efficacy with Bevacizumab, monotherapy with the PAR1 i3 loop pepducin P1pal-7 provided significant 75% inhibition of lung tumor growth in nude mice. We identify the PAR1-ERK1/2 pathway as a feasible target for therapy in lung cancer.
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70
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Huang YC, Wu YR, Tseng MY, Chen YC, Hsieh SY, Chen CM. Increased prothrombin, apolipoprotein A-IV, and haptoglobin in the cerebrospinal fluid of patients with Huntington's disease. PLoS One 2011; 6:e15809. [PMID: 21297956 PMCID: PMC3031520 DOI: 10.1371/journal.pone.0015809] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 11/24/2010] [Indexed: 11/19/2022] Open
Abstract
Huntington's disease (HD) is a progressive neurodegenerative disease caused by an unstable CAG trinucleotide repeat expansion. The need for biomarkers of onset and progression in HD is imperative, since currently reliable outcome measures are lacking. We used two-dimensional electrophoresis and mass spectrometry to analyze the proteome profiles in cerebrospinal fluid (CSF) of 6 pairs of HD patients and controls. Prothrombin, apolipoprotein A-IV (Apo A-IV) and haptoglobin were elevated in CSF of the HD patients in comparison with the controls. We used western blot as a semi-quantified measurement for prothrombin and Apo A-IV, as well as enzyme linked immunosorbent assay (ELISA) for measurement of haptoglobin, in 9 HD patients and 9 controls. The albumin quotient (Qalb), a marker of blood-brain barrier (BBB) function, was not different between the HD patients and the controls. The ratios of CSF prothrombin/albumin (prothrombin/Alb) and Apo A-IV/albumin (Apo A-IV/Alb), and haptoglobin level were significantly elevated in HD. The ratio of CSF prothrombin/Alb significantly correlated with the disease severity assessed by Unified Huntington's Disease Rating Scale (UHDRS). The results implicate that increased CSF prothrombin, Apo A-IV, and haptoglobin may be involved in pathogenesis of HD and may serve as potential biomarkers for HD.
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Affiliation(s)
- Yen-Chu Huang
- Department of Neurology, Chang Gung Memorial Hospital, Chang-Gung University College of Medicine, Taipei, Taiwan, People's Republic of China
| | - Yih-Ru Wu
- Department of Neurology, Chang Gung Memorial Hospital, Chang-Gung University College of Medicine, Taipei, Taiwan, People's Republic of China
| | - Mu-Yun Tseng
- Department of Neurology, Chang Gung Memorial Hospital, Chang-Gung University College of Medicine, Taipei, Taiwan, People's Republic of China
| | - Yi-Chun Chen
- Department of Neurology, Chang Gung Memorial Hospital, Chang-Gung University College of Medicine, Taipei, Taiwan, People's Republic of China
| | - Sen-Yung Hsieh
- Clinical Proteomics Center, Chang Gung Memorial Hospital, Taipei, Taiwan, People's Republic of China
| | - Chiung-Mei Chen
- Department of Neurology, Chang Gung Memorial Hospital, Chang-Gung University College of Medicine, Taipei, Taiwan, People's Republic of China
- * E-mail:
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71
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Adams MN, Ramachandran R, Yau MK, Suen JY, Fairlie DP, Hollenberg MD, Hooper JD. Structure, function and pathophysiology of protease activated receptors. Pharmacol Ther 2011; 130:248-82. [PMID: 21277892 DOI: 10.1016/j.pharmthera.2011.01.003] [Citation(s) in RCA: 267] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 01/03/2011] [Indexed: 12/18/2022]
Abstract
Discovered in the 1990s, protease activated receptors(1) (PARs) are membrane-spanning cell surface proteins that belong to the G protein coupled receptor (GPCR) family. A defining feature of these receptors is their irreversible activation by proteases; mainly serine. Proteolytic agonists remove the PAR extracellular amino terminal pro-domain to expose a new amino terminus, or tethered ligand, that binds intramolecularly to induce intracellular signal transduction via a number of molecular pathways that regulate a variety of cellular responses. By these mechanisms PARs function as cell surface sensors of extracellular and cell surface associated proteases, contributing extensively to regulation of homeostasis, as well as to dysfunctional responses required for progression of a number of diseases. This review examines common and distinguishing structural features of PARs, mechanisms of receptor activation, trafficking and signal termination, and discusses the physiological and pathological roles of these receptors and emerging approaches for modulating PAR-mediated signaling in disease.
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Affiliation(s)
- Mark N Adams
- Mater Medical Research Institute, Aubigny Place, Raymond Terrace, South Brisbane Qld 4101, Australia
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72
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Niego B, Samson AL, Petersen KU, Medcalf RL. Thrombin-induced activation of astrocytes in mixed rat hippocampal cultures is inhibited by soluble thrombomodulin. Brain Res 2011; 1381:38-51. [PMID: 21241677 DOI: 10.1016/j.brainres.2011.01.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 11/09/2010] [Accepted: 01/08/2011] [Indexed: 11/19/2022]
Abstract
Thrombin, a serine protease known for its role in coagulation, also induces a variety of protease activated receptor (PAR)-mediated responses in the central nervous system that contribute to many brain pathologies. Since the proteolytic specificity of thrombin is uniquely controlled by thrombomodulin (TM), we investigated the mechanisms by which thrombin and a recombinant soluble form of human TM (Solulin, INN: sothrombomodulin alpha; rhsTM) could influence rat hippocampal cultures. Treatment of hippocampal cultures with thrombin for up to 48h resulted in a significant morphological rearrangement with the formation of expansive cell-free areas (CFAs) and a reduction in cell viability; both effects were blocked by rhsTM. Treatment with the selective PAR-1 agonist, TRAP (SFLLRN) caused the formation of CFAs, suggesting that CFA formation involved PAR-1 signaling. Astrocytes prepared from PAR-1(-/-) mice also had an attenuated CFA response to thrombin. Thrombin-induced CFA formation was a consequence of cell movement and substantial changes in cell morphology, rather than due to cell detachment. Immunocytochemical and functional analyses revealed that the thrombin-sensitive cells within these hippocampal cultures were astrocytes. The effects of thrombin on CFA development were mediated by astrocyte-specific release of intracellular calcium and signalling through ERK1/2. rhsTM was able to attenuate thrombin-induced ERK1/2 phosphorylation. Finally, astrocytes were shown to maintain thrombin-sensitivity following neuronal depletion with NMDA, a result which was confirmed with pure astrocyte cultures. Hence thrombin mediates PAR-1-induced activation of hippocampal astrocytes, but not neurons, in a process that can be modulated by rhsTM.
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Affiliation(s)
- Be'eri Niego
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia
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73
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Kawano Y, Furukawa Y, Kawano Y, Nasu K, Narahara H. Thrombin-induced chemokine production in endometrial stromal cells. Hum Reprod 2010; 26:407-13. [DOI: 10.1093/humrep/deq347] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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74
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Transient receptor potential canonical 3 (TRPC3) mediates thrombin-induced astrocyte activation and upregulates its own expression in cortical astrocytes. J Neurosci 2010; 30:13116-29. [PMID: 20881130 DOI: 10.1523/jneurosci.1890-10.2010] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Reactive astrogliosis, defined by abnormal morphology and excessive cell proliferation, is a characteristic response of astrocytes to CNS injuries, including intracerebral hemorrhage. Thrombin, a major blood-derived serine protease, leaks into the brain parenchyma upon blood-brain barrier disruption and can induce brain injury and astrogliosis. Transient receptor potential canonical (TRPC) channels, Ca(2+)-permeable, nonselective cation channels, are expressed in astrocytes and involved in Ca(2+) influx after receptor stimulation; however, their pathophysiological functions in reactive astrocytes remain unknown. We investigated the pathophysiological roles of TRPC in thrombin-activated cortical astrocytes. Application of thrombin (1 U/ml, 20 h) upregulated TRPC3 protein, which was associated with increased Ca(2+) influx after thapsigargin treatment. Pharmacological manipulations revealed that the TRPC3 upregulation was mediated by protease-activated receptor 1 (PAR-1), extracellular signal-regulated protein kinase, c-Jun NH(2)-terminal kinase, and nuclear factor-κB signaling and required de novo protein synthesis. The Ca(2+) signaling blockers BAPTA-AM, cyclopiazonic acid, and 2-aminoethoxydiphenyl borate and a selective TRPC3 inhibitor, pyrazole-3, attenuated TRPC3 upregulation, suggesting that Ca(2+) signaling through TRPC3 contributes to its increased expression. Thrombin-induced morphological changes at 3 h upregulated S100B, a marker of reactive astrocytes, at 20 h and increased astrocytic proliferation by 72 h, all of which were inhibited by Ca(2+)-signaling blockers and specific knockdown of TRPC3 using small interfering RNA. Intracortical injection of SFLLR-NH(2), a PAR-1 agonist peptide, induced proliferation of astrocytes, most of which were TRPC3 immunopositive. These results suggest that thrombin dynamically upregulates TRPC3 and that TRPC3 contributes to the pathological activation of astrocytes in part through a feedforward upregulation of its own expression.
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75
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Hu H, Yamashita S, Hua Y, Keep RF, Liu W, Xi G. Thrombin-induced neuronal protection: role of the mitogen activated protein kinase/ribosomal protein S6 kinase pathway. Brain Res 2010; 1361:93-101. [PMID: 20846511 DOI: 10.1016/j.brainres.2010.09.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 09/02/2010] [Accepted: 09/03/2010] [Indexed: 10/19/2022]
Abstract
Our previous studies have found that intracerebral pretreatment with a low dose of thrombin (thrombin preconditioning, TPC) reduces infarct volume and attenuates brain edema after focal cerebral ischemia. In this study, we examined whether TPC protects against the neuronal death induced by oxygen glucose deprivation (OGD), and whether the protection is through thrombin receptors and the p44/42 mitogen activated protein kinases (MAPK)/ribosomal protein S6 kinases (p70 S6K) pathway. Expression of protease-activated receptors (PARs) mRNA was detected in cultured primary rat neurons and thrombin upregulated PAR-1 and PAR-4 mRNA expression. TPC reduced OGD-induced neuronal death (e.g. dead cells: 52.5 ± 5.4% vs. 72.3 ± 7.2% in the control group, n=6, p<0.01). Agonists of PAR-1 and PAR-4 mimicked the effects of thrombin and reduced OGD-induced neuronal death. Pretreatment with thrombin or PAR agonists induced the upregulation of activated p44/42 MAPK and p70S6K (Thr 421/Ser 424). PD98059, an inhibitor of p44/42 MAPK kinase, blocked thrombin-induced upregulation of activated p44/42 MAPK and p70S6K. It also reduced TPC-induced neuronal protection (e.g. dead cells: 68.2 ± 5.2% vs. 56.9 ± 4.6% in vehicle+TPC group, n=6, p<0.05). These results suggest that TPC-induced ischemic tolerance is through activation of thrombin receptors and the p44/42 MAPK/p70S6K pathway.
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Affiliation(s)
- Haitao Hu
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA
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76
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Holmström TE, Mattsson CL, Wang Y, Iakovleva I, Petrovic N, Nedergaard J. Non-transactivational, dual pathways for LPA-induced Erk1/2 activation in primary cultures of brown pre-adipocytes. Exp Cell Res 2010; 316:2664-75. [PMID: 20576526 DOI: 10.1016/j.yexcr.2010.05.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 05/21/2010] [Accepted: 05/24/2010] [Indexed: 12/17/2022]
Abstract
In many cell types, G-protein-coupled receptor (GPCR)-induced Erk1/2 MAP kinase activation is mediated via receptor tyrosine kinase (RTK) transactivation, in particular via the epidermal growth factor (EGF) receptor. Lysophosphatidic acid (LPA), acting via GPCRs, is a mitogen and MAP kinase activator in many systems, and LPA can regulate adipocyte proliferation. The mechanism by which LPA activates the Erk1/2 MAP kinase is generally accepted to be via EGF receptor transactivation. In primary cultures of brown pre-adipocytes, EGF can induce Erk1/2 activation, which is obligatory and determinant for EGF-induced proliferation of these cells. Therefore, we have here examined whether LPA, via EGF transactivation, can activate Erk1/2 in brown pre-adipocytes. We found that LPA could induce Erk1/2 activation. However, the LPA-induced Erk1/2 activation was independent of transactivation of EGF receptors (or PDGF receptors) in these cells (whereas in transformed HIB-1B brown adipocytes, the LPA-induced Erk1/2 activation indeed proceeded via EGF receptor transactivation). In the brown pre-adipocytes, LPA instead induced Erk1/2 activation via two distinct non-transactivational pathways, one G(i)-protein dependent, involving PKC and Src activation, the other, a PTX-insensitive pathway, involving PI3K (but not Akt) activation. Earlier studies showing LPA-induced Erk1/2 activation being fully dependent on RTK transactivation have all been performed in cell lines and transfected cells. The present study implies that in non-transformed systems, RTK transactivation may not be involved in the mediation of GPCR-induced Erk1/2 MAP kinase activation.
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Affiliation(s)
- Therese E Holmström
- Department of Physiology, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
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77
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Ohnishi M, Katsuki H, Unemura K, Izumi Y, Kume T, Takada-Takatori Y, Akaike A. Heme oxygenase-1 contributes to pathology associated with thrombin-induced striatal and cortical injury in organotypic slice culture. Brain Res 2010; 1347:170-8. [PMID: 20515663 DOI: 10.1016/j.brainres.2010.05.077] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 05/24/2010] [Accepted: 05/25/2010] [Indexed: 12/14/2022]
Abstract
The blood coagulation factor thrombin that leaks from ruptured vessels initiates brain tissue damage after intracerebral hemorrhage. We have recently shown that mitogen-activated protein kinases (MAPKs) activated by thrombin exacerbate hemorrhagic brain injury via supporting survival of neuropathic microglia. Here, we investigated whether induction of heme oxygenase (HO)-1 is involved in these events. Zinc protoporphyrin IX (ZnPP IX), a HO-1 inhibitor, attenuated thrombin-induced injury of cortical cells in a concentration-dependent manner (0.3-3 microM) and tended to inhibit shrinkage of the striatal tissue at 0.3 microM. HO-1 expression was induced by thrombin in microglia and astrocytes in both the cortex and the striatum. The increase of HO-1 protein was suppressed by a p38 MAPK inhibitor SB203580, and early activation of p38 MAPK after thrombin treatment was observed in neurons and microglia in the striatum. Notably, concomitant application of a low concentration (0.3 microM) of ZnPP IX with thrombin induced apoptotic cell death in striatal microglia and significantly decreased the number of activated microglia in the striatal region. On the other hand, a carbon monoxide releaser reversed the protective effect of ZnPP IX on thrombin-induced injury of cortical cells. Overall, these results suggest that p38 MAPK-dependent induction of HO-1 supports survival of striatal microglia during thrombin insults. Thrombin-induced cortical injury may be also regulated by the expression of HO-1 and the resultant production of heme degradation products such as carbon monoxide.
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Affiliation(s)
- Masatoshi Ohnishi
- Department of Pharmacotherapeutics, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Gakuencho-1, Fukuyama, Hiroshima 729-0292, Japan
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78
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Liu DZ, Ander BP, Xu H, Shen Y, Kaur P, Deng W, Sharp FR. Blood-brain barrier breakdown and repair by Src after thrombin-induced injury. Ann Neurol 2010; 67:526-33. [PMID: 20437588 DOI: 10.1002/ana.21924] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Thrombin mediates the life-threatening cerebral edema that occurs after intracerebral hemorrhage. Therefore, we examined the mechanisms of thrombin-induced injury to the blood-brain barrier (BBB) and subsequent mechanisms of BBB repair. METHODS Intracerebroventricular injection of thrombin (20U) was used to model intraventricular hemorrhage in adult rats. RESULTS Thrombin reduced brain microvascular endothelial cell (BMVEC) and perivascular astrocyte immunoreactivity-indicating either cell injury or death-and functionally disrupted the BBB as measured by increased water content and extravasation of sodium fluorescein and Evans blue dyes 24 hours later. Administration of nonspecific Src family kinase inhibitor (PP2) immediately after thrombin injections blocked brain edema and BBB disruption. At 7 to 14 days after thrombin injections, newborn endothelial cells and astrocytes were observed around cerebral vessels at the time when BBB permeability and cerebral water content resolved. Delayed administration of PP2 on days 2 through 6 after thrombin injections prevented resolution of the edema and abnormal BBB permeability. INTERPRETATION Thrombin, via its protease-activated receptors, is postulated to activate Src kinase phosphorylation of molecules that acutely injure the BBB and produce edema. Thus, acute administration of Src antagonists blocks edema. In contrast, Src blockade for 2 to 6 days after thrombin injections is postulated to prevent resolution of edema and abnormal BBB permeability in part because Src kinase proto-oncogene members stimulate proliferation of newborn BMVECs and perivascular astrocytes in the neurovascular niche that repair the damaged BBB. Thus, Src kinases not only mediate acute BBB injury but also mediate chronic BBB repair after thrombin-induced injury.
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Affiliation(s)
- Da-Zhi Liu
- Department of Neurology, University of California at Davis, Sacramento, CA 95817, USA.
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79
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Isenovic ER, Kedees MH, Haidara MA, Trpkovic A, Mikhailidis DP, Marche P. Involvement of ERK1/2 kinase in insulin-and thrombin-stimulated vascular smooth muscle cell proliferation. Angiology 2010; 61:357-64. [PMID: 20304866 DOI: 10.1177/0003319709358693] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
It is well recognized that the proliferation of vascular smooth muscle cells (VSMCs) is a key event in the pathogenesis of various vascular diseases, including atherosclerosis and hypertension. We have previously shown that among extracellular signal-regulated protein kinases (ERKs), the 42- and 44-kDa isoforms (ERK1/2) participate in the cellular mitogenic machinery triggered by several VSMCs activators, including insulin (INS) and thrombin (Thr). However, understanding of the intracellular signal transduction pathways involved is incomplete. This review considers the recent findings in INS and Thr signaling mechanisms that modulate the proliferation of VSMCs with particular emphasis on the ERK1/2 signaling pathway, an important mediator of VSMCs hypertrophy and vascular disease. Moreover, because the ERK1/2 pathway have been acknowledged as an important mediator of VSMCs hypertrophy, ERK1/2 is identified as a key target for novel therapeutic interventions to minimize irreversible tissue damage associated with hypertension and atherosclerosis.
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Affiliation(s)
- Esma R Isenovic
- Vinca Institute of Nuclear Sciences, University of Belgrade, Laboratory for Molecular Genetics and Radiobiology, Belgrade, Serbia.
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80
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McCoy KL, Traynelis SF, Hepler JR. PAR1 and PAR2 couple to overlapping and distinct sets of G proteins and linked signaling pathways to differentially regulate cell physiology. Mol Pharmacol 2010; 77:1005-15. [PMID: 20215560 DOI: 10.1124/mol.109.062018] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The protease-activated receptors (PAR1 and PAR2) are unusual G protein-coupled receptors that are activated by distinct serine proteases and are coexpressed in many different cell types. Limited recent evidence suggests these closely related receptors regulate different physiological outputs in the same cell, although little is known about the comparative signaling pathways used by these receptors. Here we report that PAR1 and PAR2 couple to overlapping and distinct sets of G proteins to regulate receptor-specific signaling pathways involved in cell migration. In functionally PAR-null COS-7 cells, ectopically expressed PAR1 and PAR2 both form stable complexes with G alpha(q), G alpha(11), G alpha(14), G alpha(12), and G alpha(13). It is surprising that PAR1 but not PAR2 coupled to G alpha(o), G alpha(i1), and G alpha(i2). Consistent with these observations, PAR1 and PAR2 stimulation of inositol phosphate production and RhoA activation was blocked by specific inhibitors of G(q/11) and G(12/13) signaling, respectively. Both receptors stimulated extracellular signal-regulated kinase (ERK) 1/2 phosphorylation, but only PAR1 inhibited adenylyl cyclase activity, and pertussis toxin blocked PAR1 effects on both adenylyl cyclase and ERK1/2 signaling. Neu7 astrocytes express native PAR1 and PAR2 receptors that activate inositol phosphate, RhoA, and ERK1/2 signaling. However, only PAR1 inhibited adenylyl cyclase activity. PAR1 and PAR2 also stimulate Neu7 cell migration. PAR1 effects on ERK1/2 phosphorylation and cell migration were blocked both by pertussis toxin and by the mitogen-activated protein kinase kinase/ERK inhibitor [1,4-diamino-2,3-dicyano-1,4-bis(methylthio)butadiene (U0126)], whereas PAR2 effects were only blocked by U0126. These studies demonstrate that PAR1 and PAR2 physically and functionally link to overlapping and distinct profiles of G proteins to differentially regulate downstream signaling pathways and cell physiology.
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Affiliation(s)
- Kelly L McCoy
- Department of Pharmacology, Rollins Research Center, Emory University School of Medicine, Atlanta, GA 30322, USA
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81
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Gomes MTR, Turchetti AP, Lopes MTP, Salas CE. Stimulation of fibroblast proliferation by the plant cysteine protease CMS2MS2 is independent of its proteolytic activity and requires ERK activation. Biol Chem 2010; 390:1285-91. [PMID: 19747075 DOI: 10.1515/bc.2009.137] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The cysteine protease CMS2MS2 from Carica candamarcensis latex has been shown to enhance proliferation of L929 fibroblast and to activate the extracellular signal-regulated protein kinase (ERK). In experiments with CMS2MS2 irreversibly inhibited by E-64, the proliferative effect on fibroblasts remains unaffected. ERK phosphorylation mediated by CMS2MS2 was abolished in the presence of PD 98059 or U0126, both MAPK cascade inhibitors. In addition, these inhibitors suppress the mitogenic activity of intact CMS2MS2 or CMS2MS2-E-64. Furthermore, ERK phosphorylation and the mitogenic effect are partially suppressed by a phospholipase C (PLC) inhibitor. These data suggest that the mitogenic effect of CMS2MS2 on fibroblasts is independent of its proteolytic activity, requires ERK phosphorylation, and involves activation of PLC.
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Affiliation(s)
- Marco Túlio R Gomes
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, CEP 31270-901, Brazil.
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82
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Wang H, Moreau F, Hirota CL, MacNaughton WK. Proteinase-activated receptors induce interleukin-8 expression by intestinal epithelial cells through ERK/RSK90 activation and histone acetylation. FASEB J 2010; 24:1971-80. [PMID: 20065107 DOI: 10.1096/fj.09-137646] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Proteinase-activated receptors (PARs) are involved in both inflammation and tumorigenesis in epithelial cells. Interleukin (IL)-8 is a potent chemoattractant and is also involved in angiogenesis. The molecular mechanism whereby PARs induce epithelial IL-8 expression is not known. In HT-29 colonic epithelial cells, PAR(1) or PAR(2) agonists stimulated the expression of IL-8 through a NF-kappaB-dependent pathway without inducing IkappaB degradation and disassociation of IkappaB from NF-kappaB. Further studies revealed that PAR activation induced the phosphorylation of p65 at Ser-276 in the nucleus, which increased the recruitment of histone acetyltransferase (HAT) p300 to p50. Inhibition of ERK activation completely blocked PAR-induced IL-8 expression, phosphorylation of p65 and HAT activity. We also demonstrated that RSK p90 was the downstream kinase that mediated ERK-induced nuclear p65 phosphorylation. In conclusion, activation of either PAR(1) or PAR(2) stimulated the transcriptional up-regulation of IL-8 in HT-29 colonic epithelial cells through a pathway that involved ERK/RSK p90, NF-kappaB phosphorylation, and HAT activity. These studies provide evidence of a new role for serine proteinases and PARs in the regulation of gene expression in colonic inflammation and tumorigenesis.
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Affiliation(s)
- Hongying Wang
- Inflammation Research Network, University of Calgary, Calgary, AB, Canada
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83
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Quan L, Jian Z, Ping Z, Weiming L. Proteinase-activated receptor-1 mediates allogeneic CD8(+) T cell-induced apoptosis of vascular endothelial cells. Med Oncol 2009; 26:379-85. [PMID: 19082770 DOI: 10.1007/s12032-008-9132-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Accepted: 11/05/2008] [Indexed: 10/21/2022]
Abstract
Vascular endothelial-cells injury plays a pivotal role in the pathogenesis of graft-versus-host disease (GVHD) and transplant-associated endothelial injury syndrome. Vascular endothelial cells are an exposed target tissue for immune-mediated injury during GVHD. Early endothelial injury syndromes share common features with acute GVHD. Chronic GVHD leads to a rarefaction of microvessels caused by the infiltration of alloreactive cytotoxic T lymphocytes. In this context, allogeneic reactive cytotoxic T cell may contribute to apoptosis of vascular endothelial cells. The involvement of proteinase-activated receptor (PAR-1) in regulation of apoptosis has been recently recognized in many cell types. We hypothesized that apoptosis of vascular endothelial cells induced by allogeneic cytotoxic T cell are mediated via the PAR-1. Allogeneic CD8(+) T cell, PAR-1 agonist peptide (SFLLRN) induced apoptosis of human umbilical vein endothelial cells (HUVECs) and human dermal microvascular endothelial cells (HDMECs) as assessed by AnnexinV-FITC labeling. To ascertain the mechanism of endothelial apoptosis, we determined that allogeneic CD8(+) T cell, SFLLRN enhanced cleavage of caspase-3 and led to p38MAPK activation as assessed by Western blot. The effects of allogeneic CD8(+) T cell and SFLLRN on apoptosis of vascular endothelial cells were largely prevented by a cleavage-blocking anti-human PAR-1-antibody (ATAP2) and a specific inhibitor of p38MAPK. In concert, these observations provide strong evidence that allogeneic CD8(+) T cell induces apoptosis of human vascular endothelial cells through PAR-1-dependent modulation of intrinsic apoptotic pathway via alterations of p38MAPK and caspase-3.
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Affiliation(s)
- Li Quan
- Institute of Hematology, Tong ji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
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84
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Mayer SI, Rössler OG, Endo T, Charnay P, Thiel G. Epidermal-growth-factor-induced proliferation of astrocytes requires Egr transcription factors. J Cell Sci 2009; 122:3340-50. [DOI: 10.1242/jcs.048272] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Stimulation of astrocytes with epidermal growth factor (EGF) induced proliferation and triggered the biosynthesis of the transcription factor Egr-1, involving the activation of the extracellular signal-regulated protein kinase (ERK) signaling pathway. No differences in the proliferation rate of astrocytes prepared from wild-type or Egr-1-deficient mice were detected. However, expression of a dominant-negative mutant of Egr-1 that interfered with DNA-binding of all Egr proteins prevented EGF-induced proliferation of astrocytes. Site-directed mutagenesis of two crucial cysteine residues within the zinc finger DNA-binding domain revealed that DNA-binding of the Egr-1 mutant was essential to inhibit proliferation of EGF-stimulated astrocytes. Expression of NAB2 (a negative co-regulator of Egr-1, Egr-2 and Egr-3) or a dominant-negative mutant of Elk-1 (a key regulator of Egr-1 biosynthesis) abolished EGF-induced proliferation of astrocytes. Chromatin immunoprecipitation experiments showed that Egr-1, Egr-2 and Egr-3 bound to the gene expressing basic fibroblast growth factor (bFGF) in EGF-stimulated astrocytes. Egr-2 and Egr-3 also interacted with the bFGF gene in EGF-stimulated astrocytes prepared from Egr-1-deficient mice, indicating that loss of Egr-1 is compensated by other Egr proteins. Together, these data show that Egr transcription factors are essential for conversion of the mitogenic signal of EGF into a proliferative response.
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Affiliation(s)
- Sabine I. Mayer
- Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical Center, D-66421 Homburg, Germany
| | - Oliver G. Rössler
- Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical Center, D-66421 Homburg, Germany
| | - Takeshi Endo
- Department of Biology, Graduate School of Science, Chiba University, Chiba, Chiba 263-8522, Japan
| | - Patrick Charnay
- INSERM, U784, Ecole Normale Supérieure, 75230 Paris, France
| | - Gerald Thiel
- Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical Center, D-66421 Homburg, Germany
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85
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Kouzaki H, O'Grady SM, Lawrence CB, Kita H. Proteases induce production of thymic stromal lymphopoietin by airway epithelial cells through protease-activated receptor-2. THE JOURNAL OF IMMUNOLOGY 2009; 183:1427-34. [PMID: 19561109 DOI: 10.4049/jimmunol.0900904] [Citation(s) in RCA: 278] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thymic stromal lymphopoietin (TSLP) is produced by epithelial cells and triggers dendritic cell-mediated Th2-type inflammation. Although TSLP is up-regulated in epithelium of patients with asthma, the factors that control TSLP production have not been studied extensively. Because mouse models suggest roles for protease(s) in Th2-type immune responses, we hypothesized that proteases from airborne allergens may induce TSLP production in a human airway epithelial cell line, BEAS-2B. TSLP mRNA and protein were induced when BEAS-2B cells were exposed to prototypic proteases, namely, trypsin and papain. TSLP induction by trypsin required intact protease activity and also a protease-sensing G protein-coupled receptor, protease-activated receptor (PAR)-2; TSLP induction by papain was partially dependent on PAR-2. In humans, exposure to ubiquitous airborne fungi, such as Alternaria, is implicated in the development and exacerbation of asthma. When BEAS-2B cells or normal human bronchial epithelial cells were exposed to Alternaria extract, TSLP was potently induced. The TSLP-inducing activity of Alternaria was partially blocked by treating the extract with a cysteine protease inhibitor, E-64, or by infecting BEAS-2B cells with small interfering RNA for PAR-2. Protease-induced TSLP production by BEAS-2B cells was enhanced synergistically by IL-4 and abolished by IFN-gamma. These findings demonstrate that TSLP expression is induced in airway epithelial cells by exposure to allergen-derived proteases and that PAR-2 is involved in the process. By promoting TSLP production in the airways, proteases associated with airborne allergens may facilitate the development and/or exacerbation of Th2-type airway inflammation, particularly in allergic individuals.
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Affiliation(s)
- Hideaki Kouzaki
- Division of Allergic Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, MN 55905, USA
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86
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Hentschke M, Hentschke S, Borgmeyer U, Hübner CA, Kurth I. The murine AE4 promoter predominantly drives type B intercalated cell specific transcription. Histochem Cell Biol 2009; 132:405-12. [PMID: 19544066 DOI: 10.1007/s00418-009-0614-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2009] [Indexed: 12/11/2022]
Abstract
AE4 is an anion exchanger almost exclusively expressed in the collecting ducts of the kidney. This very restricted expression prompted us to analyze its transcription in more detail. 5' RACE yielded alternative transcriptional start sites that are predicted to code for N-terminal protein variants. Comparison of the 5' genomic sequence between species identified a transcriptionally active region with three conserved spans. In transgenic mice beta-galactosidase expression driven by this fragment resembled endogenous AE4 expression and was predominantly restricted to type B intercalated cells. Hence this promoter could prove useful to target type B intercalated cells by genetic approaches.
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Affiliation(s)
- Moritz Hentschke
- Institute for Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg 20246, Germany
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87
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Rössler OG, Thiel G. Thrombin induces Egr-1 expression in fibroblasts involving elevation of the intracellular Ca2+ concentration, phosphorylation of ERK and activation of ternary complex factor. BMC Mol Biol 2009; 10:40. [PMID: 19432968 PMCID: PMC2686679 DOI: 10.1186/1471-2199-10-40] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 05/11/2009] [Indexed: 01/18/2023] Open
Abstract
Background The serine protease thrombin catalyzes fibrin clot formation by converting fibrinogen into fibrin. Additionally, thrombin stimulation leads to an activation of stimulus-responsive transcription factors in different cell types, indicating that the gene expression pattern is changed in thrombin-stimulated cells. The objective of this study was to analyze the signaling cascade leading to the expression of the zinc finger transcription factor Egr-1 in thrombin-stimulated lung fibroblasts. Results Stimulation of 39M1-81 fibroblasts with thrombin induced a robust and transient biosynthesis of Egr-1. Reporter gene analysis revealed that the newly synthesized Egr-1 was biologically active. The signaling cascade connecting thrombin stimulation with Egr-1 gene expression required elevated levels of cytosolic Ca2+, the activation of diacylgycerol-dependent protein kinase C isoenzymes, and the activation of extracellular signal-regulated protein kinase (ERK). Stimulation of the cells with thrombin triggered the phosphorylation of the transcription factor Elk-1. Expression of a dominant-negative mutant of Elk-1 completely prevented Egr-1 expression in stimulated 39M1-81 cells, indicating that Elk-1 or related ternary complex factors connect the intracellular signaling cascade elicited by activation of protease-activated receptors with transcription of the Egr-1 gene. Lentiviral-mediated expression of MAP kinase phosphatase-1, a dual-specific phosphatase that dephosphorylates and inactivates ERK in the nucleus, prevented Elk-1 phosphorylation and Egr-1 biosynthesis in thrombin stimulated 39M1-81 cells, confirming the importance of nuclear ERK and Elk-1 for the upregulation of Egr-1 expression in thrombin-stimulated lung fibroblasts. 39M1-81 cells additionally express M1 muscarinic acetylcholine receptors. A comparison between the signaling cascades induced by thrombin or carbachol showed no differences, except that signal transduction via M1 muscarinic acetylcholine receptors required the transactivation of the EGF receptor, while thrombin signaling did not. Conclusion This study shows that stimulus-transcription coupling in thrombin-treated lung fibroblasts relies on the elevation of the intracellular Ca2+-concentration and the activation of PKC and ERK. In the nucleus, ternary complex factors function as key proteins linking the intracellular signaling cascade with enhanced transcription of the Egr-1 gene. This study further shows that the dominant-negative Elk-1 mutant is a valuable tool to study Elk-1-mediated gene transcription.
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Affiliation(s)
- Oliver G Rössler
- Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical Center, Homburg, Germany
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88
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Wang D, Paria BC, Zhang Q, Karpurapu M, Li Q, Gerthoffer WT, Nakaoka Y, Rao GN. A role for Gab1/SHP2 in thrombin activation of PAK1: gene transfer of kinase-dead PAK1 inhibits injury-induced restenosis. Circ Res 2009; 104:1066-75. [PMID: 19359598 DOI: 10.1161/circresaha.109.196691] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To understand the role of epidermal growth factor receptor (EGFR) transactivation in G protein-coupled receptor (GPCR) agonist-induced signaling events, we have studied the capacity of thrombin in the activation of Gab1-SHP2 in vascular smooth muscle cells (VSMCs). Thrombin activated both Gab1 and SHP2 in EGFR-dependent manner. Similarly, thrombin induced Rac1 and Cdc42 activation, and these responses were suppressed when either Gab1 or SHP2 stimulation is blocked. Thrombin also induced PAK1 activation in a time- and EGFR-Gab1-SHP2-Rac1/Cdc42-dependent manner. Inhibition of activation of EGFR, Gab1, SHP2, Rac1, Cdc42, or PAK1 by pharmacological or genetic approaches attenuated thrombin-induced VSMC stress fiber formation and motility. Thrombin activated RhoA in a time-dependent manner in VSMCs. LARG, a RhoA-specific GEF (guanine nucleotide exchange factor), was found to be associated with Gab1 and siRNA-mediated depletion of its levels suppressed RhoA, Rac1 and PAK1 activation. Dominant negative mutant-mediated interference of RhoA activation inhibited thrombin-induced Rac1 and PAK1 stimulation in VSMCs and their stress fiber formation and migration. Balloon injury induced PAK1 activity and interference with its activation led to attenuation of SMC migration from media to intima, resulting in reduced neointima formation and increased lumen size. Inhibition of thrombin signaling by recombinant hirudin also blocked balloon injury-induced EGFR tyrosine phosphorylation and PAK1 activity. These results show that thrombin-mediated PAK1 activation plays a crucial role in vascular wall remodeling and it could be a potential target for drug development against these vascular lesions.
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MESH Headings
- Angioplasty, Balloon/adverse effects
- Animals
- Carotid Artery Diseases/enzymology
- Carotid Artery Diseases/etiology
- Carotid Artery Diseases/genetics
- Carotid Artery Diseases/therapy
- Carotid Stenosis/enzymology
- Carotid Stenosis/etiology
- Carotid Stenosis/genetics
- Carotid Stenosis/prevention & control
- Cell Movement
- Cells, Cultured
- Disease Models, Animal
- ErbB Receptors/antagonists & inhibitors
- ErbB Receptors/metabolism
- Fibrinolytic Agents/pharmacology
- Gene Transfer Techniques
- Genetic Therapy/methods
- Guanine Nucleotide Exchange Factors/metabolism
- Hirudins/pharmacology
- Humans
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/pathology
- Mutation
- Phosphoproteins/genetics
- Phosphoproteins/metabolism
- Phosphorylation
- Protein Kinase Inhibitors/pharmacology
- Protein Tyrosine Phosphatase, Non-Receptor Type 11/genetics
- Protein Tyrosine Phosphatase, Non-Receptor Type 11/metabolism
- Quinazolines
- RNA Interference
- RNA, Small Interfering/metabolism
- Rats
- Rho Guanine Nucleotide Exchange Factors
- Stress Fibers/enzymology
- Thrombin/antagonists & inhibitors
- Thrombin/metabolism
- Time Factors
- Transfection
- Tyrphostins/pharmacology
- cdc42 GTP-Binding Protein/metabolism
- p21-Activated Kinases/genetics
- p21-Activated Kinases/metabolism
- rac1 GTP-Binding Protein/metabolism
- rhoA GTP-Binding Protein/metabolism
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Affiliation(s)
- Dong Wang
- Department of Physiology, University of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA
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89
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PKC isoenzymes differentially modulate the effect of thrombin on MAPK-dependent RPE proliferation. Biosci Rep 2009; 28:307-17. [PMID: 18636965 DOI: 10.1042/bsr20080083] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Thrombin signalling through PAR (protease-activated receptor)-1 is involved in cellular processes, such as proliferation, differentiation and cell survival. Following traumatic injury to the eye, thrombin signalling may participate in disorders, such as PVR (proliferative vitreoretinopathy), a human eye disease characterized by the uncontrolled proliferation, transdifferentiation and migration of otherwise quiescent RPE (retinal pigment epithelium) cells. PARs activate the Ras/Raf/MEK/ERK MAPK pathway (where ERK is extracellular-signal-regulated kinase, MAPK is mitogen-activated protein kinase and MEK is MAPK/ERK kinase) through the activation of G(alpha) and G(betagamma) heterotrimeric G-proteins, and the downstream stimulation of the PLC (phospholipase C)-beta/PKC (protein kinase C) and PI3K (phosphoinositide 3-kinase) signalling axis. In the present study, we examined the molecular signalling involved in thrombin-induced RPE cell proliferation, using rat RPE cells in culture as a model system for PVR pathogenesis. Our results showed that thrombin activation of PAR-1 induces RPE cell proliferation through Ras-independent activation of the Raf/MEK/ERK1/2 MAPK signalling cascade. Pharmacological analysis revealed that the activation of 'conventional' PKC isoforms is essential for proliferation, although thrombin-induced phosphorylation of ERK1/2 requires the activation of atypical PKCzeta by PI3K. Consistently, thrombin-induced ERK1/2 activation and RPE cell proliferation were prevented completely by PI3K or PKCzeta inhibition. These results suggest that thrombin induces RPE cell proliferation by joint activation of PLC-dependent and atypical PKC isoforms and the Ras-independent downstream stimulation of the Raf/MEK/ERK1/2 MAPK cascade. The present study is the first report demonstrating directly thrombin-induced ERK phosphorylation in the RPE, and the involvement of atypical PKCzeta in this process.
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90
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Furukawa Y, Kawano Y, Fukuda J, Matsumoto H, Narahara H. The production of vascular endothelial growth factor and metalloproteinase via protease-activated receptor in human endometrial stromal cells. Fertil Steril 2009; 91:535-41. [DOI: 10.1016/j.fertnstert.2007.11.080] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 11/26/2007] [Accepted: 11/26/2007] [Indexed: 10/22/2022]
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91
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Vandell AG, Larson N, Laxmikanthan G, Panos M, Blaber SI, Blaber M, Scarisbrick IA. Protease-activated receptor dependent and independent signaling by kallikreins 1 and 6 in CNS neuron and astroglial cell lines. J Neurochem 2008; 107:855-70. [PMID: 18778305 DOI: 10.1111/j.1471-4159.2008.05658.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
While protease-activated receptors (PARs) are known to mediate signaling events in CNS, contributing both to normal function and pathogenesis, the endogenous activators of CNS PARs are poorly characterized. In this study, we test the hypothesis that kallikreins (KLKs) represent an important pool of endogenous activators of CNS PARs. Specifically, KLK1 and KLK6 were examined for their ability to evoke intracellular Ca(2+) flux in a PAR-dependent fashion in NSC34 neurons and Neu7 astrocytes. Both KLKs were also examined for their ability to activate mitogen-activated protein kinases (extracellular signal-regulated kinases, C-Jun N-terminal kinases, and p38) and protein kinase B (AKT) intracellular signaling cascades. Cumulatively, these studies show that KLK6, but not KLK1, signals through PARs. KLK6 evoked intracellular Ca(2+) flux was mediated by PAR1 in neurons and both PAR1 and PAR2 in astrocytes. Importantly, both KLK1 and KLK6 altered the activation state of mitogen-activated protein kinases and AKT, suggestive of important roles for each in CNS neuron and glial differentiation, and survival. The cellular specificity of CNS-KLK activity was underscored by observations that both proteases promoted AKT activation in astrocytes, but inhibited such signaling in neurons. PAR1 and bradykinin receptor inhibitors were used to demonstrate that KLK1-mediated activation of extracellular signal-regulated kinases in neurons occurred in a non-PAR, bradykinin 2 (B2) receptor-dependent fashion, while similar signaling by KLK6 was mediated by the combined activation of PAR1 and B2. Cumulatively results indicate KLK6, but not KLK1 is an activator of CNS PARs, and that both KLKs are poised to signal in a B2 receptor-dependent fashion to regulate multiple signal transduction pathways relevant to CNS physiologic function and dysfunction.
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Affiliation(s)
- Alexander G Vandell
- Molecular Neuroscience Program, Mayo Medical and Graduate School, Rochester, Minnesota 55905, USA
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92
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Nakao K, Shirakawa H, Sugishita A, Matsutani I, Niidome T, Nakagawa T, Kaneko S. Ca2+mobilization mediated by transient receptor potential canonical 3 is associated with thrombin-induced morphological changes in 1321N1 human astrocytoma cells. J Neurosci Res 2008; 86:2722-32. [DOI: 10.1002/jnr.21711] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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93
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Hsieh HL, Sun CC, Wang TS, Yang CM. PKC-δ/c-Src-mediated EGF receptor transactivation regulates thrombin-induced COX-2 expression and PGE2 production in rat vascular smooth muscle cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1563-75. [DOI: 10.1016/j.bbamcr.2008.03.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 03/12/2008] [Accepted: 03/27/2008] [Indexed: 01/25/2023]
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94
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Sanchez A, Rao HV, Grammas P. PACAP38 protects rat cortical neurons against the neurotoxicity evoked by sodium nitroprusside and thrombin. ACTA ACUST UNITED AC 2008; 152:33-40. [PMID: 18682263 DOI: 10.1016/j.regpep.2008.07.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Revised: 07/02/2008] [Accepted: 07/08/2008] [Indexed: 10/21/2022]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) 38 is a multifunctional anti-inflammatory and anti-apoptotic neuropeptide widely distributed in the nervous system. The objective of this study is to determine whether PACAP38 is neuroprotective against sodium nitroprusside (SNP) and thrombin, two mechanistically distinct neurotoxic agents. Treatment of primary cortical neuronal cultures with 1 mM SNP for 4 h causes neuronal cell death that is significantly reduced by 100 nM PACAP38. PACAP38 down-regulates SNP-induced cell cycle protein (cyclin E) expression and up-regulates p57(KIP2), a cyclin-dependent kinase inhibitor as well as the anti-apoptotic protein Bcl-2. Similarly, neuronal death induced by 100 nM thrombin or the thrombin receptor activating peptide (TRAP 6) is reduced by PACAP38 treatment. Thrombin-stimulated cell cycle protein (cdk4) expression is decreased by PACAP38 while PACAP38 inhibits thrombin-mediated reduction of p57(KIP2). However, the decrease in Bcl-2 evoked by thrombin is not affected by PACAP38. Finally, both SNP and thrombin (or TRAP) increase caspase 3 activity, an effect that is decreased by PACAP38. These data show that PACAP38 supports neuronal survival in vitro suppressing cell cycle progression and enhancing anti-apoptotic proteins. Our results support the possibility that PACAP could be a useful therapeutic agent for reducing neuronal cell death in neurodegenerative diseases.
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Affiliation(s)
- Alma Sanchez
- Department of Neuropsychiatry, Texas Tech University Health Sciences Center, Lubbock TX 79430, USA
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95
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Wang W, Zhang X, Mize GJ, Takayama TK. Protease-activated receptor-1 upregulates fibroblast growth factor 7 in stroma of benign prostatic hyperplasia. Prostate 2008; 68:1064-75. [PMID: 18386288 DOI: 10.1002/pros.20767] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Benign prostatic hyperplasia (BPH) is characterized by abnormal epithelial and stromal proliferation causing urinary obstruction. Prostate growth is regulated by a variety of growth factors secreted from the stroma, including fibroblast growth factor 7 (FGF-7), a potent epithelial-specific growth factor which is increased in hyperplastic prostate. However, the mediator(s) of FGF-7 over-expression is unclear. Protease-activated receptor-1 (PAR-1) is a G-protein coupled receptor known to induce multiple biological processes, but its effect on BPH pathogenesis is mostly unknown. The aim of this study was to investigate the role of PAR-1 as a mediator of BPH development. METHODS PAR-1 expression was investigated in BPH and normal prostate tissues by immunohistochemistry. Prostate stromal cells were isolated from BPH specimens, cultured and immunohistochemically characterized. Cultured stromal cells were stimulated with PAR-1 agonists, and extracellular-signal regulated kinase (ERK1/2) activation and cell proliferation were examined. PAR-1 mediated FGF-7 production by cultured stromal cells was assessed by RT-PCR and immunoassays, and verified by small interfering RNA (siRNA). RESULTS PAR-1 expression was increased in BPH stroma. In stromal cells isolated from BPH tissues, PAR-1 agonists activated ERK1/2 in a time- and concentration-dependent manner and with resultant enhanced cell proliferation. Pertussis toxin-sensitive G protein/(betagamma-subunits)-phosphatidylinositol 3-kinase and protein kinase C pathways were involved in ERK1/2 phosphorylation. PAR-1 activation strikingly induced FGF-7 production from cultured stromal cells mediated predominantly via ERK1/2 signaling pathway, and PAR-1 siRNA decreased the elicited FGF-7 upregulation. CONCLUSIONS The expression and function of PAR-1 in BPH stroma indicate PAR-1 may play important roles in BPH pathogenesis.
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Affiliation(s)
- Wenbin Wang
- Department of Biochemistry, University of Washington, Seattle, Washington 98195-7350, USA
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96
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Herrera AJ, de Pablos RM, Carreño-Müller E, Villarán RF, Venero JL, Tomás-Camardiel M, Cano J, Machado A. The intrastriatal injection of thrombin in rat induced a retrograde apoptotic degeneration of nigral dopaminergic neurons through synaptic elimination. J Neurochem 2008; 105:750-62. [DOI: 10.1111/j.1471-4159.2007.05170.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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97
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Zania P, Papaconstantinou M, Flordellis CS, Maragoudakis ME, Tsopanoglou NE. Thrombin mediates mitogenesis and survival of human endothelial cells through distinct mechanisms. Am J Physiol Cell Physiol 2008; 294:C1215-26. [PMID: 18367587 DOI: 10.1152/ajpcell.00452.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Thrombin has been reported to play a pivotal role in the initiation of angiogenesis by indirectly regulating and organizing a network of angiogenic molecules. In addition, it has been proposed that thrombin can directly activate endothelial cell proliferation. However, in this report it was shown that thrombin is a poor growth factor for human endothelial cells, and its modest mitogenic activity is mediated indirectly by the release of heparin-binding epidermal growth factor, subsequent to proteinase-activated receptor 1 (PAR1) activation. On the other hand, it was demonstrated that thrombin is a potent anti-apoptotic factor for endothelial cells, pointing to a novel role of thrombin in vascular protection. Analysis by annexin V-propidium iodide double staining revealed that thrombin, specifically, promoted survival of serum-starved endothelial cells in a concentration-dependent manner. In contrast to its mitogenic effect, the anti-apoptotic effect of thrombin was largely independent of its catalytic activity and was mediated through interaction with alphanubeta3 and alpha5beta1 integrins, whereas the involvement of PAR1 was limited. These results provide new insights in understanding the role of thrombin in endothelial cell signaling and vascular biology.
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Affiliation(s)
- Panagiota Zania
- Department of Pharmacology, Medical School, University of Patras, 26500 Patras, Greece
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98
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Furuhashi I, Abe K, Sato T, Inoue H. Thrombin-Stimulated Proliferation of Cultured Human Synovial Fibroblasts Through Proteolytic Activation of Proteinase-Activated Receptor-1. J Pharmacol Sci 2008; 108:104-11. [DOI: 10.1254/jphs.08126fp] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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99
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Proteinases and signalling: pathophysiological and therapeutic implications via PARs and more. Br J Pharmacol 2007; 153 Suppl 1:S263-82. [PMID: 18059329 DOI: 10.1038/sj.bjp.0707507] [Citation(s) in RCA: 210] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Proteinases like thrombin, trypsin and tissue kallikreins are now known to regulate cell signaling by cleaving and activating a novel family of G-protein-coupled proteinase-activated receptors (PARs 1-4) via exposure of a tethered receptor-triggering ligand. On their own, short synthetic PAR-selective PAR-activating peptides (PAR-APs) mimicking the tethered ligand sequences can activate PARs 1, 2 and 4 and cause physiological responses both in vitro and in vivo. Using the PAR-APs as sentinel probes in vivo, it has been found that PAR activation can affect the vascular, renal, respiratory, gastrointestinal, musculoskeletal and nervous systems (both central and peripheral nervous system) and can promote cancer metastasis and invasion. In general, responses triggered by PARs 1, 2 and 4 are in keeping with an innate immune inflammatory response, ranging from vasodilatation to intestinal inflammation, increased cytokine production and increased or decreased nociception. Further, PARs have been implicated in a number of disease states, including cancer and inflammation of the cardiovascular, respiratory, musculoskeletal, gastrointestinal and nervous systems. In addition to activating PARs, proteinases can cause hormone-like effects by other signalling mechanisms, like growth factor receptor activation, that may be as important as the activation of PARs. We, therefore, propose that the PARs themselves, their activating serine proteinases and their associated signalling pathways can be considered as attractive targets for therapeutic drug development. Thus, proteinases in general must now be considered as 'hormone-like' messengers that can signal either via PARs or other mechanisms.
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Wang Y, Luo W, Reiser G. Activation of protease-activated receptors in astrocytes evokes a novel neuroprotective pathway through release of chemokines of the growth-regulated oncogene/cytokine-induced neutrophil chemoattractant family. Eur J Neurosci 2007; 26:3159-68. [PMID: 18005059 DOI: 10.1111/j.1460-9568.2007.05938.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Activation of protease-activated receptors (PARs) is known to exert neuroprotection when low concentrations of the agonist protease thrombin are applied. However, the mechanism of protection is still unclear. Here, we showed that activation of multiple PARs, including PAR-1, PAR-2 and PAR-4, was able to elevate the release of the chemokine cytokine-induced neutrophil chemoattractant (CINC)-3 from rat astrocytes, in addition to evoking CINC-1 secretion. Different molecular mechanisms were identified as being involved in the secretion of CINC-1 and CINC-3, upon activation of different PARs. Importantly, we found that both CINC-1 and CINC-3 could signal to rat cortical neurons. Both chemokines acted via CXCR2 to prevent C2-ceramide-induced cytochrome c release from mitochondria. Consequently CINC-1 and CINC-3 protected neurons from apoptosis. We further revealed that conditioned media obtained from PAR-activated astrocytes similarly protected cortical neurons against C2-ceramide-induced cell death. The neuroprotection was considerably suppressed by a CXCR2 antagonist. CXCR2 is the cognate receptor for CINC. Therefore, our findings demonstrate that PAR-activated astrocytes are able to protect neurons against neurodegeneration and cell death via regulation of the secretion of chemokines CINC-1 and CINC-3. These data indicate a previously unknown mechanism for astrocyte-mediated neuroprotection achieved by PAR activation.
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Affiliation(s)
- Yingfei Wang
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany
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