Loss of Function of von Hippel-Lindau Trigger Lipocalin 2-Dependent Inflammatory Responses in Cultured and Primary Renal Tubular Cells

Previous studies have shown that mutations in the tumor suppressor gene von Hippel-Lindau (VHL) can result in the overproduction of reactive oxygen species (ROS) and chronic inflammation and are a significant predisposing factor for the development of clear-cell renal cell carcinoma (ccRCC). To study VHL’s role in ccRCC formation, we previously developed a novel conditional knockout mouse model that mimicked the features of kidney inflammation and fibrosis that lead to cyst formation and hyperplasia. However, due to VHL’s complex cellular functions, the mechanism of this phenomenon remains unclear. Here, we used the HK-2 cells and mouse primary renal tubule cells (mRTCs) carrying VHL mutations as models to study the effects and underlying molecular mechanisms of ROS accumulation. We also studied the role of lipocalin 2 (LCN2) in regulating macrophage recruitment by HK-2 cells. We measured the level of ROS in HK-2 cells in the presence or absence of LCN2 knockdown and found that the VHL mutation caused ROS overproduction, but an LCN2 knockdown could attenuate the process. VHL was also found to mediate the in vitro and in vivo expression and secretion of LCN2. Thus, VHL likely affects ROS production in an LCN2-dependent manner. Our findings also suggest that LCN2 sensitizes the inflammatory response of HK-2 cells and the chemotactic abilities of macrophage RAW264.7 cells. By demonstrating that the loss of function of von Hippel-Lindau triggers lipocalin 2-dependent inflammatory responses in cultured and primary renal tubular cells, our results offer novel insights into a potential therapeutic approach for interfering with the development of ccRCC.

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HIF-1-mediated production of exosomes during hypoxia is protective in renal tubular cells

AJP Renal Physiology ◽

10.1152/ajprenal.00178.2017 ◽

2017 ◽

Vol 313 (4) ◽

pp. F906-F913 ◽

Cited By ~ 37

Author(s):

Wei Zhang ◽

Xiangjun Zhou ◽

Qisheng Yao ◽

Yutao Liu ◽

Hao Zhang ◽

...

Keyword(s):

Cell Injury ◽

Hypoxia Inducible Factor ◽

Atp Depletion ◽

Tubular Cell ◽

Renal Tubular Cell ◽

Dependent Manner ◽

Protective Effects ◽

Tubular Cells ◽

Renal Tubular Cells ◽

Renal Tubular

Exosomes are nano-sized vesicles produced and secreted by cells to mediate intercellular communication. The production and function of exosomes in kidney tissues and cells remain largely unclear. Hypoxia is a common pathophysiological condition in kidneys. This study was designed to characterize exosome production during hypoxia of rat renal proximal tubular cells (RPTCs), investigate the regulation by hypoxia-inducible factor-1 (HIF-1), and determine the effect of the exosomes on ATP-depletion-induced tubular cell injury. Hypoxia did not change the average sizes of exosomes secreted by RPTCs, but it significantly increased exosome production in a time-dependent manner. HIF-1 induction with dimethyloxalylglycine also promoted exosome secretion, whereas pharmacological and genetic suppression of HIF-1 abrogated the increase of exosome secretion under hypoxia. The exosomes from hypoxic RPTCs had inhibitory effects on apoptosis of RPTCs following ATP depletion. The protective effects were lost in the exosomes from HIF-1α knockdown cells. It is concluded that hypoxia stimulates exosome production and secretion in renal tubular cells. The exosomes from hypoxic cells are protective against renal tubular cell injury. HIF-1 mediates exosome production during hypoxia and contributes to the cytoprotective effect of the exosomes.

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Telmisartan Attenuates Uric Acid-Induced Epithelial-Mesenchymal Transition in Renal Tubular Cells

BioMed Research International ◽

10.1155/2019/3851718 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12 ◽

Cited By ~ 5

Author(s):

Dongqing Zha ◽

Saiqun Wu ◽

Ping Gao ◽

Xiaoyan Wu

Keyword(s):

Uric Acid ◽

Epithelial Cells ◽

Nadph Oxidase ◽

Dependent Manner ◽

Tubular Epithelial Cells ◽

Mesenchymal Transition ◽

Tubular Cells ◽

Renal Tubular Cells ◽

Diphenylene Iodonium ◽

Renal Tubular

We examined whether and how uric acid induces epithelial to mesenchymal transition (EMT) in renal tubular cells, along with the mechanism by which telmisartan acts on uric acid-induced renal injury. Rat renal proximal tubular epithelial cells (NRK-52E) were exposed to various concentrations of uric acid in the presence or absence of telmisartan. Treatment with uric acid increased the expression of α-SMA, decreased the expression of E-cadherin, and promoted EMT in NRK-52E cells. Uric acid treatment also led to increased endothelin-1 (ET-1) production, activation of extracellular-regulated protein kinase 1/2 (ERK1/2), and the upregulation of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4). Use of ET-1 receptor inhibitor (BQ123 or BQ788) could inhibit uric acid-induced EMT in NRK-52E cells. Pretreatment with the ERK inhibitor (U0126 or PD98059) suppressed the release of ET-1 and EMT induced by uric acid. Additionally, pretreatment with a traditional antioxidant (diphenylene iodonium or apocynin) inhibited the activation of ERK1/2, release of ET-1, and uric acid-induced EMT in NRK-52E cells. These findings suggested that uric acid-induced EMT in renal tubular epithelial cells occurs through NADPH oxidase-mediated ERK1/2 activation and the subsequent release of ET-1. Furthermore, telmisartan (102 nmol/L to 104 nmol/L) inhibited the expression of NOX4, intracellular reactive oxygen species (ROS), activation of ERK1/2, and the release of ET-1 in a dose-dependent manner, thereby preventing uric acid-induced EMT in NRK-52E. In conclusion, telmisartan could ameliorate uric acid-induced EMT in NRK-52E cells likely through inhibition of the NADPH oxidase/ERK1/2/ET-1 pathway.

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Naproxen-induced Ca2+ movement and death in MDCK canine renal tubular cells

Human & Experimental Toxicology ◽

10.1177/0960327115569810 ◽

2015 ◽

Vol 34 (11) ◽

pp. 1096-1105

Author(s):

H-H Cheng ◽

C-T Chou ◽

T-K Sun ◽

W-Z Liang ◽

J-S Cheng ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Annexin V ◽

Dependent Manner ◽

Acetoxymethyl Ester ◽

Concentration Dependent Manner ◽

Tubular Cells ◽

Renal Tubular Cells ◽

Renal Tubular ◽

Induced Apoptosis ◽

Darby Canine Kidney

Naproxen is an anti-inflammatory drug that affects cellular calcium ion (Ca2+) homeostasis and viability in different cells. This study explored the effect of naproxen on [Ca2+]i and viability in Madin-Darby canine kidney cells (MDCK) canine renal tubular cells. At concentrations between 50 μM and 300 μM, naproxen induced [Ca2+]i rises in a concentration-dependent manner. This Ca2+ signal was reduced partly when extracellular Ca2+ was removed. The Ca2+ signal was inhibited by a Ca2+ channel blocker nifedipine but not by store-operated Ca2+ channel inhibitors (econazole and SKF96365), a protein kinase C (PKC) activator phorbol 12-myristate 13-acetate, and a PKC inhibitor GF109203X. In Ca2+-free medium, pretreatment with 2,5-di-tert-butylhydroquinone or thapsigargin, an inhibitor of endoplasmic reticulum Ca2+ pumps, partly inhibited naproxen-induced Ca2+ signal. Inhibition of phospholipase C with U73122 did not alter naproxen-evoked [Ca2+]i rises. At concentrations between 15 μM and 30 μM, naproxen killed cells in a concentration-dependent manner, which was not reversed by prechelating cytosolic Ca2+ with the acetoxymethyl ester of 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid acetoxymethyl. Annexin V/propidium iodide staining data suggest that naproxen induced apoptosis. Together, in MDCK renal tubular cells, naproxen induced [Ca2+]i rises by inducing Ca2+ release from multiple stores that included the endoplasmic reticulum and Ca2+ entry via nifedipine-sensitive Ca2+ channels. Naproxen induced cell death that involved apoptosis.

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Autophagy Protects Renal Tubular Cells Against Ischemia / Reperfusion Injury in a Time-Dependent Manner

Cellular Physiology and Biochemistry ◽

10.1159/000374071 ◽

2015 ◽

Vol 36 (1) ◽

pp. 285-298 ◽

Cited By ~ 35

Author(s):

Xuejing Guan ◽

Yingying Qian ◽

Yue Shen ◽

Lulu Zhang ◽

Yi Du ◽

...

Keyword(s):

Cell Apoptosis ◽

Time Course ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Renal Ischemia ◽

Time Dependent ◽

Dependent Manner ◽

Tubular Cells ◽

Renal Tubular Cells ◽

Renal Tubular

Background/Aims: Autophagy is a dynamic catabolic process that maintains cellular homeostasis. Whether it plays a role in promoting cell survival or cell death in the process of renal ischemia/reperfusion (I/R) remains controversial, partly because renal autophagy is usually examined at a certain time point. Therefore, monitoring of the whole time course of autophagy and apoptosis may help better understand the role of autophagy in renal I/R. Methods: Autophagy and apoptosis were detected after mice were subjected to bilateral renal ischemia followed by 0-h to 7-day reperfusion, exposure of TCMK-1 cells to 24-h hypoxia, and 2 to 24-h reoxygenation. The effect of autophagy on apoptosis was assessed in the presence of autophagy inhibitor 3-methyladenine (3-MA) and autophagy activator rapamycin. Results: Earlier than apoptosis, autophagy increased from 2-h reperfusion, reached the maximum at day 2, and then began declining from day 3 when renal damage had nearly recovered to normal. Exposure to 24-h hypoxia induced autophagy markedly, but it decreased drastically after 4 and 8-h reoxygenation, which was accompanied with increased cell apoptosis. Inhibition of autophagy with 3-MA increased the apoptosis of renal tubular cells during I/R in vivo and hypoxia/reoxygenation (H/R) in vitro. In contrast, activation of autophagy by rapamycin significantly alleviated renal tissue damage and tubular cell apoptosis in the two models. Conclusion: Autophagy was induced in a time-dependent manner and occurred earlier than the onset of cell apoptosis as an early response that played a renoprotective role during renal I/R and cell H/R. Up-regulation of autophagy may prove to be a potential strategy for the treatment of acute kidney injury.

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