小窝蛋白-1mRNA在紫外线诱导的大鼠白内障的晶状体中的表达及意义

目的研究紫外线照射对小窝蛋白-1mRNA在大鼠晶状体中的表达量的影响。方法50只大鼠的晶状体随机分为A组（对照组25只）,B组（UV照射组25只）于MEM培养液中培养8h。实验组：紫外线照射晶状体30min后,加入MEM培养液,于37℃下,置5％C02培养箱中培养,分别在加入培养液后〈1h、6h、12h、24h、48h时,应用荧光realtimelit-PCR技术检测晶状体中小窝蛋白-1的表达量,对照组不照射,与同等条件下用同样的方法检测小窝蛋白-1的表达量。结果紫外线照射30min后,测得的小窝蛋白-1mRNA表达水平随着时间的延长有逐渐下降的趋势（P〈0．05）。结论紫外线照射对鼠晶状体上皮细胞产生影响,并导致细胞小窝蛋白-1表达量减少,小窝蛋白-1的减少在氧化性白内障的发生中有一定作用,小窝蛋白-1在晶状体上皮细胞膜上的表达减少。推测小窝蛋白-1对维持白内障晶状体透明具有保护意义。     

Caveolins in the repair phase of acute renal failure after oxidative stress

Ischaemia-reperfusion and toxic injury are leading causes of acute renal failure (ARF). Both of these injury initiators use secondary mediators of damage in oxygen-derived free radicals. Several recent publications about ischaemia-reperfusion and toxin-induced ARF have indicated that plasma membrane structures called caveolae, and their proteins, the caveolins, are potential participants in protecting or repairing renal tissues. Caveolae and caveolins have previously been ascribed many functions, a number of which may mediate cell death or survival of injured renal cells. This review proposes possible pathophysiological mechanisms by which altered caveolin-1 expression and localization may affect renal cell survival following oxidative stress.     

Biomechanical properties and innervation of the female caveolin-1-deficient detrusor

BACKGROUND AND PURPOSE

Caveolin-1-deficiency is associated with substantial urogenital alterations. Here, a mechanical, histological and biochemical characterization of female detrusors from wild-type and caveolin-1-deficient (KO) mice was made to increase the understanding of detrusor changes caused by lack of caveolae.

EXPERIMENTAL APPROACH

Length–tension relationships were generated, and we recorded responses to electrical field stimulation, the muscarinic receptor agonist carbachol and the purinoceptor agonist ATP. Tyrosine nitration and the contents of caveolin-1, cavin-1, muscarinic M₃ receptors, phospholipase C_β1, muscle-specific kinase (MuSK) and L-type Ca²⁺ channels were determined by immunoblotting. Innervation was assessed by immunohistochemistry.

KEY RESULTS

Bladder to body weight ratio was not changed, nor was there any change in the optimum circumference for force development. Depolarization- and ATP-induced stress was reduced, as was carbachol-induced stress between 0.1 and 3 µM, but the supramaximal relative (% K⁺) response to carbachol was increased, as was M₃ expression. The scopolamine-sensitive component of the electrical field stimulation response was impaired, and yet bladder nerves contained little caveolin-1. The density of cholinergic nerves was unchanged, whereas CART- and CGRP-positive nerves were reduced. Immunoblotting revealed loss of MuSK.

CONCLUSIONS AND IMPLICATIONS

Ablation of caveolae in the female detrusor leads to generalized impairment of contractility, ruling out prostate hypertrophy as a contributing factor. Cholinergic neuroeffector transmission is impaired without conspicuous changes in the density of cholinergic nerves or morphology of their terminals, but correlating with reduced expression of MuSK.     

小窝蛋白-1与肿瘤及其耐药机制

细胞膜内陷形成的细颈瓶状特殊膜结构小窝(caveolae),参与细胞分子运输、细胞黏附和信号转导在内的多种细胞活动。小窝蛋白(caveolin)是caveolae发挥生物学作用的重要组成蛋白,其三成员中的caveolin-1是细胞caveolae形成及各种信号分子聚集在caveolae上所必需。许多肿瘤中会出现caveolin-1表达异常,且在不同肿瘤组织中的表达变化具两面性,这种差异性可能与该组织恶变的特异性、各种生长因子与激素的表达状态及caveolin-1基因自身突变有关。caveolin-1也参与肿瘤细胞形成多药耐药性机制。该文介绍caveolin-1蛋白的结构特性和功能,重点阐述caveolin-1在细胞的恶性转化、恶性增殖、侵袭、转移及多药耐药中的作用。     

小凹介导氧化低密度脂蛋白跨内皮细胞转运

目的探讨小凹在氧化低密度脂蛋白（ox—LDL）逆向转运中的作用机制。方法用40μg／mLox—LDL处理人脐静脉内皮细胞（hUVEC）不同时间（0、6、12、24h）,高效液相色谱法观察细胞内脂质含量变化。用nocodazole阻滞cavolae运动后,荧光倒置显微镜观察FITC标记的氧化低密度脂蛋白受体（Lox-1）在细胞内的定位。将人脐静脉内皮细胞种植于transwell培养系统套3i／1．上层,分别用3种小凹阻滞剂carrageenan、filipin、no—codazole预处理细胞1h后加入40岬l／mLDiI荧光标记的ox—LDL（DiI—ox—LDL）于套皿上层孵育24h,取套皿下层液体用荧光分光光度计测荧光强度值。结果人脐静脉内皮细胞与ox—LDL孵育时,细胞荷脂呈时间依赖性增加。同时ox—LDL导致Lox-1向胞浆聚集,而nocodazole可阻止Lox-1向胞浆的聚集。小凹阻滞剂明显阻滞ox—LDL的跨内皮细胞转运分别达49％、72％和80％。结论内皮细胞可摄取ox—LDL而荷脂,其摄取ox—LDL的受体Lox-1定位于小凹中,小凹在介导ox—LDL的跨内皮细胞转运过程中起运载工具的作用。     

质膜脂微区--一种新发现的膜局限性结构域

脂微区为近年发现的广泛存在于质膜,主要由糖鞘脂、鞘磷脂、胆固醇及多GPI锚联蛋白组成的局限性结构域.该区具特殊的化学组成及特性,且富集许多重要的信号传递分子,在介导细胞信号传递过程中起重要作用.此外,脂微区与膜微囊之间既有区别又有联系.     

Increased expression of endothelial antigen PAL-E in human diabetic retinopathy correlates with microvascular leakage

Aims/hypothesis. The Pathologische Anatomie Leiden-Endothelium (PAL-E) antigen is a marker for loss of the blood-brain barrier function in brain tumours. It is endothelium specific and is associated with the endothelial plasmalemmal vesicles (caveolae) involved in transcellular transport. To test whether blood-retinal barrier loss in diabetic retinopathy is associated with cellular changes in the endothelium, the expression of antigen PAL-E in relation to microvascular leakage in human diabetic retinopathy was investigated. Methods. Immunohistochemical staining of frozen tissue sections of postmortem eyes obtained from 30 persons without and 41 persons with diabetes mellitus was carried out with monoclonal antibodies against PAL-E and CD31 and with antibodies against endogenous fibrinogen, albumin and IgG as indicators of vascular leakage. Results. Patchy or uniform microvascular PAL-E staining was observed in the retina of 17 of the 41 eyes of diabetic patients and in 2 of the 30 normal control eyes. In the diabetic eyes, PAL-E staining co-localized with microvascular staining for endogenous fibrinogen, albumin and IgG. Strong staining for PAL-E was observed in sites without blood-tissue barriers, like the choroid. Conclusions/interpretation. In microvessels with an intact blood-retina barrier the endothelial antigen PAL-E is absent. Its expression is increased in retinal vessels of patients with diabetic retinopathy and correlates with microvascular leakage of plasma proteins. This phenotypic shift involving an antigen associated with caveolae suggests that dysfunction of the endothelium forms the cellular basis for microvascular leakage in diabetic retinopathy, rather than passive endothelial damage. [Diabetologia (1999) 42: 596–602] Received: 10 September 1998 and in final revised form: 26 November 1998     

Viral modulation of lipid rafts and their potential as putative antiviral targets

Lipid rafts are ubiquitous in cells. They are identified as cholesterol and glycosphingolipid enriched microdomains on cellular membranes. They serve as platforms for cellular communications by functioning in signal transduction and membrane trafficking. Such structural organisation fulfils cellular needs for normal function, but at the same time increases vulnerability of cells to pathogen invasion. Viruses rely heavily on lipid rafts in basically every stage of the viral life cycle for successful infection. Various mechanisms of lipid rafts modification exploited by diverse viruses for attachment, internalisation, membrane fusion, genome replication, assembly and release have been brought to light. This review focuses on virus-raft interactions and how a wide range of viruses manipulate lipid rafts at distinct stages of infection. The importance of virus-raft interactions in viral infections has inspired researchers to discover and develop antivirals that target this interaction, such as statins, methyl-β-cyclodextrin, viperin, 25-hydroxycholesterol and even anti-malarial drugs. The therapeutic modulations of lipid rafts as potential antiviral intervention from in vitro and in vivo evidence are discussed herein.