Role of leucocyte adhesion molecules in aminonucleoside of puromycin (PAN)-associated interstitial nephritis

Rats receiving a single dose (10 mg/100 g body wt) of PAN develop severe proteinuria and acute interstitial nephritis. To investigate the mechanisms involved in interstitial leucocyte accumulation, we examined the expression of adhesion molecules on kidney tissue sections as well as on endothelial cell cultures. We also performed in vivo treatments with antibodies against adhesion molecules. Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) was found on day 7 of the disease, when interstitial nephritis was first detected. Also, rat endothelial cells in culture showed maximal expression of ICAM-1 in the presence of 10⁻⁹–10⁻¹¹m PAN. Adhesion of peripheral blood mononuclear cells (PBMC) on kidney sections from PAN-treated rats was highest on day 7 (3.05±0.7 (mean±s.e.m.); controls 0.75±0.5). Such increased adhesion was notably blocked after PAN-treated rat kidney sections were incubated with anti-ICAM-1 MoAb (0.9±0.4). In addition, adhesiveness of PBMC to PAN-stimulated endothelial cells in culture was enhanced (25±2.5%; non-stimulated cells 13±3.1%). The addition of specific MoAbs against ICAM-1 and lymphocyte function-associated antigen-1 (LFA-1) produced a high blockage of adhesiveness induced by exposure to PAN (inhibition 58±3%; non-stimulated cells 40±7%). Simultaneous administration to PAN-treated rats of anti-LFA-1 and anti-ICAM-1 MoAbs reduced the number of interstitial cells by 70% compared with the 30% of reduction obtained when anti-very late antigen-4 (VLA-4) MoAb and anti-vascular cell adhesion molecule-1 (VCAM-1) antibodies were used. Our results suggest that the LFA-1/ICAM-1 pathway plays a principal role in the interstitial nephritis occurring in rats with PAN-nephrosis.     

越婢汤和固精方对嘌呤霉素氨基核苷肾病大鼠肾小球足细胞损伤的影响

目的探讨发汗解表法(越婢汤)与补肾固精法(固精方)治疗肾病综合征的疗效及可能机制。方法 40只Wistar大鼠随机分为正常组、模型组、越婢汤组、固精方组,每组10只。除正常组外其余各组大鼠采用单次尾静脉注射嘌呤霉素氨基核苷9 mg/100 g建立肾小球足细胞损伤大鼠模型。造模后第2天开始越婢汤组每天灌胃给予含生药越婢汤2.1 g/100 g,固精方组每天给予含生药固精方7.5 g/100 g,正常组及模型组灌胃等体积蒸馏水,连续2周。检测各组大鼠血清肌酐、尿素氮、尿酸、白蛋白、总胆固醇、甘油三酯,尿蛋白定量和尿肌酐,肾组织TRPC5、TRPC6蛋白及mRNA表达,观察肾小球病理改变及足细胞超微结构。结果与正常组比较,模型组大鼠尿素氮、尿酸、总胆固醇、甘油三酯上升,血清白蛋白水平降低,尿蛋白肌酐比增加,肾组织TRPC5、TRPC6蛋白及mRNA表达均升高(P<0.05)。与模型组比较,越婢汤及固精方组血清尿素氮、尿酸、总胆固醇、甘油三酯、尿蛋白肌酐比下降,白蛋白上升,肾组织TRPC5、TRPC6 mRNA亦降低(P<0.05)。越婢汤组血清白蛋白、尿酸水平、肾组织TRPC5 mRNA表达低于固精方组,而TRPC6 mRNA高于固精方组(P<0.05)。结论越婢汤、固精方可能通过调控肾组织TRPC5及TRPC6表达,减轻足细胞损伤,从而改善肾病综合征的低蛋白、高血脂表现。     

Effect of down-regulation of TRPC6 on the puromycin aminonucleoside-induced apoptosis of mouse podocytes

Eukaryotic expression vectors carrying the small hairpin RNA （shRNA） for TRPC6 mRNA were constructed, and the effects of knocking-down TRPC6 on puromycin aminonucleoside （PAN）-induced apoptosis of mouse podocytes were observed. Two eukaryotic expression vectors containing small hairpin structure targeting TRPC6 named pGCsi-TRPC6A and pGCsi-TRPC6B were designed and synthesized. The plasmids were transfected into conditionally immortalized murine podocyte cell line by liposome. The changes in the TRPC6 mRNA and protein expression were observed by RT-PCR and Western blot after 48 h. Cultured podocytes were divided into four groups： control group, PAN treatment group, PAN treatment＋shRNA transfection group, and PAN treatment＋negative control group. The expression of Bax and Bcl-2 mRNA and proteins was detected by RT-PCR and Western-blot respectively. The apoptotic rate of podocytes was measured by flow cytometry. The results showed that the expression of TRPC6 mRNA and protein was decreased in the podocytes when transfected with pGCsi-TRPC6A, and pGCsi-TRPC6B. The expression of Bax was increased, and that of Bcl-2 was decreased at protein and mRNA levels in the podocytes after treated with PAN for 48 h. These changes was attenuated by knocking-down TRPC6. Knocking-down TRPC6 could effectively decrease the PAN-induced apoptosis of podocytes. It was concluded that TRPC6 may play an important role in the PAN-induced apoptosis of podocytes. Knocking-down TRPC6 gene could effectively prevent the podocytes from apoptosis induced by PAN.     

应用CRISPR/Cas9技术构建MAVS基因敲除的ZR-751乳腺癌细胞株

目的 运用成簇的规律间隔短回文重复序列(CRISPR)/Cas9基因编辑技术,构建线粒体抗病毒信号蛋白(MAVS)基因敲除的ZR-751乳腺癌细胞株,研究MAVS对细胞生长的影响.方法 针对MAVS基因第一外显子设计小向导RNA(sgRNA),构建pX459-sgRNA重组质粒.然后利用嘌呤霉素筛选ZR-751 MAVS基因敲除的阳性克隆,Western印迹检测MAVS基因敲除情况,提取克隆基因组进行测序鉴定.平板克隆实验检测MAVS被敲除后对细胞增殖的影响,再利用MTS实验检测在DFX培养基刺激下,MAVS对细胞死亡的影响.结果 Western印迹结果说明ZR-751细胞株内MAVS已完全敲除;且在凋亡诱导剂DFX刺激下,MAVS被敲除后促进细胞增殖.结论 利用CRISPR/Cas9系统成功构建了MAVS基因敲除的ZR-751乳腺癌细胞株,初步实验提示MAVS抑制乳腺癌细胞生长,为后续研究MAVS在肿瘤中的功能奠定了基础.     

足细胞特异性因子nephrin及肿瘤蛋白-1在肾小球硬化过程中表达变化

目的：应用嘌罗霉素氨基核苷（PAN）模型，通过观察临床、病理指标及足细胞特异性因子nephrin和肿瘤蛋白-1（WT-1）在足细胞的表达，了解足细胞损害在肾小球硬化过程中的重要作用。方法尾静脉注射PAN制作大鼠肾病模型，测定不同时间点的生化指标，处死大鼠，取其肾脏，石蜡包埋切片，PAS及免疫组化染色，测定肾小球硬化指数（GSI），肾小球面积（GA），nephrin及WT-1的表达，进行统计学分析。结果 PAN组在早期（第8天）表现为典型肾病综合征，后期（20周）表现为慢性肾炎。形态学方面，PAN组的GSI在4，14，20周均明显高于对照组（P＜0.05）。PAN组GA在14周时大于对照组（P＜0.01），但在20周时小于对照组（P＜0.001），并且20周时GSI与GA之间呈强负相关关系。PAN组nephrin表达在4，14，20周时与对照组比较均有所减少（P＜0.05），与此同时，WT-1的表达在14和20周时较对照组明显减少（P＜0.001）。结论（1）在肾炎发展中，随着时间延长，GSI增高，GA缩小，并且GSI和GA之间呈负相关。（2）在肾小球硬化发展中， nephrin和WT-1的表达进行性减少，说明有明显足细胞数量的减少。因此，足细胞的损伤与肾小球硬化密切相关。     

锰苯甲酸卟啉在嘌呤霉素氨基核苷诱导的大鼠肾脏病模型中的作用

目的:探讨超氧化物歧化酶类似物锰苯甲酸卟啉(MnTBAP)在嘌呤霉素氨基核苷(puromycin aminonucleoside,PAN)诱导的大鼠肾脏病模型中的作用?方法:24只雄性SD大鼠按照每组8只随机分为正常对照组?模型组(一次性尾静脉注射150 mg/kg PAN建立PAN诱导的大鼠肾脏病模型)?MnTBAP治疗组[造模大鼠于造模当天开始腹腔注射MnTBAP 10 mg/(kg·d),共给药14 d]?收集大鼠24 h尿液,Bradford法检测24 h尿蛋白总量;应用透射电镜观察肾小球足细胞的超微结构;实时荧光定量PCR法在mRNA水平检测足细胞裂孔隔膜蛋白Nephrin和Podocin的表达量;Western blot在蛋白质水平检测Nephrin和Podocin的表达量?结果:①与正常对照组相比,模型组大鼠的24 h尿蛋白总量明显升高(P < 0.01),肾脏指数升高(P < 0.01);MnTBAP治疗后大鼠24 h尿蛋白总量较模型组下降(P < 0.01),肾脏指数较模型组下降(P < 0.01);②透射电镜观察结果表明,模型组大鼠的肾小球足细胞足突出现广泛融合甚至消失,MnTBAP治疗后这种现象得以改善;③实时荧光定量PCR结果显示,模型组大鼠肾皮质Nephrin和Podocin的mRNA表达较正常对照组降低(P < 0.01),MnTBAP治疗组Nephrin和Podocin的mRNA表达较模型组增加(P < 0.01);④Western blot结果显示,模型组大鼠肾皮质Nephrin和Podocin蛋白的表达较正常对照组降低(P < 0.01),MnTBAP治疗组Nephrin和Podocin蛋白的表达较模型组增加(P < 0.01)?结论:MnTBAP可以降低PAN诱导的肾病大鼠的蛋白尿,并明显减轻足细胞损伤?     

SRT1720对实验性肾病大鼠足细胞的保护作用

目的:探讨沉默信息调节因子2相关酶1(silent mating type information regulation 2 homolog 1,SIRT1)激活剂SRT1720对嘌呤霉素氨基核苷肾病(puromycin aminonucleoside nephrosis,PAN)大鼠足细胞损伤的保护作用?方法:雄性SD大鼠一次性腹腔注射150 mg/kg嘌呤霉素氨基核苷建立PAN肾病大鼠模型,设正常对照组?模型组?SRT1720治疗组[模型组大鼠给予SRT1720 100 mg/(kg?d)灌胃]?Bradford法检测大鼠的24 h尿蛋白总量;应用透射电镜观察足细胞超微结构;实时定量RT-PCR?Western blot 检测足细胞裂孔隔膜蛋白Nephrin及Podocin的表达?结果:①与正常对照组相比,PAN注射后第3天,模型组大鼠尿蛋白的排泄量开始增加(P < 0.01),至第7天达最高峰,尿蛋白总量达259.73 mg/24 h;SRT1720治疗组在治疗3 d后尿蛋白明显降低(P < 0.01),第7天则降到52.47 mg/24 h;②模型组大鼠血清白蛋白显著降低[(22.14 ± 3.05)g/L]而胆固醇则显著升高[(7.03 ± 1.64)mmol/L],SRT1720治疗后显著提高模型组大鼠血清白蛋白水平[(35.48 ± 3.96)g/L]并降低胆固醇水平[(2.81 ± 0.41)mmol/L];③透射电镜结果显示模型组大鼠肾小球足细胞足突广泛融合?消失,SRT1720治疗显著减轻足细胞足突的融合;④与正常对照组相比,模型组大鼠肾组织中Nephrin和Podocin核酸和蛋白表达均显著降低,SRT1720治疗组肾组织中Nephrin和Podocin表达显著上调,能够恢复到正常组的85%~90%?结论:SRT1720能够降低PAN大鼠蛋白尿,改善低蛋白血症和高胆固醇血症,并明显减轻足细胞损伤?     

Cloning and expression of the mouse glomerular podoplanin homologue gp38P.

BACKGROUND: Puromycin aminonucleoside nephrosis (PAN) is a rat model for human minimal change nephropathy. During PAN, severe proteinuria is induced that is paralleled by a reduced expression of a rat podocyte protein, named podoplanin. The protein probably plays a role in maintaining the unique shape of podocytes. Recently, attenuated amino acid transport has been observed in cultured mouse glomerular epithelial cells treated with puromycin aminonucleoside (PA). In the present study, gp38P, a protein homologous to rat podoplanin was cloned from mouse glomerular epithelial cells and was found to be down-regulated by PA. A role for gp38P in membrane transport in mouse podocytes has been suggested. METHODS: Based on homology to rat podoplanin, the protein gp38P was cloned from mouse glomerular epithelial cells by RT-PCR. Mouse glomerular epithelial cells, mouse cortical collecting duct cells, and Xenopus oocytes were treated with PA and the expression of gp38P was examined by RT-PCR and western blot analysis. Expression of gp38P in other mouse tissues was demonstrated by RT-PCR. The possible impact of gp38P on amino acid transport and folic acid uptake was examined in Xenopus oocytes. RESULTS: gp38P cloned from mouse glomerular epithelial cells showed strong homologies to rat podoplanin and gp38, a protein expressed in the thymus and other tissues. RT-PCR analysis demonstrated ubiquitous expression of gp38P in epithelial and non-epithelial tissues. Quantitative RT-PCR and western blot analysis indicated down-regulation of gp38P in PA-treated glomerular epithelial cells along with loss of cell shape and cell lysis, which was not observed in other cell types. When expressed in Xenopus oocytes, gp38P had no impact on folic acid uptake or transport activity of the amino acid co-transporters CAT1, EAAC1, and rBAT. CONCLUSION: Cultured mouse glomerular epithelial cells express the podoplanin homologue gp38P, which is down-regulated by PAs. gp38P is ubiquitously expressed and is likely to control specifically the unique shape of podocytes.     

IQGAP1在调节足细胞细胞骨架重组中的作用

目的：探讨IQ 结 构 域 GTP 酶 活 化 蛋 白 1（IQ domain GTPase-activating protein 1, IQGAP1）对足细胞细胞骨架重组的调节作用。方法：嘌呤霉素（PAN）刺激小鼠足细胞后,运用实时定量PCR和Western blot印迹法分别检测细胞内IQGAP1 mRNA和蛋白表达水平,激光共聚焦显微镜观察足细胞骨架F-actin的分布,F-actin肌动蛋白评分系统（CFS）对骨架重组进行分析,并进一步观察上调和下调足细胞IQGAP1表达对PAN诱导的足细胞骨架重组的影响。结果：①与对照组相比,PAN刺激组足细胞内IQGAP1 mRNA和蛋白表达明显下降（P<0.05）,足细胞F-actin排列紊乱,CFS明显升高;②IQGAP1 siRNA进一步抑制IQGAP1表达后,PAN引起的上述足细胞F-actin重组更加明显（P<0.05）;③转染pCantag-myc-IQGAP1质粒促进IQGAP1表达后,PAN诱导的足细胞F-actin排列紊乱显著减轻,CFS明显下降（P<0.05）。结论：IQGAP1能抑制嘌呤霉素诱导的足细胞骨架重组,对维持足细胞正常骨架结构起着重要作用。     

ANTIPROTEINURIC EFFECT OF CALCIUM ANTAGONISTS ON PUROMYCIN-INDUCED EXPERIMENTAL NEPHROSIS

Calcium antagonists have a potential for beneficial effects on kidney function unrelated to their antihypertensive action. In this study we have investigated the efficacy of calcium antagonists compounds (verapamil, nifedipine and diltiazem) on reversible acute renal insufficiency, proteinuria and interstitial nephritis induced by the puromycin ammo nucleoside (PAN). An increase in blood pressure (BP) was detected on day 14, with no statistical differences in the response to calcium antagonists. Serum creatinine concentration increased to 1.2 mg/dL on day 7 after PAN and decreased to 0.7 mg/dL at 14 days, calcium antagonists shortened the time required to reach baseline or control levels. Calcium antagonists also reduced proteinuria in the PAN-treated animals, in both day 7 and day 14. Differential effects of the antagonists were observed. Verapamil caused a greater reduction (p < 0.01) in proteinuria than nifedipine or diltiazem in day 7. Moreover, verapamil (p < 0.01) and nifedipine (p < 0.01) reduced the total number of interstitial infiltrating leukocytes from 690 to 120 and 425 positive cells/20 high power fields (× 63) respectively, by contrast, diltiazem had no effect. We conclude that in this model of PAN nephropathy verapamil is more effective in reducing both proteinuria and the severity of acute interstitial nephritis than either nifedipine or diltiazem. The possible clinical implications of these results remain to be elucidated.