The role of autophagy in unilateral ureteral obstruction rat model
Department of Anatomy and MRC for Cell Death Disease Research Center, Bucheon Saint Mary’s Hospital, Sosa-dong, Wonmi-gu, Bucheon-si, Geoynggi-do, 420-717 Korea. Nephrology
(Impact Factor: 2.08).
11/2011; 17(2):148-59. DOI: 10.1111/j.1440-1797.2011.01541.x
Autophagy is a cellular process of degradation of damaged cytoplasmic components and regulates cell death or proliferation. Unilateral ureteral obstruction (UUO) is a model of progressive renal fibrosis in the obstructed kidney. And UUO is followed by compensatory cellular proliferation in the contralateral kidney. We investigate the role of autophagy in the obstructed kidney and contralateral kidney after UUO.
To obtain the evidence and the patterns of autophagy during UUO, the rats were sacrificed 3, 7 and 14 days after UUO. To examine the efficacy of the autophagy inhibitors, 3-methyladenine (3-MA), the rats were treated daily with intraperitoneal injection of 3-MA (30 mg/kg per day) for 7 days.
After UUO, autophagy was induced in the obstructed kidney in a time-dependent manner. Inhibition of autophagy by 3-MA enhanced tubular cell apoptosis and tubulointerstitial fibrosis in the obstructed kidney after UUO. In the contralateral kidney, autophagy was also induced and prolonged during UUO. Inhibition of autophagy by 3-MA increased the protein expression of proliferating cell nuclear antigen significantly in the contralateral kidney after UUO. The Akt-mammalian target of rapamycin (mTOR) signalling pathway was involved in the induction of autophagy after UUO in both kidneys.
Our present results support that autophagy induced by UUO has a renoprotective role in the obstructed kidney and regulatory role of compensatory cellular proliferation in the contralateral kidney through Akt-mTOR signalling pathway.
Available from: Byoung Kuk Jang
- "However, a growing body of evidence supports the hypothesis that autophagy has a protective effect against fibrosis in various tissues  . Autophagy in the kidney plays a cytoprotective role by promoting intracellular degradation of type 1 collagen in response to TGF-b without altering the type I collagen mRNA level , and provides protection against tubular cell apoptosis and tubulointerstitial fibrosis after unilateral urethral obstruction . However, Hernadez-Gea et al. reported that autophagy induced fibrogenesis in mouse mesangial cell as well as in HSCs . "
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ABSTRACT: Hepatic stellate cells (HSCs) are major players in liver fibrogenesis. Accumulating evidence shows that suppression of autophagy plays an important role in the development and progression of liver disease. Phospholipase D1 (PLD1), which catalyzes the hydrolysis of phosphatidylcholine to yield phosphatidic acid (PA) and choline, was recently shown to modulate autophagy. However, little is known about the effects of PLD1 on the production of type I collagen that characterizes liver fibrosis. Here, we examined whether PLD1 regulates type I collagen levels in HSCs through induction of autophagy. Adenovirus-mediated overexpression of PLD-1 (Ad-PLD1) reduced type I collagen levels in the activated human HSC lines, hTERT and LX2. Overexpression of PLD1 in HSCs led to induction of autophagy as demonstrated by increased LC3-II conversion and formation of LC3 puncta, and decreased p62 abundance. Moreover, inhibiting the induction of autophagy by treating cells with bafilomycin or a small interfering (si)RNA for ATG7 rescued Ad-PLD1-induced suppression of type I collagen accumulation in HSCs. The effects of PLD on type I collagen levels were not related to TGF-β/Smad signaling. Furthermore, treatment of cells with PA induced autophagy and inhibited type I collagen accumulation. The present study indicates that PLD1 plays a role in regulating type I collagen accumulation through induction of autophagy.
Available from: PubMed Central
- "Unilateral ureteral obstruction (UUO) is a classical model of progressive renal fibrosis. Autophagy is induced in obstructed kidney after UUO induction, and inhibition of autophagy by 3-MA enhances tubulointerstitial fibrosis, indicating a renoprotective role of autophagy in renal fibrosis [31, 32]. In a TGF-beta overexpression transgenic mouse model which exhibits widespread peritubular fibrosis, tubular cells decomposition is induced by autophagy . "
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ABSTRACT: Hepatic fibrosis is a leading cause of morbidity and mortality worldwide. Hepatic fibrosis is usually associated with chronic liver diseases caused by infection, drugs, metabolic disorders, or autoimmune imbalances. Effective clinical therapies are still lacking. Autophagy is a cellular process that degrades damaged organelles or protein aggregation, which participates in many pathological processes including liver diseases. Autophagy participates in hepatic fibrosis by activating hepatic stellate cells and may participate as well through influencing other fibrogenic cells. Besides that, autophagy can induce some liver diseases to develop while it may play a protective role in hepatocellular abnormal aggregates related liver diseases and reduces fibrosis. With a better understanding of the potential effects of autophagy on hepatic fibrosis, targeting autophagy might be a novel therapeutic strategy for hepatic fibrosis in the near future.
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ABSTRACT: We recently reported that necrotic renal proximal tubular cells (RPTC) can induce the death of renal interstitial fibroblasts. Since autophagy plays either cytoprotective or cytodestructive roles depending on the experimental condition, the present study was carried out to investigate whether necrotic RPTC would induce autophagy of renal interstitial fibroblasts and, if so, whether autophagy would contribute to cell death or exert a protective effect. Exposure of necrotic RPTC supernatant (RPTC-Sup) induced autophagy in renal interstitial fibroblast cells (NRK-49F) in a time- and dose-dependent manner, and its induction was earlier than caspase-3 activation. Inhibition of autophagy with 3-methyladenine (3-MA) or knockdown of Beclin-1, a molecule involved in the initiation of autophagosome formation, with small interference RNA (siRNA) significantly enhanced necrotic RPTC-Sup-induced cell death. Necrotic RPTC-Sup induced phosphorylation of extracellular signal-regulated kinases (ERK1/2), p38, c-Jun NH(2)-terminal kinases (JNKs), and AKT. Treatment with an ERK1/2 pathway inhibitor, but not with specific inhibitors for p38, JNKs, or AKT pathways, blocked NRK-49F autophagy and cell death upon exposure to necrotic RPTC-Sup. Furthermore, knockdown of MEK1 with siRNA also reduced autophagy along with cell death in NRK-49F exposed to necrotic RPTC-Sup. In contrast, overexpression of MEK1/2 increased RPTC-Sup-induced fibroblast cell death without enhancing autophagy. Collectively, this study demonstrates that necrotic RPTC induce both autophagy and cell death and that autophagy plays a cytoprotective or prosurvival role in renal fibroblasts. Furthermore, necrotic RPTC-induced autophagy and cell death in renal fibroblasts is mediated by the activation of the MEK1-ERK1/2 signaling pathway.
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