AQP4与脑水肿

水通道蛋白(AQPs)广泛分布于机体不同组织器官中,脑组织中的水通道蛋白主要为AQP4。AQP4蛋白主要在星型胶质细胞和室管膜细胞内表达,尤其在于毛细血管和软脑膜直接接触的胶质细胞上及血管周表达丰富,AQP4的分布特点与其功能密切相关,可能是脑脊液重吸收、渗透压调节、脑水肿形成等生理、病理过程的分子生物学基础。研究AQP4可为脑水肿及水代谢疾病提供分子水平的理论依据,同时为临床治疗脑水肿及水代谢疾病提供一种新途径。     

水通道蛋白亚型1-5在鼠鼻粘膜中表达及意义

目的 检测水通道蛋白（water channel protein；Aquaporin AQP）不同亚型在大鼠鼻粘膜组织中的分布及各亚型的组定位。探讨其组织水代谢障碍所致疾病的发生机制。方法 取20只成年Wistar大鼠，3％戊巴比妥钠腹腔麻醉，即刻取鼻粘膜组织，4％多聚甲醛固定，石蜡包埋。应用免疫组织化学技术检测鼻粘膜组织中水通道蛋白1、2、3、4、5的分布情况。结果 AQP1、4为1：1000，AQP3为1：300，AQP5为1：400的抗体浓度可以观察到它们在鼻粘膜组织不同部位稳定、清晰的染色反应。但AQP2使用1：50也未观察到染色，AQP1在基底膜反应清晰，AQP3在腺体内导管及胞浆被标记，AQP4在被覆上皮细胞膜、血管内皮表达清晰，AQP5在纤毛，浆液细胞胞浆广泛表达。结论 水通道蛋白1、3、4、5广泛分布在鼻粘膜不同部位，当某种水通道蛋白亚型表达出现异常时，可能会成为导致组织发生水代谢异常疾病的重要原因之一。     

水通道蛋白-4与脑水肿关系的研究

水通道蛋白(AQPs)是近年来研究水液代谢疾病的热点,水通道蛋白-4(AQP4)是美国科学家Agre教授于1994年分离发现的[1],它是水通道蛋白家族的一个成员.迄今为止,已从哺乳动物组织中鉴定中13种AQPs[2].脑组织中的AQP主要为AQP4.AQP4是分布于脑组织中的主要水通道蛋白.     

水通道蛋白1、5在肺出血新生大鼠肺组织中的表达

目的研究新生大鼠肺出血发生的过程中水通道蛋白1、5在肺中表达的变化和意义。方法将80只4～5 d龄新生SD大鼠分为4组,对照组1组和实验组3组,对照组为常温常氧6 h;实验组分别为低温缺氧1 h复温供氧2 h、低温缺氧2 h复温供氧2 h和低温缺氧4 h复温供氧2 h,用断头法处死大鼠后开胸取肺做病理切片和免疫组化染色。结果观察到随着低温缺氧时间的延长病理改变可从正常肺组织向着肺水肿、点状肺出血、局灶性肺出血至弥漫性肺出血的方向发展。水通道蛋白1(AQP 1)主要表达于胸膜脏层周围毛细血管内皮细胞腔膜面和基侧膜面以及脏层胸膜的间皮细胞,肺泡Ⅱ型上皮细胞顶膜面也有少量表达,AQP 1还存在于气管腔上皮细胞顶膜面和支气管黏膜下腺上皮细胞。水通道蛋白5(AQP 5)表达于Ⅰ型上皮细胞的顶膜。随着低温缺氧时间的延长,复温供氧后AQP 1在肺毛细血管内皮细胞表达明显下降,这种减少全肺均能观察到,肺泡Ⅰ型上皮细胞AQP 5的表达也一致减少。对应的病理改变为细胞炎症反应,肺水肿、肺泡腔及间质出血。结论 AQP 1、AQP 5与新生大鼠肺出血关系密切,AQP 1、AQP 5可能与肺水肿、肺出血的形成有关。通过调节AQP 1及AQP 5的表达可能预防新生儿肺出血的发生。     

肺水通道蛋白与慢性阻塞性肺疾病

<正>20世纪90年代初发现第一个水通道蛋白AQP1(aquaporin1),自此越来越多的水通道蛋白被发现,并且对水的跨膜转运有了新的了解和认知[1]。目前在哺乳动物体内体内发现的水通道蛋白有13种之多,AQP0-12[2]。而在肺组织中主要分布的有AQP1、AQP3、AQP4及AQP5,并且他们在肺水转运中起着不可或缺的作用,近年来的研究表明:肺水通道的异常表达与慢性阻塞性肺疾病的气道炎症、气道黏液高分     

应用MTT检测乙酰唑胺对卵巢癌细胞的抑制作用

卵巢癌患者大多伴有大量腹水,目前其病理机制尚不完全清楚。水通道蛋白1(AQP1)是Agre最早发现的水通道,它分布广泛,具有特异转运水的功能,与多种疾病的发生和发展密切相关,目前已成为众多学者研究的热点[1]。AQP-1与卵巢肿瘤的     

水通道蛋白1与麻醉相关研究进展

正水通道蛋白家族(AQPs)是一组对水有高度选择性的膜通道蛋白,它们在哺乳动物的组织和器官中广泛分布,至今已发现13种(AQP0-AQP12),其中水通道蛋白1(AQP1)[1]是最早被发现且目前研究最深入的水通道。目前已发现许多麻醉药物对机体重要器官的保护作用与AQP相关,本文就其与AQP1的研究进展进行综述。     

水通道蛋白AQP1、AQP3在神经鞘瘤中的表达

目的检测水通道13、在人外周神经肿瘤的表达。方法收集五例患者的神经鞘瘤组织,采用免疫组化方法检测AQP1、AQP3的表达。结果 AQP1、AQP3在神经鞘瘤组织中都有表达,AQP1主要表达在微血管中,AQP3在整个组织中广泛表达。结论首次发现AQP1在神经鞘瘤微血管中表达,可能参与肿瘤血管新生;AQP3在神经鞘瘤细胞广泛表达,可能通过增加肿瘤细胞膜的水通透性而促进肿瘤的生长及浸润。两种水通道蛋白表达量与肿瘤发生发展的关系尚待扩大标本例数结合临床资料进一步分析。     

水通道蛋白4在中枢神经系统疾病中的研究进展

水通道蛋白(aquaporins, AQPs)是一跨膜蛋白家族,主要调节体内水的转运,AQP4是水通道蛋白家族成员,在中枢神经系统主要表达于星形胶质细胞终足。近年来,AQP4在多种神经系统疾病发生发展中的作用机制备受关注,通过深入研究AQP4在中枢神经系统疾病中的变化,有助于在分子层面阐明疾病的发生机制,从而为中枢神经系统疾病的诊疗提供新的思路和方法。     

水通道蛋白9与消化系统疾病

水通道蛋白是一组对水有高选择性的跨膜转运蛋白,广泛分布在机体各组织,在水的分泌吸收、细胞内外水平衡等过程中起着重要作用。水通道蛋白9(AQP9)是水通道蛋白家族成员之一,是1998年发现的一种新的水通道蛋白亚型,现就AQP9的基本特点,在消化道的分布、表达,与疾病的关系作一     

Water channels encoded by mutant aquaporin-2 genes in nephrogenic diabetes insipidus are impaired in their cellular routing.

Congenital nephrogenic diabetes insipidus is a recessive hereditary disorder characterized by the inability of the kidney to concentrate urine in response to vasopressin. Recently, we reported mutations in the gene encoding the water channel of the collecting duct, aquaporin-2 (AQP-2) causing an autosomal recessive form of nephrogenic diabetes insipidus (NDI). Expression of these mutant AQP-2 proteins (Gly64Arg, Arg187Cys, Ser216Pro) in Xenopus oocytes revealed nonfunctional water channels. Here we report further studies into the inability of these missense AQP-2 proteins to facilitate water transport in Xenopus oocytes. cRNAs encoding the missense AQPs were translated with equal efficiency as cRNAs encoding wild-type AQP-2 and were equally stable. Arg187Cys AQP2 was more stable and Gly6-4Arg and Ser216Pro AQP2 were less stable when compared to wild-type AQP2 protein. On immunoblots, oocytes expressing missense AQP-2 showed, besides the wild-type 29 kDa band, an endoplasmic reticulum-retarded form of AQP-2 of approximately 32 kD. Immunoblots and immunocytochemistry demonstrated only intense labeling of the plasma membranes of oocytes expressing wild-type AQP-2. Therefore, we conclude that in Xenopus oocytes the inability of Gly64-Arg, Arg187Cys or Ser216Pro substituted AQP-2 proteins to facilitate water transport is caused by an impaired routing to the plasma membrane.     

Ultrastructural localization of aquaporin 4 and alpha1-syntrophin in the vascular feet of brain astrocytes

Aquaporin 4 (AQP4) is a recently discovered membrane bound water-selective channel and has been described at the light microscopic level to be predominantly expressed in the astrocytes of the brain, especially at the perivascular astrocyte endfoot processes. Alpha1-syntrophin, a member of dystrophin-associated protein, has also been reported at the light microscopic to be expressed level in the same site of astrocytes as AQP4 and interacts with other molecules through its PDZ domain. AQP4 expression has been reported to be absent at the sarcolemma and the perivascular astrocyte endfoot processes of alpha1-syntrophin knockout mice. Based on these observations, the molecular association between AQP4 and alpha1-syntrophin could be speculated. To test this hypothesis, we investigated the ultrasturctural localization of AQP4 and alpha1-syntrophin in the brain astrocytes by using double immunogold labeled electron microscopy. The results showed that AQP4 and alpha1-syntrophin colocalized frequently at the astrocyte membrane, especially at the perivascular astrocyte endfoot processes and suggested the presence of linkage between AQP4 and alpha1-syntrophin at the astrocyte plasma membrane.     

Urinary excretion of aquaporin-2 in pathological states of water metabolism

Aquaporin-2 (AQP-2) is an arginine vasopressin (AVP)-regulated water channel in renal collecting duct cells. Approximately 3 % of AQP-2 in collecting duct cells is excreted into urine. Urinary excretion of AQP-2 varies widely in different physiological conditions, and it has a positive correlation with plasma AVP levels. Urinary excretion of AQP-2 was significantly increased by the single injection of AVP in patients with central diabetes insipidus. The urinary excretion of AQP-2 was one-eighth over in patients with central diabetes insipidus and three times greater in patients with impaired water excretion than that in normal subjects. In a hypertonic saline test, the urinary excretion of AQP-2 promptly increased 6-12-fold in normal subjects, but remained low in patients with central diabetes insipidus. In addition, exaggerated urinary excretion of AQP-2 persisted after an acute water load in patients with impaired water excretion. These results indicate that urinary excretion of AQP-2 is a potent marker for the diagnosis of water metabolism disorders dependent on AVP.     

脂氧素A4对肺泡Ⅱ型上皮细胞水通道蛋白1,3,5的影响

目的 探讨脂氧素A4(LipoxirA4,LxA4)对脂多糖(lipopolysaccharide,LPS)攻击的大鼠肺泡Ⅱ型上皮细胞(typeⅡpenumonocyte,AT Ⅱ)水通道蛋白(aquaporin,AQP)1,3,5的影响.方法 每次取SPF级健康SD雄性大鼠,体质量200～250 g一只,对大鼠肺泡Ⅱ型上皮细胞进行分离、纯化,鉴定,得到纯度为≥90%的肺泡Ⅱ型上皮细胞,将细胞随机分为:①溶剂对照(乙醇,0.7μL/mL)组;②空白组(无血清的培养基不含任何药物);③LXA4(1×10-7moL/mL)组;④LPS(1μg/mL)组;⑤LPS+LXA4(1μg/mL LPS+1×10-7moL/mL LXA4)组.药物刺激4 h后用逆转录聚合酶链反应法(RT-PCR)检测大鼠肺泡Ⅱ型上皮细胞上AQP1,AQP3和AQP5的mRNA的表达,免疫组织化学方法(IHC)检测肺泡Ⅱ型上皮细胞上AQP1,AQP3和AQP5蛋白的表达.试验重复6次.采用方差分析进行统计学处理.结果 RT-PCR和免疫组织化学法结果显示,用1 μg/mL的LPS刺激肺泡Ⅱ型上皮细胞4 h后ATⅡ上AQP1,AOP3和AQP5的mRNA和蛋白表达较空白组明显减低(P＜0.01),而LPS+LXA4组中ATⅡ上AQP1,AQP3和AQP5的mRNA和蛋白表达较LPS模型组有明显增高(LPS+LXA4,AQP1:0.647±0.132,AQP3:0.900±0.856,AQP5:0.879±0.058;LPS.AQP1:0.297±0.133,AQP3:0.512±0.113,AQP5:0.647±0.110;P＜0.01),且LXA4组中ATⅡ上AQP1,AQP3和AQP5的mRNA和蛋白表达较空白组也有明显增高(LXA4,AQP1:0.539±0.142,AQP3:0.818±0.176,AQP5:0.841±0.066;Blank Control,AQP1:0.518±0.139;AQP3:0.138±0.136,AQP5:0.766±0.066;P＜0.01).结论 大鼠肺泡Ⅱ型上皮细胞上表达有AQP1,AQP3和AQP5,LXA4能促进脂多糖攻击的肺泡Ⅱ型上皮细胞上AQP1,AQP3和AQP5mRNA和蛋白表达上调.     

水通道蛋白-4在正常兔脊髓内的分布研究

目的明确正常兔脊髓水通道蛋白-4（AQP4）的表达分布规律，为进一步研究脊髓组织中水分子的运输及平衡调节提供理论依据。方法采用免疫组化技术检测AQP4在兔脊髓内的表达分布。结果AQP4在灰质的分布明显多于白质，主要为神经胶质细胞的细胞膜着色，脊髓中央管周围、软脊膜以及血管周围呈极性分布，邻近蛛网膜下腔、毛细血管内皮细胞和神经元的胶质细胞突起表达非常丰富。结论AQP4在兔脊髓内具有广泛的表达并且呈极性分布，主要集中在与水分子转运关系密切的部位，表明AQP4在脊髓内主要参与脊髓水代谢的调节。     

Effects of nitric oxide system and osmotic stress on Aquaporin-1 in the postnatal heart

Aquaporin-1 (AQP1) is expressed in the heart and its relationship with NO system has not been fully explored. The aims of this work were to study the effects of NO system inhibition on AQP1 abundance and localization and evaluate AQP1 S-nitrosylation in a model of water restriction during postnatal growth. Rats aged 25 and 50 days (n = 15) were divided in: R: water restriction; C: water ad libitum; RL: L-NAME (4 mg/kg day) + water restriction; CL: L-NAME + water ad libitum. AQP1 protein levels, immunohistochemistry and S-nitrosylation (colocalization of AQP1 and S-nitrosylated cysteines by confocal microscopy) were determined in cardiac tissue. We also evaluated the effects of NO donor sodium nitroprusside (SNP) on osmotic water permeability of cardiac membrane vesicles by stopped-flow spectrometry. AQP1 was present in cardiac vascular endothelium and endocardium in C and CL animals of both ages. Cardiac AQP1 levels were increased in R50 and RL50 and appeared in cardiomyocyte plasma membrane. No changes in AQP1 abundance or localization were observed in R25, but RL25 group showed AQP1 presence on cardiomyocyte sarcolemma. AQP1 S-nitrosylation was increased in R25 group, without changes in the 50-day-old group. Cardiac membrane vesicles expressing AQP1 presented a high water permeability coefficient and pretreatment with SNP decreased water transport. Age-related influence of NO system on AQP1 abundance and localization in the heart may affect cardiac water homeostasis during hypovolemic state. Increased AQP1 S-nitrosylation in the youngest group may decrease osmotic water permeability of cardiac membranes, having a negative impact on cardiac water balance.     

CLS meets the aquaporin family: clinical cases involving aquaporin systems.

Virtually all human cells incorporate aquaporins, or water channel proteins, into their cell membrane. Indeed, many cells produce several aquaporins, each adapted for a specific physiologic function. Thus, it is not surprising that aquaporin malfunctions are associated with numerous important clinical conditions. This article describes the clinical aspects of malfunctions in aquaporins or their regulation. Although water can diffuse across biological membranes (osmosis) without the aid of a transport system, researchers had predicted for decades that rapid reabsorption by renal tubule cells must be aided by a channel or pore. Yet, not until the 1990s were the first members of the aquaporin (AQP) family identified. Led by Dr. Peter Agre, recipient of the 2003 Nobel Prize in Chemistry, researchers have since amassed an astounding amount of information about AQPs and their function. For example, the flow rate of water through AQP1 is an extraordinary three billion water molecules per second per aquaporin channel, while a relative trickle of water crosses the hydrophobic lipid bilayer of cell membranes devoid of AQPs. Our understanding of renal physiology and pathophysiology has advanced greatly as we account for the subtle implications of various AQP systems. For example, nephrogenic diabetes insipidus (NDI), the inability to produce concentrated urine, can result from several different malfunctions in the hormonally controlled AQP2 system. The list of diseases known to involve AQPs now includes: early onset of cataracts, Sjogren's syndrome, cerebral and pulmonary edemas, cirrhotic liver development of ascites, and congestive heart failure (CHF).     

Anatomical and functional analysis of aquaporin 1, a water channel in primary afferent neurons

Aquaporin 1 (AQP1) is the archetypal member of a family of water channel proteins that contribute to water homeostasis in kidney, lung, and other tissues. Although there is limited evidence that aquaporins are expressed in the nervous system, AQP4 is expressed in glia and AQP9 is present on some neuronal and glial mitochondria. In the present study, we used immunohistochemistry to show that AQP1 is heavily expressed in a population of small diameter primary sensory neurons of dorsal root, trigeminal, and nodose ganglia. AQP1 immunoreactivity is abundant in DRG cell bodies and in both the peripheral and central branches of primary afferent neurons, and colocalizes with markers of nociceptors, notably substance P and IB4. AQP1 expression in DRG is first detectable at embryonic day 15.5, which corresponds to the developmental stage when the majority of fine cutaneous afferents penetrate the dorsal horn. Electron microscopy revealed dense membrane labeling of unmyelinated axons, a few fine diameter myelinated axons, and synaptic terminals in the superficial dorsal horn. Because this restricted and dense expression suggested that AQP1 contributes to nociceptive processing, we studied behavioral responses of wildtype and AQP1 -/- mice in a comprehensive battery of acute and persistent pain tests. We also used in vivo electrophysiology in wildtype and mutant mice to measure the responses of wide dynamic range neurons in lamina V of the dorsal horn to thermal stimulation before and after noxious stimulus-induced sensitization. To date we have not detected a differential phenotype suggestive of a functional contribution of AQP1 to nociceptive processing.     

A brief survey of aquaporins and their implications for renal physiology.

Aquaporins (AQPs) are an important family of proteins that efficiently channel water through the cell membranes. Although water can diffuse across biological membranes at measurable rates, physiologists had long predicted the existence of channels to facilitate rapid reabsorption of water by renal tubular cells. With AQPs present, water can "gush" through the membrane at the extraordinary rate of three billion water molecules per second per aquaporin channel. In their absence, water only trickles across the hydrophobic lipid bilayers of cell membranes. Aquaporins have fascinated researchers over the last decade, culminating in the 2003 Nobel Prize for Chemistry given to their discoverer, Dr. Peter Agre. During the 1990s, scientists identified and characterized members of the mammalian aquaporin family, now designated as AQP0 through AQP10. AQPs are also found in many plant and bacterial species. However, their relevance to the clinical laboratory is only recently emerging. Dr. Agre's Nobel symposium address provides an excellent mini-review of aquaporins in medicine. Our understanding of renal physiology and pathophysiology has advanced greatly as we account for the subtle implications of various AQP systems. For example, nephrogenic diabetes insipidus (NDI), the inability to produce concentrated urine, can result from several different malfunctions in the AQP2 system controlled by anti-diuretic hormone (ADH). Virtually all mammalian cells incorporate aquaporins into their cell membranes, and many cells produce multiple aquaporins, each with a specific function. It is therefore not surprising that malfunctions have important clinical conditions. The present article discusses the implications of aquaporins for renal physiology, while the accompanying article is focused on the clinical aspects of aquaporins.