Sitagliptin ameliorates oxidative stress in experimental diabetic nephropathy by diminishing the miR-200a/Keap-1/Nrf2 antioxidant pathway

Esther Civantos,1,2 Enrique Bosch,1 Elisa Ramirez,1 Olha Zhenyukh,1 Jesús Egido,1,2 Oscar Lorenzo,1,2 Sebastián Mas1,2 1Renal, Vascular and Diabetes Research Laboratory, IIS-Fundación Jiménez Díaz, Autonoma University, 2CIBERDEM (Biomedical Research Centre in Diabetes and Associated Metabolic Disorders), Madrid, Spain Background: Sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor used in type 2 diabetes therapy, has demonstrated protective effects in diabetic chronic kidney disease, in part due to its pleiotropic actions. However, its potential direct effects on the kidney are still not completely defined. Here, by means of proteomics and miRNA profiling, we have further unveiled the role of sitagliptin in oxidative stress, as well as the underlying mechanisms.Methods: Renal cortex samples from 9-month-old wild-type (Wistar), type II diabetic Goto-Kakizaki (GK) and sitagliptin-treated GK rats (GK+Sita) (10 mg kg−1 per day) were subjected to quantitative miRNA transcriptomic array, immunohistochemistry and Western blot studies. Renal GK and GK+Sita samples were also analyzed by differential in-gel electrophoresis. Bioinformatic tools were used to find out the relationships between altered proteins and related miRNA expression. Studies were also carried out in cultured tubular cells to confirm in vivo data.Results: Diabetic GK rats exhibited proteinuria, renal interstitial inflammatory infiltrates and fibrosis, which improved by 20 weeks of sitagliptin treatment. Proteomic analysis of diabetic GK and Wistar rats showed a differential expression of 39 proteins mostly related to oxidative stress and catabolism. In addition, 15 miRNAs were also significantly altered in GK rats.Conclusion: Treatment with sitagliptin was associated with modulation of antioxidant response in the diabetic kidney, involving a downregulation of miR-200a, a novel Keap-1 inhibitor and miR-21, coincidentally with the clinical and the morphological improvement. These data further support the concept that DPP-4 inhibitors could exert a direct reno-protective effect in patients with diabetic nephropathy. Keywords: diabetes, sitagliptin, Nrf2, Keap-1, miRNAs, GK rat

HuR mediates the synergistic effects of angiotensin II and IL-1β on vascular COX-2 expression and cell migration

This is the peer-reviewed version of the following article: HuR mediates the synergistic effects of angiotensin II and IL-1β on vascular COX-2 expression and cell migration, British Journal of Pharmacology 172.12 (2015): 3028-3042 , which has been published in final form at http://dx.doi.org/10.1111/bph.13103. This article may be used for non-commercial purposes in accordance with Wiley-VCH Terms and Conditions for Self-ArchivingBACKGROUND AND PURPOSE: Angiotensin II (AngII) and interleukin 1β (IL-1β) are involved in cardiovascular diseases through induction of inflammatory pathways. HuR is an ARE-binding protein that contributes to the mRNA stabilization of many genes. This study investigated the contribution of HuR upon COX-2 expression induced by AngII and IL-1β and its consequences on vascular smooth muscle cell (VSMC) migration and remodeling. EXPERIMENTAL APPROACH: Rat and human VSMC stimulated with AngII (0.1 μM) and/or IL-1β (10 ng·mL-1 ) and mice infused with AngII or subjected to carotid artery ligation were used. mRNA and protein levels were assayed by qPCR, western blot, immunohistochemistry, and immunofluorescence. Cell migration was measured by wound healing and transwell assays. KEY RESULTS: In VSMC, AngII potentiated COX-2 and tenascin-C expressions and cell migration induced by IL-1β. The effect of AngII on IL-1β-induced COX-2 expression was accompanied by increased COX-2 3'UTR reporter activity and mRNA stability occurring through cytoplasmic HuR translocation and COX-2 mRNA binding. These effects were blocked by ERK1/2 and HuR inhibitors. VSMC migration was reduced by blockade of ERK1/2, HuR, COX-2, TXAS, TP and EP receptors. HuR, COX-2, mPGES-1 and TXAS expressions were increased in AngII-infused mouse aortas and in carotid-ligated arteries. AngII-induced tenascin-C expression and vascular remodeling were abolished by celecoxib and by mPGES-1 deletion. CONCLUSIONS AND IMPLICATIONS: The synergistic induction of COX-2 by AngII and IL-1β in VSMC involves HuR through an ERK1/2-dependent mechanism. The HuR/COX-2 axis participates in cell migration and vascular damage. HuR might be a novel target to modulate vascular remodeling.This study was supported by MINECO (SAF2012-36400 and SAF2012-40127), ISCIII (RD12/0042/0024, RD12/0042/0053, PI13/01488), Fundación Mutua Madrileña, UAM-Grupo Santander and NIH (R01CA134609). AA and AMB were supported by a FPI fellowship and the Ramón y Cajal program (RYC-2010-06473), respectivel