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Kakiyama G, Rodriguez-Agudo D, Pandak WM. Mitochondrial Cholesterol Metabolites in a Bile Acid Synthetic Pathway Drive Nonalcoholic Fatty Liver Disease: A Revised "Two-Hit" Hypothesis. Cells 2023; 12:1434. [PMID: 37408268 PMCID: PMC10217489 DOI: 10.3390/cells12101434] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 05/15/2023] [Accepted: 05/17/2023] [Indexed: 07/07/2023] Open
Abstract
The rising prevalence of nonalcoholic fatty liver disease (NAFLD)-related cirrhosis highlights the need for a better understanding of the molecular mechanisms responsible for driving the transition of hepatic steatosis (fatty liver; NAFL) to steatohepatitis (NASH) and fibrosis/cirrhosis. Obesity-related insulin resistance (IR) is a well-known hallmark of early NAFLD progression, yet the mechanism linking aberrant insulin signaling to hepatocyte inflammation has remained unclear. Recently, as a function of more distinctly defining the regulation of mechanistic pathways, hepatocyte toxicity as mediated by hepatic free cholesterol and its metabolites has emerged as fundamental to the subsequent necroinflammation/fibrosis characteristics of NASH. More specifically, aberrant hepatocyte insulin signaling, as found with IR, leads to dysregulation in bile acid biosynthetic pathways with the subsequent intracellular accumulation of mitochondrial CYP27A1-derived cholesterol metabolites, (25R)26-hydroxycholesterol and 3β-Hydroxy-5-cholesten-(25R)26-oic acid, which appear to be responsible for driving hepatocyte toxicity. These findings bring forth a "two-hit" interpretation as to how NAFL progresses to NAFLD: abnormal hepatocyte insulin signaling, as occurs with IR, develops as a "first hit" that sequentially drives the accumulation of toxic CYP27A1-driven cholesterol metabolites as the "second hit". In the following review, we examine the mechanistic pathway by which mitochondria-derived cholesterol metabolites drive the development of NASH. Insights into mechanistic approaches for effective NASH intervention are provided.
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Affiliation(s)
- Genta Kakiyama
- Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA; (D.R.-A.); (W.M.P.)
- Research Services, Central Virginia Veterans Affairs Healthcare System, Richmond, VA 23249, USA
| | - Daniel Rodriguez-Agudo
- Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA; (D.R.-A.); (W.M.P.)
- Research Services, Central Virginia Veterans Affairs Healthcare System, Richmond, VA 23249, USA
| | - William M. Pandak
- Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA; (D.R.-A.); (W.M.P.)
- Research Services, Central Virginia Veterans Affairs Healthcare System, Richmond, VA 23249, USA
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2
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Kakiyama G, Marques D, Martin R, Takei H, Rodriguez-Agudo D, LaSalle SA, Hashiguchi T, Liu X, Green R, Erickson S, Gil G, Fuchs M, Suzuki M, Murai T, Nittono H, Hylemon PB, Zhou H, Pandak WM. Insulin resistance dysregulates CYP7B1 leading to oxysterol accumulation: a pathway for NAFL to NASH transition. J Lipid Res 2020; 61:1629-1644. [PMID: 33008924 PMCID: PMC7707165 DOI: 10.1194/jlr.ra120000924] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
NAFLD is an important public health issue closely associated with the pervasive epidemics of diabetes and obesity. Yet, despite NAFLD being among the most common of chronic liver diseases, the biological factors responsible for its transition from benign nonalcoholic fatty liver (NAFL) to NASH remain unclear. This lack of knowledge leads to a decreased ability to find relevant animal models, predict disease progression, or develop clinical treatments. In the current study, we used multiple mouse models of NAFLD, human correlation data, and selective gene overexpression of steroidogenic acute regulatory protein (StarD1) in mice to elucidate a plausible mechanistic pathway for promoting the transition from NAFL to NASH. We show that oxysterol 7α-hydroxylase (CYP7B1) controls the levels of intracellular regulatory oxysterols generated by the "acidic/alternative" pathway of cholesterol metabolism. Specifically, we report data showing that an inability to upregulate CYP7B1, in the setting of insulin resistance, results in the accumulation of toxic intracellular cholesterol metabolites that promote inflammation and hepatocyte injury. This metabolic pathway, initiated and exacerbated by insulin resistance, offers insight into approaches for the treatment of NAFLD.
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Affiliation(s)
- Genta Kakiyama
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, USA; Department of Veterans Affairs, McGuire Veterans Administration Medical Center, Richmond, VA, USA.
| | - Dalila Marques
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, USA; Department of Veterans Affairs, McGuire Veterans Administration Medical Center, Richmond, VA, USA
| | - Rebecca Martin
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA
| | - Hajime Takei
- Junshin Clinic Bile Acid Institute, Tokyo, Japan
| | - Daniel Rodriguez-Agudo
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, USA; Department of Veterans Affairs, McGuire Veterans Administration Medical Center, Richmond, VA, USA
| | - Sandra A LaSalle
- Department of Veterans Affairs, McGuire Veterans Administration Medical Center, Richmond, VA, USA
| | | | - Xiaoying Liu
- Department of Medicine, Northwestern University, Chicago, IL, USA
| | - Richard Green
- Department of Medicine, Northwestern University, Chicago, IL, USA
| | - Sandra Erickson
- School of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Gregorio Gil
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA, USA; Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA
| | - Michael Fuchs
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, USA; Department of Veterans Affairs, McGuire Veterans Administration Medical Center, Richmond, VA, USA
| | - Mitsuyoshi Suzuki
- Department of Pediatrics, Juntendo University Faculty of Medicine, Tokyo, Japan
| | - Tsuyoshi Murai
- School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Hokkaido, Japan
| | | | - Phillip B Hylemon
- Department of Veterans Affairs, McGuire Veterans Administration Medical Center, Richmond, VA, USA; Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA; Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA
| | - Huiping Zhou
- Department of Veterans Affairs, McGuire Veterans Administration Medical Center, Richmond, VA, USA; Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA; Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA
| | - William M Pandak
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, USA; Department of Veterans Affairs, McGuire Veterans Administration Medical Center, Richmond, VA, USA; Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA
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Yang C, Yu W, Bi Y, Long F, Li Y, Wei D, Hao X, Situ J, Zhao Y, Huang F. Increased oestradiol in hepatitis E virus-infected pregnant women promotes viral replication. J Viral Hepat 2018; 25:742-751. [PMID: 29345855 DOI: 10.1111/jvh.12865] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 12/14/2017] [Indexed: 01/17/2023]
Abstract
Hepatitis E virus (HEV) infection causes subclinical diseases, leading to high mortality (>25%) in pregnant women. HEV replication is aggressively escalated in pregnant women, especially in the third trimester of pregnancy. Oestrogen plays an important role in pregnancy. However, the pathogenesis of HEV in pregnant women or immunosuppressive pregnant women (such as HIV-infected or organ-transplanted pregnant women) remains unclear. We investigated the role of oestradiol in HEV infection in a cell culture system. HEV-infected pregnant women had significantly higher oestradiol levels compared with uninfected individuals. HEV infection was significantly increased in cells treated with analogues of oestradiol, diethylstilbestrol (DES) or 17β-oestradiol in a dose-dependent way. However, tamoxifen, an antagonist oestrogen, inhibited HEV replication. HEV infection inhibits oestrogen receptor (ER-α) expression. Immunofluorescence and co-immunoprecipitation assays indicated that ER-α interacted with the helicase of HEV ORF1 indirectly. More importantly, HEV infection was exacerbated in immunosuppressive cells treated with an inhibitor of PI3K-AKT-mTOR signal pathway (LY296004) and supplemented with pregnant women serum with high oestradiol simultaneously. These results strongly suggest that pregnant women with high oestradiol and/or immunosuppression will be vulnerable to HEV infection.
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Affiliation(s)
- C Yang
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - W Yu
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, China
| | - Y Bi
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - F Long
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - Y Li
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - D Wei
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - X Hao
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - J Situ
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - Y Zhao
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - F Huang
- Medical School, Kunming University of Science and Technology, Kunming, China
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Juszczak GR, Stankiewicz AM. Glucocorticoids, genes and brain function. Prog Neuropsychopharmacol Biol Psychiatry 2018; 82:136-168. [PMID: 29180230 DOI: 10.1016/j.pnpbp.2017.11.020] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/18/2017] [Accepted: 11/23/2017] [Indexed: 01/02/2023]
Abstract
The identification of key genes in transcriptomic data constitutes a huge challenge. Our review of microarray reports revealed 88 genes whose transcription is consistently regulated by glucocorticoids (GCs), such as cortisol, corticosterone and dexamethasone, in the brain. Replicable transcriptomic data were combined with biochemical and physiological data to create an integrated view of the effects induced by GCs. The most frequently reported genes were Errfi1 and Ddit4. Their up-regulation was associated with the altered transcription of genes regulating growth factor and mTORC1 signaling (Gab1, Tsc22d3, Dusp1, Ndrg2, Ppp5c and Sesn1) and progression of the cell cycle (Ccnd1, Cdkn1a and Cables1). The GC-induced reprogramming of cell function involves changes in the mRNA level of genes responsible for the regulation of transcription (Klf9, Bcl6, Klf15, Tle3, Cxxc5, Litaf, Tle4, Jun, Sox4, Sox2, Sox9, Irf1, Sall2, Nfkbia and Id1) and the selective degradation of mRNA (Tob2). Other genes are involved in the regulation of metabolism (Gpd1, Aldoc and Pdk4), actin cytoskeleton (Myh2, Nedd9, Mical2, Rhou, Arl4d, Osbpl3, Arhgef3, Sdc4, Rdx, Wipf3, Chst1 and Hepacam), autophagy (Eva1a and Plekhf1), vesicular transport (Rhob, Ehd3, Vps37b and Scamp2), gap junctions (Gjb6), immune response (Tiparp, Mertk, Lyve1 and Il6r), signaling mediated by thyroid hormones (Thra and Sult1a1), calcium (Calm2), adrenaline/noradrenaline (Adcy9 and Adra1d), neuropeptide Y (Npy1r) and histamine (Hdc). GCs also affected genes involved in the synthesis of polyamines (Azin1) and taurine (Cdo1). The actions of GCs are restrained by feedback mechanisms depending on the transcription of Sgk1, Fkbp5 and Nr3c1. A side effect induced by GCs is increased production of reactive oxygen species. Available data show that the brain's response to GCs is part of an emergency mode characterized by inactivation of non-core activities, restrained inflammation, restriction of investments (growth), improved efficiency of energy production and the removal of unnecessary or malfunctioning cellular components to conserve energy and maintain nutrient supply during the stress response.
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Affiliation(s)
- Grzegorz R Juszczak
- Department of Animal Behavior, Institute of Genetics and Animal Breeding, Jastrzebiec, ul. Postepu 36A, 05-552 Magdalenka, Poland.
| | - Adrian M Stankiewicz
- Department of Molecular Biology, Institute of Genetics and Animal Breeding, Jastrzebiec, ul. Postepu 36A, 05-552 Magdalenka, Poland
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Song Z, Shi Q. The Interaction of PPARα and CYP7B1 with ERα, β Impacted the Occurrence and Development of Intrahepatic Cholestasis in Pregnant Rats. Reprod Sci 2016; 24:627-634. [PMID: 27628953 DOI: 10.1177/1933719116667223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Intrahepatic cholestasis of pregnancy (ICP) is a disorder of bile acid (BA) synthesis, excretion, and metabolism, with systemic accumulation of BAs, which can lead to prematurity, fetal distress, and intrauterine death. Here, we investigate the expression of peroxisome proliferator-activated receptor alpha and cytochrome P450 oxysterol 7alpha-hydroxylase by exposing to 17α-ethynylestradiol with or without the estrogen receptor signaling pathway in pregnant rats with intrahepatic cholestasis. In vivo and in vitro evidences showed that estrogen receptor alpha (ERα) may be the key point of occurrence and development of intrahepatic cholestasis in pregnant rats. Besides, the abnormalities in genes could be reversed by ERα small interfering RNA. Our findings provide the ERα-centered hypothesis on the mechanisms of ICP. New perspectives are emerging for the treatment of estrogen-induced hepatic complication.
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Affiliation(s)
- Zhaoyi Song
- 1 Department of Obstetrics and Gynecology, Ninth School of Clinical Medicine, Peking University, Beijing, China
| | - Qingyun Shi
- 2 Department of Obstetrics and Gynecology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
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Umetani M. Re-adopting classical nuclear receptors by cholesterol metabolites. J Steroid Biochem Mol Biol 2016; 157:20-6. [PMID: 26563834 PMCID: PMC4724260 DOI: 10.1016/j.jsbmb.2015.11.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 07/10/2015] [Accepted: 11/04/2015] [Indexed: 12/22/2022]
Abstract
Since the first cloning of the human estrogen receptor (ER) α in 1986 and the subsequent cloning of human ERβ, there has been extensive investigation of the role of estrogen/ER. Estrogens/ER play important roles not only in sexual development and reproduction but also in a variety of other functions in multiple tissues. Selective Estrogen Receptor Modulators (SERMs) are ER lignds that act as agonists or antagonists depending on the target genes and tissues, and until recently, only synthetic SERMs have been recognized. However, the discovery of the first endogenous SERM, 27-hydroxycholesterol (27HC), opened a new dimension of ER action in health and disease. In addition to the identification of 27HC as a SERM, oxysterols have been recently demonstrated as indirect modulators of ER through interaction with the nuclear receptor Liver X Receptor (LXR) β. In this review, the recent progress on these novel roles of oxysterols in ER modulation is summarized.
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Affiliation(s)
- Michihisa Umetani
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, 3517 Cullen Blvd, SERC 545, Houston, TX 77204-5056, USA.
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Lee WR, Ishikawa T, Umetani M. The interaction between metabolism, cancer and cardiovascular disease, connected by 27-hydroxycholesterol. ACTA ACUST UNITED AC 2014; 9:617-624. [PMID: 25632306 DOI: 10.2217/clp.14.53] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Oxysterols are metabolites of cholesterol that are produced in liver and other peripheral tissues as a means to eliminate cholesterol to bile acid. Recent studies have revealed that the most abundant circulating oxysterol 27-hydroxycholesterol (27HC) is the first identified endogenous selective estrogen receptor modulator. 27HC levels correlate well with that of cholesterol, and also rise progressively with age. 27HC affects estrogen receptor function by the antagonism of estrogen action and also by the direct modulation of the receptor function, and similar to estrogen/estrogen receptors, 27HC has many actions in various tissues. This review article introduces the recent progress in the understanding of the role of 27HC in breast cancer and cardiovascular dysfunction.
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Affiliation(s)
- Wan-Ru Lee
- Division of Pulmonary & Vascular Biology, Departments of Pediatrics & Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA
| | - Tomonori Ishikawa
- Division of Pulmonary & Vascular Biology, Departments of Pediatrics & Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA ; Comprehensive Reproductive Medicine, Graduate School of Medical & Dental Sciences, Tokyo Medical & Dental University, Tokyo, Japan
| | - Michihisa Umetani
- Division of Pulmonary & Vascular Biology, Departments of Pediatrics & Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA
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Slominski AT, Zmijewski MA, Semak I, Zbytek B, Pisarchik A, Li W, Zjawiony J, Tuckey RC. Cytochromes p450 and skin cancer: role of local endocrine pathways. Anticancer Agents Med Chem 2014; 14:77-96. [PMID: 23869782 DOI: 10.2174/18715206113139990308] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 01/30/2013] [Accepted: 04/10/2013] [Indexed: 12/19/2022]
Abstract
Skin is the largest body organ forming a metabolically active barrier between external and internal environments. The metabolic barrier is composed of cytochromes P450 (CYPs) that regulate its homeostasis through activation or inactivation of biologically relevant molecules. In this review we focus our attention on local steroidogenic and secosteroidogenic systems in relation to skin cancer, e.g., prevention, attenuation of tumor progression and therapy. The local steroidogenic system is composed of locally expressed CYPs involved in local production of androgens, estrogens, gluco- and mineralo-corticosteroids from cholesterol (initiated by CYP11A1) or from steroid precursors delivered to the skin, and of their metabolism and/or inactivation. Cutaneous 7-hydroxylases (CYP7A1, CYP7B1 and CYP39) potentially can produce 7-hydroxy/oxy-steroids/sterols with modifying effects on local tumorigenesis. CYP11A1 also transforms 7-dehydrocholesterol (7DHC)→22(OH)7DHC→20,22(OH)2-7DHC→7-dehydropregnenolone, which can be further metabolized to other 5,7- steroidal dienes. These 5,7-dienal intermediates are converted by ultraviolet radiation B (UVB) into secosteroids which show pro-differentiation and anti-cancer properties. Finally, the skin is the site of activation of vitamin D3 through two alternative pathways. The classical one involves sequential hydroxylation at positions 25 and 1 to produce active 1,25(OH)2D3, which is further inactivated through hydroxylation at C24. The novel pathway is initiated by CYP11A1 with predominant production of 20(OH)D3 which is further metabolized to biologically active but non-calcemic D3-hydroxyderivatives. Classical and non-classical (novel) vitamin D analogs show pro-differentiation, anti-proliferative and anticancer properties. In addition, melatonin is metabolized by local CYPs. In conclusion cutaneously expressed CYPs have significant effects on skin physiology and pathology trough regulation of its chemical milieu.
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Affiliation(s)
| | | | | | | | | | | | | | - Robert C Tuckey
- Department of Pathology and Laboratory Medicine, University of Tennessee Health Science Center, 930 Madison Avenue, RM525, Memphis, TN 38163, USA.
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27-Hydroxycholesterol promotes cell-autonomous, ER-positive breast cancer growth. Cell Rep 2013; 5:637-45. [PMID: 24210818 DOI: 10.1016/j.celrep.2013.10.006] [Citation(s) in RCA: 262] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/11/2013] [Accepted: 10/02/2013] [Indexed: 01/10/2023] Open
Abstract
To date, estrogen is the only known endogenous estrogen receptor (ER) ligand that promotes ER+ breast tumor growth. We report that the cholesterol metabolite 27-hydroxycholesterol (27HC) stimulates MCF-7 cell xenograft growth in mice. More importantly, in ER+ breast cancer patients, 27HC content in normal breast tissue is increased compared to that in cancer-free controls, and tumor 27HC content is further elevated. Increased tumor 27HC is correlated with diminished expression of CYP7B1, the 27HC metabolizing enzyme, and reduced expression of CYP7B1 in tumors is associated with poorer patient survival. Moreover, 27HC is produced by MCF-7 cells, and it stimulates cell-autonomous, ER-dependent, and GDNF-RET-dependent cell proliferation. Thus, 27HC is a locally modulated, nonaromatized ER ligand that promotes ER+ breast tumor growth.
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Wancket LM, Meng X, Rogers LK, Liu Y. Mitogen-activated protein kinase phosphatase (Mkp)-1 protects mice against acetaminophen-induced hepatic injury. Toxicol Pathol 2012; 40:1095-105. [PMID: 22623522 DOI: 10.1177/0192623312447551] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
c-Jun N-terminal kinase (JNK) activation promotes hepatocyte death during acetaminophen overdose, a common cause of drug-induced liver failure. While mitogen-activated protein kinase (MAPK) phosphatase (Mkp)-1 is a critical negative regulator of JNK MAPK, little is known about the role of Mkp-1 during hepatotoxicity. In this study, we evaluated the role of Mkp-1 during acute acetaminophen toxicity. Mkp-1⁺/⁺ and Mkp-1⁻/⁻ mice were dosed ip with vehicle or acetaminophen at 300 mg/kg (for mechanistic studies) or 400 mg/kg (for survival studies). Tissues were collected 1-6 hr post 300 mg/kg dosing to assess glutathione levels, organ damage, and MAPK activation. Mkp-1⁻/⁻ mice exhibited more rapid plasma clearance of acetaminophen than did Mkp-1⁺/⁺ mice, indicated by a quicker decline of plasma acetaminophen level. Moreover, Mkp-1⁻/⁻ mice suffered more severe liver injury, indicated by higher plasma alanine transaminase activity and more extensive centrilobular apoptosis and necrosis. Hepatic JNK activity in Mkp-1⁻/⁻ mice was higher than in Mkp-1⁺/⁺ mice. Finally, Mkp-1⁻/⁻ mice displayed a lower overall survival rate and shorter median survival time after dosing with 400 mg/kg acetaminophen. The more severe phenotype exhibited by Mkp-1⁻/⁻ mice indicates that Mkp-1 plays a protective role during acute acetaminophen overdose, potentially through regulation of JNK.
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Affiliation(s)
- Lyn M Wancket
- Department of Veterinary Bioscience, The Ohio State University College of Veterinary Medicine, Columbus, Ohio, USA
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Fex Svenningsen A, Wicher G, Lundqvist J, Pettersson H, Corell M, Norlin M. Effects on DHEA levels by estrogen in rat astrocytes and CNS co-cultures via the regulation of CYP7B1-mediated metabolism. Neurochem Int 2011; 58:620-4. [PMID: 21300119 DOI: 10.1016/j.neuint.2011.01.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 12/17/2010] [Accepted: 01/20/2011] [Indexed: 11/29/2022]
Abstract
The neurosteroid dehydroepiandrosterone (DHEA) is formed locally in the CNS and has been implicated in several processes essential for CNS function, including control of neuronal survival. An important metabolic pathway for DHEA in the CNS involves the steroid hydroxylase CYP7B1. In previous studies, CYP7B1 was identified as a target for estrogen regulation in cells of kidney and liver. In the current study, we examined effects of estrogens on CYP7B1-mediated metabolism of DHEA in primary cultures of rat astrocytes and co-cultures of rat CNS cells. Astrocytes, which interact with neurons in several ways, are important for brain neurosteroidogenesis. We found that estradiol significantly suppressed CYP7B1-mediated DHEA hydroxylation in primary mixed CNS cultures from fetal and newborn rats. Also, CYP7B1-mediated DHEA hydroxylation and CYP7B1 mRNA were markedly suppressed by estrogen in primary cultures of rat astrocytes. Interestingly, diarylpropionitrile, a well-known agonist of estrogen receptor β, also suppressed CYP7B1-mediated hydroxylation of DHEA. Several previous studies have reported neuroprotective effects of estrogens. The current data indicate that one of the mechanisms whereby estrogen can exert protective effects in the CNS may involve increase of the levels of DHEA by suppression of its metabolism.
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Norlin M, Pettersson H, Tang W, Wikvall K. Androgen receptor-mediated regulation of the anti-atherogenic enzyme CYP27A1 involves the JNK/c-jun pathway. Arch Biochem Biophys 2011; 506:236-41. [DOI: 10.1016/j.abb.2010.11.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 11/30/2010] [Indexed: 12/16/2022]
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