未分化和分化足细胞生物学性状及相关结构蛋白表达的变化

体外33℃许可条件下培乔由H-2Kb-tsA58转基因小鼠所建立的禾分化足细肥系,开在37℃非许可条件下诱导其分化.观察足细胞分化后形态学改变;MTT法测定细胞的生长曲线;红色荧光染料PKH-26标记足细胞,追踪其在子代细胞中的分布,检测细胞增殖能力;流式细胞仪检测细胞周期的改变;Western印迹检测足细胞相关蛋白CD2AP、α-actinin和足细胞分化相关蛋白nephrin的表达;免疫荧光结合激光共聚焦方法检测CD2AP、nephrin,α-actinin、F-肌动蛋白和微管蛋白的表达变化.结果显示:与未分化足细胞相比,分化足细胞形态发生改变,生长速度减慢,增殖能力下降:细胞周期表现为G0/G1期细胞比例的增多和S期及G2/M期的细胞比例下降;CD2AP、neDhrin和α-actinin的表达明显增高;CD2AP、nephrin、α-actinin、F-肌动蛋白和微管蛋白在表达分布上均发生明显的改变.以上结果表明,足细胞分化后生物学性状明显发生改变,细胞骨架重新分布:CD2AP、nephrin、α-actinin、F-肌动蛋白和微管蛋白均在足细胞的分化过程中发挥重要作用.     

应用siRNA技术探讨MCF-7乳腺癌细胞分泌的VEGF对树突状细胞的影响

为探讨MCF-7乳腺癌细胞分泌的血管内皮生长因子（ vascular endothelial growth factor, VEGF）对树突状细胞（dendritic cell, DC）功能及其分化的影响,针对VEGF基因设计siRNA（small interfering RNA, siRNA),采用脂质体转染法以100 nmol/L最佳转染浓度导入MCF-7乳腺癌细胞（siRNA组）,以脂质体Lipofectamine　2000TM转染MCF-7 乳腺癌细胞培养上清培养正常DC作为对照（对照组）,采用ELISA法检测经siRNA 干扰VEGF基因后的MCF-7 乳腺癌细胞分泌的VEGF因子含量, Western 印迹检测VEGF蛋白表达,以探讨siRNA的基因沉默效果;以siRNA组和对照组培养上清分别培养外周血单个核细胞,用流式细胞仪检测所诱导DC表型CD1a、CD80、CD83、CD86和HLA-DR的表达,用MTT法检测转染前后两组DC 诱导的细胞毒性T淋巴细胞（cytotoxic T lymphocyte, CTL）对MCF-7细胞的细胞毒作用.结果显示,MCF-7 乳腺癌细胞培养上清能明显抑制正常DC分化成熟及抗原递呈能力,干扰VEGF基因后MCF-7 乳腺癌细胞培养上清对DC的影响明显降低,CD80、CD83、CD86和HLA-DR的表达较对照组显著升高,而CD1a表达下降（P＜0.01）.转染前后DC 诱导的CTL对MCF-7细胞的杀伤活性有明显差异（P＜0.01）.由此可见,siRNA可靶向抑制MCF-7乳腺癌细胞VEGF的表达,下调VEGF后的MCF-7 细胞上清对DC分化成熟及功能的抑制作用明显降低,从而推测VEGF在肿瘤的发生、发展和免疫抑制方面可能起着重要的作用.     

siRNA抑制c-myc基因的表达对宫颈癌细胞增殖的影响

目的:利用siRNA(small interference RNA)技术研究c-myc基因的对宫颈癌HeLa细胞增殖的影响.方法:依据Promega公司在网上提供的设计软件,设计针对c-myc基因的siRNA,合成DNA模板,体外转录合成siRNA.通过阳离子聚合物jet-SITM-ENDO将合成的siRNA转染入HeLa细胞,以未转染细胞以及错义序列siRNA-scr转染细胞为对照.用细胞计数法检测siRNA对HeLa细胞增殖的影响.流式细胞法检测细胞周期及蛋白表达的变化,RT-PCR法比较转染前后c-myc mRNA表达水平的变化.结果:细胞计数法结果显示,转染24h后c-myc基因siRNA明显抑制MCF-7细胞增殖,转染48h后,抑制效率稳定.c-myc基因siRNA转染后能有效地抑制HeLa细胞的增殖,阻滞细胞周期于G0/G1期,siRNA转染组c-myc mRNA、蛋白的表达量明显低于空白对照组、错义序列组.结论:体外转录合成的siRNA可有效降低HeLa细胞c-myc基因的表达,抑制细胞增殖.     

Survivin基因RNA干扰对肺癌细胞凋亡及增殖的影响

目的:探讨Survivin表达对肺鳞癌细胞的凋亡和增殖的影响.方法:利用siRNA阻抑人肺鳞癌细胞内survivin基因的表达,用RT-PCR和Western Blotting法分析survivin基因mRNA和蛋白的表达,流式细胞术检测细胞凋亡率,细胞集落形成实验检测细胞增殖.结果:(1)Survivin在肺癌细胞中表达.转染Survivin siRNA可在RNA和蛋白水平阻断其表达;(2)转染Survivin siRNA的肺癌细胞凋亡率显著增加;(3)转染Survivin siRNA的肺癌细胞的集落形成率显著降低.结论:阻断Survivin表达可通过增加细胞凋亡率和降低细胞增殖增加肺鳞癌细胞的放疗敏感性.     

利用小干涉RNA抑制肿瘤细胞MCF-7中NF-IL6的表达

RNA干扰被证明是-项能有效而特异地抑制基因表达的新技术。转录因子NF-IL6特异地在肿瘤组织中过量表达,许多报道表明抑制它的功能对肿瘤治疗有利。构建能够沉默转录因子NF-IL6表达的小干涉RNA（siRNA）质粒,转染肿瘤MCF-7细胞后,用Western印迹法和荧光酶活性实验检测NF-IL6表达水平和转录活性的改变。结果发现NF-IL6的表达水平被下调80％,转录激活能力降低了60％,转染细胞内部出现大量空洞,细胞增殖停滞。     

下调RALA表达抑制人白血病K562细胞迁移和侵袭

目的 研究小干扰RNA（siRNA）抑制v-ral 白血病致病因子RALA基因表达对人白血病K562细胞迁移和侵袭的影响.方法 利用LipofectamineTM 2000将化学合成的RALA siRNA转染体外培养的K562细胞,Real-time PCR检测细胞内RALA mRNA的表达水平;Western印迹检测细胞内RALA蛋白的表达水平;Boyden趋化小室实验检测细胞体外迁移和侵袭能力.结果与随机对照组相比,转染48 h后,RALA siRNA显著下调K562细胞内RALA mRNA和蛋白的表达（P＜0.05）.与随机对照组相比,转染RALA siRNA的K562细胞迁移和侵袭能力显著降低（P＜0.05）.结论 癌基因RALA在人白血病K562细胞迁移和侵袭过程中发挥重要作用,通过siRNA下调RALA的表达可抑制K562细胞迁移和侵袭能力.     

不同分化阶段树突状细胞肌动蛋白微丝结合蛋白的表达变化

研究不同分化阶段树突状细胞(dendritic cells,DCs)重要肌动蛋白微丝结合蛋白的表达变化。人外周血经密度梯度离心和免疫磁珠法分离获得CD14+单核细胞,用细胞因子将单核细胞(monocytes,MOs)诱导分化为未成熟DCs(immature DCs,im DCs)和成熟DCs(mature DCs,m DCs)。分别提取不同分化阶段DCs的总蛋白和总RNA,实时定量PCR和蛋白质芯片检测部分细胞骨架微丝(filament actin,F-actin)结合蛋白的在基因和蛋白水平的表达变化。单核细胞经im DCs向m DCs分化的过程中,一些F-actin的单体隔离蛋白、加帽蛋白、交联蛋白、解聚蛋白和成核蛋白在基因和蛋白水平发生了不同程度的上调或下调。一些重要的F-actin结合蛋白在DCs不同分化阶段具有不同的表达水平,DCs的结构和功能受到这些蛋白的协同作用和精密调控,是细胞形态发生显著变化的结构基础,这对于深入理解DCs的免疫调节功能来说具有重要意义。     

Txnip基因siRNA慢病毒表达质粒构建及促进猪前体脂肪细胞分化

硫氧还蛋白互作蛋白(thioredoxin interacting protein, Txnip)是一种氧化还原调节蛋白质,与硫氧还蛋白结合并抑制其活性,调节细胞氧化还原状态,影响细胞多种生理过程,然而其在猪脂肪细胞分化中的作用尚不明确。本文设计合成3对靶向猪Txnip基因的shRNA寡核苷酸,分别连接于重组慢病毒载体pGLV_3/H_1/GFP+Puro构建siRNA表达质粒。测序验证后,与包装质粒共转染293T细胞,获得滴度1×10~8 pfu/mL的慢病毒干扰质粒。以MOI值100转染原代培养猪前体脂肪细胞,转染率均达80%以上,其中Txnip-shRNA-2转染细胞Txnip基因沉默率达75%。转染Txnip-shRNA-2的猪前体脂肪细胞用成脂分化培养液诱导后,每隔1 d检测细胞成脂分化及相关基因表达。结果发现,其分化比阴性对照质粒转染或未转染细胞显著增强(P<0.05),PPARγ和FAS mRNA表达水平显著提高(P<0.05)。本文构建siRNA慢病毒表达质粒能有效干扰猪Txnip基因表达,Txnip表达沉默可通过上调PPARγ表达促进猪前体脂肪细胞分化。本研究提示,Txnip可能是猪脂肪细胞分化的抑制因子。     

慢病毒介导神经生长因子过表达诱导脐带间充质干细胞向神经元样分化

目的探讨神经生长因子(NGF)过表达慢病毒转染脐带间充质干细胞(UMSCs)对细胞分化的影响。方法分离培养UMSCs,流式细胞术鉴定后利用慢病毒载体感染细胞,使其过表达NGF,72h后,通过免疫荧光检测NGF和GFP的表达,Western blot检测NGF蛋白表达水平,ELISA法检测细胞上清液NGF的含量,qRT-PCR检测相关神经因子基因的表达。结果流式细胞术显示细胞表面CD105、CD90、CD73阳性而CD34、CD45、CD19和CD14阴性,鉴定为脐带间充质干细胞。慢病毒转染后细胞NGF和GFP阳性,细胞内NGF和培养液中b-NGF含量都显著性增加,NGF、nestin、GFAP、MAP2及tubulin等mRNA的表达显著性增加。结论神经生长因子过表达慢病毒转染脐带间充质干细胞会促使细胞向神经元样细胞分化,可应用于后续研究。     

小鼠胚胎干细胞向脂肪细胞分化过程中PPARγ2基因的表达模式

将PPARγ2基因启动子和报告基因荧光素酶相连接克隆于特定载体构建成表达质粒,电穿孔转染小鼠ES细胞,筛选阳性克隆.诱导ES细胞向脂肪细胞分化,通过定量检测荧光素酶活性跟踪PPARγ2基因的表达情况,以此研究脂肪细胞分化过程中该基因的表达模式.结果显示PPARγ2基因在未分化的ES细胞和EB形成的前两天中不表达,从EB形成的第3天开始表达,直至脂肪细胞分化完成.该基因在已完成分化的脂肪细胞中的表达远强于在分化中的前脂肪细胞中的表达.首次报道了从小鼠ES细胞到脂肪细胞分化过程中PPARγ2基因的表达模式,支持了PPARγ2基因为脂肪组织特异性表达基因的已有报道,并为脂肪细胞分化机理研究提供了线索.     

Role of CD2-associated protein in albumin overload-induced apoptosis in podocytes

Proteinuria is a well-established exacerbating factor of chronic kidney diseases. However, the harmful effects of protein overload on podocytes and the underlying mechanisms are still poorly understood. In the present study, we examined the effects of high concentrations of albumin on podocytes and investigated the role of CD2AP (CD2-associated protein) in albumin overload-induced podocyte apoptosis. Conditionally immortalized mouse podocytes were cultured in vitro and treated with different concentrations of BSA. In addition, CD2AP eukaryotic expression vector or siRNA (small interfering RNA) was transfected into podocytes before they were exposed to BSA. Podocyte apoptosis, expressions of active caspase-3 (p17) and CD2AP, and the distribution of F-actin cytoskeleton were detected by flow cytometry, Western-blot analysis and fluorescent staining respectively. It was found that exposure of podocytes to BSA induced podocyte apoptosis in a concentration-dependent manner that was accompanied by up-regulation of active caspase-3, the disruption of F-actin cytoskeleton, and decreased expression of CD2AP. Transfection of CD2AP eukaryotic expression vector into podocytes increased CD2AP expression, partially restored F-actin distribution, blocked active caspase-3 expression and inhibited podocyte apoptosis. In contrast, transfection of CD2AP siRNA deteriorated the above changes induced by BSA. It is concluded that protein overload induces podocyte apoptosis via the down-regulation of CD2AP and subsequent disruption of cytoskeleton of podocytes, and CD2AP may play an important role in protein overload-induced podocyte injury.     

Downregulation of CD2-associated protein impaired the physiological functions of podocytes

Emerging evidences show that CD2-associated protein (CD2AP) is involved in podocyte injury and the pathogenesis of proteinuria. However, the exact molecular mechanism by which CD2AP exerts its biological function is elusive. We knocked down CD2AP gene by target siRNA in conditionally immortalized mouse podocytes, which showed lowered cell adhesion and spreading ability (P < 0.05). At the same time, cell cycle was arrested in G2/M phase (P < 0.05), and pathologic nuclear division could easily be seen in CD2AP siRNA-transfected podocytes. The proliferation of podocytes were also inhibited significantly by CD2AP siRNA transfection (P < 0.05). Further study revealed disordered distributions of F-actin, as well as lowered nephrin expression and phosphorylation in podocytes. These data suggest that CD2AP may play a crucial role in maintaining the normal function of podocytes and lowered CD2AP causes podocyte injury by disrupting the cytoskeleton and disturbing the nephrin-CD2AP signaling pathway.     

CD2-associated protein/phosphoinositide 3-kinase signaling has a preventive role in angiotensin II-induced podocyte apoptosis

Angiotensin II (Ang II) works as a paracrine or autocrine cytokine agent to regulate renal functions and promotes podocytes dysfunction directly or indirectly, causing proteinuria. The glomerular slit diaphragm (SD) serves as a size-selective barrier and is linked to the actin-based cytoskeleton by adaptor proteins, including CD2-associated protein (CD2AP). Therefore, damages to CD2AP affect not only the function of the SD, but also directly disrupt the podocyte cytoskeleton, leading to proteinuria. In addition, CD2AP can facilitate the nephrin-induced phosphoinositide 3-kinase (PI3-K)/Akt signaling, which protects podocytes from apoptosis. Here we found that CD2AP staining was located diffusely but predominantly in the peripheral cytoplasm and CD2AP co-localized with nephrin in mouse podocytes; however, Ang II decreased CD2AP staining diffusely and induced a separation from concentrated nephrin. Ang II notably reduced CD2AP expression in time- and concentration-dependent manners, and this was significantly recovered by losartan. Ang II induced podocyte apoptosis in time- and concentration-dependent manners in TUNEL and FACS assays. LY294002, a PI3-K inhibitor, further reduced CD2AP expression and increased podocyte apoptosis, which was augmented by siRNA for CD2AP. Thus, Ang II induces the relocalization and reduction of CD2AP via AT1R, which would cause podocyte apoptosis by the suppression of CD2AP/PI3-K signaling.     

The Directed Differentiation of Human iPS Cells into Kidney Podocytes

The loss of glomerular podocytes is a key event in the progression of chronic kidney disease resulting in proteinuria and declining function. Podocytes are slow cycling cells that are considered terminally differentiated. Here we provide the first report of the directed differentiation of induced pluripotent stem (iPS) cells to generate kidney cells with podocyte features. The iPS-derived podocytes share a morphological phenotype analogous with cultured human podocytes. Following 10 days of directed differentiation, iPS podocytes had an up-regulated expression of mRNA and protein localization for podocyte markers including synaptopodin, nephrin and Wilm’s tumour protein (WT1), combined with a down-regulation of the stem cell marker OCT3/4. In contrast to human podocytes that become quiescent in culture, iPS-derived cells maintain a proliferative capacity suggestive of a more immature phenotype. The transduction of iPS podocytes with fluorescent labeled-talin that were immunostained with podocin showed a cytoplasmic contractile response to angiotensin II (AII). A permeability assay provided functional evidence of albumin uptake in the cytoplasm of iPS podocytes comparable to human podocytes. Moreover, labeled iPS-derived podocytes were found to integrate into reaggregated metanephric kidney explants where they incorporated into developing glomeruli and co-expressed WT1. This study establishes the differentiation of iPS cells to kidney podocytes that will be useful for screening new treatments, understanding podocyte pathogenesis, and offering possibilities for regenerative medicine.     

Marker expression, behaviors, and responses vary in different lines of conditionally immortalized cultured podocytes

The state-of-the-art cultured podocyte is conditionally immortalized by expression of a temperature-sensitive mutant of the SV40 large-T antigen. These cultures proliferate at 33°C and differentiate at 37°C into arborized cells that more closely resemble in vivo podocytes. However, the degree of resemblance remains controversial. In this study, several parameters were measured in podocyte cell lines derived from mouse (JR, KE), human (MS), and rat (HK). In all lines, the quantities of NEPH1 and podocin proteins and NEPH1 and SYNPO mRNAs were comparable to glomeruli, while synaptopodin and nephrin proteins and NPHS1 and NPHS2 mRNAs were <5% of glomerular levels. Expression of Wilms' tumor-1 (WT1) mRNA in mouse lines was comparable to glomeruli, but rat and human lines expressed little WT1. Undifferentiated human and mouse lines had similar proliferation rates that decreased after differentiation, while the rate in rat cells remained constant. The motility of different lines varied as measured by both general motility and wound-healing assays. The toxicity of puromycin aminonucleoside was MS ～ JR > KE, and of doxorubicin was JR ～ KE > MS, while HK cells were almost unaffected. Process formation was largely a result of contractile action after formation of lamellipodia. These findings demonstrate dramatic differences in marker expression, response to toxins, and motility between lines of podocytes from different species and even between similarly-derived mouse lines.     

Protosappanin‐A and oleanolic acid protect injured podocytes from apoptosis through inhibition of AKT‐mTOR signaling

Protosappanin‐A (PrA) and oleanolic acid (OA), which are important effective ingredients isolated from Caesalpinia sappan L., exhibit therapeutic potential in multiple diseases. This study focused on exploring the mechanisms of PrA and OA function in podocyte injury. An in vitro model of podocyte injury was induced by the sC5b‐9 complex and assays such as cell viability, apoptosis, immunofluorescence, quantitative real‐time polymerase chain reaction, and western blot were performed to further investigate the effects and mechanisms of PrA and OA in podocyte injury. The models of podocyte injury were verified to be successful as seen through significantly decreased levels of nephrin, podocin, and CD2AP and increased level of desmin. The sC5b‐9‐induced podocyte apoptosis was inhibited in injured podocytes treated with PrA and OA, accompanied by increased protein levels of nephrin, podocin, CD2AP, and Bcl2 and decreased levels of desmin and Bax. The p‐AKT/p‐mTOR levels were also reduced by treatment of PrA and OA while AKT/mTOR was unaltered. Further, the effects of PrA and OA on injured podocytes were similar to that of LY294002 (a PI3K‐AKT inhibitor). PrA and OA were also seen to inhibit podocyte apoptosis and p‐AKT/p‐mTOR levels induced by IGF‐1 (a PI3K‐AKT activator). Our data demonstrate that PrA and OA can protect podocytes from injury or apoptosis, which may occur through inhibition of the abnormal activation of AKT‐mTOR signaling.     

BMP Signaling and Podocyte Markers Are Decreased in Human Diabetic Nephropathy in Association With CTGF Overexpression

Diabetic nephropathy is characterized by decreased expression of bone morphogenetic protein-7 (BMP-7) and decreased podocyte number and differentiation. Extracellular antagonists such as connective tissue growth factor (CTGF; CCN-2) and sclerostin domain-containing-1 (SOSTDC1; USAG-1) are important determinants of BMP signaling activity in glomeruli. We studied BMP signaling activity in glomeruli from diabetic patients and non-diabetic individuals and from control and diabetic CTGF^+/+ and CTGF^+/− mice. BMP signaling activity was visualized by phosphorylated Smad1, -5, and -8 (pSmad1/5/8) immunostaining, and related to expression of CTGF, SOSTDC1, and the podocyte differentiation markers WT1, synaptopodin, and nephrin. In control and diabetic glomeruli, pSmad1/5/8 was mainly localized in podocytes, but both number of positive cells and staining intensity were decreased in diabetes. Nephrin and synaptopodin were decreased in diabetic glomeruli. Decrease of pSmad1/5/8 was only partially explained by decrease in podocyte number. SOSTDC1 and CTGF were expressed exclusively in podocytes. In diabetic glomeruli, SOSTDC1 decreased in parallel with podocyte number, whereas CTGF was strongly increased. In diabetic CTGF^+/− mice, pSmad1/5/8 was preserved, compared with diabetic CTGF^+/+ mice. In conclusion, in human diabetic nephropathy, BMP signaling activity is diminished, together with reduction of podocyte markers. This might relate to concomitant overexpression of CTGF but not SOSTDC1. (J Histochem Cytochem 57:623–631, 2009)     

Nephrin phosphorylation regulates podocyte adhesion through the PINCH-1-ILK-α-parvin complex

Nephrin, a structural molecule, is also a signaling molecule after phosphorylation. Inhibition of nephrin phosphorylation is correlated with podocyte injury. The PINCH-1-ILK-α-parvin (PIP) complex plays a crucial role in cell adhesion and cytoskeleton formation. We hypothesized that nephrin phosphorylation influenced cytoskeleton and cell adhesion in podocytes by regulating the PIP complex. The nephrin phosphorylation, PIP complex formation, and F-actin in Wistar rats intraperitoneally injected with puromycin aminonucleoside were gradually decreased but increased with time, coinciding with the recovery from glomerular/podocyte injury and proteinuria. In cultured podocytes, PIP complex knockdown resulted in cytoskeleton reorganization and decreased cell adhesion and spreading. Nephrin and its phosphorylation were unaffected after PIP complex knockdown. Furthermore, inhibition of nephrin phosphorylation suppressed PIP complex expression, disorganized podocyte cytoskeleton, and decreased cell adhesion and spreading. These findings indicate that alterations in nephrin phosphorylation disorganize podocyte cytoskeleton and decrease cell adhesion through a PIP complex-dependent mechanism. [BMB Reports 2013; 46(4): 230-235]     

The Expression and Significance of Neuronal Iconic Proteins in Podocytes

Growing evidence suggests that there are many common cell biological features shared by neurons and podocytes; however, the mechanism of podocyte foot process formation remains unclear. Comparing the mechanisms of process formation between two cell types should provide useful guidance from the progress of neuron research. Studies have shown that some mature proteins of podocytes, such as podocin, nephrin, and synaptopodin, were also expressed in neurons. In this study, using cell biological experiments and immunohistochemical techniques, we showed that some neuronal iconic molecules, such as Neuron-specific enolase, nestin and Neuron-specific nuclear protein, were also expressed in podocytes. We further inhibited the expression of Neuron-specific enolase, nestin, synaptopodin and Ubiquitin carboxy terminal hydrolase-1 by Small interfering RNA in cultured mouse podocytes and observed the significant morphological changes in treated podocytes. When podocytes were treated with Adriamycin, the protein expression of Neuron-specific enolase, nestin, synaptopodin and Ubiquitin carboxy terminal hydrolase-1 decreased over time. Meanwhile, the morphological changes in the podocytes were consistent with results of the Small interfering RNA treatment of these proteins. The data demonstrated that neuronal iconic proteins play important roles in maintaining and regulating the formation and function of podocyte processes.