1
|
Nasl-Khameneh AM, Mirshafiey A, Moghadasi AN, Yekaninejad MS, Parastouei K, Nejati S, Saboor-Yaraghi AA. The immunomodulatory effects of all-trans retinoic acid and docosahexaenoic acid combination treatment on the expression of IL-2, IL-4, T-bet, and GATA3 genes in PBMCs of multiple sclerosis patients. Neurol Res 2023; 45:510-519. [PMID: 36598970 DOI: 10.1080/01616412.2022.2162222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
OBJECTIVES Multiple sclerosis (MS) is a potentially disabling autoimmune disease of the central nervous system. Neither the pathogenesis nor the effectiveness of treatment of MS has been fully understood. This in vitro trial evaluated the beneficial immunomodulatory effects of single and combined treatments of all-trans retinoic acid (ATRA) and docosahexaenoic acid (DHA) on the peripheral blood mononuclear cells (PBMCs) of relapsing-remitting MS (RRMS) patients who were receiving interferon beta (IFN-β). METHODS The PBMCs of 15 RRMS patients were isolated, cultured, and treated with single and combined treatments of ATRA and DHA. The expressions of IL-2, IL-4, T-bet, and GATA3 genes were evaluated using real-time PCR. RESULTS The results showed that a single treatment of ATRA could significantly suppress the gene expression of the pro-inflammatory cytokine, IL-2 (P < 0.05), and related transcription factor, T-bet (P < 0.001). The gene expression level of the anti-inflammatory cytokine, IL-4, and its transcription factor, GATA3, were not significantly changed. The expression of IL-2 and T-bet genes was significantly decreased in combination treatments of ATRA and DHA (P < 0.001). Significant suppression of IL-2 and T-bet (P < 0.001) was observed in ATRA and DHA combination therapy with half doses of their single treatment, which suggested a synergistic effect of these components. DISCUSSION Co-administration of vitamin A and DHA, an omega-3 fatty acid derivative, may exert a synergistic effect in modulating the immune system in MS patients; however, more studies are needed to evaluate the exact effects and mechanism of their actions on the immune cells.
Collapse
Affiliation(s)
- Ateke Mousavi Nasl-Khameneh
- Department of Cellular and Molecular Nutrition, School of Nutritional Sciences and Dietetics, International Campus, Tehran University of Medical Sciences, Tehran, Iran
| | - Abbas Mirshafiey
- Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Abdorreza Naser Moghadasi
- Department of Neurology and MS Research Center, Neuroscience Institute, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Mir Saeed Yekaninejad
- Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Karim Parastouei
- Department of Cellular and Molecular Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran
| | - Shima Nejati
- Department of Immunology, School of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Ali Akbar Saboor-Yaraghi
- Department of Cellular and Molecular Nutrition, School of Nutritional Sciences and Dietetics, International Campus, Tehran University of Medical Sciences, Tehran, Iran.,Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| |
Collapse
|
2
|
Phosphorylation of RXRα mediates the effect of JNK to suppress hepatic FGF21 expression and promote metabolic syndrome. Proc Natl Acad Sci U S A 2022; 119:e2210434119. [PMID: 36282921 PMCID: PMC9636906 DOI: 10.1073/pnas.2210434119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cJun NH2-terminal kinase (JNK) signaling pathway in the liver promotes systemic changes in metabolism by regulating peroxisome proliferator-activated receptor α (PPARα)-dependent expression of the hepatokine fibroblast growth factor 21 (FGF21). Hepatocyte-specific gene ablation studies demonstrated that the Mapk9 gene (encoding JNK2) plays a key mechanistic role. Mutually exclusive inclusion of exons 7a and 7b yields expression of the isoforms JNK2α and JNK2β. Here we demonstrate that Fgf21 gene expression and metabolic regulation are primarily regulated by the JNK2α isoform. To identify relevant substrates of JNK2α, we performed a quantitative phosphoproteomic study of livers isolated from control mice, mice with JNK deficiency in hepatocytes, and mice that express only JNK2α or JNK2β in hepatocytes. We identified the JNK substrate retinoid X receptor α (RXRα) as a protein that exhibited JNK2α-promoted phosphorylation in vivo. RXRα functions as a heterodimeric partner of PPARα and may therefore mediate the effects of JNK2α signaling on Fgf21 expression. To test this hypothesis, we established mice with hepatocyte-specific expression of wild-type or mutated RXRα proteins. We found that the RXRα phosphorylation site Ser260 was required for suppression of Fgf21 gene expression. Collectively, these data establish a JNK-mediated signaling pathway that regulates hepatic Fgf21 expression.
Collapse
|
3
|
Khalique A, Mohammed AK, Al-khadran NM, Gharaibeh MA, Abu-Gharbieh E, El-Huneidi W, Sulaiman N, Taneera J. Reduced Retinoic Acid Receptor Beta (Rarβ) Affects Pancreatic β-Cell Physiology. BIOLOGY 2022; 11:biology11071072. [PMID: 36101450 PMCID: PMC9312298 DOI: 10.3390/biology11071072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/15/2022] [Accepted: 07/15/2022] [Indexed: 12/02/2022]
Abstract
Various studies have suggested a link between vitamin A (VA), all-trans-retinol, and type 2 diabetes (T2D). However, the functional role/expression of vitamin A receptors (Rarα, β, and γ) in pancreatic β-cells is not clear yet. Accordingly, we performed a series of bioinformatics, molecular and functional experiments in human islet and INS-1 cells to evaluate the role of Rarβ on insulin secretion and pancreatic β-cell function. Microarray and RNA-sequencing (RAN-seq) expression analysis showed that RARα, β, and γ are expressed in human pancreatic islets. RNA-seq expression of RARβ in diabetic/hyperglycemic human islets (HbA1c ≥ 6.3%) revealed a significant reduction (p = 0.004) compared to nondiabetic/normoglycemic cells (HbA1c < 6%). The expression of RARβ with INS and PDX1 showed inverse association, while positive correlations were observed with INSR and HbA1c levels. Exploration of the T2D knowledge portal (T2DKP) revealed that several genetic variants in RARβ are associated with BMI. The most associated variant is rs6804842 (p = 1.2 × 10−25). Silencing of Rarβ in INS-1 cells impaired insulin secretion without affecting cell viability or apoptosis. Interestingly, reactive oxygen species (ROS) production levels were elevated and glucose uptake was reduced in Rarβ-silenced cells. mRNA expression of Ins1, Pdx1, NeuroD1, Mafa, Snap25, Vamp2, and Gck were significantly (p < 0.05) downregulated in Rarβ-silenced cells. For protein levels, Pro/Insulin, PDX1, GLUT2, GCK, pAKT/AKT, and INSR expression were downregulated considerably (p < 0.05). The expression of NEUROD and VAMP2 were not affected. In conclusion, our results indicate that Rarβ is an important molecule for β-cell function. Hence, our data further support the potential role of VA receptors in the development of T2D.
Collapse
Affiliation(s)
- Anila Khalique
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
| | - Abdul Khader Mohammed
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
| | - Nujood Mohammed Al-khadran
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
| | - Mutaz Al Gharaibeh
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
| | - Eman Abu-Gharbieh
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Waseem El-Huneidi
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
| | - Nabil Sulaiman
- Department of Family Medicine, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
| | - Jalal Taneera
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
- Correspondence: ; Tel.: +97-165-057-743
| |
Collapse
|
4
|
RXR – centralny regulator wielu ścieżek sygnałowych w organizmie. POSTEP HIG MED DOSW 2021. [DOI: 10.2478/ahem-2021-0005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Abstrakt
Receptory jądrowe (NRs) tworzą największą nadrodzinę czynników transkrypcyjnych, które odgrywają ważną rolę w regulacji wielu procesów biologicznych. Receptor kwasu 9-cis-retinowego (RXR) wydaje się odgrywać szczególną rolę wśród tej grupy białek, a to ma związek z jego zdolnością do tworzenia dimerów z innymi NRs. Ze względu na kontrolę ekspresji wielu genów, RXR stanowi bardzo dobry cel licznych terapii. Nieprawidłowości w szlakach modulowanych przez RXR są powiązane m.in. z chorobami neurodegeneracyjnymi, otyłością, cukrzycą, a także nowotworami. Istnieje wiele związków mogących regulować aktywność transkrypcyjną RXR. Jednak obecnie dopuszczonych do użytku klinicznego jest tylko kilka z nich. Retinoidy normalizują wzrost i różnicowanie komórek skóry i błon śluzowych, ponadto działają immunomodulująco oraz przeciwzapalnie. Stąd są stosowane przede wszystkim w chorobach skóry i w terapii niektórych chorób nowotworowych. W artykule przedstawiono ogólne wiadomości na temat RXR, jego budowy, ligandów i mechanizmu działania oraz potencjalnej roli w terapii nowotworów i zespołu metabolicznego.
Collapse
|
5
|
Chen G. The Interactions of Insulin and Vitamin A Signaling Systems for the Regulation of Hepatic Glucose and Lipid Metabolism. Cells 2021; 10:2160. [PMID: 34440929 PMCID: PMC8393264 DOI: 10.3390/cells10082160] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/17/2021] [Accepted: 08/19/2021] [Indexed: 02/07/2023] Open
Abstract
The pandemics of obesity and type 2 diabetes have become a concern of public health. Nutrition plays a key role in these concerns. Insulin as an anabolic hormonal was discovered exactly 100 years ago due to its activity in controlling blood glucose level. Vitamin A (VA), a lipophilic micronutrient, has been shown to regulate glucose and fat metabolism. VA's physiological roles are mainly mediated by its metabolite, retinoic acid (RA), which activates retinoic acid receptors (RARs) and retinoid X receptors (RXRs), which are two transcription factors. The VA status and activations of RARs and RXRs by RA and synthetic agonists have shown to affect the glucose and lipid metabolism in animal models. Both insulin and RA signaling systems regulate the expression levels of genes involved in the regulation of hepatic glucose and lipid metabolism. Interactions of insulin and RA signaling systems have been observed. This review is aimed at summarizing the history of diabetes, insulin and VA signaling systems; the effects of VA status and activation of RARs and RXRs on metabolism and RAR and RXR phosphorylation; and possible interactions of insulin and RA in the regulation of hepatic genes for glucose and lipid metabolism. In addition, some future research perspectives for understanding of nutrient and hormone interactions are provided.
Collapse
Affiliation(s)
- Guoxun Chen
- Department of Nutrition, University of Tennessee at Knoxville, Knoxville, TN 37996, USA
| |
Collapse
|
6
|
Yang N, Parker LE, Yu J, Jones JW, Liu T, Papanicolaou KN, Talbot CC, Margulies KB, O’Rourke B, Kane MA, Foster DB. Cardiac retinoic acid levels decline in heart failure. JCI Insight 2021; 6:137593. [PMID: 33724958 PMCID: PMC8119182 DOI: 10.1172/jci.insight.137593] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 03/10/2021] [Indexed: 12/17/2022] Open
Abstract
Although low circulating levels of the vitamin A metabolite, all-trans retinoic acid (ATRA), are associated with increased risk of cardiovascular events and all-cause mortality, few studies have addressed whether cardiac retinoid levels are altered in the failing heart. Here, we showed that proteomic analyses of human and guinea pig heart failure (HF) were consistent with a decline in resident cardiac ATRA. Quantitation of the retinoids in ventricular myocardium by mass spectrometry revealed 32% and 39% ATRA decreases in guinea pig HF and in patients with idiopathic dilated cardiomyopathy (IDCM), respectively, despite ample reserves of cardiac vitamin A. ATRA (2 mg/kg/d) was sufficient to mitigate cardiac remodeling and prevent functional decline in guinea pig HF. Although cardiac ATRA declined in guinea pig HF and human IDCM, levels of certain retinoid metabolic enzymes diverged. Specifically, high expression of the ATRA-catabolizing enzyme, CYP26A1, in human IDCM could dampen prospects for an ATRA-based therapy. Pertinently, a pan-CYP26 inhibitor, talarozole, blunted the impact of phenylephrine on ATRA decline and hypertrophy in neonatal rat ventricular myocytes. Taken together, we submit that low cardiac ATRA attenuates the expression of critical ATRA-dependent gene programs in HF and that strategies to normalize ATRA metabolism, like CYP26 inhibition, may have therapeutic potential.
Collapse
Affiliation(s)
- Ni Yang
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Lauren E. Parker
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jianshi Yu
- Mass Spectrometry Center and Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland, USA
| | - Jace W. Jones
- Mass Spectrometry Center and Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland, USA
| | - Ting Liu
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - C. Conover Talbot
- Institute for Basic Biomedical Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Kenneth B. Margulies
- Penn Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Brian O’Rourke
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Maureen A. Kane
- Mass Spectrometry Center and Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland, USA
| | - D. Brian Foster
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| |
Collapse
|
7
|
Shao M, Lu L, Wang Q, Ma L, Tian X, Li C, Li C, Guo D, Wang Q, Wang W, Wang Y. The multi-faceted role of retinoid X receptor in cardiovascular diseases. Biomed Pharmacother 2021; 137:111264. [PMID: 33761589 DOI: 10.1016/j.biopha.2021.111264] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/04/2021] [Accepted: 01/07/2021] [Indexed: 01/14/2023] Open
Abstract
Retinoid X receptors (RXRs) are members of ligand-dependent transcription factors whose effects on a diversity of cellular processes, including cellular proliferation, the immune response, and lipid and glucose metabolism. Knock out of RXRα causes a hypoplasia of the myocardium which is lethal during fetal life. In addition, the heart maintains a well-orchestrated balances in utilizing fatty acids (FAs) and other substrates to meet the high energy requirements. As the master transcriptional regulators of lipid metabolism, RXRs become particularly important for the energy needs of the heart. Accumulating evidence suggested that RXRs may exert direct beneficial effects in the heart both through heterodimerization with other nuclear receptors (NRs) and homodimerization, thus standing as suitable targets for treating in cardiovascular diseases. Although compounds that target RXRs are promising drugs, their use is limited by toxicity. A better understanding of the structural biology of RXRs in cardiovascular disease should enable the rational design of more selective nuclear receptor modulators to overcome these problems. Here, this review summarizes a brief overview of RXRs structure and versatility of RXR action in the control of cardiovascular diseases. And we also discussed the therapeutic potential of RXR ligand.
Collapse
Affiliation(s)
- Mingyan Shao
- School of Life Science, Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Linghui Lu
- College of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Qian Wang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Lin Ma
- School of Life Science, Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Xue Tian
- School of Life Science, Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Changxiang Li
- College of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Chun Li
- Modern Research Center of Traditional Chinese Medicine, School of Traditional Chinese Material Medica, Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Dongqing Guo
- School of Life Science, Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Qiyan Wang
- School of Life Science, Beijing University of Chinese Medicine, Beijing, 100029, China
| | - Wei Wang
- School of Life Science, Beijing University of Chinese Medicine, Beijing, 100029, China.
| | - Yong Wang
- School of Life Science, Beijing University of Chinese Medicine, Beijing, 100029, China; College of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, 100029, China.
| |
Collapse
|
8
|
Ardenkjær-Larsen J, Rupar K, Sinkevičiūtė G, Petersen PSS, Villarroel J, Lundh M, Barrès R, Rabiee A, Emanuelli B. Insulin-induced serine 22 phosphorylation of retinoid X receptor alpha is dispensable for adipogenesis in brown adipocytes. Adipocyte 2020; 9:142-152. [PMID: 32249683 PMCID: PMC7153655 DOI: 10.1080/21623945.2020.1747352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Insulin action initiates a series of phosphorylation events regulating cellular differentiation, growth and metabolism. We have previously discovered, in a mass spectrometry-based phosphoproteomic study, that insulin/IGF-1 signalling induces phosphorylation of retinoid x receptor alpha (RXRα) at S22 in mouse brown pre-adipocytes. Here, we show that insulin induces the phosphorylation of RXRα at S22 in both brown precursor and mature adipocytes through a pathway involving ERK, downstream of IRS-1 and −2. We also found that RXRα S22 phosphorylation is promoted by insulin and upon re-feeding in brown adipose tissue in vivo, and that insulin-stimulated S22 phosphorylation of RXRα is dampened by diet-induced obesity. We used Rxra knockout cells re-expressing wild type (WT) or S22A non-phosphorylatable forms of RXRα to further characterize the role of S22 in brown adipocytes. Knockout of Rxra in brown pre-adipocytes resulted in decreased lipid accumulation and adipogenic gene expression during differentiation, and re-expression of RxraWT alleviated these effects. However, we observed no significant difference in cells re-expressing the RxraS22A mutant as compared with the cells re-expressing RxraWT. Furthermore, comparison of gene expression during adipogenesis in the WT and S22A re-expressing cells by RNA sequencing revealed similar transcriptomic profiles. Thus, our data propose a dispensable role for RXRα S22 phosphorylation in adipogenesis and transcription in differentiating brown pre-adipocytes.
Collapse
Affiliation(s)
- Jacob Ardenkjær-Larsen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kaja Rupar
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Goda Sinkevičiūtė
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Patricia S. S. Petersen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Julia Villarroel
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten Lundh
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Romain Barrès
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Atefeh Rabiee
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Brice Emanuelli
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
9
|
Guo FF, Xiao M, Wang SY, Zeng T, Cheng L, Xie Q. Downregulation of mitogen-activated protein kinases (MAPKs) in chronic ethanol-induced fatty liver. Toxicol Mech Methods 2020; 30:407-416. [PMID: 32237978 DOI: 10.1080/15376516.2020.1747126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Mitogen-activated protein kinases (MAPKs) are versatile proteins that have been suggested to be involved in the regulation of lipid metabolism. This study was designed to investigate the responses of MAPK signaling to chronic ethanol exposure in vivo and in vitro, and try to explore its role in the pathogenesis of alcoholic fatty liver (AFL). Mice were fed with Lieber-Decarli liquid diet (5% ethanol, w/v) for 4 weeks to induce fatty liver, and the chronological changes of MAPK phosphorylation were measured using western blotting. We found that chronic ethanol feeding led to accumulation of triglyceride (TG), decreased phosphorylation of MAPKs, decreased protein level of peroxisomal proliferator activation receptor α (PPARα), and increased protein expression of cytochrome P4502E1 (CYP2E1) in mice liver. In vitro study showed that overexpression of CYP2E1 blunted the response of MAPKs to ethanol, and MAPK phosphatase 1 (MKP-1) knockdown by siRNA led to upregulation of PPARα protein level. Lastly, epidermal growth factor (EGF), a well-known MAPK activator, significantly suppressed chronic ethanol-induced hepatic fat accumulation and decline of PPARα expression in mice liver. Collectively, MAPK suppression, possibly due to the activation of hepatic CYP2E1, may be involved in chronic ethanol-induced hepatic steatosis.
Collapse
Affiliation(s)
- Fang-Fang Guo
- Department of Pharmacy, Qilu Hospital of Shandong University, Jinan, China
| | - Mo Xiao
- Institute of Toxicology, School of Public Health, Shandong University, Jinan, China
| | - Shao-Yi Wang
- Department of Orthopaedic Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Tao Zeng
- Institute of Toxicology, School of Public Health, Shandong University, Jinan, China
| | - Lei Cheng
- Department of Orthopaedic Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Qing Xie
- Department of Pharmacy, Qilu Hospital of Shandong University, Jinan, China
| |
Collapse
|
10
|
Jiang H, Li R, Zhang Z, Chang C, Liu Y, Liu Z, He Q, Wang Q. Retinoid X receptor α (RXRα)-mediated erythroid-2-related factor-2 (NRF2) inactivation contributes to N,N-dimethylformamide (DMF)-induced oxidative stress in HL-7702 and HuH6 cells. J Appl Toxicol 2019; 40:470-482. [PMID: 31875996 DOI: 10.1002/jat.3919] [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: 05/18/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 12/24/2022]
Abstract
N,N-dimethylformamide (DMF) is a colorless industrial solvent that is frequently used for chemical reactions. Epidemiologic studies and clinical case reports have consistently indicated that the main toxic effect after exposure to DMF is hepatotoxicity. Previous studies have suggested that oxidative stress is the pivotal molecular event of DMF-mediated hepatotoxicity; however, its underlying mechanism remains unclear. In this study, we found that DMF (0-150 mM) exposure induced an increase in reactive oxygen species (ROS) levels and inhibited the transcriptional activity of nuclear factor erythroid-2-related factor-2 (NRF2) in a dose-dependent manner. Subsequently, our research revealed that the elevated ROS levels and the decline in NRF2-mediated anti-oxidative response in HL-7702 and HuH6 cells might be due to the DMF-induced accumulation of retinoid X receptor α (RXRα) protein. Further investigation demonstrated that phosphorylation of the RXRα protein, which is mediated by the activation of extracellular signal-regulated kinase (ERK), leads to the inhibition of RXRα protein degradation and in turn the accumulation of RXRα after DMF exposure. These findings provide information that improves our understanding of the role of RXRα in DMF-induced hepatotoxicity.
Collapse
Affiliation(s)
- Hongmei Jiang
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Ruobi Li
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Zhen Zhang
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Chong Chang
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Ye Liu
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Ziqi Liu
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Qianmei He
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Qing Wang
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| |
Collapse
|
11
|
A phosphorylation-deficient mutant of retinoid X receptor α at Thr 167 alters fasting response and energy metabolism in mice. J Transl Med 2019; 99:1470-1483. [PMID: 31152145 PMCID: PMC6759383 DOI: 10.1038/s41374-019-0266-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 04/14/2019] [Accepted: 04/29/2019] [Indexed: 11/09/2022] Open
Abstract
Retinoid X receptor α (RXRα) has a conserved phosphorylation motif at threonine 162 (humans) and threonine 167 (mice) within the DNA-binding domain. Here we have generated RXRα knock-in mice (RxrαT167A) bearing a single mutation of Thr 167 to alanine and examined the roles of Thr 167 in the regulation of energy metabolism within adipose, muscle, and liver tissues. RxrαT167A mice exhibited down-regulation of metabolic pathways converting glucose to fatty acids, such as acetyl-CoA carboxylase in the white adipose tissue (WAT) and ATP citrate lyase in the muscle. They also reduced gene expression for genes related to fatty acid catabolism and triglyceride synthesis in WAT and controlled heat factors such as adrenergic receptor β1 in muscles. In contrast, hepatic gluconeogenic pathways and synthetic pathways related to fatty acids remained unaffected by this mutation. Expression of multiple genes that were affected by the Thr 167 mutation in adipose tissue exhibited clear response to LG100268, a synthetic RXR agonist. Thus, the altered gene expression in mutant mice adipose appeared to be a direct effect of RXRα Thr 167 mutation and by some secondary effect of the mutation. Blood glucose levels remained normal in RxrαT167A during feeding, as observed with RXRα wild-type mice. However, RxrαT167A mice exhibited an attenuated decrease of blood glucose levels that occurred after fasting. This attenuation correlated with a concomitant down-regulation of lipid metabolism in WAT and was associated with RXRα phosphorylation at Thr 167. Thus, Thr 167 enabled RXRα to coordinate these three organs for regulation of energy metabolism and maintenance of glucose homeostasis.
Collapse
|
12
|
Shamilov R, Aneskievich BJ. Intrinsic Disorder in Nuclear Receptor Amino Termini: From Investigational Challenge to Therapeutic Opportunity. NUCLEAR RECEPTOR RESEARCH 2019. [DOI: 10.32527/2019/101417] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Rambon Shamilov
- Graduate Program in Pharmacology & Toxicology, University of Connecticut, Storrs, CT 06269-3092, USA
| | - Brian J. Aneskievich
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269-3092, USA
| |
Collapse
|
13
|
Zhang X, Zhou H, Su Y. Targeting truncated RXRα for cancer therapy. Acta Biochim Biophys Sin (Shanghai) 2016; 48:49-59. [PMID: 26494413 DOI: 10.1093/abbs/gmv104] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 08/24/2015] [Indexed: 01/08/2023] Open
Abstract
Retinoid X receptor-alpha (RXRα), a unique member of the nuclear receptor superfamily, is a well-established drug target, representing one of the most important targets for pharmacologic interventions and therapeutic applications for cancer. However, how RXRα regulates cancer cell growth and how RXRα modulators suppress tumorigenesis are poorly understood. Altered expression and aberrant function of RXRα are implicated in the development of cancer. Previously, several studies had demonstrated the presence of N-terminally truncated RXRα (tRXRα) proteins resulted from limited proteolysis of RXRα in tumor cells. Recently, we discovered that overexpression of tRXRα can promote tumor growth by interacting with tumor necrosis factor-alpha-induced phosphoinositide 3-kinase and NF-κB signal transduction pathways. We also identified nonsteroidal anti-inflammatory drug Sulindac and analogs as effective inhibitors of tRXRα activities via a unique binding mechanism. This review discusses the emerging roles of tRXRα and modulators in the regulation of cancer cell survival and death as well as inflammation and our recent understanding of tRXRα regulation by targeting the alternate binding sites on its surface.
Collapse
Affiliation(s)
- Xiaokun Zhang
- School of Pharmaceutical Sciences, Xiamen University, Xiamen 361102, China Sanford Burnham Prebys Medical Discovery Institute, Cancer Center, La Jolla, CA 92037, USA
| | - Hu Zhou
- School of Pharmaceutical Sciences, Xiamen University, Xiamen 361102, China
| | - Ying Su
- School of Pharmaceutical Sciences, Xiamen University, Xiamen 361102, China Sanford Burnham Prebys Medical Discovery Institute, Cancer Center, La Jolla, CA 92037, USA
| |
Collapse
|
14
|
Up-regulation of steroid biosynthesis by retinoid signaling: Implications for aging. Mech Ageing Dev 2015; 150:74-82. [PMID: 26303142 DOI: 10.1016/j.mad.2015.08.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 07/14/2015] [Accepted: 08/15/2015] [Indexed: 11/24/2022]
Abstract
Retinoids (vitamin A and its derivatives) are critical for a spectrum of developmental and physiological processes, in which steroid hormones also play indispensable roles. The StAR protein predominantly regulates steroid biosynthesis in steroidogenic tissues. We have reported that regulation of retinoid, especially atRA and 9-cis RA, responsive StAR transcription is largely mediated by an LXR-RXR/RAR heterodimeric motif in the mouse StAR promoter. Herein we demonstrate that retinoids are capable of enhancing StAR protein, P-StAR, and steroid production in granulosa, adrenocortical, glial, and epidermal cells. Whereas transient expression of RARα and RXRα enhanced 9-cis RA induced StAR gene transcription, silencing of RXRα with siRNA, decreased StAR and steroid levels. An oligonucleotide probe encompassing an LXR-RXR/RAR motif bound to adrenocortical and epidermal keratinocyte nuclear proteins in EMSAs. ChIP studies revealed association of RARα and RXRα with the StAR proximal promoter. Further studies demonstrated that StAR mRNA levels decreased in diseased and elderly men and women skin tissues and that atRA could restore steroidogenesis in epidermal keratinocytes of aged individuals. These findings provide novel insights into the relevance of retinoid signaling in the up-regulation of steroid biosynthesis in various target tissues, and indicate that retinoid therapy may have important implications in age-related complications and diseases.
Collapse
|
15
|
Abstract
Acute promyelocytic leukemia (APL) is a treatment success story. From a highly deadly disease it was turned into a highly curable disease by the introduction of differentiation-induction therapy with all-trans retinoic acid (ATRA) in the 1990's. During the last quarter of century, ATRA and other retinoids were used for the treatment and prevention of other cancers and even other diseases. The results were less spectacular, but nevertheless important. Progress has been made toward understanding the mechanism of action of retinoids in different physiological and pathological contexts. For some diseases, specific genetic backgrounds were found to confer responsiveness to retinoid therapy. Therapies that include retinoids and other modalities are very diverse and used both for combined targeting of multiple pathways and for diminishing toxicity.
Collapse
|
16
|
A Role for Acyclic Retinoid in the Chemoprevention of Hepatocellular Carcinoma: Therapeutic Strategy Targeting Phosphorylated Retinoid X Receptor-α. Diseases 2014. [DOI: 10.3390/diseases2030226] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
|
17
|
Manna PR, Slominski AT, King SR, Stetson CL, Stocco DM. Synergistic activation of steroidogenic acute regulatory protein expression and steroid biosynthesis by retinoids: involvement of cAMP/PKA signaling. Endocrinology 2014; 155:576-91. [PMID: 24265455 PMCID: PMC3891939 DOI: 10.1210/en.2013-1694] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Both retinoic acid receptors (RARs) and retinoid X receptors (RXRs) mediate the action of retinoids that play important roles in reproductive development and function, as well as steroidogenesis. Regulation of steroid biosynthesis is principally mediated by the steroidogenic acute regulatory protein (StAR); however, the modes of action of retinoids in the regulation of steroidogenesis remain obscure. In this study we demonstrate that all-trans retinoic acid (atRA) enhances StAR expression, but not its phosphorylation (P-StAR), and progesterone production in MA-10 mouse Leydig cells. Activation of the protein kinase A (PKA) cascade, by dibutyrl-cAMP or type I/II PKA analogs, markedly increased retinoid-responsive StAR, P-StAR, and steroid levels. Targeted silencing of endogenous RARα and RXRα, with small interfering RNAs, resulted in decreases in 9-cis RA-stimulated StAR and progesterone levels. Truncation of and mutational alterations in the 5'-flanking region of the StAR gene demonstrated the importance of the -254/-1-bp region in retinoid responsiveness. An oligonucleotide probe encompassing an RXR/liver X receptor recognition motif, located within the -254/-1-bp region, specifically bound MA-10 nuclear proteins and in vitro transcribed/translated RXRα and RARα in EMSAs. Transcription of the StAR gene in response to atRA and dibutyrl-cAMP was influenced by several factors, its up-regulation being dependent on phosphorylation of cAMP response-element binding protein (CREB). Chromatin immunoprecipitation studies revealed the association of phosphorylation of CREB, CREB binding protein, RXRα, and RARα to the StAR promoter. Further studies elucidated that hormone-sensitive lipase plays an important role in atRA-mediated regulation of the steroidogenic response that involves liver X receptor signaling. These findings delineate the molecular events by which retinoids influence cAMP/PKA signaling and provide additional and novel insight into the regulation of StAR expression and steroidogenesis in mouse Leydig cells.
Collapse
Affiliation(s)
- Pulak R Manna
- Department of Cell Biology and Biochemistry (P.R.M., S.R.K., D.M.S.), Department of Dermatology and Pathology (C.L.S.), Texas Tech University Health Sciences Center, Lubbock, Texas 79430; and Department of Pathology and Laboratory Medicine (A.T.S.), University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | | | | | | | | |
Collapse
|
18
|
Halftermeyer J, Le Bras M, De Thé H. [RXR, a key member of the oncogenic complex in acute promyelocytic leukemia]. Med Sci (Paris) 2011; 27:973-8. [PMID: 22130024 DOI: 10.1051/medsci/20112711013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Acute promyelocytic leukaemia (APL) is induced by fusion proteins always implying the retinoic acid receptor RARa. Although PML-RARa and other fusion oncoproteins are able to bind DNA as homodimers, in vivo they are always found in association with the nuclear receptor RXRa (Retinoid X Receptor). Thus, RXRa is an essential cofactor of the fusion protein for the transformation. Actually, RXRa contributes to several aspects of in vivo -transformation: RARa fusion:RXRa hetero-oligomeric complexes bind DNA with a much greater affinity than RARa fusion homodimers. Besides, PML-RARa:RXRa recognizes an enlarged repertoire of DNA binding sites. Thus the association between fusion proteins and RXRa regulates more genes than the homodimer alone. Titration of RXRa by the fusion protein may also play a role in the transformation process, as well as post-translational modifications of RXRa in the complex. Finally, RXRa is required for rexinoid-induced APL differentiation. Thus, RXRa is a key member of the oncogenic complex.
Collapse
Affiliation(s)
- Juliane Halftermeyer
- Institut universitaire d'hématologie, Inserm U944, Hôpital Saint-Louis, 75010 Paris, France.
| | | | | |
Collapse
|
19
|
Dawson MI, Xia Z. The retinoid X receptors and their ligands. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:21-56. [PMID: 22020178 DOI: 10.1016/j.bbalip.2011.09.014] [Citation(s) in RCA: 258] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 08/23/2011] [Accepted: 09/23/2011] [Indexed: 12/12/2022]
Abstract
This chapter presents an overview of the current status of studies on the structural and molecular biology of the retinoid X receptor subtypes α, β, and γ (RXRs, NR2B1-3), their nuclear and cytoplasmic functions, post-transcriptional processing, and recently reported ligands. Points of interest are the different changes in the ligand-binding pocket induced by variously shaped agonists, the communication of the ligand-bound pocket with the coactivator binding surface and the heterodimerization interface, and recently identified ligands that are natural products, those that function as environmental toxins or drugs that had been originally designed to interact with other targets, as well as those that were deliberately designed as RXR-selective transcriptional agonists, synergists, or antagonists. Of these synthetic ligands, the general trend in design appears to be away from fully aromatic rigid structures to those containing partial elements of the flexible tetraene side chain of 9-cis-retinoic acid. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).
Collapse
Affiliation(s)
- Marcia I Dawson
- Cancer Center, Sanford-Burn Medical Research Institute, 10901 North Torrey Pines Rd., La Jolla, CA 93207, USA.
| | | |
Collapse
|
20
|
Urushitani H, Katsu Y, Ohta Y, Shiraishi H, Iguchi T, Horiguchi T. Cloning and characterization of retinoid X receptor (RXR) isoforms in the rock shell, Thais clavigera. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2011; 103:101-111. [PMID: 21414284 DOI: 10.1016/j.aquatox.2011.02.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Revised: 02/09/2011] [Accepted: 02/12/2011] [Indexed: 05/30/2023]
Abstract
The organotin compounds tributyltin (TBT) and triphenyltin (TPT) belong to a diverse group of widely distributed environmental pollutants that induce imposex in gastropods. These organotins have high affinity for retinoid X receptor (RXR), which is a transcription factor activated by retinoids, such as 9-cis retinoic acid (9cRA), in vertebrates. However, the molecular mechanisms underlying the regulation of RXR by retinoids and organotins have not been clarified in gastropods. We isolated two isoforms of RXR cDNAs, RXR isoform 1 (TcRXR-1) and RXR isoform 2 (TcRXR-2), in the rock shell Thais clavigera. The deduced amino acid sequences of TcRXR-1 and TcRXR-2 are highly homologous with those of other gastropods. These TcRXR isoforms displayed 9cRA-dependent activation of transcription in a reporter gene assay using COS-1 cells. The transcriptional activity of TcRXR-2, the encoded protein of which has five additional amino acids in the T-box of the C domain, was significantly lower than that of TcRXR-1. Decreases of the transcriptional activity by TcRXR-1 were observed when more than equal amount of TcRXR-2 fused expression vector was existed in a co-transfection assay. Immunoblot analysis showed several shifted bands for TcRXR isoforms resulting from phosphorylation. Mutation of potential phosphorylation sites from serine to alanine in the A/B domain of TcRXR-1 showed that, in the S89A/S103A mutant, there was a band shift and significantly higher transcriptional activity than in the controls when stimulated with 9cRA. Our findings could contribute to a better understanding of the role of interactions between RXR and retinoids and organotins, not only in the induction mechanism of imposex in gastropods but also in the endocrinology of mollusks.
Collapse
Affiliation(s)
- Hiroshi Urushitani
- Research Center for Environmental Risk, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | | | | | | | | | | |
Collapse
|
21
|
Zhang Z, Kovalenko P, Cui M, Desmet M, Clinton SK, Fleet JC. Constitutive activation of the mitogen-activated protein kinase pathway impairs vitamin D signaling in human prostate epithelial cells. J Cell Physiol 2010; 224:433-42. [PMID: 20432439 DOI: 10.1002/jcp.22139] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We studied the effect of prolonged activation of mitogen-activated protein kinase (MAPK) signaling on 1,25 dihydroxyvitamin D (1,25(OH)(2)D(3)) action in the immortalized human prostate epithelial cell line RWPE1 and its Ki-Ras transformed clone RWPE2. 1,25(OH)(2)D(3)-treatment caused growth arrest and induced gene expression in both cell lines but the response was blunted in RWPE2 cells. Vitamin D receptor (VDR) levels were lower in RWPE2 cells but VDR over-expression did not increase vitamin-D-mediated gene transcription in either cell line. In contrast, MAPK inhibition restored normal vitamin D transcriptional responses in RWPE2 cells and MAPK activation with constitutively active MEK1R4F reduced vitamin-D-regulated transcription in RWPE1 cells. 1,25(OH)(2)D(3)-mediated transcription depends upon the VDR and its heterodimeric partner the retinoid X receptor (RXR) so we studied whether changes in the VDR-RXR transcription complex occur in response to MAPK activation. Mutation of putative phosphorylation sites in the activation function 1 (AF-1) domain (S32A, T82A) of RXRalpha restored 1,25(OH)(2)D(3)-mediated transactivation in RWPE2 cells. Mammalian two-hybrid and co-immunoprecipitation assays revealed a vitamin-D-independent interaction between steroid receptor co-activator-1 (SRC-1) and RXRalpha that was reduced by MAPK activation and was restored in RWPE2 cells by mutating S32 and T82 in the RXRalpha AF-1 domain. Our data show that a common contributor to cancer development, prolonged activation of MAPK signaling, impairs 1,25(OH)(2)D(3)-mediated transcription in prostate epithelial cells. This is due in part to the phosphorylation of critical amino acids in the RXRalpha AF-1 domain and impaired co-activator recruitment.
Collapse
Affiliation(s)
- Zhentao Zhang
- Department of Foods and Nutrition, Purdue University, West Lafayette, Indiana 47907-2059, USA
| | | | | | | | | | | |
Collapse
|
22
|
Mark M, Ghyselinck NB, Chambon P. Function of retinoic acid receptors during embryonic development. NUCLEAR RECEPTOR SIGNALING 2009; 7:e002. [PMID: 19381305 PMCID: PMC2670431 DOI: 10.1621/nrs.07002] [Citation(s) in RCA: 255] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 03/13/2009] [Indexed: 12/31/2022]
Abstract
Retinoids, the active metabolites of vitamin A, regulate complex gene networks involved in vertebrate morphogenesis, growth, cellular differentiation and homeostasis. Studies performed in vitro, using either acellular systems or transfected cells, have shown that retinoid actions are mediated through heterodimers between the RAR and RXR nuclear receptors. However, in vitro studies indicate what is possible, but not necessarily what is actually occurring in vivo, because they are performed under non-physiological conditions. Therefore, genetic approaches in the animal have been be used to determine the physiological functions of retinoid receptors. Homologous recombination in embryonic stem cells has been used to generate germline null mutations of the RAR- and RXR-coding genes in the mouse. As reviewed here, the generation of such germline mutations, combined with pharmacological approaches to block the RA signalling pathway, has provided genetic evidence that RAR/RXR heterodimers are indeed the functional units transducing the RA signal during prenatal development. However, due to (i) the complexity in “hormonal” signalling through transduction by the multiple RARs and RXRs, (ii) the functional redundancies (possibly artefactually generated by the mutations) within receptor isotypes belonging to a given family, and (iii) in utero or early postnatal lethality of certain germline null mutations, these genetic studies have failed to reveal all the physiological functions of RARs and RXRs, notably in adults. Spatio-temporally-controlled somatic mutations generated in given cell types/tissues and at chosen times during postnatal life, will be required to reveal all the functions of RAR and RXR throughout the lifetime of the mouse.
Collapse
Affiliation(s)
- Manuel Mark
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Département de Biologie Cellulaire and Développement, Strasbourg, France
| | | | | |
Collapse
|
23
|
Shimizu M, Takai K, Moriwaki H. Strategy and mechanism for the prevention of hepatocellular carcinoma: phosphorylated retinoid X receptor alpha is a critical target for hepatocellular carcinoma chemoprevention. Cancer Sci 2009; 100:369-74. [PMID: 19068086 PMCID: PMC11159360 DOI: 10.1111/j.1349-7006.2008.01045.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a major health care problem worldwide. The prognosis of patients with HCC is poor because even in the early stages when surgical treatment might be expected to be curative, the incidence of recurrence in patients with underlying cirrhosis is very high due to multicentric carcinogenesis. Therefore, strategies to prevent recurrence and second primary HCC are required to improve the prognosis. One of the most practical approaches to prevent the multicentric development of HCC is 'clonal deletion' therapy, which is defined as the removal of latent (i.e. invisible) (pre)malignant clones from the liver in a hypercarcinogenic state. Retinoids, a group of structural and functional analogs of vitamin A, exert their biological function primarily through two distinct nuclear receptors, retinoic acid receptors and retinoid X receptors (RXR), and abnormalities in the expression and function of these receptors are highly associated with the development of various cancers, including HCC. In particular, a malfunction of RXRalpha due to phosphorylation by the Ras-mitogen-activated protein kinase signaling pathway is profoundly associated with the development of HCC and thus may be a critical target for HCC chemoprevention. Acyclic retinoid, which has been clinically shown to reduce the incidence of a post-therapeutic recurrence of HCC, can inhibit Ras activity and phosphorylation of the extracellular signal-regulated kinase and RXRalpha proteins. In conclusion, the inhibition of RXRalpha phosphorylation and the restoration of its physiological function as a master regulator for nuclear receptors may be a potentially effective strategy for HCC chemoprevention and clonal deletion. Acyclic retinoid, which targets phosphorylated RXRalpha, may thus play a critical role in preventing the development of multicentric HCC.
Collapse
Affiliation(s)
- Masahito Shimizu
- Department of Medicine, Gifu University Graduate School of Medicine, Gifu, Japan.
| | | | | |
Collapse
|
24
|
Cui M, Zhao Y, Hance KW, Shao A, Wood RJ, Fleet JC. Effects of MAPK signaling on 1,25-dihydroxyvitamin D-mediated CYP24 gene expression in the enterocyte-like cell line, Caco-2. J Cell Physiol 2009; 219:132-42. [PMID: 19097033 DOI: 10.1002/jcp.21657] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We examined the role of the extracellular signal regulated kinases (ERK) in 1,25-dihydroxyvitamin D (1,25(OH)(2)D(3))-induced gene expression in the differentiated Caco-2 cells. 1,25(OH)(2)D(3)-regulated expression of the 25-hydroxyvitamin D, 24-hydroxylase (CYP24) gene (both natural gene and promoter construct) was strongly modulated by altering ERK activity (i.e., reduced by MEK inhibitors and dominant negative (dn) ERK1 and ERK2, activated by epidermal growth factor) but ERK inhibition had no effect on 1,25(OH)(2)D(3)-regulated expression of the transient receptor potential cation channel, subfamily V, member 6 (TRPV6). ERK5-mediated phosphorylation of the transcription factor Ets-1 enhanced 1,25(OH)(2)D(3)-mediated CYP24 gene transcription in proliferating but not differentiated Caco-2 cells due to reduced levels of ERK5 and Ets-1 (total and phosphoprotein levels) in differentiated cells. MEK inhibition reduced 1,25(OH)(2)D(3)-induced 3X-VDRE promoter activity but had no impact on the association of vitamin D receptor (VDR) with chromatin suggesting a role for co-activator recruitment in ERK-modulation of vitamin D-regulated CYP24 gene activation. Chromatin immunoprecipitation assays revealed that the ERK1/2 target, mediator 1 (MED1), is recruited to the CYP24, but not the TRPV6, promoter following 1,25(OH)(2)D(3) treatment. MED1 phosphorylation was sensitive to activators and inhibitors of the ERK1/2 signaling and MED1 siRNA reduced 1,25(OH)(2)D(3)-regulated human CYP24 promoter activity. This suggests ERK1/2 signaling enhances 1,25(OH)(2)D(3) effects on the CYP24 promoter by MED1-mediated events. Our data show that there are both promoter-specific and cell stage-specific roles for the ERK signaling pathway on 1,25(OH)(2)D(3)-mediated gene induction in enterocyte-like Caco-2 cells.
Collapse
Affiliation(s)
- Min Cui
- Department of Foods and Nutrition, Purdue University, West Lafayette, Indiana 47906-2059, USA
| | | | | | | | | | | |
Collapse
|
25
|
Shimizu M, Moriwaki H. Synergistic Effects of PPARgamma Ligands and Retinoids in Cancer Treatment. PPAR Res 2008; 2008:181047. [PMID: 18528526 PMCID: PMC2408709 DOI: 10.1155/2008/181047] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 04/21/2008] [Accepted: 05/01/2008] [Indexed: 01/04/2023] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily. The activation of PPARs by their specific ligands is regarded as one of the promising strategies to inhibit cancer cell growth. However, recent clinical trials targeting several common cancers showed no beneficial effect when PPAR ligands are used as a monotherapy. Retinoid X receptors (RXRs), which play a critical role in normal cell proliferation as a master regulator for nuclear receptors, preferentially form heterodimers with PPARs. A malfunction of RXRalpha due to phosphorylation by the Ras/MAPK signaling pathway is associated with the development of certain types of human malignancies. The activation of PPARgamma/RXR heterodimer by their respective ligands synergistically inhibits cell growth, while inducing apoptosis in human colon cancer cells when the phosphorylation of RXRalpha was inhibited. We herein review the synergistic antitumor effects produced by the combination of the PPAR, especially PPARgamma, ligands plus other agents, especially retinoids, in a variety of human cancers. We also focus on the phosphorylation of RXRalpha because the inhibition of RXRalpha phosphorylation and the restoration of its physiological function may activate PPAR/RXR heterodimer and, therefore, be a potentially effective and critical strategy for the inhibition of cancer cell growth.
Collapse
Affiliation(s)
- Masahito Shimizu
- Department of Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan
| | - Hisataka Moriwaki
- Department of Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan
| |
Collapse
|
26
|
Cheung BB, Bell J, Raif A, Bohlken A, Yan J, Roediger B, Poljak A, Smith S, Lee M, Thomas WD, Kavallaris M, Norris M, Haber M, Liu HL, Zajchowski D, Marshall GM. The estrogen-responsive B box protein is a novel regulator of the retinoid signal. J Biol Chem 2006; 281:18246-56. [PMID: 16636064 DOI: 10.1074/jbc.m600879200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retinoic acid (RA) induces growth arrest, cell death, and differentiation in many human cancer cells in vitro and has entered routine clinical use for the treatment of several human cancer types. One mechanism by which cancer cells evade retinoid-induced effects is through repression of retinoic acid receptor beta (RARbeta) gene transcription. The RA response element beta (betaRARE) is the essential DNA sequence required for retinoid-induced RARbeta transcription. Here we show that the estrogen-responsive B box protein (EBBP), a member of the RING-B box-coiled-coil protein family, is a betaRARE-binding protein. EBBP undergoes serine threonine phosphorylation and enhanced protein stability after RA treatment. Following RA treatment, we also observed increased nuclear EBBP levels in aggregates with the promyelocytic leukemia protein at promyelocytic leukemia nuclear bodies. EBBP enhanced RA-responsive RARbeta transcription in RA-sensitive and -resistant cancer cells, which were resistant to both a histone deacetylase inhibitor and a demethylating agent. EBBP-specific small interfering RNA reduced basal and RA-induced RARbeta expression. EBBP increased betaRARE-transactivating function through its coiled-coil domain. Taken together, our work suggests that EBBP may have a pivotal role in the retinoid anti-cancer signal.
Collapse
Affiliation(s)
- Belamy B Cheung
- Children's Cancer Institute Australia for Medical Research, Randwick, New South Wales 2031, Australia
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Mark M, Ghyselinck NB, Chambon P. Function of retinoid nuclear receptors: lessons from genetic and pharmacological dissections of the retinoic acid signaling pathway during mouse embryogenesis. Annu Rev Pharmacol Toxicol 2006; 46:451-80. [PMID: 16402912 DOI: 10.1146/annurev.pharmtox.46.120604.141156] [Citation(s) in RCA: 470] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Retinoic acid (RA) is involved in vertebrate morphogenesis, growth, cellular differentiation, and tissue homeostasis. The use of in vitro systems initially led to the identification of nuclear receptor RXR/RAR heterodimers as possible transducers of the RA signal. To unveil the physiological functions of RARs and RXRs, genetic and pharmacological studies have been performed in the mouse. Together, their results demonstrate that (a) RXR/RAR heterodimers in which RXR is either transcriptionally active or silent are involved in the transduction of the RA signal during prenatal development, (b) specific RXRalpha/RAR heterodimers are required at many distinct stages during early embryogenesis and organogenesis, (c) the physiological role of RA and its receptors cannot be extrapolated from teratogenesis studies using retinoids in excess. Additional cell type-restricted and temporally controlled somatic mutagenesis is required to determine the functions of RARs and RXRs during postnatal life.
Collapse
Affiliation(s)
- Manuel Mark
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Institut Clinique de la Souris, Centre National de la Recherche Scientifique/INSERM, Université Louis Pasteur de Strasbourg, Collège de France, 67404 Illkirch Cedex, CU de Strasbourg, France
| | | | | |
Collapse
|
28
|
Fu H, Yang G, Lu F, Wang R, Yao L, Lu Z. Transcriptional up-regulation of restin by all-trans retinoic acid through STAT1 in cancer cell differentiation process. Biochem Biophys Res Commun 2006; 343:1009-16. [PMID: 16574066 DOI: 10.1016/j.bbrc.2006.02.176] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Accepted: 02/28/2006] [Indexed: 11/15/2022]
Abstract
RESTIN, a member of the melanoma-associated antigen superfamily, is a nuclear protein induced by atRA (all-trans retinoic acid) in HL60 cells. HeLa cells stably transfected with restin results in G1 cell cycle arrest. How this gene is regulated by atRA in the cell differentiation process is still unclear. In this study, we observed that up-regulation of restin was present during the atRA-induced HL60 cell differentiation process, suggesting the functional relevance between RESTIN and atRA-induced cellular effects. In order to further define the transcriptional regulation of restin by atRA, we analyzed the promoter region of restin. About 2.1kb 5' flanking sequence of this gene was cloned into vector pGL3 and its core promoter region was identified through systemic deletions. Interestingly, restin promoter containing several potential consensus-binding sites of STAT-1alpha was activated by atRA in ER(+) MCF-7 cells but not in ER(-) MDA-MB-231 cells, over-expression of STAT-1alpha in latter rescued the activation effect of restin promoter in response to atRA and IFNgamma. Our evidence supported that STAT-1alpha plays an important role in the atRA-induced transcriptional up-regulation of restin, which was associated with the atRA-induced HL60 cell differentiation and potentially mediated the downstream effects of atRA signal pathway via STAT-1alpha in some cancer cells.
Collapse
Affiliation(s)
- Haiyan Fu
- Department of Biochemistry and Molecular Biology, State Key Lab of Cancer Biology, Fourth Military Medical University, Xi'an 710032, PR China
| | | | | | | | | | | |
Collapse
|
29
|
Mann KK, Padovani AMS, Guo Q, Colosimo AL, Lee HY, Kurie JM, Miller WH. Arsenic trioxide inhibits nuclear receptor function via SEK1/JNK-mediated RXRalpha phosphorylation. J Clin Invest 2005; 115:2924-33. [PMID: 16184197 PMCID: PMC1224295 DOI: 10.1172/jci23628] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Accepted: 07/19/2005] [Indexed: 01/01/2023] Open
Abstract
We have previously published that 2 proven treatments for acute promyelocytic leukemia, As2O3 and retinoic acid, can be antagonistic in vitro. We now report that As2O3 inhibits ligand-induced transcription of the retinoic acid receptor, as well as other nuclear receptors that heterodimerize with the retinoid X receptor alpha (RXRalpha). As2O3 did not inhibit transactivation of the estrogen receptor or the glucocorticoid receptor, which do not heterodimerize with RXRalpha. We further show that As2O3 inhibits expression of several target genes of RXRalpha partners. Phosphorylation of RXRalpha has been reported to inhibit nuclear receptor signaling, and we show by in vivo labeling and phosphoamino acid detection that As2O3 phosphorylated RXRalpha in the N-terminal ABC region exclusively on serine residues. Consistent with our previous data implying a role for JNK in As2O3-induced apoptosis, we show that pharmacologic or genetic inhibition of JNK activation decreased As2O3-induced RXRalpha phosphorylation and blocked the effects of As2O3 on RXRalpha-mediated transcription. A mutational analysis indicated that phosphorylation of a specific serine residue, S32, was primarily responsible for inhibition of RXRalpha-mediated transcription. These data may provide some insight into the rational development of chemotherapeutic combinations involving As2O3 as well as into molecular mechanisms of arsenic-induced carcinogenesis resulting from environmental exposure.
Collapse
Affiliation(s)
- Koren K Mann
- Montréal Centre for Experimental Therapeutics in Cancer, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montréal, Québec, Canada
| | | | | | | | | | | | | |
Collapse
|
30
|
Drdová B, Vachtenheim J. A role for p21 (WAF1) in the cAMP-dependent differentiation of F9 teratocarcinoma cells into parietal endoderm. Exp Cell Res 2004; 304:293-304. [PMID: 15707594 DOI: 10.1016/j.yexcr.2004.10.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2004] [Revised: 10/12/2004] [Accepted: 10/30/2004] [Indexed: 11/24/2022]
Abstract
Combined treatment of teratocarcinoma F9 cells with retinoic acid and dibutyryl-cAMP induces the differentiation into cells with a phenotype resembling parietal endoderm. We show that the levels of cyclin-dependent kinase inhibitor p21/WAF1/Cip1 (p21) protein and mRNA are dramatically elevated at the end of this differentiation, concomitantly with the appearance of p21 in the immunoprecipitated CDK2-cyclin E complex. The induction of differentiation markers could not be achieved by expression of ectopic p21 alone and still required treatment with differentiation agents. Clones of F9 cells transfected with sense or antisense p21 cDNA constructs revealed, upon differentiation, upregulated levels of mRNA for thrombomodulin, a parietal endoderm-specific marker, or increased fraction of cells in sub-G1 phase of the cell cycle, respectively. Consistent with this observation, whereas p21 was strictly nuclear in undifferentiated cells, a large proportion of differentiated cells had p21 localized also in the cytoplasm, a site associated with the antiapoptotic function of p21. Furthermore, p21 activated the thrombomodulin promoter in transient reporter assays and the p21 mutant defective in binding to cyclin E was equally efficient in activation. The promoter activity in differentiated cells was reduced by cotransfection of p21-specific siRNA or antisense cDNA. Coexpression of p21 increased the activity of the GAL-p300(1-1303) fusion protein on the GAL sites-containing TM promoter. This implies that p21 might act through a derepression of the p300 N-terminal-residing repression domain, thereby enhancing the p300 coactivator function. As differentiation of F9 cells into parietal endoderm-like cells requires the cAMP signaling, the results together suggest that the cyclin-dependent kinase inhibitor p21 may promote specifically this pathway in F9 cells.
Collapse
Affiliation(s)
- Blanka Drdová
- Laboratory of Molecular Biology, University Hospital, Clinic of Pneumology, 3rd Faculty of Medicine, Budinova 2, 18000 Prague 8-Bulovka, Czech Republic
| | | |
Collapse
|
31
|
Cammas F, Herzog M, Lerouge T, Chambon P, Losson R. Association of the transcriptional corepressor TIF1beta with heterochromatin protein 1 (HP1): an essential role for progression through differentiation. Genes Dev 2004; 18:2147-60. [PMID: 15342492 PMCID: PMC515292 DOI: 10.1101/gad.302904] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The transcriptional intermediary factor 1beta (TIF1beta) is a corepressor for KRAB-domain-containing zinc finger proteins and is believed to play essential roles in cell physiology by regulating chromatin organization at specific loci through association with chromatin remodeling and histone-modifying activities and recruitment of heterochromatin protein 1 (HP1) proteins. In this study, we have engineered a modified embryonal carcinoma F9 cell line (TIF1beta(HP1box/-)) expressing a mutated TIF1beta protein (TIF1beta(HP1box)) unable to interact with HP1 proteins. Phenotypic analysis of TIF1beta(HP1box/-) and TIF1beta(+/-) cells shows that TIF1beta-HP1 interaction is not required for differentiation of F9 cells into primitive endoderm-like (PrE) cells on retinoic acid (RA) treatment but is essential for further differentiation into parietal endoderm-like (PE) cells on addition of cAMP and for differentiation into visceral endoderm-like cells on treatment of vesicles with RA. Complementation experiments reveal that TIF1beta-HP1 interaction is essential only during a short window of time within early differentiating PrE cells to establish a selective transmittable competence to terminally differentiate on further cAMP inducing signal. Moreover, the expression of three endoderm-specific genes, GATA6, HNF4, and Dab2, is down-regulated in TIF1beta(HP1box/-) cells compared with wild-type cells during PrE differentiation. Collectively, these data demonstrate that the interaction between TIF1beta and HP1 proteins is essential for progression through differentiation by regulating the expression of endoderm differentiation master players.
Collapse
Affiliation(s)
- Florence Cammas
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP/Collège de France, BP10142, 67404 Illkirch, France
| | | | | | | | | |
Collapse
|
32
|
Gimeno A, Zaragozá R, Viña JR, Miralles VJ. Vitamin E activates CRABP-II gene expression in cultured human fibroblasts, role of protein kinase C. FEBS Lett 2004; 569:240-4. [PMID: 15225641 DOI: 10.1016/j.febslet.2004.05.073] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2004] [Revised: 05/17/2004] [Accepted: 05/27/2004] [Indexed: 10/26/2022]
Abstract
The treatment of human fibroblasts with different tocopherols in the presence of retinol caused an increase in cytoplasmic retinoic acid binding protein II (CRABP-II) mRNA and protein. The possibility of an involvement of protein kinase C (PKC) in the response to tocopherols was supported by the results obtained with the PKC-specific inhibitors, calphostin C and bisindolylmaleimide I. The effect of alpha-tocopherol was prevented by okadaic acid, suggesting that a protein phosphatase is responsible for PKC dephosphorylation produced by the presence of tocopherols. The results shown support the hypothesis that phosphorylation/dephosphorylation of RXRalpha via PKC may be involved in the regulation of CRABP-II gene expression.
Collapse
Affiliation(s)
- Amparo Gimeno
- Departamento de Bioquímica y Biología Molecular, Facultades de Farmacia y Medicina, Avda. Vicent Andrés Estellés s/n, Universidad de Valencia, Valencia, Spain
| | | | | | | |
Collapse
|
33
|
Narayanan R, Sepulveda VAT, Falzon M, Weigel NL. The functional consequences of cross-talk between the vitamin D receptor and ERK signaling pathways are cell-specific. J Biol Chem 2004; 279:47298-310. [PMID: 15331595 DOI: 10.1074/jbc.m404101200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The actions of the active metabolite of 1,25-(OH)2D3 (1,25-D) are mediated primarily by the vitamin D receptor (VDR), a member of the nuclear receptor family of ligand-activated transcription factors. Although their ligands cause transcriptional activation, many of the ligands also rapidly activate cellular signaling pathways through mechanisms that have not been fully elucidated. We find that 1,25-D causes a rapid, but sustained activation of ERK (extracellular signal-regulated kinase) in bone cell lines. However, the effect of ERK activation on VDR transcriptional activity was cell line-specific. Inhibition of ERK activation by the MEK inhibitor, U0126, stimulated VDR activity in MC3T3-E1 cells, but inhibited the activity in MG-63 cells as well as in HeLa cells. VDR is not a known target of ERK. We found that the ERK target responsible for reduced VDR activity in MC3T3-E1 cells is RXRalpha. MC3T3-E1 cells express lower levels of RXRbeta and RXRgamma than either HeLa or MG-63 cells. Although overexpression of RXRalpha in MC3T3-E1 cells increased VDR activity, U0126 further enhanced the activity. In contrast, overexpression of RXRgamma stimulated VDR activity but abrogated the stimulation by U0126. Thus, although 1,25-D treatment activates ERK in many cell types, subsequently inducing changes independent of VDR, the effects of treatment with 1,25-D on the transcriptional activity of VDR are RXR isoform-specific. In cells in which RXRalpha is the VDR partner, the transcriptional activation of VDR by 1,25-D is attenuated by the concomitant activation of ERK. In cells utilizing RXRgamma, ERK activation enhances VDR transcriptional activity.
Collapse
Affiliation(s)
- Ramesh Narayanan
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | | | | | | |
Collapse
|
34
|
Li R, Faria TN, Boehm M, Nabel EG, Gudas LJ. Retinoic acid causes cell growth arrest and an increase in p27 in F9 wild type but not in F9 retinoic acid receptor β2 knockout cells. Exp Cell Res 2004; 294:290-300. [PMID: 14980522 DOI: 10.1016/j.yexcr.2003.11.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2003] [Revised: 11/10/2003] [Indexed: 11/16/2022]
Abstract
We have previously shown that an F9 teratocarcinoma retinoic acid receptor beta(2) (RARbeta(2)) knockout cell line exhibits no growth arrest in response to all-trans-retinoic acid (RA), whereas F9 wild type (Wt), F9 RARalpha(-/-), and F9 RARgamma(-/-) cell lines do growth arrest in response to RA. To examine the role of RARbeta(2) in growth inhibition, we analyzed the cell cycle regulatory proteins affected by RA in F9 Wt and F9 RARbeta(2)(-/-) cells. Flow microfluorimetry analyses revealed that RA treatment of F9 Wt cells greatly increased the percentage of cells in the G1/G0 phase of the cell cycle. In contrast, RA did not alter the cell cycle distribution profile of RARbeta(2)(-/-) cells. In F9 Wt cells, cyclin D1, D3, and cyclin E protein levels decreased, while cyclin D2 and p27 levels increased after RA treatment. Compared to the F9 Wt cells, the F9 RARbeta(2)(-/-) cells exhibited lower levels of cyclins D1, D2, D3, and E in the absence of RA, but did not exhibit further changes in the levels of these cell cycle regulators after RA addition. Since RA significantly increased the level of p27 protein (approximately 24-fold) in F9 Wt as compared to the F9 RARbeta(2)(-/-) cells, we chose to study p27 in greater detail. The p27 mRNA level and the rate of p27 protein synthesis were increased in RA-treated F9 Wt cells, but not in F9 RARbeta(2)(-/-) cells. Moreover, RA increased the half-life of p27 protein in F9 Wt cells. Reduced expression of RARbeta(2) is associated with the process of carcinogenesis and RARbeta(2) can mediate the growth arrest induced by RA in a variety of cancer cells. Using both genetic and molecular approaches, we have identified some of the molecular mechanisms, such as the large elevation of p27, through which RARbeta(2) mediates these growth inhibitory effects of RA in F9 cells.
Collapse
Affiliation(s)
- Rong Li
- Department of Pharmacology, Weill Medical College of Cornell University, New York, NY 10021, USA
| | | | | | | | | |
Collapse
|
35
|
Smith ER, Smedberg JL, Rula ME, Xu XX. Regulation of Ras-MAPK pathway mitogenic activity by restricting nuclear entry of activated MAPK in endoderm differentiation of embryonic carcinoma and stem cells. ACTA ACUST UNITED AC 2004; 164:689-99. [PMID: 14981092 PMCID: PMC2172165 DOI: 10.1083/jcb.200312028] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In response to retinoic acid, embryonic stem and carcinoma cells undergo differentiation to embryonic primitive endoderm cells, accompanied by a reduction in cell proliferation. Differentiation does not reduce the activation of cellular MAPK/Erk, but does uncouple mitogen-activated protein kinase (MAPK) activation from phosphorylation/activation of Elk-1 and results in inhibition of c-Fos expression, whereas phosphorylation of the cytoplasmic substrate p90RSK remains unaltered. Cell fractionation and confocal immunofluorescence microscopy demonstrated that activated MAPK is restricted to the cytoplasmic compartment after differentiation. An intact actin and microtubule cytoskeleton appears to be required for the restriction of MAPK nuclear entry induced by retinoic acid treatment because the cytoskeletal disrupting agents nocodazole, colchicine, and cytochalasin D are able to revert the suppression of c-Fos expression. Thus, suppression of cell proliferation after retinoic acid–induced endoderm differentiation of embryonic stem and carcinoma cells is achieved by restricting nuclear entry of activated MAPK, and an intact cytoskeleton is required for the restraint.
Collapse
Affiliation(s)
- Elizabeth R Smith
- Ovarian Cancer and Tumor Cell Biology Programs, Dept. of Medical Oncology, Medical Science Division, Fox Chase Cancer Center, 7701 Burholme Ave., Philadelphia, PA 19111, USA
| | | | | | | |
Collapse
|
36
|
Rochette-Egly C. Nuclear receptors: integration of multiple signalling pathways through phosphorylation. Cell Signal 2003; 15:355-66. [PMID: 12618210 DOI: 10.1016/s0898-6568(02)00115-8] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Nuclear receptors (NRs) orchestrate the transcription of specific gene networks in response to binding of their cognate ligand. They also act as mediators in a variety of signalling pathways through integrating diverse phosphorylation events. NR phosphorylation concerns all three major domains, the N-terminal activation function (AF-1), the ligand-binding and the DNA binding domains. Often, phosphorylation of NRs by kinases that are associated with general transcription factors (e.g. cdk7 within TFIIH), or activated in response to a variety of signals (MAPKs, Akt, PKA, PKC), facilitates the recruitment of coactivators or of components of the transcription machinery and, therefore, cooperates with the ligand to enhance transcription activation. But phosphorylation can also contribute to the termination of the ligand response through inducing DNA dissociation or NR degradation or through decreasing ligand affinity. These different modes of regulation reveal an unexpected complexity of the dynamics of NR-mediated transcription. In addition, deregulation of NR phosphorylation may impact their action in certain diseases or cancers.
Collapse
Affiliation(s)
- Cécile Rochette-Egly
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, UMR 7104 1 rue Laurent Fries, BP 163, 67404 Illkirch Cedex, France.
| |
Collapse
|