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Zhou L, Fang L, Tamm M, Stolz D, Roth M. Extracellular Heat Shock Protein 70 Increases the Glucocorticoid Receptor and Dual-Specificity Phosphatase 1 via Toll-like Receptor 4 and Attenuates Inflammation in Airway Epithelial Cells. Int J Mol Sci 2023; 24:11700. [PMID: 37511459 PMCID: PMC10380817 DOI: 10.3390/ijms241411700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/07/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
Heat shock protein 70 (HSP70) regulates the ligand binding of the glucocorticoid receptor (GR). In asthma patients, heat treatment increased both the GR expression and secretion of extracellular HSP70 (eHSP70) by bronchial epithelial cells (EC). The objective of this study was to assess the effects of eHSP70 on GR expression and the GR-dependent regulation of immune response in human bronchial ECs. Cells were treated with either eHSP70 or transfected with an expression vector for intracellular HSP70 (iHSP70). Ribonucleic acid (RNA) and protein levels were detected by reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting, and immunofluorescence. Interleukin (IL-6 and IL-8) secretion was determined by enzyme linked immunosorbent assay (ELISA). The overexpression of iHSP70 decreased, while eHSP70 increased GR expression. In addition, eHSP70 increased the expression of the GR target dual-specificity phosphatase 1 (DUSP-1). In doing so, eHSP70 reduced the tumor growth factor (TGF)-β1-dependent activation of extracellular signal-regulated kinase (Erk)-1/2 and cyclic AMP response element binding protein (CREB) and the secretion of IL-6 and IL-8. Blocking the GR or Toll-like receptor 4 (TLR4) counteracted all eHSP70-induced effects. This study demonstrates a novel anti-inflammatory effect of eHSP70 by the signaling cascade of TLR4-GR-DUSP1, which inhibits TGF-β1-activated pro-inflammatory ERK1/2-CREB signaling and cytokine secretion. The findings suggest that eHSP70 might present a novel non-steroidal therapeutic strategy to control airway inflammation in asthma.
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Affiliation(s)
- Liang Zhou
- Pulmonary Cell Research, Department Biomedicine & Clinic of Pneumology, University & University Hospital of Basel, 4031 Basel, Switzerland
| | - Lei Fang
- Pulmonary Cell Research, Department Biomedicine & Clinic of Pneumology, University & University Hospital of Basel, 4031 Basel, Switzerland
| | - Michael Tamm
- Pulmonary Cell Research, Department Biomedicine & Clinic of Pneumology, University & University Hospital of Basel, 4031 Basel, Switzerland
- Clinic of Pneumology and Pulmonary Cell Research, University Hospital of Basel, 4031 Basel, Switzerland
| | - Daiana Stolz
- Clinic of Pneumology and Pulmonary Cell Research, University Hospital of Basel, 4031 Basel, Switzerland
| | - Michael Roth
- Pulmonary Cell Research, Department Biomedicine & Clinic of Pneumology, University & University Hospital of Basel, 4031 Basel, Switzerland
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Feng J, Meng W, Chen L, Zhang X, Markazi A, Yuan W, Huang Y, Gao SJ. N(6)-Methyladenosine and Reader Protein YTHDF2 Enhance the Innate Immune Response by Mediating DUSP1 mRNA Degradation and Activating Mitogen-Activated Protein Kinases during Bacterial and Viral Infections. mBio 2023; 14:e0334922. [PMID: 36625590 DOI: 10.1128/mbio.03349-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Mitogen-activated protein kinases (MAPKs) play critical roles in the induction of numerous cytokines, chemokines, and inflammatory mediators that mobilize the immune system to counter pathogenic infections. Dual-specificity phosphatase 1 (DUSP1) is a member of the dual-specificity phosphatases that inactivates MAPKs through a negative-feedback mechanism. Here, we report that in response to viral and bacterial infections, not only the DUSP1 transcript but also its N6-methyladenosine (m6A) levels rapidly increase together with that of the m6A reader protein YTHDF2, resulting in enhanced YTHDF2-mediated DUSP1 transcript degradation. The knockdown of DUSP1 promotes p38 and Jun N-terminal kinase (JNK) phosphorylation and activation, thus increasing the expression of innate immune response genes, including the interleukin-1β (IL-1β), colony-stimulating factor 3 (CSF3), transglutaminase 2 (TGM2), and proto-oncogene tyrosine-protein kinase Src (SRC) genes. Similarly, the knockdown of the m6A eraser ALKBH5 increases the DUSP1 transcript m6A level, resulting in accelerated transcript degradation, the activation of p38 and JNK, and the enhanced expression of IL-1β, CSF3, TGM2, and SRC. These results demonstrate that m6A and the reader protein YTHDF2 orchestrate optimal innate immune responses during viral and bacterial infections by downregulating the expression of a negative regulator, DUSP1, of the p38 and JNK pathways that are central to innate immune responses against pathogenic infections. IMPORTANCE Innate immunity is central to controlling pathogenic infections and maintaining the homeostasis of the host. In this study, we have revealed a novel mechanism regulating innate immune responses during viral and bacterial infections. We have found that N6-methyladenosine (m6A) and the reader protein YTHDF2 regulate dual-specificity phosphatase 1, a negative regulator of the mitogen-activated protein kinases p38 and JNK, to maximize innate immune responses during viral and bacterial infections. These results provide novel insights into the mechanism regulating innate immunity, which could help in the development of novel approaches for controlling pathogenic infections.
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Chen WR, Huo X, Zhou YJ, Chen YD, Ma Q, Jin QH, Wu XP, Sha Y. [ Dual-specificity Phosphatase 1 Suppresses Vascular Smooth Muscle Cell Calcification by Optical Atrophy 1-related Pathway]. Zhongguo Yi Xue Ke Xue Yuan Xue Bao 2022; 44:377-383. [PMID: 35791932 DOI: 10.3881/j.issn.1000-503x.14421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Objective To investigate the effect of dual-specificity phosphatase 1/optical atrophy 1 (DUSP1/OPA1) signaling pathway on vascular smooth muscle cell (VSMC) calcification.Methods An in vitro model of VSMC calcification was induced by exposure to β-glycerophosphate and calcium chloride.VSMC calcification was assessed by Alizarin Red S staining and calcium content by ELISA.Apoptosis was detected by TUNEL.Western blotting was employed to determine the protein levels of DUSP1,OPA1,Runt-related transcription factor 2 (Runx-2),bone morphogenetic protein 2 (BMP-2),and cysteinyl aspartate-specific proteinase-3 (Caspase-3).The effects of DUSP1 overexpression and OPA1 knockdown on cell calcification were investigated.Results Calcium chloride and β-glycerolphosphate induced VSMC calcification and down-regulated the expression levels of DUSP1 (t=11.951,P<0.001) and OPA1 (t=8.487,P<0.001).DUSP1 overexpression promoted OPA1 expression (t=-8.921,P<0.001),attenuated VSMC calcification,reduced calcium content and apoptosis rate,and down-regulated the expression of Runx-2,BMP-2,and active Caspase-3 (all P<0.001).OPA1 knockdown increased calcium content and apoptosis rate,up-regulated the expression of Runx-2,BMP-2,and active Caspase-3,and promoted VSMC calcification (all P<0.001).Conclusion DUSP1 may inhibit the VSMC calcification through the OPA1 signaling pathway.
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Affiliation(s)
- Wei-Ren Chen
- Department of Cardiology,Beijing Institute of Heart Lung and Blood Vessel Diseases,Beijing Key Laboratory of Precision Medicine of Coronary Atherosclerotic Disease,Clinical Center for Coronary Heart Disease of Capital Medical University,Beijing Anzhen Hospital,Capital Medical University,Beijing 100029,China
- Department of Cardiology,National Clinical Research Center for Geriatric Diseases,the Second Medical Center of Chinese PLA General Hospital,Beijing 100853,China
| | - Xia Huo
- Department of Cardiology,National Clinical Research Center for Geriatric Diseases,the Second Medical Center of Chinese PLA General Hospital,Beijing 100853,China
| | - Yu-Jie Zhou
- Department of Cardiology,Beijing Institute of Heart Lung and Blood Vessel Diseases,Beijing Key Laboratory of Precision Medicine of Coronary Atherosclerotic Disease,Clinical Center for Coronary Heart Disease of Capital Medical University,Beijing Anzhen Hospital,Capital Medical University,Beijing 100029,China
| | - Yun-Dai Chen
- Department of Cardiology,the First Medical Center of Chinese PLA General Hospital,Beijing 100853,China
| | - Qian Ma
- Department of Cardiology,Beijing Institute of Heart Lung and Blood Vessel Diseases,Beijing Key Laboratory of Precision Medicine of Coronary Atherosclerotic Disease,Clinical Center for Coronary Heart Disease of Capital Medical University,Beijing Anzhen Hospital,Capital Medical University,Beijing 100029,China
| | - Qin-Hua Jin
- Department of Cardiology,the First Medical Center of Chinese PLA General Hospital,Beijing 100853,China
| | - Xue-Ping Wu
- Department of Cardiology,National Clinical Research Center for Geriatric Diseases,the Second Medical Center of Chinese PLA General Hospital,Beijing 100853,China
| | - Yuan Sha
- Department of Cardiology,National Clinical Research Center for Geriatric Diseases,the Second Medical Center of Chinese PLA General Hospital,Beijing 100853,China
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Gumpena R, Lountos GT, Waugh DS. MBP-binding DARPins facilitate the crystallization of an MBP fusion protein. Acta Crystallogr F Struct Biol Commun 2018; 74:549-557. [PMID: 30198887 PMCID: PMC6130421 DOI: 10.1107/s2053230x18009901] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 07/10/2018] [Indexed: 12/02/2022]
Abstract
Designed ankyrin-repeat proteins (DARPins) that bind to maltose-binding protein (MBP) with high affinity can facilitate the crystallization of an MBP fusion protein. The use of MBP-specific DARPins increases the probability of obtaining crystals. The production of high-quality crystals is the main bottleneck in determining the structures of proteins using X-ray crystallography. In addition to being recognized as a very effective solubility-enhancing fusion partner, Escherichia coli maltose-binding protein (MBP) has also been successfully employed as a ‘fixed-arm’ crystallization chaperone in more than 100 cases. Here, it is reported that designed ankyrin-repeat proteins (DARPins) that bind with high affinity to MBP can promote the crystallization of an MBP fusion protein when the fusion protein alone fails to produce diffraction-quality crystals. As a proof of principle, three different co-crystal structures of MBP fused to the catalytic domain of human dual-specificity phosphatase 1 in complex with DARPins are reported.
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Affiliation(s)
- Rajesh Gumpena
- Macromolecular Crystallography Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - George T Lountos
- Macromolecular Crystallography Laboratory, Basic Science Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research Sponsored by the National Cancer Institute, Frederick, MD 21702, USA
| | - David S Waugh
- Macromolecular Crystallography Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
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Fang J, Ye Z, Gu F, Yan M, Lin Q, Lin J, Wang Z, Xu Y, Wang Y. DUSP1 enhances the chemoresistance of gallbladder cancer via the modulation of the p38 pathway and DNA damage/repair system. Oncol Lett 2018; 16:1869-1875. [PMID: 30008878 DOI: 10.3892/ol.2018.8822] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 11/21/2017] [Indexed: 01/03/2023] Open
Abstract
Cisplatin (CDDP) is a commonly used drug for gallbladder cancer (GBC) chemotherapy. However, resistance to CDDP treatment results in relapse. Therefore, there is a need for the development of more effective treatment strategies to overcome chemoresistance. Dual-specificity phosphatase 1 (DUSP1) was reported to be involved in the resistance of a number of chemotherapeutic agents and was revealed to be highly expressed in CDDP-resistant GBC cells and CDDP-treated tumor types compared with normal cells or tissues in the present study. DUSP1 was revealed to inhibit the cytotoxicity of CDDP in two GBC cell lines, SGC996 and GBC-SD. P38 mitogen-activated protein kinases may be involved in the mechanism of chemoresistance. Furthermore, the number of DNA double-strand breaks in SGC996 OE cells was reduced compared with SGC996 vector cells indicating DUSP1 may attenuate the chemotherapeutic efficiency. Due to its potency against CDDP treatment, DUSP1 may be a promising target to overcome chemoresistance in GBC therapy.
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Affiliation(s)
- Jun Fang
- Department of Radiation Oncology, Zhejiang Province Cancer Hospital, Hangzhou, Zhejiang 310022, P.R. China
| | - Zhimin Ye
- Department of Radiation Oncology, Zhejiang Province Cancer Hospital, Hangzhou, Zhejiang 310022, P.R. China
| | - Feiying Gu
- Department of Radiation Oncology, Zhejiang Province Cancer Hospital, Hangzhou, Zhejiang 310022, P.R. China
| | - Maohui Yan
- Department of Radiation Oncology, Zhejiang Province Cancer Hospital, Hangzhou, Zhejiang 310022, P.R. China
| | - Qingren Lin
- Department of Radiation Oncology, Zhejiang Province Cancer Hospital, Hangzhou, Zhejiang 310022, P.R. China
| | - Juan Lin
- Department of Radiation Oncology, Zhejiang Province Cancer Hospital, Hangzhou, Zhejiang 310022, P.R. China
| | - Zhun Wang
- Department of Radiation Oncology, Zhejiang Province Cancer Hospital, Hangzhou, Zhejiang 310022, P.R. China
| | - Yaping Xu
- Department of Radiation Oncology, Zhejiang Province Cancer Hospital, Hangzhou, Zhejiang 310022, P.R. China
| | - Yuezhen Wang
- Department of Radiation Oncology, Zhejiang Province Cancer Hospital, Hangzhou, Zhejiang 310022, P.R. China
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O'Neil JD, Ross EA, Ridley ML, Ding Q, Tang T, Rosner DR, Crowley T, Malhi D, Dean JL, Smallie T, Buckley CD, Clark AR. Gain-of-Function Mutation of Tristetraprolin Impairs Negative Feedback Control of Macrophages In Vitro yet Has Overwhelmingly Anti-Inflammatory Consequences In Vivo. Mol Cell Biol 2017; 37:e00536-16. [PMID: 28265004 DOI: 10.1128/MCB.00536-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 02/25/2017] [Indexed: 12/20/2022] Open
Abstract
The mRNA-destabilizing factor tristetraprolin (TTP) binds in a sequence-specific manner to the 3' untranslated regions of many proinflammatory mRNAs and recruits complexes of nucleases to promote rapid mRNA turnover. Mice lacking TTP develop a severe, spontaneous inflammatory syndrome characterized by the overexpression of tumor necrosis factor and other inflammatory mediators. However, TTP also employs the same mechanism to inhibit the expression of the potent anti-inflammatory cytokine interleukin 10 (IL-10). Perturbation of TTP function may therefore have mixed effects on inflammatory responses, either increasing or decreasing the expression of proinflammatory factors via direct or indirect mechanisms. We recently described a knock-in mouse strain in which the substitution of 2 amino acids of the endogenous TTP protein renders it constitutively active as an mRNA-destabilizing factor. Here we investigate the impact on the IL-10-mediated anti-inflammatory response. It is shown that the gain-of-function mutation of TTP impairs IL-10-mediated negative feedback control of macrophage function in vitro However, the in vivo effects of TTP mutation are uniformly anti-inflammatory despite the decreased expression of IL-10.
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Xiao J, Tang J, Chen Q, Tang D, Liu M, Luo M, Wang Y, Wang J, Zhao Z, Tang C, Wang D, Mo Z. miR-429 regulates alveolar macrophage inflammatory cytokine production and is involved in LPS-induced acute lung injury. Biochem J 2015; 471:281-91. [PMID: 26431850 DOI: 10.1042/BJ20131510] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 08/20/2015] [Indexed: 12/13/2022]
Abstract
p38 MAPK (mitogen-activated protein kinase) is a critical regulator in lung inflammation. It can be inactivated by DUSP1 (dual-specificity phosphatase 1) which was identified as a putative target of miR-429. miR-429 mimics directly targeted to the 3'-UTR of the gene encoding DUSP1 may result in the translational attenuation of DUSP1. Moreover, the phosphorylation of p38 MAPK was prolonged after miR-429 mimic treatment. Additionally, miR-429 expression was sensitive to LPS (lipopolysaccharide) stimulation and the miR-429 mimics increased the production of pro-inflammatory cytokines. However, anti-miR-429 reduced the LPS-induced production of pro-inflammatory cytokines. These results provide direct evidence that miR-429 is involved in the LPS-induced inflammatory response. In parallel with miR-429, miR-200b and miR-200c, but not miR-200a or miR-141, shared similar effects. In vivo, LPS induced the expression of miR-429, miR-200b and miR-200c in lung. At the same time, inhibiting these miRNAs by anti-miRNAs attenuated the LPS-induced pulmonary inflammatory response and injury. These findings reveal that miR-429 possesses pro-inflammatory activities and may be a potential therapy target for LPS-induced lung injury.
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Khadir A, Tiss A, Abubaker J, Abu-Farha M, Al-Khairi I, Cherian P, John J, Kavalakatt S, Warsame S, Al-Madhoun A, Al-Ghimlas F, Elkum N, Behbehani K, Dermime S, Dehbi M. MAP kinase phosphatase DUSP1 is overexpressed in obese humans and modulated by physical exercise. Am J Physiol Endocrinol Metab 2015; 308:E71-83. [PMID: 25370852 DOI: 10.1152/ajpendo.00577.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chronic low-grade inflammation and dysregulation of the stress defense system are cardinal features of obesity, a major risk factor for the development of insulin resistance and diabetes. Dual-specificity protein phosphatase 1 (DUSP1), known also as MAP kinase phosphatase 1 (MKP1), is implicated in metabolism and energy expenditure. Mice lacking DUSP1 are resistant to high-fat diet-induced obesity. However, the expression of DUSP1 has not been investigated in human obesity. In the current study, we compared the expression pattern of DUSP1 between lean and obese nondiabetic human subjects using subcutaneous adipose tissue (SAT) and peripheral blood mononuclear cells (PBMCs). The levels of DUSP1 mRNA and protein were significantly increased in obese subjects with concomitant decrease in the phosphorylation of p38 MAPK (p-p38 MAPK) and PGC-1α and an increase in the levels of phospho-JNK (p-JNK) and phospho-ERK (p-ERK). Moreover, obese subjects had higher levels of circulating DUSP1 protein that correlated positively with various obesity indicators, triglycerides, glucagon, insulin, leptin, and PAI-1 (P < 0.05) but negatively with V̇O(2max) and high-density lipoprotein (P < 0.05). The observation that DUSP1 was overexpressed in obese subjects prompted us to investigate whether physical exercise could reduce its expression. In this study, we report for the first time that physical exercise significantly attenuated the expression of DUSP1 in both the SAT and PBMCs, with a parallel increase in the expression of PGC-1α and a reduction in the levels of p-JNK and p-ERK along with attenuated inflammatory response. Collectively, our data suggest that DUSP1 upregulation is strongly linked to adiposity and that physical exercise modulates its expression. This gives further evidence that exercise might be useful as a strategy for managing obesity and preventing its associated complications.
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Affiliation(s)
| | - Ali Tiss
- Deptartment of Biomedical Research
| | | | | | | | | | | | | | | | | | | | - Naser Elkum
- Department of Biostatistics and Epidemiology, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Kazem Behbehani
- Deptartment of Biomedical Research, Fitness and Rehabilitation Center, and Department of Biostatistics and Epidemiology, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Said Dermime
- King Fahad Specialist Hospital, Dammam, Saudi Arabia; and
| | - Mohammed Dehbi
- Diabetes Research Centre, Qatar Biomedical Research Institute, Qatar Foundation, Doha, Qatar
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Ratman D, Vanden Berghe W, Dejager L, Libert C, Tavernier J, Beck IM, De Bosscher K. How glucocorticoid receptors modulate the activity of other transcription factors: a scope beyond tethering. Mol Cell Endocrinol 2013; 380:41-54. [PMID: 23267834 DOI: 10.1016/j.mce.2012.12.014] [Citation(s) in RCA: 273] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 12/13/2012] [Accepted: 12/16/2012] [Indexed: 01/11/2023]
Abstract
The activity of the glucocorticoid receptor (GR), a nuclear receptor transcription factor belonging to subclass 3C of the steroid/thyroid hormone receptor superfamily, is typically triggered by glucocorticoid hormones. Apart from driving gene transcription via binding onto glucocorticoid response elements in regulatory regions of particular target genes, GR can also inhibit gene expression via transrepression, a mechanism largely based on protein:protein interactions. Hereby GR can influence the activity of other transcription factors, without contacting DNA itself. GR is known to inhibit the activity of a growing list of immune-regulating transcription factors. Hence, GCs still rule the clinic for treatments of inflammatory disorders, notwithstanding concomitant deleterious side effects. Although patience is a virtue when it comes to deciphering the many mechanisms GR uses to influence various signaling pathways, the current review is testimony of the fact that groundbreaking mechanistic work has been accumulating over the past years and steadily continues to grow.
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Affiliation(s)
- Dariusz Ratman
- Cytokine Receptor Lab, VIB Department of Medical Protein Research, VIB, UGent, Albert Baertsoenkaai 3, B-9000 Gent, Belgium.
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Frau M, Feo F, Pascale RM. Pleiotropic effects of methionine adenosyltransferases deregulation as determinants of liver cancer progression and prognosis. J Hepatol 2013; 59:830-41. [PMID: 23665184 DOI: 10.1016/j.jhep.2013.04.031] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 04/15/2013] [Accepted: 04/23/2013] [Indexed: 12/13/2022]
Abstract
Downregulation of liver-specific MAT1A gene, encoding S-adenosylmethionine (SAM) synthesizing isozymes MATI/III, and upregulation of widely expressed MAT2A, encoding MATII isozyme, known as MAT1A:MAT2A switch, occurs in hepatocellular carcinoma (HCC). Being inhibited by its reaction product, MATII isoform upregulation cannot compensate for MATI/III decrease. Therefore, MAT1A:MAT2A switch contributes to decrease in SAM level in rodent and human hepatocarcinogenesis. SAM administration to carcinogen-treated rats prevents hepatocarcinogenesis, whereas MAT1A-KO mice, characterized by chronic SAM deficiency, exhibit macrovesicular steatosis, mononuclear cell infiltration in periportal areas, and HCC development. This review focuses upon the pleiotropic changes, induced by MAT1A/MAT2A switch, associated with HCC development. Epigenetic control of MATs expression occurs at transcriptional and post-transcriptional levels. In HCC cells, MAT1A/MAT2A switch is associated with global DNA hypomethylation, decrease in DNA repair, genomic instability, and signaling deregulation including c-MYC overexpression, rise in polyamine synthesis, upregulation of RAS/ERK, IKK/NF-kB, PI3K/AKT, and LKB1/AMPK axis. Furthermore, decrease in MAT1A expression and SAM levels results in increased HCC cell proliferation, cell survival, and microvascularization. All of these changes are reversed by SAM treatment in vivo or forced MAT1A overexpression or MAT2A inhibition in cultured HCC cells. In human HCC, MAT1A:MAT2A and MATI/III:MATII ratios correlate negatively with cell proliferation and genomic instability, and positively with apoptosis and global DNA methylation. This suggests that SAM decrease and MATs deregulation represent potential therapeutic targets for HCC. Finally, MATI/III:MATII ratio strongly predicts patients' survival length suggesting that MAT1A:MAT2A expression ratio is a putative prognostic marker for human HCC.
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Affiliation(s)
- Maddalena Frau
- Department of Clinical and Experimental Medicine, Laboratory of Experimental Pathology and Oncology, University of Sassari, Sassari, Italy
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