MicroRNA-192 in diabetic kidney glomeruli and its function in TGF-beta-induced collagen expression via inhibition of E-box repressors.
Key features of diabetic nephropathy (DN) include the accumulation of extracellular matrix proteins such as collagen 1-alpha 1 and -2 (Col1a1 and -2). Transforming growth factor beta1 (TGF-beta), a key regulator of these extracellular matrix genes, is increased in mesangial cells (MC) in DN. By microarray profiling, we noted that TGF-beta increased Col1a2 mRNA in mouse MC (MMC) but also decreased mRNA levels of an E-box repressor, deltaEF1. TGF-beta treatment or short hairpin RNAs targeting deltaEF1 increased enhancer activity of upstream E-box elements in the Col1a2 gene. TGF-beta also decreased the expression of Smad-interacting protein 1 (SIP1), another E-box repressor similar to deltaEF1. Interestingly, we noted that SIP1 is a target of microRNA-192 (miR-192), a key miR highly expressed in the kidney. miR-192 levels also were increased by TGF-beta in MMC. TGF-beta treatment or transfection with miR-192 decreased endogenous SIP1 expression as well as reporter activity of a SIP1 3' UTR-containing luciferase construct in MMC. Conversely, a miR-192 inhibitor enhanced the luciferase activity, confirming SIP1 to be a miR-192 target. Furthermore, miR-192 synergized with deltaEF1 short hairpin RNAs to increase Col1a2 E-box-luc activity. Importantly, the in vivo relevance was noted by the observation that miR-192 levels were enhanced significantly in glomeruli isolated from streptozotocin-injected diabetic mice as well as diabetic db/db mice relative to corresponding nondiabetic controls, in parallel with increased TGF-beta and Col1a2 levels. These results uncover a role for miRs in the kidney and DN in controlling TGF-beta-induced Col1a2 expression by down-regulating E-box repressors.
Kato
Mitsuo
M
Gonda Diabetes Center, Division of Molecular Biology, Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA.
Zhang
Jane
J
Wang
Mei
M
Lanting
Linda
L
Yuan
Hang
H
Rossi
John J
JJ
Natarajan
Rama
R
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D003094:Collagen / Q000378:metabolism*; D024042:Collagen Type I; D017931:DNA Primers; D003928:Diabetic Nephropathies / Q000235:genetics* / Q000378:metabolism; D024721:E-Box Elements / Q000235:genetics; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000378:metabolism; D050527:Mesangial Cells / Q000378:metabolism*; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D012097:Repressor Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D000071799:Zinc Finger E-box-Binding Homeobox 1
D003094:Collagen; D024042:Collagen Type I; D017931:DNA Primers; D018398:Homeodomain Proteins; D035683:MicroRNAs; D009419:Nerve Tissue Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; C491561:Sip1 protein, mouse; C519422:ZEB1 protein, mouse; D000071799:Zinc Finger E-box-Binding Homeobox 1