title: MicroRNA-200b downregulates oxidation resistance 1 (Oxr1) expression in the retina of type 1 diabetes model.
abstract: OBJECTIVE
  MicroRNAs (miRNAs) are known to participate in post-transcriptional regulation of gene expression and are involved in multiple pathogenic processes. Here, we identified miRNA expression changes in the retinas of Akita mice, a genetic model of type 1 diabetes, and investigated the potential role of miRNA in diabetic retinopathy.
  
  
  METHODS
  Visual function of Akita and control mice was evaluated by electroretinography. MiRNA expression changes in the retinas of Akita mice were identified by miRNA-specific microarray and confirmed by quantitative RT-PCR (qRT-PCR). The potential downstream targets of identified miRNAs were predicted by bioinformatic analysis using web-based applications and confirmed by dual luciferase assay. The mRNA and protein changes of identified downstream targets were examined by qRT-PCR and Western blot analysis.
  
  
  RESULTS
  MiRNA-specific microarray and qRT-PCR showed that miR-200b was upregulated significantly in the Akita mouse retina. Sequence analysis and luciferase assay identified oxidation resistance 1 (Oxr1) as a downstream target gene regulated by miR-200b. In a human Müller cell line, MIO-M1, transfection of a miR-200b mimic downregulated Oxr1 expression. Conversely, transfection of MIO-M1 with a miR-200b inhibitor resulted in upregulated Oxr1. Furthermore, overexpression of recombinant Oxr1 attenuated oxidative stress marker, nitration of cellular proteins, and ameliorated apoptosis induced by 4-hydroxynonenal (4-HNE), an oxidative stressor. Similarly, transfection of a miR-200b inhibitor decreased, whereas transfection of miR-200b mimic increased the number of apoptotic cells following 4-HNE treatment.
  
  
  CONCLUSIONS
  These results suggested that miR-200b-regulated Oxr1 potentially has a protective role in diabetic retinopathy.
authors: Department of Physiology, University of Oklahoma Health Sciences Center, 941 Stanton L. Young Boulevard, Oklahoma City, OK 73104, USA.
authors: Anne R
authors: AR
authors: Murray
authors: Qian
authors: Q
authors: Chen
authors: Yusuke
authors: Y
authors: Takahashi
authors: Kevin K
authors: KK
authors: Zhou
authors: Kyoungmin
authors: K
authors: Park
authors: Jian-xing
authors: JX
authors: Ma
mesh_terms: D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D003922:Diabetes Mellitus, Type 1; D003930:Diabetic Retinopathy / Q000235:genetics*; D004195:Disease Models, Animal; D015536:Down-Regulation; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D064446:Orexin Receptors; D018384:Oxidative Stress / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000502:physiology; D060888:Real-Time Polymerase Chain Reaction; D018013:Receptors, Neuropeptide / Q000235:genetics* / Q000378:metabolism; D012160:Retina / Q000378:metabolism*; D014162:Transfection; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: C497459:Hcrtr1 protein, mouse; C555600:MIRN200 microRNA, rat; D035683:MicroRNAs; D064446:Orexin Receptors; D012333:RNA, Messenger; D018013:Receptors, Neuropeptide; C002744:3-nitrotyrosine; D014443:Tyrosine
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