title: miR-33 links SREBP-2 induction to repression of sterol transporters.
abstract: The sterol regulatory element binding protein 2 (SREBP-2) and the liver X receptor (LXR) control antagonistic transcriptional programs that stimulate cellular cholesterol uptake and synthesis, and cholesterol efflux, respectively. The clinical importance of SREBP-2 is revealed in patients with hypercholesterolemia treated with statins, which reduce low-density lipoprotein (LDL) cholesterol levels by increasing hepatic expression of SREBP-2 and its target, the LDL receptor. Here we show that miR-33 is encoded within SREBP-2 and that both mRNAs are coexpressed. We also identify sequences in the 3' UTR of ABCA1 and ABCG1, sterol transporter genes both previously shown to be regulated by LXR, as targets for miR-33-mediated silencing. Our data show that LXR-dependent cholesterol efflux to both ApoAI and serum is ameliorated by miR-33 overexpression and, conversely, stimulated by miR-33 silencing. Finally, we show that ABCA1 mRNA and protein and plasma HDL levels decline after hepatic overexpression of miR-33, whereas they increase after hepatic miR-33 silencing. These results suggest novel ways to manage hypercholesterolemic patients.
authors.affiliation: Edward A Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, St Louis, MO 63104, USA.
authors.forename: Tyler J
authors.initials: TJ
authors.lastname: Marquart
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Allen
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Ory
authors.forename: Angel
authors.initials: A
authors.lastname: Baldán
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D064286:ATP Binding Cassette Transporter 1; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002784:Cholesterol / Q000097:blood / Q000378:metabolism; D008076:Cholesterol, HDL / Q000097:blood; D005786:Gene Expression Regulation; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011973:Receptors, LDL / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051782:Sterol Regulatory Element Binding Protein 2 / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D020121:5' Untranslated Regions; C577836:ABCA1 protein, human; C419353:ABCG1 protein, human; D064286:ATP Binding Cassette Transporter 1; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters; D008076:Cholesterol, HDL; D008077:Lipoproteins, LDL; C550416:MIRN33a microRNA, human; D035683:MicroRNAs; C550417:Mirn33 microRNA, mouse; D012333:RNA, Messenger; D011973:Receptors, LDL; D051782:Sterol Regulatory Element Binding Protein 2; D002784:Cholesterol