Aquaporin-1 (AQP1) Antibody Review





  • The aquaporins (AQPs) are a family of water channel proteins with at least 13 mammalian members (AQPs 0-12) expressed in diverse fluid transporting tissues. PMID: 16534779

  • also known as CHIP, a channel-forming integral membrane protein of 28 kDa, is the first protein to be shown to function as a water channel. PMID: 12271491

  • a membrane channel that allows rapid water movement driven by a transmembrane osmotic gradient. PMID: 14701836

  • membrane proteins that control the permeability of endothelial and epithelial barriers by facilitating water movement across cell membranes. PMID: 15809704

  • a water channel protein expressed in vascular endothelia and involved in impaired angiogenesis in tumors. PMID: 17273788

  • a major pathway for CO2 transport across the human erythrocyte membrane. PMID: 17012249

  • a transmembrane water channel protein reportedly expressed in continuous capillary endothelium and intestinal lacteals. PMID: 15624322

  • a water channel expressed strongly at the ventricular-facing surface of choroid plexus epithelium. PMID: 15533949

  • plays a critical role for water reabsorption in the urinary concentrating mechanism. PMID: 15530434

  • a hexahelical integral membrane protein that functions as a regulated channel for water and cations in fluid-secreting and -absorbing tissues. PMID: 11431445

  • a water channel expressed abundantly at the apical pole of choroidal epithelial cells. PMID: 10710377

  • a member of the membrane intrinsic protein (MIP) gene family and is known to provide pathways for water flux across cell membranes, and have the capacity to participate in ionic signaling after the activation of cGMP second-messenger pathways. PMID: 10692499

Normal Expression

  • AQP1 and AQP4 are widely expressed in the central nervous system where they play several roles. PMID: 17868659

  • An AQP1 immunoreaction was recognizable in the axon terminals of the periodontal Ruffini endings as well as their associated terminal Schwann cells. Furthermore, the AQP1 immunoreaction was found in certain satellite cells which surrounded AQP1-positive or -negative neurons. PMID: 17553469

  • AQP1 is expressed at the endomysial capillary endothelial cell and further AQP1 may be expressed at the human skeletal myofiber plasma membrane. PMID: 17409744

  • Immunoblots of total protein identified a 28-kDa non-glycosylated AQP-1 band and a 56-kDa glycosylated AQP-1 band in the kidney and all four regions of the lower intestine. Immunohistochemistry demonstrated the presence of the AQP-1 protein within both the renal cortex and medulla. In the lower intestine, the protein was present in the proximal rectum, distal rectum, and in the coprodeum. PMID: 17320442

  • We detected the expression of AQP1 solely in endometrial blood vessels in the control group, as well as in menorrhagic endometrium. PMID: 17273788

  • 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. PMID: 17257750

  • AQP1 expresses mainly on the capillary endothelial cell of laryngeal mucous lamina propria, laryngeal mucous glands and myocyte nuclear membrane. PMID: 16646408

  • AQP1 water channel is specifically localized to glial cells of the peripheral nervous system by immunohistochemistry, RT-PCR, and immunoblotting. PMID: 16534779

  • In adult rat eye, AQP1 was localized to the apical and basolateral plasma membranes of iris epithelial cell layers and of anterior ciliary non-pigmented epithelial (NPE) cells. Developmentally, AQP1 was detected as early as E15 in immature iris and ciliary epithelial cells, and expression persisted throughout development up to adulthood. PMID: 16525835

  • Aquaporin-1 was expressed on the basilar part of spiral ligament, basal membrane of Corti's organ and epithelialis of scala tympani, and basilar part under the cellula epithelialis in endolymphatic sac. PMID: 16494013

  • The water channel, aquaporin (AQP) 1, was predominantly situated in the apical plasma membrane domain, although distinct basolateral and endothelial immunoreactivity was also observed. PMID: 16481371

  • photoreceptor cells, but not Müller cells, express aquaporin-1 in the murine retina. PMID: 16039047

  • AQP1 immunoreactivity was found in photoreceptor cells of the outer nuclear layer (ONL) and in a distinct type of amacrine cells of the inner nuclear layer (INL). PMID: 15952169

  • Intense, uniformly distributed AQP1 immunostaining was observable in the apical but not the basolateral side of cuboid cells of the choroid plexus (CP). PMID: 15821358

  • AQP1 was expressed in capillary endothelia of all normal tissues. PMID: 15809704

  • Rat intestine, mesentery, and lymph nodes were immunolabeled for AQ-1, revealing membrane expression in endothelial cells of vascular continuous capillaries and venules, and of initial and conducting lymphatics. PMID: 15624322

  • AQP1 has been identified in rodent heart and human heart. PMID: 15135660

  • Aquaporin-1 was found to be expressed in normal human cornea and decreased in human corneas with endothelial disease but not in human corneas with non-endothelial corneal disease. PMID: 14758337

  • AQP-1 was distributed on the membrane of lymphatic endothelium and reticular cells as well as on both luminal and abluminal cell membranes of high endothelial venules (HEVs). PMID: 14527167

  • AQP1 was first detected at embryonic day 10.5 (E10.5) in the otocyst but eventually localized to specific nonsensory portions of the inner ear and connective tissue cells surrounding the membranous labyrinth. PMID: 12943377

  • Eel AQP1 was expressed predominantly in the intestine, and the expression levels were higher in seawater eel than in freshwater eel. Immunocytochemical studies revealed intense AQP1 immunoreaction in the apical surface of columnar epithelial cells in seawater eel, in which the immunoreaction was stronger in the posterior intestine than in the anterior. PMID: 12939380

  • AQP1 protein was detected in human retinal pigment epithelial (RPE) in situ and in cultures of human adult and fetal RPE cells. PMID: 12766090

  • the AQP1 antibody labels a class of glycinergic amacrine cells with small to medium-sized dendritic fields in the rat retina. PMID: 12271491

  • Immunohistochemistry data demonstrate that AQP1 was clearly expressed in the ectodermal and endodermal epithelia, the vascular endothelium, and the vascular smooth muscle cells (VSMCs). PMID: 12221713

  • AQP-1 was localized to capillary and arteriole endothelial cells, whereas AQP-2 and -3 circumferentially lined the epithelial cell membranes except for the apical membrane of the epithelial cells adjacent to the lumens of both ureter and bladder. PMID: 11997319

  • AQP1 is present in endothelial cells in the lung, including those in the vascular plexus around the airways. PMID: 11773634

  • Immunohistochemical analysis showed that AQP1 was localized at capillary endothelial cells and fibroblasts in lamina propria mucosae; AQP4 was present solely at the basolateral membrane of ciliated cells, whereas AQP5 was on the apical surface of ciliated cells as well as of flat and columnar epithelial cells. PMID: 11506936

  • Aquaporin-1, (CHIP-28) is reported distributed in cardiac myocytes and vascular smooth muscle cells of large arteries. We report aquaporin expression in the cell membrane of smooth muscle cells of the rat genital tract; fluorescence immunohistochemistry of rat uterine (fallopian) tube and vagina demonstrated AQ-1 in visceral smooth muscle of these tissues. In the uterine tube, AQ-1 labelling is most pronounced in the innermost longitudinal and the inner cells of the circular muscle layer. PMID: 11286299

  • Immunocytochemistry showed expression of aquaporin-1 (AQP1) water channels at sites involved in dietary fat processing, including intrahepatic cholangiocytes, gallbladder, pancreatic microvascular endothelium, and intestinal lacteals. PMID: 11121384

  • Aquaporin-1 is expressed by vascular smooth muscle cells and mediates rapid water transport across vascular cell membranes. PMID: 10559675

  • cultured bovine corneal endothelial cells (CBCECs) reacted strongly with the anti-AQP1 antibody, and the labeling was selectively localized to the plasma membrane by light microscopy. Subcellular localization by EM revealed immunoreactivity with the inner leaflets of the plasma membrane. PMID: 10235568

  • Aquaporin 1 (AQP-1) is a water channel protein that is constitutively expressed in renal proximal tubule and descending thin limb cells as well as in endothelial cells of the descending vasa recta. AQP-1 was also expressed throughout the arterial portion of the renal vasculature of the fetal and neonatal kidney from gestational age 17 days to 1 wk after birth. AQP-1 immunoreactivity gradually disappeared from the renal vasculature between 1 and 2 wk of age and remained only in the descending vasa recta. PMID: 10198408

  • AQP-1 was immunoexpressed intensely in the apical brush border of the epithelium lining the efferent ducts at all ages studied, from late fetal life through puberty to adulthood. In the marmoset, but not the rat, AQP-1 was also expressed in the epithelium of the rete testis. PMID: 9724049

  • AQP-1 is very specifically located in capillary and venule endothelium but not in small-size arteries. PMID: 9688919

  • The AQP1-like immunoreactivity was present in a certain population of amacrine cells and in the proximal processes of Müller cells. Thus, AQP1 appears to be important in the retinal homeostasis. PMID: 9578142

Abnormal Expression

  • By immunohistochemistry, astrocytes with highly branched processes surrounding blood vessels, along with glial scar, expressed intensely AQP1 and AQP4 in MS and ischemic brain lesions. PMID: 17645239

  • The expression of AQP1 was increased in laryngeal carcinoma tissues over normal laryngeal tissues. PMID: 17511167

  • Significant upregulation of AQP1 expression was found in hemangioblastomas compared with control brain (P=0.002). In hemangioblastomas, expression of AQP1 was predominantly localized on membranes of stromal cells. PMID: 17077939

  • AQP1, AQP4, and VEGF were co-expressed in GFAP-positive astrocytes. AQP1 and AQP4 were expressed strongly in astrocytic end-feet in brain edema tissue. PMID: 16671493

  • The expressions of AQP1 and AQP5 decreased in hyperoxia-induced lung injury and correlated with the severity of pulmonary edema. PMID: 16613712

  • AQP1 was overexpressed in 62% (13 of 21) and 75% (6 of 8) of adenocarcinoma and bronchoalveolar carcinoma, respectively, whereas all cases of squamous cell carcinoma and normal lung tissue were negative. PMID: 16565507

  • AQP1 has been found to be expressed in fibroblasts located in polyp tissue, especially in the subepithelial area, periphery of seromucous glands, and endothelial cells of venules. PMID: 16539309

  • AQP1 was located mainly in microvessels and small vessels but seldom in tumor cells. Expression of AQP1 and IMD in ovarian malignant tumors was significantly higher than that in borderline tumors (P= 0.000, P= 0.001, respectively), and that in borderline tumors was higher than in benign tumors (P= 0.008, P= 0.028, respectively). PMID: 16515633

  • Stromal cancer cells showed surprisingly high AQP1 expression, and huge cyst volume development showed correlation with higher immunostaining scores. PMID: 16300893

  • In most tumors AQP1 was confined to endothelial barriers. AQP1 expression was marginally higher in microvascular structures in prostate and ovarian tumors and was higher in advanced mammary and colorectal carcinomas where AQP1 immunoreactivity was also seen in some neoplastic tumor cells. In conclusion, the AQP1 water channel is an excellent marker of microvasculature but it is heterogeneously expressed in different human tumors and not necessarily expressed in all neoplastic cells. PMID: 15809704

  • AQP1, normally restricted to choroid epithelia, was highly expressed in glioblastomas. PMID: 15670385

  • This is the first report showing AQP-1 cell expression in adolescent varicocele testes in both tubular and extratubular compartments. PMID: 15667881

  • AQP-1 is located not only in the endothelial cell layer of capillaries and small vessels in the peritoneum of peritoneal dialysis (PD) patients, but also in the mesothelial cell layer. PMID: 15211447

  • Immunohistochemical localization of AQP(1) in mice tumor was labeled in capillaries, post capillary venules endothelial cells. PMID: 15169637

  • Aquaporin-1 (AQP1) expression was evaluated via Western blot and immunohistochemistry. Intense upregulation of AQP1 expression was found in all glioblastomas. PMID: 14753494

  • In astrocytomas, aquaporin 1 was expressed in microvessel endothelia and neoplastic astrocytes. In metastatic carcinomas, aquaporin 1 was present in microvessel endothelia and reactive astrocytes. PMID: 12237771

  • AQP1 was found in human peritoneal endothelial cells and human peritoneal mesothelial cells (HPMC) in both control subjects and patients on peritoneal dialysis. PMID: 11316863

  • AQP1 water channel is heterogeneously expressed in tumor cells and their vasculature, and that the level of expression is determined not only by the specific cellular origin of the tumor, but also by the location of the tumor in the host animal. PMID: 10458924


  • lung AQP-1 is markedly up-regulated in animals exposed to hypoxia. These data suggest that AQP-1 has O2 permeability and thus could facilitate O2 diffusion across the cell membrane. PMID: 17673462

  • Aquaporin-1 (AQP1) is the principal water-transporting protein in cell plasma membranes in kidney proximal tubule, where it facilitates transepithelial water transport and also involving the migration of proximal tubule cells. PMID: 16319186

  • AQP1-IR neurons probably play a significant role within the ENS to control gut functions. PMID: 16309835

  • AQP-1 contributes to the survival of eosinophils in nasal polyps by keeping the permeation balance of eosinophils. PMID: 15563082

  • Aquaporin-1 (AQP1) has been reported to play an important role in water permeability in peritoneal dialysis. PMID: 15384792

  • AQP1 plays an important role in the physiological accommodation to fetal anaemia. PMID: 14603367

  • AQP1 clearly serves to increase CO2 permeation, likely through the water pore; under certain circumstances, gas permeation through membranes is protein-mediated. PMID: 9837877

Diagnostic & Therapeutic Value

  • AQP-1 seems to be a highly selective marker for differentiated cholangiocytes and can be very helpful in the differential diagnosis of liver tumors. PMID: 16260277



Immunoblot (IB)

  • AQP1 expression in the third ventricle choroid plexus epithelium was determined by using immunohistochemistry and quantitative immunoblot analysis. PMID: 16293370

  • A band of 28 kD in agreement with the molecular size of aquaporin-1 was showed in a film by immunoblotting. PMID: 15510673

  • Immunoblot analysis showed that bone marrow biopsies of patients with active multiple myeloma (MM) display significantly higher levels of AQP1 than those from patients with non-active MM, whose values are higher, but to a lesser extent, than those of patients with monoclonal gammopathies of undetermined significance (MGUS). PMID: 11380407

  • Immunoblotting and immunohistochemical studies demonstrated significantly reduced levels of AQP1 and AQP5 protein after infection as well. PMID: 10615063

  • AQP1 was quantitated by immunoblotting in apical and basolateral plasma membranes prepared from cholangiocytes isolated from rats 20 min after intravenous infusion of secretin. PMID: 9887005

  • Immunoblotting of these fractions showed that the transmembrane water channel protein aquaporin-1 was amply expressed on the endothelial cell surface at levels comparable to rat erythrocyte plasma membranes. PMID: 8769778

Immuno-Electron Microscopy (IEM)

  • The ultrastructural localization of AQP1 in the mouse inner ear was performed by immunogold electron microscopy which is characterized as cryoprotection and high sensitivity. PMID: 17633275

  • Using real-time reverse transcriptase-polymerase chain reaction and immunogold electron microscopy, we showed that AQP1 is the most abundant member of the AQP gene family expressed in the mouse peritoneum, and the only one located in the capillary endothelium. PMID: 16508653

  • Immunolocalization at the electron microscope level indicated that AQP1 was localized to the plasma membrane of smooth muscle cells found within the inner circular layer. It is suggested that AQP1 plays a role in stromal oedema, uterine closure and orientation of the blastocyst. PMID: 15323352

  • we performed light- and electron-microscopic (EM) immunohistochemistry for AQP1 in the rat pancreatic ducts. PMID: 12012207

  • The pattern of aquaporin-1 water channel protein (AQP1) expression in the human kidney was analyzed by immunocytochemistry using semi-thin and optimized high-resolution immunoelectron microscopy based on freeze-substituted and Lowicryl HM20 embedded tissue. PMID: 9013443

  • Immunoelectron microscopy revealed AQP1 on both apical and basolateral membranes of endothelial cells. PMID: 8636397

Immunocytochemistry (ICC)

  • The presence of AQP1 was determined immunocytochemically in five different mammalian species (rat, mouse, human, sheep and opossum) in all four choroid plexuses from their earliest appearance. PMID: 16133142

  • For immunocytochemistry, cultured bovine corneal endothelial cells (CBCEC) and bovine corneal cryosections were utilized. Preparations were fixed, permeabilized, and incubated with primary rabbit anti-rat aquaporin 1 (AQP1) antibody followed by rhodamine-conjugated secondary antibody, and were counter-stained with Sytox nuclear acid stain. PMID: 11393176

Immunofluorescence (IF)

  • The expression and localization of water AQP1 were examined by Western blotting, RT-PCR, and immunofluorescence. PMID: 15265288

  • Indirect immunofluorescence microscopy with affinity purified antibodies against a fusion protein containing the carboxy tail of aquaporin-1 showed specific labeling of the plasma membrane and immunoblotting identified a band of Mr 28,000 which agrees with the molecular size of aquaporin-1. PMID: 8974838

Immunohistochemistry (IHC)

  • we determined AQP-1 expression in the normal bile duct, 21 cases of biliary dysplasia, and in 112 cases of intrahepatic cholangiocarcinoma by immunohistochemical analysis. PMID: 17854859

  • Immunohistochemistry and western blot were used to examine the expression of AQP1 in cochlea and endolymphatic sac of animal models. Image processing soft (Image Tool) was used to do the semiquantitative analysis. PMID: 17633274

  • This immunohistochemical study describes the developmental expression pattern of the water channel membrane proteins, aquaporin-1 and aquaporin-4, in various structures of human fetal brain over the gestational period of 14-40 weeks. PMID: 16814974

  • Immunohistochemical technique-supervision method was employed to measure, and image analysis system to analyze the expression of AQP-1 in normal cultured bovine trabecular meshwork cells and those treated with dexamethasone. PMID: 16696342

  • The distribution and protein expressions of AQP-1 on the rats' peritonea were measured with immunohistochemistry assay. PMID: 16029543

  • AQP-1 expression was detected by means of immunohistochemistry and a semiquantitative scoring system. PMID: 15211447

  • Immunohistology using AQP 1 and C-kit antibodies was performed on paraffin sections of open-testicular biopsies from 32 undescended testes. AQP 1 antibody strongly depicted microvessel endothelial cells, but was unlabeled in endotubular and interstitial cell lines, in both control and undescended testes. PMID: 15133700

  • We investigated the expression of aquaporin-1 (AQP1) in the rat inner ear using reverse transcription polymerase chain reaction and immunohistochemical methods. PMID: 12855358

  • An immunohistochemical analysis of AQP-1 and AQP-9 was undertaken to describe their expression in fetal and adult pig liver. PMID: 12835575

  • Immunohistochemistry of rat peritoneal tissues showed the presence of AQP1 in mesothelial cells, venular endothelial cells, and capillary endothelial cells, but not in arteriole and interstitial cells. PMID: 12227387

  • The species-specific difference of the immunohistochemical localization of aquaporin-1 (AQP1) and aquaporin-4 (AQP4) was investigated in the cochleae of the 3 different species of rodents, including guinea pig, mouse and Mongolian gerbil. PMID: 12086153

Immunoprecipitation (IP)

  • To determine whether AQP1 is ubiquitinated, immunoprecipitation with anti-AQP1 antibodies was performed, and the resultant samples were probed by protein immunoblot for the presence of ubiquitin. PMID: 11226337

Western Blot (WB)

  • The present study examines, by gel electrophoresis and Western blotting, the expression levels of the water channels aquaporin 1 (AQP1) and aquaporin 4 (AQP4) in the frontal cortex (area 8) homogenates of sporadic CJD cases. PMID: 16871401

  • deoxyribonucleic acid array, Western blot analysis, and immunohistochemical analysis revealed intense up-regulation of AQP1 expression in all glioblastomas studied. PMID: 15670385

  • AQP1 Western blot were performed in a murine model of lipopolysaccharide-induced acute lung injury. PMID: 15351300

  • We analyzed the change in expression of inducible NOS (iNOS), neuronal NOS (nNOS), endothelial NOS (eNOS), aquaporin 1 (AQP1) and aquaporin 5 (AQP5) over time by Western blot. PMID: 14767587

  • The purpose of this study was to investigate the expression of AQP1 and AQP4 in human brain after subarachnoid hemorrhage (SAH) and in peritumoral tissue by western blot and immunohistochemistry. The results showed a marked increase of the expression of AQP1 and AQP4. PMID: 14753493

  • Western blot, immuno-histochemical staining and reverse transcript-polymerase chain reaction (RT-PCR) techniques were used to investigate AQP1 expression. PMID: 14527368

  • Western analysis and immunocytochemistry were used to examine the expression of aquaporin 1 (AQP1) and aquaporin 4 (AQP4) in the rat choroid plexus epithelium. PMID: 12507761

  • Western analysis, and immunohistochemistry were used to determine expression and localization of AQP1 and AQP3. PMID: 12388974

  • Western blot analysis revealed 28 kDa and 35 kDa bands corresponding to unglycosylated and glycosylated AQP1 proteins in human glomeruli. Immunoreactive AQP1 was demonstrated almost exclusively in the mesangium in the human glomeruli by immunohistochemistry. The endothelium of glomerular capillaries was only partly immunostained while podocytes and Bowman's capsule epithelia were not immunolabeled. Immunoelectron microscopy localized the immunoreactive AQP1 on the plasma membrane of mesangial cells in human glomeruli. The immouno-gold labeling was dense on the projections of mesangial cells protruding to the glomerular capillary lumen or to endothelial cells, but was sparse on other parts of the mesangial cell surface. PMID: 12002613