乙酰唑胺对表达水孔蛋白1的非洲爪蟾卵母细胞转运水功能的影响

目的观察乙酰唑胺对水孔蛋白1(AQP1)水转运功能的影响。方法将AQP1 cRNA 10 ng注射入非洲爪蟾卵母细胞,观察并记录给予1×10^-7～1×10^-5 mol·L^-1乙酰唑胺后卵母细胞在低渗溶液中的膨胀率,并计算其渗透水通透性(Pf)的变化。结果非洲爪蟾卵母细胞表达AQP1蛋白后,在低渗溶液中迅速膨胀,Pf值显著增加至1.82×10^-2 cm·s^-1,而注射水的阴性对照仅为0.25×10^-2 cm·s^-1。AQP抑制剂HgCl₂使Pf值降至0.64×10^-2 cm·s^-1;1×10^-7～1×10^-5 mol·L^-1乙酰唑胺处理后,Pf值分别降至1.43,1.24和0.93×10^-2 cm·s^-1。结论乙酰唑胺剂量依赖性地降低AQP1介导的渗透水通透性,抑制AQP1转运水的功能。     

汞化合物对大鼠游离肾近曲小管细胞毒性及其指标的探讨

本文观察了氯化汞和氯化甲基汞对游离大鼠肾近曲小管的毒性作用,并比较了各毒性指标的敏感性。结果表明,肾近曲小管细胞内乳酸脱氢酶(LDH)和 β-葡糖苷酸酶(GCR)漏出、GSH 和蛋白质巯基(PSH)含量的降低均与汞化合物浓度及温育时间成良好的剂量-效应和时间-效应关系;而天冬氨酸氨基转移酶(AST)和酸性磷酸酶(AcP)漏出的剂量-效应关系不明显。各观察指标的敏感性依次为 GSH>PSH≥LDH≥GCR>AST>AcP。两种汞化合物对肾小管脂质过氧化作用不明显。     

XJ-6-A抑制肿瘤生长转移作用与水孔蛋白1的关系

研究目的XJ-6-A是我室与北京大学化学院合作，根据水通道蛋白1（Aquaporin1，AQP1）的空间结构和碳酸酐酶抑制剂（Carbonic Anhydrase Inhibitor，CAI）的化学结构，借助于计算机辅助药物设计合成的具有抑制肿瘤转移潜在活性的AQP1抑制剂。XJ-6-A在20mg／kg时具有明显的抑制肿瘤生长及转移作用。XJ-6-A在剂量为0．1μM和1μM时，能明显抑制细胞水转运功能。本研究旨在进一步证实XJ-6-A抑制肿瘤生长转移作用，探讨其可能的作用机制，以期发现具有抑制肿瘤生长转移作用的AQP1抑制剂。     

黄芩苷对STZ糖尿病大鼠肾脏的保护及其与TGF-β1的关系

目的:探讨黄苷甙对糖尿病大鼠肾脏病变的影响。方法:将实验大鼠随机分为3组:正常对照组(C)、STZ糖尿病对照组(DC)和糖尿病黄芩苷灌胃组(DB),所用黄芩苷剂量为200mg.kg-1。实验为期4周,观察血糖、糖化血红蛋白、肾质量/体质量比和尿白蛋白排泄率(UAER),用免疫组化法检测肾小球转化生长因子β1(TGF-β1)的表达。结果:(1)糖尿病大鼠血糖和糖化血红蛋白增高、肾质量/体质量比增加,肾小球节段性系膜细胞增生,肾小管空泡变性,少数肾小管上皮细胞坏死,肾小球TGF-β1表达增加;(2)DB组和DC组相比血糖和肾质量/体质量比无明显变化,但糖化血红蛋白明显降低,尿白蛋白排泄率降低,肾小球无明显异常,肾小管上皮轻度空泡变性,TGF-β1表达减少。结论:黄芩苷对STZ糖尿病大鼠肾脏病变具有一定的保护作用,其机制可能与抑制蛋白糖化及TGF-β1表达减少有关。     

白藜芦醇抑制人结肠癌细胞增殖的作用与促进骨形态蛋白9及其受体表达的关系研究

目的研究白藜芦醇(resveratrol,Res)对人结肠癌LoVo细胞增殖的抑制作用与骨形态蛋白9(bone morphorgenetic protein 9,BMP9)之间的可能关系。方法采用结晶紫染色与流式细胞术检测Res对Lo Vo细胞增殖的抑制作用;流式细胞术检测Res对Lo Vo细胞凋亡的诱导作用。利用RTPCR和Western blot检测Res在Lo Vo细胞中对BMP9表达的影响,以及对BMP9的受体ALK2和ALK3表达的影响。采用ALK2和ALK3的抑制剂,通过结晶紫染色分析BMP9介导Res抑制Lo Vo细胞增殖的可能机制。结果与对照组相比,Res明显呈浓度依赖性抑制Lo Vo细胞增殖,并诱导Lo Vo细胞发生S期阻滞;Res呈浓度依赖性增加Lo Vo细胞凋亡比例;Res促进BMP9的mRNA表达并明显增加其蛋白水平;外源性过表达BMP9能增强Res对Lo Vo细胞的增殖抑制和诱导凋亡作用;Res能诱导BMP9的受体ALK2和ALK3的mRNA表达,抑制ALK2和ALK3能明显促进Lo Vo细胞增殖,并减弱Res对Lo Vo细胞增殖的抑制作用。结论Res对Lo Vo细胞的增殖具有明显抑制作用,这种作用可能与Res促进BMP9及其受体表达有关。     

海昆肾喜对糖尿病肾病大鼠肾脏保护作用及其对肾组织TGF-β1蛋白及mRNA表达的影响

目的 探讨海昆肾喜对糖尿病肾病大鼠肾组织转化生长因子-β1(TGF-β1)蛋白及mRNA表达的影响.方法 50只大鼠空腹一次性腹腔注射链脲佐茵素造成糖尿病模型,并按血糖高低随机分为2组、试验组灌胃海昆肾喜,给药12周.第4、8、12周末收集大鼠24h尿量及检测尿蛋白量.12周末处死大鼠,取血并分离血清检测肌酐(Scr)、尿素氮(BUN)和甘油三酯(TG)等,取肾后固定包埋切片,采用HE、Mallory染色观察肾组织病理改变,并应用免疫组化检测肾组织TGF-β1及用原位杂交检测肾组织TGF-β1mRNA的表达.结果 海昆肾喜能够降低糖尿病大鼠的蛋白尿,增加体重.降低血清Scr和BUN,改善肾功能,调节TG,改善脂代谢紊乱,并且能够降低糖尿病大鼠肾小管上皮细胞、肾间质细胞浆TGF-β1及mRNA的表达.结论 海昆肾喜可能抑制TGF-β1蛋白及mRNA的过度表达,进而减缓糖尿病肾病的病程进展.     

当归芍药散活性部位JD-30对淀粉样β蛋白片段25-35抑制大鼠海马脑片CA1区长时程增强的改善作用

目的研究当归芍药散改善学习记忆能力的物质基础和作用机理。方法采用细胞外微电极记录技术,记录大鼠海马脑片CA1区群峰电位(PS)幅值和高频刺激诱发LTP后PS的增幅。结果用含当归芍药散活性部位JD-30(25,50和100mg.L-1)的人工脑脊液灌流大鼠海马脑片,其CA1区的PS幅值无明显变化。用相同浓度的JD-30孵育海马脑片90min以上并持续灌流,其CA1区高频刺激后的PS增幅与空白对照组相比无明显差异。而用Aβ25-35200nmo.lL-1处理的海马脑片CA1区高频刺激后的PS增幅受到明显抑制;若同时给予Aβ25-35和上述浓度的JD-30处理海马脑片,CA1区高频刺激后的PS增幅较Aβ25-35组升高,其中JD-30100mg.L-1组的PS增幅达到正常对照组水平。提示JD-30对正常海马脑片CA1区的基础突触传递和LTP没有影响,但可改善Aβ25-35所抑制的LTP。结论JD-30可改善神经突触可塑性,拮抗Aβ对LTP的抑制作用可能是其益智机制之一。     

针刺激活轴抑制蛋白1、腺苷酸活化蛋白激酶、丝/苏氨酸蛋白激酶信号通路对失神经骨骼肌萎缩大鼠的保护作用

目的研究针刺对失神经骨骼肌萎缩大鼠骨骼肌细胞丝/苏氨酸蛋白激酶(AKT)、腺苷酸活化蛋白激酶(AMPK)、轴抑制蛋白1(Axin1)表达水平的影响。方法将48只SD大鼠采用简单随机分组分为空白对照组、假手术组、模型组和针刺组各12只。模型组和针刺组大鼠采用手术切断坐骨神经制备失神经骨骼肌萎缩大鼠模型,假手术组只暴露坐骨神经,空白对照组不做任何处理。针刺组在造模后进行电针治疗(“足三里”和“承山”穴),每次10 min,连续治疗3周。治疗后,检测各组大鼠绯肠肌组织的湿重比、肌纤维横截面积及肌细胞直径比;HE染色检测各组大鼠绯肠肌损伤;TUNEL染色检测各组大鼠绯肠肌细胞凋亡;蛋白质印迹法(Western blotting)检测p-AKT、AKT、p-AMPK、AMPK、Axin1、B 细胞淋巴瘤2(Bcl-2)、Bcl 相关X 蛋白(Bax)、活化胱天蛋白酶(cleaved caspase-3)和增殖细胞核抗原(PCNA)蛋白的表达。结果与空白对照组和假手术组相比,模型组大鼠腓肠肌湿重比(0.38±0.06)、肌纤维截面积比(0.52±0.12)和肌纤维直径比(0.53±0.16)均明显下降(P<0.05),细胞凋亡率(30.85±5.74)%明显升高(P<0.05),Bcl-2(0.40±0.03)、Bax(0.53±0.05)、cleaved caspase-3(0.58±0.06)、PCNA(0.44±0.05)、p-AKT/AKT(0.54±0.06)、p-AMPK/AMPK(0.73±0.04)和Axin1(0.41±0.05)的表达明显上调(P<0.05);与模型组相比,针刺组大鼠腓肠肌湿重比(0.52±0.07)、肌纤维截面积比(0.64±0.11)和肌纤维直径比(0.66±0.15)均明显增加(P<0.05),细胞凋亡率(21.39±3.87)%明显下降(P<0.05),Bcl-2(0.61±0.05)、PCNA(0.72±0.08)、p-AKT/AKT(0.82±0.09)和Axin1(0.62±0.06)的表达明显上调(P<0.05),Bax(0.33±0.04)、cleaved caspase-3(0.34±0.04)和p-AMPK/AMPK(0.51±0.03)的表达明显下调(P<0.05)。结论针刺可能通过调控Axin1/AMPK/AKT的表达,延缓失神经大鼠骨骼肌的萎缩。     

多毛孢菌菌粉抑制庆大霉素诱导的猪肾小管上皮细胞凋亡及纤维化生长因子的表达

目的：研究人工培养的多毛孢菌菌粉水提物对庆大霉素诱导的近端肾小管上皮细胞损伤、凋亡的保护作用及对碱性纤维化生长因子(basic fibro-blast growth factor，bFGF)mRNA表达的影响。方法：将猪近端肾小管上皮细胞株(LLCPK)复苏培养，分成正常对照组、庆大霉素组和多毛孢菌组，除对照组外，用庆大霉素刺激，多毛孢菌组同时加多毛孢菌菌粉水提物干预。以MTT法观测存活细胞数；并测定细胞上清液N-乙酰-β-D-氨基糖苷酶(NAG)浓度；荧光标记细胞表面Annexin V，以细胞流式法测定其表达；RT-PCR检测细胞碱性纤维化生长因子mRNA的表达。结果与结论：庆大霉素可引起细胞存活率的显降低，N-乙酰-β-D-氨基糖苷酶浓度显增高；并提高细胞Annexin V的表达，即诱导白细胞调亡，和诱导LLCPK细胞bFGF mRNA的表达。多毛孢菌菌粉水提物能提高肾小管上皮细胞LLCPK存活率，降低细胞调亡数，并显抑制bFGF mRNA的表达。     

Lack of formic acid production in rat hepatocytes and human renal proximal tubule cells exposed to chloral hydrate or trichloroacetic acid

The industrial solvent trichloroethylene (TCE) and its major metabolites have been shown to cause formic aciduria in male rats. We have examined whether chloral hydrate (CH) and trichloroacetic acid (TCA), known metabolites of TCE, produce an increase in formic acid in vitro in cultures of rat hepatocytes or human renal proximal tubule cells (HRPTC). The metabolism and cytotoxicity of CH was also examined to establish that the cells were metabolically active and not compromised by toxicity. Rat hepatocytes and HRPTC were cultured in serum-free medium and then treated with 0.3–3 mM CH for 3 days or 0.03–3 mM CH for 10 days, respectively and formic acid production, metabolism to trichloroethanol (TCE-OH) and TCA and cytotoxicity determined. No increase in formic acid production in rat hepatocytes or HRPTC exposed to CH was observed over and above that due to chemical degradation, neither was formic acid production observed in rat hepatocytes exposed to TCA. HRPTC metabolized CH to TCE-OH and TCA with a 12-fold greater capacity to form TCE-OH versus TCA. Rat hepatocytes exhibited a 1.6-fold and three-fold greater capacity than HRPTC to form TCE-OH and TCA, respectively. CH and TCA were not cytotoxic to rat hepatocytes at concentrations up to 3 mM/day for 3 days. With HRPTC, one sample showed no cytotoxicity to CH at concentrations up to 3 mM/day for 10 days, while in another cytotoxicity was seen at 1 mM/day for 3 days. In summary, increased formic acid production was not observed in rat hepatocytes or HRPTC exposed to TCE metabolites, suggesting that the in vivo response cannot be modelled in vitro. CH was toxic to HRPTC at millimolar concentrations/day over 10 days, while glutathione derived metabolites of TCE were toxic at micromolar concentrations/day over 10 days [Lock, E.A., Reed, C.J., 2006. Trichloroethylene: mechanisms of renal toxicity and renal cancer and relevance to risk assessment. Toxicol. Sci. 19, 313–331] supporting the view that glutathione derived metabolites are likely to be responsible for nephrotoxicity.     

Inducible nitric oxide synthase and apoptosis in murine proximal tubule epithelial cells.

Since inducible nitric oxide synthase (iNOS) and proximal tubule injury are known to be critical determinants of lipopolysaccharide (LPS)-induced renal failure, the role of nitric oxide (NO) in proximal tubule cell apoptosis was examined. An 18-h treatment with a combination of LPS (5 microg/ml) and interferon-gamma (IFN-gamma, 100 units/ml) synergistically induced iNOS and produced a 20-fold increase in NO generation in the TKPTS murine proximal tubule cell line. NO generation by LPS + IFN-gamma was blocked by a specific iNOS blocker, L-N6-(1-iminoethyl)-lysine (L-NIL, 1 mM). To assess the role of iNOS-derived NO in proximal tubule cell apoptosis, annexin V- and propidium iodide-labeled cells were analyzed by flow cytometry. Neither the induction of iNOS nor its inhibition produced significant apoptotic cell death in TKPTS cells. Two exogenous NO donors were used to examine the role of NO more directly in proximal tubule apoptosis. Although both sodium nitroprusside (SNP), an iron-containing, nitrosonium cation donor, and S-nitroso-N-acetylpenicillamine (SNAP), a noniron-containing, NO generator, produced a concentration-dependent increase in NO generation, only SNP increased apoptotic cell death in TKPTS cells (5.9 +/- 0.7% in control cells vs. 21.6 +/- 3.8% in SNP [500 microM]-treated cells; n = 4-9; p < 0.01). SNP-mediated tubule cell apoptosis was not dependent on the activation of caspases or p53 but was possibly related to the generation of reactive oxygen species by SNP. Thus, in TKPTS cells induction of iNOS and generation of NO by LPS does not lead to tubular epithelial cell death.     

Role of Arf1 in endosomal trafficking of protein-metal complexes and cadmium-metallothionein-1 toxicity in kidney proximal tubule cells

Cadmium (Cd) is nephrotoxic. Circulating Cd-metallothionein complexes (CdMT) are filtered by the kidney, reabsorbed by proximal tubule cells (PTC) via receptor-mediated endocytosis, and trafficked to lysosomes which results in apoptosis. ADP-ribosylation factors (Arfs) regulate vesicular trafficking. Arf1 is traditionally associated with the secretory pathway, but has been recently found involved in endocytotic trafficking in PTC. Hence, the role of Arf1 was investigated in MT-1 and transferrin (Tf) endocytosis, and in CdMT-1-induced cell death in a PTC line by overexpressing Arf1-wildtype (WT) or dominant-negative mutant Arf1-T31N. Endogenous Arf1 distribution in PTC was punctate throughout the cytosol, but was not detected in the plasma membrane. Arf1 colocalized with markers for sorting to late endosomes (Rab7, CLC6). Arf1 weakly overlapped with the late endosomal/lysosomal marker CLC7, but not with markers for early (Rab5, CLC5) and recycling endosomes (Rab11). Arf1-T31N significantly attenuated CdMT-1 toxicity by ∼60% when compared to Arf1-WT. However, overexpression of Arf1-T31N did not prevent internalization of Alexa Fluor 546-coupled Tf or MT-1 which accumulated in an EEA1-positive early endocytotic compartment, but not in Arf1-WT overexpressing cells. We conclude that Arf1 is involved in trafficking of protein-metal complexes, including CdMT, to late endosomes/lysosomes in renal PTC.     

Mechanisms of the ifosfamide-induced inhibition of endocytosis in the rat proximal kidney tubule

The Fanconi syndrome is a common side effect of the chemotherapeutic agent ifosfamide. Current evidences suggest that chloroacetaldehyde (CAA), one of the main metabolites of ifosfamide activation, contributes to its nephrotoxicity. However, the pathophysiology of CAA-induced Fanconi syndrome is not fully understood. The present work examined the adverse effects of CAA on precision-cut rat renal cortical slices, which allowed studying the toxic effect of CAA on proximal endocytosis. We demonstrated that clinically relevant concentrations of CAA (/=75 muM has adverse effects, both on viability parameters and on energy metabolism, as shown by the great decrease in total glutathione and ATP levels. In addition, the V-ATPase, which plays a crucial role in intracellular vesicle trafficking, was inhibited by 100 muM of CAA. By contrast, the slight decrease in Na-K-ATPase activity observed for CAA>/= 125 muM (maximum inhibition: 33%) could not totally explain the inhibition of the reabsorption processes. In conclusion, the addition of the two main adverse effects of CAA (decrease in ATP levels and inhibition of the V-ATPase) could explain the inhibition of endocytosis and the Fanconi syndrome observed during ifosfamide treatments.     

The effect of big endothelin-1 in the proximal tubule of the rat kidney

1. An obligatory step in the biosynthesis of endothelin-1 (ET-1) is the conversion of its inactive precursor, big ET-1, into the mature form by the action of specific, phosphoramidon-sensitive, endothelin converting enzyme(s) (ECE). Disparate effects of big ET-1 and ET-1 on renal tubule function suggest that big ET-1 might directly influence renal tubule function. Therefore, the role of the enzymatic conversion of big ET-1 into ET-1 in eliciting the functional response (generation of 1,2-diacylglycerol) to big ET-1 was studied in the rat proximal tubules.
2. In renal cortical slices incubated with big ET-1, pretreatment with phosphoramidon (an ECE inhibitor) reduced tissue immunoreactive ET-1 to a level similar to that of cortical tissue not exposed to big ET-1. This confirms the presence and effectiveness of ECE inhibition by phosphoramidon.
3. In freshly isolated proximal tubule cells, big ET-1 stimulated the generation of 1,2-diacylglycerol (DAG) in a time- and dose-dependent manner. Neither phosphoramidon nor chymostatin, a chymase inhibitor, influenced the generation of DAG evoked by big ET-1.
4. Big ET-1-dependent synthesis of DAG was found in the brush-border membrane. It was unaffected by BQ123, an ET_A receptor antagonist, but was blocked by bosentan, an ET_A,B-nonselective endothelin receptor antagonist.
5. These results suggest that the proximal tubule is a site for the direct effect of big ET-1 in the rat kidney. The effect of big ET-1 is confined to the brush-border membrane of the proximal tubule, which may be the site of big ET-1-sensitive receptors.

     

Stx2 Induces Differential Gene Expression and Disturbs Circadian Rhythm Genes in the Proximal Tubule

Shiga toxin-producing Escherichia coli (STEC) causes proximal tubular defects in the kidney. However, factors altered by Shiga toxin (Stx) within the proximal tubules are yet to be shown. We determined Stx receptor Gb3 in murine and human kidneys and confirmed the receptor expression in the proximal tubules. Stx2-injected mouse kidney tissues and Stx2-treated human primary renal proximal tubular epithelial cell (RPTEC) were collected and microarray analysis was performed. We compared murine kidney and RPTEC arrays and selected common 58 genes that are differentially expressed vs. control (0 h, no toxin-treated). We found that the most highly expressed gene was GDF15, which may be involved in Stx2-induced weight loss. Genes associated with previously reported Stx2 activities such as src kinase Yes phosphorylation pathway activation, unfolded protein response (UPR) and ribotoxic stress response (RSR) showed differential expressions. Moreover, circadian clock genes were differentially expressed, suggesting Stx2-induced renal circadian rhythm disturbance. Circadian rhythm-regulated proximal tubular Na⁺-glucose transporter SGLT1 (SLC5A1) was down-regulated, indicating proximal tubular functional deterioration, and mice developed glucosuria confirming proximal tubular dysfunction. Stx2 alters gene expression in murine and human proximal tubules through known activities and newly investigated circadian rhythm disturbance, which may result in proximal tubular dysfunctions.     

Effects of lead intoxication on intercellular junctions and biochemical alterations of the renal proximal tubule cells

Lead intoxication is a worldwide health problem which frequently affects the kidney. In this work, we studied the effects of chronic lead intoxication (500 ppm of Pb in drinking water during seven months) on the structure, function and biochemical properties of rat proximal tubule cells. Lead-exposed animals showed increased lead concentration in kidney, reduction of calcium and amino acids uptake, oxidative damage and glucosuria, proteinuria, hematuria and reduced urinary pH. These biochemical and physiological alterations were related to striking morphological modifications in the structure of tubule epithelial cells and in the morphology of their mitochondria, nuclei, lysosomes, basal and apical membranes. Interestingly, in addition to the nuclei, inclusion bodies were found in the cytoplasm and in mitochondria. The epithelial cell structure modifications included an early loss of the apical microvillae, followed by a decrement of the luminal space and the respective apposition and proximity of apical membranes, resulting in the formation of atypical intercellular contacts and adhesion structures. Similar but less marked alterations were observed in subacute lead intoxication as well. Our work contributes in the understanding of the physiopathology of lead intoxication on the structure of renal tubular epithelial cell–cell contacts in vivo.     

酸性成纤维细胞生长因子对庆大霉素诱导的肾小管上皮细胞损伤的保护作用

目的研究酸性成纤维细胞生长因子(aFGF)对庆大霉素引起的体外培养的大鼠肾小管上皮细胞损害的保护作用。方法大鼠肾皮质经研磨、过网、胰蛋白酶消化,进行肾小管上皮细胞的体外培养。用庆大霉素建立损伤模型,观察aFGF对损伤的肾小管上皮细胞的保护作用。结果①经形态学观察、GM组与对照组比较,CAT、SOD、Na~+,K~+-ATP酶活性下降,而NAG活性和MDA升高(P<0.01),提示肾小管上皮细胞的培养和庆大霉素损伤的建模成功。②aFGF+GM组与GM组比较,各生化和酶学指标差异均有显著性(P<0.01);而aFGF+GM组与对照组比较,CAT、NAG、Na~+,K~+-ATP酶活性差异无显著性,但SOD活性下降、MDA升高差异仍有显著性(P<0.05)。结论aFGF对庆大霉素诱导的肾小管上皮细胞损伤有明显的保护作用。