瞬时受体电位阳离子通道蛋白6与肾脏疾病

瞬时受体电位阳离子通道蛋白6(transient receptor potential cation channel 6,TRPC6)是一个非选择性阳离子通道,定位于足细胞膜,为6次跨膜蛋白.TRPC6与裂孔隔膜分子nephrin以及podocin间存在相互作用,其共同组成裂孔隔膜复合体,突变TRPC6干扰了该复合体的功能,导致足细胞不能维持正常的生物学功能.研究发现TRPC6基因突变与遗传性和非遗传性肾脏疾病发病密切相关,突变的TRPC6可能通过使足细胞动力学发生改变以及足细胞数量减少而引起肾脏疾病.阻断TRPC6通道可能是一种治疗蛋白尿性肾脏疾病的有效方法 ,将给肾病患者带来长期的临床效应.     

TRPC6与肾脏疾病关系的研究进展

瞬时受体电位阳离子通道蛋白6（TRPC6）是由TRPC6基因编码的瞬时受体超家族成员之一,在人体内各组织或器官广泛表达,在肾小球足细胞也有表达。TRPC6与podocin、nephrin、ACTN4及CD2AP等多种裂孔隔膜（SD）蛋白相互作用共同维系肾小球足细胞的结构及功能。多因素作用导致肾小球足细胞损伤引起SD的足突融合是肾脏疾病最主要的形态学改变。该文就TRPC6生物学功能及其对肾脏疾病的影响作一简述。     

钙神经蛋白及瞬时受体电位阳离子通道蛋白6对足细胞骨架的影响研究进展

原发性肾病综合征蛋白尿的形成是由于肾小球滤过屏障受损所致,足细胞作为滤过屏障的关键部分,目前已被认为是参与尿蛋白产生及病情进展的关键细胞,足细胞骨架的结构和功能完整是其发挥生理功能的前提条件.以肌动蛋白为中心的细胞骨架损伤是各种因素作用于足细胞引起足突融合的“共同的最后道路”.该文对裂孔隔膜蛋白瞬时受体电位阳离子通道蛋白6(transient receptor potential cation channel 6,TRPC6)、钙神经蛋白(calcineurin,CaN)及其相互作用关系对细胞骨架的影响进行综述.     

瞬时受体电位阳离子通道蛋白6在肾脏的表达

目的探讨瞬时受体电位阳离子通道蛋白6（TRPC6）在正常人、小鼠和大鼠肾组织及小鼠足细胞系（MPC5）的表达和分布,为研究TRPC6在肾脏的功能及其与足细胞分子间的关系奠定基础。方法1.应用免疫组织化学方法观察TRPC6在正常人、小鼠和大鼠肾组织及MPC5分布。2.通过反转录酶-聚合酶链反应（RT-PCR）检测TRPC6在小鼠肾组织和MPC5表达。3.应用免疫蛋白印迹检测TRPC6在正常人、小鼠和MPC5表达。结果1.TRPC6在正常人肾小球呈弱表达,在肾小管和肾血管表达较强,在小鼠和大鼠主要沿肾小球毛细血管袢和系膜区分布,肾间质也有少许表达。TRPC6在MPC5的荧光染色为阳性,在分化态细胞主要分布于胞膜表面。2.在小鼠肾组织及MPC5均检测到特异性TRPC6的PCR产物条带。3.在正常人、小鼠肾组织及MPC5均检测到特异性的相对分子质量为106的TRPC6蛋白条带。结论TRPC6在正常人、小鼠和大鼠肾小球均有表达,在mRNA及蛋白水平均证实MPC5能表达TRPC6,为从离子通道的角度利用MPC5探讨蛋白尿发生的分子机制奠定基础。     

儿童原发性肾病综合征肾组织瞬时受体电位阳离子通道蛋白6表达及意义

目的探讨原发性肾病综合征(PNS)患儿肾组织中瞬时受体电位阳离子通道蛋白6(TRPC6)的表达与足细胞损伤的关系及其临床意义。方法获取18例PNS患儿的肾组织,常规切片染色光镜观察肾脏组织病理改变,电镜观察足细胞的结构变化,分别用q PCR和免疫组化测定组织中TRPC6 m RNA和蛋白的表达,并将TRPC6 m RNA表达分别与血清白蛋白(Alb)、肌酐(Cr)、三酰甘油(TG)、胆固醇(Tch)、补体C3水平及24 h尿蛋白定量和评估的肾小球滤过率(e GFR)进行相关性分析。结果 PNS患儿肾组织中TRPC6蛋白表达较对照组上调,差异有统计学意义(P0.05)。PNS患儿肾组织中TRPC6 m RNA的相对表达量与肾组织TRPC6蛋白表达呈显著正相关(r=0.508,P0.05),与血清Alb、Cr、TG、Tch、补体C3、e GFR水平以及24 h尿蛋白定量无相关性(P0.05)。结论 PNS患儿的病理类型仍以足细胞病变为主,其肾小球足细胞中TRPC6蛋白表达升高。TRPC6检测可能有助于足细胞病变诊断。     

肾小球足细胞生理功能与致损伤因素

近年来对足细胞在维持肾小球滤过屏障和肾功能的作用研究逐步深入.研究证实,足细胞是多种肾小球疾病免疫或非免疫损伤的靶标,多种类型的肾小球疾病均特征性地表现为足细胞异常.足细胞损伤往往会引起肾小球滤过膜结构和功能异常,从而导致蛋白尿的产生.深入认识足细胞的生理功能及致损伤因素,对于临床有效防治肾小球损伤性疾病有重要意义.     

过氧化物酶体增殖物活化受体γ激动剂减轻血管紧张素Ⅱ诱导的肾小球足细胞损伤作用

目的1.探讨氧化应激在血管紧张素Ⅱ(AngⅡ)诱导的蛋白尿和肾小球足细胞损伤中的作用;2.观察过氧化物酶体增殖物活化受体γ(PPARγ)激动剂罗格列酮对AngⅡ诱导的蛋白尿和肾小球足细胞损伤的抑制作用。方法雄性C57BL/6小鼠24只随机分为:健康对照组、AngⅡ模型组、Tempol治疗组和罗格列酮治疗组。尿8-isoprostane和清蛋白采用酶联免疫吸附试验(ELISA)检测;应用透射电镜观察肾小球足细胞损伤;实时定量聚合酶链式反应(RT-PCR)检测肾组织中nephrin和podocin表达。结果1.AngⅡ灌注后尿中8-isoprostane和清蛋白排泄分别是健康对照组的5.45倍和16.65倍;肾小球足细胞出现广泛足突融合;肾组织中nephrin和podocin表达显著降低,分别是健康对照组的56%和49%。2.Tempol治疗后尿8-isoporstane和清蛋白排泄分别降低68%和77%;肾小球足细胞损伤明显减轻;肾组织中nephrin和podocin表达显著增加,分别是模型组的1.43倍和1.51倍。3.罗格列酮治疗后尿中8-isoprostane和清蛋白排泄分别降低57%和74%;AngⅡ诱导的肾小球足细胞损伤在罗格列酮治疗后明显好转;肾组织中nephrin和podocin表达亦显著增加,是模型组的2.05倍和1.58倍。结论AngⅡ通过诱导氧化应激而导致蛋白尿和肾小球足细胞损伤;PPARγ激动剂通过抑制氧化应激阻断AngⅡ诱导的蛋白尿和肾小球足细胞损伤。     

肾小球足细胞骨架结构的适应性应变

肾小球足细胞肌动蛋白骨架是一个复杂的网络结构,其形态结构的稳定性与裂孔隔膜、足突顶端、足突基底等区域的相关蛋白分子密切相关,面对外力作用,在RhoA/Rho激酶信号通路、瞬时受体电位阳离子通道蛋白6(TRPC6)等参与下,足细胞骨架能在一定范围内进行适应性应变,以维护肾小球的正常滤过功能.     

肾小球足细胞内的蛋白质降解机制

足细胞在维系肾小球滤过屏障的选择通透性方面有重要作用,而足细胞损伤导致的蛋白尿则足肾小球疾病的重要标志足细胞胞质内中主要有2种蛋白降解途径:自噬系统和泛索蛋白酶体系统.了解蛋白降解机制变化对足细胞的影响,期望为今后肾脏疾病的治疗提供可靠依据.     

蛋白尿的发生机制研究进展

蛋白尿的主要发生机制是肾小球滤过增加和（或）肾小管重吸收障碍。近年来,对肾小球滤过屏障研究取得显著进展,内皮细胞表层和足细胞下间隙成为肾小球滤过屏障新组分,发现越来越多的足细胞分子与蛋白尿关系密切,主导或者参与了肾小球疾病的发生。     

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??Proteinuria is the most common manifestations of pediatric renal diseases. During the development and process of proteinuria??podocytes have played a very important role. A growing number of podocyte-related molecules have been confirmed to be associated with the molecular mechanisms of proteinuria. However??there are few studies focusing on the role of podocyte-related molecules in the diagnosis and treatment of proteinuria. Due to the lack of real transformation from bench to bed situation??the present paper will discuss the role of podocyte in the monitoring and treatment of proteinuria based on the podocytes’ role in mechanisms of proteinuria.     

活性维生素D及其类似物对足细胞的保护作用

1,25(OH)2D3产生不足是慢性肾脏病(CKD)的主要特征之一,不仅导致钙磷代谢异常及骨矿化障碍,而且加速肾疾病的进展。1,25(OH)2D3及其类似物可减轻CKD患者的蛋白尿,减轻动物模型足细胞的损伤、凋亡和脱落,促进裂孔隔膜蛋白的表达,维持肾小球滤过屏障的完整性。1,25(OH)2D3保护足细胞机制与抑制足细胞肾素-血管紧张素系统、阻断Wnt/β-Catenin和转化生长因子(TGF)-β1信号通路有关。     

乙型肝炎病毒相关性膜性肾病患儿足细胞缺失的研究

目的观察乙型肝炎病毒相关性膜性肾病（HBV—MN）患儿肾小球足细胞数量的变化及意义。方法以Wilms瘤蛋白1（wn）为足细胞核的特征性标记,通过免疫组织化学方法对19例经肾穿刺活检确诊为HBV．MN患儿及8例同期肾活检诊断为薄基底膜病（TBMD）的患儿（对照组）肾脏病理切片的足细胞进行特异性染色,采用Weibel-Gomez点计数方法测定单位肾小球足细胞绝对数目（Npodo）、足细胞相对密度（Nv）及单个肾小球毛细血管簇体积（V）,比较两组间差异,并分析其与血清免疫学检查、蛋白尿程度及肾组织病理改变等指标间的关系。结果①19例HBV—MN患儿的超微病理结果均显示存在不同程度的足突融合,3例有足突微绒毛化,4例出现足细胞肿胀,1例足细胞空泡变性,2例可见足细胞崩解;②HBV-MN患儿Npodo及Nv均较对照组显著下降（P〈0．01）;③Npodo的减少与肾小球中HBsAg的沉积强度相关,HBsAg免疫荧光强度≥（＋＋）患儿的平均Npodo明显低于荧光强度〈（＋＋）者（P〈0．01）;但Npodo及Nv的下降均与肾脏病变病理分期无显著相关性;④Nv减少与蛋白尿程度相关,24h尿蛋白定量〈2g患儿的Nv明显高于〉2g者（P〈0．05）;⑤肾小球足细胞数量与血清补体C3水平呈正相关（r=0．548,P=0．028）,而与血清白蛋白水平无显著相关性（r=-0．037,P=0．891）。结论HBV—MN患儿均存在不同程度的足细胞损伤、缺失,Npodo减少可能在HBV-MN的发病中起重要作用。     

Induction of podocyte-derived VEGF ameliorates podocyte injury and subsequent abnormal glomerular development caused by puromycin aminonucleoside

Our previous studies using puromycin aminonucleoside (PAN) established that podocyte damage leads to glomerular growth arrest during development and glomerulosclerosis later in life. This study examined the potential benefit of maintaining podocyte-derived VEGF in podocyte defense and survival after PAN injury using conditional transgenic podocytes and mice, in which human VEGF-A (hVEGF) transgene expression is controlled by tetracycline responsive element (TRE) promoter and reverse tetracycline transactivator (rtTA) in podocytes. In vitro experiments used primary cultured podocytes harvested from mice carrying podocin-rtTA and TRE-hVEGF transgenes, in which hVEGF can be induced selectively. Induction of VEGF in PAN-exposed podocytes resulted in preservation of intrinsic VEGF, α-actinin-4 and synaptopodin, antiapoptotic marker Bcl-xL/Bax, as well as attenuation in apoptotic marker cleaved/total caspase-3. In vivo, compared with genotype controls, PAN-sensitive neonatal mice with physiologically relevant levels of podocyte-derived VEGF showed significantly larger glomeruli. Furthermore, PAN-induced up-regulation of desmin, down-regulation of synaptopodin and nephrin, and disruption of glomerular morphology were significantly attenuated in VEGF-induced transgenic mice. Our data indicate that podocyte-derived VEGF provides self-preservation functions, which can rescue the cell after injury and preempt subsequent deterioration of the glomerulus in developing mice.     

Morphology of the kidneys in children with primary nephrotic syndrome (lipoid nephrosis) before and after hormone therapy, studied by biopsy (light and electron microscopy)]

Light and electron microscopies were employed to examine biopsy specimens from 15 children suffering from the primary nephrotic syndrome with minimal alterations in renal bodies. The studies were carried out at the height of the disease and in the stage of a clinical remission after prednisolone therapy. The author describes the development of ultrastructural changes in the glomerular filter, primarily of those in podocytes, under the conditions of highly selective proteinuria as well as during hormonal therapy that favours reparative processes and discontinuation of protein "leakage". It is assumed that the anionic layer of the glycocalyx of podocyte pedicles and l. rara ext. heparan sulfates of the basal membrane may play a role in the origin of selective proteinuria.     

亚溶量C5b-9与足细胞损伤及其信号传导的研究进展

膜性肾病的发病机制与亚溶量C5b-9(SC5b-9)诱导足细胞损伤有关.SC5b-9刺激足细胞产生的氧化剂、蛋白酶、前列腺素类、细胞外基质及各种细胞因子对足细胞有损伤作用.SC5b-9对足细胞的作用主要表现为引起足细胞凋亡、足细胞脱落以及对细胞周期的影响.MAPK通路在SC5b-9导致足细胞损伤中起到重要的作用.     

Molecular genetic analysis of podocyte genes in focal segmental glomerulosclerosis—a review

This review deals with podocyte proteins that play a significant role in the structure and function of the glomerular filter. Genetic linkage studies has identified several genes involved in the development of nephrotic syndrome and contributed to the understanding of the pathophysiology of glomerular proteinuria and/or focal segmental glomerulosclerosis. Here, we describe already well-characterized genetic diseases due to mutations in nephrin, podocin, CD2AP, alpha-actinin-4, WT1, and laminin β2 chain, as well as more recently identified genetic abnormalities in TRPC6, phospholipase C epsilon, and the proteins encoded by the mitochondrial genome. In addition, the role of the proteins which have shown to be important for the structure and functions by gene knockout studies in mice, are also discussed. Furthermore, some rare syndromes with glomerular involvement, in which molecular defects have been recently identified, are briefly described. In summary, this review updates the current knowledge of genetic causes of congenital and childhood nephrotic syndrome and provides new insights into mechanisms of glomerular dysfunction.