Incidence, distribution, and morphology of amyloidosis in Charles Rivers CD-1 mice.

The incidence, morphology, and distribution of amyloidosis were reviewed in a 2-year toxicity-oncogenicity study in Charles Rivers CD-1 mice. Amyloid was present in the duodenum, jejunum, mesenteric lymph node, and ovary in animals sacrificed at 8 months. In animals sacrificed at 12 months, amyloid was also present in the adrenal gland, gall bladder, heart, ileum, kidney, pancreas, parathyroid, spleen, glandular stomach, testis, and thyroid. In the animals sacrificed at 24 months, the gland was also involved. The organs most frequently involved at 24 months included the adrenal gland, duodenum, jejunum, ileum, heart, kidney, liver, mesenteric lymph node, ovary, spleen, and thyroid.     

Aquaporin water channels in gastrointestinal physiology

Fluid transport is a major function of the gastrointestinal (GI) tract with more than 9 litres of fluid being absorbed or secreted across epithelia in human salivary gland, stomach, the hepatobiliary tract, pancreas, small intestine and colon. This review evaluates the evidence that aquaporin-type water channels are involved in GI fluid transport. The aquaporins are a family of small (≈30 kDa) integral membrane proteins that function as water channels. At least seven aquaporins are expressed in various tissues in the GI tract: AQP1 in intrahepatic cholangiocytes, AQP4 in gastric parietal cells, AQP3 and AQP4 in colonic surface epithelium, AQP5 in salivary gland, AQP7 in small intestine, AQP8 in liver, pancreas and colon, and AQP9 in liver. There are functional data suggesting that some GI cell types expressing aquaporins have high or regulated water permeability; however, there has been no direct evidence for a role of aquaporins in GI physiology. Recently, transgenic mice have been generated with selective deletions of various aquaporins. Preliminary evaluation of GI function suggests a role for AQP1 in dietary fat processing and AQP4 in colonic fluid absorption. Further study of aquaporin function in the GI tract should provide new insights into normal GI physiology and disease mechanisms, and may yield novel therapies to regulate fluid movement in GI diseases.     

Role of water channels in fluid transport studied by phenotype analysis of aquaporin knockout mice

Aquaporin-type water channels are expressed widely in mammalian tissues, particularly in the kidney, lung, eye and gastrointestinal tract. To define the role of aquaporins in organ physiology, we have generated and analysed transgenic mice lacking aquaporins (AQP) 1, 3, 4 and 5. Multiple phenotype abnormalities were found in the null mice. For example, in kidney, deletion of AQP1 or AQP3 produced marked polyuria whereas AQP4 deletion produced only a mild concentrating defect. Deletion of AQP5, the apical membrane water channel in the salivary gland, caused defective saliva production. Deletion of AQP1 or AQP5, water channels in lung endothelia and epithelia, resulted in a 90% decrease in airspace-capillary water permeability. In the brain, deletion of AQP4 conferred marked protection from brain swelling induced by acute water intoxication and ischaemic stroke. The general paradigm that has emerged from these phenotype studies is that aquaporins facilitate rapid near-isosmolar transepithelial fluid absorption/secretion, as well as rapid vectorial water movement driven by osmotic gradients. However, we have found many examples in which the tissue-specific expression of an aquaporin is not associated with any apparent phenotypic abnormality. The physiological data on aquaporin null mice suggest the utility of aquaporin blockers and aquaporin gene replacement in selected human diseases.     

Aquaporin 7 and aquaporin 8 expression in the testis of rat of different age and regulation conducted by panaxadiol saponins

Aquaporin 7 and aquaporin 8 expression in the testis of rat of different age and regulation conducted by panaxadiol saponins     

Aquaporins in the central nervous system

In this review, we have tried to summarize most available data dealing with the aquaporin (AQP) family of water channels in the CNS. Two aquaporins have been identified so far in the CNS, AQP1 and AQP4. AQP1 is restricted to the choroid plexus of the lateral ventricles, which raises a role for this aquaporin in cerebrospinal fluid formation. AQP4 is the predominant water channel in the brain and it is more widely distributed than originally believed, with a marked prevalence over periventricular areas. In the first part of this review, we examine the complete distribution pattern of AQP4 in the CNS including its rostro-caudal localization to end with its subcellular location. After discussing scarce data dealing with regulation of aquaporins in the CNS, we focus in potential roles for aquaporins. Novel recent data highlights very important roles for this aquaporin in the normal and pathological brain including, among others, role in potassium buffering, body fluid homeostasis, central osmoreception and development and restoration of brain edema.     

Expression of aquaporin3 in human neoplastic tissues

Niu D, Kondo T, Nakazawa T, Yamane T, Mochizuki K, Kawasaki T, Matsuzaki T, Takata K & Katoh R
(2012) Histopathology  61, 543–551 Expression of aquaporin3 in human neoplastic tissues Aims: Aquaporin3 (AQP3) is distributed widely in mammalian tissues and plays an important role in fluid homeostasis. The aim of this study was to investigate the pattern of expression of AQP3 in a variety of human neoplastic tissues and to explore its diagnostic implications. Methods and results: We studied 798 neoplastic tissues using immunohistochemistry with anti‐AQP3 antibody. We demonstrated a high positive frequency of AQP3 immunoreactivity in pituitary adenomas, salivary gland tumours, thymic tumours, adenocarcinoma of the lung and prostate, squamous cell carcinomas of the skin, oesophagus and uterine cervix, apocrine carcinoma of the breast, germinal cell tumours of the ovary and testis and urothelial carcinoma of the bladder. None of the sarcomas or central nervous system tumours showed AQP3 immunoreactivity. Most tumours with a high frequency of AQP3 positivity had corresponding or surrounding normal cells that also expressed AQP3. AQP3 was not a specific marker for benign or malignant epithelial neoplasms. Conclusion: AQP3 protein is expressed in a variety of epithelial tumours limiting its use as a diagnostic marker. Furthermore, AQP3 expression in tumour cells reflected the expression status of AQP3 in the corresponding normal cells. Our data suggest that water metabolism through AQP3 is maintained during neoplastic transformation in most human tissues.     

硝酸镧对大鼠睾丸7型水通道基因表达的影响

目的:观察不同剂量稀土元素-镧对大鼠睾丸7型水通道(aquaporin7,AQP7)基因表达水平的影响。方法:取硝酸镧灌胃6个月大鼠的睾丸组织提取总RNA进行Northernblot分析。结果:低剂量La(NO₃)₃(0.1mg/kg)抑制大鼠睾丸AQP7的mRNA表达,而高剂量La(NO₃)₃(20mg/kg)的作用与对照组比较无明显差别。结论:大鼠睾丸内可见AQP7mRNA的表达;硝酸镧能影响大鼠睾丸AQP7mRNA表达的强度。     

Aquaporins in the digestive system

Fluid transfer such as secretion and absorption is one of the major functions of the digestive system. Aquaporins are water channel proteins providing water transfer across the cellular membrane. At least six aquaporin isoforms are expressed in the digestive system. Aquaporin-1 (AQP1) is widely distributed in endothelial cells of capillaries and small vessels as well as in the central lacteals in the small intestine. AQP1 is also present in the duct system in the pancreas, liver, and bile duct. AQP3 is mainly expressed in the epithelia of the upper digestive tract from the oral cavity to the stomach and of the lower digestive tract from the distal colon to the anus. AQP4 is present in the parietal cells of the stomach and in the intestinal epithelia. AQP5 is expressed in acinar cells of the salivary, pyloric, and duodenal glands. AQP8 is expressed in the intestinal epithelia, salivary glands, pancreas, and liver. AQP9 is present in the liver and intestinal goblet cells. Aquaporins have important roles in the digestive system, such as AQP5 in saliva secretion, as shown by the studies on AQP5-null mice. In addition, water transfer across the digestive epithelia seems to occur not only via aquaporins but also via other transporter or channel systems.     

Lead induces increased water permeability in astrocytes expressing aquaporin 4

The water channel aquaporin 4 (AQP4) is abundantly expressed in astrocytes. There is now compelling evidence that AQP4 may contribute to an unfavorable course in brain edema. Acute lead intoxication is a condition that causes brain damage preceded by brain edema. Here we report that lead increases AQP4 water permeability (P(f)) in astrocytes. A rat astrocyte cell line that does not express aquaporin 4 was transiently transfected with aquaporin 4 tagged with green fluorescent protein (GFP). Using confocal laser scanning microscopy we measured water permeability in these cells and in AQP4-negative cells located on the same plate. AQP4-expressing astrocytes had a three-fold higher water permeability than astrocytes not expressing AQP4. Lead exposure induced a significant, 40%, increase in water permeability in astrocytes expressing AQP4, but had no effect on P(f) in astrocytes not expressing AQP4. The increase in water permeability persisted after lead washout, while treatment with a lead chelator, meso-2,3-dimercaptosuccinic acid, abolished the lead-induced increase in P(f). The effect of lead was attenuated in the presence of a calcium (Ca(2+))/calmodulin-dependent protein kinase II (CaMKII) inhibitor, but not in the presence of a protein kinase C inhibitor. In cells expressing AQP4 where the consensus site for CaMKII phosphorylation was mutated, lead failed to increase water permeability. Lead exposure also increased P(f) in rat astroglial cells in primary culture, which express endogenous AQP4. Lead had no effect on P(f) in astrocytes transfected with aquaporin 3. In situ hybridization studies on rat brain after oral lead intake for three days showed no change in distribution of AQP4 mRNA. It is suggested that lead-triggered stimulation of water transport in AQP4-expressing astrocytes may contribute to the pathology of acute lead intoxication.     

脑水通道蛋白的分布、功能及调控机制

背景：在哺乳动物脑中主要表达的水通道蛋白是水通道蛋白1、水通道蛋白4和水通道蛋白9,其他的仅为零星表达。目前国内外尚未见到系统分析维持脑正常生理功能的水通道蛋白分布、功能及其调节机制的综述报道。 目的：综述近年国内外维持脑正常生理功能的水通道蛋白分布、功能及其调节机制的研究进展。 方法：应用计算机检索1980年1月至2013年7月PubMed数据库、中国期刊全文数据库有关脑正常生理功能维持中水通道蛋白分布、功能及其调节机制的文章,英文检索词“AQP1, AQP4,AQP9, function, brain, adjusting mechanism”;中文检索词“水通道蛋白,功能,脑,调节机制”。共检索到163篇相关文献,85篇文献符合纳入标准。 结果与结论：近年来,有大量学者对脑水通道蛋白的表达、功能及其调节机制进行了较深层次的研究,具体归纳为如下3个方面：①水通道蛋白1主要表达于脑室脉络丛参与脑脊液的形成;在其他类型的细胞中,气体小分子CO2,NO,NH3 及O2也可通过水通道蛋白1。②水通道蛋白4主要表达在胶质细胞足突、胶质界膜以及室管膜中,帮助水进出脑组织,并加速胶质细胞迁移及改变神经活动。③水通道蛋白9主要分布于星形胶质细胞及儿茶酚胺等神经元中,主要功能是参与脑内能量代谢。水通道蛋白被认为是对脑中水运输提供关键路径的主要水通道,有关水通道蛋白分布、功能及调控机制的研究对于攻克脑相关疾病起重要作用。水通道蛋白在维持脑正常生理及相关疾病中表达的调节机制尚未明晰,相关分子信号通路尚待更加深入、系统地研究。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

水通道蛋白4在大鼠淋巴性脑水肿中的作用

 目的：研究水通道蛋白4（AQP4）在淋巴性脑水肿（LBE）形成和消散过程中的作用。方法：将大鼠随机分为假手术组和LBE组。采用结扎双侧颈部淋巴管并摘除淋巴结的方法,制作LBE模型。干湿重法检测大鼠大脑皮质含水量,应用免疫荧光组织化学方法及免疫印迹检测在颈淋巴引流阻滞后不同时点AQP4表达的变化情况,并对AQP4表达与脑含水量作相关分析。结果：与假手术组相比,LBE组大鼠脑含水量、AQP4免疫荧光表达阳性细胞数、强度及AQP4蛋白表达在术后3 d均见升高（P<0.05）,7 d升至高峰（P<0.01）,后逐渐降低,且AQP4蛋白表达与脑含水量呈正相关关系（r=0.8024,P<0.05）。结论：AQP4在大鼠LBE的形成和消散过程中起到了重要的作用。     

开胃素A在猪一些器官内的分布

目的：研究苏钟猪一些器官内开胃素(或增食因子)A(orexin A)的分布。方法：免疫组织化学法。结果：开胃素A免疫阳性细胞分布于猪睾丸、肾上腺、胰腺、小肠、甲状腺和胸腺等部位,睾丸间质、胰岛和小肠的粘膜固有层有大量免疫阳性细胞存在,而在肾上腺皮质、甲状腺和胸腺等部位仅有少量免疫阳性细胞分布。结论：猪一些器官内开胃素A的分布与人和其他动物的基本相似。首次报道了开胃素A在甲状腺和胸腺的分布,反映了开胃素在种系发生上的保守性,也说明存在种间差异。     

先天性白血病临床病理学分析（附6例尸检报告）

目的　探讨先天性白血病的病理临床特点 .方法　收集 6例死亡病例 ,进行尸检及临床分析 .结果　 6例检查中 ,肿瘤细胞广泛侵犯内脏器官 ,心、肝、脾、肺、肾和消化道的有 6例 ;骨髓、淋巴结、胸腺、胰、肾上腺有 5例 ;脑和甲状腺 4例 ;膀胱 3例 ;脑膜和皮肤 2例 ;舌咽、睾丸、子宫各 1例 .6例中急淋占 4例 ,急非淋 (急单 ) 2例 ;免疫分型 4例急淋全为T细胞性 ,表现为CD4 5RO( )、CD3( )表达 ;2例急非淋 ;1例CD6 8( )、Lyso( )表达 ,诊断为急单可能性大 (本例生后 1小时死亡 ,临床未及血液学检查、FAB分类 ) ;另 1例为早期病例 ,骨髓涂片FAB分型M5 ,未进行免疫检测分型 .结论　先天性白血病在尸检材料中见肿瘤细胞呈广泛性内脏器官浸润 ,并且血管腔内瘤栓形成 ,沿血道传播全身 .本病有发病早、病情急而凶险、治疗困难预后差、早期死亡的特点 .     

Natriuretic peptides up-regulate aquaporin 3 in a human colonic epithelial cell line

Several specialized channels termed aquaporins (AQPs) facilitate water transport in the gastrointestinal tract. AQP3 localizes to epithelial cells in the human small intestine and colon. However, the regulatory mechanisms responsible for AQP3 function in the gastrointestinal tract are not well understood. To characterize the regulation of AQP3 expression by atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), we studied mRNA expression by Northern blotting, protein expression by Western blotting and DNA binding activity by electrophoretic mobility shift assay (EMSA) in the human colonic epithelial cell line HT-29. We also used several inhibitors to investigate signal transduction. AQP3 mRNA was up-regulated in addition to ANP (>100 nM) and BNP (>10 nM). The expression of AQP3 protein was enhanced at 1 h after the addition of ANP and BNP. The combination of protein kinase-A (PK-A) and protein kinase-G (PK-G) inhibitors completely inhibited the expression of AQP3 mRNA enhanced by ANP or BNP to its basal level. The EMSA of the cyclic-AMP response element (CRE) in HT-29 cells revealed a single band. These results indicate that ANP and BNP up-regulated the expression of AQP3 mRNA and protein, and both PK-A and PK-G dependent pathways mediated this effect.     

Immunolocalization of aquaporin-9 in rat hepatocytes and Leydig cells

The aquaporin (AQP)-9 gene was recently isolated from human and rat liver cDNA libraries as a member of the water channel family for water and neutral solutes. Although the expression of AQP9 mRNA has been demonstrated in several organs including the liver and testis by Northern blot analysis, the cellular and subcellular localization of the AQP9 protein remains unclear. In the present light and electron microscopic immunohistochemical study, the localization of the AQP9 immunoreactivity was examined in fifteen kinds of rat organs using an antibody against rat AQP9 synthetic peptide. The antibody immunostained a major band of approximately 33 kDa in the liver by Western blot analysis. Immunoreactivity for AQP9 was found exclusively in the liver and testis among the organs examined. In the liver, positive staining appeared selectively along the space of Disse. Immunoelectron microscopy confirmed the localization of AQP9 on the surface of hepatocyte microvilli facing the space of Disse. In the testis, the plasma membrane of Leydig cells located between seminiferous tubules was conspicuously immunoreactive to the antibody. Intense mRNA expression was detected in the liver and testis but not in other organs by ribonuclease protection assay. These findings suggest a specific role for AQP9 in the transport of water and non-charged solutes in hepatocytes and Leydig cells.     

胶质瘤细胞对血脑屏障水通道表达的影响

目的:探索胶质瘤细胞对血脑屏障水通道表达的影响及其病理生理意义。方法:通过内皮细胞系与胶质细胞体外共培养的方法建立体外血脑屏障模型。利用重水及高效液相分析的方法观察胶质瘤细胞作用对血脑屏障水转运的影响。运用半定量RT-PCR的方法分析胶质瘤细胞作用后血脑屏障内皮细胞及胶质细胞水通道1和水通道4的表达变化。结果:胶质瘤细胞可以诱导血脑屏障内皮细胞水通道1的异常表达并降低胶质细胞水通道4的表达水平。同时,胶质瘤细胞明显增强了体外血脑屏障模型对水由内皮细胞腔面至基底面的扩散。结论:胶质瘤性脑水肿不一定是血浆等大分子物质通透性增加的结果。血脑屏障中水通道的表达变化是胶质瘤性脑水肿发生的重要分子机制。     

Role of human aquaporin 5 in colorectal carcinogenesis

While overexpression of several aquaporins (AQPs) has been reported in different types of human cancer, the role of AQPs in carcinogenesis has not been clearly defined. Here, by immunochemistry, we have found expression of AQP5 protein in 62.8% (59/94) of resected colon cancer tissue samples as well as association of AQP5 with liver metastasis. We then demonstrated that overexpression of human AQP5 (hAQP5) induces cell proliferation in colon cancer cells. Overexpression of wild-type hAQP5 increased proliferation and phosphorylation of extracellular signal-regulated kinase-1/2 in HCT116 colon cancer cells whereas these phenomena in hAQP5 mutants (N185D and S156A) were diminished, indicating that both membrane association and serine/threonine phosphorylation of AQP5 are required for proper function. Interestingly, overexpression of AQP1 and AQP3 showed no differences in extracellular signal-regulated kinase-1/2 phosphorylation, suggesting that AQP5, unlike AQP1, may be involved in signal transduction. Moreover, hAQP5-overexpressing cells showed an increase in retinoblastoma protein phosphorylation through the formation of a nuclear complex with cyclin D1 and CDK4. Small interfering RNA analysis confirmed that hAQP5 activates the Ras signaling pathway. These data not only describe the induction of hAQP5 expression during colorectal carcinogenesis but also provide a molecular mechanism for colon cancer development through the interaction of hAQP5 with the Ras/extracellular signal-regulated kinase/retinoblastoma protein signaling pathway, identifying hAQP5 as a novel therapeutic target.     

Lactic acid increases aquaporin 4 expression on the cell membrane of cultured rat astrocytes

The water channel protein aquaporin (AQP) may play roles in the homeostasis of water content in the brain and brain edema. One possible mechanism of brain edema is glial swelling due to lactic acidosis associated with ischemia. Here, we investigated the effect of lactic acid on the expression and cellular distribution of AQP 4 in cultured rat astrocytes. After 24h of incubation, the AQP4 expression level increased maximally with 35mM lactic acid. The AQP4 expression levels also increased with hydrochloric acid or acetic acid. In contrast, with sodium lactate, the AQP4 levels did not increase. The increase in AQP4 expression level occurred without a significant increase in AQP4 mRNA expression level by lactic acid. Under the conditions of de novo protein synthesis inhibition with cycloheximide, lactic acid increased the AQP4 expression level. Furthermore, lactic acid increased the AQP4 expression level on the cell surface of the astrocytes, as determined by a cell surface biotinylation assay and immunocytochemical examination. The increase in AQP4 expression level on the cell membrane of astrocytes induced by lactic acid may be a new regulation mechanism of AQP4 in the brain.     

Evidence that aquaporin-8 is located in the basolateral membrane of rat submandibular gland acinar cells

It is possible that, during primary saliva formation, aquaporins (AQPs) facilitate transcellular water flow across acinar cells to the lumina of salivary glands. In the rat submandibular gland (rSMG) AQP5 is localized in the apical membranes of acinar cells. The presence of a basolateral AQP in the same cell type has not been reported. We have therefore used immunofluorescence confocal microscopy to determine the subcellular localization of a newly discovered aquaporin, AQP8, in rSMG epithelial cells. The antibodies we used were made against the amino- or carboxyl-terminus (anti-rAQP8NT and anti-rAQP8CT, respectively) of an AQP8 cloned from rat pancreas and liver (rAQP8). Two lines of evidence suggest that both antibodies are suitable for immunolocalization studies. First, results of immunofluorescence confocal microscopy studies show that both antibodies bind to the plasma membranes of 293 cells infected with an adenovirus encoding rAQP8. Second, results of immunoblots of membranes from infected cells suggest that both antibodies bind to glycosylated and non-glycosylated forms of rAQP8. When tested in frozen sections of rSMG, we could not detect the binding of anti-rAQP8NT to any membranes. In contrast, anti-rAQP8CT binds to the basolateral membranes of acinar (but not ductal) epithelia, suggesting that rAQP8 resides in the basolateral membranes of acinar cells. Lack of anti-rAQPNT binding to basolateral membranes suggests that this epitope is not available in the membranes. Our evidence for the basolateral localization of rAQP8 in acinar cells, coupled with previous findings that AQP5 is localized apically in the same cells, raises the possibility that water crosses the acinar epithelium through these channels during primary saliva formation.     

Cellular localization of aquaporins along the secretory pathway of the lactating bovine mammary gland: An immunohistochemical study

In this study we examined the cellular localization of aquaporins (AQPs) along the secretory pathway of actively lactating bovine mammary glands using immunohistochemistry. Mammary tissues examined included secretory ducts and acini, gland cisterns, teats, stromal and adipose tissues. Aquaporin 1 (AQP1) was localized in capillary endothelia throughout the mammary gland in addition to myoepithelial cells underlying teat duct epithelia. AQP2 and AQP6 were not detected and AQP9 was found only in leukocytes. AQP3 and AQP4 were observed in selected epithelial cells in the teat, cistern and secretory tubuloalveoli. AQP5 immunopositivity was prominent in the cistern. AQP3 and AQP7 were found in smooth muscle bundles in the teat, secretory epithelial cells and duct epithelial cells. These immunohistochemical findings support a functional role for aquaporins in the transport of water and small solutes across endothelial and epithelial barriers in the mammary gland and in the production and secretion of milk.