NF-kappaB P65 DNA Binding Activity Research Articles

Diet‐induced Renal Changes in Zucker Rats Are Ameliorated by the Superoxide Dismutase Mimetic TEMPOL

Diabetic nephropathy is the leading cause of renal failure in the United States. The obese Zucker rat (OZR; fa/fa) is a commonly used model of type 2 diabetes and metabolic syndrome (MetS), and of the nephropathy and renal oxidative stress commonly seen in these disorders. Heterozygous lean Zucker rats (LZRs; fa/+) are susceptible to high-fat diet (HFD)-induced obesity and MetS. The present study was designed to investigate whether 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL), a membrane-permeable radical scavenger, could alleviate the renal effects of MetS in OZR and LZR fed a HFD, which resembles the typical "Western" diet. OZR and LZR were fed a HFD (OZR-HFD and LZR-HFD) or regular diet (OZR-RD and LZR-RD) and allowed free access to drinking water or water containing 1 mmol/l TEMPOL for 10 weeks. When compared to OZR-RD animals, OZR-HFD animals exhibited significantly higher levels of total renal cortical reactive oxygen species (ROS) production, plasma lipids, insulin, C-reactive protein, blood urea nitrogen (BUN), creatinine (Cr), and urinary albumin excretion (P < 0.05); these changes were accompanied by a significant decrease in plasma high-density lipoprotein levels (P < 0.05). The mRNA expression levels of desmin, tumor necrosis factor-alpha (TNF-alpha), nuclear factor kappaB (NFkappaB), and NAD(P)H oxidase-1 (NOX-1) were significantly higher in the renal cortical tissues of OZR-HFD animals; NFkappaB p65 DNA binding activity as determined by electrophoretic mobility shift assay was also significantly higher in these animals. The same trends were noted in LZR-HFD animals. Our data demonstrate that TEMPOL may prove beneficial in treating the early stages of the nephropathy often associated with MetS.

Effects of early insulin therapy on nuclear factor kappaB pathway in skeletal muscle of diabetes: experiment with rats

To investigate the effect of early insulin therapy on the nuclear factor kappaB (NF-kappaB) pathway and inflammatory cytokine responses in skeletal muscle in type 2 diabetes mellitus (DM). SD rats underwent intraperitoneal injection of streptozotocin to establish DM models and then divided into 5 groups: early un-treated group, early gliclazide treated group (receiving gliclazide since the third day after blood glucose increase for 3 weeks for 3 weeks), early insulin treated group (receiving insulin since the third day after blood glucose increase for 3 weeks for 3 weeks), late un-treated group, and late insulin treated group (receiving insulin since the fourth week after blood glucose increase for 3 weeks). By the end of treatment the rats were killed. Homogenate of skeletal muscle was made. The NF-kappaB P65 DNA binding was assayed by ELISA-based assay kit. Real time PCR was used to detect the mRNA expression levels of the gene of the cytokines: glucose transporter 4 (Glut4), inhibitor kappaB (IkappaBalpha), IL-1beta, IL-6, and tumor necrosis factor (TNF)-alpha. And Glut4 and IkappaBalpha protein expression levels were assayed by Western blotting. The Glut4 mRNA level in the skeletal muscle of the untreated DM rats decreased by 59% and the Glut4 protein level in the muscle cell membrane decreased by 69%. Insulin treatment and gliclazide treatment increased the Glut4 mRNA expression by 17% and 13% respectively, increased the Glut4 protein expression in cell membrane by 23% and 10% respectively, and decreased the Glut4 protein expression in the cytoplasm. In the DM rats the IkappaBalpha protein expression in the skeletal muscle was significantly lower (P < 0.05) and the NF-kappaB P65 DNA binding activity increased, and TNF-alpha, IL-1B, and IL-6 expression levels were up-regulated in comparison with the normal control group. Early treatment of insulin and gliclazide increased the IkappaBalpha protein expression, decreased the NF-kappaB P65 DNA binding activity and the TNF-alpha expression in the skeletal muscle. Early insulin treatment inhibits the NFkappaB activity and inflammatory cytokine responses in skeletal muscle that are involved in the amelioration of insulin resistance in type 2 DM. Such results may be due to indirect antiinflammatory effects of insulin relieving glucotoxicity and lipotoxicity in peripheral tissues.

Effect of early insulin therapy on nuclear factor κB and cytokine gene expressions in the liver and skeletal muscle of high-fat diet, streptozotocin-treated diabetic rats

To clarify the effect of early insulin therapy on nuclear factor kappaB (NFkappaB) pathway and inflammatory cytokine responses in the liver and skeletal muscle in type 2 diabetes. High-fat diet and low dose streptozotocin (STZ) induced diabetic rats were given NPH insulin or gliclazide for 3 weeks initiated at the 3rd day after STZ injection as early treatment and NPH for 3 weeks at 1 month as late treatment. Intraperitoneal glucose tolerance test (IPGTT) was performed at 3rd day after the end of treatment. Early interventions caused a decrease in glucose-insulin index in IPGTT, promoted glucose transporter 4 (Glut4) gene and protein expressions in muscle and reduced phosphoenolpyruvate carboxykinase (PEPCK) protein levels in the liver. There was an increase in inhibitor kappaB (IkappaBalpha) protein and a decrease in NFkappaB p65 DNA binding activity. A decreased level in mRNAs encoding tumor necrosis factor (TNF)alpha in the liver and muscle and interleukin (IL)-1beta in the liver were observed. Our results suggested that early insulin treatment inhibits NFkappaB activity and inflammatory cytokine responses in the liver and skeletal muscle that were involved in the amelioration of insulin resistance in type 2 diabetic rats.

Angiopoietin 1 directly induces destruction of the rheumatoid joint by cooperative, but independent, signaling via ERK/MAPK and phosphatidylinositol 3-kinase/Akt

To determine whether angiopoietin 1 (Ang-1) potentiates overgrowth of the synovium and joint degradation in rheumatoid arthritis (RA), and to clarify the cell-signaling mechanisms of Ang-1 in the rheumatoid joint. Expression of Ang-1, TIE-2 (a receptor for Ang-1), and matrix metalloproteinase 3 (MMP-3) was studied by immunohistochemistry. Activation of the ERK/MAPK and phosphatidylinositol (PI) 3-kinase/Akt pathways and of NF-kappaB was determined by Western blotting and an NF-kappaB p65 DNA binding activity assay, respectively. Induction of apoptosis was evaluated by nuclear staining, cell viability assay, and Western blotting of caspases. Synovial cell migration was evaluated by actin polymerization, Western blotting of Rho family proteins, and affinity purification with Rhotekin-Rho and p21-activated kinase 1. Matrix degradation was examined by induction of proMMP-3 secretion from synovial cells followed by in vitro cartilaginous matrix degradation assay. Ang-1 stimulated the ERK/MAPK and PI 3-kinase/Akt pathways in a cooperative but independent manner, which enhanced rheumatoid synovium overgrowth and joint destruction. In addition, Ang-1 activated NF-kappaB via Akt to promote cell growth, but also inhibited cell apoptosis via ERK and Akt. Ang-1 directly potentiated the extension of synovial cells in an ERK- and Akt-dependent manner by up-regulating Rho family proteins, which attenuated Rac signaling and led to membrane ruffling. Ang-1 induced proMMP-3 secretion from synovial cells, which resulted in direct degradation of the cartilaginous matrix. Ang-1 stimulates the ERK/MAPK and PI 3-kinase/Akt pathways cooperatively, but in a manner independent of each other, to directly potentiate synovium overgrowth and joint destruction in RA. In addition to inflammatory cytokines, Ang-1/TIE-2 signaling appears to be an independent factor that contributes to the destruction of the rheumatoid joint.

Inflammation and postinfarct remodeling: Overexpression of IκB prevents ventricular dilation via increasing TIMP levels

Nuclear factor-kappa B (NF-kappaB) orchestrates genes involved in inflammation and extracellular matrix (ECM) remodeling following myocardial infarction (MI). The objective of the present study was to investigate the effect of overexpression and mode of function of IkappaB, the natural inhibitor of NF-kappaB, on ECM remodeling in a rat model of MI. MI was induced in male Sprague-Dawley rats by ligation of the left anterior descending coronary artery (LAD) and was followed by adenovirus-mediated intramyocardial transfection of IkappaB (n = 26) or LacZ reporter genes (n = 26). Sham-operated animals (n = 14) served as controls. In transthoracic echocardiography 49 days after MI, systolic and diastolic left ventricular dimensions were reduced while fractional shortening was preserved in the treatment group. Additionally, evaluation on the isolated heart showed an attenuated downward shift of pressure-volume relationships in the IkappaB group compared to LacZ. NF-kappaB p65 DNA binding activity was diminished both at 5 and 49 days post-MI in the treatment group. Five days post-MI in the treatment group, protein levels of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta were significantly reduced by 72.6% and 73.2%, respectively, compared to LacZ (p<0.05). In parallel, matrix metalloproteinase (MMP)-2 and MMP-9 levels were reduced 5 days post-MI, with MMP-9 still being decreased 49 days post-MI (p<0.01). In contrast, tissue inhibitors of metalloproteinases (TIMP)-1, -2, and -3 were increased compared to LacZ (p<0.01 and p<0.05, respectively) 5 days post-MI. After 49 days, TIMP-2, -3, and -4 expressions were significantly elevated (p<0.05). Reducing NF-kappaB activity via IkappaB overexpression after MI positively influences ECM remodeling by reducing MMP-2 and -9 levels while increasing TIMP-1, -2, -3, and -4 levels. Therefore, IkappaB overexpression prevents ventricular dilation and consequently preserves cardiac function.