High glucose induces renal tubular epithelial injury via Sirt1/NF-kappaB/microR-29/Keap1 signal pathway
Zhou et al. J Transl Med
High glucose induces renal tubular epithelial injury via Sirt1/NF-kappaB/microR-29/ Keap1 signal pathway
Ling Zhou 3
Dey‑u Xu 3
Wen‑gang Sha 3
Lei Shen 3
Guoy‑uan Lu 3
Xia Yin 2
Ming‑jun Wang 0 1
0 Department of Rheumatology, The First Affiliated Hospital of Soochow University , 188 shizi Rd., Suzhou 215006 , People's Republic of China
1 Department of Rheu‐ matology, The First Affiliated Hospital of Soochow University , 188 shizi Rd., Suzhou 215006 , People's Republic of China
2 Department of Endocrinology, The First Affiliated Hospital of Soochow University , Suzhou 215006 , China
3 Department of Nephrology, The First Affiliated Hospital of Soochow Univer‐ sity , Suzhou 215006 , China
Objective: Diabetic nephropathy (DN) is a serious complication that commonly confronted by diabetic patients. A common theory for the pathogenesis of this renal dysfunction in diabetes is cell injury, inflammation as well as oxidative stress. In this content, the detailed molecular mechanism underlying high glucose induced renal tubular epithelial injury was elaborated. Methods: An in vivo rat model of diabetes by injecting streptozotocin (STZ) and an in vitro high glucose incubated renal tubular epithelial cell (HK‑ 2) model were used. Expression levels of Keap1, nuclear Nrf2 and p65 were determined by western blotting. Level of microR‑ 29 (miR‑ 29) was assessed using quantitative RT‑ PCR. Combination of p65 and miR‑ 29 promotor was assessed using chromatin immunoprecipitation. Keap1 3′‑ UTR activity was detected using luciferase reporter gene assay. Cell viability was determined using MTT assay. Results: In diabetic rat, miR‑ 29 was downregulated and its expression is negatively correlated with both of serum creatinine and creatinine clearance. In high glucose incubated HK‑ 2 cell, deacetylases activity of Sirt1 was attenuated that leads to decreased activity of nuclear factor kappa B (NF‑ κB). NF‑ κB was demonstrated to regulate miR‑ 29 expression by directly binding to its promotor. The data of luciferase assay showed that miR‑ 29 directly targets to Keap1 mRNA. While high glucose induced down regulation of miR‑ 29 contributed to enhancement of Keap1 expression that finally reduced Nrf2 content by ubiquitinating Nrf2. Additionally, overexpression of miR‑ 29 effectively relieved high glucose‑ reduced cell viability. Conclusion: High glucose induces renal tubular epithelial injury via Sirt1/NF‑ κB/microR‑ 29/Keap1 signal pathway.
Acetyl‑ p65; HK‑ 2; miR‑ 29; Nrf2; Serum creatinine
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Background
Diabetes mellitus is a common metabolic disorder which
is associated with chronic complications such as
angiopathy, retinopathy, and peripheral neuropathy. It was
recognized that diabetes also can lead to
nephropathy. Since then, studies in experimental models and in
patients observed structural abnormalities in vascular
and glomerular [1]. However, tubular cells are proved to
be primary targets of hyperglycemia which is the major
cause for renal injury and previous evidence indicated
that chronic exposure to elevated blood glucose levels
contributes to the organic pathologic changes in
clinical diabetes nephropathy (DN) [2, 3]. Thus searching for
therapy targets might be benefit for concurrency of DN.
In previous study, high glucose induced inflammatory
response as well as activated inflammation related signal
pathway. Sirt1, a class III histone deacetylase, is
recognized as an important regulator in many high
glucoserelated inflammatory diseases [4]. For example, Sirt1
activator blunting pro-inflammatory pathways in mice
fed a high fat, high calorie diet [5]. Especially, Sirt1 and
its modulation of the acetylation status of the p65 subunit
of nuclear factor kappa B (NF-κB) play an important role
in regulating the inflammatory and apoptotic responses
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in cells or tissues [6]. As an essential nuclear
transcription factor, NF-κB is commonly activated by wide
variety of cell-tress stimuli including obesity, oxidative stress,
as well as stimulated by hyperglycemia. Accumulated
evidence pointed out that NF-κB was upregulated in
diabetic rat kidneys [7] and its inhibition contributed to
significant amelioration of DN [8]. Although
observation has showed that master regulator of inflammation
of NF-κB is essential for pathological process of DN, the
detailed downstream intracellular signal transduction is
not yet clear.
MicroRN (...truncated)