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Crumbley C, Cepni AB, Taylor A, Thompson D, Moran NE, Olvera N, O'Connor DP, Johnston CA, Ledoux TA. Exploring Factors Associated With Accelerometer Validity Among Ethnically Diverse Toddlers. Pediatr Exerc Sci 2024; 36:66-74. [PMID: 37758263 DOI: 10.1123/pes.2022-0114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 05/11/2023] [Accepted: 07/28/2023] [Indexed: 10/03/2023]
Abstract
PURPOSE Studying physical activity in toddlers using accelerometers is challenging due to noncompliance with wear time (WT) and activity log (AL) instructions. The aims of this study are to examine relationships between WT and AL completion and (1) demographic and socioeconomic variables, (2) parenting style, and (3) whether sedentary time differs by AL completion. METHODS Secondary analysis was performed using baseline data from a community wellness program randomized controlled trial for parents with toddlers (12-35 mo). Parents had toddlers wear ActiGraph wGT3x accelerometers and completed ALs. Valid days included ≥600-minute WT. Analysis of variance and chi-square analyses were used. RESULTS The sample (n = 50) comprised racial and ethnically diverse toddlers (mean age = 27 mo, 58% male) and parents (mean age = 31.7 y, 84% female). Twenty-eight families (56%) returned valid accelerometer data with ALs. Participants in relationships were more likely to complete ALs (P < .05). Toddler sedentary time did not differ between those with ALs and those without. CONCLUSIONS We found varied compliance with WT instructions and AL completion. Returned AL quality was poor, presenting challenges in correctly characterizing low-activity counts to improve internal validity of WT and physical activity measures. Support from marital partners may be important for adherence to study protocols.
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Affiliation(s)
- Christine Crumbley
- Department of Health and Human Performance, University of Houston, Houston, TX,USA
| | - Aliye B Cepni
- Department of Health and Human Performance, University of Houston, Houston, TX,USA
| | - Ashley Taylor
- Department of Psychological, Health, and Learning Sciences, University of Houston, Houston, TX,USA
| | - Debbe Thompson
- USDA/ARS Children's Nutrition Research Center & Department of Pediatrics, Baylor College of Medicine, Houston, TX,USA
| | - Nancy E Moran
- USDA/ARS Children's Nutrition Research Center & Department of Pediatrics, Baylor College of Medicine, Houston, TX,USA
| | - Norma Olvera
- Department of Psychological, Health, and Learning Sciences, University of Houston, Houston, TX,USA
- Latino Health Disparities Lab, University of Houston, Houston, TX,USA
| | - Daniel P O'Connor
- Department of Health and Human Performance, University of Houston, Houston, TX,USA
- HEALTH Research Institute, University of Houston, Houston, TX,USA
| | - Craig A Johnston
- Department of Health and Human Performance, University of Houston, Houston, TX,USA
| | - Tracey A Ledoux
- Department of Health and Human Performance, University of Houston, Houston, TX,USA
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Abstract
Despite considerable evidence that plant-based diets can significantly improve health, medical professionals seldom discuss this with their patients. This issue might occur due to minimal training received in medical education, lack of time, and low self-efficacy for counseling patients about diet. Nutrition and lifestyle change should be considered a core competency for all physicians and health professionals looking for cost-effective ways to improve patient health outcomes and reduce nutrition-related chronic diseases. Strategies for health professionals to acquire nutrition counseling skills in medical training and clinical practices are discussed.
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Affiliation(s)
- Aliye B. Cepni
- Department of Health and Human Performance, University of Houston, Houston, TX, USA
| | - Christine Crumbley
- Department of Health and Human Performance, University of Houston, Houston, TX, USA
| | - Saad Nadeem
- Department of Health and Human Performance, University of Houston, Houston, TX, USA
| | - Tracey A. Ledoux
- Department of Health and Human Performance, University of Houston, Houston, TX, USA
| | - Craig A. Johnston
- Department of Health and Human Performance, University of Houston, Houston, TX, USA
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3
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Cepni AB, Taylor A, Crumbley C, Thompson D, Moran NE, Olvera N, O’Connor DP, Arlinghaus KR, Johnston CA, Ledoux TA. Feasibility and Efficacy of the "FUNPALs Playgroup" Intervention to Improve Toddler Dietary and Activity Behaviors: A Pilot Randomized Controlled Trial. Int J Environ Res Public Health 2021; 18:ijerph18157828. [PMID: 34360118 PMCID: PMC8345510 DOI: 10.3390/ijerph18157828] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/14/2021] [Accepted: 07/20/2021] [Indexed: 11/16/2022]
Abstract
This study evaluated the feasibility and effects of the Families Understanding Nutrition and Physically Active Lifestyles (FUNPALs) Playgroup on toddler (12–36-month-old) diet and activity behaviors. Parent–toddler dyads were recruited from disadvantaged communities and randomly assigned to receive 10-weekly sessions of the FUNPALs Playgroup (n = 24) or dose-matched health education control group (n = 26). FUNPALs Playgroups involved physical and snack activities, delivery of health information, and positive parenting coaching. The control group involved group health education for parents only. Process outcomes (e.g., retention rate, fidelity) and focus groups determined feasibility and perceived effects. To evaluate preliminary effects, validated measures of toddler diet (food frequency questionnaire and a carotenoid biomarker), physical activity (PA; accelerometers), general and feeding parenting (self-report surveys), and home environment (phone interview) were collected pre and post. The sample comprised parents (84% female) who self-identified as Hispanic/Latino (38%) and/or African American (32%). Retention was high (78%). Parents from both groups enjoyed the program and perceived improvements in their children’s health behaviors. Objective measures demonstrated improvement with large effects (η2 = 0.29) in toddler diet (p < 0.001) but not PA (p = 0.099). In conclusion, the FUNPALs Playgroup is feasible and may improve toddler eating behaviors.
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Affiliation(s)
- Aliye B. Cepni
- Department of Health and Human Performance, University of Houston, Houston, TX 77204, USA; (A.B.C.); (C.C.); (D.P.O.); (C.A.J.)
| | - Ashley Taylor
- Department of Psychological, Health and Learning Sciences, University of Houston, Houston, TX 77204, USA;
| | - Christine Crumbley
- Department of Health and Human Performance, University of Houston, Houston, TX 77204, USA; (A.B.C.); (C.C.); (D.P.O.); (C.A.J.)
| | - Debbe Thompson
- USDA/ARS Children’s Nutrition Research Center and Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA; (D.T.); (N.E.M.)
| | - Nancy E. Moran
- USDA/ARS Children’s Nutrition Research Center and Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA; (D.T.); (N.E.M.)
| | - Norma Olvera
- Department of Psychological, Latino Health Disparities Lab, University of Houston, Houston, TX 77204, USA;
| | - Daniel P. O’Connor
- Department of Health and Human Performance, University of Houston, Houston, TX 77204, USA; (A.B.C.); (C.C.); (D.P.O.); (C.A.J.)
| | - Katherine R. Arlinghaus
- Division of Epidemiology and Community Health, University of Minnesota School of Public Health, Minneapolis, MN 55455, USA;
| | - Craig A. Johnston
- Department of Health and Human Performance, University of Houston, Houston, TX 77204, USA; (A.B.C.); (C.C.); (D.P.O.); (C.A.J.)
| | - Tracey A. Ledoux
- Department of Health and Human Performance, University of Houston, Houston, TX 77204, USA; (A.B.C.); (C.C.); (D.P.O.); (C.A.J.)
- Correspondence: ; Tel.: +1-713-743-1870
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Ledoux T, Cepni A, Taylor A, Crumbley C, Thompson D, Moran N, Olvera N, O'Connor D. Exploring Parent Feeding Practices, the Home Environment, and Toddler Diet. J Acad Nutr Diet 2020. [DOI: 10.1016/j.jand.2020.06.071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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5
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Hiramitsu S, Ishikawa T, Lee WR, Khan T, Crumbley C, Khwaja N, Zamanian F, Asghari A, Sen M, Zhang Y, Hawse JR, Minna JD, Umetani M. Estrogen Receptor Beta-Mediated Modulation of Lung Cancer Cell Proliferation by 27-Hydroxycholesterol. Front Endocrinol (Lausanne) 2018; 9:470. [PMID: 30190703 PMCID: PMC6116707 DOI: 10.3389/fendo.2018.00470] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 07/30/2018] [Indexed: 12/27/2022] Open
Abstract
27-hydroxycholesterol (27HC) is an abundant cholesterol metabolite in human circulation and promotes breast cancer cell proliferation. Although lung is one of the organs that contain high levels of 27HC, the role of 27HC in lung is unknown. In this study, we found that 27HC promotes lung cancer cell proliferation in an estrogen receptor β (ERβ)-dependent manner. The expression of 27HC-generating enzyme CYP27A1 is higher in lung cancer cells than in normal lung cells. Treatment with 27HC increased cell proliferation in ERβ-positive lung cancer cells, but not in ERα-positive or ER-negative cells. The effect on cell proliferation is specific to 27HC and another oxysterol, 25-hydroxycholesterol that has a similar oxysterol structure with 27HC. Moreover, among ligands for nuclear receptors tested, only estrogen had the proliferative effect, and the effect by 27HC and estrogen was inhibited by ERβ-specific, but not ERα-specific, inhibitors. In addition, the effect by 27HC was not affected by membrane-bound estrogen receptor GPR30. Interestingly, despite the high expression of CYP27A1, endogenously produced 27HC was not the major contributor of the 27HC-induced cell proliferation. Using kinase inhibitors, we found that the effect by 27HC was mediated by the PI3K-Akt signaling pathway. These results suggest that 27HC promotes lung cancer cell proliferation via ERβ and PI3K-Akt signaling. Thus, lowering 27HC levels may lead to a novel approach for the treatment of lung cancer.
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Affiliation(s)
- Shiro Hiramitsu
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, United States
- Department of Biology and Biochemistry, College of Natural Sciences and Mathematics, University of Houston, Houston, TX, United States
| | - Tomonori Ishikawa
- Division of Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Wan-Ru Lee
- Division of Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Tamor Khan
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, United States
- Department of Biology and Biochemistry, College of Natural Sciences and Mathematics, University of Houston, Houston, TX, United States
| | - Christine Crumbley
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, United States
- Department of Biology and Biochemistry, College of Natural Sciences and Mathematics, University of Houston, Houston, TX, United States
| | - Nimra Khwaja
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, United States
- Department of Biology and Biochemistry, College of Natural Sciences and Mathematics, University of Houston, Houston, TX, United States
| | - Faezeh Zamanian
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, United States
- Department of Biology and Biochemistry, College of Natural Sciences and Mathematics, University of Houston, Houston, TX, United States
| | - Arvand Asghari
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, United States
- Department of Biology and Biochemistry, College of Natural Sciences and Mathematics, University of Houston, Houston, TX, United States
| | - Mehmet Sen
- Department of Biology and Biochemistry, College of Natural Sciences and Mathematics, University of Houston, Houston, TX, United States
| | - Yang Zhang
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX, United States
| | - John R. Hawse
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, United States
| | - John D. Minna
- Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Michihisa Umetani
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, United States
- Department of Biology and Biochemistry, College of Natural Sciences and Mathematics, University of Houston, Houston, TX, United States
- *Correspondence: Michihisa Umetani
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Burris TP, Solt LA, Wang Y, Crumbley C, Banerjee S, Griffett K, Lundasen T, Hughes T, Kojetin DJ. Nuclear receptors and their selective pharmacologic modulators. Pharmacol Rev 2013; 65:710-78. [PMID: 23457206 PMCID: PMC11060414 DOI: 10.1124/pr.112.006833] [Citation(s) in RCA: 180] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Nuclear receptors are ligand-activated transcription factors and include the receptors for steroid hormones, lipophilic vitamins, sterols, and bile acids. These receptors serve as targets for development of myriad drugs that target a range of disorders. Classically defined ligands that bind to the ligand-binding domain of nuclear receptors, whether they are endogenous or synthetic, either activate receptor activity (agonists) or block activation (antagonists) and due to the ability to alter activity of the receptors are often termed receptor "modulators." The complex pharmacology of nuclear receptors has provided a class of ligands distinct from these simple modulators where ligands display agonist/partial agonist/antagonist function in a tissue or gene selective manner. This class of ligands is defined as selective modulators. Here, we review the development and pharmacology of a range of selective nuclear receptor modulators.
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Affiliation(s)
- Thomas P Burris
- The Scripps Research Institute, 130 Scripps Way 2A1, Jupiter, FL 33458, USA.
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Crumbley C, Wang Y, Banerjee S, Burris TP. Regulation of expression of citrate synthase by the retinoic acid receptor-related orphan receptor α (RORα). PLoS One 2012; 7:e33804. [PMID: 22485150 PMCID: PMC3317774 DOI: 10.1371/journal.pone.0033804] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 02/22/2012] [Indexed: 11/19/2022] Open
Abstract
The retinoic acid receptor-related orphan receptor α (RORα) is a member of the nuclear receptor superfamily of transcription factors that plays an important role in regulation of the circadian rhythm and metabolism. Mice lacking a functional RORα display a range of metabolic abnormalities including decreased serum cholesterol and plasma triglycerides. Citrate synthase (CS) is a key enzyme of the citric acid cycle that provides energy for cellular function. Additionally, CS plays a critical role in providing citrate derived acetyl-CoA for lipogenesis and cholesterologenesis. Here, we identified a functional RORα response element (RORE) in the promoter of the CS gene. ChIP analysis demonstrates RORα occupancy of the CS promoter and a putative RORE binds to RORα effectively in an electrophoretic mobility shift assay and confers RORα responsiveness to a reporter gene in a cotransfection assay. We also observed a decrease in CS gene expression and CS enzymatic activity in the staggerer mouse, which has a mutation of in the Rora gene resulting in nonfunctional RORα protein. Furthermore, we found that SR1001 a RORα inverse agonist eliminated the circadian pattern of expression of CS mRNA in mice. These data suggest that CS is a direct RORα target gene and one mechanism by which RORα regulates lipid metabolism is via regulation of CS expression.
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Affiliation(s)
- Christine Crumbley
- Department of Molecular Therapeutics and Center for Diabetes and Metabolic Disease, The Scripps Research Institute, Jupiter, Florida, United States of America
| | - Yongjun Wang
- Department of Molecular Therapeutics and Center for Diabetes and Metabolic Disease, The Scripps Research Institute, Jupiter, Florida, United States of America
| | - Subhashis Banerjee
- Department of Molecular Therapeutics and Center for Diabetes and Metabolic Disease, The Scripps Research Institute, Jupiter, Florida, United States of America
| | - Thomas P. Burris
- Department of Molecular Therapeutics and Center for Diabetes and Metabolic Disease, The Scripps Research Institute, Jupiter, Florida, United States of America
- * E-mail:
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8
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Abstract
Circadian rhythms are regulated at the cellular level by transcriptional feedback loops leading to oscillations in expression of key proteins including CLOCK, BMAL1, PERIOD (PER), and CRYPTOCHROME (CRY). The CLOCK and BMAL1 proteins are members of the bHLH class of transcription factors and form a heterodimer that regulates the expression of the PER and CRY genes. The nuclear receptor REV-ERBα plays a key role in regulation of oscillations in BMAL1 expression by directly binding to the BMAL1 promoter and suppressing its expression at certain times of day when REV-ERBα expression levels are elevated. We recently demonstrated that REV-ERBα also regulates the expression of NPAS2, a heterodimer partner of BMAL1. Here, we show that REV-ERBα also regulates the expression another heterodimer partner of BMAL1, CLOCK. We identified a REV-ERBα binding site within the 1st intron of the CLOCK gene using a chromatin immunoprecipitation – microarray screen. Suppression of REV-ERBα expression resulted in elevated CLOCK mRNA expression consistent with REV-ERBα's role as a transcriptional repressor. A REV-ERB response element (RevRE) was identified within this region of the CLOCK gene and was conserved between humans and mice. Additionally, the CLOCK RevRE conferred REV-ERB responsiveness to a heterologous reporter gene. Our data suggests that REV-ERBα plays a dual role in regulation of the activity of the BMAL1/CLOCK heterodimer by regulation of expression of both the BMAL1 and CLOCK genes.
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Affiliation(s)
- Christine Crumbley
- The Scripps Research Institute, Jupiter, Florida, United States of America
| | - Thomas P. Burris
- The Scripps Research Institute, Jupiter, Florida, United States of America
- * E-mail:
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Crumbley C, Wang Y, Kojetin DJ, Burris TP. Characterization of the core mammalian clock component, NPAS2, as a REV-ERBalpha/RORalpha target gene. J Biol Chem 2010; 285:35386-92. [PMID: 20817722 DOI: 10.1074/jbc.m110.129288] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The mammalian clock is regulated at the cellular level by a transcriptional/translational feedback loop. BMAL1/clock (or NPAS2) heterodimers activate the expression of the period (PER) and cryptochrome (CRY) genes acting as transcription factors directed to the PER and CRY promoters via E-box elements. PER and CRY proteins form heterodimers and suppress the activity of the BMAL1/clock (or NPAS2) completing the feedback loop. The circadian expression of BMAL1 is influenced by retinoic acid receptor-related orphan receptor α (RORα) and REV-ERBα, two nuclear receptors that target a ROR-response element in the promoter of the BMAL1 gene. Given that BMAL1 functions as an obligate heterodimer with either clock or NPAS2, it is unclear how the expression of the partner is coordinated with BMAL1 expression. Here, we demonstrate that NPAS2 is also a RORα and REV-ERBα target gene. Using a ChIP/microarray screen, we identified both RORα and REV-ERBα occupancy of the NPAS2 promoter. We identified two functional ROREs within the NPAS2 promoter and also demonstrate that both RORα and REV-ERBα regulate the expression of NPAS2 mRNA. These data suggest a mechanism by which RORα and REV-ERBα coordinately regulate the expression of the positive arm of the circadian rhythm feedback loop.
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10
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Kumar N, Solt LA, Wang Y, Rogers PM, Bhattacharyya G, Kamenecka TM, Stayrook KR, Crumbley C, Floyd ZE, Gimble JM, Griffin PR, Burris TP. Regulation of adipogenesis by natural and synthetic REV-ERB ligands. Endocrinology 2010; 151:3015-25. [PMID: 20427485 PMCID: PMC2903944 DOI: 10.1210/en.2009-0800] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The nuclear hormone receptor, REV-ERB, plays an essential role in adipogenesis. Rev-erbalpha expression is induced in 3T3-L1 cells during adipogenesis, and overexpression of this receptor leads to expression of adipogenic genes. We recently demonstrated that the porphyrin heme functions as a ligand for REV-ERB, and binding of heme is required for the receptor's activity. We therefore hypothesized that REV-ERB ligands may play a role in regulation of adipogenesis. We detected an increase intracellular heme levels during 3T3-L1 adipogenesis that correlated with induction of aminolevulinic acid synthase 1 (Alas1) expression, the rate-limiting enzyme in heme biosynthesis. If the increase in Alas1 expression was blocked, adipogenesis was severely attenuated, indicating that induction of expression of Alas1 and the increase in heme synthesis is critical for differentiation. Inhibition of heme synthesis during adipogenesis leads to decreased recruitment of nuclear receptor corepressor to the promoter of a REV-ERB target gene, suggesting alteration of REV-ERB activity. Treatment of 3T3-L1 cells with a synthetic REV-ERB ligand, SR6452, resulted in induction of adipocyte differentiation to a similar extent as treatment with the peroxisomal proliferator-activated receptor-gamma agonist, rosiglitazone. Combination of SR6452 and rosiglitazone had an additive effect on stimulation of adipocyte differentiation. These results suggest that heme, functioning as a REV-ERB ligand, is an important signaling molecule for induction of adipogenesis. Moreover, synthetic small molecule ligands for REV-ERB are effective modulators of adipogenesis and may be useful for treatment of metabolic diseases.
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Affiliation(s)
- Naresh Kumar
- The Scripps Research Institute, 130 Scripps Way 2A1, Jupiter, FL 33458, USA
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Wang Y, Kumar N, Solt LA, Richardson TI, Helvering LM, Crumbley C, Garcia-Ordonez RD, Stayrook KR, Zhang X, Novick S, Chalmers MJ, Griffin PR, Burris TP. Modulation of retinoic acid receptor-related orphan receptor alpha and gamma activity by 7-oxygenated sterol ligands. J Biol Chem 2010; 285:5013-25. [PMID: 19965867 PMCID: PMC2836105 DOI: 10.1074/jbc.m109.080614] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 12/04/2009] [Indexed: 01/07/2023] Open
Abstract
The retinoic acid receptor-related orphan receptors alpha and gamma (RORalpha (NR1F1) and RORgamma (NR1F3)) are orphan nuclear receptors and perform critical roles in regulation of development, metabolism, and immune function. Cholesterol and cholesterol sulfate have been suggested to be RORalpha ligands, but the physiological significance is unclear. To date, no endogenous RORgamma ligands have been described. Here, we demonstrate that 7-oxygenated sterols function as high affinity ligands for both RORalpha and RORgamma by directly binding to their ligand-binding domains (K(i) approximately 20 nM), modulating coactivator binding, and suppressing the transcriptional activity of the receptors. One of the 7-oxygenated sterols, 7alpha-hydroxycholesterol (7alpha-OHC), serves as a key intermediate in bile acid metabolism, and we show that 7alpha-OHC modulates the expression of ROR target genes, including Glc-6-Pase and phosphoenolpyruvate carboxykinase, in an ROR-dependent manner. Furthermore, glucose output from hepatocytes is suppressed by 7alpha-OHC functioning as an RORalpha/gamma ligand. Thus, RORalpha and RORgamma are ligand-regulated members of the NR superfamily and may serve as sensors for 7-oxygenated sterols.
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Affiliation(s)
- Yongjun Wang
- From the Scripps Research Institute, Jupiter, Florida 33458 and
| | - Naresh Kumar
- From the Scripps Research Institute, Jupiter, Florida 33458 and
| | - Laura A. Solt
- From the Scripps Research Institute, Jupiter, Florida 33458 and
| | | | | | | | | | | | - Xi Zhang
- From the Scripps Research Institute, Jupiter, Florida 33458 and
| | - Scott Novick
- From the Scripps Research Institute, Jupiter, Florida 33458 and
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Miller A, Crumbley C, Prüfer K. The N-terminal nuclear localization sequences of liver X receptors alpha and beta bind to importin alpha and are essential for both nuclear import and transactivating functions. Int J Biochem Cell Biol 2008; 41:834-43. [PMID: 18773967 DOI: 10.1016/j.biocel.2008.08.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 08/05/2008] [Accepted: 08/12/2008] [Indexed: 01/27/2023]
Abstract
Liver X receptors (LXRs) alpha and beta are nuclear receptors, which form obligate heterodimers with the retinoid X receptor (RXR). The LXRs regulate both redundantly and non-redundantly the transcription of genes controlling cholesterol metabolism and transport as well as lipogenesis. Previously, we showed that mutations in putative N-terminal nuclear localization sequences (NLSs) within both LXRs inhibit nuclear import. Through in vitro studies, we show here that these NLSs bind importin alpha and are both necessary and sufficient for the nuclear import of LXRs. Imaging, transactivation, and electro-mobility shift experiments show that RXR rescues the nuclear import of the LXRalpha NLS mutant yet does not restore its transcriptional activity despite intact DNA binding. In contrast, RXR partially rescues the import of the LXRbeta NLS mutant, but has no effect on its transcriptional activity due to the loss of DNA binding. Experiments with NLS mutant RXR confirmed that RXR may dominate the nuclear import of the RXR/LXRalpha heterodimer, whereas LXRbeta dominates the nuclear import of the RXR/LXRbeta heterodimer. Intriguingly, our data indicate differences between LXRalpha and LXRbeta in their interaction with RXR and in the role their NLSs play in transactivating functions independent of nuclear import.
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Affiliation(s)
- Anna Miller
- Department of Biological Sciences, A243 Life Science Building, Louisiana State University, Baton Rouge, LA 70803, USA
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