miR-200a Prevents renal fibrogenesis through repression of TGF-β2 expression.
OBJECTIVE
Progressive fibrosis in the diabetic kidney is driven and sustained by a diverse range of profibrotic factors. This study examines the critical role of microRNAs (miRNAs) in the regulation of the key fibrotic mediators, TGF-β1 and TGF-β2.


METHODS
Rat proximal-tubular epithelial cells (NRK52E) were treated with TGF-β1 and TGF-β2 for 3 days, and expression of markers of epithelial-to-mesenchymal transition (EMT) and fibrogenesis were assessed by RT-PCR and Western blotting. The expression of miR-141 and miR-200a was also assessed, as was their role as translational repressors of TGF-β signaling. Finally, these pathways were explored in two different mouse models, representing early and advanced diabetic nephropathy.


RESULTS
Both TGF-β1 and TGF-β2 induced EMT and fibrogenesis in NRK52E cells. TGF-β1 and TGF-β2 also downregulated expression of miR-200a. The importance of these changes was demonstrated by the finding that ectopic expression miR-200a downregulated smad-3 activity and the expression of matrix proteins and prevented TGF-β-dependent EMT. miR-200a also downregulated the expression of TGF-β2, via direct interaction with the 3' untranslated region of TGF-β2. The renal expression of miR-141 and miR-200a was also reduced in mouse models representing early and advanced kidney disease.


CONCLUSIONS
miR-200a and miR-141 significantly impact on the development and progression of TGF-β-dependent EMT and fibrosis in vitro and in vivo. These miRNAs appear to be intricately involved in fibrogenesis, both as downstream mediators of TGF-β signaling and as components of feedback regulation, and as such represent important new targets for the prevention of progressive kidney disease in the context of diabetes.
Wang
Bo
B
JDRF Danielle Alberti Memorial Centre for Diabetes Complications, Melbourne, Australia.
Koh
Philip
P
Winbanks
Catherine
C
Coughlan
Melinda T
MT
McClelland
Aaron
A
Watson
Anna
A
Jandeleit-Dahm
Karin
K
Burns
Wendy C
WC
Thomas
Merlin C
MC
Cooper
Mark E
ME
Kantharidis
Phillip
P
D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D002460:Cell Line; D003928:Diabetic Nephropathies / Q000473:pathology / Q000503:physiopathology; D015536:Down-Regulation; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000235:genetics; D005786:Gene Expression Regulation; D020868:Gene Silencing; D017930:Genes, Reporter; D006801:Humans; D007684:Kidney Tubules / Q000502:physiology; D008156:Luciferases / Q000235:genetics; D008648:Mesoderm / Q000166:cytology / Q000502:physiology; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology; D053781:Transforming Growth Factor beta2 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000276:immunology
D020413:3' Untranslated Regions; D016326:Extracellular Matrix Proteins; D035683:MicroRNAs; C543719:Mirn200 microRNA, mouse; D051900:Smad3 Protein; D053773:Transforming Growth Factor beta1; D053781:Transforming Growth Factor beta2; D012313:RNA; D008156:Luciferases