Chronic dysregulation of metabolism is the hallmark of type 2 diabetes. Hyperinsulinemia and insulin resistance are often observed in conjunction with additional risk factors, including obesity, atherogenic dyslipidemia, hyperglycemia, hypertension, and a pro-thrombotic and pro-inflammatory state, which together, characterize the """"""""metabolic syndrome"""""""". Our research group has focused on NF-?B activation in type 2 diabetes, and we and others have identified 3 mechanisms leading to activation of NF-?B. First, we have reported increased expression of numerous NF-?B-regulated pro-inflammatory cytokines, chemokines, and growth factors in the renal cortex of db/db mice, indicating a dysregulated and prolonged activation of the NF-?B canonical pathway. Second, we have reported that diabetes alters NF-?B noncanonical pathway proteins in renal cortex, and we have localized these proteins to renal proximal tubular epithelial cells (pTEC). Third, we have identified another alternative pathway of NF-?B activation that involves phosphorylation of RelA serine536. Based on our animal studies, we postulate that diabetes activates both canonical and noncanonical NF-?B pathways, leading to renal inflammation. Since NF-?B activation is rapidly arrested, an important, unanswered question is why this does not occur in diabetic tissues, where canonical pathway activation of the innate immune response persists chronically. We hypothesize that diabetes-induced activation of NF-?B noncanonical pathways plays a causal role in prolonging the innate immune response activated by the canonical pathway, contributing significantly to the progression of complications. In order to test this hypothesis, we will use a human pTEC tissue culture system to probe molecular mechanisms involved in canonical vs. noncanonical NF- ?B pathway activation in response to stimuli that mimic the in vivo diabetic milieu.
In Aim 1, we will identify the time-dependent activation profile of the two NF-?B pathways in human pTEC exposed to elevated glucose, advanced glycated endproducts (AGE), and angiotensin-II (Ang-II) using NF-?B pathway-specific reporter-gene assays.
In Aim 2, we will explore the role of NIK in NF-?B noncanonical pathway activation induced by glucose, AGE and Ang-II by employing NIK-specific siRNA and by overexpressing NIK-wild type or kinase-dead, dominant-negative NIK mutants.
Aim 3 will characterize the activation kinetics and nuclear processing of RelB in human renal pTEC, and Aim 4 will determine the significance of RelA phosphorylation on serine536 as another alternative noncanonical NF-kB pathway signaling mechanism in pTEC. The results obtained from the proposed aims will provide invaluable insights into molecular mechanisms by which diabetes induces and maintains chronic inflammation in the kidney.

Public Health Relevance

Our research group has focused on the role of inflammation and NF-?B activation in the pathogenesis of diabetic nephropathy in type 2 diabetes. Using human proximal tubular epithelial cells in tissue culture, together with in vivo manipulation of NF-?B proteins, we are exploring an important, unanswered question - why is NF-?B canonical pathway activation not rapidly arrested in diabetic tissues, where NF-?B activation of the innate immune response persists chronically. Results of this research have the potential to identify novel therapeutic targets to treat diabetic nephropathy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK079053-02
Application #
7591234
Study Section
Pathobiology of Kidney Disease Study Section (PBKD)
Program Officer
Rys-Sikora, Krystyna E
Project Start
2008-04-01
Project End
2012-03-31
Budget Start
2009-04-01
Budget End
2010-03-31
Support Year
2
Fiscal Year
2009
Total Cost
$320,875
Indirect Cost
Name
University of Texas Medical Br Galveston
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
800771149
City
Galveston
State
TX
Country
United States
Zip Code
77555
Ju, Xiaoxi; Ijaz, Talha; Sun, Hong et al. (2014) IL-6 regulates extracellular matrix remodeling associated with aortic dilation in a fibrillin-1 hypomorphic mgR/mgR mouse model of severe Marfan syndrome. J Am Heart Assoc 3:e000476
Ju, Xiaoxi; Ijaz, Talha; Sun, Hong et al. (2013) Interleukin-6-signal transducer and activator of transcription-3 signaling mediates aortic dissections induced by angiotensin II via the T-helper lymphocyte 17-interleukin 17 axis in C57BL/6 mice. Arterioscler Thromb Vasc Biol 33:1612-21
Banerjee, Srijita; Zhao, Yanhua; Sarkar, Partha S et al. (2013) Klotho ameliorates chemically induced endoplasmic reticulum (ER) stress signaling. Cell Physiol Biochem 31:659-72
Choudhary, Sanjeev; Kalita, Mridul; Fang, Ling et al. (2013) Inducible tumor necrosis factor (TNF) receptor-associated factor-1 expression couples the canonical to the non-canonical NF-?B pathway in TNF stimulation. J Biol Chem 288:14612-23
Starkey, Jonathan M; Tilton, Ronald G (2012) Proteomics and systems biology for understanding diabetic nephropathy. J Cardiovasc Transl Res 5:479-90
Choudhary, Sanjeev; Sinha, Sandeep; Zhao, Yanhua et al. (2011) NF-kappaB-inducing kinase (NIK) mediates skeletal muscle insulin resistance: blockade by adiponectin. Endocrinology 152:3622-7
Zhao, Yanhua; Banerjee, Srijita; Dey, Nilay et al. (2011) Klotho depletion contributes to increased inflammation in kidney of the db/db mouse model of diabetes via RelA (serine)536 phosphorylation. Diabetes 60:1907-16
Tieu, Brian C; Ju, Xiaoxi; Lee, Chang et al. (2011) Aortic adventitial fibroblasts participate in angiotensin-induced vascular wall inflammation and remodeling. J Vasc Res 48:261-72
Zhao, Yanhua; Banerjee, Srijita; LeJeune, Wanda S et al. (2011) NF-ýýB-inducing kinase increases renal tubule epithelial inflammation associated with diabetes. Exp Diabetes Res 2011:192564
Choudhary, Sanjeev; Rosenblatt, Kevin P; Fang, Ling et al. (2011) High throughput short interfering RNA (siRNA) screening of the human kinome identifies novel kinases controlling the canonical nuclear factor-?B (NF-?B) activation pathway. J Biol Chem 286:37187-95

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