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Ji B, Ma Y, Wang H, Fang X, Shi P. Activation of the P38/CREB/MMP13 axis is associated with osteoarthritis. DRUG DESIGN DEVELOPMENT AND THERAPY 2019; 13:2195-2204. [PMID: 31308631 PMCID: PMC6613348 DOI: 10.2147/dddt.s209626] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/04/2019] [Indexed: 12/27/2022]
Abstract
Purposes Osteoarthritis (OA) is a common joint disease characterized by the degradation of articular cartilage and joint inflammation. Interleukin-1ß induces P38/cAMP response element binding protein (CREB) pathway activation, resulting in increased expression of matrix metallopeptidase-13 (MMP13) in chondrocytes. However, the role of the P38/CREB/MMP13 axis is unclear in the progression of OA. In this study, we aimed to answer the following questions: (1) how does the P38/CREB/MMP13 axis in cartilage from patients with OA compare with control specimens? (2) Can the P38 agonist anisomycin (ANS) induce mouse OA? Materials and methods Surgical specimens of human cartilage were divided into OA and control groups. Surgical specimens of mouse cartilage were divided into control and ANS-induced groups. Safranin O staining of the cartilage tissues was performed to evaluate the extracellular matrix. Reverse transcription-polymerase chain reaction was performed using these tissues to investigate messenger RNA expressions of type II collagen, aggrecan, MMP13, and ADAM metallopeptidase with thrombospondin type 1 motif 5. Phosphorylated (p)-P38, p-CREB, and MMP13 were evaluated by Western blot analysis. Anisomycin was used to activate P38, and p-P38, p-CREB, and MMP13 were evaluated by immunofluorescence and Western blot analysis. Results Safranin O staining showed that the extracellular matrix degraded in humans with OA and ANS-induced mouse cartilage samples. The expressions of p-P38, p-CREB, and MMP13 were all upregulated in osteoarthritic cartilage or anisomycin-induced chondrocytes, suggesting that the P38/CREB/MMP13 axis may play a role in the progression of OA. Conclusions The P38/CREB/MMP13 axis is active in osteoarthritic chondrocytes and may cause the degeneration of cartilage. Effective new therapy directed against this pathway could be developed.
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Affiliation(s)
- Bin Ji
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Medical College of Zhejiang University, Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, Zhejiang Province 310016, People's Republic of China.,Department of Orthopaedic Surgery, First Affiliated Hospital of Jiaxing University, Jiaxing, Zhejiang Province 314000, People's Republic of China
| | - Yan Ma
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Medical College of Zhejiang University, Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, Zhejiang Province 310016, People's Republic of China
| | - Haimin Wang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Medical College of Zhejiang University, Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, Zhejiang Province 310016, People's Republic of China.,Orthopedics Department, Taizhou Bo Ai Hospital, Taizhou, Zhejiang Province 318050, People's Republic of China
| | - Xiangqian Fang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Medical College of Zhejiang University, Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, Zhejiang Province 310016, People's Republic of China
| | - Peihua Shi
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Medical College of Zhejiang University, Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Hangzhou, Zhejiang Province 310016, People's Republic of China
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Park J, Jang JH, Kim JH. Mediatory role of BLT2 in the proliferation of KRAS mutant colorectal cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:329-336. [PMID: 30553812 DOI: 10.1016/j.bbamcr.2018.12.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 11/22/2018] [Accepted: 12/09/2018] [Indexed: 02/02/2023]
Abstract
Inflammatory lipid mediators play various roles in colorectal cancer progression through complex pathways. However, the mechanism by which lipoxygenase-derived inflammatory lipid mediators contribute to colorectal cancer progression remains elusive. In this study, we found that BLT2, a cell surface GPCR for leukotriene B4 and 12‑hydroxyeicosatetraenoic acid, is highly upregulated in KRAS mutant LOVO and SW480 colorectal cancer cells and plays critical roles in mediating proliferation through activation of phosphatidylinositol 3‑kinase (PI3K)/protein kinase B (Akt) and subsequent upregulation of cyclin D1. Exposure to BLT2 siRNA or LY255283, a specific BLT2 inhibitor, clearly suppressed the proliferation of KRAS mutant colorectal cancer cells and markedly increased cell cycle arrest by downregulating the PI3K/Akt-cyclin D1 cascade. Xenograft tumor formation by LOVO and SW480 cells in athymic mice was also substantially reduced by treatment with the BLT2 inhibitor in vivo. Together, our study demonstrates that BLT2 is necessary for the proliferation of LOVO and SW480 cells and thus may be a potential therapeutic target for the treatment of KRAS mutant colorectal cancer.
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Affiliation(s)
- JaeIn Park
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea
| | - Jae-Hyun Jang
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea
| | - Jae-Hong Kim
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
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Wang SH, Wang SC, Chen PC, Wang ST, Liu YW. Induction of cyclooxygenase-2 gene by Candida albicans through EGFR, ERK, and p38 pathways in human urinary epithelium. Med Mycol 2017; 55:314-322. [PMID: 27664170 DOI: 10.1093/mmy/myw082] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 06/15/2016] [Indexed: 12/26/2022] Open
Abstract
In the present data, we found that Candida albicans (C. albicans) caused bladder epithelial cell morphology alteration, cell damage, and inflammatory responses, including cyclooxygenase-2 (COX-2) gene and protein expression as well as prostaglandin E2 accumulation. In addition, the molecular pathway underlying C. albicans-induced urothelial COX-2 gene expression was examined. Among MAPK pathways, phosphorylation of ERK1/2, p38, and JNK each increased following C. albicans infection for 12 h. However, C. albicans-induced COX-2 protein expression was inhibited by specific inhibitors of ERK and p38 (U0126 and SB203580) but not by JNK inhibitor SP600125. Additional evidence came from the increased amount of phosphorylated RSK that is the mutual downstream molecule of ERK1/2 and p38. Furthermore, phosphorylation of RSK protein was reduced by the ERK and p38 inhibitor, suggesting that the urothelial COX-2 gene was induced majorly though the ERK/p38-RSK pathway by C. albicans infection. We also found transcription factor CREB-1 showed increased binding to the COX-2 gene promoter by chromatin immunoprecipitation assay. Next, we used receptor inhibitors including Toll-like receptor (TLR)-Myd88 inhibitor ST2825, Dectin-Syk inhibitor Syk inhibitor, and epidermal growth factor receptor (EGFR) inhibitor PD168393 to identify which one was the main target associated with C. albicans binding. The results revealed that it was EGFR, recognized by C. albicans, that mostly mediated the ERK/p38-RSK pathway activation to induce COX-2 gene expression, but this was not the case for TLRs and Dectin receptors. In summary, these results demonstrated the EGFR-ERK/p38-RSK-CREB-1 pathway was involved significantly in the C. albicans-induced COX-2 expression in human urothelium.
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Affiliation(s)
- Shao-Hung Wang
- Department of Microbiology, Immunology and Biopharmaceuticals; College of Life Sciences, National Chiayi University, Chiayi 600, Taiwan
| | - Shou-Chieh Wang
- Division of Nephrology, Department of Internal Medicine, Kuang Tien General Hospital, Taichung 437, Taiwan.,Department of Food Science; College of Life Sciences, National Chiayi University, Chiayi 600, Taiwan
| | - Pei-Ching Chen
- Department of Microbiology, Immunology and Biopharmaceuticals; College of Life Sciences, National Chiayi University, Chiayi 600, Taiwan
| | - Shou-Tsung Wang
- Department of Food Science; College of Life Sciences, National Chiayi University, Chiayi 600, Taiwan
| | - Yi-Wen Liu
- Department of Microbiology, Immunology and Biopharmaceuticals; College of Life Sciences, National Chiayi University, Chiayi 600, Taiwan
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Marshall P, Bredy TW. Cognitive neuroepigenetics: the next evolution in our understanding of the molecular mechanisms underlying learning and memory? NPJ SCIENCE OF LEARNING 2016; 1:16014. [PMID: 27512601 PMCID: PMC4977095 DOI: 10.1038/npjscilearn.2016.14] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
A complete understanding of the fundamental mechanisms of learning and memory continues to elude neuroscientists. Although many important discoveries have been made, the question of how memories are encoded and maintained at the molecular level remains. To date, this issue has been framed within the context of one of the most dominant concepts in molecular biology, the central dogma, and the result has been a protein-centric view of memory. Here we discuss the evidence supporting a role for neuroepigenetic mechanisms, which constitute dynamic and reversible, state-dependent modifications at all levels of control over cellular function, and their role in learning and memory. This neuroepigenetic view suggests that DNA, RNA and protein each influence one another to produce a holistic cellular state that contributes to the formation and maintenance of memory, and predicts a parallel and distributed system for the consolidation, storage and retrieval of the engram.
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Affiliation(s)
- Paul Marshall
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA, USA
| | - Timothy W Bredy
- Department of Neurobiology and Behavior and Center for the Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA, USA
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
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Saeki T, Inui H, Fujioka S, Fukuda S, Nomura A, Nakamura Y, Park EY, Sato K, Kanamoto R. Staurosporine synergistically potentiates the deoxycholate-mediated induction of COX-2 expression. Physiol Rep 2014; 2:2/8/e12143. [PMID: 25168879 PMCID: PMC4246598 DOI: 10.14814/phy2.12143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Colorectal cancer is a major cause of cancer‐related death in western countries, and thus there is an urgent need to elucidate the mechanism of colorectal tumorigenesis. A diet that is rich in fat increases the risk of colorectal tumorigenesis. Bile acids, which are secreted in response to the ingestion of fat, have been shown to increase the risk of colorectal tumors. The expression of cyclooxygenase (COX)‐2, an inducible isozyme of cyclooxygenase, is induced by bile acids and correlates with the incidence and progression of cancers. In this study, we investigated the signal transduction pathways involved in the bile‐acid‐mediated induction of COX‐2 expression. We found that staurosporine (sts), a potent protein kinase C (PKC) inhibitor, synergistically potentiated the deoxycholate‐mediated induction of COX‐2 expression. Sts did not increase the stabilization of COX‐2 mRNA. The sts‐ and deoxycholate‐mediated synergistic induction of COX‐2 expression was suppressed by a membrane‐permeable Ca2+ chelator, a phosphoinositide 3‐kinase inhibitor, a nuclear factor‐κB pathway inhibitor, and inhibitors of canonical and stress‐inducible mitogen‐activated protein kinase pathways. Inhibition was also observed using PKC inhibitors, suggesting the involvement of certain PKC isozymes (η, θ, ι, ζ, or μ). Our results indicate that sts exerts its potentiating effects via the phosphorylation of p38. However, the effects of anisomycin did not mimic those of sts, indicating that although p38 activation is required, it does not enhance deoxycholate‐induced COX‐2 expression. We conclude that staurosporine synergistically enhances deoxycholate‐induced COX‐2 expression in RCM‐1 colon cancer cells. e12143 The expression of COX‐2, an inducible isozyme of cyclooxygenase, correlates with the incidence and progression of cancers, and bile acids have been shown to induce COX‐2 expression. We investigated the signal transduction pathways involved in the bile‐acid‐mediated induction of COX‐2 expression, and we found that staurosporine, a potent PKC inhibitor, synergistically potentiated the deoxycholate‐mediated induction of COX‐2 expression. Staurosporine exerted its potentiating effects via the phosphorylation of p38, and the involvement of certain PKC isozymes was suggested.
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Affiliation(s)
- Tohru Saeki
- Laboratory of Molecular Nutrition, Kyoto Prefectural University, Kyoto, Japan
| | - Haruka Inui
- Laboratory of Molecular Nutrition, Kyoto Prefectural University, Kyoto, Japan
| | - Saya Fujioka
- Laboratory of Molecular Nutrition, Kyoto Prefectural University, Kyoto, Japan
| | - Suguru Fukuda
- Laboratory of Molecular Nutrition, Kyoto Prefectural University, Kyoto, Japan
| | - Ayumi Nomura
- Laboratory of Molecular Nutrition, Kyoto Prefectural University, Kyoto, Japan
| | - Yasushi Nakamura
- Laboratory of Food Science, Kyoto Prefectural University, Kyoto, Japan
| | - Eun Young Park
- Laboratory of Food Science, Kyoto Prefectural University, Kyoto, Japan
| | - Kenji Sato
- Laboratory of Food Science, Kyoto Prefectural University, Kyoto, Japan
| | - Ryuhei Kanamoto
- Laboratory of Molecular Nutrition, Kyoto Prefectural University, Kyoto, Japan
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Albumin-induced podocyte injury and protection are associated with regulation of COX-2. Kidney Int 2014; 86:1150-60. [PMID: 24918154 PMCID: PMC4245399 DOI: 10.1038/ki.2014.196] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 03/26/2014] [Accepted: 04/03/2014] [Indexed: 01/11/2023]
Abstract
Albuminuria is both a hallmark and a risk factor for progressive glomerular disease, and results in increased exposure of podocytes to serum albumin with its associated factors. Here in vivo and in vitro models of serum albumin overload were used to test the hypothesis that albumin-induced proteinuria and podocyte injury directly correlate with COX-2 induction. Albumin induced COX-2, MCP-1, CXCL1 and the stress protein HSP25 in both rat glomeruli and cultured podocytes, while B7-1 and HSP70i were also induced in podocytes. Podocyte exposure to albumin induced both mRNA and protein and enhanced the mRNA stability of COX-2, a key regulator of renal hemodynamics and inflammation, which renders podocytes susceptible to injury. Podocyte exposure to albumin also stimulated several kinases (p38 MAPK, MK2, JNK/SAPK and ERK1/2), inhibitors of which (except JNK/SAPK) down-regulated albumin-induced COX-2. Inhibition of AMPK, PKC and NFκB also down-regulated albumin-induced COX-2. Critically, albumin-induced COX-2 was also inhibited by glucocorticoids and thiazolidinediones, both of which directly protect podocytes against injury. Furthermore, specific albumin-associated fatty acids were identified as important contributors to COX-2 induction, podocyte injury and proteinuria. Thus, COX-2 is associated with podocyte injury during albuminuria, as well as with the known podocyte protection imparted by glucocorticoids and thiazolidinediones. Moreover, COX-2 induction, podocyte damage and albuminuria appear mediated largely by serum albumin-associated fatty acids.
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Okine BN, Norris LM, Woodhams S, Burston J, Patel A, Alexander SPH, Barrett DA, Kendall DA, Bennett AJ, Chapman V. Lack of effect of chronic pre-treatment with the FAAH inhibitor URB597 on inflammatory pain behaviour: evidence for plastic changes in the endocannabinoid system. Br J Pharmacol 2012; 167:627-40. [PMID: 22595021 PMCID: PMC3449266 DOI: 10.1111/j.1476-5381.2012.02028.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 04/19/2012] [Accepted: 04/25/2012] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Elevating levels of endocannabinoids with inhibitors of fatty acid amide hydrolase (FAAH) is a major focus of pain research, purported to be a safer approach devoid of cannabinoid receptor-mediated side effects. Here, we have determined the effects of sustained pharmacological inhibition of FAAH on inflammatory pain behaviour and if pharmacological inhibition of FAAH was as effective as genetic deletion of FAAH on pain behaviour. EXPERIMENTAL APPROACH Effects of pre-treatment with a single dose, versus 4 day repeated dosing with the selective FAAH inhibitor, URB597 (i.p. 0.3 mg·kg⁻¹), on carrageenan-induced inflammatory pain behaviour and spinal pro-inflammatory gene induction were determined in rats. Effects of pain induction and of the drug treatments on levels of arachidonoyl ethanolamide (AEA), palmitoyl ethanolamide (PEA) and oleolyl ethanolamide (OEA) in the spinal cord were determined. KEY RESULTS Single, but not repeated, URB597 treatment significantly attenuated the development of inflammatory hyperalgesia (P < 0.001, vs. vehicle-treated animals). Neither mode of URB597 treatment altered levels of AEA, PEA and OEA in the hind paw, or carrageenan-induced paw oedema. Single URB597 treatment produced larger increases in AEA, PEA and OEA in the spinal cord, compared with those after repeated administration. Single and repeated URB597 treatment decreased levels of immunoreactive N-acylphosphatidylethanolamine phospholipase D (NAPE-PLD) in the spinal cord and attenuated carrageenan-induced spinal pro-inflammatory gene induction. CONCLUSION AND IMPLICATIONS Changes in the endocannabinoid system may contribute to the loss of analgesic effects following repeated administration of low dose URB597 in this model of inflammatory pain.
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Affiliation(s)
- Bright N Okine
- School of Biomedical Sciences, University of Nottingham, Queen's Medical CentreNottingham, UK
| | - Leonie M Norris
- School of Biomedical Sciences, University of Nottingham, Queen's Medical CentreNottingham, UK
- Centre for Analytical Bioscience, School of Pharmacy, University of NottinghamNottingham, UK
| | - Stephen Woodhams
- School of Biomedical Sciences, University of Nottingham, Queen's Medical CentreNottingham, UK
| | - James Burston
- School of Biomedical Sciences, University of Nottingham, Queen's Medical CentreNottingham, UK
- Arthritis Research UK Pain Centre, School of Biomedical Sciences, University of NottinghamNottingham, UK
| | - Annie Patel
- School of Biomedical Sciences, University of Nottingham, Queen's Medical CentreNottingham, UK
| | - Stephen PH Alexander
- School of Biomedical Sciences, University of Nottingham, Queen's Medical CentreNottingham, UK
| | - David A Barrett
- Centre for Analytical Bioscience, School of Pharmacy, University of NottinghamNottingham, UK
| | - David A Kendall
- School of Biomedical Sciences, University of Nottingham, Queen's Medical CentreNottingham, UK
| | - Andrew J Bennett
- School of Biomedical Sciences, University of Nottingham, Queen's Medical CentreNottingham, UK
| | - Victoria Chapman
- School of Biomedical Sciences, University of Nottingham, Queen's Medical CentreNottingham, UK
- Arthritis Research UK Pain Centre, School of Biomedical Sciences, University of NottinghamNottingham, UK
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Sagar DR, Burston JJ, Hathway GJ, Woodhams SG, Pearson RG, Bennett AJ, Kendall DA, Scammell BE, Chapman V. The contribution of spinal glial cells to chronic pain behaviour in the monosodium iodoacetate model of osteoarthritic pain. Mol Pain 2011; 7:88. [PMID: 22093915 PMCID: PMC3271989 DOI: 10.1186/1744-8069-7-88] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 11/17/2011] [Indexed: 12/31/2022] Open
Abstract
Background Clinical studies of osteoarthritis (OA) suggest central sensitization may contribute to the chronic pain experienced. This preclinical study used the monosodium iodoacetate (MIA) model of OA joint pain to investigate the potential contribution of spinal sensitization, in particular spinal glial cell activation, to pain behaviour in this model. Experimental OA was induced in the rat by the intra-articular injection of MIA and pain behaviour (change in weight bearing and distal allodynia) was assessed. Spinal cord microglia (Iba1 staining) and astrocyte (GFAP immunofluorescence) activation were measured at 7, 14 and 28 days post MIA-treatment. The effects of two known inhibitors of glial activation, nimesulide and minocycline, on pain behaviour and activation of microglia and astrocytes were assessed. Results Seven days following intra-articular injection of MIA, microglia in the ipsilateral spinal cord were activated (p < 0.05, compared to contralateral levels and compared to saline controls). Levels of activated microglia were significantly elevated at day 14 and 21 post MIA-injection. At day 28, microglia activation was significantly correlated with distal allodynia (p < 0.05). Ipsilateral spinal GFAP immunofluorescence was significantly (p < 0.01) increased at day 28, but not at earlier timepoints, in the MIA model, compared to saline controls. Repeated oral dosing (days 14-20) with nimesulide attenuated pain behaviour and the activation of microglia in the ipsilateral spinal cord at day 21. This dosing regimen also significantly attenuated distal allodynia (p < 0.001) and numbers of activated microglia (p < 0.05) and GFAP immunofluorescence (p < 0.001) one week later in MIA-treated rats, compared to vehicle-treated rats. Repeated administration of minocycline also significantly attenuated pain behaviour and reduced the number of activated microglia and decreased GFAP immunofluorescence in ipsilateral spinal cord of MIA treated rats. Conclusions Here we provide evidence for a contribution of spinal glial cells to pain behaviour, in particular distal allodynia, in this model of osteoarthritic pain. Our data suggest there is a potential role of glial cells in the central sensitization associated with OA, which may provide a novel analgesic target for the treatment of OA pain.
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Affiliation(s)
- Devi Rani Sagar
- Arthritis Research UK, Pain Centre, University of Nottingham, Nottingham, UK
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Paintlia AS, Paintlia MK, Singh AK, Orak JK, Singh I. Activation of PPAR-γ and PTEN cascade participates in lovastatin-mediated accelerated differentiation of oligodendrocyte progenitor cells. Glia 2011; 58:1669-85. [PMID: 20578043 DOI: 10.1002/glia.21039] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Previously, we and others documented that statins including-lovastatin (LOV) promote the differentiation of oligodendrocyte progenitor cells (OPCs) and remyelination in experimental autoimmune encephalomyelitis (EAE), an multiple sclerosis (MS) model. Conversely, some recent studies demonstrated that statins negatively influence oligodendrocyte (OL) differentiation in vitro and remyelination in a cuprizone-CNS demyelinating model. Therefore, herein, we first investigated the cause of impaired differentiation of OLs by statins in vitro settings. Our observations indicated that the depletion of cholesterol was detrimental to LOV treated OPCs under cholesterol/serum-deprived culture conditions similar to that were used in conflicting studies. However, the depletion of geranylgeranyl-pp under normal cholesterol homeostasis conditions enhanced the phenotypic commitment and differentiation of LOV-treated OPCs ascribed to inhibition of RhoA-Rho kinase. Interestingly, this effect of LOV was associated with increased activation and expression of both PPAR-γ and PTEN in OPCs as confirmed by various pharmacological and molecular based approaches. Furthermore, PTEN was involved in an inhibition of OPCs proliferation via PI3K-Akt inhibition and induction of cell cycle arrest at G1 phase, but without affecting their cell survival. These effects of LOV on OPCs in vitro were absent in the CNS of normal rats chronically treated with LOV concentrations used in EAE indicating that PPAR-γ induction in normal brain may be tightly regulated-providing evidences that statins are therapeutically safe for humans. Collectively, these data provide initial evidence that statin-mediated activation of the PPAR-γ-PTEN cascade participates in OL differentiation, thus suggesting new therapeutic-interventions for MS or related CNS-demyelinating diseases.
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Affiliation(s)
- Ajaib S Paintlia
- Department of Pediatrics, Darby Children's Research Institute, Medical University of South Carolina, South Carolina, USA
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Pham H, Vincenti R, Slice LW. COX-2 promoter activation by AT1R-Gq-PAK-p38β signaling in intestinal epithelial cells. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2008; 1779:408-13. [DOI: 10.1016/j.bbagrm.2008.05.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 04/04/2008] [Accepted: 05/06/2008] [Indexed: 11/16/2022]
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Routtenberg A. The substrate for long-lasting memory: if not protein synthesis, then what? Neurobiol Learn Mem 2007; 89:225-33. [PMID: 18162421 DOI: 10.1016/j.nlm.2007.10.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 10/29/2007] [Accepted: 10/29/2007] [Indexed: 01/20/2023]
Abstract
The prevailing textbook view that de novo protein synthesis is required for memory (e.g., [Bear, M. F., Connors, B., & Paradiso, M. 2006. Neuroscience. Lippincott, New York]) is seriously flawed and an alternative hypothesis has been proposed in which post-translational modification (PTM) of proteins already synthesized and already present within the synapse is 'the' substrate for long-lasting memory. Protein synthesis serves a replenishment role. The first part of this review discusses how long-lasting memory can be achieved with 'only' PTM of existing synaptic proteins. The second part critically reviews a recent report published in Neuron 2007 that exemplifies the current view of protein synthesis and memory while also illustrating how these results can be understood within this new PTM framework. A necessary yet unexpected conclusion to emerge from consideration of the consequences of a PTM mechanism as the necessary, sufficient and exclusive substrate for long-lasting memory, is that the central Hebbian dogma that cells that 'fire together, wire together' is an unlikely mechanism for long-lasting memory. Thus, a unique feature of the PTM model is that longevity of information storage is achieved not by stability of the synaptic mechanism, but by impermanent pseudoredundant circuits. This is so because PTM is a reversible process and thus any permanent connection, any 'lasting effect' cannot be in the form of stable synapse formation. We have therefore proposed a solution in which network level processes regulate cellular mechanisms, even as such mechanisms regulate the network. Thus, synapses are 'meta-stabilized' by regulated feedback mediated by the circuit in which the synapse is embedded. For example, spontaneous activity is proposed to be a substrate feedback mechanism we term 'cryptic rehearsal' to sustain for some period of time after learning an approximation to the state initially created by input. Additionally, because the duplication of these traces is ongoing, this provides a degenerate code for the engram. Stability is thus achieved, not by stabilizing the synapse, but by implementing a pseudo-redundant yet malleable circuitry so that memory can be protected in the face of small catastrophes in network representation.
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Affiliation(s)
- Aryeh Routtenberg
- Department of Psychology, Northwestern University, Evanston IL 60208, USA.
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Pham H, Chong B, Vincenti R, Slice LW. Ang II and EGF synergistically induce COX-2 expression via CREB in intestinal epithelial cells. J Cell Physiol 2007; 214:96-109. [PMID: 17559081 DOI: 10.1002/jcp.21167] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Cyclooxygenase (COX)-2 derived prostaglandins (PGs) play a major role in intestinal inflammation and colorectal carcinogenesis. Because COX-2 is the rate-limiting step in the production of PGs, mechanisms that regulate COX-2 expression control PG production in the cell. Using the non-tumorigenic, rat intestinal epithelial cell, IEC-18, we demonstrate that co-activation of endogenously expressed AT(1) receptor and EGFR resulted in synergistic expression of COX-2 mRNA and protein involving transcriptional and post-transcriptional mechanisms. Ang II and EGF induced transient phosphorylation of ERK, p38(MAPK) and CREB. Co-stimulation with Ang II and EGF prolonged phosphorylation of ERK, p38(MAPK), and CREB. The p38(MAPK) selective inhibitor, SB202190, but not the MEK selective inhibitor, PD98059, or the EGFR kinase inhibitor, AG1478, inhibited Ang II-dependent COX-2 expression and CREB phosphorylation. EGF-dependent COX-2 expression and CREB phosphorylation were inhibited by SB202190, PD98059, and AG1478. Inhibition of CREB expression using two separate RNAi methods blocked COX-2 expression by Ang II and EGF. Expression of a dominant negative CREB mutant inhibited Ang II- and EGF-dependent induction of the COX-2 promoter. Ang II induced luciferase expression in cells transfected with the CRE-luc reporter vector and cells co-transfected with Gal4-luc reporter vector and a Gal4-CREB expression vector. Chromatin immunoprecipitation assays demonstrated CREB binding to the proximal rat COX-2 promoter region containing a CRE cis-acting element. These results indicate that co-stimulation with Ang II and EGF synergistically induced COX-2 expression in these intestinal epithelial cells through p38(MAPK) mediated signaling cascades that converge onto CREB.
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Affiliation(s)
- Hung Pham
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095-1786, USA
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Li W, Venkataraman GM, Ain KB. Protein synthesis inhibitors, in synergy with 5-azacytidine, restore sodium/iodide symporter gene expression in human thyroid adenoma cell line, KAK-1, suggesting trans-active transcriptional repressor. J Clin Endocrinol Metab 2007; 92:1080-7. [PMID: 17164311 DOI: 10.1210/jc.2006-2106] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Therapy of thyroid carcinoma uses its radioiodine concentration ability for treatment. Dedifferentiated cells lose radioiodine uptake from human sodium-iodide symporter (hNIS) gene transcription failure consequent to genomic structure (chromatin compaction) and composition (CpG methylation). OBJECTIVE AND METHODS We explored restoring hNIS expression in human thyroid carcinoma cells using thyroid adenoma and carcinoma cell lines: KAK-1, NPA87, BHT-101, and KAT-4B, with quantitative RT-PCR, chromatin immunoprecipitation, deoxyribonuclease I sensitivity assays, and luciferase reporter construct transfections containing hNIS promoter regions. RESULTS Combined 5-azacytidine and sodium butyrate restores hNIS gene transcription in KAK-1 to levels approaching radioiodine-treatable tumors. Despite induction of H4 acetylation, there was no deoxyribonuclease I sensitivity enhancement in two regions of the hNIS gene promoter. Cycloheximide in cells transfected with luciferase reporter construct, 1.3 kb hNIS gene promoter, stimulated normalized luciferase expression, singly and synergistically with 5-azacytidine, in a dose-dependent, time course-dependent, cell type-specific, and promoter-specific fashion. Both anisomycin and emetine, but not puromycin, had similar effects. Cycloheximide also increased endogenous hNIS mRNA. Transfections with reporter constructs containing consecutive deletions of hNIS gene promoter sequences revealed responsible sequences at -427 to -131 bp. Deletion of 1.2 kb promoter region upstream of -131 bp enhanced basal luciferase reporter activity 3-fold above the activity of full length promoter construct, supporting inhibitory properties of this region. CONCLUSIONS This suggests that trans-active protein factor(s) represses endogenous hNIS transcription in KAK-1 cells under basal conditions, accounting for loss of iodine uptake. Inhibition of this repressive activity increases endogenous hNIS transcription and presents a novel target to restore hNIS expression in dedifferentiated thyroid carcinoma.
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Affiliation(s)
- Wei Li
- Thyroid Cancer Research Laboratory, Medical Service, Veterans Affairs Medical Center, Lexington, Kentucky 40511, USA
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Pham H, Shafer LM, Slice LW. CREB-dependent cyclooxygenase-2 and microsomal prostaglandin E synthase-1 expression is mediated by protein kinase C and calcium. J Cell Biochem 2006; 98:1653-66. [PMID: 16598755 DOI: 10.1002/jcb.20899] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cellular production of prostaglandins (PGs) is controlled by the concerted actions of cyclooxygenases (COX) and terminal PG synthases on arachidonic acid in response to agonist stimulation. Recently, we showed in an ileal epithelial cell line (IEC-18), angiotensin II-induced COX-2-dependent PGI2 production through p38MAPK, and calcium mobilization (J. Biol. Chem. 280: 1582-1593, 2005). Agonist binding to the AT1 receptor results in activation of PKC activity and Ca2+ signaling but it is unclear how each pathway contributes to PG production. IEC-18 cells were stimulated with either phorbol-12,13-dibutyrate (PDB), thapsigargin (TG), or in combination. The PG production and COX-2 and PG synthase expression were measured. Surprisingly, PDB and TG produced PGE2 but not PGI2. This corresponded to induction of COX-2 and mPGES-1 mRNA and protein. PGIS mRNA and protein levels did not change. Activation of PKC by PDB resulted in the activation of ERK1/2, JNK, and CREB whereas activation of Ca2+ signaling by TG resulted in the delayed activation of ERK1/2. The combined effect of PKC and Ca2+ signaling were prolonged COX-2 and mPGES-1 mRNA and protein expression. Inhibition of PKC activity, MEK activity, or Ca2+ signaling blocked agonist induction of COX-2 and mPGES-1. Expression of a dominant negative CREB (S133A) blocked PDB/TG-dependent induction of both COX-2 and mPGES-1 promoters. Decreased CREB expression by siRNA blocked PDB/TG-dependent expression of COX-2 and mPGES-1 mRNA. These findings demonstrate a coordinated induction of COX-2 and mPGES-1 by PDB/TG that proceeds through PKC/ERK and Ca2+ signaling cascades, resulting in increased PGE2 production.
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Affiliation(s)
- Hung Pham
- Department of Medicine, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, University of California, Los Angeles, California 90095-1786, USA
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Clarke CJ, Truong TG, Hannun YA. Role for neutral sphingomyelinase-2 in tumor necrosis factor alpha-stimulated expression of vascular cell adhesion molecule-1 (VCAM) and intercellular adhesion molecule-1 (ICAM) in lung epithelial cells: p38 MAPK is an upstream regulator of nSMase2. J Biol Chem 2006; 282:1384-96. [PMID: 17085432 DOI: 10.1074/jbc.m609216200] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Neutral sphingomyelinases (N-SMases) are major candidates for stress-induced ceramide production. However, there is little information on the physiological regulation and roles of the cloned N-SMase enzyme, nSMase2. In this study, nSMase2 was found to translocate acutely to the plasma membrane of A549 epithelial cells in response to tumor necrosis factor alpha (TNF-alpha) in a time- and dose-dependent manner. Additionally, TNF-alpha increased N-SMase activity rapidly and transiently both endogenously and in cells overexpressing nSMase2. Furthermore, the translocation of nSMase2 was regulated by p38-alpha MAPK, but not ERK or JNK, and the increase in endogenous N-SMase activity was abrogated by p38 MAPK inhibition. In addition, both p38-alpha MAPK and nSMase2 were implicated in the TNF-alpha-stimulated up-regulation of the adhesion proteins vascular cell adhesion molecule-1 (VCAM) and intercellular adhesion molecule-1 (ICAM), but this was largely independent of NF-kappaB activation. These data reveal p38 MAPK as an upstream regulator of nSMase2 and indicate a role for nSMase2 in pro-inflammatory responses induced by TNF-alpha as a regulator of adhesion proteins.
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Affiliation(s)
- Christopher J Clarke
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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