title: Renal medullary microRNAs in Dahl salt-sensitive rats: miR-29b regulates several collagens and related genes.
abstract: MicroRNAs are endogenous repressors of gene expression. We examined microRNAs in the renal medulla of Dahl salt-sensitive rats and consomic SS-13(BN) rats. Salt-induced hypertension and renal injury in Dahl salt-sensitive rats, particularly medullary interstitial fibrosis, have been shown previously to be substantially attenuated in SS-13(BN) rats. Of 377 microRNAs examined, 5 were found to be differentially expressed between Dahl salt-sensitive rats and consomic SS-13(BN) rats receiving a high-salt diet. Real-time PCR analysis demonstrated that high-salt diets induced substantial upregulation of miR-29b in the renal medulla of SS-13(BN) rats but not in SS rats. miR-29b was predicted to regulate 20 collagen genes, matrix metalloproteinase 2 (Mmp2), integrin beta1 (Itgb1), and other genes related to the extracellular matrix. Expression of 9 collagen genes and Mmp2 was upregulated by a high-salt diet in the renal medulla of SS rats, but not in SS-13(BN) rats, an expression pattern opposite to miR-29b. Knockdown of miR-29b in the kidneys of SS-13(BN) rats resulted in upregulation of several collagen genes. miR-29b reduced expression levels of several collagen genes and Itgb1 in cultured rat renal medullary epithelial cells. Moreover, miR-29b suppressed the activity of luciferase when the reporter gene was linked to a 3'-untranslated segment of collagen genes Col1a1, Col3a1, Col4a1, Col5a1, Col5a2, Col5a3, Col7a1, Col8a1, Mmp2, or Itgb1 but not Col12a1. The result demonstrated broad effects of miR-29b on a large number of collagens and genes related to the extracellular matrix and suggested involvement of miR-29b in the protection from renal medullary injury in SS-13(BN) rats.
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee, Wis, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.forename: Norman E
authors.initials: NE
authors.lastname: Taylor
authors.forename: Limin
authors.initials: L
authors.lastname: Lu
authors.forename: Kristie
authors.initials: K
authors.lastname: Usa
authors.forename: Allen W
authors.initials: AW
authors.lastname: Cowley
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Ferreri
authors.forename: Nan Cher
authors.initials: NC
authors.lastname: Yeo
authors.forename: Mingyu
authors.initials: M
authors.lastname: Liang
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000235:genetics; D015153:Blotting, Western; D003094:Collagen / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism; D007679:Kidney Medulla / Q000502:physiology*; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020303:Rats, Inbred Dahl; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage
chemical_list: D019012:Integrin beta1; D035683:MicroRNAs; D012333:RNA, Messenger; D017673:Sodium Chloride, Dietary; D003094:Collagen; D020778:Matrix Metalloproteinase 2