title: Transcriptional and Translational Modulation of myo-Inositol Oxygenase (Miox) by Fatty Acids: IMPLICATIONS IN RENAL TUBULAR INJURY INDUCED IN OBESITY AND DIABETES.
abstract: The kidney is one of the target organs for various metabolic diseases, including diabetes, metabolic syndrome, and obesity. Most of the metabolic studies underscore glomerular pathobiology, although the tubulo-interstitial compartment has been underemphasized. This study highlights mechanisms concerning the pathobiology of tubular injury in the context of myo-inositol oxygenase (Miox), a tubular enzyme. The kidneys of mice fed a high fat diet (HFD) had increased Miox expression and activity, and the latter was related to phosphorylation of serine/threonine residues. Also, expression of sterol regulatory element-binding protein1 (Srebp1) and markers of cellular/nuclear damage was increased along with accentuated apoptosis and loss of tubular brush border. Similar results were observed in cells treated with palmitate/BSA. Multiple sterol-response elements and E-box motifs were found in the miox promoter, and its activity was modulated by palmitate/BSA. Electrophoretic mobility and ChIP assays confirmed binding of Srebp to consensus sequences of the miox promoter. Exposure of palmitate/BSA-treated cells to rapamycin normalized Miox expression and prevented Srebp1 nuclear translocation. In addition, rapamycin treatment reduced p53 expression and apoptosis. Like rapamycin, srebp siRNA reduced Miox expression. Increased expression of Miox was associated with the generation of reactive oxygen species (ROS) in kidney tubules of mice fed an HFD and cell exposed to palmitate/BSA. Both miox and srebp1 siRNAs reduced generation of ROS. Collectively, these findings suggest that HFD or fatty acids modulate transcriptional, translational, and post-translational regulation of Miox expression/activity and underscore Miox being a novel target of the transcription factor Srebp1. Conceivably, activation of the mTORC1/Srebp1/Miox pathway leads to the generation of ROS culminating into tubulo-interstitial injury in states of obesity.
authors.affiliation: From the Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611 and.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Tominaga
authors.affiliation: From the Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611 and.
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Dutta
authors.affiliation: From the Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611 and.
authors.forename: Darukeshwara
authors.initials: D
authors.lastname: Joladarashi
authors.affiliation: the Department of Nephrology, University of Tokushima, Tokushima, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Doi
authors.affiliation: From the Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611 and.
authors.forename: Janardan K
authors.initials: JK
authors.lastname: Reddy
authors.affiliation: From the Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611 and y-kanwar@northwestern.edu.
authors.forename: Yashpal S
authors.initials: YS
authors.lastname: Kanwar
mesh_terms: D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D003928:Diabetic Nephropathies / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D059305:Diet, High-Fat / Q000009:adverse effects; D006801:Humans; D050562:Inositol Oxygenase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007684:Kidney Tubules / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D009765:Obesity / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress; D010105:Oxygenases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D051381:Rats; D051780:Sterol Regulatory Element Binding Protein 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034421:Sus scrofa; D015854:Up-Regulation
chemical_list: D011506:Proteins; D051780:Sterol Regulatory Element Binding Protein 1; D010105:Oxygenases; D050562:Inositol Oxygenase; C485890:MIOX protein, human; C414007:Miox protein, rat
keywords: diabetic nephropathy; fatty acid; kidney; kidney metabolism; myo-inositol oxygenase; obesity; renal tubular injury