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.
JDRF Danielle Alberti Memorial Centre for Diabetes Complications, Melbourne, Australia.
Bo
B
Wang
Philip
P
Koh
Catherine
C
Winbanks
Melinda T
MT
Coughlan
Aaron
A
McClelland
Anna
A
Watson
Karin
K
Jandeleit-Dahm
Wendy C
WC
Burns
Merlin C
MC
Thomas
Mark E
ME
Cooper
Phillip
P
Kantharidis
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