title: Type 1 Deiodinase Regulates ApoA-I Gene Expression and ApoA-I Synthesis Independent of Thyroid Hormone Signaling.
abstract: Plasma levels of high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (ApoA-I) are reduced in individuals with defective insulin signaling. Initial studies using liver-specific insulin receptor (InsR) knockout mice identified reduced expression of type 1 deiodinase (Dio1) as a potentially novel link between defective hepatic insulin signaling and reduced expression of the ApoA-I gene. Our objective was to examine the regulation of ApoA-I expression by Dio1.
  
  
  
  Acute inactivation of InsR by adenoviral delivery of Cre recombinase to InsR floxed mice reduced HDL-C and expression of both ApoA-I and Dio1. Overexpression of Dio1 in InsR knockout mice restored HDL-C and ApoA-I levels and increased the expression of ApoA-I. Dio1 knockout mice had low expression of ApoA-I and reduced serum levels of HDL-C and ApoA-I. Treatment of C57BL/6J mice with antisense to Dio1 reduced ApoA-I mRNA, HDL-C, and serum ApoA-I. Hepatic 3,5,3'-triiodothyronine content was normal or elevated in InsR knockout mice or Dio1 knockout mice. Knockdown of either InsR or Dio1 by siRNA in HepG2 cells decreased the expression of ApoA-I and ApoA-I synthesis and secretion. siRNA knockdown of InsR or Dio1 decreased activity of a region of the ApoA-I promoter lacking thyroid hormone response elements (region B). Electrophoretic mobility shift assay demonstrated that reduced Dio1 expression decreased the binding of nuclear proteins to region B.
  
  
  
  Reductions in Dio1 expression reduce the expression of ApoA-I in a 3,5,3'-triiodothyronine-/thyroid hormone response element-independent manner.
authors.affiliation: From the Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY (J.L., A.H.-O., H.N.G.); Ionis Pharmaceuticals, Inc, Carlsbad, CA (M.J.G.); and Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, NH (V.A.G.). jl3518@cumc.columbia.edu hng1@cumc.columbia.edu.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: From the Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY (J.L., A.H.-O., H.N.G.); Ionis Pharmaceuticals, Inc, Carlsbad, CA (M.J.G.); and Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, NH (V.A.G.).
authors.forename: Antonio
authors.initials: A
authors.lastname: Hernandez-Ono
authors.affiliation: From the Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY (J.L., A.H.-O., H.N.G.); Ionis Pharmaceuticals, Inc, Carlsbad, CA (M.J.G.); and Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, NH (V.A.G.).
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Graham
authors.affiliation: From the Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY (J.L., A.H.-O., H.N.G.); Ionis Pharmaceuticals, Inc, Carlsbad, CA (M.J.G.); and Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, NH (V.A.G.).
authors.forename: Valerie Anne
authors.initials: VA
authors.lastname: Galton
authors.affiliation: From the Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY (J.L., A.H.-O., H.N.G.); Ionis Pharmaceuticals, Inc, Carlsbad, CA (M.J.G.); and Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, NH (V.A.G.). jl3518@cumc.columbia.edu hng1@cumc.columbia.edu.
authors.forename: Henry N
authors.initials: HN
authors.lastname: Ginsberg
mesh_terms: D000818:Animals; D016632:Apolipoprotein A-I / Q000097:blood / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008076:Cholesterol, HDL / Q000097:blood; D005786:Gene Expression Regulation; D005838:Genotype; D056945:Hep G2 Cells; D006801:Humans; D007453:Iodide Peroxidase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011972:Receptor, Insulin / Q000172:deficiency / Q000235:genetics; D020218:Response Elements; D015398:Signal Transduction; D014162:Transfection; D014284:Triiodothyronine / Q000378:metabolism*
chemical_list: C505693:APOA1 protein, human; D016632:Apolipoprotein A-I; D008076:Cholesterol, HDL; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D014284:Triiodothyronine; D007453:Iodide Peroxidase; C507436:selenodeiodinase type 1, mouse; D011972:Receptor, Insulin
keywords: apolipoprotein A-I; cholesterol, HDL; electrophoretic mobility shift assay; mice, knockout; response element; type 1 deiodinase