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Objective To evaluate the effect of over-expression of phosphatase and tensin homolog does on chromosome ten (PTEN) in podocytes on kidney under high fat diet (HFD) in vivo and clarify the mechanism how PTEN regulates scavenger receptor A (SR-A) expression exposed to oxidized low density lipoprotein (ox-LDL) in podocytes in vitro.Methods The podocyte-specific PTEN knockin (PPKI) mice were fed with HFD to establish mouse model of lipid-induced renal injury.Mice were divided into four groups:ND+Ctrl group,ND+PPKI group,HFD+Ctrl group and HFD+PPKI group.After 24 weeks of dietary intervention,all mice were tested for clinical and biochemical parameters,including serum creatinine (Scr) as well as urine albumin excretion rate (UAER);renal lipid content was measured by oil red O staining and cholesterol quantitative analysis;the pathological changes of glomeruli were observed by PAS staining and electron microscope.Podocyte injury was induced by ox-LDL in vitro.Western blotting was used to detect the changes of SR-A expression induced by ox-LDL after YAP-siRNA interfering (si-YAP),as well as YAP phosphorylation induced by ox-LDL after interfering by PTEN-siRNA (si-PTEN) and PTEN phosphatase inhibitor (Bpv-PTEN),and overexpressing by recombinant adenovirus (ad-PTEN).Results Compared with ND+Ctrl group,HFD+ Ctrl group significantly aggravated the levels of Scr and UAER,the expression of SR-A in podocytes,renal lipid content,mesangial matrix expansion,effacement of podocyte foot processes,and incrassation of glomerular basement membrane (all P ＜ 0.05).Conversely,compared with HFD+Ctrl group,HFD+ PPKI group obviously alleviated the above lipid-induced renal damage (all P ＜ 0.05).In vitro,the expression of SR-A in podocytes was up-regulated when stimulated with ox-LDL (P ＜ 0.05),and the knockout of YAP significantly down-regulated the expression of SR-A induced by ox-LDL (P ＜ 0.05).Exposed to ox-LDL,the expression of p-YAP increased in podocytes (P ＜ 0.05);over-expression of PTEN inhibited p-YAP up-regulation induced by ox-LDL (P ＜ 0.05),while either knockdown of PTEN or inhibition of PTEN phosphatase activity displayed opposite effect (all P ＜ 0.05).Conclusions Over-expression of PTEN in podocytes protected the kidney against damage from HFD in vivo and PTEN might suppress SR-A mediated lipid uptake via dephosphorylating p-YAP to prevent podocyte injury from ox-LDL.
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Objective@#To explore the role of ROCK1 in oxidized low-density lipoprotein (ox-LDL) induced podocyte injury and its possible mechanism.@*Methods@#The conditionally immortalized mouse podocyte cells were cultured in vitro and exposed to 20 μg/ml ox-LDL for 24 h. Western blotting was used to analyze the expression level of p-MYPT, nephrin, LC3-Ⅱ, p62, p-ULK1 in groups of control, ox-LDL, ROCK1 siRNA with ox-LDL, wtROCK1 with ox-LDL. Podocytes were incubated with DiI labeled ox-LDL for 4 h and fluorescence microscope was used to analyze lipid distribution.@*Results@#Compared with control group, ox-LDL increased cell cholesterol accumulation, activated ROCK along with decreased nephrin, LC3-Ⅱ(P<0.05), and increased p62, and p-ULK1 expression (P<0.05). Over-expression of ROCK1 significantly decreased the expression of nephrin and LC3-Ⅱ, but up-regulated the levels of p62, p-ULK1 and cell cholesterol accumulation in ox-LDL stimulated podocytes (P<0.05). In contrast, Inhibition of ROCK1 protected podocyte by improved lipophagy.@*Conclusion@#ROCK1 mediated disfunction of lipophagy contributes to the ox-LDL induced podocyte injury.
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Objective To compare the diuretic efficacy of torasemide as a 2-hour continuous infusion and as a bolus injection of equal dose in patients with nephrotic syndrome,and to investigate a preferable administration mode of torasemide for these patients.Methods Twenty-three hospitalized patients were randomized to receive torasemide 20 mg or 40 mg per day by either 2-hour intravenous infusion or bolus injection,and interchanged after 48 hours of washout.Results Patients received torasemide by 2-hour intravenous infusion exhibited significantly higher daily urinary volume,chloride excretion,sodium excretion and fractional excretion of sodium (FENa) within 24 hours than those by bolus injection (P ＜ 0.05).Significantly lower bound-state torasemide excretion,higher ratio of urinary volume to torasemide excretion and a markedly larger area under the curve in the plasma concentrationtime profiles were also observed in the infusion group (P ＜ 0.05).Conclusion 2-hour continuous infusion delivers a better diuretic effect compared with a bolus injection of equal dose of torasemide in patients with nephrotic syndrome.