Loss of TR4 Orphan Nuclear Receptor Reduces Phosphoenolpyruvate Carboxykinase–Mediated Gluconeogenesis

• Published in: Diabetes (New York, N.Y.) Vol. 56; no. 12; pp. 2901 - 2909
• Main Authors: LIU, Ning-Chun, LIN, Wen-Jye, KIM, Eungseok, COLLINS, Loretta L, LIN, Hung-Yun, YU, I-Chen, SPARKS, Janet D, CHEN, Lu-Min, LEE, Yi-Fen, CHANG, Chawnshang
• Format: Journal Article
• Language: English
• Published: Alexandria, VA American Diabetes Association 01.12.2007
• Subjects: Animals; Biological and medical sciences; Cells, Cultured; Diabetes; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Enzymes; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Gene expression; Gene Expression Regulation; Gluconeogenesis; Gluconeogenesis - physiology; Glucose; Health aspects; Hepatocytes - physiology; Homeostasis; Hyperglycemia; Hypoglycemia; Insulin; Kinases; Liver; Male; Medical sciences; Metabolism; Phosphoenolpyruvate carboxykinase; Phosphoenolpyruvate Carboxykinase (ATP) - metabolism; Plasmids; Polymerase Chain Reaction; Promoter Regions, Genetic; Proteins; Rats; Receptors, Steroid - deficiency; Receptors, Steroid - genetics; Receptors, Steroid - physiology; Receptors, Thyroid Hormone - deficiency; Receptors, Thyroid Hormone - genetics; Receptors, Thyroid Hormone - physiology; Research design; Risk factors; RNA Interference; Transcription, Genetic; Transfection; New York; Endocrinopathy; Carbon-carbon lyases; Nuclear receptor; Enzyme; Carboxy-lyases; Diabetes mellitus; Lyases; Phosphoenolpyruvate carboxykinase (ATP); Orphan receptor; Gluconeogenesis
• ISSN: 0012-1797; 1939-327X
• DOI: 10.2337/db07-0359

Loss of TR4 Orphan Nuclear Receptor Reduces Phosphoenolpyruvate Carboxykinase–Mediated Gluconeogenesis Ning-Chun Liu 1 , Wen-Jye Lin 1 , Eungseok Kim 1 2 , Loretta L. Collins 1 , Hung-Yun Lin 1 , I-Chen Yu 1 , Janet D. Sparks 1 , Lu-Min Chen 1 3 , Yi-Fen Lee 1 and Chawnshang Chang 1 1 George Whipple Laboratory for Cancer Research, Department of Pathology, Urology, and Radiation Oncology and the Cancer Center, University of Rochester, Rochester, New York 2 Department of Biological Sciences, Chonnam National University, Gwangju, Korea 3 Department of Obstetrics and Gynecology, China Medical University/Hospital, Taichung, Taiwan, Republic of China Address correspondence and reprint requests to Chawnshang Chang, PhD, Department of Pathology, University of Rochester, Rochester, NY 14642. E-mail: chang{at}urmc.rochester.edu ; and Yi-Fen Lee, PhD, Department of Urology, University of Rochester, Rochester, NY 14642. E-mail: yifen_lee{at}urmc.rochester.edu Abstract OBJECTIVE— Regulation of phosphoenolpyruvate carboxykinase (PEPCK), the key gene in gluconeogenesis, is critical for glucose homeostasis in response to quick nutritional depletion and/or hormonal alteration. RESEARCH DESIGN/METHODS AND RESULTS— Here, we identified the testicular orphan nuclear receptor 4 (TR4) as a key PEPCK regulator modulating PEPCK gene via a transcriptional mechanism. TR4 transactivates the 490-bp PEPCK promoter-containing luciferase reporter gene activity by direct binding to the TR4 responsive element (TR4RE) located at −451 to −439 in the promoter region. Binding to TR4RE was confirmed by electrophoretic mobility shift and chromatin immunoprecipitation assays. Eliminating TR4 via knockout and RNA interference (RNAi) in hepatocytes significantly reduced the PEPCK gene expression and glucose production in response to glucose depletion. In contrast, ectopic expression of TR4 increased PEPCK gene expression and hepatic glucose production in human and mouse hepatoma cells. Mice lacking TR4 also display reduction of PEPCK expression with impaired gluconeogenesis. CONCLUSIONS— Together, both in vitro and in vivo data demonstrate the identification of a new pathway, TR4 → PEPCK → gluconeogenesis → blood glucose, which may allow us to modulate metabolic programs via the control of a new key player, TR4, a member of the nuclear receptor superfamily. AUC, area under the curve ChIP, chromatin immunoprecipitation DMEM, Dulbecco’s modified Eagle’s medium DR, direct repeat EMSA, electrophoretic mobility shift assay HGP, hepatic glucose production HOMA, homeostasis model assessment HRE, hormone response element PEPCK, phosphoenolpyruvate carboxykinase PKA, cAMP-dependent protein kinase QUICKI, quantitative insulin-sensitivity check index TR4, testicular orphan nuclear receptor 4 TR4RE, TR4 responsive element Footnotes Published ahead of print at http://diabetes.diabetesjournals.org on 7 September 2007. DOI: 10.2337/db07-0359. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Accepted August 31, 2007. Received March 19, 2007. DIABETES