title: microRNA-185 modulates low density lipoprotein receptor expression as a key posttranscriptional regulator.
abstract: OBJECTIVE
  Low-density lipoprotein receptor (LDLR) mediates endocytosis of LDL particles and is important in maintaining plasma cholesterol levels, thus its expression is under extensive regulation at multiple levels, including transcriptional and posttranscriptional regulation by transcription factors (TFs) and RNA-binding proteins (RBPs). Here, we identified microRNA-185 (miR-185) as a novel direct posttranscriptional regulator of LDLR and an indirect LDLR modulator through KSRP in hepatic cells.
  
  
  RESULTS
  Using quantitative real-time PCR (qPCR), we detected the effect of predicted LDLR-targeting miRNAs and found that overexpression of miR-185 repressed LDLR expression and LDL uptake in HepG2 cells by 62.4 ± 6.0% (p = 7.0 × 10(-5)) and 32.5 ± 6.0% (p = 7.7 × 10(-4)) respectively, through directly targeting LDLR 3'UTR. Unexpectedly, the antisense inhibitor of miR-185 had similar repression effect on LDLR although it reduced the association of endogenous miR-185 with LDLR mRNA. Further experiments revealed that KH-type splicing regulatory protein (KSRP), one of the LDLR-destabilizing RBPs, is also a target of miR-185. KSRP silencing reversed the repression effects of miR-185-inhibitor on LDLR. Thus miR-185 regulates LDLR expression not only through directly targeting but also by a RBP-involved indirect pathway. Finally, the in vivo results showed that miR-185-inhibitor upregulated hepatic LDLR expression and correlated with a decrease in plasma cholesterol level and arterial plaque area in ApoE KO mice.
  
  
  CONCLUSIONS
  These findings reveal that miR-185 controls cholesterol homeostasis as a key posttranscriptional LDLR modulator in hepatic cells, providing novel insight into the regulatory mechanism for LDLR expression and the anti-atherosclerosis effect of miR-185-inhibitor.
authors.affiliation: Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China.
authors.forename: Huajun
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Du
authors.affiliation: Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China.
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Jia
authors.affiliation: Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.affiliation: Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China.
authors.forename: Shuyi
authors.initials: S
authors.lastname: Si
authors.affiliation: Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China. Electronic address: capricornkey@163.com.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: Key Laboratory of Biotechnology of Antibiotics of Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Tiantan Xili, Beijing 100050, China. Electronic address: binhong69@hotmail.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Hong
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000473:pathology; D001018:Aortic Diseases / Q000097:blood / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D001057:Apolipoproteins E / Q000172:deficiency / Q000235:genetics; D050197:Atherosclerosis / Q000097:blood / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D001483:Base Sequence; D015415:Biomarkers / Q000097:blood; D002784:Cholesterol / Q000097:blood; D004195:Disease Models, Animal; D004705:Endocytosis; D005786:Gene Expression Regulation; D056945:Hep G2 Cells; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D058226:Plaque, Atherosclerotic; D034622:RNA Interference; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D011973:Receptors, LDL / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D020413:3' Untranslated Regions; D001057:Apolipoproteins E; D015415:Biomarkers; C105789:KHSRP protein, human; C573412:LDLR protein, human; D008077:Lipoproteins, LDL; C552431:MIRN185 microRNA, human; D035683:MicroRNAs; C578934:Mirn185 microRNA, mouse; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011973:Receptors, LDL; D015534:Trans-Activators; D002784:Cholesterol
keywords: Cholesterol metabolism; Low density lipoprotein receptor (LDLR); Posttranscriptional regulation; RNA-binding proteins (RBPs); microRNA