title: Thioredoxin-interacting protein mediates high glucose-induced reactive oxygen species generation by mitochondria and the NADPH oxidase, Nox4, in mesangial cells.
abstract: Thioredoxin-interacting protein (TxNIP) is up-regulated by high glucose and is associated with oxidative stress. It has been implicated in hyperglycemia-induced β-cell dysfunction and apoptosis. As high glucose and oxidative stress mediate diabetic nephropathy (DN), the contribution of TxNIP was investigated in renal mesangial cell reactive oxygen species (ROS) generation and collagen synthesis. To determine the role of TxNIP, mouse mesangial cells (MC) cultured from wild-type C3H and TxNIP-deficient Hcb-19 mice were incubated in HG. Confocal microscopy was used to measure total and mitochondrial ROS production (DCF and MitoSOX) and collagen IV. Trx and NADPH oxidase activities were assayed and NADPH oxidase isoforms, Nox2 and Nox4, and antioxidant enzymes were determined by immunoblotting. C3H MC exposed to HG elicited a significant increase in cellular and mitochondrial ROS as well as Nox4 protein expression and NADPH oxidase activation, whereas Hcb-19 MC showed no response. Trx activity was attenuated by HG only in C3H MC. These defects in Hcb-19 MC were not due to increased antioxidant enzymes or scavenging of ROS, but associated with decreased ROS generation. Adenovirus-mediated overexpression of TxNIP in Hcb-19 MC and TxNIP knockdown with siRNA in C3H confirmed the specific role of TxNIP. Collagen IV accumulation in HG was markedly reduced in Hcb-19 cells. TxNIP is a critical component of the HG-ROS signaling pathway, required for the induction of mitochondrial and total cell ROS and the NADPH oxidase isoform, Nox4. TxNIP is a potential target to prevent DN.
authors: Department of Medicine and Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario M5T 3L9, Canada.
authors: Anu
authors: A
authors: Shah
authors: Ling
authors: L
authors: Xia
authors: Howard
authors: H
authors: Goldberg
authors: Ken W
authors: KW
authors: Lee
authors: Susan E
authors: SE
authors: Quaggin
authors: I George
authors: IG
authors: Fantus
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D024141:Collagen Type IV / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D050527:Mesangial Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013879:Thioredoxins / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D024141:Collagen Type IV; D017382:Reactive Oxygen Species; C486715:TXNIP protein, human; C515559:Txn1 protein, mouse; D013879:Thioredoxins; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C422943:Nox4 protein, mouse; D005947:Glucose