Dataset Information

Contractile protein expression is upregulated by reactive oxygen species in aorta of Goto-Kakizaki rat.

ABSTRACT: Although it is known that blood vessels undergo remodeling in type 2 diabetes (T2D), the signaling pathways that underlie the structural and functional changes seen in diabetic arteries remain unclear. Our objective was to determine whether the remodeling in type 2 diabetic Goto-Kakizaki (GK) rats is evoked by elevated reactive oxygen species (ROS). Our results show that aortas from GK rats produced greater force (P < 0.05) in response to stimulation with KCl and U46619 than aortas from Wistar rats. Associated with these changes, aortic expression of contractile proteins (measured as an index of remodeling) and the microRNA (miR-145), which act to upregulate transcription of contractile protein genes, was twofold higher (P < 0.05) in GK than Wistar (age-matched control) rats, and there was a corresponding increase in ROS and decrease in nitric oxide signaling. Oral administration of the antioxidant Tempol (1 mmol/l) to Wistar and GK rats reduced (P < 0.05) myocardin and calponin expression. Tempol (1 mmol/l) decreased expression of miR-145 in Wistar and GK rat aorta. To elucidate the mechanism through which ROS increases miR-145, we measured their levels in freshly isolated aorta and cultured aortic smooth muscle cells incubated for 12 h in the presence of H2O2 (300 ?mol/l). H2O2 increased expression of miR-145, and there were corresponding nuclear increases in myocardin, a miR-145 target protein. Intriguingly, H2O2-induced expression of miR-145 was decreased by U0126 (10 ?mol/l), a MEK1/2 inhibitor, and myocardin was decreased by anti-miR-145 (50 nmol/l) and U0126 (10 ?mol/l). Our novel findings demonstrate that ROS evokes vascular wall remodeling and dysfunction by enhancing expression of contractile proteins in T2D.

SUBMITTER: Chettimada S

PROVIDER: S-EPMC3920128 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Contractile protein expression is upregulated by reactive oxygen species in aorta of Goto-Kakizaki rat.

Chettimada Sukrutha S Ata Hirotaka H Rawat Dhwajbahadur K DK Gulati Salil S Kahn Andrea G AG Edwards John G JG Gupte Sachin A SA

American journal of physiology. Heart and circulatory physiology 20131108 2

Although it is known that blood vessels undergo remodeling in type 2 diabetes (T2D), the signaling pathways that underlie the structural and functional changes seen in diabetic arteries remain unclear. Our objective was to determine whether the remodeling in type 2 diabetic Goto-Kakizaki (GK) rats is evoked by elevated reactive oxygen species (ROS). Our results show that aortas from GK rats produced greater force (P < 0.05) in response to stimulation with KCl and U46619 than aortas from Wistar r ...[more]

PMID: 24213617

Similar Datasets

Project description:BackgroundPatients with diabetes are at a high risk for developing cardiac dysfunction in the absence of coronary artery disease or hypertension, a condition known as diabetic cardiomyopathy. Contributing to heart failure is the presence of diabetic kidney disease. The Goto-Kakizaki (GK) rat is a non-obese, non-hypertensive model of type 2 diabetes that, like humans, shares a susceptibility locus on chromosome 10. Herein, we perform a detailed analysis of cardio-renal remodeling and response to renin angiotensin system blockade in GK rats to ascertain the validity of this model for further insights into disease pathogenesis.MethodsStudy 1: Male GK rats along with age matched Wistar control animals underwent longitudinal assessment of cardiac and renal function for 32 weeks (total age 48 weeks). Animals underwent regular echocardiography every 4 weeks and at sacrifice, early (~24 weeks) and late (~48 weeks) timepoints, along with pressure volume loop analysis. Histological and molecular characteristics were determined using standard techniques. Study 2: the effect of renin angiotensin system (RAS) blockade upon cardiac and renal function was assessed in GK rats. Finally, proteomic studies were conducted in vivo and in vitro to identify novel pathways involved in remodeling responses.ResultsGK rats developed hyperglycaemia by 12 weeks of age (p<0.01 c/w Wistar controls). Echocardiographic assessment of cardiac function demonstrated preserved systolic function by 48 weeks of age. Invasive studies demonstrated left ventricular hypertrophy, pulmonary congestion and impaired diastolic function. Renal function was preserved with evidence of hyperfiltration. Cardiac histological analysis demonstrated myocyte hypertrophy (p<0.05) with evidence of significant interstitial fibrosis (p<0.05). RT qPCR demonstrated activation of the fetal gene program, consistent with cellular hypertrophy. RAS blockade resulted in a reduction blood pressure(P<0.05) cardiac interstitial fibrosis (p<0.05) and activation of fetal gene program. No significant change on either systolic or diastolic function was observed, along with minimal impact upon renal structure or function. Proteomic studies demonstrated significant changes in proteins involved in oxidative phosp4horylation, mitochondrial dysfunction, beta-oxidation, and PI3K/Akt signalling (all p<0.05). Further, similar changes were observed in both LV samples from GK rats and H9C2 cells incubated in high glucose media.ConclusionBy 48 weeks of age, the diabetic GK rat demonstrates evidence of preserved systolic function and impaired relaxation, along with cardiac hypertrophy, in the presence of hyperfiltration and elevated protein excretion. These findings suggest the GK rat demonstrates some, but not all features of diabetes induced "cardiorenal" syndrome. This has implications for the use of this model to assess preclinical strategies to treat cardiorenal disease.

Project description:BackgroundThe Goto-Kakizaki (GK) rat is a well-studied non-obese spontaneous type 2 diabetes (T2D) animal model characterized by impaired glucose-stimulated insulin secretion (GSIS) in the pancreatic beta cells. MicroRNAs (miRNAs) are short regulatory RNAs involved in many fundamental biological processes. We aim to identify miRNAs that are differentially-expressed in the pancreatic islets of the GK rats and investigate both their short- and long term glucose-dependence during glucose-stimulatory conditions.Methodology/principal findingsGlobal profiling of 348 miRNAs in the islets of GK rats and Wistar controls (females, 60 days, N = 6 for both sets) using locked nucleic acid (LNA)-based microarrays allowed for the clear separation of the two groups. Significant analysis of microarrays (SAM) identified 30 differentially-expressed miRNAs, 24 of which are predominantly upregulated in the GK rat islets. Monitoring of qPCR-validated miRNAs during GSIS experiments on isolated islets showed disparate expression trajectories between GK and controls indicating distinct short- and long-term glucose dependence. We specifically found expression of rno-miR-130a, rno-miR-132, rno-miR-212 and rno-miR-335 to be regulated by hyperglycaemia. The putative targets of upregulated miRNAs in the GK, filtered with glucose-regulated mRNAs, were found to be enriched for insulin-secretion genes known to be downregulated in T2D patients. Finally, the binding of rno-miR-335 to a fragment of the 3'UTR of one of known down-regulated exocytotic genes in GK islets, Stxbp1 was shown by luciferase assay.Conclusions/significanceThe perturbed miRNA network found in the GK rat islets is indicative of a system-wide impairment in the regulation of genes important for the normal functions of pancreatic islets, particularly in processes involving insulin secretion during glucose stimulatory conditions. Our findings suggest that the reduced insulin secretion observed in the GK rat may be partly due to upregulated miRNA expression leading to decreased production of key proteins of the insulin exocytotic machinery.

Dataset Information

Contractile protein expression is upregulated by reactive oxygen species in aorta of Goto-Kakizaki rat.

Publications

Contractile protein expression is upregulated by reactive oxygen species in aorta of Goto-Kakizaki rat.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets