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Babkina I, Savinkova I, Molchanova T, Sidorova M, Surin A, Gorbacheva L. Neuroprotective Effects of Noncanonical PAR1 Agonists on Cultured Neurons in Excitotoxicity. Int J Mol Sci 2024; 25:1221. [PMID: 38279219 PMCID: PMC10816171 DOI: 10.3390/ijms25021221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 01/28/2024] Open
Abstract
Serine proteases regulate cell functions through G protein-coupled protease-activated receptors (PARs). Cleavage of one peptide bond of the receptor amino terminus results in the formation of a new N-terminus ("tethered ligand") that can specifically interact with the second extracellular loop of the PAR receptor and activate it. Activation of PAR1 by thrombin (canonical agonist) and activated protein C (APC, noncanonical agonist) was described as a biased agonism. Here, we have supposed that synthetic peptide analogs to the PAR1 tethered ligand liberated by APC could have neuroprotective effects like APC. To verify this hypothesis, a model of the ischemic brain impairment based on glutamate (Glu) excitotoxicity in primary neuronal cultures of neonatal rats has been used. It was shown that the nanopeptide NPNDKYEPF-NH2 (AP9) effectively reduced the neuronal death induced by Glu. The influence of AP9 on cell survival was comparable to that of APC. Both APC and AP9 reduced the dysregulation of intracellular calcium homeostasis in cultured neurons induced by excitotoxic Glu (100 µM) or NMDA (200 µM) concentrations. PAR1 agonist synthetic peptides might be noncanonical PAR1 agonists and a basis for novel neuroprotective drugs for disorders related to Glu excitotoxicity such as brain ischemia, trauma and some neurodegenerative diseases.
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Affiliation(s)
- Irina Babkina
- Faculty of Medical Biology, Pirogov Russian National Research Medical University of the Ministry of Health of the Russian Federation, 117997 Moscow, Russia; (I.B.); (I.S.)
| | - Irina Savinkova
- Faculty of Medical Biology, Pirogov Russian National Research Medical University of the Ministry of Health of the Russian Federation, 117997 Moscow, Russia; (I.B.); (I.S.)
| | - Tatiana Molchanova
- Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia;
| | - Maria Sidorova
- Chazov National Medical Research Center for Cardiology, Ministry of Health of the Russian Federation, 121552 Moscow, Russia;
| | - Alexander Surin
- Laboratory of Fundamental and Applied Problems of Pain, Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, 119991 Moscow, Russia;
| | - Liubov Gorbacheva
- Faculty of Medical Biology, Pirogov Russian National Research Medical University of the Ministry of Health of the Russian Federation, 117997 Moscow, Russia; (I.B.); (I.S.)
- Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia;
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2
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Scarisbrick IA. PARting Neuroinflammation with Protease-Activated Receptor 2 Pepducins. J Pharmacol Exp Ther 2024; 388:8-11. [PMID: 38169447 DOI: 10.1124/jpet.123.001893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 09/26/2023] [Indexed: 01/05/2024] Open
Affiliation(s)
- Isobel A Scarisbrick
- Center for Regenerative Biotherapeutics, Department of Physical Medicine and Rehabilitation, and Department of Physiology and Biomedical Engineering, Mayo Clinic Graduate School of Biomedical Sciences, Regenerative Sciences, Rochester, Minnesota
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3
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Williams ME, Naudé PJW. The relationship between HIV-1 neuroinflammation, neurocognitive impairment and encephalitis pathology: A systematic review of studies investigating post-mortem brain tissue. Rev Med Virol 2024; 34:e2519. [PMID: 38282400 PMCID: PMC10909494 DOI: 10.1002/rmv.2519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 01/12/2024] [Accepted: 01/17/2024] [Indexed: 01/30/2024]
Abstract
The activities of HIV-1 in the central nervous system (CNS) are responsible for a dysregulated neuroinflammatory response and the subsequent development of HIV-associated neurocognitive disorders (HAND). The use of post-mortem human brain tissue is pivotal for studying the neuroimmune mechanisms of CNS HIV infection. To date, numerous studies have investigated HIV-1-induced neuroinflammation in post-mortem brain tissue. However, from the commonly investigated studies in this line of research, it is not clear which neuroinflammatory markers are consistently associated with HIV neurocognitive impairment (NCI) and neuropathology (i.e., HIV-encephalitis, HIVE). Therefore, we conducted a systematic review of the association between neuroinflammation and NCI/HIVE from studies investigating post-mortem brain tissue. Our aim was to synthesise the published data to date to provide commentary on the most noteworthy markers that are associated with NCI/HIVE. PubMed, Scopus, and Web of Science databases were searched using a search protocol designed specifically for this study. Sixty-one studies were included that investigated the levels of inflammatory markers based on their gene and protein expression in association with NCI/HIVE. The findings revealed that the (1) transcript expressions of IL-1β and TNF-α were consistently associated with NCI/HIVE, whereas CCL2 and IL-6 were commonly not associated with NCI/HIVE, (2) protein expressions of CD14, CD16, CD68, Iba-1, IL-1β and TNF-α were consistently associated with NCI/HIVE, while CD45, GFAP, HLA-DR, IL-1 and IL-6 were commonly not associated with NCI/HIVE, and (3) gene and protein expressions of CNS IL-1β and TNF-α were consistently associated with NCI/HIVE, while IL-6 was consistently not associated with NCI/HIVE. These markers highlight the commonly investigated markers in this line of research and elucidates the neuroinflammatory mechanisms in the HIV-1 brain that are involved in the pathophysiology of NCI/HIVE. These markers and related pathways should be investigated for the development of improved diagnostics, prognostics, and therapeutics of HAND.
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Affiliation(s)
| | - Petrus J. W. Naudé
- Department of Psychiatry and Mental HealthUniversity of Cape TownCape TownSouth Africa
- Neuroscience InstituteUniversity of Cape TownCape TownSouth Africa
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4
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Li B, Li Y, Li S, Li H, Liu L, Xu Y. Inhibition of Protease Activated Receptor 2 Attenuates HBx-Induced Inflammation and Mitochondria Oxidative Stress. Infect Drug Resist 2022; 15:961-973. [PMID: 35299854 PMCID: PMC8921841 DOI: 10.2147/idr.s343864] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 02/19/2022] [Indexed: 01/28/2024] Open
Abstract
BACKGROUND Hepatitis B virus (HBV) infection is one of the global public problems. Among the known infection cases, HBV X protein (HBx) is one of the key inducements of viral replication and host infection. This study was aimed to uncover the role of protease activated receptor 2 (PAR2) on HBx-induced liver injury. METHODS A PAR2-KO mouse model expressing HBx was constructed using hydrodynamics-based in vivo gene transfection method. In addition, pcDNA3.1-HBx was used to over-express HBx in LO2 cells. The effects of HBx overexpression on inflammation and mitochondria oxidative stress were evaluated. RESULTS We found that PAR2 protein level was increased by HBx overexpression. The enforced HBx inhibited LO2 cells apoptosis. Meanwhile, HBx induced inflammation reactions through promoting the secretion of pro-inflammatory cytokines such as TNF-α, IL-6, and CXCL-2. Overexpressed HBx also resulted in mitochondria oxidative stress by upregulation of ROS level and downregulation of MMP and ATP. However, in FSLLRY-NH2 (PAR2 antagonist) treated LO2 cells or PAR2-KO mice, PAR2 blockade reversed the above adverse effects of HBx on liver cells or tissues. CONCLUSION Inhibition of PAR2 may suppress inflammation and mitochondria oxidative stress caused by HBx, pointing out the potential application values of PAR2 antagonist on the treatment of HBV infection in clinic.
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Affiliation(s)
- Bin Li
- Laboratory of Immunology and Pathogenic Biology, Experimental Teaching Center of Basic Medicine, Jinzhou Medical University, Jinzhou City, Liaoning Province, 121001, People’s Republic of China
| | - Yonggang Li
- Department of Pathogenic Biology, School of Basic Medicine, Jinzhou Medical University, Jinzhou City, Liaoning Province, 121001, People’s Republic of China
| | - Shuhua Li
- Laboratory of Immunology and Pathogenic Biology, Experimental Teaching Center of Basic Medicine, Jinzhou Medical University, Jinzhou City, Liaoning Province, 121001, People’s Republic of China
| | - Hongwei Li
- Laboratory of Immunology and Pathogenic Biology, Experimental Teaching Center of Basic Medicine, Jinzhou Medical University, Jinzhou City, Liaoning Province, 121001, People’s Republic of China
| | - Ling Liu
- Laboratory of Immunology and Pathogenic Biology, Experimental Teaching Center of Basic Medicine, Jinzhou Medical University, Jinzhou City, Liaoning Province, 121001, People’s Republic of China
| | - Yao Xu
- School of Pharmacy, Jinzhou Medical University, Jinzhou City, Liaoning Province, 121001, People’s Republic of China
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Liu Y, Li H, Hu J, Wu Z, Meng J, Hayashi Y, Nakanishi H, Qing H, Ni J. Differential Expression and Distinct Roles of Proteinase-Activated Receptor 2 in Microglia and Neurons in Neonatal Mouse Brain After Hypoxia-Ischemic Injury. Mol Neurobiol 2021; 59:717-730. [PMID: 34762231 DOI: 10.1007/s12035-021-02594-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 10/04/2021] [Indexed: 02/05/2023]
Abstract
Regulation of microglial activation and neuroinflammation are critical factors in the pathogenesis of ischemic brain injury. Interest in protease-activated receptor 2 (PAR2) as a pharmaceutical target for various diseases is creasing. However, it is unclear the expression and functions of PAR2 in hypoxia-ischemic (HI) brain injury. Mice with HI and cells with oxygen-glucose deprivation and reoxygenation (OGD/R) were studied. Immunoblot and qRT-PCR were used to study the differential gene expression in cultured microglia and neurons. Immunofluorescent staining was used to study the expression pattern of PAR2 in the HI brain and phagocytotic activity of microglia after OGD/R. In neonatal mice brain after HI, we found PAR2 expression was abundant in neurons, but barely in microglia from the contralateral side of cortex and hippocampus. Conversely, PAR2 expression was barely in neurons while significantly increased in activated microglia from the ipsilateral side of cortex and hippocampus. The activations of PAR2 were increased in both microglia and neuron in a cell model of OGD/R. PAR2 activation mediated the cross-talk between microglia and neurons including the following: microglial PAR2 mediated inflammatory responses that induced neuronal damage; neuronal PAR2 regulated chemokines that recruited activated microglia to damage area; microglia PAR2 controlled the phagocytosis of degenerating neurons. These data suggested differential expression and distinct roles of PAR2 in microglia and neurons after HI injury; thereby, interventions targeting PAR2 may provide insights into the inflammatory-related diseases.
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Affiliation(s)
- Yicong Liu
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.,Stomatology Hospital, School of Stomatology, Clinical Research Center for Oral Diseases of Zhejiang Province, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Zhejiang University School of Medicine, Hangzhou, 310006, China
| | - Hui Li
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Jiangqi Hu
- Department of Prosthodontics, Beijing Stomatological Hospital, School of Stomatology, Capital Medical University, Beijing, 100081, China
| | - Zhou Wu
- Department of Aging Science and Pharmacology, Faculty of Dental Science, Kyushu University, Fukuoka, 812-8582, Japan
| | - Jie Meng
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Yoshinori Hayashi
- Department of Physiology, Nihon University School of Dentistry, Tokyo, 101-8310, Japan
| | - Hiroshi Nakanishi
- Department of Pharmacology, Faculty of Pharmacy, Yasuda Women's University, Hiroshima, 731-0153, Japan
| | - Hong Qing
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
| | - Junjun Ni
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
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6
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Inhibition of PAR-2 Attenuates Neuroinflammation and Improves Short-Term Neurocognitive Functions Via ERK1/2 Signaling Following Asphyxia-Induced Cardiac Arrest in Rats. Shock 2021; 54:539-547. [PMID: 32028357 DOI: 10.1097/shk.0000000000001516] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Global cerebral ischemia-induced neuroinflammation causes neurofunctional impairment following cardiac arrest. Previous studies have demonstrated that the activation of protease-activated receptor-2 (PAR-2) contributes to neuroinflammation. In the present study, we aimed to determine the potential treatment effect of PAR-2 inhibition against neuroinflammation in the setting of asphyxial CA (ACA) in rats. METHODS A total of 116 adult, male Sprague-Dawley rats were randomly divided into Sham (n = 18) and ACA (n = 98) groups. Time course, short-term outcome, and mechanism studies were conducted. All drugs were delivered intranasally. The effect of PAR-2 inhibitor FSLLRY-NH2 on neurocognitive functions was assessed by neurologic deficit score, number of seizures, and T-maze test, while hippocampal neuronal degeneration was evaluated by Fluoro-Jade C staining after ACA. Western blotting was performed for the mechanism study at 24 h following ACA. Selective PAR-2 agonist (AC55541) and ERK1/2 inhibitor (PD98059) were used for intervention. RESULTS Inhibition of PAR-2 decreased neuroinflammation, reduced the number of degenerating hippocampal neurons and improved neurocognitive functions following ACA. PAR-2 activator alone exerted opposite effects to PAR-2 inhibitor. PAR-2 mediated the augmented brain levels of proinflammatory cytokines by promoting the phosphorylation of ERK1/2. CONCLUSIONS PAR-2 inhibition diminished neuroinflammation and thereby reduced hippocampal neuronal degeneration and neurocognitive impairment following ACA. This effect was at least partly mediated via the PAR-2/ERK1/2 signaling.
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7
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Shlobin NA, Har-Even M, Itsekson-Hayosh Z, Harnof S, Pick CG. Role of Thrombin in Central Nervous System Injury and Disease. Biomolecules 2021; 11:562. [PMID: 33921354 PMCID: PMC8070021 DOI: 10.3390/biom11040562] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/04/2021] [Accepted: 04/07/2021] [Indexed: 12/16/2022] Open
Abstract
Thrombin is a Na+-activated allosteric serine protease of the chymotrypsin family involved in coagulation, inflammation, cell protection, and apoptosis. Increasingly, the role of thrombin in the brain has been explored. Low concentrations of thrombin are neuroprotective, while high concentrations exert pathological effects. However, greater attention regarding the involvement of thrombin in normal and pathological processes in the central nervous system is warranted. In this review, we explore the mechanisms of thrombin action, localization, and functions in the central nervous system and describe the involvement of thrombin in stroke and intracerebral hemorrhage, neurodegenerative diseases, epilepsy, traumatic brain injury, and primary central nervous system tumors. We aim to comprehensively characterize the role of thrombin in neurological disease and injury.
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Affiliation(s)
- Nathan A. Shlobin
- Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Meirav Har-Even
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
- Sylvan Adams Sports Institute, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ze’ev Itsekson-Hayosh
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel;
- Department of Neurology and Joseph Sagol Neuroscience Center, The Chaim Sheba Medical Center, Tel HaShomer 5262000, Israel
| | - Sagi Harnof
- Department of Neurosurgery, Beilinson Hospital, Rabin Medical Center, Tel Aviv University, Petah Tikva 4941492, Israel;
| | - Chaim G. Pick
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
- Sylvan Adams Sports Institute, Tel Aviv University, Tel Aviv 6997801, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
- Center for Biology of Addictive Diseases, Tel Aviv University, Tel Aviv 6997801, Israel
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8
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Buhl T, Ikoma A, Kempkes C, Cevikbas F, Sulk M, Buddenkotte J, Akiyama T, Crumrine D, Camerer E, Carstens E, Schön MP, Elias P, Coughlin SR, Steinhoff M. Protease-Activated Receptor-2 Regulates Neuro-Epidermal Communication in Atopic Dermatitis. Front Immunol 2020; 11:1740. [PMID: 32903402 PMCID: PMC7435019 DOI: 10.3389/fimmu.2020.01740] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 06/29/2020] [Indexed: 01/01/2023] Open
Abstract
Background: Activation of protease-activated receptor-2 (PAR2) has been implicated in inflammation, pruritus, and skin barrier regulation, all characteristics of atopic dermatitis (AD), as well as Netherton syndrome which has similar characteristics. However, understanding the precise role of PAR2 on neuro-immune communication in AD has been hampered by the lack of appropriate animal models. Methods: We used a recently established mouse model with epidermal overexpression of PAR2 (PAR2OE) and littermate WT mice to study the impact of increased PAR2 expression in epidermal cells on spontaneous and house dust mite (HDM)-induced skin inflammation, itch, and barrier dysfunction in AD, in vivo and ex vivo. Results: PAR2OE newborns displayed no overt abnormalities, but spontaneously developed dry skin, severe pruritus, and eczema. Dermatological, neurophysiological, and immunological analyses revealed the hallmarks of AD-like skin disease. Skin barrier defects were observed before onset of skin lesions. Application of HDM onto PAR2OE mice triggered pruritus and the skin phenotype. PAR2OE mice displayed an increased density of nerve fibers, increased nerve growth factor and endothelin-1 expression levels, alloknesis, enhanced scratching (hyperknesis), and responses of dorsal root ganglion cells to non-histaminergic pruritogens. Conclusion: PAR2 in keratinocytes, activated by exogenous and endogenous proteases, is sufficient to drive barrier dysfunction, inflammation, and pruritus and sensitize skin to the effects of HDM in a mouse model that mimics human AD. PAR2 signaling in keratinocytes appears to be sufficient to drive several levels of neuro-epidermal communication, another feature of human AD.
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Affiliation(s)
- Timo Buhl
- Department of Dermatology and Surgery, University of California, San Francisco, San Francisco, CA, United States.,Department of Dermatology, Venereology and Allergology, University Medical Center Göttingen, Göttingen, Germany
| | - Akihiko Ikoma
- Department of Dermatology and Surgery, University of California, San Francisco, San Francisco, CA, United States.,Department of Dermatology and UCD Charles Institute for Translational Dermatology, University College Dublin, Dublin, Ireland
| | - Cordula Kempkes
- Department of Dermatology and Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Ferda Cevikbas
- Department of Dermatology and Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Mathias Sulk
- Department of Dermatology and Surgery, University of California, San Francisco, San Francisco, CA, United States.,Department of Dermatology, University Hospital Münster, Münster, Germany
| | - Joerg Buddenkotte
- Department of Dermatology and Venerology, Hamad Medical Corporation, Doha, Qatar.,Translational Research Institute, Academic Health System, Hamad Medical Corporation, Doha, Qatar
| | - Tasuku Akiyama
- Department of Dermatology, Anatomy and Cell Biology, Temple Itch Center, Temple University, Philadelphia, PA, United States.,Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, United States
| | - Debbie Crumrine
- Department of Dermatology and Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Eric Camerer
- INSERM U970, Paris Cardiovascular Research Centre, Paris, France
| | - Earl Carstens
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, United States
| | - Michael P Schön
- Department of Dermatology, Venereology and Allergology, University Medical Center Göttingen, Göttingen, Germany
| | - Peter Elias
- Department of Dermatology and Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Shaun R Coughlin
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
| | - Martin Steinhoff
- Department of Dermatology and Surgery, University of California, San Francisco, San Francisco, CA, United States.,Department of Dermatology and UCD Charles Institute for Translational Dermatology, University College Dublin, Dublin, Ireland.,Department of Dermatology and Venerology, Hamad Medical Corporation, Doha, Qatar.,Translational Research Institute, Academic Health System, Hamad Medical Corporation, Doha, Qatar.,Department of Dermatology, Medical School, University of Qatar, Doha, Qatar.,School of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar.,Department of Dermatology, Weill Cornell Medicine, New York, NY, United States
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9
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Mella C, Figueroa CD, Otth C, Ehrenfeld P. Involvement of Kallikrein-Related Peptidases in Nervous System Disorders. Front Cell Neurosci 2020; 14:166. [PMID: 32655372 PMCID: PMC7324807 DOI: 10.3389/fncel.2020.00166] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 05/18/2020] [Indexed: 12/16/2022] Open
Abstract
Kallikrein-related peptidases (KLKs) are a family of serine proteases that when dysregulated may contribute to neuroinflammation and neurodegeneration. In the present review article, we describe what is known about their physiological and pathological roles with an emphasis on KLK6 and KLK8, two KLKs that are highly expressed in the adult central nervous system (CNS). Altered expression and activity of KLK6 have been linked to brain physiology and the development of multiple sclerosis. On the other hand, altered levels of KLK6 in the brain and serum of people affected by Alzheimer's disease and Parkinson's disease have been documented, pointing out to its function in amyloid metabolism and development of synucleinopathies. People who have structural genetic variants of KLK8 can suffer mental illnesses such as intellectual and learning disabilities, seizures, and autism. Increased expression of KLK8 has also been implicated in schizophrenia, bipolar disorder, and depression. Also, we discuss the possible link that exists between KLKs activity and certain viral infections that can affect the nervous system. Although little is known about the exact mechanisms that mediate KLKs function and their participation in neuroinflammatory and neurodegenerative disorders will open a new field to develop novel therapies to modulate their levels and/or activity and their harmful effects on the CNS.
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Affiliation(s)
- Cinthia Mella
- Faculty of Medicine, Institute of Clinical Microbiology, Universidad Austral de Chile, Valdivia, Chile
- Laboratory of Cellular Pathology, Institute of Anatomy, Histology, and Pathology, Universidad Austral de Chile, Valdivia, Chile
- Center for Interdisciplinary Studies on the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
| | - Carlos D. Figueroa
- Laboratory of Cellular Pathology, Institute of Anatomy, Histology, and Pathology, Universidad Austral de Chile, Valdivia, Chile
- Center for Interdisciplinary Studies on the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
| | - Carola Otth
- Faculty of Medicine, Institute of Clinical Microbiology, Universidad Austral de Chile, Valdivia, Chile
- Center for Interdisciplinary Studies on the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
| | - Pamela Ehrenfeld
- Laboratory of Cellular Pathology, Institute of Anatomy, Histology, and Pathology, Universidad Austral de Chile, Valdivia, Chile
- Center for Interdisciplinary Studies on the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
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10
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Yoon H, Radulovic M, Scarisbrick IA. Kallikrein-related peptidase 6 orchestrates astrocyte form and function through proteinase activated receptor-dependent mechanisms. Biol Chem 2019; 399:1041-1052. [PMID: 29604205 DOI: 10.1515/hsz-2018-0122] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 03/26/2018] [Indexed: 02/01/2023]
Abstract
Kallikrein-related peptidase 6 (Klk6) is the most abundant serine proteinase in the adult central nervous system (CNS), yet we know little regarding its physiological roles or mechanisms of action. Levels of Klk6 in the extracellular environment are dynamically regulated in CNS injury and disease positioning this secreted enzyme to affect cell behavior by potential receptor dependent and independent mechanisms. Here we show that recombinant Klk6 evokes increases in intracellular Ca2+ in primary astrocyte monolayer cultures through activation of proteinase activated receptor 1 (PAR1). In addition, Klk6 promoted a condensation of astrocyte cortical actin leading to an elongated stellate shape and multicellular aggregation in a manner that was dependent on the presence of either PAR1 or PAR2. Klk6-evoked changes in astrocyte shape were accompanied by translocation of β-catenin from the plasma membrane to the cytoplasm. These data are exciting because they demonstrate that Klk6 can influence astrocyte plasticity through receptor-dependent mechanisms. Furthermore, this study expands our understanding of the mechanisms by which kallikreins can contribute to neural homeostasis and remodeling and point to both PAR1 and PAR2 as new therapeutic targets to modulate astrocyte form and function.
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Affiliation(s)
- Hyesook Yoon
- Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN 55905, USA.,Rehabilitation Medicine Research Center, Mayo Clinic, 200 First St., SW, Rochester, MN 55905, USA.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - Maja Radulovic
- Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN 55905, USA.,Rehabilitation Medicine Research Center, Mayo Clinic, 200 First St., SW, Rochester, MN 55905, USA
| | - Isobel A Scarisbrick
- Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN 55905, USA.,Rehabilitation Medicine Research Center, Mayo Clinic, 200 First St., SW, Rochester, MN 55905, USA.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
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11
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Sachan V, Lodge R, Mihara K, Hamelin J, Power C, Gelman BB, Hollenberg MD, Cohen ÉA, Seidah NG. HIV-induced neuroinflammation: impact of PAR1 and PAR2 processing by Furin. Cell Death Differ 2019; 26:1942-1954. [PMID: 30683917 DOI: 10.1038/s41418-018-0264-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 12/12/2018] [Accepted: 12/17/2018] [Indexed: 02/08/2023] Open
Abstract
HIV-associated neurocognitive disorders (HAND) is a syndrome defined by neurocognitive deficits that are driven by viral neurotoxins, cytokines, free radicals, and proteases expressed in the brain. This neurological disease has also been linked to activation of Protease-Activated Receptors 1 and 2 (PAR1,2). These receptors are highly expressed in the central nervous system and are upregulated in HAND. Secretory basic-amino-acid-specific Proprotein Convertases (PCs), which cleave precursor proteins at basic residues, are also induced in HAND. They are vital for many biological processes including HIV-1 entry into cells. The cytoprotective role of Furin, PC5, and PACE4 has been linked to the presence of a potential PC-cleavage site R41XXXXR46↓ in PAR1. Furthermore, Furin binds PAR1 and both are trapped in the trans-Golgi-network (TGN) as inactive proteins, likely due to the intermediary trafficking role of phospho-Furin acidic cluster sorting protein 1 (PACS1). Nothing is known about PAR2 and its possible recognition by PCs at its putative R31XXXXR36↓ processing site. The present study implicates PACS1 in the retrograde trafficking of PAR1 to the TGN and demonstrates that the cytosolic extreme C-terminal tail of PAR1 contains an acidic phosphorylatable PACS1-sensitive domain. We further show the requirement of Asn47 in PAR1 for its Furin-dependent TGN localization. Our data revealed that Furin is the only convertase that efficiently cleaves PAR2 at Arg36↓. N-glycosylation of PAR2 at Asn30 reduces the efficacy, but enhances selectivity of the Furin cleavage. Finally, in co-cultures comprised of human neuroblastoma SK-N-SH cells (stably expressing PAR1/2 and/or Furin) and HIV-1-infected primary macrophages, we demonstrate that the expression of Furin enhances neuronal cell viability in the context of PAR1- or PAR2-induced neuronal cytotoxicity. The present study provides insights into early stages of HIV-1 induced neuronal injury and the protective role of Furin in neurons co-expressing PAR1 and/or PAR2, as observed in HAND.
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Affiliation(s)
- Vatsal Sachan
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (affiliated to the University of Montreal), 110 Pine Ave West, Montreal, QC, H2W1R7, Canada
| | - Robert Lodge
- Laboratory of Human Retrovirology, Montreal Clinical Research Institute (affiliated to the University of Montreal), 110 Pine Ave West, Montreal, QC, H2W1R7, Canada
| | - Koichiro Mihara
- Inflammation Research Network-Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Medicine, Faculty of Medicine, University of Calgary, Calgary, AB, T2N4N1, Canada
| | - Josée Hamelin
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (affiliated to the University of Montreal), 110 Pine Ave West, Montreal, QC, H2W1R7, Canada
| | - Christopher Power
- Department of Medicine, University of Alberta, Edmonton, AB, T6G2S2, Canada
| | - Benjamin B Gelman
- Department of Pathology, University of Texas Medical Branch Houston, Galveston, 77555, TX, USA
| | - Morley D Hollenberg
- Inflammation Research Network-Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Medicine, Faculty of Medicine, University of Calgary, Calgary, AB, T2N4N1, Canada
| | - Éric A Cohen
- Laboratory of Human Retrovirology, Montreal Clinical Research Institute (affiliated to the University of Montreal), 110 Pine Ave West, Montreal, QC, H2W1R7, Canada
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (affiliated to the University of Montreal), 110 Pine Ave West, Montreal, QC, H2W1R7, Canada.
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12
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Yoon H, Radulovic M, Walters G, Paulsen AR, Drucker K, Starski P, Wu J, Fairlie DP, Scarisbrick IA. Protease activated receptor 2 controls myelin development, resiliency and repair. Glia 2017; 65:2070-2086. [PMID: 28921694 DOI: 10.1002/glia.23215] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 08/14/2017] [Accepted: 08/16/2017] [Indexed: 12/22/2022]
Abstract
Oligodendrocytes are essential regulators of axonal energy homeostasis and electrical conduction and emerging target cells for restoration of neurological function. Here we investigate the role of protease activated receptor 2 (PAR2), a unique protease activated G protein-coupled receptor, in myelin development and repair using the spinal cord as a model. Results demonstrate that genetic deletion of PAR2 accelerates myelin production, including higher proteolipid protein (PLP) levels in the spinal cord at birth and higher levels of myelin basic protein and thickened myelin sheaths in adulthood. Enhancements in spinal cord myelin with PAR2 loss-of-function were accompanied by increased numbers of Olig2- and CC1-positive oligodendrocytes, as well as in levels of cyclic adenosine monophosphate (cAMP), and extracellular signal related kinase 1/2 (ERK1/2) signaling. Parallel promyelinating effects were observed after blocking PAR2 expression in purified oligodendrocyte cultures, whereas inhibiting adenylate cyclase reversed these effects. Conversely, PAR2 activation reduced PLP expression and this effect was prevented by brain derived neurotrophic factor (BDNF), a promyelinating growth factor that signals through cAMP. PAR2 knockout mice also showed improved myelin resiliency after traumatic spinal cord injury and an accelerated pattern of myelin regeneration after focal demyelination. These findings suggest that PAR2 is an important controller of myelin production and regeneration, both in the developing and adult spinal cord.
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Affiliation(s)
- Hyesook Yoon
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905.,Department of Physiology and Biomedical Engineering, Rochester, Minnesota, 55905
| | - Maja Radulovic
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905.,Neurobiology of Disease Program, Mayo Clinic, Rochester, Minnesota, 55905
| | - Grant Walters
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905
| | - Alex R Paulsen
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905
| | - Kristen Drucker
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905
| | - Phillip Starski
- Neurobiology of Disease Program, Mayo Clinic, Rochester, Minnesota, 55905
| | - Jianmin Wu
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905
| | - David P Fairlie
- ARC Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Isobel A Scarisbrick
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905.,Department of Physiology and Biomedical Engineering, Rochester, Minnesota, 55905.,Neurobiology of Disease Program, Mayo Clinic, Rochester, Minnesota, 55905
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13
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Lin C, Borensztajn K, Spek CA. Targeting coagulation factor receptors - protease-activated receptors in idiopathic pulmonary fibrosis. J Thromb Haemost 2017; 15:597-607. [PMID: 28079978 DOI: 10.1111/jth.13623] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Indexed: 12/11/2022]
Abstract
Idiopathic pulmonary fibrosis (IPF) is a lethal lung disease with a 5-year mortality rate of > 50% and unknown etiology. Treatment options remain limited and, currently, only two drugs are available, i.e. nintedanib and pirfenidone. However, both of these antifibrotic agents only slow down the progression of the disease, and do not remarkably prolong the survival of IPF patients. Hence, the discovery of new therapeutic targets for IPF is crucial. Studies exploring the mechanisms that are involved in IPF have identified several possible targets for therapeutic interventions. Among these, blood coagulation factor receptors, i.e. protease-activated receptors (PARs), are key candidates, as these receptors mediate the cellular effects of coagulation factors and play central roles in influencing inflammatory and fibrotic responses. In this review, we will focus on the controversial role of the coagulation cascade in the pathogenesis of IPF. In the light of novel data, we will attempt to reconciliate the apparently conflicting data and discuss the possibility of pharmacologic targeting of PARs for the treatment of fibroproliferative diseases.
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Affiliation(s)
- C Lin
- Center for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam, the Netherlands
| | - K Borensztajn
- Center for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam, the Netherlands
- Inserm UMR1152, Medical School Xavier Bichat, Paris, France
- Département Hospitalo-universtaire FIRE (Fibrosis, Inflammation and Remodeling) and LabEx Inflamex, Paris, France
| | - C A Spek
- Center for Experimental and Molecular Medicine, Academic Medical Center, Amsterdam, the Netherlands
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14
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Proteinase-activated receptor 2 is involved in the behavioural changes associated with sickness behaviour. J Neuroimmunol 2016; 295-296:139-47. [DOI: 10.1016/j.jneuroim.2016.04.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 04/25/2016] [Accepted: 04/26/2016] [Indexed: 12/20/2022]
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15
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Yau MK, Lim J, Liu L, Fairlie DP. Protease activated receptor 2 (PAR2) modulators: a patent review (2010-2015). Expert Opin Ther Pat 2016; 26:471-83. [PMID: 26936077 DOI: 10.1517/13543776.2016.1154540] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Protease activated receptor 2 (PAR2) is a self-activated G protein-coupled receptor that has been implicated in several diseases, including inflammatory, gastrointestinal, respiratory, metabolic diseases, cancers and others, making it an important prospective drug target. No known endogenous ligands are available for PAR2, so having potent exogenous agonists and antagonists can be helpful for studying physiological functions of PAR2. AREAS COVERED This review covers agonist-, antagonist-, antibody- and pepducin-based modulators of PAR2 reported in patent applications between 2010-2015, along with their available structure-activity relationships, biological activities and potential uses for studying PAR2. EXPERT OPINION In the last six years, substantial efforts were made towards developing PAR2 modulators, but most lack potency or selectivity or have poor pharmacokinetic profiles. Many PAR2 modulators were assessed by measuring Gαq protein-mediated calcium release in cells. This may be insufficient to fully characterize ligand function, since different ligands signal through PAR2 via multiple signaling pathways. It may be feasible to develop biased ligands as drugs that can selectively modulate one or more specific signaling pathways linking PAR2 to a specific diseased state. Accordingly, potent, orally bioavailable, pathway- and receptor-selective PAR2 modulators may be an achievable goal to realizing effective drugs that can treat PAR2-mediated diseases.
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Affiliation(s)
- Mei-Kwan Yau
- a Division of Chemistry and Structural Biology, Institute for Molecular Bioscience , The University of Queensland , Brisbane , Australia
| | - Junxian Lim
- a Division of Chemistry and Structural Biology, Institute for Molecular Bioscience , The University of Queensland , Brisbane , Australia
| | - Ligong Liu
- a Division of Chemistry and Structural Biology, Institute for Molecular Bioscience , The University of Queensland , Brisbane , Australia
| | - David P Fairlie
- a Division of Chemistry and Structural Biology, Institute for Molecular Bioscience , The University of Queensland , Brisbane , Australia
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The Importance of Thrombin in Cerebral Injury and Disease. Int J Mol Sci 2016; 17:ijms17010084. [PMID: 26761005 PMCID: PMC4730327 DOI: 10.3390/ijms17010084] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 12/28/2015] [Accepted: 12/30/2015] [Indexed: 12/31/2022] Open
Abstract
There is increasing evidence that prothrombin and its active derivative thrombin are expressed locally in the central nervous system. So far, little is known about the physiological and pathophysiological functions exerted by thrombin in the human brain. Extra-hepatic prothrombin expression has been identified in neuronal cells and astrocytes via mRNA measurement. The actual amount of brain derived prothrombin is expected to be 1% or less compared to that in the liver. The role in brain injury depends upon its concentration, as higher amounts cause neuroinflammation and apoptosis, while lower concentrations might even be cytoprotective. Its involvement in numerous diseases like Alzheimer’s, multiple sclerosis, cerebral ischemia and haemorrhage is becoming increasingly clear. This review focuses on elucidation of the cerebral thrombin expression, local generation and its role in injury and disease of the central nervous system.
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Radulovic M, Yoon H, Wu J, Mustafa K, Fehlings MG, Scarisbrick IA. Genetic targeting of protease activated receptor 2 reduces inflammatory astrogliosis and improves recovery of function after spinal cord injury. Neurobiol Dis 2015; 83:75-89. [PMID: 26316358 DOI: 10.1016/j.nbd.2015.08.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 08/01/2015] [Accepted: 08/19/2015] [Indexed: 11/25/2022] Open
Abstract
Inflammatory-astrogliosis exacerbates damage in the injured spinal cord and limits repair. Here we identify Protease Activated Receptor 2 (PAR2) as an essential regulator of these events with mice lacking the PAR2 gene showing greater improvements in motor coordination and strength after compression-spinal cord injury (SCI) compared to wild type littermates. Molecular profiling of the injury epicenter, and spinal segments above and below, demonstrated that mice lacking PAR2 had significantly attenuated elevations in key hallmarks of astrogliosis (glial fibrillary acidic protein (GFAP), vimentin and neurocan) and in expression of pro-inflammatory cytokines (interleukin-6 (IL-6), tumor necrosis factor (TNF) and interleukin-1 beta (IL-1β)). SCI in PAR2-/- mice was also accompanied by improved preservation of protein kinase C gamma (PKCγ)-immunopositive corticospinal axons and reductions in GFAP-immunoreactivity, expression of the pro-apoptotic marker BCL2-interacting mediator of cell death (BIM), and in signal transducer and activator of transcription 3 (STAT3). The potential mechanistic link between PAR2, STAT3 and astrogliosis was further investigated in primary astrocytes to reveal that the SCI-related serine protease, neurosin (kallikrein 6) promotes IL-6 secretion in a PAR2 and STAT3-dependent manner. Data point to a signaling circuit in primary astrocytes in which neurosin signaling at PAR2 promotes IL-6 secretion and canonical STAT3 signaling. IL-6 promotes expression of GFAP, vimentin, additional IL-6 and robust increases in both neurosin and PAR2, thereby driving the PAR2-signaling circuit forward. Given the significant reductions in astrogliosis and inflammation as well as superior neuromotor recovery observed in PAR2 knockout mice after SCI, we suggest that this receptor and its agonists represent new drug targets to foster neuromotor recovery.
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Affiliation(s)
- Maja Radulovic
- Neurobiology of Disease Program, Mayo Medical and Graduate School, Rehabilitation Medicine Research Center, Rochester, MN 55905, United States
| | - Hyesook Yoon
- Department of Physical Medicine and Rehabilitation, Mayo Medical and Graduate School, Rehabilitation Medicine Research Center, Rochester, MN 55905, United States; Department of Physiology and Biomedical Engineering, Mayo Medical and Graduate School, Rehabilitation Medicine Research Center, Rochester, MN 55905, United States
| | - Jianmin Wu
- Department of Physical Medicine and Rehabilitation, Mayo Medical and Graduate School, Rehabilitation Medicine Research Center, Rochester, MN 55905, United States
| | - Karim Mustafa
- Neurobiology of Disease Program, Mayo Medical and Graduate School, Rehabilitation Medicine Research Center, Rochester, MN 55905, United States
| | - Michael G Fehlings
- Department of Surgery, Toronto Western Research Institute, Toronto, ON M5T 2S8, Canada
| | - Isobel A Scarisbrick
- Neurobiology of Disease Program, Mayo Medical and Graduate School, Rehabilitation Medicine Research Center, Rochester, MN 55905, United States; Department of Physical Medicine and Rehabilitation, Mayo Medical and Graduate School, Rehabilitation Medicine Research Center, Rochester, MN 55905, United States; Department of Physiology and Biomedical Engineering, Mayo Medical and Graduate School, Rehabilitation Medicine Research Center, Rochester, MN 55905, United States.
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18
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Hurley MJ, Durrenberger PF, Gentleman SM, Walls AF, Dexter DT. Altered Expression of Brain Proteinase-Activated Receptor-2, Trypsin-2 and Serpin Proteinase Inhibitors in Parkinson's Disease. J Mol Neurosci 2015; 57:48-62. [PMID: 25982926 DOI: 10.1007/s12031-015-0576-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 05/05/2015] [Indexed: 10/23/2022]
Abstract
Neuroinflammation is thought to contribute to cell death in neurodegenerative disorders, but the factors involved in the inflammatory process are not completely understood. Proteinase-activated receptor-2 (PAR2) expression in brain is increased in Alzheimer's disease and multiple sclerosis, but the status of PAR2 in Parkinson's disease is unknown. This study examined expression of PAR2 and endogenous proteinase activators (trypsin-2, mast cell tryptase) and proteinase inhibitors (serpin-A5, serpin-A13) in areas vulnerable and resistant to neurodegeneration in Parkinson's disease at different Braak α-synuclein stages of the disease in post-mortem brain. In normal aged brain, expression of PAR-2, trypsin-2, and serpin-A5 and serpin-A13 was found in neurons and microglia, and alterations in the amount of immunoreactivity for these proteins were found in some brain regions. Namely, there was a decrease in neurons positive for serpin-A5 in the dorsal motor nucleus, and serpin-A13 expression was reduced in the locus coeruleus and primary motor cortex, while expression of PAR2, trypsin-2 and both serpins was reduced in neurons within the substantia nigra. There was an increased number of microglia that expressed serpin-A5 in the dorsal motor nucleus of vagus and elevated numbers of microglia that expressed serpin-A13 in the substantia nigra of late Parkinson's disease cases. The number of microglia that expressed trypsin-2 increased in primary motor cortex of incidental Lewy body disease cases. Analysis of Parkinson's disease cases alone indicated that serpin-A5 and serpin-A13, and trypsin-2 expression in midbrain and cerebral cortex was different in cases with a high incidence of L-DOPA-induced dyskinesia and psychosis compared to those with low levels of these treatment-induced side effects. This study showed that there was altered expression in brain of PAR2 and some proteins that can control its function in Parkinson's disease. Given the role of PAR2 in neuroinflammation, drugs that mitigate these changes may be neuroprotective when administered to patients with Parkinson's disease.
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Affiliation(s)
- Michael J Hurley
- Centre for Neuroinflammation and Neurodegeneration, Division of Brain Sciences, Department of Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK,
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Sitaras N, Rivera JC, Noueihed B, Bien-Aimé M, Zaniolo K, Omri S, Hamel D, Zhu T, Hardy P, Sapieha P, Joyal JS, Chemtob S. Retinal neurons curb inflammation and enhance revascularization in ischemic retinopathies via proteinase-activated receptor-2. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 185:581-95. [PMID: 25478809 DOI: 10.1016/j.ajpath.2014.10.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 09/05/2014] [Accepted: 10/17/2014] [Indexed: 12/22/2022]
Abstract
Ischemic retinopathies are characterized by sequential vaso-obliteration followed by abnormal intravitreal neovascularization predisposing patients to retinal detachment and blindness. Ischemic retinopathies are associated with robust inflammation that leads to generation of IL-1β, which causes vascular degeneration and impairs retinal revascularization in part through the liberation of repulsive guidance cue semaphorin 3A (Sema3A). However, retinal revascularization begins as inflammation culminates in ischemic retinopathies. Because inflammation leads to activation of proteases involved in the formation of vasculature, we hypothesized that proteinase-activated receptor (Par)-2 (official name F2rl1) may modulate deleterious effects of IL-1β. Par2, detected mostly in retinal ganglion cells, was up-regulated in oxygen-induced retinopathy. Surprisingly, oxygen-induced retinopathy-induced vaso-obliteration and neovascularization were unaltered in Par2 knockout mice, suggesting compensatory mechanisms. We therefore conditionally knocked down retinal Par2 with shRNA-Par2-encoded lentivirus. Par2 knockdown interfered with normal revascularization, resulting in pronounced intravitreal neovascularization; conversely, the Par2 agonist peptide (SLIGRL) accelerated normal revascularization. In vitro and in vivo exploration of mechanisms revealed that IL-1β induced Par2 expression, which in turn down-regulated sequentially IL-1 receptor type I and Sema3A expression through Erk/Jnk-dependent processes. Collectively, our findings unveil an important mechanism by which IL-1β regulates its own endothelial cytotoxic actions by augmenting neuronal Par2 expression to repress sequentially IL-1 receptor type I and Sema3A expression. Timely activation of Par2 may be a promising therapeutic avenue in ischemic retinopathies.
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Affiliation(s)
- Nicholas Sitaras
- Department of Pharmacology, CHU Sainte-Justine Hospital, University of Montréal, Montréal, Québec, Canada; Department of Ophthalmology, Maisonneuve-Rosemont Hospital Research Center, University of Montréal, Montréal, Québec, Canada
| | - José Carlos Rivera
- Department of Pharmacology, CHU Sainte-Justine Hospital, University of Montréal, Montréal, Québec, Canada; Department of Ophthalmology, Maisonneuve-Rosemont Hospital Research Center, University of Montréal, Montréal, Québec, Canada.
| | - Baraa Noueihed
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada
| | - Milsa Bien-Aimé
- Department of Ophthalmology, Maisonneuve-Rosemont Hospital Research Center, University of Montréal, Montréal, Québec, Canada
| | - Karine Zaniolo
- LOEX-CUO Research Center, Saint-Sacrement Hospital, Québec, Québec, Canada
| | - Samy Omri
- Department of Pharmacology, CHU Sainte-Justine Hospital, University of Montréal, Montréal, Québec, Canada; Department of Ophthalmology, Maisonneuve-Rosemont Hospital Research Center, University of Montréal, Montréal, Québec, Canada
| | - David Hamel
- Department of Pharmacology, CHU Sainte-Justine Hospital, University of Montréal, Montréal, Québec, Canada
| | - Tang Zhu
- Department of Pharmacology, CHU Sainte-Justine Hospital, University of Montréal, Montréal, Québec, Canada
| | - Pierre Hardy
- Department of Pediatrics, CHU Sainte-Justine Hospital, University of Montréal, Montréal, Québec, Canada
| | - Przemyslaw Sapieha
- Department of Ophthalmology, Maisonneuve-Rosemont Hospital Research Center, University of Montréal, Montréal, Québec, Canada
| | - Jean-Sébastien Joyal
- Department of Pharmacology, CHU Sainte-Justine Hospital, University of Montréal, Montréal, Québec, Canada; Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada; Department of Pediatrics, CHU Sainte-Justine Hospital, University of Montréal, Montréal, Québec, Canada.
| | - Sylvain Chemtob
- Department of Pharmacology, CHU Sainte-Justine Hospital, University of Montréal, Montréal, Québec, Canada; Department of Ophthalmology, Maisonneuve-Rosemont Hospital Research Center, University of Montréal, Montréal, Québec, Canada; Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada; Department of Pediatrics, CHU Sainte-Justine Hospital, University of Montréal, Montréal, Québec, Canada.
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20
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Yau MK, Liu L, Fairlie DP. Toward drugs for protease-activated receptor 2 (PAR2). J Med Chem 2013; 56:7477-97. [PMID: 23895492 DOI: 10.1021/jm400638v] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
PAR2 has a distinctive functional phenotype among an unusual group of GPCRs called protease activated receptors, which self-activate after cleavage of their N-termini by mainly serine proteases. PAR2 is the most highly expressed PAR on certain immune cells, and it is activated by multiple proteases (but not thrombin) in inflammation. PAR2 is expressed on many types of primary human cells and cancer cells. PAR2 knockout mice and PAR2 agonists and antagonists have implicated PAR2 as a promising target in inflammatory conditions; respiratory, gastrointestinal, metabolic, cardiovascular, and neurological dysfunction; and cancers. This article summarizes salient features of PAR2 structure, activation, and function; opportunities for disease intervention via PAR2; pharmacological properties of published or patented PAR2 modulators (small molecule agonists and antagonists, pepducins, antibodies); and some personal perspectives on limitations of assessing their properties and on promising new directions for PAR2 modulation.
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Affiliation(s)
- Mei-Kwan Yau
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland , Brisbane, Queensland 4072, Australia
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21
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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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Brain microbial populations in HIV/AIDS: α-proteobacteria predominate independent of host immune status. PLoS One 2013; 8:e54673. [PMID: 23355888 PMCID: PMC3552853 DOI: 10.1371/journal.pone.0054673] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 12/17/2012] [Indexed: 01/07/2023] Open
Abstract
The brain is assumed to be a sterile organ in the absence of disease although the impact of immune disruption is uncertain in terms of brain microbial diversity or quantity. To investigate microbial diversity and quantity in the brain, the profile of infectious agents was examined in pathologically normal and abnormal brains from persons with HIV/AIDS [HIV] (n = 12), other disease controls [ODC] (n = 14) and in cerebral surgical resections for epilepsy [SURG] (n = 6). Deep sequencing of cerebral white matter-derived RNA from the HIV (n = 4) and ODC (n = 4) patients and SURG (n = 2) groups revealed bacterially-encoded 16 s RNA sequences in all brain specimens with α-proteobacteria representing over 70% of bacterial sequences while the other 30% of bacterial classes varied widely. Bacterial rRNA was detected in white matter glial cells by in situ hybridization and peptidoglycan immunoreactivity was also localized principally in glia in human brains. Analyses of amplified bacterial 16 s rRNA sequences disclosed that Proteobacteria was the principal bacterial phylum in all human brain samples with similar bacterial rRNA quantities in HIV and ODC groups despite increased host neuroimmune responses in the HIV group. Exogenous viruses including bacteriophage and human herpes viruses-4, -5 and -6 were detected variably in autopsied brains from both clinical groups. Brains from SIV- and SHIV-infected macaques displayed a profile of bacterial phyla also dominated by Proteobacteria but bacterial sequences were not detected in experimentally FIV-infected cat or RAG1−/− mouse brains. Intracerebral implantation of human brain homogenates into RAG1−/− mice revealed a preponderance of α-proteobacteria 16 s RNA sequences in the brains of recipient mice at 7 weeks post-implantation, which was abrogated by prior heat-treatment of the brain homogenate. Thus, α-proteobacteria represented the major bacterial component of the primate brain’s microbiome regardless of underlying immune status, which could be transferred into naïve hosts leading to microbial persistence in the brain.
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Maingat FG, Polyak MJ, Paul AM, Vivithanaporn P, Noorbakhsh F, Ahboucha S, Baker GB, Pearson K, Power C. Neurosteroid-mediated regulation of brain innate immunity in HIV/AIDS: DHEA-S suppresses neurovirulence. FASEB J 2012; 27:725-37. [PMID: 23150523 DOI: 10.1096/fj.12-215079] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Neurosteroids are cholesterol-derived molecules synthesized within the brain, which exert trophic and protective actions. Infection by human and feline immunodeficiency viruses (HIV and FIV, respectively) causes neuroinflammation and neurodegeneration, leading to neurological deficits. Secretion of neuroinflammatory host and viral factors by glia and infiltrating leukocytes mediates the principal neuropathogenic mechanisms during lentivirus infections, although the effect of neurosteroids on these processes is unknown. We investigated the interactions between neurosteroid-mediated effects and lentivirus infection outcomes. Analyses of HIV-infected (HIV(+)) and uninfected human brains disclosed a reduction in neurosteroid synthesis enzyme expression. Human neurons exposed to supernatants from HIV(+) macrophages exhibited suppressed enzyme expression without reduced cellular viability. HIV(+) human macrophages treated with sulfated dehydroepiandrosterone (DHEA-S) showed suppression of inflammatory gene (IL-1β, IL-6, TNF-α) expression. FIV-infected (FIV(+)) animals treated daily with 15 mg/kg body weight. DHEA-S treatment reduced inflammatory gene transcripts (IL-1β, TNF-α, CD3ε, GFAP) in brain compared to vehicle-(β-cyclodextrin)-treated FIV(+) animals similar to levels found in vehicle-treated FIV(-) animals. DHEA-S treatment also increased CD4(+) T-cell levels and prevented neurobehavioral deficits and neuronal loss among FIV(+) animals, compared to vehicle-treated FIV(+) animals. Reduced neuronal neurosteroid synthesis was evident in lentivirus infections, but treatment with DHEA-S limited neuroinflammation and prevented neurobehavioral deficits. Neurosteroid-derived therapies could be effective in the treatment of virus- or inflammation-mediated neurodegeneration.
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Neuroprotective effect of protease-activated receptor-2 in the hypoxia-induced apoptosis of rat RGC-5 cells. J Mol Neurosci 2012; 50:98-108. [PMID: 22949040 DOI: 10.1007/s12031-012-9876-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 08/10/2012] [Indexed: 12/11/2022]
Abstract
Hypoxia-induced apoptosis of retinal ganglion cells (RGCs) is regarded as a pivotal pathological process in various ocular diseases. Protease-activated receptor-2 (PAR-2) is involved in the regulation of cell inflammation, differentiation, and apoptosis in many cell types and tissues, but the role of PAR-2 in RGCs under pathological conditions remains unknown. The purpose of this study was to investigate the role of PAR-2 in the apoptosis of RGCs under hypoxic stress. An immortalized rat RGC line (RGC-5) was exposed to hypoxia (5 % O₂). The expression and location of PAR-2 in RGC-5 cells under hypoxia stress were investigated using real-time PCR, western blotting and immunocytochemistry. Cell viability was determined using the Cell Counting Kit-8 assay. Apoptosis was detected using Hoechst 33342 staining and AnnexinV-FITC/PI assays. The role of Bcl-2, Bax, and the active subunit of caspase-3 was also investigated. The results showed that PAR-2 was functionally expressed in RGC-5 cells and up-regulated at both mRNA and protein levels under hypoxic stress. The PAR-2 selective agonist, SLIGRL, rescued RGC-5 cells from hypoxia-induced apoptosis through up-regulation of the Bcl-2/Bax ratio and down-regulation of caspase-3 activation. This study provides the first evidence that PAR-2 has a protective effect against the hypoxia-induced apoptosis of RGC-5 cells.
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Caliendo G, Santagada V, Perissutti E, Severino B, Fiorino F, Frecentese F, Juliano L. Kallikrein protease activated receptor (PAR) axis: an attractive target for drug development. J Med Chem 2012; 55:6669-86. [PMID: 22607152 DOI: 10.1021/jm300407t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Giuseppe Caliendo
- Dipartimento di Chimica Farmaceutica e Tossicologica, Università degli Studi di Napoli Federico II, Via D. Montesano, 49, 80131, Napoli, Italy.
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Targeting proteinase-activated receptors: therapeutic potential and challenges. Nat Rev Drug Discov 2012; 11:69-86. [PMID: 22212680 DOI: 10.1038/nrd3615] [Citation(s) in RCA: 240] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Proteinase-activated receptors (PARs), a family of four seven-transmembrane G protein-coupled receptors, act as targets for signalling by various proteolytic enzymes. PARs are characterized by a unique activation mechanism involving the proteolytic unmasking of a tethered ligand that stimulates the receptor. Given the emerging roles of these receptors in cancer as well as in disorders of the cardiovascular, musculoskeletal, gastrointestinal, respiratory and central nervous system, PARs have become attractive targets for the development of novel therapeutics. In this Review we summarize the mechanisms by which PARs modulate cell function and the roles they can have in physiology and diseases. Furthermore, we provide an overview of possible strategies for developing PAR antagonists.
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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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Noorbakhsh F, Ellestad KK, Maingat F, Warren KG, Han MH, Steinman L, Baker GB, Power C. Impaired neurosteroid synthesis in multiple sclerosis. ACTA ACUST UNITED AC 2011; 134:2703-21. [PMID: 21908875 DOI: 10.1093/brain/awr200] [Citation(s) in RCA: 163] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
High-throughput technologies have led to advances in the recognition of disease pathways and their underlying mechanisms. To investigate the impact of micro-RNAs on the disease process in multiple sclerosis, a prototypic inflammatory neurological disorder, we examined cerebral white matter from patients with or without the disease by micro-RNA profiling, together with confirmatory reverse transcription-polymerase chain reaction analysis, immunoblotting and gas chromatography-mass spectrometry. These observations were verified using the in vivo multiple sclerosis model, experimental autoimmune encephalomyelitis. Brains of patients with or without multiple sclerosis demonstrated differential expression of multiple micro-RNAs, but expression of three neurosteroid synthesis enzyme-specific micro-RNAs (miR-338, miR-155 and miR-491) showed a bias towards induction in patients with multiple sclerosis (P < 0.05). Analysis of the neurosteroidogenic pathways targeted by micro-RNAs revealed suppression of enzyme transcript and protein levels in the white matter of patients with multiple sclerosis (P < 0.05). This was confirmed by firefly/Renilla luciferase micro-RNA target knockdown experiments (P < 0.05) and detection of specific micro-RNAs by in situ hybridization in the brains of patients with or without multiple sclerosis. Levels of important neurosteroids, including allopregnanolone, were suppressed in the white matter of patients with multiple sclerosis (P < 0.05). Induction of the murine micro-RNAs, miR-338 and miR-155, accompanied by diminished expression of neurosteroidogenic enzymes and allopregnanolone, was also observed in the brains of mice with experimental autoimmune encephalomyelitis (P < 0.05). Allopregnanolone treatment of the experimental autoimmune encephalomyelitis mouse model limited the associated neuropathology, including neuroinflammation, myelin and axonal injury and reduced neurobehavioral deficits (P < 0.05). These multi-platform studies point to impaired neurosteroidogenesis in both multiple sclerosis and experimental autoimmune encephalomyelitis. The findings also indicate that allopregnanolone and perhaps other neurosteroid-like compounds might represent potential biomarkers or therapies for multiple sclerosis.
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Affiliation(s)
- Farshid Noorbakhsh
- Department of Medicine (Neurology), 6-11 Heritage Medical Research Centre, University of Alberta, Edmonton, AB T6G 2S2, Canada
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Gan J, Greenwood SM, Cobb SR, Bushell TJ. Indirect modulation of neuronal excitability and synaptic transmission in the hippocampus by activation of proteinase-activated receptor-2. Br J Pharmacol 2011; 163:984-94. [PMID: 21366553 PMCID: PMC3130945 DOI: 10.1111/j.1476-5381.2011.01293.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 01/07/2011] [Accepted: 01/21/2011] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE Proteinase-activated receptor-2 (PAR2) is widely expressed in the CNS under normal physiological conditions. However, its potential role in modulating neuronal excitability and synaptic transmission remains to be determined. Here, we have investigated whether PAR2 activation modulates synaptic activity in the hippocampus. EXPERIMENTAL APPROACH PAR2 activation and its effect on the hippocampus were examined in rat primary cultures and acute slices using whole cell patch clamp and standard extracellular recordings, respectively. KEY RESULTS PAR2 activation leads to a depolarization of hippocampal neurones and a paradoxical reduction in the occurrence of synaptically driven spontaneous action potentials (APs). PAR2-induced neuronal depolarization was abolished following either the inhibition of astrocytic function or antagonism of ionotropic glutamate receptors whilst the PAR2-induced decrease in AP frequency was also reduced when astrocytic function was inhibited. Furthermore, when examined in acute hippocampal slices, PAR2 activation induced a profound long-term depression of synaptic transmission that was dependent on NMDA receptor activation and was sensitive to disruption of astrocytic function. CONCLUSIONS AND IMPLICATIONS These novel findings show that PAR2 activation indirectly inhibits hippocampal synaptic activity and indicate that these receptors may play an active role in modulating normal physiological CNS function, in addition to their role in pathophysiological disorders.
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Affiliation(s)
- J Gan
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
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30
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Li R, Reiser G. Phosphorylation of Ser45 and Ser59 of αB-crystallin and p38/extracellular regulated kinase activity determine αB-crystallin-mediated protection of rat brain astrocytes from C2-ceramide- and staurosporine-induced cell death. J Neurochem 2011; 118:354-64. [DOI: 10.1111/j.1471-4159.2011.07317.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Saito A, Osuga Y, Yoshino O, Takamura M, Hirata T, Hirota Y, Koga K, Harada M, Takemura Y, Yano T, Taketani Y. TGF-β1 induces proteinase-activated receptor 2 (PAR2) expression in endometriotic stromal cells and stimulates PAR2 activation-induced secretion of IL-6. Hum Reprod 2011; 26:1892-8. [PMID: 21546388 DOI: 10.1093/humrep/der125] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Proteinase-activated receptor 2 (PAR2) is a G-protein-coupled receptor that is activated by several serine proteases. PAR2 activation in endometriotic stromal cells (ESCs) has been implicated in the development of endometriosis but the regulatory mechanism of PAR2 expression in ESC is unknown. Our objective was to study the mechanism by which PAR2 expression may be regulated in endometriotic lesions. METHODS Primary cultures of ESCs were treated with transforming growth factor-β (TGF-β) 1, tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), and the expression of PAR2 was examined by real-time quantitative PCR. ESCs pretreated with or without TGF-β1 were treated with PAR2 agonist peptide (PAR2AP) and the secretion of the pro-endometriotic cytokine, IL-6, was measured using a specific enzyme-linked immunosorbent assay. Effects of TGF-β type 1 inhibitor, SB431542, and PAR2 small interfering RNA (siRNA) on the TGF-β1 stimulation of PAR2 gene expression and PAR2AP-induced IL-6 secretion were also evaluated. To study intracellular signaling, effects of inhibitors of mitogen-activated protein kinases (MAPKs) and phosphoinositide 3-kinase (PI3K) and of Smad4 siRNA on the TGF-β1-induced PAR2 gene expression were studied. RESULTS Only TGF-β1, but neither TNF-α nor IL-1β, increased gene expression of PAR2. Activation of PAR2 with PAR2AP increased the secretion of IL-6 from ESCs. As expected, TGF-β1 pretreatment dose-dependently enhanced the PAR2AP-induced increase in IL-6 secretion from ESCs. Treatment of ESCs with the TGF-β type 1 inhibitor, SB431542, inhibited both TGF-β1-stimulation of PAR2 gene expression and PAR2AP-induced IL-6 secretion. Transfection of ESCs with PAR2 siRNA produced a similar inhibition of IL-6 secretion. The TGF-β1-induced increase in PAR2 gene expression was repressed by inhibition of p38 MAPK, p42/44 MAPK or PI3K, but not by knockdown of Smad4 expression. CONCLUSIONS In view of significant roles of PAR2 and IL-6 in endometriosis, the TGF-β1-induced increase in PAR2 expression may be an elaborate mechanism that augments the progression of the disease.
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Affiliation(s)
- Ako Saito
- Department of Obstetrics and Gynecology, University of Tokyo, Tokyo, Japan
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Age- and disease-dependent HERV-W envelope allelic variation in brain: association with neuroimmune gene expression. PLoS One 2011; 6:e19176. [PMID: 21559469 PMCID: PMC3084769 DOI: 10.1371/journal.pone.0019176] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 03/22/2011] [Indexed: 12/27/2022] Open
Abstract
Background The glycoprotein, Syncytin-1, is encoded by a human endogenous retrovirus (HERV)-W env gene and is capable of inducing neuroinflammation. The specific allele(s) responsible for Syncytin-1 expression in the brain is uncertain. Herein, HERV-W env diversity together with Syncytin-1 abundance and host immune gene profiles were examined in the nervous system using a multiplatform approach. Results HERV-W env sequences were encoded by multiple chromosomal encoding loci in primary human neurons compared with less chromosomal diversity in astrocytes and microglia (p<0.05). HERV-W env RNA sequences cloned from brains of patients with systemic or neurologic diseases were principally derived from chromosomal locus 7q21.2. Within the same specimens, HERV-W env transcript levels were correlated with the expression of multiple proinflammatory genes (p<0.05). Deep sequencing of brain transcriptomes disclosed the env transcripts to be the most abundant HERV-W transcripts, showing greater expression in fetal compared with healthy adult brain specimens. Syncytin-1's expression in healthy brain specimens was derived from multiple encoding loci and linked to distinct immune and developmental gene profiles. Conclusions Syncytin-1 expression in the brain during disease was associated with neuroinflammation and was principally encoded by a full length provirus. The present studies also highlighted the diversity in HERV gene expression within the brain and reinforce the potential contributions of HERV expression to neuroinflammatory diseases.
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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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High-performance capillary electrophoresis for determining HIV-1 Tat protein in neurons. PLoS One 2011; 6:e16148. [PMID: 21249135 PMCID: PMC3017553 DOI: 10.1371/journal.pone.0016148] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Accepted: 12/09/2010] [Indexed: 11/26/2022] Open
Abstract
The HIV-1 protein, Tat has been implicated in AIDS pathogenesis however, the amount of circulating Tat is believed to be very low and its quantification has been difficult. We performed the quantification of Tat released from infected cells and taken up by neurons using high performance capillary electrophoresis. This is the first report to successfully measure the amount of Tat in neurons and places Tat as a key player involved in HIV-associated neurocognitive disorders.
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Davydova ON, Yakovlev AA, Lyzhin AA, Khaspekov LG, Gulyaeva NV. Growth factors deprivation induces a specific increase in PAR2 receptor mRNA expression in primary cerebellar cultures. NEUROCHEM J+ 2010. [DOI: 10.1134/s1819712410040069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Ashby EL, Kehoe PG, Love S. Kallikrein-related peptidase 6 in Alzheimer's disease and vascular dementia. Brain Res 2010; 1363:1-10. [PMID: 20846516 DOI: 10.1016/j.brainres.2010.09.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 09/03/2010] [Accepted: 09/06/2010] [Indexed: 11/30/2022]
Abstract
Human kallikrein-related peptidase 6 (KLK6) is highly expressed in the central nervous system. Although the physiological roles of this serine protease are unknown, in vitro substrates include amyloid precursor protein and components of the extracellular matrix, which are altered in neurological disease, particularly Alzheimer's disease (AD). We have compared KLK6 expression in post-mortem brain tissue in AD, vascular dementia (VaD) and controls. We studied the distribution of KLK6 in the temporal cortex and white matter by immunohistochemistry, and measured KLK6 mRNA and protein levels in the frontal and temporal cortex from 15 AD, 15 VaD and 15 control brains. Immunohistochemistry showed KLK6 to be restricted to endothelial cells. After adjustment for variations in vessel density by measurement of factor VIII-related antigen, we found KLK6 protein and mRNA levels to be significantly decreased in the frontal but not the temporal cortex in AD. In VaD, KLK6 protein level was significantly increased in the frontal cortex. Our findings suggest that an altered KLK6 expression may contribute to vascular abnormalities in AD and VaD.
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Affiliation(s)
- Emma L Ashby
- Dementia Research Group, Institute of Clinical Neurosciences, Clinical Science at North Bristol, University of Bristol, UK
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37
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Acharjee S, Noorbakhsh F, Stemkowski PL, Olechowski C, Cohen EA, Ballanyi K, Kerr B, Pardo C, Smith PA, Power C. HIV-1 viral protein R causes peripheral nervous system injury associated with in vivo neuropathic pain. FASEB J 2010; 24:4343-53. [PMID: 20628092 DOI: 10.1096/fj.10-162313] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Painful peripheral neuropathy has become the principal neurological disorder in HIV/AIDS patients. Herein, we investigated the effects of a cytotoxic HIV-1 accessory protein, viral protein R (Vpr), on the peripheral nervous system (PNS). Host and viral gene expression was investigated in peripheral nerves from HIV-infected individuals and in HIV-infected human dorsal root ganglion (DRG) cultures by RT-PCR and immunocytochemistry. Cytosolic calcium ([Ca(2+)]) fluxes and neuronal membrane responses were analyzed in cultured DRGs. Neurobehavioral responses and cytokine levels were assessed in a transgenic mouse model in which the vpr transgene was expressed in an immunodeficient background (vpr/RAG1(-/-)). Vpr transcripts and proteins were detected in peripheral nerves and DRGs from HIV-infected patients. Exposure of rat or human cultured DRG neurons to Vpr rapidly increased [Ca(2+)] and action potential frequency while increasing input resistance. HIV infection of human DRG cultures caused neurite retraction (P<0.05), accompanied by induction of interferon-α (IFN-α) transcripts (P<0.05). vpr/RAG1(-/-) mice expressed Vpr together with increased IFN-α (P<0.05) in the PNS and also exhibited mechanical allodynia, unlike their vpr/RAG1(-/-) littermates (P<0.05). Herein, Vpr caused DRG neuronal damage, likely through cytosolic calcium activation and cytokine perturbation, highlighting Vpr's contribution to HIV-associated peripheral neuropathy and ensuing neuropathic pain.
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Affiliation(s)
- Shaona Acharjee
- Department of Medicine,University of Alberta, Edmonton, AB, Canada
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Abstract
Individuals suffering from human immunodeficiency virus type 1 (HIV-1) infection suffer from a wide range of neurological deficits. The most pronounced are the motor and cognitive deficits observed in many patients in the latter stages of HIV infection. Gross postmortem inspection shows cortical atrophy and widespread
neuronal loss. One of the more debilitating of the HIV-related syndromes is AIDS-related dementia, or HAD. Complete understanding of HIV neurotoxicity has been elusive. Both direct and indirect toxic mechanisms have been implicated in the neurotoxicity of the
HIV proteins, Tat and gp120. The glutamatergic system, nitric oxide, calcium, oxidative stress, apoptosis, and microglia have all been implicated in the pathogenesis of HIV-related neuronal degeneration. The aim of this review is to summarize the most
recent work and provide an overview to the current theories of HIV-related neurotoxicity and potential avenues of therapeutic interventions to prevent the neuronal loss and motor/cognitive deficits previously described.
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Affiliation(s)
- David R. Wallace
- Department of Pharmacology and Physiology and Department of Forensic Sciences, Center for Health Sciences, Oklahoma State University, Tulsa, OK 74107-1898, USA
- *David R. Wallace:
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Greenwood SM, Bushell TJ. Astrocytic activation and an inhibition of MAP kinases are required for proteinase-activated receptor-2-mediated protection from neurotoxicity. J Neurochem 2010; 113:1471-80. [PMID: 20402964 DOI: 10.1111/j.1471-4159.2010.06737.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Proteinase-activated receptor-2 (PAR-2) expression levels are altered in several CNS disorders with these changes being proposed to either exacerbate or diminish the disease state depending on the cell type in which this occurs. Here we present data investigating the consequence of PAR-2 activation on kainate (KA)-induced neurotoxicity in organotypic hippocampal slices cultures (OHSC). Exposure of OHSC to the PAR-2 activators trypsin or Ser-Leu-Ile-Gly-Arg-Leu (SLIGRL) induced no neurotoxicity when applied alone but was neuroprotective against KA-induced neurotoxicity. SLIGRL-mediated neuroprotection involved astrocytic activation as the neuroprotective effect was abolished following OHSC pre-treatment with fluoroacetate. Moreover, co-application of either reparixin or LY341495, antagonists of the CXCR2 chemokine receptor and metabotropic glutamate receptors respectively, inhibited the SLIGRL-mediated neuroprotection. SLIGRL application inhibited both p38 MAPK and ERK activity in OHSC, but not the JNK 1/2 signalling pathway. Accordingly, the co-application of the p38 MAPK and ERK inhibitors SB203580 and UO126 reduced KA-induced cell death, mimicking PAR-2-mediated neuroprotection. These data indicate that PAR-2 activation is neuroprotective and involves astrocytic activation, gliotransmitter release, and the subsequent inhibition of MAPK signalling cascades, providing further evidence for PAR-2 as an interesting therapeutic target in certain CNS disorders.
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Affiliation(s)
- Sam M Greenwood
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
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40
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Davydova ON, Yakovlev AA. Protease-activated receptors and neuroplasticity: Protease-activated receptors as a possible target for cathepsin B. NEUROCHEM J+ 2010. [DOI: 10.1134/s1819712410010010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Lam DK, Schmidt BL. Serine proteases and protease-activated receptor 2-dependent allodynia: a novel cancer pain pathway. Pain 2010; 149:263-272. [PMID: 20189717 DOI: 10.1016/j.pain.2010.02.010] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 02/05/2010] [Accepted: 02/05/2010] [Indexed: 10/19/2022]
Abstract
Mediators involved in the generation of pain in patients with cancer are poorly understood. Using a combined molecular, pharmacologic, behavioral, and genetic approach, we have identified a novel mechanism of cancer-dependent allodynia induced by protease-activated receptor 2 (PAR2). Here we show that human head and neck carcinoma cells have increased levels of proteolytic activity compared to normal human cell controls. Supernatant from human carcinoma cells, but not controls, caused marked and prolonged mechanical allodynia in mice, when administered into the hindpaw. This nociceptive effect was abolished by serine protease inhibition, diminished by mast cell depletion and absent in PAR2-deficient mice. In addition, non-contact co-culture of trigeminal ganglion neurons with human head and neck carcinoma cells increased the proportion of neurons that exhibited PAR2-immunoreactivity. Our results point to a direct role for serine proteases and their receptor in the pathogenesis of cancer pain. This previously unrecognized cancer pain pathway has important therapeutic implications wherein serine protease inhibitors and PAR2 antagonists may be useful for the treatment of cancer pain.
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Affiliation(s)
- D K Lam
- Department of Oral and Maxillofacial Surgery, University of California - San Francisco, San Francisco, CA, USA
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Noorbakhsh F, Ramachandran R, Barsby N, Ellestad KK, LeBlanc A, Dickie P, Baker G, Hollenberg MD, Cohen EA, Power C. MicroRNA profiling reveals new aspects of HIV neurodegeneration: caspase-6 regulates astrocyte survival. FASEB J 2010; 24:1799-812. [PMID: 20097875 DOI: 10.1096/fj.09-147819] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
MicroRNAs (miRNAs) are small noncoding RNA molecules, which are known to regulate gene expression in physiological and pathological conditions. miRNA profiling was performed using brain tissue from patients with HIV encephalitis (HIVE), a neuroinflammatory/degenerative disorder caused by HIV infection of the brain. Microarray analysis showed differential expression of multiple miRNAs in HIVE compared to control brains. Target prediction and gene ontology enrichment analysis disclosed targeting of several gene families/biological processes by differentially expressed miRNAs (DEMs), with cell death-related genes, including caspase-6, showing a bias toward down-regulated DEMs. Consistent with the miRNA data, HIVE brains exhibited higher levels of caspase-6 transcripts compared with control patients. Immunohistochemical analysis showed localization of the cleaved form of caspase-6 in astrocytes in HIVE brain sections. Exposure of cultured human primary astrocytes to HIV viral protein R (Vpr) induced p53 up-regulation, loss of mitochondrial membrane potential, and caspase-6 activation followed by cell injury. Transgenic mice, expressing Vpr in microglial cells, demonstrated astrocyte apoptosis in brain, which was associated with caspase-6 activation and neurobehavioral abnormalities. Overall, these data point to previously unrecognized alterations in miRNA profile in the brain during HIV infection, which contribute to cell death through dysregulation of cell death machinery.
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Affiliation(s)
- Farshid Noorbakhsh
- Department of Medicine (Neurology), University of Alberta, Edmonton, AB, Canada
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Maingat F, Viappiani S, Zhu Y, Vivithanaporn P, Ellestad KK, Holden J, Silva C, Power C. Regulation of lentivirus neurovirulence by lipopolysaccharide conditioning: suppression of CXCL10 in the brain by IL-10. THE JOURNAL OF IMMUNOLOGY 2009; 184:1566-74. [PMID: 20042580 DOI: 10.4049/jimmunol.0902575] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Lentivirus infections including HIV and feline immunodeficiency virus (FIV) cause neurovirulence, which is largely mediated by innate immunity. To investigate the interactions between neurovirulence and repeated conditioning by innate immune activation, models of lentivirus infection were exposed to LPS. Gene expression in HIV-infected (HIV+) and control (HIV-) patient brains was compared by real time RT-PCR and immunocytochemistry. Supernatants from mock and HIV-infected monocyte-derived macrophages exposed to LPS were applied to human neurons. FIV-infected (FIV+) and control (FIV-) animals were exposed repeatedly to LPS postinfection together with concurrent neurobehavioral testing, viral load, and host gene analyses. Brains from HIV+ individuals exhibited induction of CD3epsilon, CXCL10, and granzyme A expression (p < 0.05). Supernatants from HIV+ monocyte-derived macrophages induced CXCL10 expression in neurons, which was diminished by IL-10 treatment (p < 0.05). LPS-exposed FIV+ animals demonstrated lower plasma and brain viral loads (p < 0.05). Neuronal CXCL10 expression was increased in FIV+ animals but was suppressed by LPS exposure, together with reduced brain CD3epsilon and granzyme A expression (p < 0.05). In conjunction with preserved NeuN-positive neuronal counts in parietal cortex (p < 0.05), FIV+ animals exposed to LPS also showed less severe neurobehavioral deficits (p < 0.05). Repeated LPS exposures suppressed CXCL10 in the brain and ensuing T cell infiltration with a concomitant reduction in neurovirulence. Thus, innate immune chronic conditioning exerted beneficial effects on neurovirulence through suppression of a specific chemotactic factor, CXCL10, mediated by IL-10, leading to reduced leukocyte infiltration and release of neurotoxic factors.
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Lohman RJ, Jones NC, O’Brien TJ, Cocks TM. A regulatory role for protease-activated receptor-2 in motivational learning in rats. Neurobiol Learn Mem 2009; 92:301-9. [DOI: 10.1016/j.nlm.2009.03.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 02/19/2009] [Accepted: 03/25/2009] [Indexed: 11/25/2022]
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Jian C, Wenjuan H, Huaizhen R. Protease-activated receptors in neuropathic pain: an important mediator between neuron and glia. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/s1000-1948(09)60045-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Li R, Rohatgi T, Hanck T, Reiser G. Alpha A-crystallin and alpha B-crystallin, newly identified interaction proteins of protease-activated receptor-2, rescue astrocytes from C2-ceramide- and staurosporine-induced cell death. J Neurochem 2009; 110:1433-44. [PMID: 19558454 DOI: 10.1111/j.1471-4159.2009.06226.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protease-activated receptor-2 (PAR-2) is a G protein-coupled receptor activated by trypsin and other trypsin-like serine proteases. The widely expressed PAR-2 is involved in inflammation response but the physiological/pathological roles of PAR-2 in the nervous system are still uncertain. In the present study, we report novel PAR-2 interaction proteins, alphaA-crystallin and alphaB-crystallin. These 20 kDa proteins have been implicated in neurodegenerative diseases like Alexander's disease, Creutzfeldt-Jacob disease, Alzheimer's disease, and Parkinson's disease. Results from yeast two-hybrid assay using the cytoplasmic C-tail of PAR-2 as bait suggested that alphaA-crystallin interacts with PAR-2. We further demonstrate the in vitro and cellular in vivo interaction of C-tail of PAR-2 as well as of full-length PAR-2 with alphaA(alphaB)-crystallins. We use pull-down, co-immunoprecipitation, and co-localization assays. Analysis of alphaA-crystallin deletion mutants showed that amino acids 120-130 and 136-154 of alphaA-crystallin are required for the interaction with PAR-2. Co-immunoprecipitation experiments ruled out an interaction of alphaA(alphaB)-crystallins with PAR-1, PAR-3, and PAR-4. This demonstrates that alphaA(alphaB)-crystallins are PAR-2-specific interaction proteins. Moreover, we investigated the functional role of PAR-2 and alpha-crystallins in astrocytes. Evidence is presented to show that PAR-2 activation and increased expression of alpha-crystallins reduced C2-ceramide- and staurosporine-induced cell death in astrocytes. Thus, both PAR-2 and alpha-crystallins are involved in cytoprotection in astrocytes.
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Affiliation(s)
- Rongyu Li
- Medizinische Fakultät, Institut für Neurobiochemie, Otto-von-Guericke-Universität Magdeburg, Magdeburg 39120, Germany
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Essential role of mitogen-activated protein kinase pathways in protease activated receptor 2-mediated nitric-oxide production from rat primary astrocytes. Nitric Oxide 2009; 21:110-9. [PMID: 19527794 DOI: 10.1016/j.niox.2009.05.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Revised: 05/20/2009] [Accepted: 05/26/2009] [Indexed: 11/24/2022]
Abstract
Protease-activated receptors (PARs) play important roles in the regulation of brain function such as neuroinflammation by transmitting the signal from proteolytic enzymes such as thrombin and trypsin. We and others have reported that a member of the family, PAR-2 is activated by trypsin, whose involvement in the neurophysiological process is increasingly evident, and is involved in the neuroinflammatory processes including morphological changes of astrocytes. In this study, we investigated the role of PAR-2 in the production of nitric oxide (NO) in rat primary astrocytes. Treatment of PAR-2 agonist trypsin increased NO production in a dose-dependent manner, which was mediated by the induction of inducible nitric-oxide synthase. The trypsin-mediated production of NO was mimicked by PAR-2 agonist peptide and reduced by either pharmacological PAR-2 antagonist peptide or by siRNA-mediated inhibition of PAR-2 expression, which suggests the critical role of PAR-2 in this process. NO production by PAR-2 was mimicked by PMA, a PKC activator, and was attenuated by Go6976, a protein kinase C (PKC) inhibitor. PAR-2 stimulation activated three subtypes of mitogen-activated protein kinases (MAPKs): extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 MAPK. NO production by PAR-2 was blocked by inhibition of ERK, p38, and JNK pathways. PAR-2 stimulation also activated nuclear factor-kappaB (NF-kappaB) DNA binding and transcriptional activity as well as IkappaBalpha phosphorylation. Inhibitors of NF-kappaB pathway inhibited PAR-2-mediated NO production. In addition, inhibitors of MAPK pathways prevented transcriptional activation of NF-kappaB reporter constructs. These results suggest that PAR-2 activation-mediated NO production in astrocytes is transduced by the activation of MAPKs followed by NF-kappaB pathways.
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Christerson U, Keita AV, Söderholm JD, Gustafson-Svärd C. Increased expression of protease-activated receptor-2 in mucosal mast cells in Crohn's ileitis. J Crohns Colitis 2009; 3:100-8. [PMID: 21172252 DOI: 10.1016/j.crohns.2008.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 11/04/2008] [Accepted: 11/05/2008] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND AIMS Activation of protease-activated receptor-2 (PAR-2) may stimulate various events of importance in inflammatory processes, including release of inflammatory mast cell mediators. PAR-2 is frequently up-regulated during inflammatory conditions, but it is not known if the expression is altered in Crohn's disease. The aim of the present study was to investigate the ileal mucosal PAR-2 expression in Crohn's ileitis, with particular emphasis on the expression in ileal mucosal mast cells. METHODS Surgical specimens from the distal ileum were collected from patients with Crohn's ileitis and patients with colonic cancer as controls. The overall expression of PAR-2 was investigated by Western blot, and the presence of PAR-2 expressing mucosal mast cells by immunohistochemistry and cell counting. The effect of tumor necrosis factor-α (TNF-α) on the PAR-2 expression in a human mast cell line (HMC-1) was investigated by RT-PCR and immunocytochemistry. RESULTS In Crohn's specimens, the fraction of PAR-2-expressing mucosal mast cells was increased about 2.5 times (P<0.001; n=14) compared with specimens from control patients (n=6). No difference was found between inflamed (n=6) and uninflamed Crohn's specimens (P>0.05; n=8). Exposure to TNF-α for 48 h up-regulated PAR-2 mRNA and protein expression in the HMC-1 cell line. CONCLUSION PAR-2 is up-regulated on ileal mucosal mast cells in Crohn's ileitis, possibly due to the action of inflammatory cytokines, such as TNF-α. This may contribute to perpetuating the inflammatory process in the intestinal mucosa in Crohn's ileitis.
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Affiliation(s)
- Ulrika Christerson
- School of Pure and Applied Natural Sciences, University of Kalmar, SE-391 82 Kalmar, Sweden
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Protease-activated receptors as drug targets in inflammation and pain. Pharmacol Ther 2009; 123:292-309. [PMID: 19481569 DOI: 10.1016/j.pharmthera.2009.05.004] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Accepted: 05/05/2009] [Indexed: 12/12/2022]
Abstract
Proteases have been shown to signal to cells through the activation of a novel class of receptors coupled to G proteins: the protease-activated receptors (PARs). Those receptors are expressed in a wide range of cells, which ultimately are all involved in mechanisms of inflammation and pain. Numerous studies have considered the role of PARs in cells, organ systems or in vivo, highlighting the fact that PAR activation results in signs of inflammation. A growing body of evidences discussed here suggests that these receptors, and the proteases that activate them, interfere with inflammation and pain processes. Whether a role for PARs has been clearly defined in inflammatory and pain pathologies is discussed in this review. Further, the pros and cons for considering PARs as targets for the development of therapeutic options for the treatment of inflammation and pain are discussed.
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Zhu Y, Vergote D, Pardo C, Noorbakhsh F, McArthur JC, Hollenberg MD, Overall CM, Power C. CXCR3 activation by lentivirus infection suppresses neuronal autophagy: neuroprotective effects of antiretroviral therapy. FASEB J 2009; 23:2928-41. [PMID: 19380511 DOI: 10.1096/fj.08-128819] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Previous studies have implicated CXCL12 in the neuropathogenesis of HIV infection. Proteolysis of CXCL12 generates a neurotoxic molecule, CXCL12(5-67), which engages and activates CXCR3, in addition to exhibiting increased expression in the brains of patients with HIV-associated dementia (HAD). Herein, we investigated CXCR3-mediated neuronal injury, particularly, its contribution to autophagy suppression and the concomitant effects of antiretroviral therapy using human brain samples and models of HIV neuropathogenesis. Neurons in the brains of HAD patients and feline immunodeficiency virus (FIV)-infected animals, as well as cultured human neurons, expressed CXCR3, which was modulated in a ligand-specific manner. Exposure of human neurons to CXCL12(5-67) caused a reduction in the autophagy-associated molecule LC3 (P<0.05) and neuronal survival (P<0.05), which recapitulated findings in FIV- and HIV-infected brains (P<0.05). Oral didanosine (ddI) treatment of FIV-infected animals reduced neurobehavioral abnormalities in conjunction with diminished plasma viral load (P<0.05). F4/80 transcript abundance and CXCL12(5-67) immunoreactivity were reduced with restored neuronal LC3 expression in the brains of FIV-infected animals after ddI treatment (P<0.05). ddI treatment also prevented microglial activation and depletion of synaptic proteins in the cortex of FIV-infected animals (P<0.05). These findings indicate that the beneficial effects of ddI might be a consequence of a reduced systemic viral burden and concurrent leukocyte activation, leading to diminished neuroinflammation with preservation of neuronal autophagy by regulating CXCR3 activation.
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Affiliation(s)
- Yu Zhu
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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