Science.gov

Sample records for aqp4 aqp5 amtb

  1. Neuroimmunological Implications of AQP4 in Astrocytes

    PubMed Central

    Ikeshima-Kataoka, Hiroko

    2016-01-01

    The brain has high-order functions and is composed of several kinds of cells, such as neurons and glial cells. It is becoming clear that many kinds of neurodegenerative diseases are more-or-less influenced by astrocytes, which are a type of glial cell. Aquaporin-4 (AQP4), a membrane-bound protein that regulates water permeability is a member of the aquaporin family of water channel proteins that is expressed in the endfeet of astrocytes in the central nervous system (CNS). Recently, AQP4 has been shown to function, not only as a water channel protein, but also as an adhesion molecule that is involved in cell migration and neuroexcitation, synaptic plasticity, and learning/memory through mechanisms involved in long-term potentiation or long-term depression. The most extensively examined role of AQP4 is its ability to act as a neuroimmunological inducer. Previously, we showed that AQP4 plays an important role in neuroimmunological functions in injured mouse brain in concert with the proinflammatory inducer osteopontin (OPN). The aim of this review is to summarize the functional implication of AQP4, focusing especially on its neuroimmunological roles. This review is a good opportunity to compile recent knowledge and could contribute to the therapeutic treatment of autoimmune diseases through strategies targeting AQP4. Finally, the author would like to hypothesize on AQP4’s role in interaction between reactive astrocytes and reactive microglial cells, which might occur in neurodegenerative diseases. Furthermore, a therapeutic strategy for AQP4-related neurodegenerative diseases is proposed. PMID:27517922

  2. Deletional tolerance prevents AQP4-directed autoimmunity in mice

    PubMed Central

    Vogel, Anna-Lena; Knier, Benjamin; Lammens, Katja; Kalluri, Sudhakar Reddy; Kuhlmann, Tanja; Bennett, Jeffrey L.; Korn, Thomas

    2017-01-01

    Neuromyelitis optica (NMO) is an autoimmune disorder of the central nervous system (CNS) mediated by antibodies to the water channel protein AQP4 expressed in astrocytes. The contribution of AQP4-specific T cells to the class switch recombination of pathogenic AQP4-specific antibodies and the inflammation of the blood–brain barrier is incompletely understood, as immunogenic naturally processed T-cell epitopes of AQP4 are unknown. By immunizing Aqp4−/− mice with full-length murine AQP4 protein followed by recall with overlapping peptides, we here identify AQP4(201-220) as the major immunogenic IAb-restricted epitope of AQP4. We show that WT mice do not harbor AQP4(201–220)-specific T-cell clones in their natural repertoire due to deletional tolerance. However, immunization with AQP4(201–220) of Rag1−/− mice reconstituted with the mature T-cell repertoire of Aqp4−/− mice elicits an encephalomyelitic syndrome. Similarly to the T-cell repertoire, the B-cell repertoire of WT mice is “purged” of AQP4-specific B cells, and robust serum responses to AQP4 are only mounted in Aqp4−/− mice. While AQP4 (201–220)-specific T cells alone induce encephalomyelitis, NMO-specific lesional patterns in the CNS and the retina only occur in the additional presence of anti-AQP4 antibodies. Thus, failure of deletional T-cell and B-cell tolerance against AQP4 is a prerequisite for clinically manifest NMO. PMID:28058717

  3. Upregulation of AQP3 and AQP5 induced by dexamethasone and ambroxol in A549 cells.

    PubMed

    Ben, Yong; Chen, Jie; Zhu, Rong; Gao, Lei; Bai, Chunxue

    2008-04-30

    Aquaporins (AQPs) are membrane channel proteins that play roles in the regulation of water permeability in many tissues. AQP1 and AQP5 expressed in lung provide the principal route for osmotically driven water transport. In the airways, AQP3 and AQP4 facilitate water transport. Dexamethasone and ambroxol are often used to treat patients with pulmonary diseases accompanied by airway hypersecretion. The role of AQPs in these effective treatments has not been addressed. In this study, we analyzed the expression of AQPs in a human airway epithelial cell line (A549 cells) and showed that AQP3 and 5, but not AQP1 and 4, were expressed in A549 cells. Both dexamethasone and ambroxol stimulated the expression of AQP3 and 5 at the mRNA and protein levels. The data suggest potential roles of AQP3 and 5 in the regulation of airway hypersecretion, perhaps ultimately providing a target for treating such diseases.

  4. FREEZE-FRACTURE AND IMMUNOGOLD ANALYSIS OF AQUAPORIN-4 (AQP4) SQUARE ARRAYS, WITH MODELS OF AQP4 LATTICE ASSEMBLY

    PubMed Central

    RASH, J. E.; DAVIDSON, K. G. V.; YASUMURA, T.; FURMAN, C. S.

    2007-01-01

    Each day, approximately 0.5–0.9 l of water diffuses through (primarily) aquaporin-1 (AQP1) channels in the human choroid plexus, into the cerebrospinal fluid of the brain ventricles and spinal cord central canal, through the ependymal cell lining, and into the parenchyma of the CNS. Additional water is also derived from metabolism of glucose within the CNS parenchyma. To maintain osmotic homeostasis, an equivalent amount of water exits the CNS parenchyma by diffusion into interstitial capillaries and into the subarachnoid space that surrounds the brain and spinal cord. Most of that efflux is through AQP4 water channels concentrated in astrocyte endfeet that surround capillaries and form the glia limitans. This report extends the ultrastructural and immunocytochemical characterizations of the crystalline aggregates of intramembrane proteins that comprise the AQP4 “square arrays” of astrocyte and ependymocyte plasma membranes. We elaborate on recent demonstrations in Chinese hamster ovary cells of the effects on AQP4 array assembly resulting from separate vs. combined expression of M1 and M23 AQP4, which are two alternatively spliced variants of the AQP4 gene. Using improved shadowing methods, we demonstrate sub-molecular cross-bridges that link the constituent intramembrane particles (IMPs) into regular square lattices of AQP4 arrays. We show that the AQP4 core particle is 4.5 nm in diameter, which appears to be too small to accommodate four monomeric proteins in a tetrameric IMP. Several structural models are considered that incorporate freeze-fracture data for submolecular “cross-bridges” linking IMPs into the classical square lattices that characterize, in particular, naturally occurring AQP4. PMID:15561408

  5. Protective role of brain water channel AQP4 in murine cerebral malaria

    PubMed Central

    Promeneur, Dominique; Lunde, Lisa Kristina; Amiry-Moghaddam, Mahmood; Agre, Peter

    2013-01-01

    Tragically common among children in sub-Saharan Africa, cerebral malaria is characterized by rapid progression to coma and death. In this study, we used a model of cerebral malaria appearing in C57BL/6 WT mice after infection with the rodent malaria parasite Plasmodium berghei ANKA. Expression and cellular localization of the brain water channel aquaporin-4 (AQP4) was investigated during the neurological syndrome. Semiquantitative real-time PCR comparing uninfected and infected mice showed a reduction of brain AQP4 transcript in cerebral malaria, and immunoblots revealed reduction of brain AQP4 protein. Reduction of brain AQP4 protein was confirmed in cerebral malaria by quantitative immunogold EM; however, polarized distribution of AQP4 at the perivascular and subpial astrocyte membranes was not altered. To further examine the role of AQP4 in cerebral malaria, WT mice and littermates genetically deficient in AQP4 were infected with P. berghei. Upon development of cerebral malaria, WT and AQP4-null mice exhibited similar increases in width of perivascular astroglial end-feet in brain. Nevertheless, the AQP4-null mice exhibited more severe signs of cerebral malaria with greater brain edema, although disruption of the blood–brain barrier was similar in both groups. In longitudinal studies, cerebral malaria appeared nearly 1 d earlier in the AQP4-null mice, and reduced survival was noted when chloroquine rescue was attempted. We conclude that the water channel AQP4 confers partial protection against cerebral malaria. PMID:23277579

  6. Protective role of brain water channel AQP4 in murine cerebral malaria.

    PubMed

    Promeneur, Dominique; Lunde, Lisa Kristina; Amiry-Moghaddam, Mahmood; Agre, Peter

    2013-01-15

    Tragically common among children in sub-Saharan Africa, cerebral malaria is characterized by rapid progression to coma and death. In this study, we used a model of cerebral malaria appearing in C57BL/6 WT mice after infection with the rodent malaria parasite Plasmodium berghei ANKA. Expression and cellular localization of the brain water channel aquaporin-4 (AQP4) was investigated during the neurological syndrome. Semiquantitative real-time PCR comparing uninfected and infected mice showed a reduction of brain AQP4 transcript in cerebral malaria, and immunoblots revealed reduction of brain AQP4 protein. Reduction of brain AQP4 protein was confirmed in cerebral malaria by quantitative immunogold EM; however, polarized distribution of AQP4 at the perivascular and subpial astrocyte membranes was not altered. To further examine the role of AQP4 in cerebral malaria, WT mice and littermates genetically deficient in AQP4 were infected with P. berghei. Upon development of cerebral malaria, WT and AQP4-null mice exhibited similar increases in width of perivascular astroglial end-feet in brain. Nevertheless, the AQP4-null mice exhibited more severe signs of cerebral malaria with greater brain edema, although disruption of the blood-brain barrier was similar in both groups. In longitudinal studies, cerebral malaria appeared nearly 1 d earlier in the AQP4-null mice, and reduced survival was noted when chloroquine rescue was attempted. We conclude that the water channel AQP4 confers partial protection against cerebral malaria.

  7. AQP4-Dependent Water Transport Plays a Functional Role in Exercise-Induced Skeletal Muscle Adaptations

    PubMed Central

    Basco, Davide; Blaauw, Bert; Pisani, Francesco; Sparaneo, Angelo; Nicchia, Grazia Paola; Mola, Maria Grazia; Reggiani, Carlo; Svelto, Maria; Frigeri, Antonio

    2013-01-01

    In this study we assess the functional role of Aquaporin-4 (AQP4) in the skeletal muscle by analyzing whether physical activity modulates AQP4 expression and whether the absence of AQP4 has an effect on osmotic behavior, muscle contractile properties, and physical activity. To this purpose, rats and mice were trained on the treadmill for 10 (D10) and 30 (D30) days and tested with exercise to exhaustion, and muscles were used for immunoblotting, RT-PCR, and fiber-type distribution analysis. Taking advantage of the AQP4 KO murine model, functional analysis of AQP4 was performed on dissected muscle fibers and sarcolemma vesicles. Moreover, WT and AQP4 KO mice were subjected to both voluntary and forced activity. Rat fast-twitch muscles showed a twofold increase in AQP4 protein in D10 and D30 rats compared to sedentary rats. Such increase positively correlated with the animal performance, since highest level of AQP4 protein was found in high runner rats. Interestingly, no shift in muscle fiber composition nor an increase in AQP4-positive fibers was found. Furthermore, no changes in AQP4 mRNA after exercise were detected, suggesting that post-translational events are likely to be responsible for AQP4 modulation. Experiments performed on AQP4 KO mice revealed a strong impairment in osmotic responses as well as in forced and voluntary activities compared to WT mice, even though force development amplitude and contractile properties were unvaried. Our findings definitively demonstrate the physiological role of AQP4 in supporting muscle contractile activity and metabolic changes that occur in fast-twitch skeletal muscle during prolonged exercise. PMID:23520529

  8. AQP4-dependent water transport plays a functional role in exercise-induced skeletal muscle adaptations.

    PubMed

    Basco, Davide; Blaauw, Bert; Pisani, Francesco; Sparaneo, Angelo; Nicchia, Grazia Paola; Mola, Maria Grazia; Reggiani, Carlo; Svelto, Maria; Frigeri, Antonio

    2013-01-01

    In this study we assess the functional role of Aquaporin-4 (AQP4) in the skeletal muscle by analyzing whether physical activity modulates AQP4 expression and whether the absence of AQP4 has an effect on osmotic behavior, muscle contractile properties, and physical activity. To this purpose, rats and mice were trained on the treadmill for 10 (D10) and 30 (D30) days and tested with exercise to exhaustion, and muscles were used for immunoblotting, RT-PCR, and fiber-type distribution analysis. Taking advantage of the AQP4 KO murine model, functional analysis of AQP4 was performed on dissected muscle fibers and sarcolemma vesicles. Moreover, WT and AQP4 KO mice were subjected to both voluntary and forced activity. Rat fast-twitch muscles showed a twofold increase in AQP4 protein in D10 and D30 rats compared to sedentary rats. Such increase positively correlated with the animal performance, since highest level of AQP4 protein was found in high runner rats. Interestingly, no shift in muscle fiber composition nor an increase in AQP4-positive fibers was found. Furthermore, no changes in AQP4 mRNA after exercise were detected, suggesting that post-translational events are likely to be responsible for AQP4 modulation. Experiments performed on AQP4 KO mice revealed a strong impairment in osmotic responses as well as in forced and voluntary activities compared to WT mice, even though force development amplitude and contractile properties were unvaried. Our findings definitively demonstrate the physiological role of AQP4 in supporting muscle contractile activity and metabolic changes that occur in fast-twitch skeletal muscle during prolonged exercise.

  9. AQP5 is differentially regulated in astrocytes during metabolic and traumatic injuries.

    PubMed

    Chai, Rui Chao; Jiang, Jiao Hua; Wong, Ann Yuen Kwan; Jiang, Feng; Gao, Kai; Vatcher, Greg; Hoi Yu, Albert Cheung

    2013-10-01

    Water movement plays vital roles in both physiological and pathological conditions in the brain. Astrocytes are responsible for regulating this water movement and are the major contributors to brain edema in pathological conditions. Aquaporins (AQPs) in astrocytes play critical roles in the regulation of water movement in the brain. AQP1, 3, 4, 5, 8, and 9 have been reported in the brain. Compared with AQP1, 4, and 9, AQP3, 5, and 8 are less studied. Among the lesser known AQPs, AQP5, which has multiple functions identified outside the central nervous system, is also indicated to be involved in hypoxia injury in astrocytes. In our study, AQP5 expression could be detected both in primary cultures of astrocytes and neurons, and AQP5 expression in astrocytes was confirmed in 1- to 4-week old primary cultures of astrocytes. AQP5 was localized on the cytoplasmic membrane and in the cytoplasm of astrocytes. AQP5 expression was downregulated during ischemia treatment and upregulated after scratch-wound injury, which was also confirmed in a middle cerebral artery occlusion model and a stab-wound injury model in vivo. The AQP5 increased after scratch injury was polarized to the migrating processes and cytoplasmic membrane of astrocytes in the leading edge of the scratch-wound, and AQP5 over-expression facilitated astrocyte process elongation after scratch injury. Taken together, these results indicate that AQP5 might be an important water channel in astrocytes that is differentially expressed during various brain injuries.

  10. No association of AQP4 polymorphisms with neuromyelitis optica and multiple sclerosis

    PubMed Central

    Ao, Dong-Hui; Wang, Yang-Yang; Zhang, Qi; He, Xiang-Jun; Zhong, Shan-Shan; Wu, Jian

    2016-01-01

    Abstract Multiple sclerosis (MS) and neuromyelitis optica (NMO) are inflammatory demyelinating disorders of the central nervous system (CNS). Various genetic and environmental factors have been identified to contribute to etiology of MS and NMO. Aquaporin 4 (AQP4), is the most abundant water channel in CNS. AQP4 is expressed in astrocytes of the brain, spinal cord, optic nerve and supportive cells in sensory organs. In contrast to MS, immunoreactivity of AQP4 is abolished in NMO lesions. However, conflicting results have been reported regarding the association between AQP4 polymorphisms and demyelinating disorders. Considering the ethnic differences of genetic variations, replications in other cohorts are required. In this study, single nucleotide polymorphisms (SNPs) of AQP4 gene in patients with NMO/neuromyelitis optica spectrum disorders (NMOSD), and MS in the Northern Han Chinese population were examined. Six selected AQP4 SNPs were genotyped by high-resolution melting (HRM) method. Compared with healthy control (HC), there was no significant difference of AQP4 allele and genotype frequency in MS or NMO/NMOSD group. This study showed no significant association of common AQP4 SNPs with MS or NMO/NMOSD, strongly suggesting that polymorphisms of AQP4 gene are unlikely to confer MS or NMO/NMOSD susceptibility, at least in Northern Han Chinese population. PMID:28123825

  11. Aquaporin-4 Autoantibodies in Neuromyelitis Optica: AQP4 Isoform-Dependent Sensitivity and Specificity

    PubMed Central

    Pisani, Francesco; Sparaneo, Angelo; Tortorella, Carla; Ruggieri, Maddalena; Trojano, Maria; Mola, Maria Grazia; Nicchia, Grazia Paola; Frigeri, Antonio; Svelto, Maria

    2013-01-01

    Neuromyelitis Optica (NMO) is an autoimmune demyelinating disease, characterized by the presence of autoantibody (NMO-IgG) to Aquaporin-4 (AQP4). NMO-IgG identification supports NMO diagnosis and several diagnostic tests have been developed, but their sensitivity is too variable, and some assay show low sensitivity. This impairs correct diagnosis of NMO. By cell based assay (CBA) we here evaluate the efficacy of different strategies to express AQP4 in mammalian cells in terms of: a) AQP4 translation initiation signals; b) AQP4 isoforms (M1 and M23) and fluorescent tag position; c) NMO serum concentration and AQP4 degradation. Our results demonstrate that when using AQP4-M1, the nucleotide in position −3 of the AUG greatly affects the AQP4-M1/M23 protein ratio, NMO-IgG binding, and consequently test sensitivity. Test sensitivity was highest with M23 expressing cells (97.5%) and only 27.5% with AQP4-M1. The fluorescent tag added to the N-terminus of AQP4-M23 considerably affected the NMO-IgG binding, and test sensitivity, due to disruption of AQP4 suprastructures. Furthermore, sera used at high concentration resulted in AQP4 degradation which affected test sensitivity. To further evaluate the reliability of the M23 based CBA test, samples of one NMO patient collected during about 2 years clinical follow-up were tested. The results of serum titer correlated with disease activity and treatment response. In conclusion, we provide a molecular explanation for the contrasting CBA test data reported and suggest the use of M23 with a C-terminus fluorescent tag as the proper test for NMO diagnosis. PMID:24260168

  12. Aquaporin-4 autoantibodies in Neuromyelitis Optica: AQP4 isoform-dependent sensitivity and specificity.

    PubMed

    Pisani, Francesco; Sparaneo, Angelo; Tortorella, Carla; Ruggieri, Maddalena; Trojano, Maria; Mola, Maria Grazia; Nicchia, Grazia Paola; Frigeri, Antonio; Svelto, Maria

    2013-01-01

    Neuromyelitis Optica (NMO) is an autoimmune demyelinating disease, characterized by the presence of autoantibody (NMO-IgG) to Aquaporin-4 (AQP4). NMO-IgG identification supports NMO diagnosis and several diagnostic tests have been developed, but their sensitivity is too variable, and some assay show low sensitivity. This impairs correct diagnosis of NMO. By cell based assay (CBA) we here evaluate the efficacy of different strategies to express AQP4 in mammalian cells in terms of: a) AQP4 translation initiation signals; b) AQP4 isoforms (M1 and M23) and fluorescent tag position; c) NMO serum concentration and AQP4 degradation. Our results demonstrate that when using AQP4-M1, the nucleotide in position -3 of the AUG greatly affects the AQP4-M1/M23 protein ratio, NMO-IgG binding, and consequently test sensitivity. Test sensitivity was highest with M23 expressing cells (97.5%) and only 27.5% with AQP4-M1. The fluorescent tag added to the N-terminus of AQP4-M23 considerably affected the NMO-IgG binding, and test sensitivity, due to disruption of AQP4 suprastructures. Furthermore, sera used at high concentration resulted in AQP4 degradation which affected test sensitivity. To further evaluate the reliability of the M23 based CBA test, samples of one NMO patient collected during about 2 years clinical follow-up were tested. The results of serum titer correlated with disease activity and treatment response. In conclusion, we provide a molecular explanation for the contrasting CBA test data reported and suggest the use of M23 with a C-terminus fluorescent tag as the proper test for NMO diagnosis.

  13. Mutations in AQP5, encoding a water-channel protein, cause autosomal-dominant diffuse nonepidermolytic palmoplantar keratoderma.

    PubMed

    Blaydon, Diana C; Lind, Lisbet K; Plagnol, Vincent; Linton, Kenneth J; Smith, Francis J D; Wilson, Neil J; McLean, W H Irwin; Munro, Colin S; South, Andrew P; Leigh, Irene M; O'Toole, Edel A; Lundström, Anita; Kelsell, David P

    2013-08-08

    Autosomal-dominant diffuse nonepidermolytic palmoplantar keratoderma is characterized by the adoption of a white, spongy appearance of affected areas upon exposure to water. After exome sequencing, missense mutations were identified in AQP5, encoding water-channel protein aquaporin-5 (AQP5). Protein-structure analysis indicates that these AQP5 variants have the potential to elicit an effect on normal channel regulation. Immunofluorescence data reveal the presence of AQP5 at the plasma membrane in the stratum granulosum of both normal and affected palmar epidermis, indicating that the altered AQP5 proteins are trafficked in the normal manner. We demonstrate here a role for AQP5 in the palmoplantar epidermis and propose that the altered AQP5 proteins retain the ability to form open channels in the cell membrane and conduct water.

  14. Aquaporin Expression in Normal and Pathological Skeletal Muscles: A Brief Review with Focus on AQP4

    PubMed Central

    Wakayama, Yoshihiro

    2010-01-01

    Freeze-fracture electron microscopy enabled us to observe the molecular architecture of the biological membranes. We were studying the myofiber plasma membranes of health and disease by using this technique and were interested in the special assembly called orthogonal arrays (OAs). OAs were present in normal myofiber plasma membranes and were especially numerous in fast twitch type 2 myofibers; while OAs were lost from sarcolemmal plasma membranes of severely affected muscles with dystrophinopathy and dysferlinopathy but not with caveolinopathy. In the mid nineties of the last century, the OAs turned out to be a water channel named aquaporin 4 (AQP4). Since this discovery, several groups of investigators have been studying AQP4 expression in diseased muscles. This review summarizes the papers which describe the expression of OAs, AQP4, and other AQPs at the sarcolemma of healthy and diseased muscle and discusses the possible role of AQPs, especially that of AQP4, in normal and pathological skeletal muscles. PMID:20339523

  15. Distinction between MOG antibody-positive and AQP4 antibody-positive NMO spectrum disorders

    PubMed Central

    Sato, Douglas Kazutoshi; Callegaro, Dagoberto; Lana-Peixoto, Marco Aurelio; Waters, Patrick J.; Jorge, Frederico M. de Haidar; Takahashi, Toshiyuki; Nakashima, Ichiro; Apostolos-Pereira, Samira Luisa; Talim, Natalia; Simm, Renata Faria; Lino, Angelina Maria Martins; Misu, Tatsuro; Leite, Maria Isabel; Aoki, Masashi

    2014-01-01

    Objective: To evaluate clinical features among patients with neuromyelitis optica spectrum disorders (NMOSD) who have myelin oligodendrocyte glycoprotein (MOG) antibodies, aquaporin-4 (AQP4) antibodies, or seronegativity for both antibodies. Methods: Sera from patients diagnosed with NMOSD in 1 of 3 centers (2 sites in Brazil and 1 site in Japan) were tested for MOG and AQP4 antibodies using cell-based assays with live transfected cells. Results: Among the 215 patients with NMOSD, 7.4% (16/215) were positive for MOG antibodies and 64.7% (139/215) were positive for AQP4 antibodies. No patients were positive for both antibodies. Patients with MOG antibodies represented 21.1% (16/76) of the patients negative for AQP4 antibodies. Compared with patients with AQP4 antibodies or patients who were seronegative, patients with MOG antibodies were more frequently male, had a more restricted phenotype (optic nerve more than spinal cord), more frequently had bilateral simultaneous optic neuritis, more often had a single attack, had spinal cord lesions distributed in the lower portion of the spinal cord, and usually demonstrated better functional recovery after an attack. Conclusions: Patients with NMOSD with MOG antibodies have distinct clinical features, fewer attacks, and better recovery than patients with AQP4 antibodies or patients seronegative for both antibodies. PMID:24415568

  16. Spatial distributions of AQP5 and AQP0 in embryonic and postnatal mouse lens development

    PubMed Central

    Petrova, Rosica S.; Schey, Kevin L.; Donaldson, Paul J.; Grey, Angus C.

    2015-01-01

    The expression of the water channel protein aquaporin (AQP)-5 in adult rodent and human lenses was recently reported using immunohistochemistry, molecular biology, and mass spectrometry techniques, confirming a second transmembrane water channel that is present in lens fibre cells in addition to the abundant AQP0 protein. Interestingly, the sub-cellular distribution and level of post-translational modification of both proteins changes with fibre cell differentiation and location in the adult rodent lens. This study compares the sub-cellular distribution of AQP0 and AQP5 during embryonic and postnatal fibre cell development in the mouse lens to understand how the immunolabelling patterns for both AQPs observed in adult lens are first established. Immunohistochemistry was used to map the cellular and sub-cellular distribution of AQP5 and AQP0 throughout the lens in cryosections from adult (6 weeks to 8 months) and postnatal (0-2 weeks) mouse lenses and in sections from paraffin embedded mouse embryos (E10-E19). All sections were imaged by fluorescence confocal microscopy. Using antibodies directed against the C-terminus of each AQP, AQP5 was abundantly expressed early in development, being found in the cytoplasm of cells of the lens vesicle and surrounding tissues (E10), while AQP0 was detected later (E11), and only in the membranes of elongating primary fibre cells. During the course of subsequent embryonic and postnatal development the pattern of cytoplasmic AQP5 and membranous AQP0 labelling was maintained until postnatal day 6 (P6). From P6 AQP5 labelling became progressively more membranous initially in the lens nucleus and then later in all regions of the lens, while AQP0 labelling was abruptly lost in the lens nucleus due to C-terminal truncation. Our results show that the spatial distribution patterns of AQP0 and AQP5 observed in the adult lens are established during a narrow window of post natal development (P6-P15) that precedes eye opening and coincides

  17. Clinical utility of testing AQP4-IgG in CSF

    PubMed Central

    Majed, Masoud; Fryer, James P.; McKeon, Andrew; Lennon, Vanda A.

    2016-01-01

    Objective: To define, using assays of optimized sensitivity and specificity, the most informative specimen type for aquaporin-4 immunoglobulin G (AQP4-IgG) detection. Methods: Results were reviewed from longitudinal service testing for AQP4-IgG among specimens submitted to the Mayo Clinic Neuroimmunology Laboratory from 101,065 individual patients. Paired samples of serum/CSF were tested from 616 patients, using M1-AQP4-transfected cell-based assays (both fixed AQP4-CBA Euroimmun kit [commercial CBA] and live in-house flow cytometry [FACS]). Sensitivities were compared for 58 time-matched paired specimens (drawn ≤30 days apart) from patients with neuromyelitis optica (NMO) or high-risk patients. Results: The frequency of CSF submission as sole initial specimen was 1 in 50 in 2007 and 1 in 5 in 2015. In no case among 616 paired specimens was CSF positive and serum negative. In 58 time-matched paired specimens, AQP4-IgG was detected by FACS or by commercial CBA more sensitively in serum than in CSF (respectively, p = 0.06 and p < 0.001). A serum titer >1:100 predicted CSF positivity (p < 0.001). The probability of CSF positivity was greater around attack time (p = 0.03). No control specimen from 128 neurologic patients was positive by either assay. Conclusions: FACS and commercial CBA detection of AQP4-IgG is less sensitive in CSF than in serum. The data suggest that most AQP4-IgG is produced in peripheral lymphoid tissues and that a critical serum/CSF gradient is required for IgG to penetrate the CNS in pathogenic quantity. Serum is the optimal and most cost-effective specimen for AQP4-IgG testing. Classification of evidence: This study provides Class IV evidence that for patients with NMO or NMOSD, CSF is less sensitive than serum for detection of AQP4-IgG. PMID:27144221

  18. Dystrophin-dependent and -independent AQP4 pools are expressed in the mouse brain.

    PubMed

    Nicchia, Grazia Paola; Rossi, Andrea; Nudel, Uri; Svelto, Maria; Frigeri, Antonio

    2008-06-01

    In a recent study, we demonstrated that in the plasma membrane AQP4 is organized into several distinct large multisubunit complexes. In this study, we analysed whether these pools are similarly affected in dystrophin-deficient mice and immunolocalized the sites of dystrophin-dependent and -independent AQP4 pools. Western blot performed on two-dimensional Blue Native/SDS-PAGE membranes indicated that, among the AQP4 pools, it was mainly a large multisubunit complex that was specifically affected in dystrophin-deficient mice (DP71 and mdx3cv mice). This dystrophin-dependent AQP4 pool was immunolocalized in perivascular astrocytes, since it was found to be significantly altered in both types of dystrophin-deficient mice. Dystrophin-independent pools were immunolocalized in the granular cell layer of the cerebellum and in the subpial endfoot layer and ependymal cells in the brain. These data provide a better understanding on the association between AQP4 and the dystrophin-glycoprotein complex in the central nervous system.

  19. Variations in the expression and distribution pattern of AQP5 in acinar cells of patients with sialadenosis.

    PubMed

    Teymoortash, Afshin; Wiegand, Susanne; Borkeloh, Martin; Bette, Michael; Ramaswamy, Annette; Steinbach-Hundt, Silke; Neff, Andreas; Werner, Jochen A; Mandic, Robert

    2012-01-01

    Previously, we pointed out on a possible role of aquaporin 5 (AQP5) in the development of sialadenosis. The goal of the present study was to further assess the association of AQP5 in the development of this salivary gland disease. The acinar diameter and mean surface area appeared elevated in sialadenosis tissues, which is a typical observation in this disease. AQP5 expression was evaluated by immunohistochemistry using tissue samples derived from salivary glands of patients with confirmed sialadenosis either as a primary diagnosis or as a secondary diagnosis within the framework of other salivary gland diseases. Normal salivary gland tissue served as a control. In sialadenosis tissues, the AQP5 signal at the apical plasma membrane of acinar cells frequently appeared stronger compared with that in normal salivary glands. In addition, the distribution of AQP5 at the apical region seemed to differ between normal and sialadenosis tissues, where AQP5 frequently was diffusely distributed near or at the apical plasma membrane of the acinar cells in contrast to normal controls where the AQP5 signal was strictly confined to the apical plasma membrane. These observations suggest that sialadenosis is associated with a different AQP5 expression and distribution pattern in salivary acinar cells.

  20. Translational readthrough generates new astrocyte AQP4 isoforms that modulate supramolecular clustering, glial endfeet localization, and water transport.

    PubMed

    De Bellis, Manuela; Pisani, Francesco; Mola, Maria Grazia; Rosito, Stefania; Simone, Laura; Buccoliero, Cinzia; Trojano, Maria; Nicchia, Grazia Paola; Svelto, Maria; Frigeri, Antonio

    2017-05-01

    Regulation of water homeostasis is a central feature of central nervous system pathophysiology. In this context, several lines of evidence suggest a crucial role for the water channel aquaporin-4 (AQP4) and its plasma membrane supramolecular organization as the key element. Here, we demonstrate the expression in tissues of additional isoforms of AQP4 characterized by a C-terminal extension generated by programmed translational readthrough. These extended isoforms (AQP4ex) display a perivascular polarization and expression in dystrophin-dependent pools. AQP4ex reduces supramolecular clustering tendency and allows AQP4 interactions with syntrophin. Furthermore, site-directed mutagenesis of two serines in the extended C-terminus of AQP4ex showed potential regulation of water permeability by phosphorylation. Finally, AQP4ex expression can be positively modulated by gentamicin treatment, demonstrating the possibility of regulating the AQP4 translational readthrough frequency. This novel regulatory mechanism could have important pathophysiological implications for conditions in which alternations have been reported in AQP4 structure.

  1. Carvacrol alleviates cerebral edema by modulating AQP4 expression after intracerebral hemorrhage in mice.

    PubMed

    Zhong, Zhihong; Wang, Baofeng; Dai, Minchao; Sun, Yuhao; Sun, Qingfang; Yang, Guoyuan; Bian, Liuguan

    2013-10-25

    Carvacrol is a natural compound extracted from many plants of the family Lamiaceae. Previous studies have demonstrated that carvacrol has potential neuroprotective effects in central nervous system diseases such as Alzheimer's disease and cerebral ischemia. In this study, we investigated the preclinical effect of carvacrol on cerebral edema after intracerebral hemorrhage (ICH) using a bacterial collagenase-induced ICH mouse model. Mice were randomly divided into sham (n=43), vehicle-treated (n=51), and carvacrol-treated groups (n=101). In carvacrol-treated group, carvacrol was administrated to mice at 0h, 1h, or 3h after ICH induction. Carvacrol was injected intraperitoneally with single doses of 10, 25, 50, or 100mg/kg. Neurologic dysfunctions, brain water content, aquaporins (AQPs) mRNAs level and AQP4 protein expression in the perihematomal area were evaluated post ICH. Our results showed that carvacrol administration improved neurological deficits after day 3 following ICH (p<0.05). Carvacrol reduced cerebral edema and Evans Blue leakage at day 3 (p<0.05). We also found that carvacrol treatment decreased AQP4 mRNA in a dose-dependent manner at 24h. Furthermore, AQP4 protein expression in the perihematomal area was reduced by carvacrol significantly at day 3 after ICH (p<0.05). Our findings suggest that carvacrol may exert its protective effect on ICH injury by ameliorating AQP4-mediated cerebral edema.

  2. Analysis of AQP4 Trafficking Vesicle Dynamics Using a High-Content Approach

    PubMed Central

    Mazzaferri, Javier; Costantino, Santiago; Lefrancois, Stephane

    2013-01-01

    Aquaporin-4 (AQP4) is found on the basolateral plasma membrane of a variety of epithelial cells, and it is widely accepted that microtubules play an important role in protein trafficking to the plasma membrane. In the particular case of polarized trafficking, however, most evidence on the involvement of microtubules has been obtained via biochemistry experiments and single-shot microscopy. These approaches have provided essential information, even though they neglect the dynamical details of microtubule transport. In this work, we present a high-content framework in which time-lapse imaging, and single-particle-tracking algorithms were used to study a large number (∼104) of GFP-AQP4-carrying vesicles on a large number of cells (∼170). By analyzing several descriptors in this large sample of trajectories, we were able to obtain highly statistically significant results. Our results support the hypothesis that AQP4 is transported along microtubules, but to our surprise, this transport is not directed straight to the basolateral plasma membrane. On the contrary, these vesicles move stochastically along microtubules, changing direction repeatedly. We propose that the role of microtubules in the basolateral trafficking of AQP4 is to increase the efficiency, rather than determine the specificity of the target. PMID:23870254

  3. Accuracy of the Fluorescence-Activated Cell Sorting Assay for the Aquaporin-4 Antibody (AQP4-Ab): Comparison with the Commercial AQP4-Ab Assay Kit

    PubMed Central

    Kim, Yoo-Jin; Cheon, So Young; Kim, Boram; Jung, Kyeong Cheon; Park, Kyung Seok

    2016-01-01

    Background The aquaporin-4 antibody (AQP4-Ab) is a disease-specific autoantibody to neuromyelitis optica (NMO). We aimed to evaluate the accuracy of the FACS assay in detecting the AQP4-Ab compared with the commercial cell-based assay (C-CBA) kit. Methods Human embryonic kidney-293 cells were transfected with human aquaporin-4 (M23) cDNA. The optimal cut off values of FACS assay was tested using 1123 serum samples from patients with clinically definite NMO, those at high risk for NMO, patients with multiple sclerosis, patients with other idiopathic inflammatory demyelinating diseases, and negative controls. The accuracy of FACS assay and C-CBA were compared in consecutive 225 samples that were collected between January 2014 and June 2014. Results With a cut-off value of MFIi of 3.5 and MFIr of 2.0, the receiver operating characteristic curve for the FACS assay showed an area under the curve of 0.876. Among 225 consecutive sera, the FACS assay and C-CBA had a sensitivity of 77.3% and 69.7%, respectively, in differentiating the sera of definite NMO patients from sera of controls without IDD or of MS. Both assay had a good specificity of 100% in it. The overall positivity of the C-CBA among FACS-positive sera was 81.5%; moreover, its positivity was low as 50% among FACS-positive sera with relatively low MFIis. Conclusions Both the FACS assay and C-CBA are sensitive and highly specific assays in detecting AQP4-Ab. However, in some sera with relatively low antibody titer, FACS-assay can be a more sensitive assay option. In real practice, complementary use of FACS assay and C-CBA will benefit the diagnosis of NMO patients, because the former can be more sensitive among low titer sera and the latter are easier to use therefore can be widely used. PMID:27658059

  4. NFAT5 promotes proliferation and migration of lung adenocarcinoma cells in part through regulating AQP5 expression

    SciTech Connect

    Guo, Kai; Jin, Faguang

    2015-09-25

    The osmoregulated transcription factor nuclear factor of activated T-cells 5(NFAT5), has been found to play important roles in the development of many kinds of human cancers, including breast cancer, colon carcinoma, renal cell carcinoma and melanoma. The aim of the present study was to determine whether NFAT5 is involved in the proliferation and migration of lung adenocarcinoma cells. We found that NFAT5 was upregulated in lung adenocarcinoma cells and knockdown of NFAT5 decreased proliferation and migration of the cells, accompanied by a significant reduction in the expression of AQP5. AQP5 was upregulated in lung adenocarcinoma cells and knockdown of AQP5 also inhibited proliferation and migration of the cells as knockdown of NFAT5 did. Moreover, overexpression of NFAT5 promoted proliferation and migration of lung adenocarcinoma cells, accompanied by a significant increase in the expression of AQP5. These results indicate that NFAT5 plays important roles in proliferation and migration of human lung adenocarcinoma cells through regulating AQP5 expression, providing a new therapeutic option for lung adenocarcinoma therapy. - Highlights: • NFAT5 expression is higher in lung adenocarcinoma cells compared with normal cells. • NFAT5 knockdown decreases proliferation and migration of lung adenocarcinoma cells. • Knockdown of NFAT5 reduces AQP5 expression in human lung adenocarcinoma cells. • Overexpression of NFAT5 promotes proliferation and migration of lung adenocarcinoma cells. • Overexpression of NFAT5 increases AQP5 expression in human lung adenocarcinoma cells.

  5. Normal volumes and microstructural integrity of deep gray matter structures in AQP4+ NMOSD

    PubMed Central

    Heine, Josephine; Pache, Florence; Lacheta, Anna; Borisow, Nadja; Kuchling, Joseph; Bellmann-Strobl, Judith; Ruprecht, Klemens; Brandt, Alexander U.; Paul, Friedemann

    2016-01-01

    Objective: To assess volumes and microstructural integrity of deep gray matter structures in a homogeneous cohort of patients with neuromyelitis optica spectrum disorder (NMOSD). Methods: This was a cross-sectional study including 36 aquaporin-4 antibody-positive (AQP4 Ab-positive) Caucasian patients with NMOSD and healthy controls matched for age, sex, and education. Volumetry of deep gray matter structures (DGM; thalamus, caudate, putamen, globus pallidus, hippocampus, amygdala, nucleus accumbens) was performed using 2 independent automated methods. Microstructural integrity was assessed based on diffusion tensor imaging. Results: Both volumetric analysis methods consistently revealed similar volumes of DGM structures in patients and controls without significant group differences. Moreover, no differences in DGM microstructural integrity were observed between groups. Conclusions: Deep gray matter structures are not affected in AQP4 Ab-positive Caucasian patients with NMOSD. NMOSD imaging studies should be interpreted with respect to Ab status, educational background, and ethnicity of included patients. PMID:27144219

  6. Aquaporin-4 antibody testing: direct comparison of M1-AQP4-DNA-transfected cells with leaky scanning versus M23-AQP4-DNA-transfected cells as antigenic substrate

    PubMed Central

    2014-01-01

    Background Neuromyelitis optica (NMO, Devic syndrome) is associated with antibodies to aquaporin-4 (NMO-IgG/AQP4-Ab) in the majority of cases. NMO-IgG/AQP4-Ab seropositivity in patients with NMO and its spectrum disorders has important differential diagnostic, prognostic and therapeutic implications. So-called cell-based assays (CBA) are thought to provide the best AQP4-Ab detection rates. Objective To compare directly the AQP4-IgG detection rates of the currently most widely used commercial CBA, which employs cells transfected with a full-length (M1)-human AQP4 DNA in a fashion that allows leaky scanning (LS) and thus expression of M23-AQP4 in addition to M1-AQP, to that of a newly developed CBA from the same manufacturer employing cells transfected with human M23-AQP4-DNA. Methods Results from 368 serum samples that had been referred for routine AQP4-IgG determination and had been tested in parallel in the two assays were compared. Results Seventy-seven out of 368 samples (20.9%) were positive for NMO-IgG/AQP4-Ab in at least one assay. Of these, 73 (94.8%) were positive in both assays. A single sample (1.3%) was exclusively positive in the novel assay; three samples (3.9%) were unequivocally positive only in the ‘classic’ assay due to high background intensity in the novel assay. Both median fluorescence intensity and background intensity were higher in the new assay. Conclusions This large study did not reveal significant differences in AQP4-IgG detection rates between the ‘classic’ CBA and a new M23-DNA-based CBA. Importantly, our results largely re-affirm the validity of previous studies that had used the ‘classic’ AQP4-CBA to establish NMO-IgG/AQP4-Ab seropositivity rates in NMO and in a variety of NMO spectrum disorders. PMID:25074611

  7. Microstructural visual system changes in AQP4-antibody–seropositive NMOSD

    PubMed Central

    Oertel, Frederike C.; Kuchling, Joseph; Zimmermann, Hanna; Chien, Claudia; Schmidt, Felix; Knier, Benjamin; Bellmann-Strobl, Judith; Korn, Thomas; Scheel, Michael; Klistorner, Alexander; Ruprecht, Klemens; Paul, Friedemann

    2017-01-01

    Objective: To trace microstructural changes in patients with aquaporin-4 antibody (AQP4-ab)-seropositive neuromyelitis optica spectrum disorders (NMOSDs) by investigating the afferent visual system in patients without clinically overt visual symptoms or visual pathway lesions. Methods: Of 51 screened patients with NMOSD from a longitudinal observational cohort study, we compared 6 AQP4-ab–seropositive NMOSD patients with longitudinally extensive transverse myelitis (LETM) but no history of optic neuritis (ON) or other bout (NMOSD-LETM) to 19 AQP4-ab–seropositive NMOSD patients with previous ON (NMOSD-ON) and 26 healthy controls (HCs). Foveal thickness (FT), peripapillary retinal nerve fiber layer (pRNFL) thickness, and ganglion cell and inner plexiform layer (GCIPL) thickness were measured with optical coherence tomography (OCT). Microstructural changes in the optic radiation (OR) were investigated using diffusion tensor imaging (DTI). Visual function was determined by high-contrast visual acuity (VA). OCT results were confirmed in a second independent cohort. Results: FT was reduced in both patients with NMOSD-LETM (p = 3.52e−14) and NMOSD-ON (p = 1.24e−16) in comparison with HC. Probabilistic tractography showed fractional anisotropy reduction in the OR in patients with NMOSD-LETM (p = 0.046) and NMOSD-ON (p = 1.50e−5) compared with HC. Only patients with NMOSD-ON but not NMOSD-LETM showed neuroaxonal damage in the form of pRNFL and GCIPL thinning. VA was normal in patients with NMOSD-LETM and was not associated with OCT or DTI parameters. Conclusions: Patients with AQP4-ab–seropositive NMOSD without a history of ON have microstructural changes in the afferent visual system. The localization of retinal changes around the Müller-cell rich fovea supports a retinal astrocytopathy. PMID:28255575

  8. Expression of multiple AQP4 pools in the plasma membrane and their association with the dystrophin complex.

    PubMed

    Nicchia, Grazia Paola; Cogotzi, Laura; Rossi, Andrea; Basco, Davide; Brancaccio, Andrea; Svelto, Maria; Frigeri, Antonio

    2008-06-01

    Altered aquaporin-4 (AQP4) expression has been reported in brain edema, tumors, muscular dystrophy, and neuromyelitis optica. However, the plasma membrane organization of AQP4 and its interaction with proteins such as the dystrophin-associated protein complex are not well understood. In this study, we used sucrose density gradient ultracentrifugation and 2D blue native/sodium dodecyl sulfate-polyacrylamide gel electrophoresis and showed the expression of several AQP4 multi-subunit complexes (pools) of different sizes, ranging from > 1 MDa to approximately 500 kDa and containing different ratios of the 30/32 kDa AQP4 isoforms, indicative of orthogonal arrays of particles of various sizes. A high molecular weight pool co-purified with dystrophin and beta-dystroglycan and was drastically reduced in the skeletal muscle of mdx3cv mice, which have no dystrophin. The number and size of the AQP4 pools were the same in the kidney where dystrophin is not expressed, suggesting the presence of dystrophin-like proteins for their expression. We found that AQP2 is expressed only in one major pool of approximately 500 kDa, indicating that the presence of different pools is a peculiarity of AQP4 rather than a widespread feature in the AQP family. Finally, in skeletal muscle caveolin-3 did not co-purify with any AQP4 pool, indicating the absence of interaction of the two proteins and confirming that caveolae and orthogonal arrays of particles are two independent plasma membrane microdomains. These results contribute to a better understanding of AQP4 membrane organization and raise the possibility that abnormal expression of specific AQP4 pools may be found in pathological states.

  9. TRPV4 and AQP4 Channels Synergistically Regulate Cell Volume and Calcium Homeostasis in Retinal Müller Glia.

    PubMed

    Jo, Andrew O; Ryskamp, Daniel A; Phuong, Tam T T; Verkman, Alan S; Yarishkin, Oleg; MacAulay, Nanna; Križaj, David

    2015-09-30

    Brain edema formation occurs after dysfunctional control of extracellular volume partly through impaired astrocytic ion and water transport. Here, we show that such processes might involve synergistic cooperation between the glial water channel aquaporin 4 (AQP4) and the transient receptor potential isoform 4 (TRPV4), a polymodal swelling-sensitive cation channel. In mouse retinas, TRPV4 colocalized with AQP4 in the end feet and radial processes of Müller astroglia. Genetic ablation of TRPV4 did not affect the distribution of AQP4 and vice versa. However, retinas from Trpv4(-/-) and Aqp4(-/-) mice exhibited suppressed transcription of genes encoding Trpv4, Aqp4, and the Kir4.1 subunit of inwardly rectifying potassium channels. Swelling and [Ca(2+)]i elevations evoked in Müller cells by hypotonic stimulation were antagonized by the selective TRPV4 antagonist HC-067047 (2-methyl-1-[3-(4-morpholinyl)propyl]-5-phenyl-N-[3-(trifluoromethyl)phenyl]-1H-pyrrole-3-carboxamide) or Trpv4 ablation. Elimination of Aqp4 suppressed swelling-induced [Ca(2+)]i elevations but only modestly attenuated the amplitude of Ca(2+) signals evoked by the TRPV4 agonist GSK1016790A [(N-((1S)-1-{[4-((2S)-2-{[(2,4-dichlorophenyl)sulfonyl]amino}-3-hydroxypropanoyl)-1-piperazinyl]carbonyl}-3-methylbutyl)-1-benzothiophene-2-carboxamide]. Glial cells lacking TRPV4 but not AQP4 showed deficits in hypotonic swelling and regulatory volume decrease. Functional synergy between TRPV4 and AQP4 during cell swelling was confirmed in the heterologously expressing Xenopus oocyte model. Importantly, when the swelling rate was osmotically matched for AQP4-positive and AQP4-negative oocytes, TRPV4 activation became independent of AQP4. We conclude that AQP4-mediated water fluxes promote the activation of the swelling sensor, whereas Ca(2+) entry through TRPV4 channels reciprocally modulates volume regulation, swelling, and Aqp4 gene expression. Therefore, TRPV4-AQP4 interactions constitute a molecular system

  10. Functional down-regulation of volume-regulated anion channels in AQP4 knockdown cultured rat cortical astrocytes.

    PubMed

    Benfenati, Valentina; Nicchia, Grazia Paola; Svelto, Maria; Rapisarda, Carmela; Frigeri, Antonio; Ferroni, Stefano

    2007-01-01

    In the brain, the astroglial syncytium is crucially involved in the regulation of water homeostasis. Accumulating evidence indicates that a dysregulation of the astrocytic processes controlling water homeostasis has a pathogenetic role in several brain injuries. Here, we have analysed by RNA interference technology the functional interactions occurring between the most abundant water channel in the brain, aquaporin-4 (AQP4), and the swelling-activated Cl(-) current expressed by cultured rat cortical astrocytes. We show that in primary cultured rat cortical astrocytes transfected with control small interfering RNA (siRNA), hypotonic shock promotes an increase in cellular volume accompanied by augmented membrane conductance mediated by volume-regulated anion channels (VRAC). Conversely, astroglia in which AQP4 was knocked down (AQP4 KD) by transfection with AQP4 siRNA changed their morphology from polygonal to process-bearing, and displayed normal cell swelling but reduced VRAC activity. Pharmacological manipulations of actin cytoskeleton in rat astrocytes, and functional analysis in mouse astroglial cells, which retain their morphology upon knockdown of AQP4, suggest that stellation of AQP4 KD rat cortical astrocytes was not causally linked to reduction of VRAC current. Molecular analysis of possible candidates of swelling-activated Cl(-) current provided evidence that in AQP4 KD astrocytes, there was a down-regulation of chloride channel-2 (CIC-2), which, however, was not involved in VRAC conductance. Inclusion of ATP in the intracellular saline restored VRAC activity upon hypotonicity. Collectively, these results support the view that in cultured astroglial cells, plasma membrane proteins involved in cell volume homeostasis are assembled in a functional platform.

  11. Characterization of the spectrum of Korean inflammatory demyelinating diseases according to the diagnostic criteria and AQP4-Ab status

    PubMed Central

    2014-01-01

    Background The relative frequencies of demyelinating diseases among Korean patients with idiopathic inflammatory demyelinating disease of the central nervous system (IIDD) have not been sufficiently studied. We therefore describe a cohort of 203 patients with IIDD from three centers in Korea whose syndromes were identified precisely according to international clinical criteria and autoantibody to aquaporin 4 (AQP4-Ab) status. Methods In total, 260 consecutive patients were screened and 203 were included from three hospitals in Korea. All were tested for AQP4-Ab by using a cell-based assay. Patients who met the criteria for definite neuromyelitis optica (NMO) or had a positive AQP4-Ab test result were defined as the NMO group. Among the others, patients were assessed if they had acute disseminated encephalomyelitis, multiple sclerosis (MS), acute transverse myelitis, optic neuritis, or other demyelinating disease as a clinically isolated syndrome of the brain. Results Eighteen percent of patients were classified as the NMO group, 2% as acute disseminated encephalomyelitis, 18% as MS, 41% as acute transverse myelitis, 11% as optic neuritis, and 8% as other clinically isolated syndrome of the brain. AQP4-Ab was positive in 18% of patients and the relative frequency of NMO to MS (NMO/MS ratio) was 1.06. The mean duration of follow up in our patients was 64 months. Conclusions Among Korean patients with idiopathic inflammatory demyelinating diseases, the incidence of NMO may be similar to that of MS, and the overall positivity of AQP4-Ab could be lower than previously reported. In addition, acute transverse myelitis that is not associated with MS or NMO can be relatively common in these patients. Further population-based studies with AQP4-Ab are needed to determine the exact incidence of NMO and other idiopathic inflammatory demyelinating diseases in Korea. PMID:24779645

  12. Effect of progesterone intervention on the dynamic changes of AQP-4 in hypoxic-ischaemic brain damage

    PubMed Central

    Li, Xiaojuan; Bai, Ruiying; Zhang, Junhe; Wang, Xiaoyin

    2015-01-01

    To observe the effect of progesterone (PROG) on blood-brain barrier (BBB) permeability, brain tissue water content and dynamic changes of aquaporin-4 (AQP-4) in neonatal rats with hypoxic-ischaemic brain damage (HIBD). 72 neonatal Wistar rats, aged 7 days old, were randomly divided into control, hypoxic-ischaemic (6, 24 and 72 h, and 7 d subgroups) and drug groups (6, 24 and 72 h, and 7 d subgroups). The HIBD animal model was established. BBB was detected via an Evans blue tracer. Brain water content was determined by the dry/wet method. The AQP-4 expression in the cerebral cortex was observed through immunohistochemistry and Western blot. BBB permeability in the cerebral cortex of the neonatal rats, brain water content and AQP-4 expression in the hypoxia-ischaemia group were significantly higher than those of the control group after hypoxia for 6 h (P < 0.05), continued to rise within 24 h and then reached the peak at 72 h. BBB permeability in the cerebral cortex of the neonatal rats, brain water content and AQP-4 expression in the drug group were significantly lower than those of the hypoxia-ischaemia group after hypoxia for 6, 24 and 72 h (P < 0.05). Moreover, BBB permeability and BBB expression were positively correlated with the AQP-4 expression. In conclusion, PROG protects the brain of HIBD neonatal rats by alleviating the damage of BBB and cerebral oedema. The protective effect of PROG may be related to the down-regulation of AQP-4 expression in the cerebral cortex of neonatal rats. PMID:26770503

  13. Berberine increases the expression of NHE3 and AQP4 in sennosideA-induced diarrhoea model.

    PubMed

    Zhang, Yongguo; Wang, Xin; Sha, Sumei; Liang, Shuli; Zhao, Lina; Liu, Lin; Chai, Na; Wang, Honghong; Wu, Kaichun

    2012-09-01

    Berberine, a compound isolated from Chinese Goldthread Rhizome, has been widely used as a non-prescription drug to treat diarrhoea in China. Previous studies have demonstrated multiple pharmacological activities for berberine, including its significant role in antimicrobial activity. However, its effect on ion exchange and water transfer remains unclear. The present study aims to explore the effect of berberine on the expression of Na(+)/H(+) exchanger3 (NHE3) and aquaporin4 (AQP4) in both diarrhoea mouse model induced by sennosideA and human intestinal epithelium cell line (HIEC). Semi-quantitative RT-PCR, immunohistochemistry and western blotting were adopted to detect the mRNA and protein expression levels of NHE3 and AQP4. Furthermore, the absorption of berberine and the PKC activity were detected by HPLC and PepTag® Assay to elucidate the underlying mechanisms. It was shown that the expression levels of NHE3 and AQP4 were significantly increased in the diarrhoea mice treated with berberine compared with the untreated diarrhoea mice. Similarly, the expression levels of NHE3 and AQP4 were strikingly enhanced in HIEC co-treated with sennosideA and berberine compared with samples treated with sennosideA only. We also found the maximal absorption of berberine to be approximately 0.01%. In addition, no significant change of PKC activity was observed in the different HIEC treated groups. These results showed that berberine was able to increase the expression of NHE3 and AQP4, suggesting that berberine might exhibit its anti-diarrhoeal effect partially by enhancing the absorption of Na(+) and water.

  14. Antibodies to MOG and AQP4 in adults with neuromyelitis optica and suspected limited forms of the disease

    PubMed Central

    Armangue, Thaís; Blanco, Yolanda; Rostásy, Kevin; Calvo, Alvaro Cobo; Olascoaga, Javier; Ramió-Torrentà, Lluís; Reindl, Markus; Benito-León, Julián; Casanova, Bonaventura; Arrambide, Georgina; Sabater, Lidia; Graus, Francesc; Dalmau, Josep; Saiz, Albert

    2016-01-01

    Objective We aimed to report the frequency and implications of antibodies to myelin oligodendrocyte glycoprotein (MOG-ab) in adults with demyelinating syndromes suspicious for neuromyelitis optica (NMO). Methods Samples from 174 patients (48 NMO, 84 longitudinally extensive myelitis (LETM), 39 optic neuritis (ON), and three acute disseminated encephalomyelitis (ADEM) who presented initially with isolated LETM) were retrospectively examined for AQP4-ab and MOG-ab using cell-based assays. Results MOG-ab were found in 17 (9.8%) patients, AQP4-ab in 59 (34%), and both antibodies in two (1.1%). Among the 17 patients with MOG-ab alone, seven (41%) had ON, five (29%) LETM, four (24%) NMO, and one (6%) ADEM. Compared with patients with AQP4-ab, those with MOG-ab were significantly younger (median: 27 vs. 40.5 years), without female predominance (53% vs. 90%), and the clinical course was more frequently monophasic (41% vs. 7%) with a benign outcome (median Expanded Disability Status Scale: 1.5 vs. 4.0). In eight patients with paired serum-cerebrospinal fluid (CSF) samples, five had MOG-ab in both samples and three only in serum. Antibody titres did not differ among clinical phenotypes or disease course. MOG-ab remained detectable in 12/14 patients (median follow-up: 23 months) without correlation between titres' evolution and outcome. Conclusion MOG-ab identify a subgroup of adult patients with NMO, LETM and ON that have better outcome than those associated with AQP4-ab. MOG-ab are more frequently detected in serum than CSF and the follow-up of titres does not correlate with outcome. PMID:25344373

  15. Simvastatin pretreatment protects cerebrum from neuronal injury by decreasing the expressions of phosphor-CaMK II and AQP4 in ischemic stroke rats.

    PubMed

    Zhu, Min-xia; Lu, Chao; Xia, Chun-mei; Qiao, Zhong-wei; Zhu, Da-nian

    2014-12-01

    Excitotoxicity and cytotoxic edema are the two major factors resulting in neuronal injury during brain ischemia and reperfusion. Ca2+/calmodulin-dependent protein kinase II (CaMK II), the downstream signal molecular of N-methyl-D-aspartate receptors (NMDARs), is a mediator in the excitotoxicity. Aquaporin 4 (AQP4), expressed mainly in the brain, is an important aquaporin to control the flux of water. In a previous study, we had reported that pretreatment of simvastatin protected the cerebrum from ischemia and reperfusion injury by decreasing neurological deficit score and infarct area (Zhu et al. PLoS One 7:e51552, 2012). The present study used a middle cerebral artery occlusion (MCAO) model to further explore the pleiotropic effect of simvastatin via CaMK II and AQP4. The results showed that simvastatin reduced degenerated cells and brain edema while decreasing the protein expressions of phosphor-CaMK II and AQP4, and increasing the ratios of Bcl-2/Bax, which was independent of cholesterol-lowering effect. Immunocomplexes formed between the subunit of NMDARs-NR3A and AQP4 were detected for the first time. It was concluded that simvastatin could protect the cerebrum from neuronal excitotoxicity and cytotoxic edema by downregulating the expressions of phosphor-CaMK II and AQP4, and that the interaction between NR3A and AQP4 might provide the base for AQP4 involving in the signaling pathways mediated by NMDARs.

  16. Mechanisms Underlying Activation of α1-Adrenergic Receptor-Induced Trafficking of AQP5 in Rat Parotid Acinar Cells under Isotonic or Hypotonic Conditions

    PubMed Central

    Bragiel, Aneta M.; Wang, Di; Pieczonka, Tomasz D.; Shono, Masayuki; Ishikawa, Yasuko

    2016-01-01

    Defective cellular trafficking of aquaporin-5 (AQP5) to the apical plasma membrane (APM) in salivary glands is associated with the loss of salivary fluid secretion. To examine mechanisms of α1-adrenoceptor (AR)-induced trafficking of AQP5, immunoconfocal microscopy and Western blot analysis were used to analyze AQP5 localization in parotid tissues stimulated with phenylephrine under different osmolality. Phenylephrine-induced trafficking of AQP5 to the APM and lateral plasma membrane (LPM) was mediated via the α1A-AR subtype, but not the α1B- and α1D-AR subtypes. Phenylephrine-induced trafficking of AQP5 was inhibited by ODQ and KT5823, inhibitors of nitric oxide (NO)-stimulated guanylcyclase (GC) and protein kinase (PK) G, respectively, indicating the involvement of the NO/ soluble (c) GC/PKG signaling pathway. Under isotonic conditions, phenylephrine-induced trafficking was inhibited by La3+, implying the participation of store-operated Ca2+ channel. Under hypotonic conditions, phenylephrine-induced trafficking of AQP5 to the APM was higher than that under isotonic conditions. Under non-stimulated conditions, hypotonicity-induced trafficking of AQP5 to the APM was inhibited by ruthenium red and La3+, suggesting the involvement of extracellular Ca2+ entry. Thus, α1A-AR activation induced the trafficking of AQP5 to the APM and LPM via the Ca2+/ cyclic guanosine monophosphate (cGMP)/PKG signaling pathway, which is associated with store-operated Ca2+ entry. PMID:27367668

  17. Hypoxia and Hypoxia Mimetics Decrease Aquaporin 5 (AQP5) Expression through Both Hypoxia Inducible Factor-1α and Proteasome-Mediated Pathways

    PubMed Central

    Kawedia, Jitesh D.; Yang, Fan; Sartor, Maureen A.; Gozal, David; Czyzyk-Krzeska, Maria; Menon, Anil G.

    2013-01-01

    The alveolar epithelium plays a central role in gas exchange and fluid transport, and is therefore critical for normal lung function. Since the bulk of water flux across this epithelium depends on the membrane water channel Aquaporin 5 (AQP5), we asked whether hypoxia had any effect on AQP5 expression. We show that hypoxia causes a significant (70%) decrease in AQP5 expression in the lungs of mice exposed to hypoxia. Hypoxia and the hypoxia mimetic, cobalt, also caused similar decreases in AQP5 mRNA and protein expression in the mouse lung epithelial cell line MLE-12. The action of hypoxia and cobalt on AQP5 transcription was demonstrated by directly quantifying heternonuclear RNA by real-time PCR. Dominant negative mutants of Hypoxia Inducible Factor (HIF-1α) and HIF-1α siRNA blocked the action of cobalt, showing that HIF-1α is a key component in this mechanism. The proteasome inhibitors, lactacystin or proteasome inhibitor-III completely abolished the effect of hypoxia and cobalt both at the protein and mRNA level indicating that the proteasome pathway is probably involved not only for the stability of HIF-1α protein, but for the stability of unidentified transcription factors that regulate AQP5 transcription. These studies reveal a potentially important physiological mechanism linking hypoxic stress and membrane water channels. PMID:23469202

  18. 'Hit & Run' model of closed-skull traumatic brain injury (TBI) reveals complex patterns of post-traumatic AQP4 dysregulation.

    PubMed

    Ren, Zeguang; Iliff, Jeffrey J; Yang, Lijun; Yang, Jiankai; Chen, Xiaolin; Chen, Michael J; Giese, Rebecca N; Wang, Baozhi; Shi, Xuefang; Nedergaard, Maiken

    2013-06-01

    Cerebral edema is a major contributor to morbidity associated with traumatic brain injury (TBI). The methods involved in most rodent models of TBI, including head fixation, opening of the skull, and prolonged anesthesia, likely alter TBI development and reduce secondary injury. We report the development of a closed-skull model of murine TBI, which minimizes time of anesthesia, allows the monitoring of intracranial pressure (ICP), and can be modulated to produce mild and moderate grade TBI. In this model, we characterized changes in aquaporin-4 (AQP4) expression and localization after mild and moderate TBI. We found that global AQP4 expression after TBI was generally increased; however, analysis of AQP4 localization revealed that the most prominent effect of TBI on AQP4 was the loss of polarized localization at endfoot processes of reactive astrocytes. This AQP4 dysregulation peaked at 7 days after injury and was largely indistinguishable between mild and moderate grade TBI for the first 2 weeks after injury. Within the same model, blood-brain barrieranalysis of variance permeability, cerebral edema, and ICP largely normalized within 7 days after moderate TBI. These findings suggest that changes in AQP4 expression and localization may not contribute to cerebral edema formation, but rather may represent a compensatory mechanism to facilitate its resolution.

  19. Differential Expression of AQP1 and AQP4 in Avascular Chick Retina Exposed to Moderate Light of Variable Photoperiods.

    PubMed

    Jha, Kumar Abhiram; Nag, Tapas Chandra; Kumar, Vivek; Kumar, Pankaj; Kumar, Binit; Wadhwa, Shashi; Roy, Tara Sankar

    2015-11-01

    Aquaporins (AQPs) are integral membrane proteins which maintain cellular water and ion homeostasis. Alterations in AQP expression have been reported in rod-dominated rodent retinas exposed to light. In rodents and also in birds, light of moderate intensities (700-2000 lux) damages the retina, though detailed changes were not examined in birds. The aim of our study was to see if light affects cone dominated retinas, which would be reflected in expression levels of AQPs. We examined AQP1 and AQP4 expressions in chick retina exposed to 2000 lux under 12 h light:12 h dark (12L:12D; normal photoperiod), 18L:6D (prolonged photoperiod) and 24L:0D (constant light). Additionally, morphological changes, apoptosis (by TUNEL) and levels of glutamate and GFAP (a marker of injury) in the retina were examined to correlate these with AQP expressions. Constant light caused damage in outer and inner nuclear layer (ONL, INL) and ganglion cell layer (GCL). Also, there were associated increases in GFAP and glutamate levels in retinal extracts. In normal photoperiod, AQP1 was expressed in GCL, outer part of INL and photoreceptor inner segments of. AQP4 was additionally expressed in nerve fiber layer. Immunohistochemistry and Western blotting revealed over all decreased AQP1 and AQP4 expression in constant light condition compared to those in other two groups. The elevated GFAP and glutamate levels might be involved in the reduction of AQPs in constant light group. Such decreases in AQP expressions are perhaps linked with retinal cell damage seen in constant light condition, while their relatively enhanced expression in two other conditions may help in maintaining a normal retinal architecture, indicating their neuroprotective potential.

  20. Periplasmic Vestibule Determines the Ligand Selectivity in E.Coli AMTB

    NASA Astrophysics Data System (ADS)

    Akgun, Ugur; Khademi, Shahram

    2010-03-01

    The transport of ammonia, fundamental to the nitrogen metabolism in all domains of life, is carried out by the Rh/Amt/MEP membrane protein superfamily. The first structure of this family, AmtB from E.Coli shows a pathway for ammonia that includes two vestibules connected by a long and narrow hydrophobic lumen. The accepted mechanism for AmtB is to recruit NH4^+ and conduct neutral NH3 by deprotonation of NH4^+ at the end of periplasmic vestibule. Here we report from various MD simulations performed using a model of trimeric AmtB embedded into POPE lipid bilayer to determine the mechanism of ligands selectivity and conduction in the ammonia channels. Our total more than 500ns simulations reveal that the AmtB periplasmic vestibule prefers NH4^+ over NH3 and CO2. And the rate of ammonia conduction is regulated by the motion of the phenyl rings at the bottom of the vestibule. We also report that the conserved D160 is essential for ligand conduction by stabilizing the NH4^+ at the recruitment site through charge interactions. Our simulations also suggest NH4^+ most likely releases its proton to the bulk of water as it enters to the hydrophobic lumen.

  1. Retinal Nerve Fiber Layer May Be Better Preserved in MOG-IgG versus AQP4-IgG Optic Neuritis: A Cohort Study

    PubMed Central

    Chodick, Gabriel; Bialer, Omer; Marignier, Romain; Bach, Michael; Hellmann, Mark Andrew

    2017-01-01

    Background Optic neuritis (ON) in patients with anti-myelin oligodendrocyte glycoprotein (MOG)-IgG antibodies has been associated with a better clinical outcome than anti-aquaporin 4 (AQP4)- IgG ON. Average retinal nerve fiber layer thickness (RNFL) correlates with visual outcome after ON. Objectives The aim of this study was to examine whether anti-MOG-IgG ON is associated with better average RNFL compared to anti-AQP4-IgG ON, and whether this corresponds with a better visual outcome. Methods A retrospective study was done in a consecutive cohort of patients following anti-AQP4-IgG and anti-MOG-IgG ON. A generalized estimating equation (GEE) models analysis was used to compare average RNFL outcomes in ON eyes of patients with MOG-IgG to AQP4-IgG-positive patients, after adjusting for the number of ON events. The final mean visual field defect and visual acuity were compared between ON eyes of MOG-IgG and AQP4-IgG-positive patients. A correlation between average RNFL and visual function was performed in all study eyes. Results Sixteen patients were analyzed; ten AQP4-IgG-positive and six MOG-IgG-positive. The six patients with MOG-IgG had ten ON events with disc edema, five of which were bilateral. In the AQP4-IgG-positive ON events, 1/10 patients had disc edema. Final average RNFL was significantly better in eyes following MOG-IgG-ON (75.33μm), compared to 63.63μm in AQP4-IgG-ON, after adjusting for the number of ON attacks (GEE, p = 0.023). Mean visual field defects were significantly smaller (GEE, p = 0.046) among MOG-IgG positive ON eyes compared to AQP-IgG positive ON eyes, but last visual acuity did not differ between the groups (GEE, p = 0.153). Among all eyes, average RNFL positively correlated with mean visual field defect (GEE, p = 0.00015) and negatively correlated with final visual acuity (GEE, p = 0.00005). Conclusions Following ON, RNFL is better preserved in eyes of patients with MOG-IgG antibodies compared to those with AQP4-IgG antibodies

  2. Distribution of the AQP4 water channel in normal human tissues: protein and tissue microarrays reveal expression in several new anatomical locations, including the prostate gland and seminal vesicles.

    PubMed

    Mobasheri, Ali; Marples, David; Young, Iain S; Floyd, Rachel V; Moskaluk, Christopher A; Frigeri, Antonio

    2007-01-01

    Aquaporins facilitate osmotically driven water movement across cell membranes. Aquaporin 4 (AQP4) is a major water channel in the central nervous system where it participates in cerebral water balance. AQP4 is also present in basolateral membranes of lower respiratory tract airway and renal collecting duct epithelial cells, gastric parietal cells and skeletal muscle cells. However, the distribution of AQP4 in many other tissues is still unknown. The aim of this study was to determine the expression and relative abundance of AQP4 in human Tissue MicroArrays (TMAs) and human protein microarrays by immunohistochemistry and chemiluminescence. In the central nervous system AQP4 was abundantly expressed in the cerebral cortex, cerebellar cortex (purkinje/granular layer), ependymal cell layer, hippocampus and spinal cord. Lower levels were detected in choroid plexus, white matter and meninges. In the musculoskeletal system AQP4 was highly expressed in the sarcolemma of skeletal muscle from the chest and neck. In the male genital system AQP4 was moderately expressed in seminiferous tubules, seminal vesicles, prostate and epidiymis. In the respiratory system AQP4 was moderately expressed in lung and bronchus. AQP expression was abundant in the kidney. In the gastrointestinal system AQP4 was moderately present in basolateral membranes of parietal cells at the base of gastric glands. AQP4 was also detected in salivary glands, adrenals, anterior pituitary, prostate and seminal vesicles. Human protein microarrays verified the TMA data. Our findings suggest that AQP4 is expressed more widely than previously thought in human organs and may be involved in prostatic and seminal fluid formation.

  3. Gene expression and localization of two types of AQP5 in Xenopus tropicalis under hydration and dehydration.

    PubMed

    Shibata, Yuki; Sano, Takahiro; Tsuchiya, Nobuhito; Okada, Reiko; Mochida, Hiroshi; Tanaka, Shigeyasu; Suzuki, Masakazu

    2014-07-01

    Two types of aquaporin 5 (AQP5) genes (aqp-xt5a and aqp-xt5b) were identified in the genome of Xenopus tropicalis by synteny comparison and molecular phylogenetic analysis. When the frogs were in water, AQP-xt5a mRNA was expressed in the skin and urinary bladder. The expression of AQP-xt5a mRNA was significantly increased in dehydrated frogs. AQP-xt5b mRNA was also detected in the skin and increased in response to dehydration. Additionally, AQP-xt5b mRNA began to be slightly expressed in the lung and stomach after dehydration. For the pelvic skin of hydrated frogs, immunofluorescence staining localized AQP-xt5a and AQP-xt5b to the cytoplasm of secretory cells of the granular glands and the apical plasma membrane of secretory cells of the small granular glands, respectively. After dehydration, the locations of both AQPs in their respective glands did not change, but AQP-xt5a was visualized in the cytoplasm of secretory cells of the small granular glands. For the urinary bladder, AQP-xt5a was observed in the apical plasma membrane and cytoplasm of a number of granular cells under normal hydration. After dehydration, AQP-xt5a was found in the apical membrane and cytoplasm of most granular cells. Injection of vasotocin into hydrated frogs did not induce these changes in the localization of AQP-xt5a in the small granular glands and urinary bladder, however. The results suggest that AQP-xt5a might be involved in water reabsorption from the urinary bladder during dehydration, whereas AQP-xt5b might play a role in water secretion from the small granular gland.

  4. The pivotal twin histidines and aromatic triad of the Escherichia coli ammonium channel AmtB can be replaced.

    PubMed

    Hall, Jason A; Kustu, Sydney

    2011-08-09

    In Escherichia coli, each subunit of the trimeric channel protein AmtB carries a hydrophobic pore for transport of NH(4)(+) across the cytoplasmic membrane. Positioned along this substrate conduction pathway are two conserved elements--a pair of hydrogen-bonded histidines (H168/H318) located within the pore itself and a set of aromatic residues (F107/W148/F215) at its periplasmic entrance--thought to be critical to AmtB function. Using site-directed mutagenesis and suppressor genetics, we examined the requirement for these elements in NH(4)(+) transport. This analysis shows that AmtB can accommodate, by either direct substitution or suppressor generation, acidic residues at one or both positions of the H168/H318 twin-histidine site while retaining near wild-type activity. Similarly, study of the F107/W148/F215 triad indicates that good-to-excellent AmtB function is preserved upon individual and simultaneous replacement of these aromatic amino acids with aliphatic residues. Our findings lead us to conclude that these elements and their component parts are not required for AmtB function, but instead serve to optimize its performance.

  5. Age-Related Modulations of AQP4 and Caveolin-1 in the Hippocampus Predispose the Toxic Effect of Phoneutria nigriventer Spider Venom

    PubMed Central

    Soares, Edilene S.; Stávale, Leila M.; Mendonça, Monique C. P.; Coope, Andressa; da Cruz-Höfling, Maria Alice

    2016-01-01

    We have previously demonstrated that Phoneutria nigriventer venom (PNV) causes blood–brain barrier (BBB) breakdown, swelling of astrocytes end-feet and fluid permeation into brain interstitium in rats. Caveolae and water channels respond to BBB alterations by co-participation in shear stress response and edema formation/resolution. Herein, we showed post-natal developmental-related changes of two BBB-associated transporter proteins: the endothelial caveolin-1 (Cav-1), the major scaffolding protein from caveolae frame, and the astroglial aquaporin-4 (AQP4), the main water channel protein expressed in astrocytic peri-vascular end-feet processes, in the hippocampus of rats intraperitoneally-administered PNV. Western blotting protein levels; immunohistochemistry (IHC) protein distribution in CA1, CA2, and CA3 subfields; and gene expression by Real Time-Polymerase Chain Reaction (qPCR) were assessed in post-natal Day 14 (P14) and 8–10-week-old rats over critical periods of envenomation. The intensity and duration of the toxic manifestations indicate P14 neonate rats more vulnerable to PNV than adults. Histologically, the capillaries of P14 and 8–10-week-old rats treated with PNV showed perivascular edema, while controls did not. The intensity of the toxic manifestations in P14 decreases temporally (2 > 5 > 24 h), while inversely the expression of AQP4 and Cav-1 peaked at 24 h when clinically PNV-treated animals do not differ from saline controls. IHC of AQP4 revealed that hippocampal CA1 showed the least expression at 2 h when toxic manifestation was maximal. Subfield IHC quantification revealed that in P14 rats Cav-1 peaked at 24 h when toxic manifestations were absent, whereas in 8–10-week-old rats Cav-1 peaked at 2 h when toxic signs were highest, and progressively attenuated such increases until 24 h, remaining though significantly above baseline. Considering astrocyte-endothelial physical and functional interactions, we hypothesize that age

  6. Dexmedetomidine alleviates pulmonary edema by upregulating AQP1 and AQP5 expression in rats with acute lung injury induced by lipopolysaccharide.

    PubMed

    Jiang, Yuan-xu; Dai, Zhong-liang; Zhang, Xue-ping; Zhao, Wei; Huang, Qiang; Gao, Li-kun

    2015-10-01

    This study aims to elucidate the mechanisms by which dexmedetomidine alleviates pulmonary edema in rats with acute lung injury induced by lipopolysaccharide (LPS). Male Wistar rats were randomly divided into five groups: normal saline control (NS) group, receiving intravenous 0.9% normal saline (5 mL/kg); LPS group, receiving intravenous LPS (10 mg/kg); small-dose dexmedetomidine (S) group, treated with a small dose of dexmedetomidine (0.5 μg · kg(-1) · h(-1)); medium-dose dexmedetomidine (M) group, treated with a medium dose of dexmedetomidine (2.5 μg · kg(-1) · h(-1)); high-dose dexmedetomidine (H) group, treated with a high dose of dexmedetomidine (5 μg · kg(-1) · h(-1)). The rats were sacrificed 6 h after intravenous injection of LPS or NS, and the lungs were removed for evaluating histological characteristics and determining the lung wet/dry weight ratio (W/D). The levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) in the lung tissues were assessed by enzyme- linked immunosorbent assay (ELISA). The mRNA and protein expression levels of aquaporin-1 (AQP1) and aquaporin-5 (AQP5) were detected by RT-PCR, immunohistochemistry, and Western blotting. The lung tissues from the LPS groups were significantly damaged, which were less pronounced in the H group but not in the small-dose dexmedetomidine group or medium-dose dexmedetomidine group. The W/D and the concentrations of TNF-α and IL-1β in the pulmonary tissues were increased in the LPS group as compared with those in NS group, which were reduced in the H group but not in S group or M group (P<0.01). The expression of AQP1 and AQP5 was lower in the LPS group than in the NS group, and significantly increased in the H group but not in the S group or M group (P<0.01). Our findings suggest that dexmedetomidine may alleviate pulmonary edema by increasing the expression of AQP-1 and AQP-5.

  7. Co-localisation of K(ir)4.1 and AQP4 in rat and human cochleae reveals a gap in water channel expression at the transduction sites of endocochlear K(+) recycling routes.

    PubMed

    Eckhard, Andreas; Gleiser, Corinna; Rask-Andersen, Helge; Arnold, Heinz; Liu, Wei; Mack, Andreas; Müller, Marcus; Löwenheim, Hubert; Hirt, Bernhard

    2012-10-01

    Sensory transduction in the cochlea depends on perilymphatic-endolymphatic potassium (K(+)) recycling. It has been suggested that the epithelial supporting cells (SCs) of the cochlear duct may form the intracellular K(+) recycling pathway. Thus, they must be endowed with molecular mechanisms that facilitate K(+) uptake and release, along with concomitant osmotically driven water movements. As yet, no molecules have been described that would allow for volume-equilibrated transepithelial K(+) fluxes across the SCs. This study describes the subcellular co-localisation of the K(ir)4.1 K(+) channel (K(ir)4.1) and the aquaporin-4 water channel (AQP4) in SCs, on the basis of immunohistochemical double-labelling experiments in rat and human cochleae. The results of this study reveal the expression of K(ir)4.1 in the basal or basolateral membranes of the SCs in the sensory domain of the organ of Corti that are adjacent to hair cells and in the non-sensory domains of the inner and outer sulci that abut large extracellular fluid spaces. The SCs of the inner sulcus (interdental cells, inner sulcus cells) and the outer sulcus (Hensen's cells, outer sulcus cells) display the co-localisation of K(ir)4.1 and AQP4 expression. However, the SCs in the sensory domain of the organ of Corti reveal a gap in the expression of AQP4. The outer pillar cell is devoid of both K(ir)4.1 and AQP4. The subcellular co-localisation of K(ir)4.1 and AQP4 in the SCs of the cochlea described in this study resembles that of the astroglia of the central nervous system and the glial Mueller cells in the retina.

  8. Inhibition and transcriptional silencing of a subtilisin-like proprotein convertase, PACE4/SPC4, reduces the branching morphogenesis of and AQP5 expression in rat embryonic submandibular gland.

    PubMed

    Akamatsu, Tetsuya; Azlina, Ahmad; Purwanti, Nunuk; Karabasil, Mileva Ratko; Hasegawa, Takahiro; Yao, Chenjuan; Hosoi, Kazuo

    2009-01-15

    The submandibular gland (SMG) develops through the epithelial-mesenchymal interaction mediated by many growth/differentiation factors including activin and BMPs, which are synthesized as inactive precursors and activated by subtilisin-like proprotein convertases (SPC) following cleavage at their R-X-K/R-R site. Here, we found that Dec-RVKR-CMK, a potent inhibitor of SPC, inhibited the branching morphogenesis of the rat embryonic SMG, and caused low expression of a water channel AQP5, in an organ culture system. Dec-RVKR-CMK also decreased the expression of PACE4, a SPC member, but not furin, another SPC member, suggesting the involvement of PACE4 in the SMG development. Heparin, which is known to translocate PACE4 in the extracellular matrix into the medium, and an antibody specific for the catalytic domain of PACE4, both reduced the branching morphogenesis and AQP5 expression in the SMG. The inhibitory effects of Dec-RVKR-CMK were partially rescued by the addition of recombinant BMP2, whose precursor is one of the candidate substrates for PACE4 in vivo. Further, the suppression of PACE4 expression by siRNAs resulted in decreased expression of AQP5 and inhibition of the branching morphogenesis in the present organ culture system. These observations suggest that PACE4 regulates the SMG development via the activation of some growth/differentiation factors.

  9. Selective vasopressin-1a receptor antagonist prevents brain edema, reduces astrocytic cell swelling and GFAP, V1aR and AQP4 expression after focal traumatic brain injury.

    PubMed

    Marmarou, Christina R; Liang, Xiuyin; Abidi, Naqeeb H; Parveen, Shanaz; Taya, Keisuke; Henderson, Scott C; Young, Harold F; Filippidis, Aristotelis S; Baumgarten, Clive M

    2014-09-18

    A secondary and often lethal consequence of traumatic brain injury is cellular edema that we posit is due to astrocytic swelling caused by transmembrane water fluxes augmented by vasopressin-regulated aquaporin-4 (AQP4). We therefore tested whether vasopressin 1a receptor (V1aR) inhibition would suppress astrocyte AQP4, reduce astrocytic edema, and thereby diminish TBI-induced edematous changes. V1aR inhibition by SR49059 significantly reduced brain edema after cortical contusion injury (CCI) in rat 5h post-injury. Injured-hemisphere brain water content (n=6 animals/group) and astrocytic area (n=3/group) were significantly higher in CCI-vehicle (80.5±0.3%; 18.0±1.4 µm(2)) versus sham groups (78.3±0.1%; 9.5±0.9 µm(2)), and SR49059 blunted CCI-induced increases in brain edema (79.0±0.2%; 9.4±0.8µm(2)). CCI significantly up-regulated GFAP, V1aR and AQP4 protein levels and SR49059 suppressed injury induced up regulation (n=6/group). In CCI-vehicle, sham and CCI-SR49059 groups, GFAP was 1.58±0.04, 0.47±0.02, and 0.81±0.03, respectively; V1aR was 1.00±0.06, 0.45±0.05, and 0.46±0.09; and AQP4 was 2.03±0.34, 0.49±0.04, and 0.92±0.22. Confocal immunohistochemistry gave analogous results. In CCI-vehicle, sham and CCI-SR49059 groups, fluorescence intensity of GFAP was 349±38, 56±5, and 244±30, respectively, V1aR was 601±71, 117.8±14, and 390±76, and AQP4 was 818±117, 158±5, and 458±55 (n=3/group). The results support that edema was predominantly cellular following CCI and documented that V1aR inhibition with SR49059 suppressed injury-induced up regulation of GFAP, V1A and AQP4, blunting edematous changes. Our findings suggest V1aR inhibitors may be potential therapeutic tools to prevent cellular swelling and provide treatment for post-traumatic brain edema.

  10. Therapeutic effects of Euphorbia Pekinensis and Glycyrrhiza glabra on Hepatocellular Carcinoma Ascites Partially Via Regulating the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 Signal Axis

    PubMed Central

    Zhang, Yanqiong; Yan, Chen; Li, Yuting; Mao, Xia; Tao, Weiwei; Tang, Yuping; Lin, Ya; Guo, Qiuyan; Duan, Jingao; Lin, Na

    2017-01-01

    To clarify unknown rationalities of herbaceous compatibility of Euphorbia Pekinensis (DJ) and Glycyrrhiza glabra (GC) acting on hepatocellular carcinoma (HCC) ascites, peritoneum transcriptomics profiling of 15 subjects, including normal control (Con), HCC ascites mouse model (Mod), DJ-alone, DJ/GC-synergy and DJ/GC-antagonism treatment groups were performed on OneArray platform, followed by differentially expressed genes (DEGs) screening. DEGs between Mod and Con groups were considered as HCC ascites-related genes, and those among different drug treatment and Mod groups were identified as DJ/GC-combination-related genes. Then, an interaction network of HCC ascites-related gene-DJ/GC combination-related gene-known therapeutic target gene for ascites was constructed. Based on nodes’ degree, closeness, betweenness and k-coreness, the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 axis with highly network topological importance was demonstrated to be a candidate target of DJ/GC combination acting on HCC ascites. Importantly, both qPCR and western blot analyses verified this regulatory effects based on HCC ascites mice in vivo and M-1 collecting duct cells in vitro. Collectively, different combination designs of DJ and GC may lead to synergistic or antagonistic effects on HCC ascites partially via regulating the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 axis, implying that global gene expression profiling combined with network analysis can offer an effective way to understand pharmacological mechanisms of traditional Chinese medicine prescriptions. PMID:28165501

  11. Therapeutic effects of Euphorbia Pekinensis and Glycyrrhiza glabra on Hepatocellular Carcinoma Ascites Partially Via Regulating the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 Signal Axis

    NASA Astrophysics Data System (ADS)

    Zhang, Yanqiong; Yan, Chen; Li, Yuting; Mao, Xia; Tao, Weiwei; Tang, Yuping; Lin, Ya; Guo, Qiuyan; Duan, Jingao; Lin, Na

    2017-02-01

    To clarify unknown rationalities of herbaceous compatibility of Euphorbia Pekinensis (DJ) and Glycyrrhiza glabra (GC) acting on hepatocellular carcinoma (HCC) ascites, peritoneum transcriptomics profiling of 15 subjects, including normal control (Con), HCC ascites mouse model (Mod), DJ-alone, DJ/GC-synergy and DJ/GC-antagonism treatment groups were performed on OneArray platform, followed by differentially expressed genes (DEGs) screening. DEGs between Mod and Con groups were considered as HCC ascites-related genes, and those among different drug treatment and Mod groups were identified as DJ/GC-combination-related genes. Then, an interaction network of HCC ascites-related gene-DJ/GC combination-related gene-known therapeutic target gene for ascites was constructed. Based on nodes’ degree, closeness, betweenness and k-coreness, the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 axis with highly network topological importance was demonstrated to be a candidate target of DJ/GC combination acting on HCC ascites. Importantly, both qPCR and western blot analyses verified this regulatory effects based on HCC ascites mice in vivo and M-1 collecting duct cells in vitro. Collectively, different combination designs of DJ and GC may lead to synergistic or antagonistic effects on HCC ascites partially via regulating the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 axis, implying that global gene expression profiling combined with network analysis can offer an effective way to understand pharmacological mechanisms of traditional Chinese medicine prescriptions.

  12. Therapeutic effects of Euphorbia Pekinensis and Glycyrrhiza glabra on Hepatocellular Carcinoma Ascites Partially Via Regulating the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 Signal Axis.

    PubMed

    Zhang, Yanqiong; Yan, Chen; Li, Yuting; Mao, Xia; Tao, Weiwei; Tang, Yuping; Lin, Ya; Guo, Qiuyan; Duan, Jingao; Lin, Na

    2017-02-06

    To clarify unknown rationalities of herbaceous compatibility of Euphorbia Pekinensis (DJ) and Glycyrrhiza glabra (GC) acting on hepatocellular carcinoma (HCC) ascites, peritoneum transcriptomics profiling of 15 subjects, including normal control (Con), HCC ascites mouse model (Mod), DJ-alone, DJ/GC-synergy and DJ/GC-antagonism treatment groups were performed on OneArray platform, followed by differentially expressed genes (DEGs) screening. DEGs between Mod and Con groups were considered as HCC ascites-related genes, and those among different drug treatment and Mod groups were identified as DJ/GC-combination-related genes. Then, an interaction network of HCC ascites-related gene-DJ/GC combination-related gene-known therapeutic target gene for ascites was constructed. Based on nodes' degree, closeness, betweenness and k-coreness, the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 axis with highly network topological importance was demonstrated to be a candidate target of DJ/GC combination acting on HCC ascites. Importantly, both qPCR and western blot analyses verified this regulatory effects based on HCC ascites mice in vivo and M-1 collecting duct cells in vitro. Collectively, different combination designs of DJ and GC may lead to synergistic or antagonistic effects on HCC ascites partially via regulating the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 axis, implying that global gene expression profiling combined with network analysis can offer an effective way to understand pharmacological mechanisms of traditional Chinese medicine prescriptions.

  13. Influence of ammonium availability on expression of nifD and amtB genes during biostimulation of a U(VI) contaminated aquifer: implications for U(VI) removal and monitoring the metabolic state of Geobacteraceae

    SciTech Connect

    Mouser, Paula J.; N'Guessan, A. Lucie; Elifantz, Hila; Holmes, Dawn E.; Williams, Kenneth H; Wilkins, Michael J.; Long, Philip E.; Lovley, Derek R.

    2009-03-25

    The influence of ammonium availability on bacterial community structure and the physiological status of Geobacter species during in situ bioremediation of uranium-contaminated groundwater was evaluated. Ammonium concentrations varied by 2 orders of magnitude (<4 to 400 ?M) across the study site. Analysis of 16S rRNA sequences suggested that ammonium may have been one factor influencing the community composition prior to acetate amendment with Rhodoferax species predominating over Geobacter species with higher ammonium and Dechloromonas species dominating at the site with lowest ammonium. However, once acetate was added and dissimilatory metal reduction was stimulated, Geobacter species became the predominant organisms at all locations. Rates of U(VI) reduction appeared to be more related to acetate concentrations rather than ammonium levels. In situ mRNA transcript abundance of the nitrogen fixation gene, nifD, and the ammonium transporter gene, amtB, in Geobacter species indicated that ammonium was the primary source of nitrogen during uranium reduction. The abundance of amtB was inversely correlated to ammonium levels, whereas nifD transcript levels were similar across all sites examined. These results suggest that nifD and amtB expression are closely regulated in response to ammonium availability to ensure an adequate supply of nitrogen while conserving cell resources. Thus, quantifying nifD and amtB transcript expression appears to be a useful approach for monitoring the nitrogen-related physiological status of subsurface Geobacter species. This study also emphasizes the need for more detailed analysis of geochemical and physiological interactions at the field scale in order to adequately model subsurface microbial processes during bioremediation.

  14. Distinct roles of P(II)-like signal transmitter proteins and amtB in regulation of nif gene expression, nitrogenase activity, and posttranslational modification of NifH in Azoarcus sp. strain BH72.

    PubMed

    Martin, Dietmar E; Reinhold-Hurek, Barbara

    2002-04-01

    P(II)-like signal transmitter proteins, found in Bacteria, Archaea, and plants, are known to mediate control of carbon and nitrogen assimilation. They indirectly regulate the activity of key metabolic enzymes and transcription factors by protein-protein interactions with signal transduction proteins. Many Proteobacteria harbor two paralogous P(II)-like proteins, GlnB and GlnK, whereas a novel third P(II) paralogue (GlnY) was recently identified in Azoarcus sp. strain BH72, a diazotrophic endophyte of grasses. In the present study, evidence was obtained that the P(II)-like proteins have distinct roles in mediating nitrogen and oxygen control of nif gene transcription and nitrogenase activity. Full repression of nif gene transcription in the presence of a combined nitrogen source or high oxygen concentrations was observed in wild-type and glnB and glnK knockout mutants, revealing that GlnB and GlnK can complement each other in mediating the repression. In contrast, in a glnBK double mutant strain in the presence of only GlnY, nif gene transcription was still detectable, albeit at a lower level, on nitrate or 20% oxygen. As another level of control, nitrogenase activity was regulated by at least three types of mechanisms in strain BH72: covalent modification of dinitrogenase reductase (NifH), probably by ADP-ribosylation, and two other, unknown means. Functional inactivation upon ammonium addition (switch-off) required the putative high-affinity ammonium transporter AmtB and GlnK, but not GlnB or GlnY. Functional inactivation in response to anaerobiosis did not depend on AmtB, GlnK, or GlnB. In contrast, covalent modification of NifH required both GlnB and GlnK and AmtB as response to ammonium addition, whereas it required either GlnB or GlnK and not AmtB when cells were shifted to anaerobiosis. In a glnBK double mutant expressing only GlnY, NifH modification was completely abolished, further revealing functional differences between the three P(II) paralogues.

  15. Expression and Localization of Aquaporin 4 and Aquaporin 5 along the Large Intestine of Colostrum-Suckling Buffalo Calves.

    PubMed

    Pelagalli, A; Squillacioti, C; De Luca, A; Pero, M E; Vassalotti, G; Lombardi, P; Avallone, L; Mirabella, N

    2016-12-01

    Aquaporins (AQPs) are membrane channel proteins that play a role in regulating water permeability in many tissues. To date, seven isoforms of AQPs have been reported in the gastrointestinal tract in different mammalian species. In contrast, both tissue distribution and expression of AQPs are unknown in the buffalo. The purpose of this study was to investigate the expression of both AQP4 and AQP5 mRNAs and their relative proteins in the large intestinal tracts of buffalo calves after colostrum suckling using reverse transcriptase polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry. Our results revealed a diversified tissue AQP4 and AQP5 immunolocalization accompanied by their highest expression in the tissues of colostrum-suckling buffalo calves confirmed by Western blotting. In particular, AQP4 was distributed along the endothelium and enterocytes while AQP5 in the endocrine cells. These findings provide direct evidence for AQP4 and AQP5 expression in the large intestine, suggesting that different AQPs collaborate functionally and distinctively in water handling during intestinal development, especially during the first period after delivery.

  16. Expression and Distribution Pattern of Aquaporin 4, 5 and 11 in Retinas of 15 Different Species

    PubMed Central

    Amann, Barbara; Kleinwort, Kristina J. H.; Hirmer, Sieglinde; Sekundo, Walter; Kremmer, Elisabeth; Hauck, Stefanie M.; Deeg, Cornelia A.

    2016-01-01

    Aquaporins (AQPs) are small integral membrane proteins with 13 members in mammals and are essential for water transport across membranes. They are found in many different tissues and cells. Currently, there are conflicting results regarding retinal aquaporin expression and subcellular localization between genome and protein analyses and among various species. AQP4, 7, 9 and 11 were described in the retina of men; whereas AQP6, 8 and 10 were earlier identified in rat retinas and AQP4, 5 and 11 in horses. Since there is a lack of knowledge regarding AQP expression on protein level in retinas of different animal models, we decided to analyze retinal cellular expression of AQP4, 5 and 11 in situ with immunohistochemistry. AQP4 was detected in all 15 explored species, AQP5 and AQP11 in 14 out of 15. Interestingly, AQP4 was unambiguously expressed in Muller glial cells, whereas AQP5 was differentially allocated among the species analyzed. AQP11 expression was Muller glial cell-specific in 50% of the animals, whereas in the others, AQP11 was detected in ganglion cell layer and at photoreceptor outer segments. Our data indicate a disparity in aquaporin distribution in retinas of various animals, especially for AQP5 and 11. PMID:27438827

  17. Effects of estradiol on ischemic factor-induced astrocyte swelling and AQP4 protein abundance.

    PubMed

    Rutkowsky, Jennifer M; Wallace, Breanna K; Wise, Phyllis M; O'Donnell, Martha E

    2011-07-01

    In the early hours of ischemic stroke, cerebral edema forms as Na, Cl, and water are secreted across the blood-brain barrier (BBB) and astrocytes swell. We have shown previously that ischemic factors, including hypoxia, aglycemia, and arginine vasopressin (AVP), stimulate BBB Na-K-Cl cotransporter (NKCC) and Na/H exchanger (NHE) activities and that inhibiting NKCC and/or NHE by intravenous bumetanide and/or HOE-642 reduces edema and infarct in a rat model of ischemic stroke. Estradiol also reduces edema and infarct in this model and abolishes ischemic factor stimulation of BBB NKCC and NHE. There is evidence that NKCC and NHE also participate in ischemia-induced swelling of astrocytes. However, little is known about estradiol effects on astrocyte cell volume. In this study, we evaluated the effects of AVP (100 nM), hypoxia (7.5% O(2)), aglycemia, hypoxia (2%)/aglycemia [oxygen glucose deprivation (OGD)], and estradiol (1-100 nM) on astrocyte cell volume using 3-O-methyl-d-[(3)H]glucose equilibration methods. We found that AVP, hypoxia, aglycemia, and OGD (30 min to 5 h) each significantly increased astrocyte cell volume, and that estradiol (30-180 min) abolished swelling induced by AVP or hypoxia, but not by aglycemia or OGD. Bumetanide and/or HOE-642 also abolished swelling induced by AVP but not aglycemia. Abundance of aquaporin-4, known to participate in ischemia-induced astrocyte swelling, was significantly reduced following 7-day but not 2- or 3-h estradiol exposures. Our findings suggest that hypoxia, aglycemia, and AVP each contribute to ischemia-induced astrocyte swelling, and that the edema-attenuating effects of estradiol include reduction of hypoxia- and AVP-induced astrocyte swelling and also reduction of aquaporin-4 abundance.

  18. The Neuroepithelium Disruption Could Generate Autoantibodies against AQP4 and Cause Neuromyelitis Optica and Hydrocephalus

    PubMed Central

    Castañeyra-Ruiz, Leandro; González-Marrero, Ibrahim; Castañeyra-Ruiz, Agustín; González-Toledo, Juan M.; Castañeyra-Ruiz, María; Perez-Molto, Francisco J.; Carmona-Calero, Emilia M.; Castañeyra-Perdomo, Agustín

    2014-01-01

    Neuromyelitis optica is an inflammatory disease characterized by neuritis and myelitis of the optic nerve. Its physiopathology is connected with the aquaporin-4 water channel, since antibodies against aquaporin-4 have been found in the cerebrospinal fluid and blood of neuromyelitis optica patients. The seropositivity for aquaporin-4 antibodies is used for the diagnosis of neuromyelitis optica or neuromyelitis optica spectrum disease. On the other hand, aquaporin-4 is expressed in astrocyte feet in the brain-blood barrier and subventricular zones of the brain ventricles. Aquaporin-4 expression is high in cerebrospinal fluid in hydrocephalus. Furthermore, neuroepithelial denudation precedes noncommunicating hydrocephalus and this neuroepithelial disruption could allow aquaporin-4 to reach anomalous brain areas where it is unrecognized and induce the generation of aquaporin-4 antibodies which could cause the neuromyelitis optica and certain types of hydrocephalus. PMID:27379319

  19. Identification and Expression Analysis of Aquaporins in the Potato Psyllid, Bactericera cockerelli

    PubMed Central

    Ibanez, Freddy; Hancock, Joseph; Tamborindeguy, Cecilia

    2014-01-01

    Aquaporin (AQPs) proteins transport water and uncharged low molecular-weight solutes across biological membranes. Six to 8 AQP genes have been identified in many insect species, but presently only three aquaporins have been characterized in phloem feeding insects. The objective of this study was to identify candidate AQPs in the potato psyllid, Bactericera cockerelli. Herein, we identified four candidate aquaporin cDNAs in B. cockerelli transcriptome. Phylogenetic analysis showed that candidate BcAQP2-like had high similarity to PRIP aquaporins; while candidates BcAQP4-like, BcAQP5-like and BcAQP9-like clustered within clade B. In particular, candidates BcAQP4-like and BcAQP5-like clustered with functionally validated insect aquaglyceroporin proteins. Expression analyses using RT-qPCR showed that all candidates were expressed in all life stages and tissues. Candidates BcAQP4-like and BcAQP5-like were highly expressed in bacteriocytes, while BcAQP9-like appeared to be expressed at high levels in whole body but not in the assayed tissues. This study is the first global attempt to identify putative aquaporins in a phloem feeding insect. PMID:25354208

  20. Effect of P2X7 Receptor Knockout on AQP-5 Expression of Type I Alveolar Epithelial Cells

    PubMed Central

    Ebeling, Georg; Bläsche, Robert; Hofmann, Falk; Augstein, Antje; Kasper, Michael; Barth, Kathrin

    2014-01-01

    P2X7 receptors, ATP-gated cation channels, are specifically expressed in alveolar epithelial cells. The pathophysiological function of this lung cell type, except a recently reported putative involvement in surfactant secretion, is unknown. In addition, P2X7 receptor-deficient mice show reduced inflammation and lung fibrosis after exposure with bleomycin. To elucidate the role of the P2X7 receptor in alveolar epithelial type I cells we characterized the pulmonary phenotype of P2X7 receptor knockout mice by using immunohistochemistry, western blot analysis and real-time RT PCR. No pathomorphological signs of fibrosis were found. Results revealed, however, a remarkable loss of aquaporin-5 protein and mRNA in young knockout animals. Additional in vitro experiments with bleomycin treated precision cut lung slices showed a greater sensitivity of the P2X7 receptor knockout mice in terms of aquaporin-5 reduction as wild type animals. Finally, P2X7 receptor function was examined by using the alveolar epithelial cell lines E10 and MLE-12 for stimulation experiments with bleomycin. The in vitro activation of P2X7 receptor was connected with an increase of aquaporin-5, whereas the inhibition of the receptor with oxidized ATP resulted in down regulation of aquaporin-5. The early loss of aquaporin-5 which can be found in different pulmonary fibrosis models does not implicate a specific pathogenetic role during fibrogenesis. PMID:24941004

  1. Interleukin-13 interferes with CFTR and AQP5 expression and localization during human airway epithelial cell differentiation

    SciTech Connect

    Skowron-zwarg, Marie; Boland, Sonja; Caruso, Nathalie; Coraux, Christelle; Marano, Francelyne; Tournier, Frederic . E-mail: f-tournier@paris7.jussieu.fr

    2007-07-15

    Interleukin-13 (IL-13) is a central regulator of Th2-dominated respiratory disorders such as asthma. Lesions of the airway epithelial barrier frequently observed in chronic respiratory inflammatory diseases are repaired through proliferation, migration and differentiation of epithelial cells. Our work is focused on the effects of IL-13 in human cellular models of airway epithelial cell regeneration. We have previously shown that IL-13 altered epithelial cell polarity during mucociliary differentiation of human nasal epithelial cells. In particular, the cytokine inhibited ezrin expression and interfered with its apical localization during epithelial cell differentiation in vitro. Here we show that CFTR expression is enhanced in the presence of the cytokine, that two additional CFTR protein isoforms are expressed in IL-13-treated cells and that part of the protein is retained within the endoplasmic reticulum. We further show that aquaporin 5 expression, a water channel localized within the apical membrane of epithelial cells, is completely abolished in the presence of the cytokine. These results show that IL-13 interferes with ion and water channel expression and localization during epithelial regeneration and may thereby influence mucus composition and hydration.

  2. Morphology and Aquaporin Immunohistochemistry of the Uterine Tube of Saanen Goats (Capra hircus): Comparison Throughout the Reproductive Cycle.

    PubMed

    Arrighi, S; Bosi, G; Frattini, S; Coizet, B; Groppetti, D; Pecile, A

    2016-06-01

    The expression of six different aquaporins (AQP1, 2, 3, 4, 5 and 9), integral membrane water channels that facilitate bi-directional passive movement of water, was investigated by immunohistochemistry in the uterine tube of pre-pubertal and adult Saanen goats (Capra hircus), comparing the different phases of the oestrous cycle. Regional morphology and secretory processes were markedly different during the goat oestrous cycle. The tested AQP molecules showed different expression patterns in comparison with already studied species. AQP1-immunoreactivity was evidenced at the endothelium of blood vessels and in nerve fibres, regardless of the tubal tract and cycle period. AQP4-immunoreactivity was shown on the lateral plasmalemma in the basal third of the epithelial cells at infundibulum and ampulla level in the cycling goats, more evidently during follicular than during luteal phase. No AQP4-immunoreactivity was noticed at the level of the isthmus region, regardless of the cycle phase. AQP5-immunoreactivity, localized at the apical surface of epithelial cells, increased from pre-puberty to adulthood. Thereafter, AQP5-immunoreactivity was prominent during the follicular phase, when it strongly decorated the apical plasmalemma of all epithelial cells at ampullary level. During luteal phase, immunoreactivity was discontinuous, being weak to strong at the apex of the secretory cells protruding into the lumen. In the isthmus region, the strongest AQP5-immunoreactivity was seen during follicular phase, with a clear localization in the apical plasmalemma of all the epithelial cells and also on the lateral plasmalemma. AQP2, 3 and 9 were undetectable all along the goat uterine tube. Likely, a collaboration of different AQP molecules sustains the fluid production in the goat uterine tube. AQP1-mediated transudation from the blood capillaries, together with permeation of the epithelium by AQP4 in the basal rim of the epithelial cells and final intervening of apical AQP5, could

  3. Salinity responsive aquaporins in the anal papillae of the larval mosquito, Aedes aegypti.

    PubMed

    Akhter, Hina; Misyura, Lidiya; Bui, Phuong; Donini, Andrew

    2017-01-01

    The larvae of the mosquito, Aedes aegypti normally inhabit freshwater (FW) where they face dilution of body fluids by osmotic influx of water. In response, the physiological actions of the anal papillae result in ion uptake while the Malpighian tubules and rectum work in concert to excrete excess water. In an apparent paradox, the anal papillae express aquaporins (AQPs) and are sites of water permeability which, if AQPs are expressed by the epithelium, apparently exaggerates the influx of water from their dilute environment. Recently, naturally breeding populations of A. aegypti were found in brackish water (BW), an environment which limits the osmotic gradient. Given that salinization of FW is an emerging environmental issue and that these larvae would presumably need to adjust to these changing conditions, this study investigates the expression of AQPs in the anal papillae and their response to rearing in hypo-osmotic and near isosmotic conditions. Transcripts of all six Aedes AQP homologs were detectable in the anal papillae and the transcript abundance of three AQP homologs in the papillae was different between rearing conditions. Using custom made antibodies, expression of two of these AQP homologs (AQP4 and AQP5) was localized to the syncytial epithelium of the anal papillae. Furthermore, the changes in transcript abundance of these two AQPs between the rearing conditions, were manifested at the protein level. Results suggest that AQP4 and AQP5 play an important physiological role in larval responses to changes in environmental salinity.

  4. Altered aquaporin expression in glaucoma eyes.

    PubMed

    Tran, Thuy Linh; Bek, Toke; la Cour, Morten; Nielsen, Søren; Prause, Jan Ulrik; Hamann, Steffen; Heegaard, Steffen

    2014-09-01

    Aquaporins (AQP) are channels in the cell membrane that mainly facilitate a passive transport of water. In the eye, AQPs are expressed in the ciliary body and retina and may contribute to the pathogenesis of glaucoma and optic neuropathy. We investigated the expression of AQP1, AQP3, AQP4, AQP5, AQP7 and AQP9 in human glaucoma eyes compared with normal eyes. Nine glaucoma eyes were examined. Of these, three eyes were diagnosed with primary open angle glaucoma; three eyes had neovascular glaucoma; and three eyes had chronic angle-closure glaucoma. Six eyes with normal intraocular pressure and without glaucoma were used as control. Immunohistochemistry was performed using antibodies against AQP1, AQP3, AQP4, AQP5, AQP7 and AQP9. For each specimen, optical densities of immunoprecipitates were measured using Photoshop and the staining intensities were calculated. Immunostaining showed labelling of AQP7 and AQP9 in the nonpigmented ciliary epithelium and the staining intensities were significantly decreased in glaucoma eyes (p = 0.003; p = 0.018). AQP7 expression in the Müller cell endfeet was increased (p = 0.046), and AQP9 labelling of the retinal ganglion cells (RGC) showed decreased intensity (p = 0.037). No difference in AQP1, AQP4 and AQP9 expression was found in the optic nerve fibres. This study is the first investigating AQPs in human glaucoma eyes. We found a reduced expression of AQP9 in the retinal ganglion cells of glaucoma eyes. Glaucoma also induced increased AQP7 expression in the Müller cell endfeet. In the ciliary body of glaucoma eyes, the expression of AQP7 and AQP9 was reduced. Therefore, the expression of AQPs seems to play a role in glaucoma.

  5. Differential expression of inwardly rectifying K+ channels and aquaporins 4 and 5 in autoimmune uveitis indicates misbalance in Müller glial cell-dependent ion and water homeostasis.

    PubMed

    Eberhardt, Christina; Amann, Barbara; Feuchtinger, Annette; Hauck, Stefanie M; Deeg, Cornelia A

    2011-05-01

    Reactive gliosis is a well-established response to virtually every retinal disease. Autoimmune uveitis, a sight threatening disease, is characterized by recurrent relapses through autoaggressive T-cells. The purpose of this study was to assess retinal Müller glial cell function in equine recurrent uveitis (ERU), a spontaneous disease model resembling the human disease, by investigating membrane proteins implicated in ion and water homeostasis. We found that Kir2.1 was highly expressed in diseased retinas, whereas Kir4.1 was downregulated in comparison to controls. Distribution of Kir2.1 appeared Müller cell associated in controls, whereas staining of cell somata in the inner nuclear layer was observed in uveitis. In contrast to other subunits, Kir4.1 was evenly expressed along equine Müller cells, whereas in ERU, Kir4.1 almost disappeared from Müller cells. Hence, we suggest a different mechanism for potassium buffering in the avascular equine retina and, moreover, an impairment in uveitis. Uveitic retinas showed significantly increased expression of AQP4 as well as a displaced expression from Müller cells in healthy specimens to an intense circular expression pattern in the outer nuclear layer in ERU cases. Most interestingly, we detected the aquaporin family member protein AQP5 to be expressed in Müller cells with strong enrichments in Müller cell secondary processes. This finding indicates that fluid regulation within the equine retina may be achieved by an additional aquaporin. Furthermore, AQP5 was significantly decreased in uveitis. We conclude that the Müller cell response in autoimmune uveitis implies considerable changes in its potassium and water physiology.

  6. Effects of the fusion design and immunization route on the immunogenicity of Ag85A-Mtb32 in adenoviral vectored tuberculosis vaccine

    PubMed Central

    Zhang, Yiling; Feng, Liqiang; Li, Liang; Wang, Dimin; Li, Chufang; Sun, Caijun; Li, Pingchao; Zheng, Xuehua; Liu, Yichu; Yang, Wei; Niu, Xuefeng; Zhong, Nanshan; Chen, Ling

    2015-01-01

    Vaccines containing multiple antigens may induce broader immune responses and provide better protection against Mycobacterium tuberculosis (Mtb) infection as compared to a single antigen. However, strategies for incorporating multiple antigens into a single vector and the immunization routes may affect their immunogenicity. In this study, we utilized recombinant adenovirus type 5 (rAd5) as a model vaccine vector, and Ag85A (Rv3804c) and Mtb32 (Rv0125) as model antigens, to comparatively evaluate the influence of codon usage optimization, signal sequence, fusion linkers, and immunization routes on the immunogenicity of tuberculosis (TB) vaccine containing multiple antigens in C57BL/6 mice. We showed that codon-optimized Ag85A and Mtb32 fused with a GSG linker induced the strongest systemic and pulmonary cell-mediated immune (CMI) responses. Strong CMI responses were characterized by the generation of a robust IFN-γ ELISPOT response as well as antigen-specific CD4+ T and CD8+ T cells, which secreted mono-, dual-, or multiple cytokines. We also found that subcutaneous (SC) and intranasal (IN)/oral immunization with this candidate vaccine exhibited the strongest boosting effects for Mycobacterium bovis bacille Calmette-Guérin (BCG)-primed systemic and pulmonary CMI responses, respectively. Our results supported that codon optimized Ag85A and Mtb32 fused with a proper linker and immunized through SC and IN/oral routes can generate the strongest systemic and pulmonary CMI responses in BCG-primed mice, which may be particularly important for the design of TB vaccines containing multiple antigens. PMID:26076321

  7. Effects of the fusion design and immunization route on the immunogenicity of Ag85A-Mtb32 in adenoviral vectored tuberculosis vaccine.

    PubMed

    Zhang, Yiling; Feng, Liqiang; Li, Liang; Wang, Dimin; Li, Chufang; Sun, Caijun; Li, Pingchao; Zheng, Xuehua; Liu, Yichu; Yang, Wei; Niu, Xuefeng; Zhong, Nanshan; Chen, Ling

    2015-01-01

    Vaccines containing multiple antigens may induce broader immune responses and provide better protection against Mycobacterium tuberculosis (Mtb) infection as compared to a single antigen. However, strategies for incorporating multiple antigens into a single vector and the immunization routes may affect their immunogenicity. In this study, we utilized recombinant adenovirus type 5 (rAd5) as a model vaccine vector, and Ag85A (Rv3804c) and Mtb32 (Rv0125) as model antigens, to comparatively evaluate the influence of codon usage optimization, signal sequence, fusion linkers, and immunization routes on the immunogenicity of tuberculosis (TB) vaccine containing multiple antigens in C57BL/6 mice. We showed that codon-optimized Ag85A and Mtb32 fused with a GSG linker induced the strongest systemic and pulmonary cell-mediated immune (CMI) responses. Strong CMI responses were characterized by the generation of a robust IFN-γ ELISPOT response as well as antigen-specific CD4(+) T and CD8(+) T cells, which secreted mono-, dual-, or multiple cytokines. We also found that subcutaneous (SC) and intranasal (IN)/oral immunization with this candidate vaccine exhibited the strongest boosting effects for Mycobacterium bovis bacille Calmette-Guérin (BCG)-primed systemic and pulmonary CMI responses, respectively. Our results supported that codon optimized Ag85A and Mtb32 fused with a proper linker and immunized through SC and IN/oral routes can generate the strongest systemic and pulmonary CMI responses in BCG-primed mice, which may be particularly important for the design of TB vaccines containing multiple antigens.

  8. Aquaporin water channels in the mammary gland: from physiology to pathophysiology and neoplasia.

    PubMed

    Mobasheri, Ali; Barrett-Jolley, Richard

    2014-03-01

    Aquaporins are membrane proteins that play fundamental roles in water and small solute transport across epithelial and endothelial barriers. Recent studies suggest that several aquaporin proteins are present in the mammary gland. Immunohistochemical techniques have confirmed the presence of aquaporin 1 (AQP1) and AQP3 water channels in rat, mouse, bovine and human mammary glands. Studies suggest that in addition to AQP1 and AQP3 AQP4, AQP5 and AQP7 proteins are expressed in different locations in the mammary gland. Aquaporins play key roles in tumor biology and are involved in cell growth, migration and formation of ascites via increased water permeability of micro-vessels. Emerging evidence suggests that expression of these proteins is altered in mammary tumors and in breast cancer cell lines although it is not yet clear whether this is a cause or a consequence of neoplastic development. This review analyzes the expression and potential functional roles of aquaporin water channels in the mammary gland. The physiological mechanisms involved in the transport of water and small solutes across mammary endothelial and epithelial barriers are discussed in the context of milk production and lactation. This paper also reviews papers from the recent cancer literature that implicate aquaporins in mammary neoplasia.

  9. Aquaporins in avian kidneys: function and perspectives.

    PubMed

    Nishimura, Hiroko; Yang, Yimu

    2013-12-01

    For terrestrial vertebrates, water economy is a prerequisite for survival, and the kidney is their major osmoregulatory organ. Birds are the only vertebrates other than mammals that can concentrate urine in adaptation to terrestrial environments. Aquaporin (AQP) and glyceroporin (GLP) are phylogenetically old molecules and have been found in plants, microbial organisms, invertebrates, and vertebrates. Currently, 13 AQPs/aquaGLPs and isoforms are known to be present in mammals. AQPs 1, 2, 3, 4, 6, 7, 8, and 11 are expressed in the kidney; of these, AQPs 1, 2, 3, 4, and 7 are shown to be involved in fluid homeostasis. In avian kidneys, AQPs 1, 2, 3, and 4 have been identified and characterized. Also, gene and/or amino acid sequences of AQP5, AQP7, AQP8, AQP9, AQP11, and AQP12 have been reported in birds. AQPs 2 and 3 are expressed along cortical and medullary collecting ducts (CDs) and are responsible, respectively, for the water inflow and outflow of CD epithelial cells. While AQP4 plays an important role in water exit in the CD of mammalian kidneys, it is unlikely to participate in water outflow in avian CDs. This review summarizes current knowledge on structure and function of avian AQPs and compares them to those in mammalian and nonmammalian vertebrates. Also, we aim to provide input into, and perspectives on, the role of renal AQPs in body water homeostasis during ontogenic and phylogenetic advancement.

  10. A novel human aquaporin-4 splice variant exhibits a dominant-negative activity: a new mechanism to regulate water permeability.

    PubMed

    De Bellis, Manuela; Pisani, Francesco; Mola, Maria Grazia; Basco, Davide; Catalano, Francesco; Nicchia, Grazia Paola; Svelto, Maria; Frigeri, Antonio

    2014-02-01

    Two major isoforms of aquaporin-4 (AQP4) have been described in human tissue. Here we report the identification and functional analysis of an alternatively spliced transcript of human AQP4, AQP4-Δ4, that lacks exon 4. In transfected cells AQP4-Δ4 is mainly retained in the endoplasmic reticulum and shows no water transport properties. When AQP4-Δ4 is transfected into cells stably expressing functional AQP4, the surface expression of the full-length protein is reduced. Furthermore, the water transport activity of the cotransfectants is diminished in comparison to transfectants expressing only AQP4. The observed down-regulation of both the expression and water channel activity of AQP4 is likely to originate from a dominant-negative effect caused by heterodimerization between AQP4 and AQP4-Δ4, which was detected in coimmunoprecipitation studies. In skeletal muscles, AQP4-Δ4 mRNA expression inversely correlates with the level of AQP4 protein and is physiologically associated with different types of skeletal muscles. The expression of AQP4-Δ4 may represent a new regulatory mechanism through which the cell-surface expression and therefore the activity of AQP4 can be physiologically modulated.

  11. A novel human aquaporin-4 splice variant exhibits a dominant-negative activity: a new mechanism to regulate water permeability

    PubMed Central

    De Bellis, Manuela; Pisani, Francesco; Mola, Maria Grazia; Basco, Davide; Catalano, Francesco; Nicchia, Grazia Paola; Svelto, Maria; Frigeri, Antonio

    2014-01-01

    Two major isoforms of aquaporin-4 (AQP4) have been described in human tissue. Here we report the identification and functional analysis of an alternatively spliced transcript of human AQP4, AQP4-Δ4, that lacks exon 4. In transfected cells AQP4-Δ4 is mainly retained in the endoplasmic reticulum and shows no water transport properties. When AQP4-Δ4 is transfected into cells stably expressing functional AQP4, the surface expression of the full-length protein is reduced. Furthermore, the water transport activity of the cotransfectants is diminished in comparison to transfectants expressing only AQP4. The observed down-regulation of both the expression and water channel activity of AQP4 is likely to originate from a dominant-negative effect caused by heterodimerization between AQP4 and AQP4-Δ4, which was detected in coimmunoprecipitation studies. In skeletal muscles, AQP4-Δ4 mRNA expression inversely correlates with the level of AQP4 protein and is physiologically associated with different types of skeletal muscles. The expression of AQP4-Δ4 may represent a new regulatory mechanism through which the cell-surface expression and therefore the activity of AQP4 can be physiologically modulated. PMID:24356448

  12. Superresolution Imaging of Aquaporin-4 Cluster Size in Antibody-Stained Paraffin Brain Sections.

    PubMed

    Smith, Alex J; Verkman, Alan S

    2015-12-15

    The water channel aquaporin-4 (AQP4) forms supramolecular clusters whose size is determined by the ratio of M1- and M23-AQP4 isoforms. In cultured astrocytes, differences in the subcellular localization and macromolecular interactions of small and large AQP4 clusters results in distinct physiological roles for M1- and M23-AQP4. Here, we developed quantitative superresolution optical imaging methodology to measure AQP4 cluster size in antibody-stained paraffin sections of mouse cerebral cortex and spinal cord, human postmortem brain, and glioma biopsy specimens. This methodology was used to demonstrate that large AQP4 clusters are formed in AQP4(-/-) astrocytes transfected with only M23-AQP4, but not in those expressing only M1-AQP4, both in vitro and in vivo. Native AQP4 in mouse cortex, where both isoforms are expressed, was enriched in astrocyte foot-processes adjacent to microcapillaries; clusters in perivascular regions of the cortex were larger than in parenchymal regions, demonstrating size-dependent subcellular segregation of AQP4 clusters. Two-color superresolution imaging demonstrated colocalization of Kir4.1 with AQP4 clusters in perivascular areas but not in parenchyma. Surprisingly, the subcellular distribution of AQP4 clusters was different between gray and white matter astrocytes in spinal cord, demonstrating regional specificity in cluster polarization. Changes in AQP4 subcellular distribution are associated with several neurological diseases and we demonstrate that AQP4 clustering was preserved in a postmortem human cortical brain tissue specimen, but that AQP4 was not substantially clustered in a human glioblastoma specimen despite high-level expression. Our results demonstrate the utility of superresolution optical imaging for measuring the size of AQP4 supramolecular clusters in paraffin sections of brain tissue and support AQP4 cluster size as a primary determinant of its subcellular distribution.

  13. Superresolution Imaging of Aquaporin-4 Cluster Size in Antibody-Stained Paraffin Brain Sections

    PubMed Central

    Smith, Alex J.; Verkman, Alan S.

    2015-01-01

    The water channel aquaporin-4 (AQP4) forms supramolecular clusters whose size is determined by the ratio of M1- and M23-AQP4 isoforms. In cultured astrocytes, differences in the subcellular localization and macromolecular interactions of small and large AQP4 clusters results in distinct physiological roles for M1- and M23-AQP4. Here, we developed quantitative superresolution optical imaging methodology to measure AQP4 cluster size in antibody-stained paraffin sections of mouse cerebral cortex and spinal cord, human postmortem brain, and glioma biopsy specimens. This methodology was used to demonstrate that large AQP4 clusters are formed in AQP4−/− astrocytes transfected with only M23-AQP4, but not in those expressing only M1-AQP4, both in vitro and in vivo. Native AQP4 in mouse cortex, where both isoforms are expressed, was enriched in astrocyte foot-processes adjacent to microcapillaries; clusters in perivascular regions of the cortex were larger than in parenchymal regions, demonstrating size-dependent subcellular segregation of AQP4 clusters. Two-color superresolution imaging demonstrated colocalization of Kir4.1 with AQP4 clusters in perivascular areas but not in parenchyma. Surprisingly, the subcellular distribution of AQP4 clusters was different between gray and white matter astrocytes in spinal cord, demonstrating regional specificity in cluster polarization. Changes in AQP4 subcellular distribution are associated with several neurological diseases and we demonstrate that AQP4 clustering was preserved in a postmortem human cortical brain tissue specimen, but that AQP4 was not substantially clustered in a human glioblastoma specimen despite high-level expression. Our results demonstrate the utility of superresolution optical imaging for measuring the size of AQP4 supramolecular clusters in paraffin sections of brain tissue and support AQP4 cluster size as a primary determinant of its subcellular distribution. PMID:26682810

  14. Role of the H-bond between L53 and T56 for Aquaporin-4 epitope in Neuromyelitis Optica.

    PubMed

    Pisani, Francesco; Simone, Laura; Gargano, Concetta Domenica; De Bellis, Manuela; Cibelli, Antonio; Mola, Maria Grazia; Catacchio, Giacomo; Frigeri, Antonio; Svelto, Maria; Nicchia, Grazia Paola

    2017-03-01

    Aquaporin-4 (AQP4) is the CNS water channel organized into well-ordered protein aggregates called Orthogonal Arrays of Particles (OAPs). Neuromyelitis Optica (NMO) is an autoimmune disease caused by anti-OAP autoantibodies (AQP4-IgG). Molecular Dynamics (MD) simulations have identified an H-bond between L53 and T56 as the key for AQP4 epitope and therefore of potential interest for drug design in NMO field. In the present study, we have experimentally tested this MD-prediction using the classic mutagenesis approach. We substituted T56 with V56 and tested this mutant for AQP4 aggregates and AQP4-IgG binding. gSTED super-resolution microscopy showed that the mutation does not affect AQP4 aggregate dimension; immunofluorescence and cytofluorimetric analysis demonstrated its unaltered AQP4-IgG binding, therefore invalidating the MD-prediction. We later investigated whether AQP4, expressed in Sf9 insect and HEK-293F cells, is able to correctly aggregate before and after the purification steps usually applied to obtain AQP4 crystal. The results demonstrated that AQP4-IgG recognizes AQP4 expressed in Sf9 and HEK-293F cells by immunofluorescence even though BN-PAGE analysis showed that AQP4 forms smaller aggregates when expressed in insect cells compared to mammalian cell lines. Notably, after AQP4 purification, from both insect and HEK-293F cells, no aggregates are detectable by BN-PAGE and AQP4-IgG binding is impaired in sandwich ELISA assays. All together these results indicate that 1) the MD prediction under analysis is not supported by experimental data and 2) the procedure to obtain AQP4 crystals might affect its native architecture and, as a consequence, MD simulations. In conclusion, given the complex nature of the AQP4 epitope, MD might not be the suitable for molecular medicine advances in NMO.

  15. Cloning and characterization of a zebrafish homologue of human AQP1: a bifunctional water and gas channel

    PubMed Central

    Chen, Li-Ming; Zhao, Jinhua; Musa-Aziz, Raif; Pelletier, Marc F.; Drummond, Iain A.

    2010-01-01

    The mammalian aquaporins AQP1, AQP4, and AQP5 have been shown to function not only as water channels but also as gas channels. Zebrafish have two genes encoding an AQP1 homologue, aqp1a and aqp1b. In the present study, we cloned the cDNA that encodes the zebrafish protein Aqp1a from the 72-h postfertilization (hpf) embryo of Danio rerio, as well as from the swim bladder of the adult. The deduced amino-acid sequence of aqp1a consists of 260 amino acids and is 59% identical to human AQP1. By analyzing the genomic DNA sequence, we identified four exons in the aqp1a gene. By in situ hybridization, aqp1a is expressed transiently in the developing vasculature and in erythrocytes from 16 to 48 h of development. Later, at 72 hpf, aqp1a is expressed in dermal ionocytes and in the swim bladder. Western blot analysis of adult tissues reveals that Aqp1a is most highly expressed in the eye and swim bladder. Xenopus oocytes expressing aqp1a have a channel-dependent (*) osmotic water permeability (Pf*) that is indistinguishable from that of human AQP1. On the basis of the magnitude of the transient change in surface pH (ΔpHS) that were recorded as the oocytes were exposed to either CO2 or NH3, we conclude that zebrafish Aqp1a is permeable to both CO2 and NH3. The ratio (ΔpHS*)CO2/Pf* is about half that of human AQP1, and the ratio (ΔpHS*)NH3/Pf* is about one-quarter that of human AQP1. Thus, compared with human AQP1, zebrafish Aqp1a has about twice the selectivity for CO2 over NH3. PMID:20739606

  16. AMPK/α-Ketoglutarate Axis Regulates Intestinal Water and Ion Homeostasis in Young Pigs.

    PubMed

    He, Liuqin; Huang, Niu; Li, Huan; Tian, Junquan; Zhou, Xihong; Li, Tiejun; Yao, Kang; Wu, Guoyao; Yin, Yulong

    2017-03-22

    Water and ion absorption via sensitive aquaporins (AQPs) and ion channels is of critical importance in intestinal health. However, whether α-ketoglutarate (AKG) could improve intestinal water and ion homeostasis in lipopolysaccharide (LPS)-challenged piglets and whether the AMP-activated protein kinase (AMPK) pathway is involved remains largely unknown. This study was conducted to investigate the effect of dietary AKG supplementation on the small intestinal water and ion homeostasis through modulating the AMPK pathway in a piglet diarrhea model. A total of 32 weaned piglets were used in a 2 × 2 factorial design; the major factors were diet (basal diet or 1% AKG diet) and challenge (Escherichia coli LPS or saline). The results showed that LPS challenge increased the diarrhea index and affected the concentrations of serum Na(+), K(+), Cl(-), glucose, and AKG and its metabolites in piglets fed the basal or AKG diet. However, the addition of AKG attenuated diarrhea incidence and reversed these serum parameter concentrations. Most AQPs (e.g., AQP1, AQP3, AQP4, AQP5, AQP8, AQP10, and AQP11) and ion transporters (NHE3, ENaC, and DRA/PAT1) were widely distributed in the duodenum and jejunum of piglets. We also found that AKG up-regulated the expression of intestinal epithelial AQPs while inhibiting the expression of ion transporters. LPS challenge decreased (P < 0.05) the gene and protein expression of the AMPK pathway (AMPKα1, AMPKα2, SIRT1, PGC-1α, ACC, and TORC2) in the jejunum and ileum. Notably, AKG supplementation enhanced the abundance of these proteins in the LPS-challenged piglets. Collectively, AKG plays an important role in increasing water and ion homeostasis through modulating the AMPK pathway. Our novel finding has important implications for the prevention and treatment of gut dysfunction in neonates.

  17. Expression of the Astrocyte Water Channel Aquaporin-4 in the Mouse Brain.

    PubMed

    Hubbard, Jacqueline A; Hsu, Mike S; Seldin, Marcus M; Binder, Devin K

    2015-01-01

    Aquaporin-4 (AQP4) is a bidirectional water channel that is found on astrocytes throughout the central nervous system. Expression is particularly high around areas in contact with cerebrospinal fluid, suggesting that AQP4 plays a role in fluid exchange between the cerebrospinal fluid compartments and the brain. Despite its significant role in the brain, the overall spatial and region-specific distribution of AQP4 has yet to be fully characterized. In this study, we used Western blotting and immunohistochemical techniques to characterize AQP4 expression and localization throughout the mouse brain. We observed AQP4 expression throughout the forebrain, subcortical areas, and brainstem. AQP4 protein levels were highest in the cerebellum with lower expression in the cortex and hippocampus. We found that AQP4 immunoreactivity was profuse on glial cells bordering ventricles, blood vessels, and subarachnoid space. Throughout the brain, AQP4 was expressed on astrocytic end-feet surrounding blood vessels but was also heterogeneously expressed in brain tissue parenchyma and neuropil, often with striking laminar specificity. In the cerebellum, we showed that AQP4 colocalized with the proteoglycan brevican, which is synthesized by and expressed on cerebellar astrocytes. Despite the high abundance of AQP4 in the cerebellum, its functional significance has yet to be investigated. Given the known role of AQP4 in synaptic plasticity in the hippocampus, the widespread and region-specific expression pattern of AQP4 suggests involvement not only in fluid balance and ion homeostasis but also local synaptic plasticity and function in distinct brain circuits.

  18. Protein kinase A-regulated membrane trafficking of a green fluorescent protein-aquaporin 5 chimera in MDCK cells.

    PubMed

    Kosugi-Tanaka, Chisato; Li, Xuefei; Yao, Chenjuan; Akamatsu, Tetsuya; Kanamori, Norio; Hosoi, Kazuo

    2006-04-01

    The green fluorescent protein (GFP) of the jellyfish, Aeqorea victoria, was used as an autofluorescent tag to track the trafficking of aquaporin 5 (AQP5), an exocrine gland-type water channel. Two groups of chimeric proteins were constructed; one in which GFP was fused to the amino-terminus of AQP5 (GFP-AQP5) and the other, in which it was fused to the carboxyl terminus of it (AQP5-GFP). In each group, 2 chimeras were produced, a wild-type AQP5 with its normal sequence and a mutant AQP5 having a mutated amino acid at 259, i.e., GFP-AQP5-T259A and AQP5-GFP-T259A. They were used to transfect Madin-Darby canine kidney (MDCK) cells. The GFP-AQP5 chimera was localized in the intracellular vesicles, which trafficked to the plasma membrane in response to N(6), 2'-O-dibutyryladenosine 3', 5'-cyclic monophosphate (dbcAMP). Membrane trafficking was inhibited by N-[2-(p-bromocinnamylamino)ethyl]-5-isoquimolinesulfonamide (H-89) but not by palmitoyl-dl-carnitine chloride (PCC). In contrast, the AQP5-GFP chimera expressed in MDCK cells was localized constitutively on the plasma membrane. The cellular localization of the latter chimera was not affected by stimulation with dbcAMP in the presence or absence of H-89 or PCC. Replacement of Thr-259 with Ala-259 did not affect the dbcAMP-induced translocation of the chimeric protein, suggesting that phosphorylation of Thr-259 was not necessary for AQP5 trafficking under the present experimental conditions. Thus, the GFP-AQP5 chimera will be a useful tool to study AQP5 trafficking in vitro, whereas the constitutive membrane localization of the AQP5-GFP chimera suggests the importance of the carboxyl terminus of the AQP5 protein for its sorting, whether it is translocated to intracellular vesicles or to the plasma membrane.

  19. Characterization of Aquaporin 4 Protein Expression and Localization in Tissues of the Dogfish (Squalus acanthias).

    PubMed

    Cutler, Christopher P; Harmon, Sheena; Walsh, Jonathon; Burch, Kia

    2012-01-01

    The role of aquaporin water channels such as aquaporin 4 (Aqp4) in elasmobranchs such as the dogfish Squalus acanthias is completely unknown. This investigation set out to determine the expression and cellular and sub-cellular localization of Aqp4 protein in dogfish tissues. Two polyclonal antibodies were generated (AQP4/1 and AQP4/2) and these showed somewhat different characteristics in Western blotting and immunohistochemistry. Western blots using the AQP4/1 antibody showed two bands (35.5 and 49.5 kDa) in most tissues in a similar fashion to mammals. Liver had an additional band of 57 kDa and rectal gland two further faint bands of 37.5 and 38.5 kDa. However, unlike in mammals, Aqp4 protein was ubiquitously expressed in all tissues including gill and liver. The AQP4/2 antibody appeared much less specific in Western blots. Both antibodies were used in immunohistochemistry and showed similar cellular localizations, although the AQP4/2 antibody had a more restricted sub-cellular distribution compared to AQP4/1 and therefore appeared to be more specific for Aqp4. In kidney a sub-set of tubules were stained which may represent intermediate tubule segments (In-III-In-VI). AQP4/1 and AQP4/2 antibodies localized to the same tubules segments in serial sections although the intensity and sub-cellular distribution were different. AQP4/2 showed a basal or basolateral membrane distribution whereas AQP4/1 was often distributed throughout the whole cell including the nuclear region. In rectal gland and cardiac stomach Aqp4 was localized to secretory tubules but again AQP/1 and AQP/2 exhibited different sub-cellular distributions. In gill, both antibodies stained large cells in the primary filament and secondary lamellae. Again AQP4/1 antibody stained most or all the cell including the nucleus, whereas AQP4/2 had a plasma membrane or plasma membrane and cytoplasmic distribution. Two types of large mitochondrial rich transport cells are known to exist in elasmobranchs

  20. Aquaporin-4 orthogonal arrays of particles are the target for neuromyelitis optica autoantibodies.

    PubMed

    Nicchia, Grazia Paola; Mastrototaro, Mauro; Rossi, Andrea; Pisani, Francesco; Tortorella, Carla; Ruggieri, Maddalena; Lia, Anna; Trojano, Maria; Frigeri, Antonio; Svelto, Maria

    2009-10-01

    Neuromyelitis optica (NMO) is an inflammatory autoimmune demyelinating disease of the central nervous system (CNS) which in autoantibodies produced by patients with NMO (NMO-IgG) recognize a glial water channel protein, Aquaporin-4 (AQP4) expressed as two major isoforms, M1- and M23-AQP4, in which the plasma membrane form orthogonal arrays of particles (OAPs). AQP4-M23 is the OAP-forming isoform, whereas AQP4-M1 alone is unable to form OAPs. The function of AQP4 organization into OAPs in normal physiology is unknown; however, alteration in OAP assemblies is reported for several CNS pathological states. In this study, we demonstrate that in the CNS, NMO-IgG is able to pull down both M1- and M23-AQP4 but experiments performed using cells selectively transfected with M1- or M23-AQP4 and native tissues show NMO-IgG epitope to be intrinsic in AQP4 assemblies into OAPs. Other OAP-forming water-channel proteins, such as the lens Aquaporin-0 and the insect Aquaporin-cic, were not recognized by NMO-IgG, indicating an epitope characteristic of AQP4-OAPs. Finally, water transport measurements show that NMO-IgG treatment does not significantly affect AQP4 function. In conclusion, our results suggest for the first time that OAP assemblies are required for NMO-IgG to recognize AQP4.

  1. Effects of Aquaporin 4 Knockdown on Brain Edema of the Uninjured Side After Traumatic Brain Injury in Rats

    PubMed Central

    Chen, Jian-Qiang; Zhang, Cheng-Cheng; Jiang, Sheng-Nan; Lu, Hong; Wang, Wei

    2016-01-01

    Background Traumatic brain injury (TBI) induces edema on the uninjured side (i.e., contralateral brain tissue; CBT). We evaluated the role of AQP4 in CBT edema formation following TBI. Material/Methods Mild or severe TBI was induced using a controlled cortical impact model in rats, immediately followed by intraventricular siRNA infusions. The effects of AQP4 siRNA on CBT edema were assessed at up to 168 h. Results Mild or severe TBI induced different patterns of CBT edema. Furthermore, following mild TBI, brain water content (BWC) was increased at 72 h thereafter and AQP4 expression was increased after 168 h, relative to non-injured rats (i.e., sham). AQP4 interference reduced AQP4 expression 48 h thereafter and BWC 72 h thereafter, relative to control siRNA. In contrast, following severe TBI, BWC was increased 1 h thereafter and AQP4 expression was transiently enhanced after 1 h, relative to sham. However, AQP4 interference reduced AQP4 expression after 1 h and BWC 24 h thereafter, relative to control siRNA. Finally, apparent diffusion coefficient (ADC) value in CBT was positively correlated with AQP4 expression level following severe, but not mild, TBI. AQP4 interference disrupted this correlation. Conclusions AQP4 interference reduces CBT edema formation, and ADC value may predict TBI severity. PMID:27930615

  2. The Role of Astrocytic Aquaporin-4 in Synaptic Plasticity and Learning and Memory

    PubMed Central

    Szu, Jenny I.; Binder, Devin K.

    2016-01-01

    Aquaporin-4 (AQP4) is the predominant water channel expressed by astrocytes in the central nervous system (CNS). AQP4 is widely expressed throughout the brain, especially at the blood-brain barrier where AQP4 is highly polarized to astrocytic foot processes in contact with blood vessels. The bidirectional water transport function of AQP4 suggests its role in cerebral water balance in the CNS. The regulation of AQP4 has been extensively investigated in various neuropathological conditions such as cerebral edema, epilepsy, and ischemia, however, the functional role of AQP4 in synaptic plasticity, learning, and memory is only beginning to be elucidated. In this review, we explore the current literature on AQP4 and its influence on long term potentiation (LTP) and long term depression (LTD) in the hippocampus as well as the potential relationship between AQP4 and in learning and memory. We begin by discussing recent in vitro and in vivo studies using AQP4-null and wild-type mice, in particular, the impairment of LTP and LTD observed in the hippocampus. Early evidence using AQP4-null mice have suggested that impaired LTP and LTD is brain-derived neurotrophic factor dependent. Others have indicated a possible link between defective LTP and the downregulation of glutamate transporter-1 which is rescued by chronic treatment of β-lactam antibiotic ceftriaxone. Furthermore, behavioral studies may shed some light into the functional role of AQP4 in learning and memory. AQP4-null mice performances utilizing Morris water maze, object placement tests, and contextual fear conditioning proposed a specific role of AQP4 in memory consolidation. All together, these studies highlight the potential influence AQP4 may have on long term synaptic plasticity and memory. PMID:26941623

  3. Aquaporin-4 expression is severely reduced in human sarcoglycanopathies and dysferlinopathies.

    PubMed

    Assereto, Stefania; Mastrototaro, Mauro; Stringara, Silvia; Gazzerro, Elisabetta; Broda, Paolo; Nicchia, Grazia Paola; Svelto, Maria; Bruno, Claudio; Nigro, Vincenzo; Lisanti, M P; Frigeri, Antonio; Minetti, Carlo

    2008-07-15

    Aquaporin-4 (AQP4) is the major water channel expressed in fast-twitch skeletal muscle fibers. AQP4 is reduced in Duchenne and Becker Muscular Dystrophies, but not in caveolinopathies, thus suggesting an interaction with dystrophin or with members of the dystrophin-glycoprotein complex (DGC) rather than a nonspecific effect due to muscle membrane damage. To establish the role of sarcoglycans in AQP4 decrease occurring in muscular dystrophy, AQP4 expression was analyzed in muscle biopsies from patients affected by Limb Girdle Muscular Dystrophies (LGMDs) 2C-F genetically confirmed. In all the LGMD 2C-F (2alpha-, 1beta-, 2gamma-, 1delta-deficiency), AQP4 was severely decreased. This effect was associated to a marked reduction in alpha1-syntrophin levels. In control muscle AQP4 did not show a direct interaction with any of the four sarcoglycans but, it co-immunoprecipitated with alpha1-syntrophin, indicating that this modular protein may link AQP4 levels with the DGC complex. To determine whether AQP4 expression could be affected in other LGMDs due to the defect of a membrane protein not associated to the dystrophin complex, we examined AQP4 expression in 6 patients affected by dysferlin deficiency genetically confirmed. All the patients displayed a reduction of the water channel, and AQP4 expression appeared to correlate with the severity of the muscle histopathological lesions. However, differently from what observed in the sarcoglycans, alpha1-syntrophin expression was normal or just slightly reduced. These results seem to indicate an additional mechanism of regulation of AQP4 levels in muscle cells. In accordance with a specific effect of membrane muscle disorders, AQP4 protein levels were not changed in 3 mitochondrial and 3 metabolic myopathies. In conclusion, AQP4 expression and membrane localization are markedly reduced in LGMD 2B-2F. The role of AQP4 in the degenerative mechanism occurring in these diseases will be the object of our future research.

  4. Acute and Chronic Changes in Aquaporin 4 Expression After Spinal Cord Injury

    PubMed Central

    Nesic, Olivera; Lee, Julieann; Ye, Zaiming; Unabia, Geda C.; Rafati, Danny; Hulsebosch, Claire E.; Perez-Polo, J. Regino

    2007-01-01

    The effect of spinal cord injury (SCI) on the expression levels and distribution of water channel aquaporin 4 (AQP4) has not been studied. We have found AQP4 in gray and white matter astrocytes in both uninjured and injured rat spinal cords. AQP4 was detected in astrocytic processes that were tightly surrounding neurons and blood vessels, but more robustly in glia limitans externa and interna, which were forming an interface between spinal cord parenchyma and cerebrospinal fluid (CSF). Such spatial distribution of AQP4 suggests a critical role that astrocytes expressing AQP4 play in the transport of water from blood/CSF to spinal cord parenchyma and vice versa. SCI induced biphasic changes in astrocytic AQP4 levels, including its early down-regulation and subsequent persistent up-regulation. However, changes in AQP4 expression did not correlate well with the onset and magnitude of astrocytic activation, when measured as changes in GFAP expression levels. It appears that reactive astrocytes began expressing increased levels of AQP4 after migrating to the wound area (thoracic region) two weeks after SCI, and AQP4 remained significantly elevated for months after SCI. We also showed that increased levels of AQP4 spread away from the lesion site to cervical and lumbar segments, but only in chronically injured spinal cords. Although overall AQP4 expression levels increased in chronically-injured spinal cords, AQP4 immunolabeling in astrocytic processes forming glia limitans externa was decreased, which may indicate impaired water transport through glia limitans externa. Finally, we also showed that SCI-induced changes in AQP4 protein levels correlate, both temporally and spatially, with persistent increases in water content in acutely and chronically injured spinal cords. Although correlative, this finding suggests a possible link between AQP4 and impaired water transport/edema/syringomyelia in contused spinal cords. PMID:17074445

  5. Aquaporin-4: orthogonal array assembly, CNS functions, and role in neuromyelitis optica

    PubMed Central

    Verkman, Alan S; Ratelade, Julien; Rossi, Andrea; Zhang, Hua; Tradtrantip, Lukmanee

    2011-01-01

    Aquaporin-4 (AQP4) is a water-selective transporter expressed in astrocytes throughout the central nervous system, as well as in kidney, lung, stomach and skeletal muscle. The two AQP4 isoforms produced by alternative spicing, M1 and M23 AQP4, form heterotetramers that assemble in cell plasma membranes in supramolecular structures called orthogonal arrays of particles (OAPs). Phenotype analysis of AQP4-null mice indicates the involvement of AQP4 in brain and spinal cord water balance, astrocyte migration, neural signal transduction and neuroinflammation. AQP4-null mice manifest reduced brain swelling in cytotoxic cerebral edema, but increased brain swelling in vasogenic edema and hydrocephalus. AQP4 deficiency also increases seizure duration, impairs glial scarring, and reduces the severity of autoimmune neuroinflammation. Each of these phenotypes is likely explicable on the basis of reduced astrocyte water permeability in AQP4 deficiency. AQP4 is also involved in the neuroinflammatory demyelinating disease neuromyelitis optica (NMO), where autoantibodies (NMO-IgG) targeting AQP4 produce astrocyte damage and inflammation. Mice administered NMO-IgG and human complement by intracerebral injection develop characteristic NMO lesions with neuroinflammation, demyelination, perivascular complement deposition and loss of glial fibrillary acidic protein and AQP4 immunoreactivity. Our findings suggest the potential utility of AQP4-based therapeutics, including small-molecule modulators of AQP4 water transport function for therapy of brain swelling, injury and epilepsy, as well as small-molecule or monoclonal antibody blockers of NMO-IgG binding to AQP4 for therapy of NMO. PMID:21552296

  6. Aquaporin-4 Regulates the Velocity and Frequency of Cortical Spreading Depression in Mice

    PubMed Central

    Yao, Xiaoming; Smith, Alex J.; Jin, Byung-Ju; Zador, Zsolt; Manley, Geoffrey T.; Verkman, A.S.

    2016-01-01

    The astrocyte water channel aquaporin-4 (AQP4) regulates extracellular space (ECS) K+ concentration ([K+]e) and volume dynamics following neuronal activation. Here, we investigated how AQP4-mediated changes in [K+]e and ECS volume affect the velocity, frequency and amplitude of cortical spreading depression (CSD) depolarizations produced by surface KCl application in wild-type (AQP4+/+) and AQP4-deficient (AQP4−/−) mice. Contrary to initial expectations, both the velocity and frequency of CSD were significantly reduced in AQP4−/− mice when compared to AQP4+/+ mice, by 22% and 32%, respectively. Measurement of [K+]e with K+-selective microelectrodes demonstrated an increase to ~35 mM during spreading depolarizations in both AQP4+/+ and AQP4−/− mice, but the rates of [K+]e increase (3.5 vs. 1.5 mM/s) and reuptake (t1/2 33 vs. 61 s) were significantly reduced in AQP4−/− mice. ECS volume fraction measured by trimethylammonium iontophoresis was greatly reduced during depolarizations from 0.18 to 0.053 in AQP4+/+ mice, and 0.23 to 0.063 in AQP4−/− mice. Analysis of the experimental data using a mathematical model of CSD propagation suggested that the reduced velocity of CSD depolarizations in AQP4−/− mice was primarily a consequence of the slowed increase in [K+]e during neuronal depolarization. These results demonstrate that AQP4 effects on [K+]e and ECS volume dynamics accelerate CSD propagation. PMID:25944186

  7. Tolerance checkpoint bypass permits emergence of pathogenic T cells to neuromyelitis optica autoantigen aquaporin-4

    PubMed Central

    Sagan, Sharon A.; Winger, Ryan C.; Cruz-Herranz, Andrés; Nelson, Patricia A.; Hagberg, Sarah; Miller, Corey N.; Spencer, Collin M.; Ho, Peggy P.; Bennett, Jeffrey L.; Levy, Michael; Levin, Marc H.; Verkman, Alan S.; Steinman, Lawrence; Green, Ari J.; Anderson, Mark S.; Sobel, Raymond A.; Zamvil, Scott S.

    2016-01-01

    Aquaporin-4 (AQP4)-specific T cells are expanded in neuromyelitis optica (NMO) patients and exhibit Th17 polarization. However, their pathogenic role in CNS autoimmune inflammatory disease is unclear. Although multiple AQP4 T-cell epitopes have been identified in WT C57BL/6 mice, we observed that neither immunization with those determinants nor transfer of donor T cells targeting them caused CNS autoimmune disease in recipient mice. In contrast, robust proliferation was observed following immunization of AQP4-deficient (AQP4−/−) mice with AQP4 peptide (p) 135–153 or p201–220, peptides predicted to contain I-Ab–restricted T-cell epitopes but not identified in WT mice. In comparison with WT mice, AQP4−/− mice used unique T-cell receptor repertoires for recognition of these two AQP4 epitopes. Donor T cells specific for either determinant from AQP4−/−, but not WT, mice induced paralysis in recipient WT and B-cell–deficient mice. AQP4-specific Th17-polarized cells induced more severe disease than Th1-polarized cells. Clinical signs were associated with opticospinal infiltrates of T cells and monocytes. Fluorescent-labeled donor T cells were detected in CNS lesions. Visual system involvement was evident by changes in optical coherence tomography. Fine mapping of AQP4 p201–220 and p135–153 epitopes identified peptides within p201–220 but not p135–153, which induced clinical disease in 40% of WT mice by direct immunization. Our results provide a foundation to evaluate how AQP4-specific T cells contribute to AQP4-targeted CNS autoimmunity (ATCA) and suggest that pathogenic AQP4-specific T-cell responses are normally restrained by central tolerance, which may be relevant to understanding development of AQP4-reactive T cells in NMO. PMID:27940915

  8. Aquaporin 5 Plays a Role in Estrogen-Induced Ectopic Implantation of Endometrial Stromal Cells in Endometriosis.

    PubMed

    Jiang, Xiu Xiu; Fei, Xiang Wei; Zhao, Li; Ye, Xiao Lei; Xin, Liao Bin; Qu, Yang; Xu, Kai Hong; Wu, Rui Jin; Lin, Jun

    2015-01-01

    Aquaporin 5 (AQP5) participates in the migration of endometrial cells. Elucidation of the molecular mechanisms associated with AQP5-mediated, migration of endometrial cells may contribute to a better understanding of endometriosis. Our objectives included identifying the estrogen-response element (ERE) in the promoter region of the AQP5 gene, and, investigating the effects of AQP5 on ectopic implantation of endometrial cells. Luciferase reporter assays and electrophoretic mobility shift assay (EMSA) identified the ERE-like motif in the promoter region of the AQP5 gene. After blocking and up-regulating estradiol (E2) levels, we analysed the expression of AQP5 in endometrial stromal (ES) cells. After blocking E2 /or phosphatidylinositol 3 kinase(PI3K), we analysed the role of AQP5 in signaling pathways. We constructed an AQP5, shRNA, lentiviral vector to knock out the AQP5 gene in ES cells. After knock-out of the AQP5 gene, we studied the role of AQP5 in cell invasion, proliferation, and the formation of ectopic endometrial implants in female mice. We identified an estrogen-response element in the promoter region of the AQP5 gene. Estradiol (E2) increased AQP5 expression in a dose-dependent fashion, that was blocked by ICI182,780(an estrogen receptor inhibitor). E2 activated PI3K /protein kinase B(AKT) pathway (PI3K/AKT), that, in turn, increased AQP5 expression. LY294002(PI3K inhibitor) attenuated estrogen-enhanced, AQP5 expression. Knock-out of the AQP5 gene with AQP5 shRNA lentiviral vector significantly inhibited E2-enhanced invasion, proliferation of ES cells and formation of ectopic implants. Estrogen induces AQP5 expression by activating ERE in the promoter region of the AQP5gene, activates the PI3K/AKT pathway, and, promotes endometrial cell invasion and proliferation. These results provide new insights into some of the mechanisms that may underpin the development of deposits of ectopic endometrium.

  9. Optic neuritis in neuromyelitis optica.

    PubMed

    Levin, Marc H; Bennett, Jeffrey L; Verkman, A S

    2013-09-01

    Neuromyelitis optica (NMO) is an autoimmune demyelinating disease associated with recurrent episodes of optic neuritis and transverse myelitis, often resulting in permanent blindness and/or paralysis. The discovery of autoantibodies (AQP4-IgG) that target aquaporin-4 (AQP4) has accelerated our understanding of the cellular mechanisms driving NMO pathogenesis. AQP4 is a bidirectional water channel expressed on the plasma membranes of astrocytes, retinal Müller cells, skeletal muscle, and some epithelial cells in kidney, lung and the gastrointestinal tract. AQP4 tetramers form regular supramolecular assemblies at the cell plasma membrane called orthogonal arrays of particles. The pathological features of NMO include perivascular deposition of immunoglobulin and activated complement, loss of astrocytic AQP4, inflammatory infiltration with granulocyte and macrophage accumulation, and demyelination with axon loss. Current evidence supports a causative role of AQP4-IgG in NMO, in which binding of AQP4-IgG to AQP4 orthogonal arrays on astrocytes initiates complement-dependent and antibody-dependent cell-mediated cytotoxicity and inflammation. Immunosuppression and plasma exchange are the mainstays of therapy for NMO optic neuritis. Novel therapeutics targeting specific steps in NMO pathogenesis are entering the development pipeline, including blockers of AQP4-IgG binding to AQP4 and inhibitors of granulocyte function. However, much work remains in understanding the unique susceptibility of the optic nerves in NMO, in developing animal models of NMO optic neuritis, and in improving therapies to preserve vision.

  10. OPTIC NEURITIS IN NEUROMYELITIS OPTICA

    PubMed Central

    Levin, Marc H.; Bennett, Jeffrey L.; Verkman, A.S.

    2013-01-01

    Neuromyelitis optica (NMO) is an autoimmune demyelinating disease associated with recurrent episodes of optic neuritis and transverse myelitis, often resulting in permanent blindness and/or paralysis. The discovery of autoantibodies (AQP4-IgG) that target aquaporin-4 (AQP4) has accelerated our understanding of the cellular mechanisms driving NMO pathogenesis. AQP4 is a bidirectional water channel expressed on the plasma membranes of astrocytes, retinal Müller cells, skeletal muscle, and some epithelial cells in kidney, lung and the gastrointestinal tract. AQP4 tetramers form regular supramolecular assemblies at the cell plasma membrane called orthogonal arrays of particles. The pathological features of NMO include perivascular deposition of immunoglobulin and activated complement, loss of astrocytic AQP4, inflammatory infiltration with granulocyte and macrophage accumulation, and demyelination with axon loss. Current evidence supports a causative role of AQP4-IgG in NMO, in which binding of AQP4-IgG to AQP4 orthogonal arrays on astrocytes initiates complement-dependent and antibody-dependent cell-mediated cytotoxicity and inflammation. Immunosuppression and plasma exchange are the mainstays of therapy for NMO optic neuritis. Novel therapeutics targeting specific steps in NMO pathogenesis are entering the development pipeline, including blockers of AQP4-IgG binding to AQP4 and inhibitors of granulocyte function. However, much work remains in understanding the unique susceptibility of the optic nerves in NMO, in developing animal models of NMO optic neuritis, and in improving therapies to preserve vision. PMID:23545439

  11. Aquaporin-4 expression contributes to decreases in brain water content during mouse postnatal development.

    PubMed

    Li, Xiumiao; Gao, Junying; Ding, Jiong; Hu, Gang; Xiao, Ming

    2013-05-01

    The water channel protein aquaporin-4 (AQP4) is implicated to facilitate water efflux from the brain parenchyma into the blood and CSF, playing a critical role in maintaining brain water homeostasis. Nevertheless, its contribution to decreases in brain water content during postnatal development remains unknown. A quantitative Western blot analysis was performed to investigate developmental expression of AQP4 in the whole mouse brain and showed that AQP4 expression level in 1 week-old brain was only 21.3% of that in the adult brain, but significantly increased to 67.4% of the adult level by 2 weeks after birth. Statistical analysis demonstrated that increased AQP4 expression partially relates to decreased brain water content in postnatal mice (r(2)=0.92 and P=0.002). Moreover, AQP4 null mice had greater brain water content than littermate controls from 2 weeks up to adult age. Consistently, mature pattern of AQP4 localization at the brain-blood and brain-CSF interfaces were completed at approximately at 2 weeks after birth. In addition, AQP4 expression in the brain stem and hypothalamus was earlier than that in the cerebral cortex and cerebellum, suggesting a brain regional variation in developmental expression of AQP4. These results characterize the developmental feature of AQP4 expression in the postnatal brain and provide direct evidence for a role of AQP4 in postnatal brain water uptake.

  12. Distribution of aquaporin 4 on sarcolemma of fast-twitch skeletal myofibres.

    PubMed

    Kaakinen, Mika; Salmela, Paula; Zelenin, Sergey; Metsikkö, Kalervo

    2007-09-01

    The aquaporin 4 (AQP4) water channel is present on the sarcolemma of fast-twitch-type skeletal myofibres. We have examined the distribution of AQP4 in relation to sarcolemmal domain structure and found that AQP4 protein is not evenly distributed on the sarcolemma. Immunofluorescence staining of isolated single myofibres indicated a punctate staining pattern overlapping with the dystrophin glycoprotein complex, but with the transverse tubule openings being left clear. Myotendinous and neuromuscular junctions also lacked AQP4, despite their high content of the dystrophin glycoprotein complex. The destruction of caveoli with methyl-beta-cyclodextrin did not change the distribution of AQP4 at the sarcolemma. Moreover, AQP4 did not float with the caveolar marker caveolin-3 in sucrose gradients after Triton X-100 extraction at 4 degrees C. These data indicated that AQP4 was not associated with caveoli. Surprisingly, m. flexor digitorum brevis fibres, although of the fast-twitch type, often lacked AQP4. Furthermore, those fibres harbouring AQP4 at the sarcolemma showed a regionalized distribution, suggesting that large areas were devoid of the protein. Blockage of the synthesized proteins in the endoplasmic reticulum with brefeldin A showed that, in spite of its regionalized sarcolemmal distribution, AQP4 was synthesized along the entire length of the fibres. These results suggest functional differences in the water permeability of the sarcolemma not only between the fast-twitch muscles, but also within single muscle fibres.

  13. Verification and spatial localization of aquaporin-5 in the ocular lens.

    PubMed

    Grey, Angus C; Walker, Kerry L; Petrova, Rosica S; Han, Jun; Wilmarth, Phillip A; David, Larry L; Donaldson, Paul J; Schey, Kevin L

    2013-03-01

    Until recently, the lens was thought to express only two aquaporin (AQP) water channels, AQP1 and AQP0. In this study we confirm lenticular AQP5 protein expression by Western blotting and mass spectrometry in lenses from a variety of species. In addition, confocal microscopy was used to map cellular distributions of AQP5 in mouse, rat and human lenses. Tandem mass spectrometry of a human lens membrane preparation revealed extensive sequence coverage (56.2%) of AQP5. Western blotting performed on total fiber cell membranes from mouse, rat, bovine and human lenses confirmed AQP5 protein expression is conserved amongst species. Western blotting of dissected lens fractions suggests that AQP5 is processed in the lens core by C-terminal truncation. Immunohistochemistry showed that AQP5 signal was most abundant in the lens outer cortex and decreased in intensity in the lens core. Furthermore, AQP5 undergoes differentiation-dependent changes in subcellular location from an intracellular localization in differentiating fiber cells to the plasma membrane of mature fiber cells upon the loss of fiber cell nuclei. Our results show that AQP5 is a significant component of lens fiber cell membranes, representing the second most abundant water channel in these cells. Together, the changes to AQP5 distribution and structure are likely to modulate the functional role of AQP5 in different regions of the lens.

  14. Verification and Spatial Localization of Aquaporin-5 in the Ocular Lens

    PubMed Central

    Grey, Angus C.; Walker, Kerry L.; Petrova, Rosica S.; Han, Jun; Wilmarth, Phillip A.; David, Larry L.; Donaldson, Paul J.; Schey, Kevin L.

    2013-01-01

    Until recently, the lens was thought to express only two Aquaporin (AQP) water channels, AQP1 and AQP0. In this study we confirm lenticular AQP5 protein expression by Western blotting and mass spectrometry in lenses from a variety of species. In addition, confocal microscopy was used to map cellular distributions of AQP5 in mouse, rat and human lenses. Tandem mass spectrometry of a human lens membrane preparation revealed extensive sequence coverage (56.2%) of AQP5. Western blotting performed on total fiber cell membranes from mouse, rat, bovine and human lenses confirmed AQP5 protein expression is conserved amongst species. Western blotting of dissected lens fractions suggests that AQP5 is processed in the lens core by C-terminal truncation. Immunohistochemistry showed that AQP5 signal was most abundant in the lens outer cortex and decreased in intensity in the lens core. Furthermore, AQP5 undergoes differentiation-dependent changes in subcellular location from an intracellular localization in differentiating fiber cells to the plasma membrane of mature fiber cells upon the loss of fiber cell nuclei. Our results show that AQP5 is a significant component of lens fiber cell membranes, representing the second most abundant water channel in these cells. Together, the changes to AQP5 distribution and structure are likely to modulate the functional role of AQP5 in different regions of the lens. PMID:23313152

  15. Rat Aquaporin-5 Is pH-Gated Induced by Phosphorylation and Is Implicated in Oxidative Stress

    PubMed Central

    Rodrigues, Claudia; Mósca, Andreia Filipa; Martins, Ana Paula; Nobre, Tatiana; Prista, Catarina; Antunes, Fernando; Cipak Gasparovic, Ana; Soveral, Graça

    2016-01-01

    Aquaporin-5 (AQP5) is a membrane water channel widely distributed in human tissues that was found up-regulated in different tumors and considered implicated in carcinogenesis in different organs and systems. Despite its wide distribution pattern and physiological importance, AQP5 short-term regulation was not reported and mechanisms underlying its involvement in cancer are not well defined. In this work, we expressed rat AQP5 in yeast and investigated mechanisms of gating, as well as AQP5’s ability to facilitate H2O2 plasma membrane diffusion. We found that AQP5 can be gated by extracellular pH in a phosphorylation-dependent manner, with higher activity at physiological pH 7.4. Moreover, similar to other mammalian AQPs, AQP5 is able to increase extracellular H2O2 influx and to affect oxidative cell response with dual effects: whereas in acute oxidative stress conditions AQP5 induces an initial higher sensitivity, in chronic stress AQP5 expressing cells show improved cell survival and resistance. Our findings support the involvement of AQP5 in oxidative stress and suggest AQP5 modulation by phosphorylation as a novel tool for therapeutics. PMID:27983600

  16. Aquaporin-4 in brain and spinal cord oedema.

    PubMed

    Saadoun, S; Papadopoulos, M C

    2010-07-28

    Brain oedema is a major clinical problem produced by CNS diseases (e.g. stroke, brain tumour, brain abscess) and systemic diseases that secondarily affect the CNS (e.g. hyponatraemia, liver failure). The swollen brain is compressed against the surrounding dura and skull, which causes the intracranial pressure to rise, leading to brain ischaemia, herniation, and ultimately death. A water channel protein, aquaporin-4 (AQP4), is found in astrocyte foot processes (blood-brain border), the glia limitans (subarachnoid cerebrospinal fluid-brain border) and ependyma (ventricular cerebrospinal fluid-brain border). Experiments using mice lacking AQP4 or alpha syntrophin (which secondarily downregulate AQP4) showed that AQP4 facilitates oedema formation in diseases causing cytotoxic (cell swelling) oedema such as cerebral ischaemia, hyponatraemia and meningitis. In contrast, AQP4 facilitates oedema elimination in diseases causing vasogenic (vessel leak) oedema and therefore AQP4 deletion aggravates brain oedema produced by brain tumour and brain abscess. AQP4 is also important in spinal cord oedema. AQP4 deletion was associated with less cord oedema and improved outcome after compression spinal cord injury in mice. Here we consider the possible routes of oedema formation and elimination in the injured cord and speculate about the role of AQP4. Finally we discuss the role of AQP4 in neuromyelitis optica (NMO), an inflammatory demyelinating disease that produces oedema in the spinal cord and optic nerves. NMO patients have circulating AQP4 IgG autoantibody, which is now used for diagnosing NMO. We speculate how NMO-IgG might produce CNS inflammation, demyelination and oedema. Since AQP4 plays a key role in the pathogenesis of CNS oedema, we conclude that AQP4 inhibitors and activators may reduce CNS oedema in many diseases.

  17. Isolated new onset 'atypical' optic neuritis in the NMO clinic: serum antibodies, prognoses and diagnoses at follow-up.

    PubMed

    Piccolo, L; Woodhall, M; Tackley, G; Juryńczyk, M; Kong, Y; Domingos, J; Gore, R; Vincent, A; Waters, P; Leite, M I; Palace, J

    2016-02-01

    Severe, recurrent or bilateral optic neuritis (ON) often falls within the neuromyelitis optica spectrum disorders (NMOSD), but the diagnosis can be particularly challenging and has important treatment implications. We report the features, course and outcomes of patients presenting with atypical ON when isolated at onset. We retrospectively analyzed 69 sequential patients referred to a single UK NMO center with isolated ON at onset. Aquaporin-4 antibody (AQP4-Ab) assessment was performed in all patients and IgG1 myelin-oligodenrocyte glycoprotein (MOG-Ab) in AQP4-Ab(neg) patients. 37 AQP4-Ab positive (AQP4-Ab(pos)) and 32 AQP4-Ab negative (AQP4-Ab(neg)) patients (8 with MOG-Ab) were identified. The AQP4-Ab(neg) group included heterogeneous diagnoses: multiple sclerosis (MS), NMO, relapsing isolated ON (RION), monophasic isolated ON and relapsing acute disseminated encephalomyelitis (ADEM)-like syndromes. Compared to AQP4-Ab(neg) patients, AQP4-Ab(pos) patients had a worse residual visual outcome from first attack (median VFSS 4 vs. 0, p = 0.010) and at last assessment (median VFSS 5 versus 2, p = 0.005). However, AQP4-Ab(neg) patients with RION also had poor visual outcome. Up to 35% of AQP4-Ab(neg) patients developed a LETM and two developed low positivity for AQP4-Ab over time. Eight AQP4-Ab(neg) patients (25%) were MOG-Ab positive, covering a range of phenotypes excluding MS; the first ON attack was often bilateral and most had relapsing disease with a poor final visual outcome [VFSS 4, range (0-6)]. In conlcusion, AQP4-Ab positivity is confirmed as a predictor of poor visual outcome but AQP4-Ab(neg) RION also had a poor visual outcome. Of those without AQP4-Ab, 25% had MOG-Ab and another 25% developed MS; thus, MOG-Ab is associated with AQP4-Ab(neg) non-MS ON.

  18. Normal immunostaining pattern for aquaporin-5 in the lesions of palmoplantar hyperhidrosis.

    PubMed

    Nakahigashi, Kyoko; Nomura, Takashi; Miyachi, Yoshiki; Kabashima, Kenji

    2013-01-01

    Aquaporin-5 (AQP-5) is a water-transporting protein expressed in mammal sweat glands. It has been reported that the expression of AQP-5 is involved in sweating of mice, rats, and horses. However, the physiological function of human AQP-5 is still uncertain. In this report, we examined the expression pattern of AQP-5 in the skin lesions of palmoplantar hyperhidrosis in patients with Nagashima-type palmoplantar hyperkeratosis (PPK). We found that there was no significant difference in AQP-5 expression in the palmoplantar skin of healthy subjects and patients with palmoplantar hyperhidrosis. Our findings suggest that a mechanism other than AQP-5 may be involved in the pathogenesis of hyperhidrosis in PPK.

  19. The effect of aquaporin 5 overexpression on the Ras signaling pathway

    SciTech Connect

    Woo, Janghee; Lee, Juna; Kim, Myoung Sook; Jang, Se Jin; Sidransky, David; Moon, Chulso

    2008-03-07

    Human aquaporin 5 (AQP5) has been shown to be overexpressed in multiple cancers, such as pancreatic cancer and colon cancer. Furthermore, it has been reported that ectopic expression of AQP5 leads to many phenotypic changes characteristic of transformation. However, the biochemical mechanism leading to transformation in AQP5-overexpressing cells has not been clearly elucidated. In this report, the overexpression of AQP5 in NIH3T3 cells demonstrated a significant effect on Ras activity and, thus, cell proliferation. Furthermore, this influence was shown to be mediated by phosphorylation of the PKA consensus site of AQP5. This is the first evidence demonstrating an association between AQP5 and a signaling pathway, namely the Ras signal transduction pathway, which may be the basis of the oncogenic properties seen in AQP-overexpressing cells.

  20. Aquaporin 4 is a Ubiquitously Expressed Isoform in the Dogfish (Squalus acanthias) Shark.

    PubMed

    Cutler, Christopher P; Maciver, Bryce; Cramb, Gordon; Zeidel, Mark

    2011-01-01

    The dogfish ortholog of aquaporin 4 (AQP4) was amplified from cDNA using degenerate PCR followed by cloning and sequencing. The complete coding region was then obtained using 5' and 3' RACE techniques. Alignment of the sequence with AQP4 amino acid sequences from other species showed that dogfish AQP4 has high levels (up to 65.3%) of homology with higher vertebrate sequences but lower levels of homology to Agnathan (38.2%) or teleost (57.5%) fish sequences. Northern blotting indicated that the dogfish mRNA was approximately 3.2 kb and was highly expressed in the rectal gland (a shark fluid secretory organ). Semi-quantitative PCR further indicates that AQP4 is ubiquitous, being expressed in all tissues measured but at low levels in certain tissues, where the level in liver > gill >  intestine. Manipulation of the external environmental salinity of groups of dogfish showed that when fish were acclimated in stages to 120% seawater (SW) or 75% SW, there was no change in AQP4 mRNA expression in either rectal gland, kidney, or esophagus/cardiac stomach. Whereas quantitative PCR experiments using the RNA samples from the same experiment, showed a significant 63.1% lower abundance of gill AQP4 mRNA expression in 120% SW-acclimated dogfish. The function of dogfish AQP4 was also determined by measuring the effect of the AQP4 expression in Xenopus laevis oocytes. Dogfish AQP4 expressing-oocytes, exhibited significantly increased osmotic water permeability (P(f)) compared to controls, and this was invariant with pH. Permeability was not significantly reduced by treatment of oocytes with mercury chloride, as is also the case with AQP4 in other species. Similarly AQP4 expressing-oocytes did not exhibit enhanced urea or glycerol permeability, which is also consistent with the water-selective property of AQP4 in other species.

  1. Enlarged extracellular space of aquaporin-4-deficient mice does not enhance diffusion of Alexa Fluor 488 or dextran polymers.

    PubMed

    Xiao, F; Hrabetová, S

    2009-06-16

    Aquaporin-4 (AQP4) water channels expressed on glia have been implicated in maintaining the volume of extracellular space (ECS). A previous diffusion study employing small cation tetramethylammonium and a real-time iontophoretic (RTI) method demonstrated an increase of about 25% in the ECS volume fraction (alpha) in the neocortex of AQP4(-/-) mice compared to AQP4(+/+) mice but no change in the hindrance imposed to diffusing molecules (tortuosity lambda). In contrast, other diffusion studies employing large molecules (dextran polymers) and a fluorescence recovery after photobleaching (FRAP) method measured a decrease of about 10%-20% in lambda in the neocortex of AQP4(-/-) mice. These conflicting findings on lambda would imply that large molecules diffuse more readily in the enlarged ECS of AQP4(-/-) mice than in wild type but small molecules do not. To test this hypothesis, we used integrative optical imaging (IOI) to measure tortuosity with a small Alexa Fluor 488 (molecular weight [MW] 547, lambda(AF)) and two large dextran polymers (MW 3000, lambda(dex3) and MW 75,000, lambda(dex75)) in the in vitro neocortex of AQP4(+/+) and AQP4(-/-) mice. We found that lambda(AF)=1.59, lambda(dex3)=1.76 and lambda(dex75)=2.30 obtained in AQP4(-/-) mice were not significantly different from lambda(AF)=1.61, lambda(dex3)=1.76, and lambda(dex75)=2.33 in AQP4(+/+) mice. These IOI results demonstrate that lambda measured with small and large molecules each remain unchanged in the enlarged ECS of AQP4(-/-) mice compared to values in AQP4(+/+) mice. Further analysis suggests that the FRAP method yields diffusion parameters not directly comparable with those obtained by IOI or RTI methods. Our findings have implications for the role of glial AQP4 in maintaining the ECS structure.

  2. Aquaporin-4 antibody titration in NMO patients treated with rituximab

    PubMed Central

    Marnetto, Fabiana; Granieri, Letizia; Capobianco, Marco; Bertolotto, Antonio

    2016-01-01

    Objective: We undertook an observational retrospective study to investigate the usefulness of aquaporin-4 (AQP4) antibodies (Ab) titration in the management of patients with neuromyelitis optica (NMO) treated with rituximab (RTX) by studying (1) the correlation between AQP4-Ab titer and disease activity, (2) the influence of RTX on antibody levels, and (3) the association between AQP4-Ab levels and responsiveness to RTX. Methods: A cell-based assay was used for AQP4-Ab titration in 322 serum samples from 7 patients with NMO treated with RTX (median follow-up 65 months), according to a treatment-to-target approach. Serum samples were collected every month following standardized procedures. Results: (1) In group analysis, AQP4-Ab titers correlated with the disease activity, showing higher titers during and preceding relapses than during remission. However, in individual analysis, an increase in AQP4-Ab titers and CD19+ B cells did not always precede a relapse. (2) A reduction of AQP4-Ab titers in the short-term and long-term period was observed during RTX treatment. (3) Reduction of AQP4-Ab titers was observed in responder patients both 3 months after RTX infusion and in the long-term follow-up. In one nonresponder patient, AQP4-Ab levels never decreased during the treatment period. Conclusions: Titration of AQP4-Abs could be useful in the clinical management of patients with NMO treated with RTX: titration before each reinfusion and 3 months after each reinfusion may provide information about responsiveness to RTX. Although a relationship among AQP4-Ab levels, disease activity, and response to RTX was observed, the usefulness of AQP4-Ab titration to predict relapses is limited. PMID:28054001

  3. Aquaporin 4 is a Ubiquitously Expressed Isoform in the Dogfish (Squalus acanthias) Shark

    PubMed Central

    Cutler, Christopher P; MacIver, Bryce; Cramb, Gordon; Zeidel, Mark

    2012-01-01

    The dogfish ortholog of aquaporin 4 (AQP4) was amplified from cDNA using degenerate PCR followed by cloning and sequencing. The complete coding region was then obtained using 5′ and 3′ RACE techniques. Alignment of the sequence with AQP4 amino acid sequences from other species showed that dogfish AQP4 has high levels (up to 65.3%) of homology with higher vertebrate sequences but lower levels of homology to Agnathan (38.2%) or teleost (57.5%) fish sequences. Northern blotting indicated that the dogfish mRNA was approximately 3.2 kb and was highly expressed in the rectal gland (a shark fluid secretory organ). Semi-quantitative PCR further indicates that AQP4 is ubiquitous, being expressed in all tissues measured but at low levels in certain tissues, where the level in liver > gill >  intestine. Manipulation of the external environmental salinity of groups of dogfish showed that when fish were acclimated in stages to 120% seawater (SW) or 75% SW, there was no change in AQP4 mRNA expression in either rectal gland, kidney, or esophagus/cardiac stomach. Whereas quantitative PCR experiments using the RNA samples from the same experiment, showed a significant 63.1% lower abundance of gill AQP4 mRNA expression in 120% SW-acclimated dogfish. The function of dogfish AQP4 was also determined by measuring the effect of the AQP4 expression in Xenopus laevis oocytes. Dogfish AQP4 expressing-oocytes, exhibited significantly increased osmotic water permeability (Pf) compared to controls, and this was invariant with pH. Permeability was not significantly reduced by treatment of oocytes with mercury chloride, as is also the case with AQP4 in other species. Similarly AQP4 expressing-oocytes did not exhibit enhanced urea or glycerol permeability, which is also consistent with the water-selective property of AQP4 in other species. PMID:22291652

  4. Increased aquaporin-4 immunoreactivity in rat brain in response to systemic hyponatremia.

    PubMed

    Vajda, Z; Promeneur, D; Dóczi, T; Sulyok, E; Frøkiaer, J; Ottersen, O P; Nielsen, S

    2000-04-13

    The present study was undertaken to assess whether the protein and mRNA expression levels of the glial water channel aquaporin-4 (AQP4) undergo downregulation and whether there is a subcellular redistribution of AQP4 protein in rat brain in response to systemic hyponatremia and brain edema. Systemic hyponatremia was induced for 4 or 48 h by combined administration of hypotonic dextrose i.p. and 8-deamino-arginine vasopressin (dDAVP) s.c. Semiquantitative immunoblotting of membrane enriched fractions showed significantly increased immunoreactivity to 164 +/- 12% (n = 6) and 153 +/- 12% (n = 6) of control levels in brain after 4 or 48 h of systemic hyponatremia, respectively. Similarly, immunoblots of cerebellar samples revealed an increase in AQP4 immunoreactivity to 136 +/- 6% (n = 6) and 218 +/- 44% (n = 6) of control levels, after 4 or 48 h of hyponatremia. In contrast, AQP4 mRNA levels were unchanged after 4 h of severe hyponatremia (104 +/- 14% of control levels; n = 17), indicating that there are no changes in AQP4 expression in response to systemic hypoosmolarity. Immunocytochemistry and high-resolution immunogold electron microscopy revealed highly polarized labeling of AQP4 in astrocyte end-feet surrounding capillaries and forming the glia limitans. This pattern of labeling was not changed whereas an increased labeling intensity of AQP4 could be observed in response to hyponatremia. In conclusion, hyponatremia causes a pronounced and rapid increase in AQP4 immunoreactivity that is not accompanied by any increase in AQP4 mRNA expression. The increased AQP4 immunosignal may reflect secondary conformational modifications of AQP4 protein, leading to enhanced antibody binding. This post-translational modification of AQP4 may participate in the adaptation of cerebral tissue to systemic hyponatremia.

  5. Novel phosphorylation of aquaporin-5 at its threonine 259 through cAMP signaling in salivary gland cells.

    PubMed

    Hasegawa, Takahiro; Azlina, Ahmad; Javkhlan, Purevjav; Yao, Chenjuan; Akamatsu, Tetsuya; Hosoi, Kazuo

    2011-09-01

    Aquaporin-5 (AQP5), a water channel, plays key roles in salivary secretion. The novel phosphorylation of AQP5 was investigated by using human salivary gland (HSG) cells and mouse salivary glands. In the HSG cells stably transfected with a wild-type mouse AQP5 construct, a protein band immunoreactive with antibody against phosphorylated PKA substrate was detected in the AQP5 immunoprecipitated sample, and its intensity was enhanced by short-term treatment of the cells with 8-bromo-cAMP, forskolin, or phorbol 12-myristate 13-acetate, but not by that with A23187 calcium ionophore. Such enhancement was inhibited in the presence of H-89, a PKA inhibitor. An AQP5 mutant (AQP5-T259A) expressed by transfection of HSG cells was not recognized by anti-phosphorylated PKA substrate antibody, even when the cells were stimulated with the protein kinase activators. Immunoblotting and immunofluorescence studies using a specific antibody detecting AQP5 phosphorylated at its Thr259 demonstrated that AQP5 was rapidly and transiently phosphorylated at the apical membrane of acinar cells in the submandibular and parotid glands after administration of isoproterenol, but not pilocarpine. Furthermore, both AQP5 and AQP5-T259A were constitutively localized at the plasma membrane in HSG cells under the resting and forskolin-stimulated conditions. These results suggest that AQP5 is phosphorylated at its Thr259 by PKA through cAMP, but not Ca(2+), signaling pathways, and that this phosphorylation does not contribute to AQP5 trafficking in the salivary gland cells.

  6. Protection of Vascular Endothelial Growth Factor to Brain Edema Following Intracerebral Hemorrhage and Its Involved Mechanisms: Effect of Aquaporin-4

    PubMed Central

    Dong, Qiang

    2013-01-01

    Vascular endothelial growth factor (VEGF) has protective effects on many neurological diseases. However, whether VEGF acts on brain edema following intracerebral hemorrhage (ICH) is largely unknown. Our previous study has shown aquaporin-4 (AQP4) plays an important role in brain edema elimination following ICH. Meanwhile, there is close relationship between VEGF and AQP4. In this study, we aimed to test effects of VEGF on brain edema following ICH and examine whether they were AQP4 dependent. Recombinant human VEGF165 (rhVEGF165) was injected intracerebroventricularly 1 d after ICH induced by microinjecting autologous whole blood into striatum. We detected perihemotomal AQP4 protein expression, then examined the effects of rhVEGF165 on perihemotomal brain edema at 1 d, 3 d, and 7 d after injection in wild type (AQP4+/+) and AQP4 knock-out (AQP4−/−) mice. Furthermore, we assessed the possible signal transduction pathways activated by VEGF to regulate AQP4 expression via astrocyte cultures. We found perihemotomal AQP4 protein expression was highly increased by rhVEGF165. RhVEGF165 alleviated perihemotomal brain edema in AQP4+/+ mice at each time point, but had no effect on AQP4−/− mice. Perihemotomal EB extravasation was increased by rhVEGF165 in AQP4−/− mice, but not AQP4+/+ mice. RhVEGF165 reduced neurological deficits and increased Nissl’s staining cells surrounding hemotoma in both types of mice and these effects were related to AQP4. RhVEGF165 up-regulated phospharylation of C-Jun amino-terminal kinase (p-JNK) and extracellular signal-regulated kinase (p-ERK) and AQP4 protein in cultured astrocytes. The latter was inhibited by JNK and ERK inhibitors. In conclusion, VEGF reduces neurological deficits, brain edema, and neuronal death surrounding hemotoma but has no influence on BBB permeability. These effects are closely related to AQP4 up-regulation, possibly through activating JNK and ERK pathways. The current study may present new insights to

  7. Unaltered Glutamate Transporter-1 Protein Levels in Aquaporin-4 Knockout Mice

    PubMed Central

    Hubbard, Jacqueline A.

    2017-01-01

    Maintenance of glutamate and water homeostasis in the brain is crucial to healthy brain activity. Astrocytic glutamate transporter-1 (GLT1) and aquaporin-4 (AQP4) are the main regulators of extracellular glutamate and osmolarity, respectively. Several studies have reported colocalization of GLT1 and AQP4, but the existence of a physical interaction between the two has not been well studied. Therefore, we used coimmunoprecipitation to determine whether a strong interaction exists between these two important molecules in mice on both a CD1 and C57BL/6 background. Furthermore, we used Western blot and immunohistochemistry to examine GLT1 levels in AQP4 knockout (AQP4−/−) mice. An AQP4-GLT1 precipitate was not detected, suggesting the lack of a strong physical interaction between AQP4 and GLT1. In addition, GLT1 protein levels remained unaltered in tissue from CD1 and C57BL/6 AQP4−/− mice. Finally, immunohistochemical analysis revealed that AQP4 and GLT1 do colocalize, but only in a region-specific manner. Taken together, these findings suggest that AQP4 and GLT1 do not have a strong physical interaction between them and are, instead, differentially regulated. PMID:28078912

  8. Is Upregulation of Aquaporin 4-M1 Isoform Responsible for the Loss of Typical Orthogonal Arrays of Particles in Astrocytomas?

    PubMed Central

    Fallier-Becker, Petra; Nieser, Maike; Wenzel, Ulrike; Ritz, Rainer; Noell, Susan

    2016-01-01

    The astrocytic endfoot membranes of the healthy blood-brain barrier—contacting the capillary—are covered with a large number of the water channel aquaporin 4 (AQP4). They form orthogonal arrays of particles (OAPs), which consist of AQP4 isoform M1 and M23. Under pathologic conditions, AQP4 is distributed over the whole cell and no or only small OAPs are found. From cell culture experiments, it is known that cells transfected only with AQP4-M1 do not form OAPs or only small ones. We hypothesized that in astrocytomas the situation may be comparable to the in vitro experiments expecting an upregulation of AQP4-M1. Quantitative Real-time PCR (qRT-PCR) of different graded astrocytomas revealed an upregulation of both isoforms AQP4 M1 and M23 in all astrocytomas investigated. In freeze fracture replicas of low-grade malignancy astrocytomas, more OAPs than in high-grade malignancy astrocytomas were found. In vitro, cultured glioma cells did not express AQP4, whereas healthy astrocytes revealed a slight upregulation of both isoforms and only a few OAPs in freeze fracture analysis. Taken together, we found a correlation between the decrease of OAPs and increasing grade of malignancy of astrocytomas but this was not consistent with an upregulation of AQP4-M1 in relation to AQP4 M23. PMID:27483250

  9. Aquaporin 5 Interacts with Fluoride and Possibly Protects against Caries

    PubMed Central

    Deeley, Kathleen; Poletta, Fernardo A.; Mereb, Juan C.; Leite, Aline L.; Barreta, Priscila A. T. M.; Silva, Thelma L.; Dizak, Piper; Ruff, Timothy; Patir, Asli; Koruyucu, Mine; Abbasoğlu, Zerrin; Casado, Priscila L.; Brown, Andrew; Zaky, Samer H.; Bayram, Merve; Küchler, Erika C.; Cooper, Margaret E.; Liu, Kai; Marazita, Mary L.; Tanboğa, İlknur; Granjeiro, José M.; Seymen, Figen; Castilla, Eduardo E.; Orioli, Iêda M.; Sfeir, Charles; Owyang, Hongjiao; Buzalaf, Marília A. R.; Vieira, Alexandre R.

    2015-01-01

    Aquaporins (AQP) are water channel proteins and the genes coding for AQP2, AQP5, and AQP6 are clustered in 12q13. Since AQP5 is expressed in serous acinar cells of salivary glands, we investigated its involvement in caries. DNA samples from 1,383 individuals from six groups were studied. Genotypes of eight single nucleotide polymorphisms covering the aquaporin locus were tested for association with caries experience. Interaction with genes involved in enamel formation was tested. The association between enamel microhardness at baseline, after creation of artificial caries lesion, and after exposure to fluoride and the genetic markers in AQP5 was tested. Finally, AQP5 expression in human whole saliva, after exposure to fluoride in a mammary gland cell line, which is known to express AQP5, and in Wistar rats was also verified. Nominal associations were found between caries experience and markers in the AQP5 locus. Since these associations suggested that AQP5 may be inhibited by levels of fluoride in the drinking water that cause fluorosis, we showed that fluoride levels above optimal levels change AQP5 expression in humans, cell lines, and rats. We have shown that AQP5 is involved in the pathogenesis of caries and likely interacts with fluoride. PMID:26630491

  10. Glio-vascular modifications caused by Aquaporin-4 deletion in the mouse retina.

    PubMed

    Nicchia, Grazia Paola; Pisani, Francesco; Simone, Laura; Cibelli, Antonio; Mola, Maria Grazia; Dal Monte, Massimo; Frigeri, Antonio; Bagnoli, Paola; Svelto, Maria

    2016-05-01

    Aquaporin-4 (AQP4) is the Central Nervous System water channel highly expressed at the perivascular glial domain. In the retina, two types of AQP4 expressing glial cells take part in the blood-retinal barrier (BRB), astrocytes and Müller cells. The aim of the present study is to investigate the effect of AQP4 deletion on the retinal vasculature by looking at typical pathological hallmark such as BRB dysfunction and gliotic condition. AQP4 dependent BRB properties were evaluated by measuring the number of extravasations in WT and AQP4 KO retinas by Evans blue injection assay. AQP4 deletion did not affect the retinal vasculature, as assessed by Isolectin B4 staining, but caused BRB impairment to the deep plexus capillaries while the superficial and intermediate capillaries were not compromised. To investigate for gliotic responses caused by AQP4 deletion, Müller cells and astrocytes were analysed by immunofluorescence and western blot, using the Müller cell marker Glutamine Synthetase (GS) and the astrocyte marker GFAP. While GS expression was not altered in AQP4 KO retinas, a strong GFAP upregulation was found at the level of AQP4 KO astrocytes at the superficial plexus and not at Müller cells at the intermediate and deep plexi. These data, together with the upregulation of inflammatory markers (TNF-α, IL-6, IL-1β and ICAM-1) in AQP4 KO retinas indicated AQP4 deletion as responsible for a gliotic phenotype. Interestingly, no GFAP altered expression was found in AQP4 siRNA treated astrocyte primary cultures. All together these results indicate that AQP4 deletion is directly responsible for BRB dysfunction and gliotic condition in the mouse retina. The selective activation of glial cells at the primary plexus suggests that different regulatory elements control the reaction of astrocytes and Müller cells. Finally, GFAP upregulation is strictly linked to gliovascular crosstalk, as it is absent in astrocytes in culture. This study is useful to understand the role

  11. Evidences for a Leaky Scanning Mechanism for the Synthesis of the Shorter M23 Protein Isoform of Aquaporin-4

    PubMed Central

    Rossi, Andrea; Pisani, Francesco; Nicchia, Grazia Paola; Svelto, Maria; Frigeri, Antonio

    2010-01-01

    Aquaporin-4 (AQP4) exists as two major isoforms that differ in the length of the N terminus, the shorter AQP4-M23 and the longer AQP4-M1. Both isoforms form tetramers, which can further aggregate in the plasma membrane to form typical orthogonal arrays of particles (OAPs) whose dimension depends on the ratio of the M1 and M23. In this study, we tested the hypothesis that the M23 isoform can be produced directly by the M1 mRNA. In cells transiently transfected with AQP4-M1 coding sequence we observed besides AQP4-M1 the additional presence of the AQP4-M23 isoform associated with the formation of typical OAPs observable by two-dimensional blue native/SDS-PAGE and total internal reflection microscopy. The mutation of the second in-frame methionine M23 in AQP4-M1 (AQP4-M1M23I) prevented the expression of the M23 isoform and the formation of OAPs. We propose “leaky scanning” as a translational mechanism for the expression of AQP4-M23 protein isoform and that the formation of OAPs may occur even in the absence of AQP4-M23 mRNA. This mechanism can have important pathophysiological implications for the cell regulation of the M1/M23 ratio and thus OAP size. In this study we also provide evidence that AQP4-M1 is mobile in the plasma membrane, that it is inserted and not excluded into immobile OAPs, and that it is an important determinant of OAP structure and size. PMID:20007705

  12. Evidences for a leaky scanning mechanism for the synthesis of the shorter M23 protein isoform of aquaporin-4: implication in orthogonal array formation and neuromyelitis optica antibody interaction.

    PubMed

    Rossi, Andrea; Pisani, Francesco; Nicchia, Grazia Paola; Svelto, Maria; Frigeri, Antonio

    2010-02-12

    Aquaporin-4 (AQP4) exists as two major isoforms that differ in the length of the N terminus, the shorter AQP4-M23 and the longer AQP4-M1. Both isoforms form tetramers, which can further aggregate in the plasma membrane to form typical orthogonal arrays of particles (OAPs) whose dimension depends on the ratio of the M1 and M23. In this study, we tested the hypothesis that the M23 isoform can be produced directly by the M1 mRNA. In cells transiently transfected with AQP4-M1 coding sequence we observed besides AQP4-M1 the additional presence of the AQP4-M23 isoform associated with the formation of typical OAPs observable by two-dimensional blue native/SDS-PAGE and total internal reflection microscopy. The mutation of the second in-frame methionine M23 in AQP4-M1 (AQP4-M1(M23I)) prevented the expression of the M23 isoform and the formation of OAPs. We propose "leaky scanning" as a translational mechanism for the expression of AQP4-M23 protein isoform and that the formation of OAPs may occur even in the absence of AQP4-M23 mRNA. This mechanism can have important pathophysiological implications for the cell regulation of the M1/M23 ratio and thus OAP size. In this study we also provide evidence that AQP4-M1 is mobile in the plasma membrane, that it is inserted and not excluded into immobile OAPs, and that it is an important determinant of OAP structure and size.

  13. Laminar-specific and developmental expression of aquaporin-4 in the mouse hippocampus

    PubMed Central

    Hsu, Mike S.; Seldin, Marcus; Lee, Darrin J.; Seifert, Gerald; Steinhäuser, Christian; Binder, Devin K.

    2011-01-01

    Mice deficient in the water channel AQP4 demonstrate increased seizure duration in response to hippocampal stimulation as well as impaired extracellular K+ clearance. However, the expression of AQP4 in the hippocampus is not well described. In this study, we investigated i) the developmental, laminar and cell-type specificity of AQP4 expression in the hippocampus; ii) the effect of Kir4.1 deletion on AQP4 expression; and iii) performed Western blot and RT-PCR analyses. AQP4 immunohistochemistry on coronal sections from WT or Kir4.1-/- mice revealed a developmentally-regulated and laminar-specific pattern, with highest expression in the CA1 stratum lacunosummoleculare (SLM) and the molecular layer (ML) of the dentate gyrus (DG). AQP4 was colocalized with the glial markers GFAP and S100ß in the hippocampus, and was also ubiquitously expressed on astrocytic endfeet around blood vessels. No difference in AQP4 immunoreactivity was observed in Kir4.1-/- mice. Electrophysiological and postrecording RT-PCR analyses of individual cells revealed that AQP4 and Kir4.1 were co-expressed in nearly all CA1 astrocytes. In NG2 cells, AQP4 was also expressed at the transcript level. This study is the first to examine subregional AQP4 expression during development of the hippocampus. The strikingly high expression of AQP4 in the CA1 SLM and DG ML identifies these regions as potential sites of astrocytic K+ and H2O regulation. These results begin to delineate the functional capabilities of hippocampal subregions and cell types for K+ and H2O homeostasis, which is critical to excitability and serves as a potential target for modulation in diverse diseases. PMID:21256195

  14. Impact of the anti-aquaporin-4 autoantibody on inner retinal structure, function and structure-function associations in Japanese patients with optic neuritis

    PubMed Central

    Matsumoto, Yoshiko; Mori, Sotaro; Ueda, Kaori; Kurimoto, Takuji; Kanamori, Akiyasu; Yamada, Yuko; Nakashima, Ichiro

    2017-01-01

    Purpose An autoantibody against aquaporin-4 (AQP4 Ab) is highly specific for neuromyelitis optica spectrum disorder and plays a pathogenic role in this disease. The purpose of this study was to investigate the impact of AQP4 Ab on inner retinal structure, function, and the structure−function relationships in eyes with optic neuritis. Methods Thirty five eyes from 25 cases who had received visual function tests and RTVue optical coherence tomography (OCT) measurement at least six months after the latest episode of optic neuritis were enrolled. Patients with multiple sclerosis were excluded. AQP4 Ab was measured using a cell-based assay. Visual acuity, mean deviation (MD) of the Humphrey visual field SITA standard 30–2 tests, retinal nerve fiber layer (RNFL), ganglion cell complex (GCC) thicknesses, and other clinical variables were compared between the AQP4 Ab-positive and -negative groups. Parameters associated with visual functions were evaluated by generalized estimating equation (GEE) models. Results The AQP4 Ab-positive group (20 eyes from 12 cases) had a higher proportion of bilateral involvement and longer duration of follow-up than the AQP4 Ab-negative group (15 eyes from 13 cases). Linear mixed effect models revealed worse MD and visual acuity in AQP4 Ab-positive eyes than those in AQP4 Ab-negative eyes after adjusting for within-patient inter-eye dependence, whereas there were no differences in RNFL and GCC thickness between the two groups. In seropositive eyes, GEE regression analyses revealed that depending on age and the number of recurrences of ON episodes, OCT parameters correlated strongly with MD and more weakly with visual acuity. Conclusions Reductions in RNFL and GCC thickness were proportional to the visual field defect in eyes with AQP4 Ab but not in eyes without AQP4 Ab. The presence of AQP4 Ab probably plays a critical role in retinal ganglion cell loss in optic neuritis. PMID:28199381

  15. The Effects of Female Sexual Hormones on the Expression of Aquaporin 5 in the Late-Pregnant Rat Uterus

    PubMed Central

    Csányi, Adrienn; Bóta, Judit; Falkay, George; Gáspár, Robert; Ducza, Eszter

    2016-01-01

    Thirteen mammalian aquaporin (AQP) water channels are known, and few of them play a role in the mammalian reproductive system. In our earlier study, the predominance of AQP5 in the late-pregnant rat uterus was proven. Our current aim was to investigate the effect of estrogen- and gestagen-related compounds on the expression of the AQP5 channel in the late-pregnant rat uterus. Furthermore, we examined the effect of hormonally-induced preterm delivery on the expression of AQP5 in the uterus. We treated pregnant Sprague-Dawley rats subcutaneously with 17β-estradiol, clomiphene citrate, tamoxifen citrate, progesterone, levonorgestrel, and medroxyprogesterone acetate. Preterm delivery was induced by subcutaneous mifepristone and intravaginal prostaglandin E2. Reverse-transcriptase PCR and Western blot techniques were used for the detection of the changes in AQP5 mRNA and protein expressions. The amount of AQP5 significantly increased after progesterone and progesterone analogs treatment on 18 and 22 days of pregnancy. The 17β-estradiol and estrogen receptor agonists did not influence the AQP5 mRNA level; however, estradiol induced a significant increase in the AQP5 protein level on the investigated days of gestation. Tamoxifen increased the AQP5 protein expression on day 18, while clomiphene citrate was ineffective. The hormonally-induced preterm birth significantly decreased the AQP5 level similarly to the day of delivery. We proved that AQP5 expression is influenced by both estrogen and progesterone in the late-pregnant rat uterus. The influence of progesterone on AQP5 expression is more predominant as compared with estrogen. PMID:27556454

  16. Actin cytoskeleton remodeling governs aquaporin-4 localization in astrocytes.

    PubMed

    Nicchia, Grazia Paola; Rossi, Andrea; Mola, Maria Grazia; Procino, Giuseppe; Frigeri, Antonio; Svelto, Maria

    2008-12-01

    Aquaporin-4 (AQP4) is constitutively concentrated in the plasma membrane of the perivascular glial processes, and its expression is altered in certain pathological conditions associated with brain edema or altered glial migration. When astrocytes are grown in culture, they lose their characteristic star-like shape and AQP4 continuous plasma membrane localization observed in vivo. In this study, we differentiated primary astrocyte cultures with cAMP and lovastatin, both able to induce glial stellation through a reorganization of F-actin cytoskeleton, and obtained AQP4 selectively localized on the cell plasma membrane associated with an increase in the plasma membrane water transport level, but only cAMP induced an increase in AQP4 total protein expression. Phosphorylation experiments indicated that AQP4 in astrocytes is neither phosphorylated nor a substrate of PKA. Depolymerization of F-actin cytoskeleton performed by cytochalasin-D suggested that F-actin cytoskeleton plays a primary role for AQP4 plasma membrane localization and during cell adhesion. Finally, AQP4 knockdown does not compromise the ability of astrocytes to stellate in the presence of cAMP, indicating that astrocyte stellation is independent of AQP4.

  17. Different pattern of aquaporin-4 expression in extensor digitorum longus and soleus during early development.

    PubMed

    Nicchia, Grazia P; Mola, Maria G; Pisoni, Michela; Frigeri, Antonio; Svelto, Maria

    2007-05-01

    Aquaporin-4 (AQP4) is the neuromuscular water channel expressed at the sarcolemma of mammalian fast-twitch fibers that mediates a high water transport rate, which is important during muscle activity. Clinical interest in the neuromuscular expression of AQP4 has increased as it is associated with the protein complex formed by dystrophin, the product of the gene affected in Duchenne muscular dystrophy. The expression of AQP4 during development has not been characterized. In this study, we analyzed the expression of AQP4 in extensor digitorum longus (EDL) and soleus, a fast- and slow-twitch muscle, respectively, during the first weeks after birth. The results show that AQP4 expression in both types of skeletal muscle occurs postnatally. The time course of expression of AQP4 in the two types of muscles was also different. Whereas the expression of AQP4 protein levels in the EDL showed a progressive increase during the first month after birth, reaching levels found in adults by day 24, the levels of the protein in the soleus showed a transient peak between day 12 and day 24 and declined thereafter, an effect that may be related to the transient high number of fast motor units innervating the soleus muscle during this time. The results suggest that AQP4 expression in skeletal muscle is under neuronal influence and contribute to the understanding of the molecular events of fiber differentiation during development.

  18. Aquaporin-4 and Cerebrovascular Diseases

    PubMed Central

    Chu, Heling; Huang, Chuyi; Ding, Hongyan; Dong, Jing; Gao, Zidan; Yang, Xiaobo; Tang, Yuping; Dong, Qiang

    2016-01-01

    Cerebrovascular diseases are conditions caused by problems with brain vasculature, which have a high morbidity and mortality. Aquaporin-4 (AQP4) is the most abundant water channel in the brain and crucial for the formation and resolution of brain edema. Considering brain edema is an important pathophysiological change after stoke, AQP4 is destined to have close relation with cerebrovascular diseases. However, this relation is not limited to brain edema due to other biological effects elicited by AQP4. Till now, multiple studies have investigated roles of AQP4 in cerebrovascular diseases. This review focuses on expression of AQP4 and the effects of AQP4 on brain edema and neural cells injuries in cerebrovascular diseases including cerebral ischemia, intracerebral hemorrhage and subarachnoid hemorrhage. In the current review, we pay more attention to the studies of recent years directly from cerebrovascular diseases animal models or patients, especially those using AQP4 gene knockout mice. This review also elucidates the potential of AQP4as an excellent therapeutic target. PMID:27529222

  19. Reduced brain edema and infarct volume in aquaporin-4 deficient mice after transient focal cerebral ischemia.

    PubMed

    Yao, Xiaoming; Derugin, Nikita; Manley, Geoffrey T; Verkman, A S

    2015-01-01

    Aquaporin-4 (AQP4) is a water channel expressed in astrocyte end-feet lining the blood-brain barrier. AQP4 deletion in mice is associated with improved outcomes in global cerebral ischemia produced by transient carotid artery occlusion, and focal cerebral ischemia produced by permanent middle cerebral artery occlusion (MCAO). Here, we investigated the consequences of 1-h transient MCAO produced by intraluminal suture blockade followed by 23 h of reperfusion. In nine AQP4(+/+) and nine AQP4(-/-) mice, infarct volume was significantly reduced by an average of 39 ± 4% at 24h in AQP4(-/-) mice, cerebral hemispheric edema was reduced by 23 ± 3%, and Evans Blue extravasation was reduced by 31 ± 2% (mean ± SEM). Diffusion-weighted magnetic resonance imaging showed greatest reduction in apparent diffusion coefficient around the occlusion site after reperfusion, with remarkably lesser reduction in AQP4(-/-) mice. The reduced infarct volume in AQP4(-/-) mice following transient MCAO supports the potential utility of therapeutic AQP4 inhibition in stroke.

  20. Serum peptide reactivities may distinguish neuromyelitis optica subgroups and multiple sclerosis

    PubMed Central

    Metz, Imke; Beißbarth, Tim; Ellenberger, David; Pache, Florence; Stork, Lidia; Ringelstein, Marius; Aktas, Orhan; Jarius, Sven; Wildemann, Brigitte; Dihazi, Hassan; Friede, Tim; Ruprecht, Klemens; Paul, Friedemann

    2016-01-01

    Objective: To assess in an observational study whether serum peptide antibody reactivities may distinguish aquaporin-4 (AQP4) antibody (Ab)–positive and -negative neuromyelitis optica spectrum disorders (NMOSD) and relapsing-remitting multiple sclerosis (RRMS). Methods: We screened 8,700 peptides that included human and viral antigens of potential relevance for inflammatory demyelinating diseases and random peptides with pooled sera from different patient groups and healthy controls to set up a customized microarray with 700 peptides. With this microarray, we tested sera from 66 patients with AQP4-Ab-positive (n = 16) and AQP4-Ab-negative (n = 19) NMOSD, RRMS (n = 11), and healthy controls (n = 20). Results: Differential peptide reactivities distinguished NMOSD subgroups from RRMS in 80% of patients. However, the 2 NMOSD subgroups were not well-discriminated, although those patients are clearly separated by their antibody reactivities against AQP4 in cell-based assays. Elevated reactivities to myelin and Epstein-Barr virus peptides were present in RRMS and to AQP4 and AQP1 peptides in AQP4-Ab-positive NMOSD. Conclusions: While AQP4-Ab-positive and -negative NMOSD subgroups are not well-discriminated by peptide antibody reactivities, our findings suggest that peptide antibody reactivities may have the potential to distinguish between both NMOSD subgroups and MS. Future studies should thus concentrate on evaluating peptide antibody reactivities for the differentiation of AQP4-Ab-negative NMOSD and MS. PMID:26894206

  1. Differential diagnosis between freshwater drowning and saltwater drowning based on intrapulmonary aquaporin-5 expression.

    PubMed

    Hayashi, Takahito; Ishida, Yuko; Mizunuma, Shinya; Kimura, Akihiko; Kondo, Toshikazu

    2009-01-01

    The intrapulmonary expression of aquaporin-5 (AQP5) was examined in an experimental drowning model and forensic autopsy cases to discuss the possibility for differentiation between freshwater drowning (FWD) and saltwater drowning (SWD). In animal experiments, mice were classified into four groups: (group I: FWD; group II: SWD; group III: postmortem immersion (PI); and group IV: cervical dislocation as controls. In group I, intrapulmonary AQP5 expression was significantly suppressed at both gene and protein levels, compared with the other three groups, and there was no significant difference in AQP5 expression among groups II to IV. In the next series, we examined AQP5 gene expression in human lung samples obtained from forensic autopsies at less than 48 h postmortem (nine FWD cases, five SWD cases, and 14 other cases). Although AQP5 mRNA could be detected in all lung samples under the employed experimental conditions, the intrapulmonary gene expression of AQP5 in FWD was significantly attenuated compared with the other groups. These observations imply that AQP5 expression in type I alveolar epithelial cells was suppressed by hypotonic water to prevent hemodilution from the physiological aspect. Moreover, the analysis of intrapulmonary AQP5 expression would be forensically useful for differentiation between FWD and SWD, or between FWD and PI.

  2. Immunodetection of aquaporin 5 in sheep salivary glands related to pasture vegetative cycle.

    PubMed

    Scocco, Paola; Aralla, Marina; Catorci, Andrea; Belardinelli, Carlo; Arrighi, Silvana

    2011-01-01

    Mammalian aquaporins (AQPs) are a family of at least 13 integral membrane proteins expressed in various epithelia, where they function as channels to permeate water and small solutes. AQP5 is widely expressed in the exocrine gland where it is likely involved in providing an appropriate amount of fluid to be secreted with granular contents. As regards AQP5 expression in the salivary glands, literature is lacking concerning domestic animal species. This study was chiefly aimed at immunohistochemically investigating the presence and localization of AQP5 in sheep mandibular and parotid glands. In addition, AQP5 immunoreactivity was comparatively evaluated in animals fed with forage containing different amounts of water related to the pasture vegetative cycle, in order to shed light on the possible response of the gland to environmental modifications. Moderate AQP5-immunoreactivity was shown at the level of the lateral surface of mandibular serous demilune cells, not affected by the pasture vegetative cycle or water content. On the contrary, the parotid gland arcinar cells showed AQP5-immunoreactivity at the level of apical and lateral plasma membrane, which was slight to very strong, according to the pasture vegetative development and interannual climatic variations. AQP5 expression is likely due to its involvement in providing appropriate saliva fluidity. Indeed, the lowest AQP5 immunoreactivity was noticed when food water content increased.

  3. Neuromyelitis optica pathogenesis and aquaporin 4

    PubMed Central

    Graber, David J; Levy, Michael; Kerr, Douglas; Wade, William F

    2008-01-01

    Neuromyelitis optica (NMO) is a severe, debilitating human disease that predominantly features immunopathology in the optic nerves and the spinal cord. An IgG1 autoantibody (NMO-IgG) that binds aquaporin 4 (AQP4) has been identified in the sera of a significant number of NMO patients, as well as in patients with two related neurologic conditions, bilateral optic neuritis (ON), and longitudinal extensive transverse myelitis (LETM), that are generally considered to lie within the NMO spectrum of diseases. NMO-IgG is not the only autoantibody found in NMO patient sera, but the correlation of pathology in central nervous system (CNS) with tissues that normally express high levels of AQP4 suggests NMO-IgG might be pathogenic. If this is the case, it is important to identify and understand the mechanism(s) whereby an immune response is induced against AQP4. This review focuses on open questions about the "events" that need to be understood to determine if AQP4 and NMO-IgG are involved in the pathogenesis of NMO. These questions include: 1) How might AQP4-specific T and B cells be primed by either CNS AQP4 or peripheral pools of AQP4? 2) Do the different AQP4-expressing tissues and perhaps the membrane structural organization of AQP4 influence NMO-IgG binding efficacy and thus pathogenesis? 3) Does prior infection, genetic predisposition, or underlying immune dysregulation contribute to a confluence of events which lead to NMO in select individuals? A small animal model of NMO is essential to demonstrate whether AQP4 is indeed the incipient autoantigen capable of inducing NMO-IgG formation and NMO. If the NMO model is consistent with the human disease, it can be used to examine how changes in AQP4 expression and blood-brain barrier (BBB) integrity, both of which can be regulated by CNS inflammation, contribute to inductive events for anti-AQP4-specific immune response. In this review, we identify reagents and experimental questions that need to be developed and addressed

  4. Aquaporin-4 water channels and synaptic plasticity in the hippocampus.

    PubMed

    Scharfman, Helen E; Binder, Devin K

    2013-12-01

    Aquaporin-4 (AQP4) is the major water channel expressed in the central nervous system (CNS) and is primarily expressed in glial cells. Many studies have shown that AQP4 regulates the response of the CNS to insults or injury, but far less is known about the potential for AQP4 to influence synaptic plasticity or behavior. Recent studies have examined long-term potentiation (LTP), long-term depression (LTD), and behavior in AQP4 knockout (KO) and wild-type mice to gain more insight into its potential role. The results showed a selective effect of AQP4 deletion on LTP of the Schaffer collateral pathway in hippocampus using an LTP induction protocol that simulates pyramidal cell firing during theta oscillations (theta-burst stimulation; TBS). However, LTP produced by a different induction protocol was unaffected. There was also a defect in LTD after low frequency stimulation (LFS) in AQP4 KO mice. Interestingly, some slices from AQP4 KO mice exhibited LTD after TBS instead of LTP, or LTP following LFS instead of LTD. These data suggest that AQP4 and astrocytes influence the polarity of long-term synaptic plasticity (potentiation or depression). These potentially powerful roles expand the influence of AQP4 and astrocytes beyond the original suggestions related to regulation of extracellular potassium and water balance. Remarkably, AQP4 KO mice did not show deficits in basal transmission, suggesting specificity for long-term synaptic plasticity. The mechanism appears to be related to neurotrophins and specifically brain-derived neurotrophic factor (BDNF) because pharmacological blockade of neurotrophin trk receptors or scavenging ligands such as BDNF restored plasticity. The in vitro studies predicted effects in vivo of AQP4 deletion because AQP4 KO mice performed worse using a task that requires memory for the location of objects (object placement). However, performance on other hippocampal-dependent tasks was spared. The results suggest an unanticipated and selective

  5. Systemic administration of lipopolysaccharide increases the expression of aquaporin-4 in the rat anterior pituitary gland.

    PubMed

    Kuwahara-Otani, Sachi; Maeda, Seishi; Tanaka, Koichi; Hayakawa, Tetsu; Seki, Makoto

    2013-01-01

    We investigated the effects of lipopolysaccharide (LPS)-induced endotoxemia on the expression of aquaporin-4 (AQP4) in the rat anterior pituitary gland, using the real-time polymerase chain reaction and immunohistochemistry. After intraperitoneal injection of LPS, the level of AQP4 mRNA doubled at 2, 4 and 8 hr. Immunohistochemical analysis showed an increase with time in AQP4 immunostaining in folliculo-stellate cells following LPS injection; the intensity of immunoreactivity peaked at 8 hr. At the same time, some cyst-like structures, formed by AQP4-positive cells, were observed. These findings indicate that LPS induces the expression of AQP4 in the anterior pituitary gland. The present results should provide an important key to elucidate the pathogenesis of the anterior pituitary gland during endotoxemia.

  6. Patient vs provider reports of aberrant medication-taking behavior among opioid-treated patients with chronic pain who report misusing opioid medication.

    PubMed

    Nikulina, Valentina; Guarino, Honoria; Acosta, Michelle C; Marsch, Lisa A; Syckes, Cassandra; Moore, Sarah K; Portenoy, Russell K; Cruciani, Ricardo A; Turk, Dennis C; Rosenblum, Andrew

    2016-08-01

    During long-term opioid therapy for chronic noncancer pain, monitoring medication adherence of patients with a history of aberrant opioid medication-taking behaviors (AMTB) is an essential practice. There is limited research, however, into the concordance among existing monitoring tools of self-report, physician report, and biofluid screening. This study examined associations among patient and provider assessments of AMTB and urine drug screening using data from a randomized trial of a cognitive-behavioral intervention designed to improve medication adherence and pain-related outcomes among 110 opioid-treated patients with chronic pain who screened positive for AMTB and were enrolled in a pain program. Providers completed the Aberrant Behavior Checklist (ABC) and patients completed the Current Opioid Misuse Measure (COMM) and the Chemical Coping Inventory (CCI). In multivariate analyses, ABC scores were compared with COMM and CCI scores, while controlling for demographics and established risk factors for AMTB, such as pain severity. Based on clinical cutoffs, 84% of patients reported clinically significant levels of AMTB and providers rated 36% of patients at elevated levels. Provider reports of AMTB were not correlated with COMM or CCI scores. However, the ABC ratings of experienced providers (nurse practitioners/attending physicians) were higher than those of less experienced providers (fellows) and were correlated with CCI scores and risk factors for AMTB. Associations between patient- and provider-reported AMTB and urine drug screening results were low and largely nonsignificant. In conclusion, concordance between patient and provider reports of AMTB among patients with chronic pain prescribed opioid medication varied by provider level of training.

  7. Altered aquaporin-4 expression in human muscular dystrophies: a common feature?

    PubMed

    Frigeri, Antonio; Nicchia, Grazia Paola; Repetto, Silvia; Bado, Massimo; Minetti, Carlo; Svelto, Maria

    2002-07-01

    Duchenne Muscular Dystrophy (DMD) is a progressive lethal muscle disease that affects young boys. Dystrophin, absent in DMD and reduced in the milder form Becker Muscular Dystrophy (BMD), binds to several membrane-associated proteins known as dystrophin-associated proteins (DAPs). Once this critical structural link is disrupted, muscle fibers become more vulnerable to mechanical and osmotic stress. Recently, we have reported that the expression of aquaporin-4 (AQP4), a water-selective channel expressed in the sarcolemma of fast-twitch fibers and astrocyte end-feet, is drastically reduced in the muscle and brain of the mdx mouse, the animal model of DMD. In the present study, we analyzed the expression of AQP4 in several DMD/BMD patients of different ages with different mutations in the dystrophin gene. Immunofluorescence results indicate that, compared with healthy control children, AQP4 is reduced severely in all the DMD muscular biopsies analyzed and in 50% of the analyzed BMD. Western blot analysis revealed that the deficiency in sarcolemma AQP4 staining is due to a reduction in total AQP4 muscle protein content rather than to changes in immunoreactivity. Double-immunostaining experiments indicate that AQP4 reduction is independent of changes in the fiber myosin heavy chain composition. AQP4 and a-syntrophin analysis of BMD muscular biopsies revealed that the expression and stability of AQP4 in the sarcolemma does not always decrease when a-syntrophin is strongly reduced. Finally, limb-girdle muscular dystrophy biopsies and facioscapulohumeral muscular dystrophy revealed that AQP4 expression was not altered in these forms of muscular dystrophy. These experiments provide the first evidence of AQP4 reduction in a human pathology and show that this deficiency is an important feature of DMD/BMD.

  8. Aquaporins in skeletal muscle: reassessment of the functional role of aquaporin-4.

    PubMed

    Frigeri, Antonio; Nicchia, Grazia Paola; Balena, Rosalba; Nico, Beatrice; Svelto, Maria

    2004-05-01

    Aquaporin-4 (AQP4) is the major water channel of the neuromuscular system, but its physiological function in both perivascular astrocytes and skeletal muscle sarcolemma is unclear. The purpose of this study was to assess the following in skeletal muscle: a) the expression of all cloned water cannels; b) the functional role of AQP4 using sarcolemma vesicles purified by means of several fractionation methods, and c) the functional effect of AQP4 reduction in mdx mice, the animal model of Duchenne muscular dystrophy (DMD). Immunofluorescence and immunoblot experiments performed with affinity purified antibodies revealed that only AQP1 and AQP4 are expressed in mouse skeletal muscle: AQP1 in endothelial cells of continuous capillaries and AQP4 on the plasma membrane of muscle fiber. Plasma membrane vesicle purification was performed with a procedure extensively used to purify and characterize dystrophin-associated proteins (DAPs) from rabbit skeletal muscle. Western blot analysis showed strong co-enrichment of the analyzed DAPs and AQP4, indicating that the membrane vesicle preparation was highly enriched in sarcolemma. Stopped-flow light-scattering measurements showed high osmotic water permeability of sarcolemma vesicles (approximately 150 microm/s) compatible with the AQP-mediated pathway for water movement. Sarcolemma vesicles prepared from mdx mice revealed, in parallel with AQP4 disappearance from the plasma membrane, a strong reduction in water permeability compared with wild-type mice. Altogether, these results demonstrate high AQP4-mediated water permeability of the skeletal muscle sarcolemma. Expression of sarcolemmal AQP4 together with that of vascular AQP1 may be responsible for the fast water transfer from the blood into the muscle during intense activity. These data imply an important role for aquaporins in skeletal muscle physiology as well as an involvement of AQP4 in the molecular alterations that occur in the muscle of DMD patients.

  9. Aquaporin-4 Cell-Surface Expression and Turnover Are Regulated by Dystroglycan, Dynamin, and the Extracellular Matrix in Astrocytes

    PubMed Central

    Tham, Daniel Kai Long; Joshi, Bharat; Moukhles, Hakima

    2016-01-01

    The water-permeable channel aquaporin-4 (AQP4) is highly expressed in perivascular astrocytes of the mammalian brain and represents the major conduit for water across the blood-brain barrier. Within these cells, AQP4 is found in great quantities at perivascular endfoot sites but is detected in lesser amounts at the membrane domains within the brain parenchyma. We had previously established that this polarization was regulated by the interaction between dystroglycan (DG), an extracellular matrix receptor that is co-expressed with AQP4, and the laminin that is contained within the perivascular basal lamina. In the present study, we have attempted to describe the mechanisms that underlie this regulation, using primary astrocyte cultures. Via biotinylation, we found that the cell-surface expression of AQP4 is DG-dependent and is potentiated by laminin. We also determined that this laminin-dependent increase occurs not through an upregulation of total AQP4 levels, but rather from a redirection of AQP4 from an intracellular, EEA-1-associated pool to the cell surface. We then demonstrated an association between DG and dynamin and showed that dynamin functioned in conjunction with clathrin to regulate surface AQP4 amounts. Furthermore, we observed that DG preferentially binds to the inactive forms of dynamin, suggesting that this interaction was inhibitory for AQP4 endocytosis. Finally, we showed that laminin selectively upregulates the cell-surface expression of the M23 isoform of AQP4. Our data therefore indicate that the dual interation of DG with laminin and dynamin is involved in the regulation of AQP4 internalization, leading to its asymmetric enrichment at perivascular astrocyte endfeet. PMID:27788222

  10. Aquaporin-4 expression in the cerebrospinal fluid in congenital human hydrocephalus

    PubMed Central

    2013-01-01

    Background Aquaporin-4 (AQP4) is a water channel mainly located in the ventricular ependymal cells (brain-CSF barrier), the sub-ependymal glia, glia limitans and in end-feet of astrocytes in at the blood–brain barrier (BBB). Methods In the present work, the expression of AQP4 in the cerebrospinal fluid (CSF) in control and congenital human hydrocephalus infants (obstructive and communicating), was analysed by Western-blot and enzyme immunoassay (ELISA). Results AQP4 was found to be high compared to the control in the CSF in congenital hydrocephalus patients. Western-blot showed higher values for AQP4 than controls in communicating hydrocephalus (communicating: 38.3%, control: 6.9% p < 0.05) although the increase was not significant in obstructive hydrocephalus (obstructive: 14.7%). The AQP4 quantification by ELISA also showed that, the mean concentration of AQP4 in CSF was significantly higher in communicating hydrocephalus (communicating: 11.32 ± 0.69 ng/ml, control: 8.61 ± 0.31 ng/ml; p < 0.05). However, there was no increase over control in obstructive hydrocephalus (obstructive: 8.65 ± 0.80 ng/ml). Conclusions AQP4 has a modulatory effect on ependyma stability and acts in CSF production and reabsorption. Therefore, the increase of AQP4 in the CSF in congenital hydrocephalus could be due to the fact that AQP4 passes from the parenchyma to the CSF and this AQP4 movement may be a consequence of ependyma denudation. PMID:23659378

  11. Autoantibodies against muscarinic type 3 receptor in Sjögren's syndrome inhibit aquaporin 5 trafficking.

    PubMed

    Lee, Byung Ha; Gauna, Adrienne E; Perez, Geidys; Park, Yun-jong; Pauley, Kaleb M; Kawai, Toshihisa; Cha, Seunghee

    2013-01-01

    Sjögren's syndrome (SjS) is a chronic autoimmune disease that mainly targets the salivary and lacrimal glands. It has been controversial whether anti-muscarinic type 3 receptor (α-M3R) autoantibodies in patients with SjS inhibit intracellular trafficking of aquaporin-5 (AQP5), water transport protein, leading to secretory dysfunction. To address this issue, GFP-tagged human AQP5 was overexpressed in human salivary gland cells (HSG-hAQP5) and monitored AQP5 trafficking to the plasma membrane following carbachol (CCh, M3R agonist) stimulation. AQP5 trafficking was indeed mediated by M3R stimulation, shown in partial blockage of trafficking by M3R-antagonist 4-DAMP. HSG-hAQP5 pre-incubated with SjS plasma for 24 hours significantly reduced AQP5 trafficking with CCh, compared with HSG-hAQP5 pre-incubated with healthy control (HC) plasma. This inhibition was confirmed by monoclonal α-M3R antibody and pre-absorbed plasma. Interestingly, HSG-hAQP5 pre-incubated with SjS plasma showed no change in cell volume, compared to the cells incubated with HC plasma showing shrinkage by twenty percent after CCh-stimulation. Our findings clearly indicate that binding of anti-M3R autoantibodies to the receptor, which was verified by immunoprecipitation, suppresses AQP5 trafficking to the membrane and contribute to impaired fluid secretion in SjS. Our current study urges further investigations of clinical associations between SjS symptoms, such as degree of secretory dysfunction, cognitive impairment, and/or bladder irritation, and different profiles (titers, isotypes, and/or specificity) of anti-M3R autoantibodies in individuals with SjS.

  12. Lack of sex-linked differences in cerebral edema and aquaporin-4 expression after experimental stroke

    PubMed Central

    Liu, Xiaoqin; Zhang, Wenri; Alkayed, Nabil J; Froehner, Stanley C; Adams, Marvin E; Amiry-Moghaddam, Mahmood; Ottersen, Ole Petter; Hurn, Patricia D; Bhardwaj, Anish

    2009-01-01

    Aquaporin-4 (AQP4) has been shown to be important in the evolution of stroke-associated cerebral edema. However, the role of AQP4 in stroke-associated cerebral edema as it pertains to sex has not been previously studied. The perivascular pool of AQP4 is important in the influx and efflux of water during focal cerebral ischemia. We used mice with targeted disruption of the gene encoding α-syntrophin (α-Syn−/−) that lack the perivascular AQP4 pool but retain the endothelial pool of this protein. Infarct volume at 72h after transient focal ischemia (90 mins) in isoflurane-anesthetized mice was attenuated in both sexes with α-Syn deletion as compared with their wild-type (WT) counterparts. There were no sex differences in hemispheric water content in WT and α-Syn−/− mice or regional AQP4 expression in WT mice. In neither sex did α-Syn deletion lead to alterations in end-ischemic regional cerebral blood flow (rCBF). These data suggest that after experimental stroke: (1) there is no difference in stroke-associated cerebral edema based on sex, (2) AQP4 does not involve in sex-based differences in stroke volume, and (3) perivascular pool of AQP4 has no significant role in end-ischemic rCBF. PMID:18648381

  13. Serological markers associated with neuromyelitis optica spectrum disorders in South India

    PubMed Central

    Pandit, Lekha; Sato, Douglas Kazutoshi; Mustafa, Sharik; Takahashi, Toshiyuki; D’Cunha, Anitha; Malli, Chaithra; Sudhir, Akshatha; Fujihara, Kazuo

    2016-01-01

    Background: Neuromyelitis optica spectrum disorders (NMOSDs) represent 20% of all demyelinating disorders in South India. No studies have determined the seroprevalence to both antibodies against aquaporin-4* and antimyelin oligodendrocyte glycoprotein antibody (anti-MOG+) in this population. Objective: To identify and characterize seropositive patients for anti-aquaporin-4 antibody (anti-AQP4+) and anti-MOG+ in South India. Materials and Methods: We included 125 consecutive patients (15 children) who were serologically characterized using live transfected cells to human M23-AQP4 or full-length MOG. Results: Among a total of 125 patients, 30.4% of patients were anti-AQP4+, 20% were anti-MOG+, and 49.6% were seronegative. No patient was positive for both. Anti-MOG+ patients represented 28.7% (25/87) of seronegative NMOSD. In comparison to anti-AQP4+ patients, anti-MOG+ patients were commonly male, had less frequent attacks and milder disability on expanded disability status score scale. Seronegative patients were also predominantly male, 36% (9/25) had monophasic longitudinally extensive transverse myelitis and disability was comparable with anti-AQP4+ patients. Lumbar cord involvement was common in anti-MOG+ and seronegatives, whereas anti-AQP4+ patients had more cervical lesions. Conclusion: Anti-AQP4+/anti-MOG + patients accounted for nearly half of the patients suspected of having NMOSD in South India, indicating that antibody testing may be useful on the management of subgroups with different prognosis. PMID:27994362

  14. Effects of Different Doses of Levetiracetam on Aquaporin 4 Expression in Rats with Brain Edema Following Fluid Percussion Injury

    PubMed Central

    Jin, Hongbo; Li, Wenling; Dong, Changzheng; Ma, Li; Wu, Jiang; Zhao, Wenqing

    2016-01-01

    Background This study was designed to investigate the effects of different doses of levetiracetam on aquaporin 4 (AQP4) expression in rats after fluid percussion injury. Material/Methods Sprague-Dawley rats were randomly divided into 4 groups: sham operation group, traumatic brain injury group, low-dose levetiracetam group, and high-dose levetiracetam group. Brain edema models were established by fluid percussion injury, and intervened by the administration of levetiracetam. Samples from the 4 groups were collected at 2, 6, 12, and 24 h, and at 3 and 7 days after injury. Histological observation was performed using hematoxylin-eosin staining and immunohistochemical staining. AQP4 and AQP4 mRNA expression was detected using Western blot assay and RT-PCR. Brain water content was measured by the dry-wet method. Results Compared with the traumatic brain injury group, brain water content, AQP4 expression, and AQP4 mRNA expression were lower in the levetiracetam groups at each time point and the differences were statistically significant (P<0.05). The intervention effects of high-dose levetiracetam were more apparent. Conclusions Levetiracetam can lessen brain edema from fluid percussion injury by down-regulating AQP4 and AQP4 mRNA expression. There is a dose-effect relationship in the preventive effect of levetiracetam within a certain extent. PMID:26927633

  15. Effects of Different Doses of Levetiracetam on Aquaporin 4 Expression in Rats with Brain Edema Following Fluid Percussion Injury.

    PubMed

    Jin, Hongbo; Li, Wenling; Dong, Changzheng; Ma, Li; Wu, Jiang; Zhao, Wenqing

    2016-02-29

    BACKGROUND This study was designed to investigate the effects of different doses of levetiracetam on aquaporin 4 (AQP4) expression in rats after fluid percussion injury. MATERIAL AND METHODS Sprague-Dawley rats were randomly divided into 4 groups: sham operation group, traumatic brain injury group, low-dose levetiracetam group, and high-dose levetiracetam group. Brain edema models were established by fluid percussion injury, and intervened by the administration of levetiracetam. Samples from the 4 groups were collected at 2, 6, 12, and 24 h, and at 3 and 7 days after injury. Histological observation was performed using hematoxylin-eosin staining and immunohistochemical staining. AQP4 and AQP4 mRNA expression was detected using Western blot assay and RT-PCR. Brain water content was measured by the dry-wet method. RESULTS Compared with the traumatic brain injury group, brain water content, AQP4 expression, and AQP4 mRNA expression were lower in the levetiracetam groups at each time point and the differences were statistically significant (P<0.05). The intervention effects of high-dose levetiracetam were more apparent. CONCLUSIONS Levetiracetam can lessen brain edema from fluid percussion injury by down-regulating AQP4 and AQP4 mRNA expression. There is a dose-effect relationship in the preventive effect of levetiracetam within a certain extent.

  16. Expression of aquaporin-4 and pathological characteristics of brain injury in a rat model of traumatic brain injury

    PubMed Central

    ZHANG, CHENGCHENG; CHEN, JIANQIANG; LU, HONG

    2015-01-01

    Aquaporin 4 (AQP4) is a widely distributed membrane protein, which is found in glial cells, ependymocytes and capillary endothelial cells in the brain, and particularly in the choroid plexus. AQP4 is a key regulator of water metabolism, and changes in its expression following brain injury are associated with pathological changes in the damaged side of the brain; however, the effects of brain injury on AQP4 and injury-induced pathological changes in the contralateral non-damaged side of the brain remain to be fully elucidated. In the present study, male Sprague-Dawley rats were subjected to traumatic brain injury (TBI) and changes in brain water content, the expression of AQP4 expression and pathological characteristics in the damaged and contralateral non-damaged sides of the brain were examined. In the damaged side of the brain, vasogenic edema appeared first, followed by cellular edema. The aggravated cellular edema in the damaged side of the brain resulted in two periods of peak edema severity. Pathological changes in the contralateral non-damaged side of the brain occurred later than those in the damaged side; cellular edema appeared first, followed by vasogenic edema, which was alleviated earlier than the cellular edema. AQP4 was downregulated during vasogenic edema, and upregulated during cellular edema. Taken together, these results suggested that the downregulation of AQP4 was a result of vasogenic edema and that the upregulation of AQP4 may have induced cellular edema. PMID:26459070

  17. Identification of Two Major Conformational Aquaporin-4 Epitopes for Neuromyelitis Optica Autoantibody Binding*

    PubMed Central

    Pisani, Francesco; Mastrototaro, Mauro; Rossi, Andrea; Nicchia, Grazia Paola; Tortorella, Carla; Ruggieri, Maddalena; Trojano, Maria; Frigeri, Antonio; Svelto, Maria

    2011-01-01

    Neuromyelitis optica (NMO) is an autoimmune demyelinating disease characterized by the presence of anti-aquaporin-4 (AQP4) antibodies in the patient sera. We recently reported that these autoantibodies are able to bind AQP4 when organized in the supramolecular structure called the orthogonal array of particles (OAP). To map the antigenic determinants, we produced a series of AQP4 mutants based on multiple alignment sequence analysis between AQP4 and other OAP-forming AQPs. Mutations were introduced in the three extracellular loops (A, C, and E), and the binding capacity of NMO sera was tested on AQP4 mutants. Results indicate that one group of sera was able to recognize a limited portion of loop C containing the amino acid sequence 146GVT(T/M)V150. A second group of sera was characterized by a predominant role of loop A. Deletion of four AQP4-specific amino acids (61G(S/T)E(N/K)64) in loop A substantially affected the binding of this group of sera. However, the binding capacity was further reduced when amino acids in loop A were mutated together with those in loop E or when those in loop C were mutated in combination with loop E. Finally, a series of AQP0 mutants were produced in which the extracellular loops were progressively changed to make them identical to AQP4. Results showed that none of the mutants was able to reproduce in AQP0 the NMO-IgG epitopes, indicating that the extracellular loop sequence by itself was not sufficient to determine the rearrangement required to create the epitopes. Although our data highlight the complexity of the disease, this study identifies key immunodominant epitopes and provides direct evidence that the transition from AQP4 tetramers to AQP4-OAPs involves conformational changes of the extracellular loops. PMID:21212277

  18. The central role of aquaporins in the pathophysiology of ischemic stroke

    PubMed Central

    Vella, Jasmine; Zammit, Christian; Di Giovanni, Giuseppe; Muscat, Richard; Valentino, Mario

    2015-01-01

    Stroke is a complex and devastating neurological condition with limited treatment options. Brain edema is a serious complication of stroke. Early edema formation can significantly contribute to infarct formation and thus represents a promising target. Aquaporin (AQP) water channels contribute to water homeostasis by regulating water transport and are implicated in several disease pathways. At least 7 AQP subtypes have been identified in the rodent brain and the use of transgenic mice has greatly aided our understanding of their functions. AQP4, the most abundant channel in the brain, is up-regulated around the peri-infarct border in transient cerebral ischemia and AQP4 knockout mice demonstrate significantly reduced cerebral edema and improved neurological outcome. In models of vasogenic edema, brain swelling is more pronounced in AQP4-null mice than wild-type providing strong evidence of the dual role of AQP4 in the formation and resolution of both vasogenic and cytotoxic edema. AQP4 is co-localized with inwardly rectifying K+-channels (Kir4.1) and glial K+ uptake is attenuated in AQP4 knockout mice compared to wild-type, indicating some form of functional interaction. AQP4-null mice also exhibit a reduction in calcium signaling, suggesting that this channel may also be involved in triggering pathological downstream signaling events. Associations with the gap junction protein Cx43 possibly recapitulate its role in edema dissipation within the astroglial syncytium. Other roles ascribed to AQP4 include facilitation of astrocyte migration, glial scar formation, modulation of inflammation and signaling functions. Treatment of ischemic cerebral edema is based on the various mechanisms in which fluid content in different brain compartments can be modified. The identification of modulators and inhibitors of AQP4 offer new therapeutic avenues in the hope of reducing the extent of morbidity and mortality in stroke. PMID:25904843

  19. Identification of two major conformational aquaporin-4 epitopes for neuromyelitis optica autoantibody binding.

    PubMed

    Pisani, Francesco; Mastrototaro, Mauro; Rossi, Andrea; Nicchia, Grazia Paola; Tortorella, Carla; Ruggieri, Maddalena; Trojano, Maria; Frigeri, Antonio; Svelto, Maria

    2011-03-18

    Neuromyelitis optica (NMO) is an autoimmune demyelinating disease characterized by the presence of anti-aquaporin-4 (AQP4) antibodies in the patient sera. We recently reported that these autoantibodies are able to bind AQP4 when organized in the supramolecular structure called the orthogonal array of particles (OAP). To map the antigenic determinants, we produced a series of AQP4 mutants based on multiple alignment sequence analysis between AQP4 and other OAP-forming AQPs. Mutations were introduced in the three extracellular loops (A, C, and E), and the binding capacity of NMO sera was tested on AQP4 mutants. Results indicate that one group of sera was able to recognize a limited portion of loop C containing the amino acid sequence (146)GVT(T/M)V(150). A second group of sera was characterized by a predominant role of loop A. Deletion of four AQP4-specific amino acids ((61)G(S/T)E(N/K)(64)) in loop A substantially affected the binding of this group of sera. However, the binding capacity was further reduced when amino acids in loop A were mutated together with those in loop E or when those in loop C were mutated in combination with loop E. Finally, a series of AQP0 mutants were produced in which the extracellular loops were progressively changed to make them identical to AQP4. Results showed that none of the mutants was able to reproduce in AQP0 the NMO-IgG epitopes, indicating that the extracellular loop sequence by itself was not sufficient to determine the rearrangement required to create the epitopes. Although our data highlight the complexity of the disease, this study identifies key immunodominant epitopes and provides direct evidence that the transition from AQP4 tetramers to AQP4-OAPs involves conformational changes of the extracellular loops.

  20. Aquaporin-4 Dynamics in Orthogonal Arrays in Live Cells Visualized by Quantum Dot Single Particle Tracking

    PubMed Central

    Crane, Jonathan M.; Van Hoek, Alfred N.; Skach, William R.

    2008-01-01

    Freeze-fracture electron microscopy (FFEM) indicates that aquaporin-4 (AQP4) water channels can assemble in cell plasma membranes in orthogonal arrays of particles (OAPs). We investigated the determinants and dynamics of AQP4 assembly in OAPs by tracking single AQP4 molecules labeled with quantum dots at an engineered external epitope. In several transfected cell types, including primary astrocyte cultures, the long N-terminal “M1” form of AQP4 diffused freely, with diffusion coefficient ∼5 × 10−10 cm2/s, covering ∼5 μm in 5 min. The short N-terminal “M23” form of AQP4, which by FFEM was found to form OAPs, was relatively immobile, moving only ∼0.4 μm in 5 min. Actin modulation by latrunculin or jasplakinolide did not affect AQP4-M23 diffusion, but deletion of its C-terminal postsynaptic density 95/disc-large/zona occludens (PDZ) binding domain increased its range by approximately twofold over minutes. Biophysical analysis of short-range AQP4-M23 diffusion within OAPs indicated a spring-like potential, with a restoring force of ∼6.5 pN/μm. These and additional experiments indicated that 1) AQP4-M1 and AQP4-M23 isoforms do not coassociate in OAPs; 2) OAPs can be imaged directly by total internal reflection fluorescence microscopy; and 3) OAPs are relatively fixed, noninterconvertible assemblies that do not require cytoskeletal or PDZ-mediated interactions for formation. Our measurements are the first to visualize OAPs in live cells. PMID:18495865

  1. Aquaporin-4 in Astroglial Cells in the CNS and Supporting Cells of Sensory Organs—A Comparative Perspective

    PubMed Central

    Gleiser, Corinna; Wagner, Andreas; Fallier-Becker, Petra; Wolburg, Hartwig; Hirt, Bernhard; Mack, Andreas F.

    2016-01-01

    The main water channel of the brain, aquaporin-4 (AQP4), is one of the classical water-specific aquaporins. It is expressed in many epithelial tissues in the basolateral membrane domain. It is present in the membranes of supporting cells in most sensory organs in a specifically adapted pattern: in the supporting cells of the olfactory mucosa, AQP4 occurs along the basolateral aspects, in mammalian retinal Müller cells it is highly polarized. In the cochlear epithelium of the inner ear, it is expressed basolaterally in some cells but strictly basally in others. Within the central nervous system, aquaporin-4 (AQP4) is expressed by cells of the astroglial family, more specifically, by astrocytes and ependymal cells. In the mammalian brain, AQP4 is located in high density in the membranes of astrocytic endfeet facing the pial surface and surrounding blood vessels. At these locations, AQP4 plays a role in the maintenance of ionic homeostasis and volume regulation. This highly polarized expression has not been observed in the brain of fish where astroglial cells have long processes and occur mostly as radial glial cells. In the brain of the zebrafish, AQP4 immunoreactivity is found along the radial extent of astroglial cells. This suggests that the polarized expression of AQP4 was not present at all stages of evolution. Thus, a polarized expression of AQP4 as part of a control mechanism for a stable ionic environment and water balanced occurred at several locations in supporting and glial cells during evolution. This initially basolateral membrane localization of AQP4 is shifted to highly polarized expression in astrocytic endfeet in the mammalian brain and serves as a part of the neurovascular unit to efficiently maintain homeostasis. PMID:27571065

  2. Sera from patients with seropositive neuromyelitis optica spectral disorders caused the degeneration of rodent optic nerve.

    PubMed

    Matsumoto, Yoshiko; Kanamori, Akiyasu; Nakamura, Makoto; Takahashi, Toshiyuki; Nakashima, Ichiro; Negi, Akira

    2014-02-01

    Neuromyelitis optica (NMO) is an autoimmune inflammatory, neurodestructive disease primarily targeting the optic nerve and spinal cord. An autoantibody against water channel protein aquaporin-4 (AQP4), which is expressed at endofeet of astrocytes has been implicated in the pathogenesis of NMO. We evaluated the impact of sera of seropositive patients with NMO spectrum disorders (NMOSDs) on the rodent optic nerve and retina. Serum was obtained either from patients with seropositive NMOSD (AQP4+), seronegative patient with idiopathic optic neuritis (AQP4-), and healthy volunteers (control). Anti-AQP4 antibody in a serum was measured by a previously established cell-based assay. The patients' sera were applied on the optic nerve after de-sheathed. Immunohistochemistry showed that at 7 days after the treatment, the area of the optic nerve exposed to the AQP4+ sera lost expression of both AQP4 and glial fibrillary acidic protein. Also, Human-IgG immunoreactivity and marked invasion of inflammation cells were observed in the optic nerve treated with AQP4+ serum. Immnoreactivity of neurofilament was reduced at 14 days after the treatment, not 7 days. Real-time polymerase chain reaction revealed the reduced gene expression of neurofilament in retina from the eye that was exposed to the AQP4+ sera at 14 days. Retrograde fluorogold-labeling on the retinal flatmount disclosed the significantly reduced number of retinal ganglion cells when the AQP4+ sera were applied. The present model has demonstrated that the sera from patients with seropositive NMOSDs led to the regional astrocytic degeneration and inflammatory cell invasion in the optic nerve, resulting in the ultimate loss of RGCs and their axons at areas beyond the injury site.

  3. Atomic force microscopy on plasma membranes from Xenopus laevis oocytes containing human aquaporin 4.

    PubMed

    Orsini, Francesco; Santacroce, Massimo; Cremona, Andrea; Gosvami, Nitya N; Lascialfari, Alessandro; Hoogenboom, Bart W

    2014-11-01

    Atomic force microscopy (AFM) is a unique tool for imaging membrane proteins in near-native environment (embedded in a membrane and in buffer solution) at ~1 nm spatial resolution. It has been most successful on membrane proteins reconstituted in 2D crystals and on some specialized and densely packed native membranes. Here, we report on AFM imaging of purified plasma membranes from Xenopus laevis oocytes, a commonly used system for the heterologous expression of membrane proteins. Isoform M23 of human aquaporin 4 (AQP4-M23) was expressed in the X. laevis oocytes following their injection with AQP4-M23 cRNA. AQP4-M23 expression and incorporation in the plasma membrane were confirmed by the changes in oocyte volume in response to applied osmotic gradients. Oocyte plasma membranes were then purified by ultracentrifugation on a discontinuous sucrose gradient, and the presence of AQP4-M23 proteins in the purified membranes was established by Western blotting analysis. Compared with membranes without over-expressed AQP4-M23, the membranes from AQP4-M23 cRNA injected oocytes showed clusters of structures with lateral size of about 10 nm in the AFM topography images, with a tendency to a fourfold symmetry as may be expected for higher-order arrays of AQP4-M23. In addition, but only infrequently, AQP4-M23 tetramers could be resolved in 2D arrays on top of the plasma membrane, in good quantitative agreement with transmission electron microscopy analysis and the current model of AQP4. Our results show the potential and the difficulties of AFM studies on cloned membrane proteins in native eukaryotic membranes.

  4. Adaptive Transition of Aquaporin 5 Expression and Localization during Preimplantation Embryo Development by In Vitro Culture.

    PubMed

    Park, Jae-Won; Shin, Yun Kyung; Choen, Yong-Pil

    2014-09-01

    Adaptive development of early stage embryo is well established and recently it is explored that the mammalian embryos also have adaptive ability to the stressful environment. However, the mechanisms are largely unknown. In this study, to evaluate the possible role of aquaporin in early embryo developmental adaptation, the expression of aquaporin (AQP) 5 gene which is detected during early development were examined by the environmental condition. To compare expression patterns between in vivo and in vitro, we conducted quantitative RT-PCR and analyzed localization of the AQP5 by whole mount immunofluorescence. At in vivo condition, Aqp5 expressed in oocyte and in all the stages of preimplantation embryo. It showed peak at 2-cell stage and decreased continuously until morula stage. At in vitro condition, Aqp5 expression pattern was similar with in vivo embryos. It expressed both at embryonic genome activation phase and second midpreimplantation gene activation phase, but the fold changes were modified between in vivo embryos and in vitro embryos. During in vivo development, AQP5 was mainly localized in apical membrane of blastomeres of 4-cell and 8-cell stage embryos, and then it was localized in cytoplasm. However, the main localization area of AQP5 was dramatically shifted after 8-cell stage from cytoplasm to nucleus by in vitro development. Those results explore the modification of Aqp5 expression levels and location of its final products by in vitro culture. It suggests that expression of Aqp5 and the roles of AQP5 in homeostasis can be modulated by in vitro culture, and that early stage embryos can develop successfully by themselves adapting to their condition through modulation of the specific gene expression and localization.

  5. Adaptive Transition of Aquaporin 5 Expression and Localization during Preimplantation Embryo Development by In Vitro Culture

    PubMed Central

    Park, Jae-Won; Shin, Yun Kyung; Choen, Yong-Pil

    2014-01-01

    Adaptive development of early stage embryo is well established and recently it is explored that the mammalian embryos also have adaptive ability to the stressful environment. However, the mechanisms are largely unknown. In this study, to evaluate the possible role of aquaporin in early embryo developmental adaptation, the expression of aquaporin (AQP) 5 gene which is detected during early development were examined by the environmental condition. To compare expression patterns between in vivo and in vitro, we conducted quantitative RT-PCR and analyzed localization of the AQP5 by whole mount immunofluorescence. At in vivo condition, Aqp5 expressed in oocyte and in all the stages of preimplantation embryo. It showed peak at 2-cell stage and decreased continuously until morula stage. At in vitro condition, Aqp5 expression pattern was similar with in vivo embryos. It expressed both at embryonic genome activation phase and second midpreimplantation gene activation phase, but the fold changes were modified between in vivo embryos and in vitro embryos. During in vivo development, AQP5 was mainly localized in apical membrane of blastomeres of 4-cell and 8-cell stage embryos, and then it was localized in cytoplasm. However, the main localization area of AQP5 was dramatically shifted after 8-cell stage from cytoplasm to nucleus by in vitro development. Those results explore the modification of Aqp5 expression levels and location of its final products by in vitro culture. It suggests that expression of Aqp5 and the roles of AQP5 in homeostasis can be modulated by in vitro culture, and that early stage embryos can develop successfully by themselves adapting to their condition through modulation of the specific gene expression and localization. PMID:25949184

  6. Aquaporin 5 Polymorphisms and Rate of Lung Function Decline in Chronic Obstructive Pulmonary Disease

    PubMed Central

    Hansel, Nadia N.; Sidhaye, Venkataramana; Rafaels, Nicholas M.; Gao, Li; Gao, Peisong; Williams, Renaldo; Connett, John E.; Beaty, Terri H.; Mathias, Rasika A.; Wise, Robert A.; King, Landon S.; Barnes, Kathleen C.

    2010-01-01

    Rationale Aquaporin-5 (AQP5) can cause mucus overproduction and lower lung function. Genetic variants in the AQP5 gene might be associated with rate of lung function decline in chronic obstructive pulmonary disease (COPD). Methods Five single nucleotide polymorphisms (SNPs) in AQP5 were genotyped in 429 European American individuals with COPD randomly selected from the NHLBI Lung Health Study. Mean annual decline in FEV1 % predicted, assessed over five years, was calculated as a linear regression slope, adjusting for potential covariates and stratified by smoking status. Constructs containing the wildtype allele and risk allele of the coding SNP N228K were generated using site-directed mutagenesis, and transfected into HBE-16 (human bronchial epithelial cell line). AQP5 abundance and localization were assessed by immunoblots and confocal immunofluoresence under control, shear stress and cigarette smoke extract (CSE 10%) exposed conditions to test for differential expression or localization. Results Among continuous smokers, three of the five SNPs tested showed significant associations (0.02>P>0.004) with rate of lung function decline; no associations were observed among the group of intermittent or former smokers. Haplotype tests revealed multiple association signals (0.012>P>0.0008) consistent with the single-SNP results. In HBE16 cells, shear stress and CSE led to a decrease in AQP5 abundance in the wild-type, but not in the N228K AQP5 plasmid. Conclusions Polymorphisms in AQP5 were associated with rate of lung function decline in continuous smokers with COPD. A missense mutation modulates AQP-5 expression in response to cigarette smoke extract and shear stress. These results suggest that AQP5 may be an important candidate gene for COPD. PMID:21151978

  7. Enlarged extracellular space of aquaporin-4-deficient mice does not enhance diffusion of Alexa Fluor 488 or dextran polymers

    PubMed Central

    Xiao, Fanrong; Hrabětová, Sabina

    2010-01-01

    Aquaporin-4 (AQP4) water channels expressed on glia have been implicated in maintaining the volume of extracellular space (ECS). A previous diffusion study employing small cation tetramethylammonium and real-time iontophoretic (RTI) method demonstrated an increase of about 25% in the ECS volume fraction (α) in the neocortex of AQP4−/− mice compared to AQP4+/+ mice but no change in the hindrance imposed to diffusing molecules (tortuosity λ). In contrast, other diffusion studies employing large molecules (dextran polymers) and fluorescence recovery after photobleaching (FRAP) method measured a decrease of about 10–20% in λ in the neocortex of AQP4−/− mice. These conflicting findings on λ would imply that large molecules diffuse more readily in the enlarged ECS of AQP4−/− mice than in wild type but small molecules do not. To test this hypothesis, we used integrative optical imaging (IOI) to measure tortuosity with a small Alexa Fluor 488 (MW 547, λAF) and two large dextran polymers (MW 3,000, λdex3 and MW 75,000, λdex75) in the in vitro neocortex of AQP4+/+ and AQP4−/− mice. We found that λAF = 1.59, λdex3 = 1.76 and λdex75 = 2.30 obtained in AQP4−/− mice were not significantly different from λAF = 1.61, λdex3 = 1.76, and λdex75 = 2.33 in AQP4+/+ mice. These IOI results demonstrate that λ measured with small and large molecules each remain unchanged in the enlarged ECS of AQP4−/− mice compared to values in AQP4+/+ mice. Further analysis suggests that the FRAP method yields diffusion parameters not directly comparable with those obtained by IOI or RTI methods. Our findings have implications for the role of glial AQP4 in maintaining the ECS structure. PMID:19303428

  8. Structural Alterations of Segmented Macular Inner Layers in Aquaporin4-Antibody-Positive Optic Neuritis Patients in a Chinese Population

    PubMed Central

    Peng, Chunxia; Wang, Wei; Xu, Quangang; Zhao, Shuo; Li, Hongyang; Yang, Mo; Cao, Shanshan; Zhou, Huanfen; Wei, Shihui

    2016-01-01

    Objectives This study aimed to analyse the structural injury of the peripapillary retinal nerve fibre layer (pRNFL) and segmented macular layers in optic neuritis (ON) in aquaporin4-antibody (AQP4-Ab) seropositivity(AQP4-Ab-positiveON) patients and in AQP4-Ab seronegativity (AQP4-Ab-negative ON) patients in order to evaluate their correlations with the best-corrected visual acuity (BCVA) and the value of the early diagnosis of neuromyelitis optica (NMO). Design This is a retrospective, cross-sectional and control observational study. Methods In total, 213 ON patients (291 eyes) and 50 healthy controls (HC) (100 eyes) were recruited in this study. According to a serum AQP4-Ab assay, 98 ON patients (132 eyes) were grouped as AQP4-Ab-positive ON and 115 ON patients (159 eyes) were grouped as AQP4-Ab-negative ON cohorts. All subjects underwent scanning with spectralis optical coherence tomography (OCT) and BCVA tests. pRNFL and segmented macular layer measurements were analysed. Results The pRNFL thickness in AQP4-Ab-positive ON eyes showed a more serious loss during 0–2 months (-27.61μm versus -14.47 μm) and ≥6 months (-57.91μm versus -47.19μm) when compared with AQP4-Ab-negative ON eyes. AQP4-Ab-positive ON preferentially damaged the nasal lateral pRNFL. The alterations in the macular ganglion cell layer plus the inner plexiform layer (GCIP) in AQP4-Ab-positive ON eyes were similar to those in AQP4-Ab-negative ON eyes. AQP4-Ab-positive ON eyes had entirely different injury patterns in the inner nuclear layer (INL) compared with AQP4-Ab-negative ON eyes during the first 6 months after the initial ON attack. These differences were as follows: the INL volume of AQP4-Ab-positive ON eyes had a gradual growing trend compared with AQP4-Ab-negative ON eyes, and it increased rapidly during 0–2 months, reached its peak during 2–4 months, and then decreased gradually. The pRNFL and GCIP in AQP4-Ab-positive ON eyes had positive correlations with BCVA. When the p

  9. Structural Determinants of Oligomerization of the Aquaporin-4 Channel.

    PubMed

    Kitchen, Philip; Conner, Matthew T; Bill, Roslyn M; Conner, Alex C

    2016-03-25

    The aquaporin (AQP) family of integral membrane protein channels mediate cellular water and solute flow. Although qualitative and quantitative differences in channel permeability, selectivity, subcellular localization, and trafficking responses have been observed for different members of the AQP family, the signature homotetrameric quaternary structure is conserved. Using a variety of biophysical techniques, we show that mutations to an intracellular loop (loop D) of human AQP4 reduce oligomerization. Non-tetrameric AQP4 mutants are unable to relocalize to the plasma membrane in response to changes in extracellular tonicity, despite equivalent constitutive surface expression levels and water permeability to wild-type AQP4. A network of AQP4 loop D hydrogen bonding interactions, identified using molecular dynamics simulations and based on a comparative mutagenic analysis of AQPs 1, 3, and 4, suggest that loop D interactions may provide a general structural framework for tetrameric assembly within the AQP family.

  10. Patterns of Antibody Binding to Aquaporin-4 Isoforms in Neuromyelitis Optica

    PubMed Central

    Mader, Simone; Lutterotti, Andreas; Di Pauli, Franziska; Kuenz, Bettina; Schanda, Kathrin; Aboul-Enein, Fahmy; Khalil, Michael; Storch, Maria K.; Jarius, Sven; Kristoferitsch, Wolfgang; Berger, Thomas; Reindl, Markus

    2010-01-01

    Background Neuromyelitis optica (NMO), a severe demyelinating disease, represents itself with optic neuritis and longitudinally extensive transverse myelitis. Serum NMO-IgG autoantibodies (Abs), a specific finding in NMO patients, target the water channel protein aquaporin-4 (AQP4), which is expressed as a long (M-1) or a short (M-23) isoform. Methodology/Principal Findings The aim of this study was to analyze serum samples from patients with NMO and controls for the presence and epitope specificity of IgG and IgM anti-AQP4 Abs using an immunofluorescence assay with HEK293 cells expressing M-1 or M-23 human AQP4. We included 56 patients with definite NMO (n = 30) and high risk NMO (n = 26), 101 patients with multiple sclerosis, 27 patients with clinically isolated syndromes (CIS), 30 patients with systemic lupus erythematosus (SLE) or Sjögren's syndrome, 29 patients with other neurological diseases and 47 healthy controls. Serum anti-AQP4 M-23 IgG Abs were specifically detected in 29 NMO patients, 17 patients with high risk NMO and two patients with myelitis due to demyelination (CIS) and SLE. In contrast, IgM anti-AQP4 Abs were not only found in some NMO and high risk patients, but also in controls. The sensitivity of the M-23 AQP4 IgG assay was 97% for NMO and 65% for high risk NMO, with a specificity of 100% compared to the controls. Sensitivity with M-1 AQP4 transfected cells was lower for NMO (70%) and high risk NMO (39%). The conformational epitopes of M-23 AQP4 are the primary targets of NMO-IgG Abs, whereas M-1 AQP4 Abs are developed with increasing disease duration and number of relapses. Conclusions Our results confirm M-23 AQP4-IgG Abs as reliable biomarkers in patients with NMO and high risk syndromes. M-1 and M-23 AQP4-IgG Abs are significantly associated with a higher number of relapses and longer disease duration. PMID:20463974

  11. Complement activating antibodies to myelin oligodendrocyte glycoprotein in neuromyelitis optica and related disorders

    PubMed Central

    2011-01-01

    Background Serum autoantibodies against the water channel aquaporin-4 (AQP4) are important diagnostic biomarkers and pathogenic factors for neuromyelitis optica (NMO). However, AQP4-IgG are absent in 5-40% of all NMO patients and the target of the autoimmune response in these patients is unknown. Since recent studies indicate that autoimmune responses to myelin oligodendrocyte glycoprotein (MOG) can induce an NMO-like disease in experimental animal models, we speculate that MOG might be an autoantigen in AQP4-IgG seronegative NMO. Although high-titer autoantibodies to human native MOG were mainly detected in a subgroup of pediatric acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS) patients, their role in NMO and High-risk NMO (HR-NMO; recurrent optic neuritis-rON or longitudinally extensive transverse myelitis-LETM) remains unresolved. Results We analyzed patients with definite NMO (n = 45), HR-NMO (n = 53), ADEM (n = 33), clinically isolated syndromes presenting with myelitis or optic neuritis (CIS, n = 32), MS (n = 71) and controls (n = 101; 24 other neurological diseases-OND, 27 systemic lupus erythematosus-SLE and 50 healthy subjects) for serum IgG to MOG and AQP4. Furthermore, we investigated whether these antibodies can mediate complement dependent cytotoxicity (CDC). AQP4-IgG was found in patients with NMO (n = 43, 96%), HR-NMO (n = 32, 60%) and in one CIS patient (3%), but was absent in ADEM, MS and controls. High-titer MOG-IgG was found in patients with ADEM (n = 14, 42%), NMO (n = 3, 7%), HR-NMO (n = 7, 13%, 5 rON and 2 LETM), CIS (n = 2, 6%), MS (n = 2, 3%) and controls (n = 3, 3%, two SLE and one OND). Two of the three MOG-IgG positive NMO patients and all seven MOG-IgG positive HR-NMO patients were negative for AQP4-IgG. Thus, MOG-IgG were found in both AQP4-IgG seronegative NMO patients and seven of 21 (33%) AQP4-IgG negative HR-NMO patients. Antibodies to MOG and AQP4 were predominantly of the IgG1 subtype, and were able to

  12. Enhanced expression levels of aquaporin-1 and aquaporin-4 in A549 cells exposed to silicon dioxide.

    PubMed

    Hao, Xiaohui; Wang, Hongli; Liu, Wei; Liu, Shupeng; Peng, Zihe; Sun, Yue; Zhao, Jinyuan; Jiang, Qiujie; Liu, Heliang

    2016-09-01

    Aquaporins (AQPs), water channel proteins in the cell membranes of mammals, have been reported to be important in maintaining the water balance of the respiratory system. However, little is known regarding the role of AQP in occupational pulmonary diseases such as silicosis. The present study investigated the expression of AQP1 and AQP4 in the human A549 alveolar epithelial cell line stimulated by silica (SiO2). A549 cells were cultured and divided into four groups: Control, SiO2‑stimulated, AQP1 inhibitor and AQP4 inhibitor. The cells of the SiO2‑stimulated group were stimulated with SiO2 dispersed suspension (50 mg/ml). The cells of the inhibitor group were pretreated with mercury (II) chloride (HgCl2; a specific channel inhibitor of AQP1) and 2‑(nicotinamide)‑1,3,4‑thiadiazole (TGN‑020; a specific channel inhibitor of AQP4) and stimulated with SiO2. The mRNA expression levels of AQP1 and AQP4 were detected by reverse transcription‑quantitative polymerase chain reaction, and the protein expression levels of AQP1 and AQP4 were detected by western blotting and immunocytochemistry. Compared with the control group, the expression levels of AQP1 and AQP4 mRNA and protein in SiO2‑stimulated groups increased and subsequently decreased (AQP1 peaked at 2 h and AQP4 at 1h; both P<0.001 compared with control group). In the inhibitor group, expression levels were increased compared with controls; however, they were significantly decreased compared with the SiO2‑stimulated group at 2 h (AQP1; P<0.001) and 1 h (AQP4; P<0.001). The expression of AQP1 and AQP4 increased when exposed to SiO2, and this was inhibited by HgCl2 and TGN‑020, suggesting that AQP1 and AQP4 may contribute to A549 cell damage induced by SiO2. AQP1 and AQP4 may thus be involved in the initiation and development of silicosis.

  13. Aquaporin 5 expression is frequent in prostate cancer and shows a dichotomous correlation with tumor phenotype and PSA recurrence.

    PubMed

    Pust, Alexandra; Kylies, Dominik; Hube-Magg, Claudia; Kluth, Martina; Minner, Sarah; Koop, Christina; Grob, Tobias; Graefen, Markus; Salomon, Georg; Tsourlakis, Maria Christina; Izbicki, Jakob; Wittmer, Corinna; Huland, Hartwig; Simon, Ronald; Wilczak, Waldemar; Sauter, Guido; Steurer, Stefan; Krech, Till; Schlomm, Thorsten; Melling, Nathaniel

    2016-02-01

    Aquaporin 5 (AQP5) is an androgen-regulated member of a family of small hydrophobic integral transmembrane water channel proteins regulating cellular water homeostasis and growth signaling. To evaluate its clinical impact and relationship with key genomic alterations in prostate cancer, AQP5 expression was analyzed by immunohistochemistry on a tissue microarray containing 12427 prostate cancers. The analysis revealed weak to moderate immunostaining in normal prostate epithelium. In prostate cancers AQP5 staining levels were more variable and also included completely negative and highly overexpressing cases. Negative, weak, moderate, and strong AQP5 staining was found in 25.0%, 32.5%, 32.5%, and 10.0% of 10239 interpretable tumors. Comparison of AQP5 expression levels with tumor characteristics showed a dichotomous pattern with both high and low staining levels being linked to unfavorable tumor phenotype. AQP5 was negative in 28%, 23%, 24%, and 35% of tumors with Gleason score ≤3 + 3, 3 + 4, 4 + 3 and ≥4 + 4, while the rate of strongly positive cases continuously increased from 7.0% over 10.0% and 12.0% to 13.0% in cancers with Gleason score ≤3 + 3, 3 + 4, 4 + 3 and ≥4 + 4. AQP5 expression was also related to ERG positivity and phosphatase and tensin homolog (PTEN) deletion (P < .0001 each). Strong AQP5 positivity was seen in 15.5% of ERG-positive and 5.8% of ERG-negative cancers (P < .0001) as well as in 14.7% of cancers with PTEN deletion and 9.4% of cancers without PTEN deletion. Remarkably, both negativity and strong positivity of AQP5 were linked to unfavorable disease outcome. This was however only seen in subgroups defined by TMPRSS2-ERG fusion and/or PTEN deletion. In summary, AQP5 can be both overexpressed and lost in subgroups of prostate cancers. Both alterations are linked to unfavorable outcome in molecularly defined cancer subgroups. It is hypothesized that this dichotomous role of AQP5 is due to two highly different mechanisms as to how the

  14. [Evolution of Devic's neuromyelitis optica spectrum disorders].

    PubMed

    Bernard-Valnet, Raphaël; Marignier, Romain

    2015-04-01

    Neuromyelitis optica (NMO) is a rare inflammatory disorder of the central nervous system affecting mostly the optic nerve and the spinal cord. These last few years have been characterized by a dramatic improvement of NMO knowledge and care. A unique feature of NMO is the presence of autoantibodies directed against aquaporin-4 (AQP4-Ab). Identification of this biomarker has enlarged the clinical spectrum of the disease to a broad variety of symptoms and syndromes including brain, brainstem and hypothalamus involvement. This modifies the acknowledged definition of NMO, switching from a clinical phenotype to a biological one and introducing the concept of "aquaporinopathy" or "autoimmune AQP4 channelopathy". AQP4-Ab plays an important role in NMO pathophysiology. In vitro and ex vivo experiments showed that AQP4-Ab can induce either direct astrocyte loss through complement activation (neuroinflammation) or astrocyte changes via internalization of AQP4 (neuromodulation). Recently, T cell involvement in NMO has been suggested. Based on relatively small retrospective and prospective case series, several treatments appear to be likely effective in preventing attacks and stabilizing disability in NMO patients. Relapse prevention in NMO is based on early and maintenance immunosuppressive treatments. Considering the antibody-driven hypothesis, treatment should target B-cells. MS-approved therapies are not currently recommended for NMO patients, several series suggesting poor efficacy or harmful effects. Despite recent improvement of the detection method, some patients remain seronegative for AQP4-Ab. This group expresses specific demographic and disease-related features different for AQP4-Ab positive ones. This raises the question of the place of seronegative AQP4-Ab NMO patients in the spectrum, of their intimate physiopathology and finally of the therapeutic strategy to adopt in such patients.

  15. Role of autoantibodies in acquired inflammatory demyelinating diseases of the central nervous system in children.

    PubMed

    Rostasy, Kevin; Reindl, Markus

    2013-12-01

    The recent detection of aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) autoantibodies in acquired inflammatory demyelinating diseases, such as neuromyelitis optica, or acute disseminated encephalomyelitis, and multiple sclerosis, in children strongly indicates that B-cell-dependent mechanisms contribute to the pathogenesis. This review aims to give an overview of the role of autoantibodies in inflammatory demyelinating pediatric diseases, with a focus on antibodies to AQP4 and MOG.

  16. Absence of aquaporin-4 in skeletal muscle alters proteins involved in bioenergetic pathways and calcium handling.

    PubMed

    Basco, Davide; Nicchia, Grazia Paola; D'Alessandro, Angelo; Zolla, Lello; Svelto, Maria; Frigeri, Antonio

    2011-04-28

    Aquaporin-4 (AQP4) is a water channel expressed at the sarcolemma of fast-twitch skeletal muscle fibers, whose expression is altered in several forms of muscular dystrophies. However, little is known concerning the physiological role of AQP4 in skeletal muscle and its functional and structural interaction with skeletal muscle proteome. Using AQP4-null mice, we analyzed the effect of the absence of AQP4 on the morphology and protein composition of sarcolemma as well as on the whole skeletal muscle proteome. Immunofluorescence analysis showed that the absence of AQP4 did not perturb the expression and cellular localization of the dystrophin-glycoprotein complex proteins, aside from those belonging to the extracellular matrix, and no alteration was found in sarcolemma integrity by dye extravasation assay. With the use of a 2DE-approach (BN/SDS-PAGE), protein maps revealed that in quadriceps, out of 300 Coomassie-blue detected and matched spots, 19 proteins exhibited changed expression in AQP4(-/-) compared to WT mice. In particular, comparison of the protein profiles revealed 12 up- and 7 down-regulated protein spots in AQP4-/- muscle. Protein identification by MS revealed that the perturbed expression pattern belongs to proteins involved in energy metabolism (i.e. GAPDH, creatine kinase), as well as in Ca(2+) handling (i.e. parvalbumin, SERCA1). Western blot analysis, performed on some significantly changed proteins, validated the 2D results. Together these findings suggest AQP4 as a novel determinant in the regulation of skeletal muscle metabolism and better define the role of this water channel in skeletal muscle physiology.

  17. Absence of Aquaporin-4 in Skeletal Muscle Alters Proteins Involved in Bioenergetic Pathways and Calcium Handling

    PubMed Central

    Basco, Davide; Nicchia, Grazia Paola; D'Alessandro, Angelo; Zolla, Lello; Svelto, Maria; Frigeri, Antonio

    2011-01-01

    Aquaporin-4 (AQP4) is a water channel expressed at the sarcolemma of fast-twitch skeletal muscle fibers, whose expression is altered in several forms of muscular dystrophies. However, little is known concerning the physiological role of AQP4 in skeletal muscle and its functional and structural interaction with skeletal muscle proteome. Using AQP4-null mice, we analyzed the effect of the absence of AQP4 on the morphology and protein composition of sarcolemma as well as on the whole skeletal muscle proteome. Immunofluorescence analysis showed that the absence of AQP4 did not perturb the expression and cellular localization of the dystrophin-glycoprotein complex proteins, aside from those belonging to the extracellular matrix, and no alteration was found in sarcolemma integrity by dye extravasation assay. With the use of a 2DE-approach (BN/SDS-PAGE), protein maps revealed that in quadriceps, out of 300 Coomassie-blue detected and matched spots, 19 proteins exhibited changed expression in AQP4−/− compared to WT mice. In particular, comparison of the protein profiles revealed 12 up- and 7 down-regulated protein spots in AQP4−/− muscle. Protein identification by MS revealed that the perturbed expression pattern belongs to proteins involved in energy metabolism (i.e. GAPDH, creatine kinase), as well as in Ca2+ handling (i.e. parvalbumin, SERCA1). Western blot analysis, performed on some significantly changed proteins, validated the 2D results. Together these findings suggest AQP4 as a novel determinant in the regulation of skeletal muscle metabolism and better define the role of this water channel in skeletal muscle physiology. PMID:21552523

  18. Aquaporin-4-dependent K(+) and water transport modeled in brain extracellular space following neuroexcitation.

    PubMed

    Jin, Byung-Ju; Zhang, Hua; Binder, Devin K; Verkman, A S

    2013-01-01

    Potassium (K(+)) ions released into brain extracellular space (ECS) during neuroexcitation are efficiently taken up by astrocytes. Deletion of astrocyte water channel aquaporin-4 (AQP4) in mice alters neuroexcitation by reducing ECS [K(+)] accumulation and slowing K(+) reuptake. These effects could involve AQP4-dependent: (a) K(+) permeability, (b) resting ECS volume, (c) ECS contraction during K(+) reuptake, and (d) diffusion-limited water/K(+) transport coupling. To investigate the role of these mechanisms, we compared experimental data to predictions of a model of K(+) and water uptake into astrocytes after neuronal release of K(+) into the ECS. The model computed the kinetics of ECS [K(+)] and volume, with input parameters including initial ECS volume, astrocyte K(+) conductance and water permeability, and diffusion in astrocyte cytoplasm. Numerical methods were developed to compute transport and diffusion for a nonstationary astrocyte-ECS interface. The modeling showed that mechanisms b-d, together, can predict experimentally observed impairment in K(+) reuptake from the ECS in AQP4 deficiency, as well as altered K(+) accumulation in the ECS after neuroexcitation, provided that astrocyte water permeability is sufficiently reduced in AQP4 deficiency and that solute diffusion in astrocyte cytoplasm is sufficiently low. The modeling thus provides a potential explanation for AQP4-dependent K(+)/water coupling in the ECS without requiring AQP4-dependent astrocyte K(+) permeability. Our model links the physical and ion/water transport properties of brain cells with the dynamics of neuroexcitation, and supports the conclusion that reduced AQP4-dependent water transport is responsible for defective neuroexcitation in AQP4 deficiency.

  19. Myasthenia gravis and neuromyelitis optica spectrum disorder

    PubMed Central

    Leite, M.I.; Coutinho, E.; Lana-Peixoto, M.; Apostolos, S.; Waters, P.; Sato, D.; Melamud, L.; Marta, M.; Graham, A.; Spillane, J.; Villa, A.M.; Callegaro, D.; Santos, E.; da Silva, A. Martins; Jarius, S.; Howard, R.; Nakashima, I.; Giovannoni, G.; Buckley, C.; Hilton-Jones, D.; Vincent, A.

    2012-01-01

    Objective: To describe 16 patients with a coincidence of 2 rare diseases: aquaporin-4 antibody (AQP4-Ab)–mediated neuromyelitis optica spectrum disorder (AQP4-NMOSD) and acetylcholine receptor antibody (AChR-Ab)–mediated myasthenia gravis (AChR-MG). Methods: The clinical details and antibody results of 16 patients with AChR-MG and AQP4-NMOSD were analyzed retrospectively. Results: All had early-onset AChR-MG, the majority with mild generalized disease, and a high proportion achieved remission. Fifteen were female; 11 were Caucasian. In 14/16, the MG preceded NMOSD (median interval: 16 years) and 11 of these had had a thymectomy although 1 only after NMOSD onset. In 4/5 patients tested, AQP4-Abs were detectable between 4 and 16 years prior to disease onset, including 2 patients with detectable AQP4-Abs prior to thymectomy. AChR-Abs decreased and the AQP4-Ab levels increased over time in concordance with the relevant disease. AChR-Abs were detectable at NMOSD onset in the one sample available from 1 of the 2 patients with NMOSD before MG. Conclusions: Although both conditions are rare, the association of MG and NMOSD occurs much more frequently than by chance and the MG appears to follow a benign course. AChR-Abs or AQP4-Abs may be present years before onset of the relevant disease and the antibody titers against AQP4 and AChR tend to change in opposite directions. Although most cases had MG prior to NMOSD onset, and had undergone thymectomy, NMOSD can occur first and in patients who have not had their thymus removed. PMID:22551731

  20. Water Permeability of Aquaporin-4 Channel Depends on Bilayer Composition, Thickness, and Elasticity

    PubMed Central

    Tong, Jihong; Briggs, Margaret M.; McIntosh, Thomas J.

    2012-01-01

    Aquaporin-4 (AQP4) is the primary water channel in the mammalian brain, particularly abundant in astrocytes, whose plasma membranes normally contain high concentrations of cholesterol. Here we test the hypothesis that the water permeabilities of two naturally occurring isoforms (AQP4-M1 and AQP4-M23) depend on bilayer mechanical/structural properties modulated by cholesterol and phospholipid composition. Osmotic stress measurements were performed with proteoliposomes containing AQP4 and three different lipid mixtures: 1), phosphatidylcholine (PC) and phosphatidylglycerol (PG); 2), PC, PG, with 40 mol % cholesterol; and 3), sphingomyelin (SM), PG, with 40 mol % cholesterol. The unit permeabilities of AQP4-M1 were 3.3 ± 0.4 × 10−13 cm3/s (mean ± SE), 1.2 ± 0.1 × 10−13 cm3/s, and 0.4 ± 0.1 × 10−13 cm3/s in PC:PG, PC:PG:cholesterol, and SM:PG:cholesterol, respectively. The unit permeabilities of AQP4-M23 were 2.1 ± 0.2 × 10−13 cm3/s, 0.8 ± 0.1 × 10−13 cm3/s, and 0.3 ± 0.1 × 10−13 cm3/s in PC:PG, PC:PG:cholesterol, and SM:PG:cholesterol, respectively. Thus, for each isoform the unit permeabilities strongly depended on bilayer composition and systematically decreased with increasing bilayer compressibility modulus and bilayer thickness. These observations suggest that altering lipid environment provides a means of regulating water channel permeability. Such permeability changes could have physiological consequences, because AQP4 water permeability would be reduced by its sequestration into SM:cholesterol-enriched raft microdomains. Conversely, under ischemic conditions astrocyte membrane cholesterol content decreases, which could increase AQP4 permeability. PMID:23199918

  1. Water permeability of aquaporin-4 channel depends on bilayer composition, thickness, and elasticity.

    PubMed

    Tong, Jihong; Briggs, Margaret M; McIntosh, Thomas J

    2012-11-07

    Aquaporin-4 (AQP4) is the primary water channel in the mammalian brain, particularly abundant in astrocytes, whose plasma membranes normally contain high concentrations of cholesterol. Here we test the hypothesis that the water permeabilities of two naturally occurring isoforms (AQP4-M1 and AQP4-M23) depend on bilayer mechanical/structural properties modulated by cholesterol and phospholipid composition. Osmotic stress measurements were performed with proteoliposomes containing AQP4 and three different lipid mixtures: 1), phosphatidylcholine (PC) and phosphatidylglycerol (PG); 2), PC, PG, with 40 mol % cholesterol; and 3), sphingomyelin (SM), PG, with 40 mol % cholesterol. The unit permeabilities of AQP4-M1 were 3.3 ± 0.4 × 10(-13) cm(3)/s (mean ± SE), 1.2 ± 0.1 × 10(-13) cm(3)/s, and 0.4 ± 0.1 × 10(-13) cm(3)/s in PC:PG, PC:PG:cholesterol, and SM:PG:cholesterol, respectively. The unit permeabilities of AQP4-M23 were 2.1 ± 0.2 × 10(-13) cm(3)/s, 0.8 ± 0.1 × 10(-13) cm(3)/s, and 0.3 ± 0.1 × 10(-13) cm(3)/s in PC:PG, PC:PG:cholesterol, and SM:PG:cholesterol, respectively. Thus, for each isoform the unit permeabilities strongly depended on bilayer composition and systematically decreased with increasing bilayer compressibility modulus and bilayer thickness. These observations suggest that altering lipid environment provides a means of regulating water channel permeability. Such permeability changes could have physiological consequences, because AQP4 water permeability would be reduced by its sequestration into SM:cholesterol-enriched raft microdomains. Conversely, under ischemic conditions astrocyte membrane cholesterol content decreases, which could increase AQP4 permeability.

  2. Hypertonic saline reduces lipopolysaccharide-induced mouse brain edema through inhibiting aquaporin 4 expression

    PubMed Central

    2012-01-01

    Introduction Three percent sodium chloride (NaCl) treatment has been shown to reduce brain edema and inhibited brain aquaporin 4 (AQP4) expression in bacterial meningitis induced by Escherichia coli. Lipopolysaccharide (LPS) is the main pathogenic component of E. coli. We aimed to explore the effect of 3% NaCl in mouse brain edema induced by LPS, as well as to elucidate the potential mechanisms of action. Methods Three percent NaCl was used to treat cerebral edema induced by LPS in mice in vivo. Brain water content, IL-1β, TNFα, immunoglobulin G (IgG), AQP4 mRNA and protein were measured in brain tissues. IL-1β, 3% NaCl and calphostin C (a specific inhibitor of protein kinase C) were used to treat the primary astrocytes in vitro. AQP4 mRNA and protein were measured in astrocytes. Differences in various groups were determined by one-way analysis of variance. Results Three percent NaCl attenuated the increase of brain water content, IL-1β, TNFα, IgG, AQP4 mRNA and protein in brain tissues induced by LPS. Three percent NaCl inhibited the increase of AQP4 mRNA and protein in astrocytes induced by IL-1β in vitro. Calphostin C blocked the decrease of AQP4 mRNA and protein in astrocytes induced by 3% NaCl in vitro. Conclusions Osmotherapy with 3% NaCl ameliorated LPS-induced cerebral edema in vivo. In addition to its osmotic force, 3% NaCl exerted anti-edema effects possibly through down-regulating the expression of proinflammatory cytokines (IL-1β and TNFα) and inhibiting the expression of AQP4 induced by proinflammatory cytokines. Three percent NaCl attenuated the expression of AQP4 through activation of protein kinase C in astrocytes. PMID:23036239

  3. TNF-α inhibits aquaporin 5 expression in human salivary gland acinar cells via suppression of histone H4 acetylation.

    PubMed

    Yamamura, Yoshiko; Motegi, Katsumi; Kani, Kouichi; Takano, Hideyuki; Momota, Yukihiro; Aota, Keiko; Yamanoi, Tomoko; Azuma, Masayuki

    2012-08-01

    Sjögren's syndrome is a systemic autoimmune disease characterized by reductions in salivary and lacrimal secretions. The mechanisms underlying these reductions remain unclear. We have previously shown that TNF-α plays an important role in the destruction of acinar structures. Here we examined TNF-α's function in the expression of aquaporin (AQP) 5 in human salivary gland acinar cells. Immortalized human salivary gland acinar (NS-SV-AC) cells were treated with TNF-α, and then the expression levels of AQP5 mRNA and protein were analysed. In addition, the mechanisms underlying the reduction of AQP5 expression by TNF-α treatment were investigated. TNF-α-treatment of NS-SV-AC cells significantly suppressed the expression levels of AQP5 mRNA and protein, and reduced the net fluid secretion rate. We examined the expression and activation levels of DNA methyltransferases (Dnmts) in NS-SV-AC cells treated with TNF-α. However, no significant changes were observed in the expression or activation levels of Dnmt1, Dnmt3a or Dnmt3b. Although we also investigated the role of NF-κB activity in the TNF-α-induced suppression of AQP5 expression in NS-SV-AC cells, we detected similar TNF-α suppression of AQP5 expression in non-transfected cells and in a super-repressor form of IκBα cDNA-transfected cell clones. However, interestingly, chromatin immunoprecipitation analysis demonstrated a remarkable decrease in levels of acetylated histone H4 associated with the AQP5 gene promoter after treatment with TNF-α in NS-SV-AC cells. Therefore, our results may indicate that TNF-α inhibition of AQP5 expression in human salivary gland acinar cells is due to the epigenetic mechanism by suppression of acetylation of histone H4.

  4. An immunoassay that distinguishes real neuromyelitis optica signals from a labeling detected in patients receiving natalizumab

    PubMed Central

    2014-01-01

    Background Cell-based assays for neuromyelitis optica (NMO) diagnosis are the most sensitive and specific methods to detect anti-aquaporin 4 (AQP4) antibodies in serum, but some improvements in their quantitative and specificity capacities would be desirable. Thus the aim of the present work was to develop a sensitive quantitative method for detection of anti-AQP4 antibodies that allows clear diagnosis of NMO and distinction of false labeling produced by natalizumab treatment. Methods Sera from 167 individuals, patients diagnosed with NMO (16), multiple sclerosis (85), optic neuritis (24), idiopathic myelitis (21), or other neurological disorders (13) and healthy controls (8), were used as the primary antibody in an immunofluorescence assay on HEK cells transfected with the M23 isoform of human AQP4 fused with enhanced green fluorescent protein. Cells used were freshly transfected or stored frozen and then thawed just before adding the serum. Results Microscopic observation and fluorescence quantification produced similar results in fresh and frozen samples. Serum samples from patients diagnosed with NMO were 100% positive for anti-AQP4 antibodies, while all the other sera were negative. Using serum from patients treated with natalizumab, a small and unspecific fluorescent signal was produced from all HEK cells, regardless of AQP4 expression. Conclusions Our cell-based double-label fluorescence immunoassay protocol significantly increases the signal specificity and reduces false diagnosis of NMO patients, especially in those receiving natalizumab treatment. Frozen pretreated cells allow faster detection of anti-AQP4 antibodies. PMID:24980919

  5. Translational regulation mechanisms of aquaporin-4 supramolecular organization in astrocytes.

    PubMed

    Pisani, Francesco; Rossi, Andrea; Nicchia, Grazia Paola; Svelto, Maria; Frigeri, Antonio

    2011-12-01

    The two predominant isoforms of Aquaporin-4 (AQP4), AQP4-M23 and AQP4-M1, assemble in the plasma membrane to form supramolecular structures called Orthogonal Array of Particles (OAPs) whose dimension is tightly associated to the M1/M23 ratio. Here, we explore translational regulation contribution to M1/M23 expression in primary cultures of rat astrocytes, and analyze the role of M1 mRNA 5'untranslated region (5'UTR) in this mechanism. Using isoform-specific RNAi we found that in rat astrocytes primary cultures a large proportion of M23 protein derives from M1 mRNA translation. Furthermore, site-specific mutagenesis of the 5'UTR sequence of AQP4-M1 mRNA indicates that a multiple-site leaky scanning mechanism, an out-of-frame upstream ORF (uORF), and a reinitiation mechanism are able to modulate the M1/M23 ratio and consequently, OAPs formation. These mechanisms are likely to be shared by different species, including human, and they can also be assumed to play a role in those pathophysiological situations where the organization of AQP4 in supramolecular structures (OAPs) is involved. Finally, we report that, when transfected in Hela cells, the longer rat AQP4 isoform, called Mz, which is not present in human impairs OAPs formation.

  6. Structure and functions of aquaporin-4-based orthogonal arrays of particles.

    PubMed

    Wolburg, Hartwig; Wolburg-Buchholz, Karen; Fallier-Becker, Petra; Noell, Susan; Mack, Andreas F

    2011-01-01

    Orthogonal arrays or assemblies of intramembranous particles (OAPs) are structures in the membrane of diverse cells which were initially discovered by means of the freeze-fracturing technique. This technique, developed in the 1960s, was important for the acceptance of the fluid mosaic model of the biological membrane. OAPs were first described in liver cells, and then in parietal cells of the stomach, and most importantly, in the astrocytes of the brain. Since the discovery of the structure of OAPs and the identification of OAPs as the morphological equivalent of the water channel protein aquaporin-4 (AQP4) in the 1990s, a plethora of morphological work on OAPs in different cells was published. Now, we feel a need to balance new and old data on OAPs and AQP4 to elucidate the interrelationship of both structures and molecules. In this review, the identity of OAPs as AQP4-based structures in a diversity of cells will be described. At the same time, arguments are offered that under pathological or experimental circumstances, AQP4 can also be expressed in a non-OAP form. Thus, we attempt to project classical work on OAPs onto the molecular biology of AQP4. In particular, astrocytes and glioma cells will play the major part in this review, not only due to our own work but also due to the fact that most studies on structure and function of AQP4 were done in the nervous system.

  7. Immunohistochemical examination of intracerebral aquaporin-4 expression and its application for differential diagnosis between freshwater and saltwater drowning.

    PubMed

    An, Jun-Ling; Ishida, Yuko; Kimura, Akihiko; Kondo, Toshikazu

    2011-01-01

    Human brain samples were collected from 70 autopsy cases including 22 freshwater drowning (FWD), 26 saltwater drowning (SWD), and 22 non-drowning cases as controls. Then, immunohistochemical study combined with morphometry was carried out in order to examine the differential expression of AQP1 and AQP4 in the brain samples. Immunohistochemically, star-shaped cells bearing highly branched processes, often surrounding blood vessels, showed positive reactions for AQP1 and AQP4 in FWD, SWD, as well as control groups. Additionally, with double-color immunofluorescence analysis, AQP1- or AQP4-positive cells could be identified as GFAP-positive astrocytes. Moreover, AQP1-positive reaction was also observed in blood vessels. Morphometrically, there were no significant differences in AQP1 expression in astrocytes or in blood vessels among the three groups. In contrast, the average value of AQP4-positive astrocytes was significantly higher in FWD cases than in SWD and control groups. Moreover, AQP4 expression was significantly lower in SWD than in the control group (p < 0.05). Moreover, there was no significant correlation between post-submerged interval and AQP expression in drowning cases. Therefore, immunohistochemical analysis of intracerebral AQP4 expression would be forensically useful for differentiation between FWD and SWD.

  8. Overactivation of corticotropin-releasing factor receptor type 1 and aquaporin-4 by hypoxia induces cerebral edema

    PubMed Central

    Chen, Shao-Jun; Yang, Jia-Fang; Kong, Fan-Ping; Ren, Ji-Long; Hao, Ke; Li, Min; Yuan, Yuan; Chen, Xin-Can; Yu, Ri-Sheng; Li, Jun-Fa; Leng, Gareth; Chen, Xue-Qun; Du, Ji-Zeng

    2014-01-01

    Cerebral edema is a potentially life-threatening illness, but knowledge of its underlying mechanisms is limited. Here we report that hypobaric hypoxia induces rat cerebral edema and neuronal apoptosis and increases the expression of corticotrophin releasing factor (CRF), CRF receptor type 1 (CRFR1), aquaporin-4 (AQP4), and endothelin-1 (ET-1) in the cortex. These effects, except for the increased expression of CRF itself, could all be blocked by pretreatment with an antagonist of the CRF receptor CRFR1. We also show that, in cultured primary astrocytes: (i) both CRFR1 and AQP4 are expressed; (ii) exogenous CRF, acting through CRFR1, triggers signaling of cAMP/PKA, intracellular Ca2+, and PKCε; and (iii) the up-regulated cAMP/PKA signaling contributes to the phosphorylation and expression of AQP4 to enhance water influx into astrocytes and produces an up-regulation of ET-1 expression. Finally, using CHO cells transfected with CRFR1+ and AQP4+, we show that transfected CRFR1+ contributes to edema via transfected AQP4+. In conclusion, hypoxia triggers cortical release of CRF, which acts on CRFR1 to trigger signaling of cAMP/PKA in cortical astrocytes, leading to activation of AQP4 and cerebral edema. PMID:25146699

  9. Mechanisms of Astrocyte-Mediated Cerebral Edema

    PubMed Central

    Stokum, Jesse A.; Kurland, David B.; Gerzanich, Volodymyr; Simard, J. Marc

    2014-01-01

    Cerebral edema formation stems from disruption of blood brain barrier (BBB) integrity and occurs after injury to the CNS. Due to the restrictive skull, relatively small increases in brain volume can translate into impaired tissue perfusion and brain herniation. In excess, cerebral edema can be gravely harmful. Astrocytes are key participants in cerebral edema by virtue of their relationship with the cerebral vasculature, their unique compliment of solute and water transport proteins, and their general role in brain volume homeostasis. Following the discovery of aquaporins, passive conduits of water flow, aquaporin 4 (AQP4) was identified as the predominant astrocyte water channel. Normally, AQP4 is highly enriched at perivascular endfeet, the outermost layer of the BBB, whereas after injury, AQP4 expression disseminates to the entire astrocytic plasmalemma, a phenomenon termed dysregulation. Arguably, the most important role of AQP4 is to rapidly neutralize osmotic gradients generated by ionic transporters. In pathological conditions, AQP4 is believed to be intimately involved in the formation and clearance of cerebral edema. In this review, we discuss aquaporin function and localization in the BBB during health and injury, and we examine post-injury ionic events that modulate AQP4- dependent edema formation. PMID:24996934

  10. Deletion of aquaporin-4 increases extracellular K(+) concentration during synaptic stimulation in mouse hippocampus.

    PubMed

    Haj-Yasein, Nadia Nabil; Bugge, Cecilie Elisabeth; Jensen, Vidar; Østby, Ivar; Ottersen, Ole Petter; Hvalby, Øivind; Nagelhus, Erlend Arnulf

    2015-07-01

    The coupling between the water channel aquaporin-4 (AQP4) and K(+) transport has attracted much interest. In this study, we assessed the effect of Aqp4 deletion on activity-induced [K(+)]o changes in acute slices from hippocampus and corpus callosum of adult mice. We show that Aqp4 deletion has a layer-specific effect on [K(+)]o that precisely mirrors the known effect on extracellular volume dynamics. In CA1, the peak [K(+)]o in stratum radiatum during 20 Hz stimulation of Schaffer collateral/commissural fibers was significantly higher in Aqp4 (-/-) mice than in wild types, whereas no differences were observed throughout the [K(+)]o recovery phase. In stratum pyramidale and corpus callosum, neither peak [K(+)]o nor post-stimulus [K(+)]o recovery was affected by Aqp4 deletion. Our data suggest that AQP4 modulates [K(+)]o during synaptic stimulation through its effect on extracellular space volume.

  11. Quantitation of brain edema and localisation of aquaporin 4 expression in relation to susceptibility to experimental cerebral malaria.

    PubMed

    Ampawong, Sumate; Combes, Valéry; Hunt, Nicholas H; Radford, Jane; Chan-Ling, Tailoi; Pongponratn, Emsri; Grau, Georges E R

    2011-08-15

    The pathogenic mechanisms underlying the occurrence of cerebral malaria (CM) are still incompletely understood but, clearly, cerebral complications may result from concomitant microvessel obstruction and inflammation. The extent to which brain edema contributes to pathology has not been investigated. Using the model of P. berghei ANKA infection, we compared brain microvessel morphology of CM-susceptible and CM-resistant mice. By quantitative planimetry, we provide evidence that CM is characterized by enlarged perivascular spaces (PVS). We show a dramatic aquaporin 4 (AQP4) upregulation, selectively at the level of astrocytic foot processes, in both CM and non-CM disease, but significantly more pronounced in mice with malarial-induced neurological syndrome. This suggests that a threshold of AQP4 expression is needed to lead to neurovascular pathology, a view that is supported by significantly higher levels in mice with clinically overt CM. Numbers of intravascular leukocytes significantly correlated with both PVS enlargement and AQP4 overexpression. Thus, brain edema could be a contributing factor in CM pathogenesis and AQP4, specifically in its astrocytic location, a key molecule in this mechanism. Since experimental CM is associated with substantial brain edema, it models paediatric CM better than the adult syndrome and it is tempting to evaluate AQP4 in the former context. If AQP4 changes are confirmed in human CM, it may represent a novel target for therapeutic intervention.

  12. Design and optimization of an active magnetic thrust bearing for flyhweel energy storage systems

    NASA Astrophysics Data System (ADS)

    Lam, Siu Kiong

    2011-12-01

    This thesis is motivated in part by the lack of published research pertaining to active magnetic thrust bearings (AMTB), as compared to active magnetic radial bearings (AMRB). This thesis presents one method in implementing AMTBs to provide a near frictionless support to a rotor contained in a vacuum environment, mitigating the concerns of viscous drag and chemical reaction as a result of the exposure to lubricants. An analytical model was first developed to linearize the AMTB against a predefined operating point. A finite element simulation was subsequently conducted to verify the analytical model. The analytical and finite element methods both indicated that the steady state power consumption of the AMTB was approximately 12 W, and there was no occurrence of magnetic saturation within the material. The stress analysis showed that the stresses experienced by the rotor part of the AMTB as it rotated at the maximum rotation speed were well below the yield stress of the material. Lastly, a closed loop feedback network with proportional-integral-derivative (PID) controllers was designed and implemented as the control scheme for keeping the flywheel rotor at a predefined axial position, while the rotor underwent axial position variations due to the external disturbance, thermal expansion, or Poisson contraction effects. The resulting simulations showed that the PID controller was able to stabilize the flywheel rotor 0.3 s after it was disturbed by an external force equaling 10% of its weight.

  13. Aquaporin 5 regulates cigarette smoke induced emphysema by modulating barrier and immune properties of the epithelium.

    PubMed

    Aggarwal, Neil R; Chau, Eric; Garibaldi, Brian T; Mock, Jason R; Sussan, Thomas; Rao, Keshav; Rao, Kaavya; Menon, Anil G; D'Alessio, Franco R; Damarla, Mahendra; Biswal, Shyam; King, Landon S; Sidhaye, Venkataramana K

    2013-10-01

    Chronic obstructive pulmonary disease (COPD) causes significant morbidity and mortality. Cigarette smoke, the most common risk factor for COPD, induces airway and alveolar epithelial barrier permeability and initiates an innate immune response. Changes in abundance of aquaporin 5 (AQP5), a water channel, can affect epithelial permeability and immune response after cigarette smoke exposure. To determine how AQP5-derived epithelial barrier modulation affects epithelial immune response to cigarette smoke and development of emphysema, WT and AQP5(-/-) mice were exposed to cigarette smoke (CS). We measured alveolar cell counts and differentials, and assessed histology, mean-linear intercept (MLI), and surface-to-volume ratio (S/V) to determine severity of emphysema. We quantified epithelial-derived signaling proteins for neutrophil trafficking, and manipulated AQP5 levels in an alveolar epithelial cell line to determine specific effects on neutrophil transmigration after CS exposure. We assessed paracellular permeability and epithelial turnover in response to CS. In contrast to WT mice, AQP5(-/-) mice exposed to 6 months of CS did not demonstrate a significant increase in MLI or a significant decrease in S/V compared with air-exposed mice, conferring protection against emphysema. After sub-acute (4 weeks) and chronic (6 mo) CS exposure, AQP5(-/-) mice had fewer alveolar neutrophil but similar lung neutrophil numbers as WT mice. The presence of AQP5 in A549 cells, an alveolar epithelial cell line, was associated with increase neutrophil migration after CS exposure. Compared with CS-exposed WT mice, neutrophil ligand (CD11b) and epithelial receptor (ICAM-1) expression were reduced in CS-exposed AQP5(-/-) mice, as was secreted LPS-induced chemokine (LIX), an epithelial-derived neutrophil chemoattractant. CS-exposed AQP5(-/-) mice demonstrated decreased type I pneumocytes and increased type II pneumocytes compared with CS-exposed WT mice suggestive of enhanced epithelial

  14. Current concept of neuromyelitis optica (NMO) and NMO spectrum disorders.

    PubMed

    Jacob, Anu; McKeon, Andrew; Nakashima, Ichiro; Sato, Douglas Kazutoshi; Elsone, Liene; Fujihara, Kazuo; de Seze, Jerome

    2013-08-01

    Neuromyelitis optica (NMO) has been described as a disease clinically characterised by severe optic neuritis (ON) and transverse myelitis (TM). Other features of NMO include female preponderance, longitudinally extensive spinal cord lesions (>3 vertebral segments), and absence of oligoclonal IgG bands . In spite of these differences from multiple sclerosis (MS), the relationship between NMO and MS has long been controversial. However, since the discovery of NMO-IgG or aquaporin-4 (AQP4) antibody (AQP4-antibody), an NMO-specific autoantibody to AQP4, the dominant water channel in the central nervous system densely expressed on end-feet of astrocytes, unique clinical features, MRI and other laboratory findings in NMO have been clarified further. AQP4-antibody is now the most important laboratory finding for the diagnosis of NMO. Apart from NMO, some patients with recurrent ON or recurrent longitudinally extensive myelitis alone are also often positive for AQP4-antibody. Moreover, studies of AQP4-antibody-positive patients have revealed that brain lesions are not uncommon in NMO, and some patterns appear to be unique to NMO. Thus, the spectrum of NMO is wider than mere ON and TM. Pathological analyses of autopsied cases strongly suggest that unlike MS, astrocytic damage is the primary pathology in NMO, and experimental studies confirm the pathogenicity of AQP4-antibody. Importantly, therapeutic outcomes of some immunological treatments are different between NMO and MS, making early differential diagnosis of these two disorders crucial. We provide an overview of the epidemiology, clinical and neuroimaging features, immunopathology and therapy of NMO and NMO spectrum disorders.

  15. Aquaporin-4 Deficient Mice have Increased Extracellular Space Without Tortuosity Change

    PubMed Central

    Yao, Xiaoming; Hrabětová, Sabina; Nicholson, Charles; Manley, Geoffrey T.

    2008-01-01

    Aquaporin-4 (AQP4) is the major water channel expressed at fluid-tissue barriers throughout the brain and plays a crucial role in cerebral water balance. To assess whether these channels influence brain extracellular space (ECS) under resting physiological conditions, we used the established real-time iontophoresis method with tetramethylammonium (TMA+) to measure three diffusion parameters: ECS volume fraction (α), tortuosity (λ), and TMA+ loss (k’). In vivo measurements were performed in the somatosensory cortex of AQP4 deficient (AQP4-/-) mice and wild-type controls with matched age. Mice lacking AQP4 showed a 28% increase in α (0.23 ± 0.007 vs. 0.18 ± 0.003) with no differences in λ (1.62 ± 0.04 vs. 1.61 ± 0.02) and k’ (0.0045 ± 0.0001 1/sec vs. 0.0031 ± 0.0009 1/sec). Additional recordings in brain slices showed similarly elevated α in AQP4-/- mice, and no differences in λ and k’ between the two genotypes. This is the first direct comparison of ECS properties in adult mice lacking AQP4 water channels with wild-type animals and demonstrates a significant enlargement of the volume fraction but no difference in hindrance to TMA+ diffusion, expressed as tortuosity. These findings provide direct evidence for involvement of AQP4 in modulation of the ECS volume fraction and provide a basis for future modeling of water and ion transport in the central nervous system. PMID:18495879

  16. Reversible, Temperature-Dependent Supramolecular Assembly of Aquaporin-4 Orthogonal Arrays in Live Cell Membranes

    PubMed Central

    Crane, Jonathan M.; Verkman, A.S.

    2009-01-01

    Abstract The shorter “M23” isoform of the glial cell water channel aquaporin-4 (AQP4) assembles into orthogonal arrays of particles (OAPs) in cell plasma membranes, whereas the full-length “M1” isoform does not. N-terminal residues are responsible for OAP formation by AQP4-M23 and for blocking of OAP formation in AQP4-M1. In investigating differences in OAP formation by certain N-terminus mutants of AQP4, as measured by freeze-fracture electron microscopy versus live-cell imaging, we discovered reversible, temperature-dependent OAP assembly of certain weakly associating AQP4 mutants. Single-particle tracking of quantum-dot-labeled AQP4 in live cells and total internal reflection fluorescence microscopy showed >80% of M23 in OAPs at 10–50°C compared to <10% of M1. However, OAP formation by N-terminus cysteine-substitution mutants of M1, which probe palmitoylation-regulated OAP assembly, was strongly temperature-dependent, increasing from <10% at 37°C to >70% at 10°C for the double mutant M1-C13A/C17A. OAP assembly by this mutant, but not by native M23, could also be modulated by reducing its membrane density. Exposure of native M1 and single cysteine mutants to 2-bromopalmitate confirmed the presence of regulated OAP assembly by S-palmitoylation. Kinetic studies showed rapid and reversible OAP formation during cooling and OAP disassembly during heating. Our results provide what to our knowledge is the first information on the energetics of AQP4 OAP assembly in plasma membranes. PMID:19948131

  17. Effects of propofol and sevoflurane on aquaporin-4 and aquaporin-9 expression in patients performed gliomas resection.

    PubMed

    Yang, Wan-Chao; Zhou, Li-Jie; Zhang, Rui; Yue, Zi-Yong; Dong, Hong; Song, Chun-Yu; Qian, Hua; Lu, Shu-Jun; Chang, Fei-Fei

    2015-10-05

    Post-operative cerebral edema is a threat for patients performed gliomas resection. Some studies have shown that general anesthesia drugs, such as, propofol had neuroprotective effect. Aquaporin-4 (AQP4) and Aquaporin-9 (AQP9) play an important role in maintaining brain water homeostasis under various conditions. The aim of this study was to compare the effect of propofol or sevoflurane on expression of AQP4 and AQP9 in patients performed gliomas resection. 30 patients performed gliomas resection were included in this study. The patients were randomly divided into two groups: propofol group and sevoflurane group. Fresh human gliomas specimens were obtained and hematoxylin eosin (HE) staining, immunohistochemical staining and Western blot analysis were used for observation of the expression of AQP4 and AQP9. The immunohistochemical staining of the sections showed that the percentage of AQP4 positive cells in the propofol group (14.3±4.61%) was significantly lower than that in sevoflurane group (37.3±10.01%) (n=15, P<0.05). There was no significant difference in the percentage of AQP9 positive cells in propofol group and sevoflurane group (25.8±2.67 versus 28.1±7.81%, n=15, P>0.05). Western blot analysis confirmed the immunohistochemistry results. AQP4 protein level in propofol group was significantly lower than that in sevoflurane group (1.4±0.13 versus 1.7±0.12, P<0.05). Western blot analysis did not show any difference of expression of AQP9 protein between the propofol group and sevoflurane group (2.0±0.13 versus 2.1±0.13, P>0.05, n=6). AQP4 expression was lower in patients of propofol group than that in sevoflurane group. Our results suggested that propofol could inhibit the expression of AQP4.

  18. Inhibitor(s) of the classical complement pathway in mouse serum limit the utility of mice as experimental models of neuromyelitis optica.

    PubMed

    Ratelade, Julien; Verkman, A S

    2014-11-01

    Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the central nervous system in which anti-aquaporin-4 (AQP4) autoantibodies (AQP4-IgG) cause damage to astrocytes by complement-dependent cytotoxicity (CDC). Various approaches have been attempted to produce NMO lesions in rodents, some involving genetically modified mice with altered immune cell function. Here, we found that mouse serum strongly inhibits complement from multiple species, preventing AQP4-IgG-dependent CDC. Effects of mouse serum on complement activation were tested in CDC assays in which AQP4-expressing cells were incubated with AQP4-IgG and complement from different species. Biochemical assays and mass spectrometry were used to characterize complement inhibitor(s) in mouse serum. Sera from different strains of mice produced almost no AQP4-IgG-dependent CDC compared with human, rat and guinea pig sera. Remarkably, addition of mouse serum prevented AQP4-IgG-dependent CDC caused by human, rat or guinea pig serum, with 50% inhibition at <5% mouse serum. Hemolysis assays indicated that the inhibitor(s) in mouse serum target the classical and not the alternative complement pathway. We found that the complement inhibitor(s) in mouse serum were contained in a serum fraction purified with protein-A resin; however, the inhibitor was not IgG as determined using serum from IgG-deficient mice. Mass spectrometry on the protein A-purified fraction produced several inhibitor candidates. The low intrinsic complement activity of mouse serum and the presence of complement inhibitor(s) limit the utility of mouse models to study disorders, such as NMO, involving the classical complement pathway.

  19. Aquaporin-4 Deletion in Mice Reduces Encephalopathy and Brain Edema in Experimental Acute Liver Failure

    PubMed Central

    Rama Rao, Kakulavarapu V.; Verkman, A. S.; Curtis, Kevin M.; Norenberg, Michael D.

    2014-01-01

    Brain edema and associated astrocyte swelling leading to increased intracranial pressure are hallmarks of acute liver failure (ALF). Elevated blood and brain levels of ammonia have been implicated in the development of brain edema in ALF. Cultured astrocytes treated with ammonia have been shown to undergo cell swelling and such swelling was associated with an increase in the plasma membrane expression of aquaporin-4 (AQP4) protein. Further, silencing the AQP4 gene in cultured astrocytes was shown to prevent the ammonia-induced cell swelling. Here, we examined the evolution of brain edema in AQP4-null mice and their wild type counterparts (WT-mice) in different models of ALF induced by thioacetamide (TAA) or acetaminophen (APAP). Induction of ALF with TAA or APAP significantly increased brain water content in WT mice (by 1.6 ± 0.3 and 2.3 ± 0.4 %, respectively). AQP4 protein was significantly increased in brain plasma membranes of WT mice with ALF induced by either TAA or APAP. In contrast to WT-mice, brain water content did not increase in AQP4-null mice. Additionally, AQP4-null mice treated with either TAA or APAP showed a remarkably lesser degree of neurological deficits as compared to WT mice; the latter displayed an inability to maintain proper gait, and demonstrated a markedly reduced exploratory behavior, with the mice remaining in one corner of the cage with its head tilted downwards. These results support a central role of AQP4 in the brain edema associated with ALF. PMID:24321433

  20. Hypoxia-inducible factor-1α contributes to brain edema after stroke by regulating aquaporins and glycerol distribution in brain.

    PubMed

    Higashida, Tetsuhiro; Peng, Changya; Li, Jie; Dornbos, David; Teng, Kailing; Li, Xiaohua; Kinni, Harish; Guthikonda, Murali; Ding, Yuchuan

    2011-02-01

    Brain edema following stroke is a critical clinical problem due to its association with increased morbidity and mortality. Despite its significance, present treatment for brain edema simply provides symptomatic relief due to the fact that molecular mechanisms underlying brain edema remain poorly understood. The present study investigated the role of hypoxia-inducible factor-1α (HIF-1α) and aquaporins (AQP-4 and -9) in regulating cerebral glycerol accumulation and inducing brain edema in a rodent model of stroke. Two-hours of middle cerebral artery occlusion (MCAO) followed by reperfusion was performed in male Sprague-Dawley rats (250-280 g). Anti-AQP-4 antibody, anti-AQP-9 antibody, or 2-Methoxyestradiol (2ME2, an inhibitor of HIF-1α) was given at the time of MCAO. The rats were sacrificed at 1 and 24 hours after reperfusion and their brains were examined. Extracellular and intracellular glycerol concentration of brain tissue was calculated with an enzymatic glycerol assay. The protein expressions of HIF-1α, AQP-4 and AQP-9 were determined by Western blotting. Brain edema was measured by brain water content. Compared to control, edema (p < 0.01), increased glycerol (p < 0.05), and enhanced expressions of HIF-1α, AQP-4, and AQP-9 (p < 0.05) were observed after stroke. With inhibition of AQP-4, AQP-9 or HIF-1α, edema and extracellular glycerol were significantly (p < 0.01) decreased while intracellular glycerol was increased (p < 0.01) 1 hour after stroke. Inhibition of HIF-1α with 2ME2 suppressed (p < 0.01) the expression of AQP-4 and AQP-9. These findings suggest that HIF-1α serves as an upstream regulator of cerebral glycerol concentrations and brain edema via a molecular pathway involving AQP-4 and AQP-9. Pharmacological blockade of this pathway in stroke patients may provide novel therapeutic strategies.

  1. An unusual twin-his arrangement in the pore of ammonia channels is essential for substrate conductance.

    PubMed

    Javelle, Arnaud; Lupo, Domenico; Zheng, Lei; Li, Xiao-Dan; Winkler, Fritz K; Merrick, Mike

    2006-12-22

    Amt proteins constitute a class of ubiquitous integral membrane proteins that mediate movement of ammonium across cell membranes. They are homotrimers, in which each subunit contains a narrow pore through which substrate transport occurs. Two conserved histidine residues in the pore have been proposed to be necessary for ammonia conductance. By analyzing 14 engineered polar and non-polar variants of these histidines, in Escherichia coli AmtB, we show that both histidines are absolutely required for optimum substrate conductance. Crystal structures of variants confirm that substitution of the histidine residues does not affect AmtB structure. In a subgroup of Amt proteins, found only in fungi, one of the histidines is replaced by glutamate. The equivalent substitution in E. coli AmtB is partially active, and the structure of this variant suggests that the glutamate side chain can make similar interactions to those made by histidine.

  2. Steady state growth of E. Coli in low ammonium environment

    NASA Astrophysics Data System (ADS)

    Kim, Minsu; Deris, Barret; Zhang, Zhongge; Hwa, Terry

    2011-03-01

    Ammonium is the preferred nitrogen source for many microorganisms. In medium with low ammonium concentrations, enteric bacteria turn on the nitrogen responsive (ntr) genes to assimilate ammonium. Two proteins in E. coli, Glutamine synthetase (GS) and the Ammonium/methylammonium transporter AmtB play crucial roles in this regard. GS is the major ammonium assimilation enzyme below 1mM of NH4 + . AmtB is an inner membrane protein that transports NH4 + across the cell membrane against a concentration gradient. In order to study ammonium uptake at low NH4 + concentration at neutral pH, we developed a microfluidic flow chamber that maintains a homogenous nutrient environment during the course of exponential cell growth, even at very low concentration of nutrients. Cell growth can be accurately monitored using time-lapse microscopy. We followed steady state growth down to micro-molar range of NH4 + for the wild type and Δ amtB strains. The wild type strain is able to maintain the growth rate from 10mM down to a few uM of NH4 + , while the mutant exhibited reduced growth below ~ 20 ~uM of NH4 + . Simultaneous characterization of the expression levels of GS and AmtB using fluorescence reporters reveals that AmtB is turned on already at 1mM, but contributes to function only below ~ 30 ~uM in the wild-type. Down to ~ 20 ~uM of NH4 + , E.~coli can compensate the loss of AmtB by GS alone.

  3. Hyperosmotic stress induces cisplatin sensitivity in ovarian cancer cells by stimulating aquaporin-5 expression

    PubMed Central

    CHEN, XUEJUN; ZHOU, CHUNXIA; YAN, CHUNXIAO; MA, JIONG; ZHENG, WEI

    2015-01-01

    Aquaporins (AQPs) are important mediators of water permeability and are closely associated with tumor cell proliferation, migration, angiogenesis and chemoresistance. Moreover, the chemosensitivity of tumor cells to cisplatin (CDDP) is potentially affected by osmotic pressure. The present study was undertaken to determine whether hyperosmosis regulates ovarian cancer cell sensitivity to CDDP in vitro and to explore whether this is associated with AQP expression. The hyperosmotic stress was induced by D-sorbitol. 3AO ovarian cancer cells were treated with different concentrations of hypertonic medium and/or CDDP for various times, followed by measuring the inhibition rate of cell proliferation using an MTT assay. In addition, AQP expression in response to osmotic pressure and/or CDDP was measured by reverse transcription-quantitative polymerase chain reaction and western blotting. Cell proliferation in response to hypertonic stress was also measured when AQP5 was knocked down by small interfering (si)RNA. 3AO cell proliferation was inhibited by hyperosmotic stress, while the expression of AQP5, but not that of AQP1, AQP3 or AQP9, was increased in a dose- and time-dependent manner in hypertonic sorbitol-containing medium. When AQP5 was silenced by siRNA, cells were susceptible to hypertonic stress. MTT analyses showed that the inhibition of cell proliferation by a low dose of CDDP increased significantly with exposure to a hyperosmotic stimulus, and this effect was reduced when a high dose of CDDP was used. AQP5 expression was induced by a low dose of CDDP, but was reduced by a high dose of CDDP. However, hyperosmosis enhanced AQP5 mRNA expression at every dose of CDDP tested, compared with isotonic medium. With prolonged treatment time, AQP5 expression was reduced by CDDP in hypertonic and isotonic culture medium. Thus, the effects of hyperosmosis on cell sensitivity to CDDP were associated with AQP5 expression. These results suggest that AQP5 expression in ovarian

  4. Efficacy of Polyvalent Human Immunoglobulins in an Animal Model of Neuromyelitis Optica Evoked by Intrathecal Anti-Aquaporin 4 Antibodies

    PubMed Central

    Grünewald, Benedikt; Bennett, Jeffrey L.; Toyka, Klaus V.; Sommer, Claudia; Geis, Christian

    2016-01-01

    Neuromyelitis Optica Spectrum Disorders (NMOSD) are associated with autoantibodies (ABs) targeting the astrocytic aquaporin-4 water channels (AQP4-ABs). These ABs have a direct pathogenic role by initiating a variety of immunological and inflammatory processes in the course of disease. In a recently-established animal model, chronic intrathecal passive-transfer of immunoglobulin G from NMOSD patients (NMO-IgG), or of recombinant human AQP4-ABs (rAB-AQP4), provided evidence for complementary and immune-cell independent effects of AQP4-ABs. Utilizing this animal model, we here tested the effects of systemically and intrathecally applied pooled human immunoglobulins (IVIg) using a preventive and a therapeutic paradigm. In NMO-IgG animals, prophylactic application of systemic IVIg led to a reduced median disease score of 2.4 on a 0–10 scale, in comparison to 4.1 with sham treatment. Therapeutic IVIg, applied systemically after the 10th intrathecal NMO-IgG injection, significantly reduced the disease score by 0.8. Intrathecal IVIg application induced a beneficial effect in animals with NMO-IgG (median score IVIg 1.6 vs. sham 3.7) or with rAB-AQP4 (median score IVIg 2.0 vs. sham 3.7). We here provide evidence that treatment with IVIg ameliorates disease symptoms in this passive-transfer model, in analogy to former studies investigating passive-transfer animal models of other antibody-mediated disorders. PMID:27571069

  5. Neuromyelitis optica: a positive appraisal of seronegative cases.

    PubMed

    Bernard-Valnet, R; Liblau, R S; Vukusic, S; Marignier, R

    2015-12-01

    Neuromyelitis optica (NMO) is a rare inflammatory disorder of the central nervous system. The hallmark of NMO is the presence of specific autoantibodies directed against aquaporin 4 (AQP4-IgG). AQP4-IgG, included in diagnostic criteria, has enlarged the clinical spectrum of NMO and serves to predict relapses. Moreover AQP4-IgG has provided unprecedented insight in the immunopathology of NMO, representing a rationale for therapeutic intervention with relevant novel treatment strategies specific for NMO. However, some patients remain seronegative for AQP4-IgG despite a definite diagnosis of NMO and the use of the finest methods for antibody detection. Interestingly, seronegative NMO (NMO(neg)) patients exhibit different demographic and disease-related characteristics in comparison to seropositive patients. The recent association with autoantibodies specific for myelin oligodendrocyte glycoprotein (MOG) is the main indication that disease mechanisms might differ in NMO(pos) and NMO(neg), challenging the position of NMO(neg) patients in the spectrum of demyelinating diseases and therapeutic strategies to be adopted. Thus, a reappraisal of the NMO(neg) population is needed to improve NMO care. Here the current knowledge regarding NMO(neg) is reviewed and hypotheses on its pathogenesis are made including a comprehensive description of detection methods and the prevalence of AQP4-IgG and a review of the epidemiological, clinical and paraclinical characteristics of NMO(neg); finally an integrated view of the general pathophysiological mechanisms underlying NMO(neg) is provided.

  6. Higher order structure of aquaporin-4.

    PubMed

    Nicchia, G P; Rossi, A; Mola, M G; Pisani, F; Stigliano, C; Basco, D; Mastrototaro, M; Svelto, M; Frigeri, A

    2010-07-28

    Unlike other mammalian AQPs, multiple tetramers of AQP4 associate in the plasma membrane to form peculiar structures called Orthogonal Arrays of Particles (OAPs), that are observable by freeze-fracture electron microscopy (FFEM). However, FFEM cannot give information about the composition of OAPs of different sizes, and due to its technical complexity is not easily applicable as a routine technique. Recently, we employed the 2D gel electrophoresis BN-SDS/PAGE that for the first time enabled the biochemical isolation of AQP4-OAPs from several tissues. We found that AQP4 protein is present in several higher-order complexes (membrane pools of supra-structures) which contain different ratios of M1/M23 isoforms corresponding to AQP4-OAPs of different size. In this paper, we illustrate in detail the potentiality of 2D BN/SDS-PAGE for analyzing AQP4 supra-structures, their relationship with the dystrophin glycoprotein complex and other membrane proteins, and their role as a specific target of Neuromyelitis Optica autoantibodies.

  7. Effects of neuromyelitis optica–IgG at the blood–brain barrier in vitro

    PubMed Central

    Takeshita, Yukio; Obermeier, Birgit; Cotleur, Anne C.; Spampinato, Simona F.; Shimizu, Fumitaka; Yamamoto, Erin; Sano, Yasuteru; Kryzer, Thomas J.; Lennon, Vanda A.; Kanda, Takashi

    2016-01-01

    Objective: To address the hypothesis that physiologic interactions between astrocytes and endothelial cells (EC) at the blood–brain barrier (BBB) are afflicted by pathogenic inflammatory signaling when astrocytes are exposed to aquaporin-4 (AQP4) antibodies present in the immunoglobulin G (IgG) fraction of serum from patients with neuromyelitis optica (NMO), referred to as NMO-IgG. Methods: We established static and flow-based in vitro BBB models incorporating co-cultures of conditionally immortalized human brain microvascular endothelial cells and human astrocyte cell lines with or without AQP4 expression. Results: In astrocyte–EC co-cultures, exposure of astrocytes to NMO-IgG decreased barrier function, induced CCL2 and CXCL8 expression by EC, and promoted leukocyte migration under flow, contingent on astrocyte expression of AQP4. NMO-IgG selectively induced interleukin (IL)-6 production by AQP4-positive astrocytes. When EC were exposed to IL-6, we observed decreased barrier function, increased CCL2 and CXCL8 expression, and enhanced leukocyte transmigration under flow. These effects were reversed after application of IL–6 neutralizing antibody. Conclusions: Our results indicate that NMO-IgG induces IL-6 production by AQP4-positive astrocytes and that IL-6 signaling to EC decreases barrier function, increases chemokine production, and enhances leukocyte transmigration under flow. PMID:28018943

  8. Effects of dexamethasone on aquaporin-4 expression in brain tissue of rat with bacterial meningitis

    PubMed Central

    Du, Kai-Xian; Dong, Yan; Zhang, Yan; Hou, Li-Wei; Fan, Dong-Xia; Luo, Yu; Zhang, Xiao-Li; Jia, Tian-Ming; Lou, Ji-Yu

    2015-01-01

    Aquaporin-4 (AQP4) is the most popular water channel protein expressed in brain tissue and plays a very important role in regulating the water balance in and outside of brain parenchyma. To investigate the expression of aquaporin-4 in the rat brain tissue after dexamethasone therapy of meningitis induced by Streptococcus pneumonia, total 40 of 3-week old Sprague-Dawley rats were divided into infection group (n=30) and normal control group (n=10). The meningitis groups were infected with 1×107 cfu/ml of Streptococcus pneumoniae and then randomized into no treatment (untreated group, n=10), treatment with ceftriaxone (CTRX group, n=10) and treatment with dexamethasone combined ceftriaxone (CTRX + DEXA group, n=10). The normal control group was established by using saline. The rats were euthanized when they reached terminal illness or five days after infection, followed by detection of AQP4 through using immunohistochemistry and Western blot methods. Data has showed that expression of AQP4 in model group remained higher than the control and treatment group (P<0.05). AQP4 expression in CTRX + DEXA group was lower than that in CTRX group (P<0.05). There was no statistical difference between CTRX + DEXA group and the control group (P>0.05). These data suggested that Dexamethasone could down-regulate the expression of AQP4 in the brain tissue of rats with meningitis and provides evidence for the mechanism of protective effect of Dexamethasone on central neurosystem. PMID:26045822

  9. Neuromyelitis optica and the evolving spectrum of autoimmune aquaporin-4 channelopathies: a decade later

    PubMed Central

    Pittock, Sean J.; Lucchinetti, Claudia F.

    2015-01-01

    The discovery of AQP4-IgG (a pathogenic antibody that targets the astrocytic water channel aquaporin-4) as the first sensitive and specific biomarker for any inflammatory central nervous system demyelinating disease, has shifted emphasis from the oligodendrocyte and myelin to the astrocyte as a central immunopathogenic player. Neuromyelitis optica (NMO) spectrum disorders (SD) represent an evolving spectrum of IDDs extending beyond the optic nerves and spinal cord to include the brain (especially in children) and, rarely, muscle. NMOSD typical brain lesions are located in areas that highly express the target antigen, AQP4, including the circumventricular organs (accounting for intractable nausea and vomiting) and the diencephalon (accounting for sleep disorders, endocrinopathies, and syndrome of inappropriate antidiuresis). Magnetic resonance imaging (MRI) brain abnormalities fulfill Barkoff criteria for multiple sclerosis in up to 10% of patients. As the spectrum broadens, the importance of highly specific assays that detect pathogenic AQP4-IgG targeting extracellular epitopes of AQP4 cannot be overemphasized. The rapid evolution of our understanding of the immunobiology of AQP4 autoimmunity necessitates continuing revision of NMOSD diagnostic criteria. Here, we describe scientific advances that have occurred since the discovery of NMO-IgG in 2004 and review novel targeted immunotherapies. We also suggest that NMOSDs should now be considered under the umbrella term autoimmune aquaporin-4 channelopathy. PMID:26096370

  10. Aquaporin-4 regulates extracellular space volume dynamics during high-frequency synaptic stimulation: a gene deletion study in mouse hippocampus.

    PubMed

    Haj-Yasein, Nadia Nabil; Jensen, Vidar; Østby, Ivar; Omholt, Stig W; Voipio, Juha; Kaila, Kai; Ottersen, Ole P; Hvalby, Øivind; Nagelhus, Erlend A

    2012-05-01

    Little is known about the physiological roles of aquaporin-4 (AQP4) in the central nervous system. AQP4 water channels are concentrated in endfeet membranes of astrocytes but also localize to the fine astrocytic processes that abut central synapses. Based on its pattern of expression, we predicted that AQP4 could be involved in controlling water fluxes and changes in extracellular space (ECS) volume that are associated with activation of excitatory pathways. Here, we show that deletion of Aqp4 accentuated the shrinkage of the ECS that occurred in the mouse hippocampal CA1 region during activation of Schaffer collateral/commissural fibers. This effect was found in the stratum radiatum (where perisynaptic astrocytic processes abound) but not in the pyramidal cell layer (where astrocytic processes constitute but a minor volume fraction). For both genotypes the ECS shrinkage was most pronounced in the pyramidal cell layer. Our data attribute a physiological role to AQP4 and indicate that this water channel regulates extracellular volume dynamics in the mammalian brain.

  11. Hydrocephalus: the role of cerebral aquaporin-4 channels and computational modeling considerations of cerebrospinal fluid.

    PubMed

    Desai, Bhargav; Hsu, Ying; Schneller, Benjamin; Hobbs, Jonathan G; Mehta, Ankit I; Linninger, Andreas

    2016-09-01

    Aquaporin-4 (AQP4) channels play an important role in brain water homeostasis. Water transport across plasma membranes has a critical role in brain water exchange of the normal and the diseased brain. AQP4 channels are implicated in the pathophysiology of hydrocephalus, a disease of water imbalance that leads to CSF accumulation in the ventricular system. Many molecular aspects of fluid exchange during hydrocephalus have yet to be firmly elucidated, but review of the literature suggests that modulation of AQP4 channel activity is a potentially attractive future pharmaceutical therapy. Drug therapy targeting AQP channels may enable control over water exchange to remove excess CSF through a molecular intervention instead of by mechanical shunting. This article is a review of a vast body of literature on the current understanding of AQP4 channels in relation to hydrocephalus, details regarding molecular aspects of AQP4 channels, possible drug development strategies, and limitations. Advances in medical imaging and computational modeling of CSF dynamics in the setting of hydrocephalus are summarized. Algorithmic developments in computational modeling continue to deepen the understanding of the hydrocephalus disease process and display promising potential benefit as a tool for physicians to evaluate patients with hydrocephalus.

  12. Ischemic Postconditioning Alleviates Brain Edema After Focal Cerebral Ischemia Reperfusion in Rats Through Down-Regulation of Aquaporin-4.

    PubMed

    Han, Dong; Sun, Miao; He, Ping-Ping; Wen, Lu-Lu; Zhang, Hong; Feng, Juan

    2015-07-01

    Cerebral edema is a serious complication associated with cerebral ischemia/reperfusion (I/R). Aquaporin-4 (AQP4) plays a role in generating postischemic edema after reperfusion. Recently, ischemic postconditioning (Postcond) has been shown to produce neuroprotective effects and reduce brain edema in rats after cerebral I/R. It is unclear if ischemic Postcond alleviates brain edema injury through regulation of AQP4. In this study, middle cerebral artery occlusion (MCAO) was induced in rats by filament insertion for 2 h following 24-h reperfusion: ischemic Postcond treatment was performed before reperfusion in the experimental group. We used the wet-dry weight ratio and transmission electron microscopy to evaluate brain edema after 24 h of reperfusion. We used immunohistochemistry and Western blot analyses to evaluate the distribution and expression of AQP4. Ischemic Postcond significantly reduced the water content of the brain tissue and swelling of the astrocytic foot processes. AQP4 expression increased in the I/R and Postcond groups compared to the sham group, but it decreased in the Postcond group compared to the I/R group. The results of our study suggest that ischemic Postcond effectively reduces brain edema after reperfusion by inhibiting AQP4 expression. The data in this study support the use of ischemic Postcond for alleviating brain edema after cerebral I/R.

  13. Expression of Aquaporin 1 and Aquaporin 4 in the Temporal Neocortex of Patients with Parkinson's Disease.

    PubMed

    Hoshi, Akihiko; Tsunoda, Ayako; Tada, Mari; Nishizawa, Masatoyo; Ugawa, Yoshikazu; Kakita, Akiyoshi

    2017-03-01

    The astrocytic water channel proteins aquaporin 1 (AQP1) and aquaporin 4 (AQP4) are known to be altered in brains affected by several neurodegenerative disorders, including Alzheimer's disease. However, AQP expression in brains affected by Parkinson's disease (PD) has not been described in detail. Recently, it has been reported that α-synuclein (α-syn)-immunolabeled astrocytes show preferential distribution in several cerebral regions, including the neocortex, in patients with PD. Here, we investigated whether AQP expression is associated with α-syn deposition in the temporal neocortex of PD patients. In accordance with the consensus criteria for dementia with Lewy bodies, the patients were classified into neocortical (PDneo), limbic (PDlim), and brain stem (PDbs) groups. Expressions of α-syn, AQP1, and AQP4 in the temporal lobes of the individual PD patients were examined immunohistochemically. Immunohistochemical analysis demonstrated more numerous AQP4-positive and AQP1-positive astrocytes in the PDneo group than in the PDbs, PDlim, and control groups. However, in the PDneo cases, these astrocytes were not often observed in α-syn-rich areas, and semiquantitative analysis revealed that there was a significant negative correlation between the levels of AQP4 and α-syn in layers V-VI, and between those of AQP1 and α-syn in layers II-III. These findings suggest that a defined population of AQP4- and AQP1-expressing reactive astrocytes may modify α-syn deposition in the neocortex of patients with PD.

  14. Involvement of water channel Aquaporin 5 in H2S-induced pulmonary edema.

    PubMed

    Xu, Chunyang; Jiang, Lei; Zou, Yuxia; Xing, Jingjing; Sun, Hao; Zhu, Baoli; Zhang, Hengdong; Wang, Jun; Zhang, Jinsong

    2017-01-01

    Acute exposure to hydrogen sulfide (H2S) poses a significant threat to life, and the lung is one of the primary target organs of H2S. However, the mechanisms involved in H2S-induced acute pulmonary edema are poorly understood. This study aims to investigate the effects of H2S on the expression of water channel aquaporin 5 (AQP5) and to elucidate the signaling pathways involved in AQP5 regulation. In an in vivo study, C57BL6 mice were exposed to sub-lethal concentrations of inhaled H2S, and histological injury of the lungs and ultrastructure injury of the epithelial cells were evaluated. With real-time PCR and western blot assays, we found that H2S exposure contributed to a significant decrease in AQP5 expression both in murine lung tissue and the A549 cell line, and the ERK1/2 and p38 MAPK signaling pathways were demonstrated to be implicated in AQP5 regulation. Therefore, adjusting AQP5 protein levels could be considered a therapeutic strategy for the treatment of APE induced by H2S and other hazardous gases.

  15. Urinary Excretion of Kidney Aquaporins as Possible Diagnostic Biomarker of Diabetic Nephropathy

    PubMed Central

    Rossi, Luigi; Nicoletti, Maria Celeste; Mastrofrancesco, Lisa; Di Franco, Antonella; Indrio, Francesca; Lella, Rossella; Laviola, Luigi; Giorgino, Francesco; Svelto, Maria; Gesualdo, Loreto

    2017-01-01

    Diabetic nephropathy (DN) is a microangiopathic complication of diabetes mellitus (DM) affecting one-third of diabetic patients. The large variability in the clinical presentation of renal involvement in patients with DM makes kidney biopsy a prerequisite for a correct diagnosis. However, renal biopsy is an invasive procedure associated with risk of major complications. Numerous studies aimed to identify a noninvasive biomarker of DN but, so far, none of these is considered to be sufficiently specific and sensitive. Water channel aquaporins (AQPs), expressed at the plasma membrane of epithelial tubular cells, are often dysregulated during DN. In this work, we analyzed the urine excretion of AQP5 and AQP2 (uAQP5 and uAQP2), via exosomes, in 35 diabetic patients: 12 normoalbuminuric with normal renal function (DM), 11 with proteinuric nondiabetic nephropathy (NDN), and 12 with histological diagnosis and classification of DN. ELISA and WB analysis independently showed that uAQP5 was significantly increased in DN patients. Interestingly, linear regression analysis showed a positive correlation between uAQP5 and the histological class of DN. The same analysis, focusing on uAQP2, showed comparable results. Taken together, these data suggest a possible use of AQP5 and AQP2 as novel noninvasive biomarkers to help in classifying the clinical stage of DN. PMID:28246612

  16. Differential expression of aquaporin 5 and aquaporin 3 in squamous cell carcinoma and adenoid cystic carcinoma.

    PubMed

    Ishimoto, Shunsuke; Wada, Koichiro; Usami, Yu; Tanaka, Noriaki; Aikawa, Tomonao; Okura, Masaya; Nakajima, Atsushi; Kogo, Mikihiko; Kamisaki, Yoshinori

    2012-07-01

    Aquaporins (AQPs) are a membrane protein family involved in the selective transport of water across cell membranes. Recent studies have reported the expression of AQP5 in several tumor types such as gastric, pulmonary, ovarian, pancreatic and colorectal cancer. We have previously reported the expression on tumor cells and the important role of AQP3 on cell growth in tongue cancer. However, little is known about the expression and precise role of AQP5 on squamous cell carcinoma (SCC) of the tongue. We investigated the expression of AQP5 and AQP3 in human oral SCC and adenoid cystic carcinoma (ACC). Overexpression of both AQP5 and AQP3 were immunohistochemically observed on tumor cells in SCC, whereas ACC cells were faintly stained with those antibodies against AQPs. Treatment with pan-AQP inhibitor or specific AQP5-siRNA showed inhibition of cell growth in SCC cell lines via the inhibition of integrins and the mitogen-activated protein kinase pathway. AQPs play important roles in cell growth in SCC rather than ACC.

  17. Update on biomarkers in neuromyelitis optica

    PubMed Central

    Melamed, Esther; Levy, Michael; Waters, Patrick J.; Sato, Douglas Kazutoshi; Bennett, Jeffrey L.; John, Gareth R.; Hooper, Douglas C.; Saiz, Albert; Bar-Or, Amit; Kim, Ho Jin; Pandit, Lakha; Leite, Maria Isabel; Asgari, Nasrin; Kissani, Najib; Hintzen, Rogier; Marignier, Romain; Jarius, Sven; Marcelletti, John; Smith, Terry J.; Yeaman, Michael R.

    2015-01-01

    Neuromyelitis optica (NMO) (and NMO spectrum disorder) is an autoimmune inflammatory disease of the CNS primarily affecting spinal cord and optic nerves. Reliable and sensitive biomarkers for onset, relapse, and progression in NMO are urgently needed because of the heterogeneous clinical presentation, severity of neurologic disability following relapses, and variability of therapeutic response. Detecting aquaporin-4 (AQP4) antibodies (AQP4-IgG or NMO-IgG) in serum supports the diagnosis of seropositive NMO. However, whether AQP4-IgG levels correlate with disease activity, severity, response to therapy, or long-term outcomes is unclear. Moreover, biomarkers for patients with seronegative NMO have yet to be defined and validated. Collaborative international studies hold great promise for establishing and validating biomarkers that are useful in therapeutic trials and clinical management. In this review, we discuss known and potential biomarkers for NMO. PMID:26236760

  18. Update on biomarkers in neuromyelitis optica.

    PubMed

    Melamed, Esther; Levy, Michael; Waters, Patrick J; Sato, Douglas Kazutoshi; Bennett, Jeffrey L; John, Gareth R; Hooper, Douglas C; Saiz, Albert; Bar-Or, Amit; Kim, Ho Jin; Pandit, Lakha; Leite, Maria Isabel; Asgari, Nasrin; Kissani, Najib; Hintzen, Rogier; Marignier, Romain; Jarius, Sven; Marcelletti, John; Smith, Terry J; Yeaman, Michael R; Han, May H; Aktas, Orhan; Apiwattanakul, Metha; Banwell, Brenda; Bichuetti, Denis; Broadley, Simon; Cabre, Philippe; Chitnis, Tanuja; De Seze, Jerome; Fujihara, Kazuo; Greenberg, Benjamin; Hellwig, Kerstin; Iorio, Raffaele; Jarius, Sven; Klawiter, Eric; Kleiter, Ingo; Lana-Peixoto, Marco; Nakashima; O'Connor, Kevin; Palace, Jacqueline; Paul, Friedman; Prayoonwiwat, Naraporn; Ruprecht, Klemens; Stuve, Olaf; Tedder, Thomas; Tenembaum, Silvia; Garrahan, Juan P; Aires, Buenos; van Herle, Katja; van Pelt, Danielle; Villoslada, Pablo; Waubant, Emmanuelle; Weinshenker, Brian; Wingerchuk, Dean; Würfel, Jens; Zamvil, Scott

    2015-08-01

    Neuromyelitis optica (NMO) (and NMO spectrum disorder) is an autoimmune inflammatory disease of the CNS primarily affecting spinal cord and optic nerves. Reliable and sensitive biomarkers for onset, relapse, and progression in NMO are urgently needed because of the heterogeneous clinical presentation, severity of neurologic disability following relapses, and variability of therapeutic response. Detecting aquaporin-4 (AQP4) antibodies (AQP4-IgG or NMO-IgG) in serum supports the diagnosis of seropositive NMO. However, whether AQP4-IgG levels correlate with disease activity, severity, response to therapy, or long-term outcomes is unclear. Moreover, biomarkers for patients with seronegative NMO have yet to be defined and validated. Collaborative international studies hold great promise for establishing and validating biomarkers that are useful in therapeutic trials and clinical management. In this review, we discuss known and potential biomarkers for NMO.

  19. Elderly-onset neuromyelitis optica which developed after the diagnosis of prostate adenocarcinoma and relapsed after a 23-valent pneumococcal polysaccharide vaccination.

    PubMed

    Kitazawa, Yu; Warabi, Yoko; Bandoh, Mitsuaki; Takahashi, Toshiyuki; Matsubara, Shiro

    2012-01-01

    We report a case of elderly-onset neuromyelitis optica (NMO) positive for the anti-aquaporin-4 (AQP-4) antibody; symptoms developed after the diagnosis of prostate adenocarcinoma and relapsed after a 23-valent pneumococcal polysaccharide vaccination. We suggest that activation of CD4-positive T cells and secretion of interferon-gamma induced by adenocarcinoma and complement activation induced by vaccination are responsible for the onset and relapse of NMO, even if a patient is positive for the anti-AQP-4 antibody. This case supports the previous experimental finding that the anti-AQP-4 antibody does not cause NMO-like lesions when injected alone, but does so after the induction of T cell-mediated experimental autoimmune encephalomyelitis or when co-injected with human complement.

  20. Features of anti-aquaporin 4 antibody-seropositive Chinese patients with neuromyelitis optica spectrum optic neuritis.

    PubMed

    Li, Hongyang; Wang, Yanling; Xu, Quangang; Zhang, Aidi; Zhou, Huanfen; Zhao, Shuo; Kang, Hao; Peng, Chunxia; Cao, Shanshan; Wei, Shihui

    2015-10-01

    The detection of anti-aquaporin-4 autoantibody (AQP-4 Ab) is crucial to detect patients who will develop neuromyelitis optica (NMO); however, there are few studies on the AQP-4 Ab serostatus of patients with neuromyelitis optica spectrum ON. We analyzed the clinical and paraclinical features of neuromyelitis optica spectrum ON patients in China according to the patients' AQP4-Ab serostatus. 125 patients with recurrent and bilateral ON with simultaneous attacks were divided into AQP-4 Ab-seropositive and -seronegative groups. Demographic, clinical, serum autoantibody data, connective tissue disorders (CTDs), visual performance were compared. A Visual Acuity (VA) of less than 0.1 during acute ON attacks occurred more frequently in the seropositive group (p = 0.023); however, there was not a significant difference between groups on VA recovery after the first attack. The seropositive group experienced the worst outcome during the last attack (p = 0.017). Other co-existing autoimmunity antibodies (p < 0.001) and CTDs (p < 0.001) were more prevalent in seropositive patients. There were no significant differences on VA recovery and RNFLT combined with other autoantibodies or CTDs. The two groups did not differ significantly with regard to time to relapse, annualized relapse rates, time of diagnosis NMO, or RNFL. There were no significant differences on VA recovery and RNFLT combined with other autoantibodies or CTDs. RNFLT was thinner in NMO seropositive patients. Although AQP-4 Ab expression predicted poor visual outcome, positive patients were usually associated with mild symptoms at first onset. Anti-SSA/SSB antibody or Sjögren syndrome may be associated with AQP-4 Ab in neuromyelitis optica spectrum ON.

  1. Development of an Aquaporin-4 Orthogonal Array of Particle-Based ELISA for Neuromyelitis Optica Autoantibodies Detection

    PubMed Central

    Pisani, Francesco; Settanni, Paolo; Rosito, Stefania; Mola, Maria Grazia; Iorio, Raffaele; Tortorella, Carla; Ruggieri, Maddalena; Trojano, Maria; Svelto, Maria; Frigeri, Antonio; Nicchia, Grazia Paola

    2015-01-01

    Serological markers of Nuromyelitis Optica (NMO), an autoimmune disorder of the central nervous system, are autoantibodies targeting the astrocytic water channel aquaporin-4 (AQP4). We have previously demonstrated that the main epitopes for these autoantibodies (AQP4-IgG) are generated by the supramolecular arrangement of AQP4 tetramers into an Orthogonal Array of Particles (OAPs). Many tests have been developed to detect AQP4-IgG in patient sera but several procedural issues affect OAP assembly and consequently test sensitivity. To date, the protein based ELISA test shows the lowest sensitivity while representing a valid alternative to the more sensitive cell based assay (CBA), which, however, shows economic, technical and interpretation problems. Here we have developed a high perfomance ELISA in which native OAPs are used as the molecular target. To this aim a native size exclusion chromatography method has been developed to isolate integral, highly pure and AQP4-IgG-recognized OAPs from rat brain. These OAPs were immobilized and oriented on a plastic plate by a sandwich approach and 139 human sera were tested, including 67 sera from NMO patients. The OAP-ELISA showed a 99% specificity and a higher sensitivity (91%) compared to the CBA test. A comparative analysis revealed an end-point titer three orders of magnitude higher than the commercial ELISA and six times higher than our in-house CBA test. We show that CNS-extracted OAPs are crucial elements in order to perform an efficient AQP4-IgG test and the OAP-ELISA developed represents a valid alternative to the CBA currently used. PMID:26599905

  2. Development of an Aquaporin-4 Orthogonal Array of Particle-Based ELISA for Neuromyelitis Optica Autoantibodies Detection.

    PubMed

    Pisani, Francesco; Settanni, Paolo; Rosito, Stefania; Mola, Maria Grazia; Iorio, Raffaele; Tortorella, Carla; Ruggieri, Maddalena; Trojano, Maria; Svelto, Maria; Frigeri, Antonio; Nicchia, Grazia Paola

    2015-01-01

    Serological markers of Nuromyelitis Optica (NMO), an autoimmune disorder of the central nervous system, are autoantibodies targeting the astrocytic water channel aquaporin-4 (AQP4). We have previously demonstrated that the main epitopes for these autoantibodies (AQP4-IgG) are generated by the supramolecular arrangement of AQP4 tetramers into an Orthogonal Array of Particles (OAPs). Many tests have been developed to detect AQP4-IgG in patient sera but several procedural issues affect OAP assembly and consequently test sensitivity. To date, the protein based ELISA test shows the lowest sensitivity while representing a valid alternative to the more sensitive cell based assay (CBA), which, however, shows economic, technical and interpretation problems. Here we have developed a high perfomance ELISA in which native OAPs are used as the molecular target. To this aim a native size exclusion chromatography method has been developed to isolate integral, highly pure and AQP4-IgG-recognized OAPs from rat brain. These OAPs were immobilized and oriented on a plastic plate by a sandwich approach and 139 human sera were tested, including 67 sera from NMO patients. The OAP-ELISA showed a 99% specificity and a higher sensitivity (91%) compared to the CBA test. A comparative analysis revealed an end-point titer three orders of magnitude higher than the commercial ELISA and six times higher than our in-house CBA test. We show that CNS-extracted OAPs are crucial elements in order to perform an efficient AQP4-IgG test and the OAP-ELISA developed represents a valid alternative to the CBA currently used.

  3. Loss or Mislocalization of Aquaporin-4 Affects Diffusion Properties and Intermediary Metabolism in Gray Matter of Mice.

    PubMed

    Pavlin, T; Nagelhus, E A; Brekken, C; Eyjolfsson, E M; Thoren, A; Haraldseth, O; Sonnewald, U; Ottersen, O P; Håberg, A K

    2017-01-01

    The first aim of this study was to determine how complete or perivascular loss of aquaporin-4 (AQP4) water channels affects membrane permeability for water in the mouse brain grey matter in the steady state. Time-dependent diffusion magnetic resonance imaging was performed on global Aqp4 knock out (KO) and α-syntrophin (α-syn) KO mice, in the latter perivascular AQP4 are mislocalized, but still functioning. Control animals were corresponding wild type (WT) mice. By combining in vivo diffusion measurements with the effective medium theory and previously measured extra-cellular volume fractions, the effects of membrane permeability and extracellular volume fraction were uncoupled for Aqp4 and α-syn KO. The second aim was to assess the effect of α-syn KO on cortical intermediary metabolism combining in vivo [1-(13)C]glucose and [1,2-(13)C]acetate injection with ex vivo (13)C MR spectroscopy. Aqp4 KO increased the effective diffusion coefficient at long diffusion times by 5%, and a 14% decrease in membrane water permeability was estimated for Aqp4 KO compared with WT mice. α-syn KO did not affect the measured diffusion parameters. In the metabolic analyses, significantly lower amounts of [4-(13)C]glutamate and [4-(13)C]glutamine, and percent enrichment in [4-(13)C]glutamate were detected in the α-syn KO mice. [1,2-(13)C]acetate metabolism was unaffected in α-syn KO, but the contribution of astrocyte derived metabolites to GABA synthesis was significantly increased. Taken together, α-syn KO mice appeared to have decreased neuronal glucose metabolism, partly compensated for by utilization of astrocyte derived metabolites.

  4. Effect of estrogen and/or progesterone administration on traumatic brain injury-caused brain edema: the changes of aquaporin-4 and interleukin-6.

    PubMed

    Soltani, Zahra; Khaksari, Mohammad; Shahrokhi, Nader; Mohammadi, Gholamabbas; Mofid, Behshad; Vaziri, Ali; Amiresmaili, Sedigheh

    2016-03-01

    The role of aquaporin-4 (AQP4) and interleukin-6 (IL-6) in the development of brain edema post-traumatic brain injury (TBI) has been indicated. The present study was designed to investigate the effect(s) of administration of progesterone (P) and/or estrogen (E) on brain water content, AQP4 expression, and IL-6 levels post-TBI. The ovariectomized rats were divided into 11 groups: sham, one vehicle, two vehicles, E1, E2, P1, P2, E1 + P1, E1 + P2, E2 + P1, and E2 + P2. The brain AQP4 expression, IL-6 levels, and water content were evaluated 24 h after TBI induced by Marmarou's method. The low (E1 and P1) and high (E2 and P2) doses of estrogen and progesterone were administered 30 min post-TBI. The results showed that brain water content and AQP4 expression decreased in the E1, E2, P1, and P2-treated groups. The administration of E1 decreased IL-6 levels. Addition of progesterone decreased the inhibitory effect of E1 and E2 on the accumulation of water in the brain. Administration of E1 + P1 and E1 + P2 decreased the inhibitory effect of E1 on the IL-6 levels and AQP4 protein expression. Our findings suggest that estrogen or progesterone by itself has more effective roles in decrease of brain edema than combination of both. Possible mechanism may be mediated by the alteration of AQP4 and IL-6 expression. However, further studies are required to verify the exact mechanism.

  5. Secondary Data Analytics of Aquaporin Expression Levels in Glioblastoma Stem-Like Cells

    PubMed Central

    Isokpehi, Raphael D; Wollenberg Valero, Katharina C; Graham, Barbara E; Pacurari, Maricica; Sims, Jennifer N; Udensi, Udensi K; Ndebele, Kenneth

    2015-01-01

    Glioblastoma is the most common brain tumor in adults in which recurrence has been attributed to the presence of cancer stem cells in a hypoxic microenvironment. On the basis of tumor formation in vivo and growth type in vitro, two published microarray gene expression profiling studies grouped nine glioblastoma stem-like (GS) cell lines into one of two groups: full (GSf) or restricted (GSr) stem-like phenotypes. Aquaporin-1 (AQP1) and aquaporin-4 (AQP4) are water transport proteins that are highly expressed in primary glial-derived tumors. However, the expression levels of AQP1 and AQP4 have not been previously described in a panel of 92 glioma samples. Therefore, we designed secondary data analytics methods to determine the expression levels of AQP1 and AQP4 in GS cell lines and glioblastoma neurospheres. Our investigation also included a total of 2,566 expression levels from 28 Affymetrix microarray probe sets encoding 13 human aquaporins (AQP0–AQP12); CXCR4 (the receptor for stromal cell derived factor-1 [SDF-1], a potential glioma stem cell therapeutic target]); and PROM1 (gene encoding CD133, the widely used glioma stem cell marker). Interactive visual representation designs for integrating phenotypic features and expression levels revealed that inverse expression levels of AQP1 and AQP4 correlate with distinct phenotypes in a set of cell lines grouped into full and restricted stem-like phenotypes. Discriminant function analysis further revealed that AQP1 and AQP4 expression are better predictors for tumor formation and growth types in glioblastoma stem-like cells than are CXCR4 and PROM1. Future investigations are needed to characterize the molecular mechanisms for inverse expression levels of AQP1 and AQP4 in the glioblastoma stem-like neurospheres. PMID:26279619

  6. Molecular machinery for vasotocin-dependent transepithelial water movement in amphibians: aquaporins and evolution.

    PubMed

    Suzuki, Masakazu; Shibata, Yuki; Ogushi, Yuji; Okada, Reiko

    2015-08-01

    Amphibians represent the first vertebrates to adapt to terrestrial environments, and are successfully distributed around the world. The ventral skin, kidney, and urinary bladder are important osmoregulatory organs for adult anuran amphibians. Water channel proteins, called aquaporins (AQPs), play key roles in transepithelial water absorption/reabsorption in these organs. At least 43 types of AQPs were identified in anurans; a recent phylogenetic analysis categorized anuran AQPs among 16 classes (AQP0-14, 16). Anuran-specific AQPa2 was assigned to AQP6, then was further subdivided into the ventral skin-type (AQP6vs; AQPa2S), whose expression is confined to the ventral skin, and the urinary bladder-type (AQP6ub; AQPa2U), which is basically expressed in the urinary bladder. For the osmoregulatory organs, AQP3 is constitutively located in the basolateral plasma membrane of tight-junctioned epithelial cells. AQP6vs, AQP2 and/or AQP6ub are also expressed in these epithelial cells and are translocated to the apical membrane in response to arginine vasotocin, thereby regulating water absorption/reabsorption. It was suggested recently that two subtypes of AQP6vs contribute to cutaneous water absorption in Ranid species. In addition, AQP5 (AQP5a) and AQP5L (AQP5b) were identified from Xenopus tropicalis Gray, 1864, and AQP5 was localized to the apical membrane of luminal epithelial cells of the urinary bladder in dehydrated Xenopus. This finding suggested that AQP5 may be involved in water reabsorption from this organ under dehydration. Based on the hitherto reported information, we propose models for the evolution of water-absorbing/reabsorbing mechanisms in anuran osmoregulatory organs in association with AQPs.

  7. A case of pathology-proven neuromyelitis optica spectrum disorder with Sjögren syndrome manifesting aphasia and apraxia due to a localized cerebral white matter lesion.

    PubMed

    Sawada, Jun; Orimoto, Ryosuke; Misu, Tatsuro; Katayama, Takayuki; Aizawa, Hitoshi; Asanome, Asuka; Takahashi, Kae; Saito, Tsukasa; Anei, Ryogo; Kamada, Kyousuke; Miyokawa, Naoyuki; Takahashi, Toshiyuki; Fujihara, Kazuo; Hasebe, Naoyuki

    2014-09-01

    A woman with Sjögren syndrome manifesting as aphasia with a left deep cerebral white matter lesion tested positive for anti-aquaporin 4 (AQP4) antibody. Open biopsy of the lesion revealed active demyelination with edematous changes and the preservation of most axons, indicating a non-necrotic demyelinating lesion. Immunostaining for AQP4 was diffusely lost, whereas the loss of glial fibrillary acidic protein immunostaining was limited but with highly degenerated astrocytic foot processes in perivascular areas. These results suggested neuromyelitis optica spectrum disorder (NMOSD) pathology rather than Sjögren-related vasculitis. Only cerebral cortical symptoms with a cerebral white matter lesion could be observed in NMOSDs.

  8. Development of a Small Molecule P2X7R Antagonist as a Treatment for Acute SCI

    DTIC Science & Technology

    2012-10-01

    brain edema. Methods Mice. Aqp4−/− mice were generated by GenOway by cloning and sequencing of a targeted region of the murine Aqp4 gene in a 129/Sv... genetic back- ground. The strategy was to design a targeted locus allowing us to delete exons 1–3 to avoid any expression of putative splice variants...was made on the back region and a laminectomy was performed aseptically at the T11-T12 level. Before SCI, a catheter was placed in the left femoral

  9. [Diagnostic criteria for neuromyelitisoptica spectrum disorders].

    PubMed

    Belova, A N; Boiko, A N; Belova, E M

    2016-01-01

    The review is devoted to revised international diagnostic criteria for neuromyelitisoptica spectrum disorders (NMOSD).Current diagnostic criteria allow NMOSD diagnosis not only for serum aquaporin-4 immunoglobulin G antibodies (AQP4-IgG)-seropositive patients but for AQP4-IgG-seronegative patients as well. New criteria are expected to make NMOSD diagnosis earlier and more accurate as well as to facilitate the differentiation with multiple sclerosis. Furthermore, unify international criteria should help to perform comparable epidemiologic studies and clinical trials of new drugs for NMOSD.

  10. Molecular Dynamic Study to Determine the Ammonia Conduction Mechanisms in Human RhCG and Bacterial Homoloques

    NASA Astrophysics Data System (ADS)

    Akgun, Ugur

    2014-03-01

    The transport of Ammonia is provided by Amt/MEP/Rh protein superfamily. The x-ray structures of AmtB from Escherichia coli, Rh50 from Nitrosomonas europaea, and human RhCG show only few differences on periplasmic vestibules. After more than microsecond simulation on three models, we determined the striking difference on conduction mechanism between bacterial AmtB and Human RhCG proteins. In AmtB the backbone carbonyl groups at the periplasmic vestibule direct charged ammonia to the conserved aromatic cage at the bottom of the vestibule. Furthermore, two partially stacked phenyl rings of F107 and F215, separating the periplasmic vestibule from the hydrophobic lumen, flip open and closed simultaneouslywith a frequency of approximately 108 flipping events per second. During the passage from the phenyl gates charged ammonia releases its proton and becomes gas. However, the absence of an aromatic cage on Rh proteins and a strongly conserved E166 residue in the vicinity hints different conduction mechanism. Our studies confirm the conserved E166 emerges as a strong charged ammonia recruitment site for Human RhCG. The conserved phenyl gate behaves different for Rh proteins and the synchronized motion is not observed. These findings suggest a different deprotonation mechanism than bacterial AmtB.

  11. "Why Are College Foreign Language Students' Self-Efficacy, Attitude, and Motivation so Different?"

    ERIC Educational Resources Information Center

    Hsieh, Pei-Hsuan

    2008-01-01

    Simply taking foreign language courses and being exposed to the language does not guarantee successful and positive learning experiences. When examining factors that influence foreign language learning, motivation should be considered. To extend current foreign language literature, this study integrated self-efficacy and Gardners' AMTB variables…

  12. Molecular determinants for binding of ammonium ion in the ammonia transporter AmtB-A quantum chemical analysis.

    PubMed

    Liu, Yuemin; Hu, Xiche

    2006-02-02

    The transport of ammonium across the cell membrane represents an important biological process in all living organisms. The mechanisms for ammonium translocation were analyzed by computer simulations based on first principles. Intermolecular interaction energies between the differentially methylated ammonium and the ammonium channel protein AmtB were calculated by means of the supermolecular approach at the MP2/6-311+G* level based on the high-resolution crystal structures of ligand-bound protein complexes. Our analysis attributes the molecular determinants for protein-ligand recognition in ammonium transporter AmtB to the aromatic cage formed by three aromatic residues Phe103, Phe107, and Trp148, as well as Ser219. The former residues are involved in cation-pi interactions with the positively charged methylated ammoniums. The latter residue acts as a hydrogen bond acceptor to ammonium. Thus, this work provides directly the missing evidence for the hypothesized role played by the wider vestibule site of AmtB at the periplasmic side of the membrane in "recruiting" NH(4)(+) or methylammonium ions as proposed by Khademi et al. (Science 2004, 305, 1587). In addition, a hybrid quantum mechanics/molecular mechanics scheme was applied to optimize the structures of differentially methylated ammoniums in the AmtB protein, which generated structural and energetic data that provide a satisfactory explanation to the experimental observation that tetramethylammonium is not inhibitory to conducting ammonium and methylammonium in the ammonium transport channel.

  13. Antibodies to Aquaporin 4, Myelin-Oligodendrocyte Glycoprotein, and the Glycine Receptor α1 Subunit in Patients With Isolated Optic Neuritis

    PubMed Central

    Martinez-Hernandez, Eugenia; Sepulveda, Maria; Rostásy, Kevin; Höftberger, Romana; Graus, Francesc; Harvey, Robert J.; Saiz, Albert; Dalmau, Josep

    2016-01-01

    IMPORTANCE In patients with isolated optic neuritis (ON), the presence of antibodies to aquaporin 4 (AQP4) has diagnostic and prognostic value. In the same clinical setting, the significance of antibodies to myelin-oligodendrocyte glycoprotein (MOG) or the glycine receptor α1 subunit (GlyR) is unclear. OBJECTIVES To investigate the frequency of antibodies to AQP4, MOG, and GlyR in patients with unilateral or bilateral, severe, or recurrent isolated ON and to determine their clinical and prognostic correlates. DESIGN, SETTING, AND PARTICIPANTS Retrospective case-control study from November 1, 2005, through May 30, 2014 with the detection of autoantibodies in a neuroimmunology referral center. We included 51 patients with ON but without clinical and magnetic resonance imaging findings outside the optic nerves and 142 controls (30 healthy individuals, 48 patients with neuromyelitis optica, and 64 patients with multiple sclerosis). MAIN OUTCOMES AND MEASURES Clinicoimmunologic analysis. We determined the presence of antibodies to AQP4, MOG, and GlyR using cell-based assays. RESULTS The median age of the patients at the onset of ON symptoms was 28 (range, 5–65) years; 36 patients (71%) were female. Antibodies were identified in 23 patients (45%), including MOG in 10 patients, AQP4 in 6 patients, and GlyR in 7 patients (concurrent with MOG in 3 and concurrent with AQP4 in 1). Patients with AQP4 antibodies (median visual score, 3.5 [range, 1–9]) had a worse visual outcome than patients with MOG antibodies alone (median visual score, 0 [range, 0–5]; P = .007), patients with seronegative findings (n = 28) (median visual score, 1.0 [range, 0–14]; P = .08), and patients with GlyR antibodies alone (n = 3) (median visual score, 0 [range, 0–2]; P = .10). The median age of the 7 patients with GlyR antibodies was 27 (range, 11–38) years; 5 (71%) of these were female. Among the 3 patients with GlyR antibodies alone, 1 patient had monophasic ON, 1 had recurrent isolated

  14. Comparative Analysis for the Presence of IgG Anti-Aquaporin-1 in Patients with NMO-Spectrum Disorders

    PubMed Central

    Sánchez Gomar, Ismael; Díaz Sánchez, María; Uclés Sánchez, Antonio José; Casado Chocán, José Luis; Suárez-Luna, Nela; Ramírez-Lorca, Reposo; Villadiego, Javier; Toledo-Aral, Juan José; Echevarría, Miriam

    2016-01-01

    Detection of IgG anti-Aquaporin-4 (AQP4) in serum of patients with Neuromyelitis optica syndrome disorders (NMOSD) has improved diagnosis of these processes and differentiation from Multiple sclerosis (MS). Recent findings also claim that a subgroup of patients with NMOSD, serum negative for IgG-anti-AQP4, present antibodies anti-AQP1 instead. Explore the presence of IgG-anti-AQP1 using a previously developed cell-based assay (CBA) highly sensitive to IgG-anti-AQP4. Serum of 205 patients diagnosed as NMOSD (8), multiple sclerosis (94), optic neuritis (39), idiopathic myelitis (29), other idiopathic demyelinating disorders of the central nervous system (9), other neurological diseases (18) and healthy controls (8), were used in a CBA over fixed HEK cells transfected with hAQP1-EGFP or hM23-AQP4-EGFP, treated with Triton X-100 and untreated. ELISA was also performed. Analysis of serum with our CBA indicated absence of anti-AQP1 antibodies, whereas in cells pretreated with detergent, noisy signal made reliable detection impossible. ELISA showed positive results in few serums. The low number of NMOSD serums included in our study reduces its power to conclude the specificity of AQP1 antibodies as new biomarkers of NMOSD. Our study does not sustain detection of anti-AQP1 in serum of NMOSD patients but further experiments are expected. PMID:27455255

  15. Paucity of natural killer and cytotoxic T cells in human neuromyelitis optica lesions.

    PubMed

    Saadoun, Samira; Bridges, Leslie R; Verkman, A S; Papadopoulos, Marios C

    2012-12-19

    Neuromyelitis optica is a severe inflammatory demyelinating disease of the central nervous system. Most patients with neuromyelitis optica have circulating immunoglobulin G (IgG) antibodies against the astrocytic water channel protein aquaporin-4 (AQP4), which are pathogenic. Anti-AQP4 IgG-mediated complement-dependent astrocyte toxicity is a key mechanism of central nervous system damage in neuromyelitis optica, but the role of natural killer and cytotoxic T cells is unknown. Our objective was to determine whether natural killer and cytotoxic T cells play a role in human neuromyelitis optica lesions. We immunostained four actively demyelinating lesions, obtained from patients with anti-AQP4 IgG positive neuromyelitis optica, for Granzyme B and Perforin. The inflammatory cells were perivascular neutrophils, eosinophils and macrophages, with only occasional Granzyme B+ or Perforin+ cells. Greater than 95% of inflamed vessels in each lesion had no surrounding Granzyme B+ or Perforin+ cells. Granzyme B+ or Perforin+ cells were abundant in human spleen (positive control). Although natural killer cells produce central nervous system damage in mice injected with anti-AQP4 IgG, our findings here indicate that natural killer-mediated and T cell-mediated cytotoxicity are probably not involved in central nervous system damage in human neuromyelitis optica.

  16. Syndrome of inappropriate antidiuretic hormone secretion in patients with aquaporin-4 antibody.

    PubMed

    Pu, Shuxiang; Long, Youming; Yang, Ning; He, Yihua; Shan, Fulan; Fan, Yongxiang; Yin, Jianrui; Gao, Qingchun; Cong, Gao

    2015-01-01

    The objective of this study was to analyze the frequency of syndrome of inappropriate antidiuretic hormone secretion (SIADH) in patients with positive aquaporin-4 (AQP4) antibodies and evaluate the relationship between SIADH and hypothalamic lesions in patients with NMO and NMO spectrum disorder (NMOSD). AQP4 antibodies were tested by an indirect immunofluorescence assay employing HEK-293 cells transfected with recombinant human AQP4. Clinical data of patients were analyzed retrospectively. In total, 192 patients with AQP4 antibodies were certified, of which 41 patients (21.4 %) were included in the present study. Six patients (14.6 %, 6/41) met the criteria of SIADH, of which hyponatremia was mild in one patient, and severe in five. Five patients experienced confusion or decreased consciousness. Four patients were diagnosed with NMO and two were diagnosed with recurrent optic neuritis. Magnetic resonance imaging showed 11 of 41 patients (26.8 %) had hypothalamic lesions. All patients with SIADH had hypothalamic abnormalities. Hyponatremia resolved in all patients after intravenous methylprednisolone and intravenous immunoglobulin therapy. SIADH is not rare in patients with NMO/NMOSD, especially in patients with lesions close to the hypothalamus.

  17. Anti-aquaporin-4 antibodies in Devic’s neuromyelitis optica: therapeutic implications

    PubMed Central

    Marignier, Romain; Giraudon, Pascale; Vukusic, Sandra; Confavreux, Christian; Honnorat, Jérôme

    2010-01-01

    Devic’s neuromyelitis optica (DNMO) is a demyelinating and inflammatory disease of the central nervous system (CNS) essentially restricted to the spinal cord and the optic nerves. It is a rare disorder with a prevalence estimated at less than 1/100,000 in Western countries. Since the first description by Eugène Devic in 1894, the relationship between DNMO and multiple sclerosis (MS) has been controversial. Recent clinical, epidemiological, pathological and immunological data demonstrate that MS and DNMO are distinct entities. This distinction between DNMO and MS is crucial, as prognosis and treatment are indeed different. DNMO is now considered to be an autoimmune, antibody-mediated disease especially since the identification of a specific serum autoantibody, named NMO-IgG and directed against the main water channel of the CNS, aquaporin-4 (AQP4). The assessment of AQP4 antibodies (Abs) has initially been proposed to differentiate DNMO and MS. It has also enlarged the clinical spectrum of DNMO and proved to be helpful in predicting relapses and conversion to DNMO after a first episode of longitudinally extensive transverse myelitis or isolated optic neuritis. Lastly, the discovery of the pathogenic role of AQP4 Abs in DNMO leads to a better understanding of detailed DNMO immunopathology and the elaboration of relevant novel treatment strategies specific to DNMO. In this review, we summarize the present and future therapeutic implications generated by the discovery of the various pathogenic mechanisms of AQP4 Abs in DNMO pathophysiology. PMID:21179621

  18. Aquaporin 1 and aquaporin 4 overexpression in bovine spongiform encephalopathy in a transgenic murine model and in cattle field cases.

    PubMed

    Costa, Carme; Tortosa, Raül; Rodríguez, Agustín; Ferrer, Isidre; Torres, Juan Maria; Bassols, Anna; Pumarola, Martí

    2007-10-17

    Aquaporins (AQP) are a family of transmembrane proteins that act as water selective channels. AQP1 and AQP4 are widely expressed in the central nervous system where they play several roles. Overexpression of AQP has been reported in some human and animal transmissible spongiform encephalopathies, but information is scanty about their distribution in the central nervous system in bovine spongiform encephalopathy (BSE). Double immunohistochemistry for AQP1, AQP4 and GFAP was developed in a transgenic mouse line overexpressing the bovine cellular prion protein (BoTg110), intracerebrally infected with cattle BSE. Western blot for AQP1 and AQP4, and immunohistochemistry for both AQP and GFAP were carried out in cases of BSE-diagnosed cattle as part of surveillance plan in Catalonia (Spain). A marked increase in AQP1 and AQP4 was observed in mice at the terminal stage of the disease, when they had a wide range of clinical signs, whereas no increase could be observed in the early stage before the onset of the clinical signs. In cattle which did not show evidence of clinical signs, both AQP already showed a great increase. The AQP overexpression correlated with GFAP-immunoreactive astrocytes and PrPres deposition in both cases. The results of this study suggest that AQP overexpression in glial cells could lead to an imbalance in water and ion homeostasis which could contribute to triggering the typical histopathological changes of BSE.

  19. Aquaporins in Brain Edema and Neuropathological Conditions

    PubMed Central

    Filippidis, Aristotelis S.; Carozza, Richard B.; Rekate, Harold L.

    2016-01-01

    The aquaporin (AQP) family of water channels are a group of small, membrane-spanning proteins that are vital for the rapid transport of water across the plasma membrane. These proteins are widely expressed, from tissues such as the renal epithelium and erythrocytes to the various cells of the central nervous system. This review will elucidate the basic structure and distribution of aquaporins and discuss the role of aquaporins in various neuropathologies. AQP1 and AQP4, the two primary aquaporin molecules of the central nervous system, regulate brain water and CSF movement and contribute to cytotoxic and vasogenic edema, where they control the size of the intracellular and extracellular fluid volumes, respectively. AQP4 expression is vital to the cellular migration and angiogenesis at the heart of tumor growth; AQP4 is central to dysfunctions in glutamate metabolism, synaptogenesis, and memory consolidation; and AQP1 and AQP4 adaptations have been seen in obstructive and non-obstructive hydrocephalus and may be therapeutic targets. PMID:28036023

  20. The Cancer Drug Tamoxifen: A Potential Therapeutic Treatment for Spinal Cord Injury

    PubMed Central

    Guptarak, Jutatip; Wiktorowicz, John E.; Sadygov, Rovshan G.; Zivadinovic, Dragoslava; Paulucci-Holthauzen, Adriana A.; Vergara, Leoncio

    2014-01-01

    Abstract Tamoxifen (TMX) is a selective estrogen receptor modulator that can mimic the neuroprotective effects of estrogen but lacks its systemic adverse effects. We found that TMX (1 mg/day) significantly improved the motor recovery of partially paralyzed hind limbs of male adult rats with thoracic spinal cord injury (SCI), thus indicating a translational potential for this cancer medication given its clinical safety and applicability and the lack of currently available treatments for SCI. To shed light on the mechanisms underlying the beneficial effects of TMX for SCI, we used proteomic analyses, Western blots and histological assays, which showed that TMX treatment spared mature oligodendrocytes/increased myelin levels and altered reactive astrocytes, including the upregulation of the water channels aquaporin 4 (AQP4), a novel finding. AQP4 increases in TMX-treated SCI rats were associated with smaller fluid-filled cavities with borders consisting of densely packed AQP4-expressing astrocytes that closely resemble the organization of normal glia limitans externa (in contrast to large cavities in control SCI rats that lacked glia limitans-like borders and contained reactive glial cells). Based on our findings, we propose that TMX is a promising candidate for the therapeutic treatment of SCI and a possible intervention for other neuropathological conditions associated with demyelination and AQP4 dysfunction. PMID:24004276

  1. In Vitro Acid-Mediated Initial Dental Enamel Loss Is Associated with Genetic Variants Previously Linked to Caries Experience.

    PubMed

    Vieira, Alexandre R; Bayram, Merve; Seymen, Figen; Sencak, Regina C; Lippert, Frank; Modesto, Adriana

    2017-01-01

    We have previously shown that AQP5 and BTF3 genetic variation and expression in whole saliva are associated with caries experience suggesting that these genes may have a functional role in protecting against caries. To further explore these results, we tested ex vivo if variants in these genes are associated with subclinical dental enamel mineral loss. DNA and enamel samples were obtained from 53 individuals. Enamel samples were analyzed for Knoop hardness of sound enamel, integrated mineral loss after subclinical carious lesion creation, and change in integrated mineral loss after remineralization. DNA samples were genotyped for single nucleotide polymorphisms using TaqMan chemistry. Chi-square and Fisher's exact tests were used to compare individuals above and below the mean sound enamel microhardness of the cohort with alpha of 0.05. The A allele of BTF3 rs6862039 appears to be associated with harder enamel at baseline (p = 0.09), enamel more resistant to demineralization (p = 0.01), and enamel that more efficiently regain mineral and remineralize (p = 0.04). Similarly, the G allele of AQP5 marker rs3759129 and A allele of AQP5 marker rs296763 are associated with enamel more resistant to demineralization (p = 0.03 and 0.05, respectively). AQP5 and BTF3 genetic variations influence the initial subclinical stages of caries lesion formation in the subsurface of enamel.

  2. In Vitro Acid-Mediated Initial Dental Enamel Loss Is Associated with Genetic Variants Previously Linked to Caries Experience

    PubMed Central

    Vieira, Alexandre R.; Bayram, Merve; Seymen, Figen; Sencak, Regina C.; Lippert, Frank; Modesto, Adriana

    2017-01-01

    We have previously shown that AQP5 and BTF3 genetic variation and expression in whole saliva are associated with caries experience suggesting that these genes may have a functional role in protecting against caries. To further explore these results, we tested ex vivo if variants in these genes are associated with subclinical dental enamel mineral loss. DNA and enamel samples were obtained from 53 individuals. Enamel samples were analyzed for Knoop hardness of sound enamel, integrated mineral loss after subclinical carious lesion creation, and change in integrated mineral loss after remineralization. DNA samples were genotyped for single nucleotide polymorphisms using TaqMan chemistry. Chi-square and Fisher's exact tests were used to compare individuals above and below the mean sound enamel microhardness of the cohort with alpha of 0.05. The A allele of BTF3 rs6862039 appears to be associated with harder enamel at baseline (p = 0.09), enamel more resistant to demineralization (p = 0.01), and enamel that more efficiently regain mineral and remineralize (p = 0.04). Similarly, the G allele of AQP5 marker rs3759129 and A allele of AQP5 marker rs296763 are associated with enamel more resistant to demineralization (p = 0.03 and 0.05, respectively). AQP5 and BTF3 genetic variations influence the initial subclinical stages of caries lesion formation in the subsurface of enamel. PMID:28275354

  3. Indoxyl Sulfate as a Mediator Involved in Dysregulation of Pulmonary Aquaporin-5 in Acute Lung Injury Caused by Acute Kidney Injury

    PubMed Central

    Yabuuchi, Nozomi; Sagata, Masataka; Saigo, Chika; Yoneda, Go; Yamamoto, Yuko; Nomura, Yui; Nishi, Kazuhiko; Fujino, Rika; Jono, Hirofumi; Saito, Hideyuki

    2016-01-01

    High mortality of acute kidney injury (AKI) is associated with acute lung injury (ALI), which is a typical complication of AKI. Although it is suggested that dysregulation of lung salt and water channels following AKI plays a pivotal role in ALI, the mechanism of its dysregulation has not been elucidated. Here, we examined the involvement of a typical oxidative stress-inducing uremic toxin, indoxyl sulfate (IS), in the dysregulation of the pulmonary predominant water channel, aquaporin 5 (AQP-5), in bilateral nephrectomy (BNx)-induced AKI model rats. BNx evoked AKI with the increases in serum creatinine (SCr), blood urea nitrogen (BUN) and serum IS levels and exhibited thickening of interstitial tissue in the lung. Administration of AST-120, clinically-used oral spherical adsorptive carbon beads, resulted in a significant decrease in serum IS level and thickening of interstitial tissue, which was accompanied with the decreases in IS accumulation in various tissues, especially lung. Interestingly, a significant decrease in AQP-5 expression of lung was observed in BNx rats. Moreover, the BNx-induced decrease in pulmonary AQP-5 protein expression was markedly restored by oral administration of AST-120. These results suggest that BNx-induced AKI causes dysregulation of pulmonary AQP-5 expression, in which IS could play a toxico-physiological role as a mediator involved in renopulmonary crosstalk. PMID:28025487

  4. Indoxyl Sulfate as a Mediator Involved in Dysregulation of Pulmonary Aquaporin-5 in Acute Lung Injury Caused by Acute Kidney Injury.

    PubMed

    Yabuuchi, Nozomi; Sagata, Masataka; Saigo, Chika; Yoneda, Go; Yamamoto, Yuko; Nomura, Yui; Nishi, Kazuhiko; Fujino, Rika; Jono, Hirofumi; Saito, Hideyuki

    2016-12-23

    High mortality of acute kidney injury (AKI) is associated with acute lung injury (ALI), which is a typical complication of AKI. Although it is suggested that dysregulation of lung salt and water channels following AKI plays a pivotal role in ALI, the mechanism of its dysregulation has not been elucidated. Here, we examined the involvement of a typical oxidative stress-inducing uremic toxin, indoxyl sulfate (IS), in the dysregulation of the pulmonary predominant water channel, aquaporin 5 (AQP-5), in bilateral nephrectomy (BNx)-induced AKI model rats. BNx evoked AKI with the increases in serum creatinine (SCr), blood urea nitrogen (BUN) and serum IS levels and exhibited thickening of interstitial tissue in the lung. Administration of AST-120, clinically-used oral spherical adsorptive carbon beads, resulted in a significant decrease in serum IS level and thickening of interstitial tissue, which was accompanied with the decreases in IS accumulation in various tissues, especially lung. Interestingly, a significant decrease in AQP-5 expression of lung was observed in BNx rats. Moreover, the BNx-induced decrease in pulmonary AQP-5 protein expression was markedly restored by oral administration of AST-120. These results suggest that BNx-induced AKI causes dysregulation of pulmonary AQP-5 expression, in which IS could play a toxico-physiological role as a mediator involved in renopulmonary crosstalk.

  5. Lactuside B decreases aquaporin-4 and caspase-3 mRNA expression in the hippocampus and striatum following cerebral ischaemia-reperfusion injury in rats

    PubMed Central

    LI, PING-FA; ZHAN, HE-QIN; LI, SHENG-YING; LIU, RUI-LI; YAN, FU-LIN; CUI, TAI-ZHEN; YANG, YU-PING; LI, PENG; WANG, XIN-YAO

    2014-01-01

    This study aimed to investigate the effects of lactuside B (LB) on aquaporin-4 (AQP4) and caspase-3 mRNA expression in the hippocampus and the striatum following cerebral ischaemia-reperfusion (I/R) injury in rats. Cerebral I/R injury was established in Sprague-Dawley rats by occluding the middle cerebral artery for 2 h and then inducing reperfusion. Rats in the I/R + LB groups were treated with various doses of LB following reperfusion. Neurological deficit scores and brain water content were obtained to determine the pharmacodynamics of LB. Reverse transcription polymerase chain reaction was performed to determine the expression levels of AQP4 and caspase-3 mRNA in the hippocampus and the striatum. The results of the present study indicate that LB decreased the neurological deficit scores and the brain water content. In the hippocampus, AQP4 and caspase-3 mRNA expression levels were significantly downregulated in the I/R + LB groups at 24 and 72 h following drug administration, compared with those in the I/R group (P<0.05). In the striatum, LB was also shown to significantly reduce AQP4 and caspase-3 mRNA expression levels at 24 and 72 h following drug administration, compared with those in the I/R group (P<0.05). The effects became stronger as the LB dose was increased. The most significant reductions in AQP4 and caspase-3 mRNA expression were noted in the I/R + LB 25 mg/kg and I/R + LB 50 mg/kg groups at 72 h following drug administration. The results of the present study show that LB is capable of significantly downregulating AQP4 and caspase-3 mRNA expression in the hippocampus and striatum following cerebral I/R injury in rats. The mechanism by which LB improved ischaemic brain injury may be associated with changes in AQP4 and caspase-3 mRNA expression in the hippocampus and the striatum. PMID:24520266

  6. Neuromyelitis optica spectrum disorders

    PubMed Central

    Sepúlveda, Maria; Armangué, Thaís; Sola-Valls, Nuria; Arrambide, Georgina; Meca-Lallana, José E.; Oreja-Guevara, Celia; Mendibe, Mar; Alvarez de Arcaya, Amaya; Aladro, Yolanda; Casanova, Bonaventura; Olascoaga, Javier; Jiménez-Huete, Adolfo; Fernández-Fournier, Mireya; Ramió-Torrentà, Lluis; Cobo-Calvo, Alvaro; Viñals, Montserrat; de Andrés, Clara; Meca-Lallana, Virginia; Cervelló, Angeles; Calles, Carmen; Rubio, Manuel Barón; Ramo-Tello, Cristina; Caminero, Ana; Munteis, Elvira; Antigüedad, Alfredo R.; Blanco, Yolanda; Villoslada, Pablo; Montalban, Xavier; Graus, Francesc

    2016-01-01

    Objective: To (1) determine the value of the recently proposed criteria of neuromyelitis optica (NMO) spectrum disorder (NMOSD) that unify patients with NMO and those with limited forms (NMO/LF) with aquaporin-4 immunoglobulin G (AQP4-IgG) antibodies; and (2) investigate the clinical significance of the serologic status in patients with NMO. Methods: This was a retrospective, multicenter study of 181 patients fulfilling the 2006 NMO criteria (n = 127) or NMO/LF criteria with AQP4-IgG (n = 54). AQP4-IgG and myelin oligodendrocyte glycoprotein immunoglobulin G (MOG-IgG) antibodies were tested using cell-based assays. Results: Patients were mainly white (86%) and female (ratio 6.5:1) with median age at onset 39 years (range 10–77). Compared to patients with NMO and AQP4-IgG (n = 94), those with NMO/LF presented more often with longitudinally extensive transverse myelitis (LETM) (p < 0.001), and had lower relapse rates (p = 0.015), but similar disability outcomes. Nonwhite ethnicity and optic neuritis presentation doubled the risk for developing NMO compared with white race (p = 0.008) or LETM presentation (p = 0.008). Nonwhite race (hazard ratio [HR] 4.3, 95% confidence interval [CI] 1.4–13.6) and older age at onset were associated with worse outcome (for every 10-year increase, HR 1.7, 95% CI 1.3–2.2). Patients with NMO and MOG-IgG (n = 9) had lower female:male ratio (0.8:1) and better disability outcome than AQP4-IgG-seropositive or double-seronegative patients (p < 0.001). Conclusions: In patients with AQP4-IgG, the similar outcomes regardless of the clinical phenotype support the unified term NMOSD; nonwhite ethnicity and older age at onset are associated with worse outcome. Double-seronegative and AQP4-IgG-seropositive NMO have a similar clinical outcome. The better prognosis of patients with MOG-IgG and NMO suggests that phenotypic and serologic classification is useful. PMID:27144216

  7. Automated cell-based assay for screening of aquaporin inhibitors.

    PubMed

    Mola, Maria Grazia; Nicchia, Grazia Paola; Svelto, Maria; Spray, David C; Frigeri, Antonio

    2009-10-01

    Aquaporins form water channels that play major roles in a variety of physiological processes so that altered expression or function may underlie pathological conditions. In order to identify compounds that modulate aquaporin function, we have implemented a functional assay based on rapid measurement of osmotically induced cell volume changes to screen several libraries of diverse drugs. The time course of fluorescence changes in calcein-loaded cells was analyzed during an osmotic challenge using a 96-multiwell fluorescence plate reader. This system was validated using astrocyte primary cultures and fibroblasts that strongly express endogenous AQP4 and AQP1 proteins, respectively, as well as AQP4-transfected cells. We screened 3575 compounds, including 418 FDA-approved and commercially available drugs, for their effect on AQP-mediated water transport. Primary screening yielded 10 compounds that affected water transport activity in both astrocytes and AQP4-transfected cells and 42 compounds that altered cell volume regulation in astrocytes. Selected drugs were then analyzed on AQP1-expressing erythrocytes and AQP4-expressing membrane vesicles by stopped-flow light scattering. Four molecules of the National Cancer Institute's chemical library (NSC164914, NSC670229, NSC168597, NSC301460) were identified that differentially affected both AQP4 and AQP1 mediated water transport, with EC50 values between 20 and 50 microM. This fluorescence microplate reader-based assay may, thus, provide a platform for high-throughput screening which, when coupled to a secondary evaluation to confirm target specificity, should allow discovery of AQP-specific compounds for novel therapeutic strategies in the treatment of water balance disorders.

  8. Automated Cell-Based Assay for Screening of Aquaporin Inhibitors

    PubMed Central

    Mola, Maria Grazia; Nicchia, Grazia Paola; Svelto, Maria; Spray, David C.; Frigeri, Antonio

    2010-01-01

    Aquaporins form water channels that play major roles in a variety of physiological processes so that altered expression or function may underlie pathological conditions. In order to identify compounds that modulate aquaporin function, we have implemented a functional assay based on rapid measurement of osmotically induced cell volume changes to screen several libraries of diverse drugs. The time course of fluorescence changes in calcein-loaded cells was analyzed during an osmotic challenge using a 96-multiwell fluorescence plate reader. This system was validated using astrocyte primary cultures and fibroblasts that strongly express endogenous AQP4 and AQP1 proteins, respectively, as well as AQP4-transfected cells. We screened 3575 compounds, including 418 FDA-approved and commercially available drugs, for their effect on AQP-mediated water transport. Primary screening yielded 10 compounds that affected water transport activity in both astrocytes and AQP4-transfected cells and 42 compounds that altered cell volume regulation in astrocytes. Selected drugs were then analyzed on AQP1-expressing erythrocytes and AQP4-expressing membrane vesicles by stopped-flow light scattering. Four molecules of the National Cancer Institute's chemical library (NSC164914, NSC670229, NSC168597, NSC301460) were identified that differentially affected both AQP4 and AQP1 mediated water transport, with EC50 values between 20 and 50 μM. This fluorescence microplate reader-based assay may, thus, provide a platform for high-throughput screening which, when coupled to a secondary evaluation to confirm target specificity, should allow discovery of AQP-specific compounds for novel therapeutic strategies in the treatment of water balance disorders. PMID:19705854

  9. Effects of metformin treatment on glioma-induced brain edema

    PubMed Central

    Zhao, Bin; Wang, Xiaoke; Zheng, Jun; Wang, Hailiang; Liu, Jun

    2016-01-01

    Considerable evidence has demonstrated that metformin can activate 5’-AMP-activated protein kinase (AMPK) signaling pathway, which plays a critical role in protection of endothelial cell permeability. Hence, the present study evaluated the effects of metformin on blood brain barrier permeability and AQP4 expression in vitro, and assessed the effects of metformin treatment on tumor-induced brain edema in vivo. Hypoxia or VEGF exposure enhanced bEnd3 endothelial cell monolayer permeability and attenuated the expression of tight junction proteins including Occludin, Claudin-5, ZO-1, and ZO-2. However, 0.5 mM metformin treatment protected bEnd3 endothelial cell monolayer from hypoxia or VEGF-induced permeability, which was correlated with increased expression of tight junction proteins. Furthermore, metformin treatment attenuated AQP4 protein expression in cultured astrocytes. Such an effect involved the activation of AMPK and inhibition of NF-κB. Finally, metformin treatment dose-dependently reduced glioma induced vascular permeability and cerebral edema in vivo in rats. Thus, our results suggested that metformin may protect endothelial cell tight junction, prevent damage to the blood brain barrier induced by brain tumor growth, and alleviate the formation of cerebral edema. Furthermore, since the formation of cytotoxic edema and AQP4 expression was positively correlated, our results indicated that metformin may reduce the formation of cytotoxic edema. However, given that AQP4 plays a key role in the elimination of cerebral edema, attenuation of AQP4 expression by metformin may reduce the elimination of cerebral edema. Hence, future studies will be necessary to dissect the specific mechanisms of metformin underlying the dynamics of tumor-induced brain edema in vivo. PMID:27648126

  10. Effects of metformin treatment on glioma-induced brain edema.

    PubMed

    Zhao, Bin; Wang, Xiaoke; Zheng, Jun; Wang, Hailiang; Liu, Jun

    2016-01-01

    Considerable evidence has demonstrated that metformin can activate 5'-AMP-activated protein kinase (AMPK) signaling pathway, which plays a critical role in protection of endothelial cell permeability. Hence, the present study evaluated the effects of metformin on blood brain barrier permeability and AQP4 expression in vitro, and assessed the effects of metformin treatment on tumor-induced brain edema in vivo. Hypoxia or VEGF exposure enhanced bEnd3 endothelial cell monolayer permeability and attenuated the expression of tight junction proteins including Occludin, Claudin-5, ZO-1, and ZO-2. However, 0.5 mM metformin treatment protected bEnd3 endothelial cell monolayer from hypoxia or VEGF-induced permeability, which was correlated with increased expression of tight junction proteins. Furthermore, metformin treatment attenuated AQP4 protein expression in cultured astrocytes. Such an effect involved the activation of AMPK and inhibition of NF-κB. Finally, metformin treatment dose-dependently reduced glioma induced vascular permeability and cerebral edema in vivo in rats. Thus, our results suggested that metformin may protect endothelial cell tight junction, prevent damage to the blood brain barrier induced by brain tumor growth, and alleviate the formation of cerebral edema. Furthermore, since the formation of cytotoxic edema and AQP4 expression was positively correlated, our results indicated that metformin may reduce the formation of cytotoxic edema. However, given that AQP4 plays a key role in the elimination of cerebral edema, attenuation of AQP4 expression by metformin may reduce the elimination of cerebral edema. Hence, future studies will be necessary to dissect the specific mechanisms of metformin underlying the dynamics of tumor-induced brain edema in vivo.

  11. Glymphatic fluid transport controls paravascular clearance of AAV vectors from the brain

    PubMed Central

    Murlidharan, Giridhar; Crowther, Andrew; Reardon, Rebecca A.; Song, Juan

    2016-01-01

    Adeno-associated viruses (AAV) are currently being evaluated in clinical trials for gene therapy of CNS disorders. However, host factors that influence the spread, clearance, and transduction efficiency of AAV vectors in the brain are not well understood. Recent studies have demonstrated that fluid flow mediated by aquaporin-4 (AQP4) channels located on astroglial end feet is essential for exchange of solutes between interstitial and cerebrospinal fluid. This phenomenon, which is essential for interstitial clearance of solutes from the CNS, has been termed glial-associated lymphatic transport or glymphatic transport. In the current study, we demonstrate that glymphatic transport profoundly affects various aspects of AAV gene transfer in the CNS. Altered localization of AQP4 in aged mouse brains correlated with significantly increased retention of AAV vectors in the parenchyma and reduced systemic leakage following ventricular administration. We observed a similar increase in AAV retention and transgene expression upon i.c.v. administration in AQP4–/– mice. Consistent with this observation, fluorophore-labeled AAV vectors showed markedly reduced flux from the ventricles of AQP4–/– mice compared with WT mice. These results were further corroborated by reduced AAV clearance from the AQP4-null brain, as demonstrated by reduced transgene expression and vector genome accumulation in systemic organs. We postulate that deregulation of glymphatic transport in aged and diseased brains could markedly affect the parenchymal spread, clearance, and gene transfer efficiency of AAV vectors. Assessment of biomarkers that report the kinetics of CSF flux in prospective gene therapy patients might inform variable treatment outcomes and guide future clinical trial design. PMID:27699236

  12. Immunology of neuromyelitis optica during pregnancy

    PubMed Central

    Davoudi, Vahid; Keyhanian, Kiandokht; Bove, Riley M.

    2016-01-01

    Anti–aquaporin-4 (AQP4) autoantibody plays a key role in the pathogenesis of neuromyelitis optica (NMO). Studies have shown increased relapse rates in patients with NMO during pregnancy and postpartum. High estrogen levels during pregnancy can increase activation-induced cytidine deaminase expression, which is responsible for immunoglobulin production. Additionally, sex hormones may influence antibody glycosylation, with effects on antibody function. Estrogen decreases apoptosis of self-reactive B cells, through upregulation of antiapoptotic molecules. Furthermore, high estrogen levels during pregnancy can boost B-cell activating factor and type 1 interferon (IFN) production, facilitating development of self-reactive peripheral B cells in association with increased disease activity. Elevated levels of estrogen during pregnancy decrease IFN-γ generation, which causes a shift toward T helper (Th) 2 immunity, thereby propagating NMO pathogenesis. Women with NMO have an elevated rate of pregnancy complications including miscarriage and preeclampsia, which are associated with increased Th17 cells and reduction of T-regulatory cells. These in turn can enhance inflammation in NMO. Increased regulatory natural killer cells (CD56−) during pregnancy can enhance Th2-mediated immunity, thereby increasing inflammation. In the placenta, trophoblasts express AQP4 antigen and are exposed to maternal blood containing anti-AQP4 antibodies. Animal models have shown that anti-AQP4 antibodies can bind to AQP4 antigen in placenta leading to complement deposition and placental necrosis. Reduction of regulatory complements has been associated with placental insufficiency, and it is unclear whether these are altered in NMO. Further studies are required to elucidate the specific mechanisms of disease worsening, as well as the increased rate of complications during pregnancy in women with NMO. PMID:27761482

  13. Glymphatic fluid transport controls paravascular clearance of AAV vectors from the brain.

    PubMed

    Murlidharan, Giridhar; Crowther, Andrew; Reardon, Rebecca A; Song, Juan; Asokan, Aravind

    2016-09-08

    Adeno-associated viruses (AAV) are currently being evaluated in clinical trials for gene therapy of CNS disorders. However, host factors that influence the spread, clearance, and transduction efficiency of AAV vectors in the brain are not well understood. Recent studies have demonstrated that fluid flow mediated by aquaporin-4 (AQP4) channels located on astroglial end feet is essential for exchange of solutes between interstitial and cerebrospinal fluid. This phenomenon, which is essential for interstitial clearance of solutes from the CNS, has been termed glial-associated lymphatic transport or glymphatic transport. In the current study, we demonstrate that glymphatic transport profoundly affects various aspects of AAV gene transfer in the CNS. Altered localization of AQP4 in aged mouse brains correlated with significantly increased retention of AAV vectors in the parenchyma and reduced systemic leakage following ventricular administration. We observed a similar increase in AAV retention and transgene expression upon i.c.v. administration in AQP4(-/-) mice. Consistent with this observation, fluorophore-labeled AAV vectors showed markedly reduced flux from the ventricles of AQP4(-/-) mice compared with WT mice. These results were further corroborated by reduced AAV clearance from the AQP4-null brain, as demonstrated by reduced transgene expression and vector genome accumulation in systemic organs. We postulate that deregulation of glymphatic transport in aged and diseased brains could markedly affect the parenchymal spread, clearance, and gene transfer efficiency of AAV vectors. Assessment of biomarkers that report the kinetics of CSF flux in prospective gene therapy patients might inform variable treatment outcomes and guide future clinical trial design.

  14. Colon water transport in transgenic mice lacking aquaporin-4 water channels

    PubMed Central

    WANG, KASPER S.; MA, TONGHUI; FILIZ, FERDA; VERKMAN, A. S.; BASTIDAS, J. AUGUSTO

    2012-01-01

    Transgenic null mice were used to test the hypothesis that water channel aquaporin-4 (AQP4) is involved in colon water transport and fecal dehydration. AQP4 was immunolocalized to the basolateral membrane of colonic surface epithelium of wild-type (+/+) mice and was absent in AQP4 null (−/−) mice. The transepithelial osmotic water permeability coefficient (Pf) of in vivo perfused colon of +/+ mice, measured using the volume marker 14C-labeled polyethylene glycol, was 0.016 ± 0.002 cm/s. Pf of proximal colon was greater than that of distal colon (0.020 ± 0.004 vs. 0.009 ± 0.003 cm/s, P < 0.01). Pf was significantly lower in −/− mice when measured in full-length colon (0.009 ± 0.002 cm/s, P < 0.05) and proximal colon (0.013 ± 0.002 cm/s, P < 0.05) but not in distal colon. There was no difference in water content of cecal stool from +/+ vs. −/− mice (0.80 ± 0.01 vs. 0.81 ± 0.01), but there was a slightly higher water content in defecated stool from +/+ mice (0.68 ± 0.01 vs. 0.65 ± 0.01, P < 0.05). Despite the differences in water permeability with AQP4 deletion, theophylline-induced secretion was not impaired (50 ± 9 vs. 51 ± 8 μl · min−1 · g−1). These results provide evidence that transcellular water transport through AQP4 water channels in colonic epithelium facilitates transepithelial osmotic water permeability but has little or no effect on colonic fluid secretion or fecal dehydration. PMID:10915657

  15. Glial molecular alterations with mouse brain development and aging: up-regulation of the Kir4.1 and aquaporin-4.

    PubMed

    Gupta, Rajaneesh Kumar; Kanungo, Madhusudan

    2013-02-01

    Glial cells, besides participating as passive supporting matrix, are also proposed to be involved in the optimization of the interstitial space for synaptic transmission by tight control of ionic and water homeostasis. In adult mouse brain, inwardly rectifying K+ (Kir4.1) and aquaporin-4 (AQP4) channels localize to astroglial endfeets in contact with brain microvessels and glutamate synapses, optimizing clearance of extracellular K(+) and water from the synaptic layers. However, it is still unclear whether there is an age-dependent difference in the expressions of Kir4.1 and AQP4 channels specifically during postnatal development and aging when various marked changes occur in brain and if these changes region specific. RT-PCR and immunoblotting was conducted to compare the relative expression of Kir4.1 and AQP4 mRNA and protein in the early and mature postnatal (0-, 15-, 45-day), adult (20-week), and old age (70-week) mice cerebral and cerebellar cortices. Expressions of Kir4.1 and AQP4 mRNA and protein are very low at 0-day. A pronounced and continuous increase was observed by mature postnatal ages (15-, 45-days). However, in the 70-week-old mice, expressions are significantly up-regulated as compared to 20-week-old mice. Both genes follow the same age-related pattern in both cerebral and cerebellar cortices. The time course and expression pattern suggests that Kir4.1 and AQP4 channels may play an important role in brain K(+) and water homeostasis in early postnatal weeks after birth and during aging.

  16. The Prevalence of Anti-Aquaporin 4 Antibody in Patients with Idiopathic Inflammatory Demyelinating Diseases Presented to a Tertiary Hospital in Malaysia: Presentation and Prognosis

    PubMed Central

    Tan, C. T.

    2017-01-01

    Background. There have been inconsistent reports on the prevalence and pathogenicity of anti-Aquaporin 4 (AQP4) in patients presented with idiopathic inflammatory demyelinating diseases (IIDDs). Objective. To estimate the prevalence of anti-AQP4 antibody in patients with IIDDs presented to University Malaya Medical Centre in terms of patients' clinical and radiological presentations and prognoses. Methods. Retrospective data review of IIDDs patients presented from 2005 to 2015. Patients were classified into classical multiple sclerosis (CMS), opticospinal (OS) presentation, optic neuritis (ON), transverse myelitis (TM), brainstem syndrome (BS), and tumefactive MS. Anti-Aquaporin 4 antibody was tested using the Indirect Immunofluorescence Test (IIFT) cell-based assay. Statistical analysis was done using the SPSS version 20. Results. Anti-AQP4 antibody was detected in 53% of patients presented with IIDDs. CMS was more common in the seronegative group, 27/47 (57.45%; p < 0.001). Conversely, OS involvement was more common in the seropositive group, 26/53 (49.06%; p < 0.001). Longitudinally extensive spinal cord lesions (LESCLs) on MRI were also more common in the seropositive group, 29/40 (72.50%; p = 0.004). Only 2/40 (5.00%) had MRI evidence of patchy or multiple short-segment spinal cord lesions in the AQP4-positive group (p = 0.003). The relapse rate and Expanded Disability Status Scale (EDSS) were also higher in the seropositive group (5.43 versus 3.17, p = 0.005; 4.07 versus 2.51, p = 0.006, resp.). Typical clinical presentations that defined NMO were also seen in the seronegative patients, but in a lower frequency. Conclusion. Our cohort of patients had a higher prevalence of seropositivity of anti-AQP4 antibody as compared to those in Western countries. This was also associated with a more typical presentation of opticospinal involvement with LESCLs on MRI, a higher rate of relapse, and EDSS. PMID:28203460

  17. Immunohistochemical localization and mRNA expression of aquaporins in the macula utriculi of patients with Meniere's disease and acoustic neuroma.

    PubMed

    Ishiyama, Gail; Lopez, Ivan A; Beltran-Parrazal, Luis; Ishiyama, Akira

    2010-06-01

    Meniere's disease is nearly invariably associated with endolymphatic hydrops (the net accumulation of water in the inner ear endolymphatic space). Vestibular maculae utriculi were acquired from patients undergoing surgery for Meniere's disease and acoustic neuroma and from autopsy (subjects with normal hearing and balance). Quantitative immunostaining was conducted with antibodies against aquaporins (AQPs) 1, 4, and 6, Na(+)K(+)ATPase, Na(+)K(+)2Cl co-transporter (NKCC1), and alpha-syntrophin. mRNA was extracted from the surgically acquired utricles from subjects with Meniere's disease and acoustic neuroma to conduct quantitative real-time reverse transcription with polymerase chain reaction for AQP1, AQP4, and AQP6. AQP1 immunoreactivity (-IR) was located in blood vessels and fibrocytes in the underlying stroma, without any apparent alteration in Meniere's specimens when compared with acoustic neuroma and autopsy specimens. AQP4-IR localized to the epithelial basolateral supporting cells in Meniere's disease, acoustic neuroma, and autopsy. In specimens from subjects with Meniere's disease, AQP4-IR was significantly decreased compared with autopsy and acoustic neuroma specimens. AQP6-IR occurred in the sub-apical vestibular supporting cells in acoustic neuroma and autopsy samples. However, in Meniere's disease specimens, AQP6-IR was significantly increased and diffusely redistributed throughout the supporting cell cytoplasm. Na(+)K(+)ATPase, NKCC1, and alpha-syntrophin were expressed within sensory epithelia and were unaltered in Meniere's disease specimens. Expression of AQP1, AQP4, or AQP6 mRNA did not differ in vestibular endorgans from patients with Meniere's disease. Changes in AQP4 (decreased) and AQP6 (increased) expression in Meniere's disease specimens suggest that the supporting cell might be a cellular target.

  18. Pregnancy-induced up-regulation of aquaporin-4 protein in brain and its role in eclampsia.

    PubMed

    Quick, Allison M; Cipolla, Marilyn J

    2005-02-01

    Neurologic complications of eclampsia are thought to be similar to hypertensive encephalopathy in which an acute, excessive elevation in blood pressure causes blood-brain barrier (BBB) disruption and edema formation. Because women who develop eclampsia are in general normotensive and asymptomatic prior to pregnancy, we hypothesized that pregnancy alone predisposes the brain to edema formation by up-regulation of aquaporin 4 (AQP4), a water channel in the brain that has been shown to positively correlate with edema formation. To test this hypothesis, we compared localization (immunohistochemistry), mRNA (RT-PCR), and protein levels (Western analysis) of AQP4 in brains from Sprague Dawley rats that were nonpregnant (NP, proestrous), mid-pregnant (MP, days 9-10), late-pregnant (LP, days 19-20), and postpartum (PP, days 3-4). AQP4 mRNA was detected in the brains of all the animals and was localized primarily around the brain parenchymal blood vessels, strongly implicating its role in BBB function. Western analysis revealed that the major AQP4 band at approximately 32 kDa was significantly elevated in MP, LP, and PP animals compared with NP by 9-, 22-, and 17-fold, respectively. These results suggest that pregnancy and the postpartum state up-regulate AQP4 protein located around the intraparenchymal blood vessels, a consequence that could promote edema formation when blood pressure is acutely and excessively elevated, as during eclampsia.-Quick, A. M., Cipolla, M. J. Pregnancy-induced up-regulation of aquaporin-4 protein in brain and its role in eclampsia.

  19. Hypoxia-inducible factor-1alpha signaling in aquaporin upregulation after traumatic brain injury.

    PubMed

    Ding, Jamie Y; Kreipke, Christian W; Speirs, Susan L; Schafer, Patrick; Schafer, Steven; Rafols, José A

    2009-03-27

    Previous studies have demonstrated that traumatic brain injury (TBI) causes brain edema via aquaporins (AQPs), the water-transporting proteins. In the present study, we determined the role of hypoxia inducible factor-1alpha (HIF-1alpha), which is a transcription factor in response to physiological hypoxia, in regulating expression of AQP4 and AQP9. Adult male Sprague-Dawley rats (400-425g) received a closed head injury using the Marmarou weight drop model with a 450g weight and survived for 1, 4, 24 and 48h. Some animals were administered 30min after injury with 2-methoxyestradiol (2ME2), a naturally occurring metabolite of estradiol which is known to post-transcriptionally down-regulate HIF-1alpha expression, and sacrificed 4h after injury. Real-time PCR and Western blot were used, respectively, to detect gene and protein expressions of manganese superoxide dismutase (MnSOD, showing hypoxic stress), HIF-1alpha, AQP4, and AQP9. ANOVA analysis demonstrated a significant (p<0.05) increase in gene expression of MnSOD, HIF-1alpha, AQP4, and AQP9, starting at 1h after injury through 48h. Western blot analysis further indicated a significant (p<0.05) increase in protein expression of these molecules at the same time points. Pharmacological inhibition of HIF-1alpha by 2ME2 reduced the up-regulated levels of AQP4 and AQP9 after TBI. The present study suggests that hypoxic conditions determined by MnSOD expression after closed head injury contribute to HIF-1alpha expression. HIF-1alpha, in turn, up-regulates expression of AQP4 and AQP9. These results characterize the pathophysiological mechanisms, and suggest possible therapeutic targets for TBI patients.

  20. Hypoxia-Inducible Factor-1α Signaling in Aquaporin Upregulation After Traumatic Brain Injury

    PubMed Central

    Ding, Jamie Y.; Kreipke, Christian W.; Speirs, Susan L.; Schafer, Patrick; Schafer, Steven; Rafols, José A.

    2009-01-01

    Previous studies have demonstrated that traumatic brain injury (TBI) causes brain edema via aquaporins (AQPs), the water transporting proteins. In the present study, we determined the role of hypoxia inducible factor-1α (HIF-1α), which is a transcription factor in response to physiological hypoxia, in regulating expression of AQP4 and AQP9. Adult male Sprague-Dawley rats (400–425g) received a closed head injury using the Marmarou weight drop model with a 450 g weight and survived for 1, 4, 24 and 48 hours. Some animals were administered 30 minutes after injury with 2-Methoxyestradiol (2ME2), a naturally occurring metabolite of estradiol which is known to post-transcriptionally down-regulate HIF-1α expression, and sacrificed 4 hours after injury. Real-time PCR and Western blot were used, respectively, to detect gene and protein expressions of manganese superoxide dismutase (MnSOD, showing hypoxic stress), HIF-1α, AQP4, and AQP9. ANOVA analysis demonstrated a significant (p<0.05) increase in gene expression of MnSOD, HIF-1α, AQP4, and AQP9, starting at 1 hour after injury through 48 hours. Western blot analysis further indicated a significant (p<0.05) increase in protein expression of these molecules at the same time points. Pharmacological inhibition of HIF-1α by 2ME2 reduced the up-regulated levels of AQP4 and AQP9 after TBI. The present study suggests that hypoxic conditions determined by MnSOD expression after closed head injury contribute to HIF-1α expression. HIF-1α, in turn, up-regulates expression of AQP4 and AQP9. These results characterize the pathophysiological mechanisms, and suggest possible therapeutic targets for TBI patients. PMID:19429018

  1. Effect of Phenylephrine Pretreatment on the Expressions of Aquaporin 5 and c-Jun N-Terminal Kinase in Irradiated Submandibular Gland.

    PubMed

    Han, Lichi; Wang, Lei; Zhang, Fuyin; Liu, Ke Jian; Xiang, Bin

    2015-06-01

    Radiotherapy for malignant tumors of the head and neck commonly leads to radiation-induced sialadenitis as a result of radiation-induced salivary gland dysfunction. We demonstrated previously that phenylephrine could protect the irradiated submandibular gland against apoptosis, although the mechanism is unclear. In this study, we investigated the influence of phenylephrine pretreatment on the expressions of aquaporin 5 (AQP5) and c-Jun N-terminal kinase (JNK) that were presumed to have a role in radiation-induced salivary gland dysfunction. Rats pretreated with phenylephrine (5 mg/kg) were locally irradiated (20 Gy) in the head and neck region. The submandibular glands were removed on day 7 after irradiation. The expression of AQP5 and activation of JNK were measured by immunohistochemistry and Western blot. The localization of AQP5 at the apical and lateral plasma membrane of acinar cells was significantly reduced by irradiation, but markedly enhanced with phenylephrine pretreatment. The protein expression of AQP5 was decreased by 84.91% in irradiated glands, whereas it was fully recovered to the control level in phenylephrine-pretreated glands. Moreover, many acinar, ductal and granular convoluted tubular cells in the irradiated glands exhibited intense immunoreactivity for p-JNK, while in the phenylephrine-pretreated irradiated glands, only a few acinar cells exhibited very faint immunoreactivity for p-JNK. The protein expression level of p-JNK was increased by 41.65% in the irradiated alone glands, but was significantly decreased in the phenylephrine-pretreated irradiated glands. These results suggest that the protective mechanism of phenylephrine might be related to the improved expression of AQP5 and decreased activation of JNK. Pretreatment with phenylephrine in patients undergoing radiotherapy may provide a helpful strategy for suppression of radiation-induced sialadenitis.

  2. Combinations of differentiation markers distinguish subpopulations of alveolar epithelial cells in adult lung

    PubMed Central

    Marconett, Crystal N.; Juul, Nicholas; Wang, Hongjun; Liu, Yixin; Flodby, Per; Laird-Offringa, Ite A.; Minoo, Parviz

    2015-01-01

    Distal lung epithelium is maintained by proliferation of alveolar type II (AT2) cells and, for some daughter AT2 cells, transdifferentiation into alveolar type I (AT1) cells. We investigated if subpopulations of alveolar epithelial cells (AEC) exist that represent various stages in transdifferentiation from AT2 to AT1 cell phenotypes in normal adult lung and if they can be identified using combinations of cell-specific markers. Immunofluorescence microscopy showed that, in distal rat and mouse lungs, ∼20–30% of NKX2.1+ (or thyroid transcription factor 1+) cells did not colocalize with pro-surfactant protein C (pro-SP-C), a highly specific AT2 cell marker. In distal rat lung, NKX2.1+ cells coexpressed either pro-SP-C or the AT1 cell marker homeodomain only protein x (HOPX). Not all HOPX+ cells colocalize with the AT1 cell marker aquaporin 5 (AQP5), and some AQP5+ cells were NKX2.1+. HOPX was expressed earlier than AQP5 during transdifferentiation in rat AEC primary culture, with robust expression of both by day 7. We speculate that NKX2.1 and pro-SP-C colocalize in AT2 cells, NKX2.1 and HOPX or AQP5 colocalize in intermediate or transitional cells, and HOPX and AQP5 are expressed without NKX2.1 in AT1 cells. These findings suggest marked heterogeneity among cells previously identified as exclusively AT1 or AT2 cells, implying the presence of subpopulations of intermediate or transitional AEC in normal adult lung. PMID:26545903

  3. Topiramate reduced sweat secretion and aquaporin-5 expression in sweat glands of mice.

    PubMed

    Ma, Lei; Huang, Yuan-Gui; Deng, Yan-Chun; Tian, Ji-Yu; Rao, Zhi-Ren; Che, Hong-Lei; Zhang, Hai-Feng; Zhao, Gang

    2007-06-06

    Decreased sweat secretion is a primary side effect of topiramate in pediatric patients, but the mechanism underlying this effect remains unclear. This study aimed to better understand how topiramate decreases sweat secretion by examining its effect on the expression of carbonic anhydrase (CA) II and aquaporin-5 (AQP5), total CA activity, as well as on tissue morphology of sweat glands in mice. Both developing and mature mice were treated with a low (20 mg/kg/day) and high dose (80 mg/kg/day) of topiramate for 4 weeks. Sweat secretion was investigated by an established technique of examining mold impressions of hind paws. CA II and AQP5 expression levels were determined by immunofluorescence and immunoblotting and CA activity by a colorimetric assay. In mature mice, topiramate treatment decreased the number of pilocarpine reactive sweat glands from baseline in both the low and high dose groups by 83% and 75%, respectively. A similar decrease was seen in developing mice. Mature mice with reactive sweat glands that declined more than 25% compared to baseline were defined as anhidrotic mice. These mice did not differ from controls in average secretory coil diameter, CA II expression and CA activity. In contrast, anhidrotic mice did show a reduction in membrane AQP5 expression in sweat glands after topiramate delivery. Thus, sweat secretion and membrane AQP5 expression in mouse sweat glands decreased following topiramate administration. These results suggest dysregulation of AQP5 may be involved in topiramate-induced hypohidrosis and topiramate may serve as a novel therapy for hyperhidrosis.

  4. Influence of heterogeneous ammonium availability on bacterial community structure and the expression of nitrogen fixation and ammonium transporter genes during in situ bioremediation of uranium-contaminated groundwater

    SciTech Connect

    Mouser, P.J.; N'Guessan, A.L.; Elifantz, H.; Holmes, D.E.; Williams, K.H.; Wilkins, M.J.; Long, P.E.; Lovley, D.R.

    2009-04-01

    The impact of ammonium availability on microbial community structure and the physiological status and activity of Geobacter species during in situ bioremediation of uranium-contaminated groundwater was evaluated. Ammonium concentrations varied by as much as two orders of magnitude (<4 to 400 {micro}M) across the study site. Analysis of 16S rRNA gene sequences suggested that ammonium influenced the composition of the microbial community prior to acetate addition with Rhodoferax species predominating over Geobacter species at the site with the highest ammonium, and Dechloromonas species dominating at sites with lowest ammonium. However, once acetate was added, and dissimilatory metal reduction was stimulated, Geobacter species became the predominant organisms at all locations. Rates of U(VI) reduction appeared to be more related to the concentration of acetate that was delivered to each location rather than the amount of ammonium available in the groundwater. In situ mRNA transcript abundance of the nitrogen fixation gene, nifD, and the ammonium importer gene, amtB, in Geobacter species indicated that ammonium was the primary source of nitrogen during in situ uranium reduction, and that the abundance of amtB transcripts was inversely correlated to ammonium levels across all sites examined. These results suggest that nifD and amtB expression by subsurface Geobacter species are closely regulated in response to ammonium availability to ensure an adequate supply of nitrogen while conserving cell resources. Thus, quantifying nifD and amtB expression appears to be a useful approach for monitoring the nitrogen-related physiological status of Geobacter species in subsurface environments during bioremediation. This study also emphasizes the need for more detailed analysis of geochemical/physiological interactions at the field scale, in order to adequately model subsurface microbial processes.

  5. MOG cell-based assay detects non-MS patients with inflammatory neurologic disease

    PubMed Central

    Woodhall, Mark; O'Connor, Kevin C.; Reindl, Markus; Lang, Bethan; Sato, Douglas K.; Juryńczyk, Maciej; Tackley, George; Rocha, Joao; Takahashi, Toshiyuki; Misu, Tatsuro; Nakashima, Ichiro; Palace, Jacqueline; Fujihara, Kazuo; Leite, M. Isabel; Vincent, Angela

    2015-01-01

    Objective: To optimize sensitivity and disease specificity of a myelin oligodendrocyte glycoprotein (MOG) antibody assay. Methods: Consecutive sera (n = 1,109) sent for aquaporin-4 (AQP4) antibody testing were screened for MOG antibodies (Abs) by cell-based assays using either full-length human MOG (FL-MOG) or the short-length form (SL-MOG). The Abs were initially detected by Alexa Fluor goat anti-human IgG (H + L) and subsequently by Alexa Fluor mouse antibodies to human IgG1. Results: When tested at 1:20 dilution, 40/1,109 sera were positive for AQP4-Abs, 21 for SL-MOG, and 180 for FL-MOG. Only one of the 40 AQP4-Ab–positive sera was positive for SL-MOG-Abs, but 10 (25%) were positive for FL-MOG-Abs (p = 0.0069). Of equal concern, 48% (42/88) of sera from controls (patients with epilepsy) were positive by FL-MOG assay. However, using an IgG1-specific secondary antibody, only 65/1,109 (5.8%) sera were positive on FL-MOG, and AQP4-Ab– positive and control sera were negative. IgM reactivity accounted for the remaining anti-human IgG (H + L) positivity toward FL-MOG. The clinical diagnoses were obtained in 33 FL-MOG–positive patients, blinded to the antibody data. IgG1-Abs to FL-MOG were associated with optic neuritis (n = 11), AQP4-seronegative neuromyelitis optica spectrum disorder (n = 4), and acute disseminated encephalomyelitis (n = 1). All 7 patients with probable multiple sclerosis (MS) were MOG-IgG1 negative. Conclusions: The limited disease specificity of FL-MOG-Abs identified using Alexa Fluor goat anti-human IgG (H + L) is due in part to detection of IgM-Abs. Use of the FL-MOG and restricting to IgG1-Abs substantially improves specificity for non-MS demyelinating diseases. Classification of evidence: This study provides Class II evidence that the presence of serum IgG1- MOG-Abs in AQP4-Ab–negative patients distinguishes non-MS CNS demyelinating disorders from MS (sensitivity 24%, 95% confidence interval [CI] 9%–45%; specificity 100%, 95% CI 88%

  6. Distinct brain imaging characteristics of autoantibody-mediated CNS conditions and multiple sclerosis.

    PubMed

    Jurynczyk, Maciej; Geraldes, Ruth; Probert, Fay; Woodhall, Mark R; Waters, Patrick; Tackley, George; DeLuca, Gabriele; Chandratre, Saleel; Leite, Maria I; Vincent, Angela; Palace, Jacqueline

    2017-03-01

    Brain imaging characteristics of MOG antibody disease are largely unknown and it is unclear whether they differ from those of multiple sclerosis and AQP4 antibody disease. The aim of this study was to identify brain imaging discriminators between those three inflammatory central nervous system diseases in adults and children to support diagnostic decisions, drive antibody testing and generate disease mechanism hypotheses. Clinical brain scans of 83 patients with brain lesions (67 in the training and 16 in the validation cohort, 65 adults and 18 children) with MOG antibody (n = 26), AQP4 antibody disease (n = 26) and multiple sclerosis (n = 31) recruited from Oxford neuromyelitis optica and multiple sclerosis clinical services were retrospectively and anonymously scored on a set of 29 predefined magnetic resonance imaging features by two independent raters. Principal component analysis was used to perform an overview of patients without a priori knowledge of the diagnosis. Orthogonal partial least squares discriminant analysis was used to build models separating diagnostic groups and identify best classifiers, which were then tested on an independent cohort set. Adults and children with MOG antibody disease frequently had fluffy brainstem lesions, often located in pons and/or adjacent to fourth ventricle. Children across all conditions showed more frequent bilateral, large, brainstem and deep grey matter lesions. MOG antibody disease spontaneously separated from multiple sclerosis but overlapped with AQP4 antibody disease. Multiple sclerosis was discriminated from MOG antibody disease and from AQP4 antibody disease with high predictive values, while MOG antibody disease could not be accurately discriminated from AQP4 antibody disease. Best classifiers between MOG antibody disease and multiple sclerosis were similar in adults and children, and included ovoid lesions adjacent to the body of lateral ventricles, Dawson's fingers, T1 hypointense lesions (multiple

  7. Regulation of the hyperosmotic induction of aquaporin 5 and VEGF in retinal pigment epithelial cells: Involvement of NFAT5

    PubMed Central

    Vogler, Stefanie; Reichenbach, Andreas; Wiedemann, Peter; Bringmann, Andreas; Kohen, Leon

    2015-01-01

    Purpose High intake of dietary salt increases extracellular osmolarity, which results in hypertension, a risk factor of neovascular age-related macular degeneration. Neovascular retinal diseases are associated with edema. Various factors and channels, including vascular endothelial growth factor (VEGF) and aquaporins (AQPs), influence neovascularization and the development of edema. Therefore, we determined whether extracellular hyperosmolarity alters the expression of VEGF and AQPs in cultured human retinal pigment epithelial (RPE) cells. Methods Human RPE cells obtained within 48 h of donor death were prepared and cultured. Hyperosmolarity was induced by the addition of 100 mM NaCl or sucrose to the culture medium. Alterations in gene expression and protein secretion were determined with real-time RT–PCR and ELISA, respectively. The levels of signaling proteins and nuclear factor of activated T cell 5 (NFAT5) were determined by western blotting. DNA binding of NFAT5 was determined with EMSA. NFAT5 was knocked down with siRNA. Results Extracellular hyperosmolarity stimulated VEGF gene transcription and the secretion of VEGF protein. Hyperosmolarity also increased the gene expression of AQP5 and AQP8, induced the phosphorylation of p38 MAPK and ERK1/2, increased the expression of HIF-1α and NFAT5, and induced the DNA binding of NFAT5. The hyperosmotic expression of VEGF was dependent on the activation of p38 MAPK, ERK1/2, JNK, PI3K, HIF-1, and NFAT5. The hyperosmotic induction of AQP5 was in part dependent on the activation of p38 MAPK, ERK1/2, NF-κB, and NFAT5. Triamcinolone acetonide inhibited the hyperosmotic expression of VEGF but not AQP5. The expression of AQP5 was decreased by hypoosmolarity, serum, and hypoxia. Conclusions Hyperosmolarity induces the gene transcription of AQP5, AQP8, and VEGF, as well as the secretion of VEGF from RPE cells. The data suggest that high salt intake resulting in osmotic stress may aggravate neovascular retinal diseases and

  8. Cytokines and chemokines in neuromyelitis optica: pathogenetic and therapeutic implications.

    PubMed

    Uzawa, Akiyuki; Mori, Masahiro; Masahiro, Mori; Kuwabara, Satoshi

    2014-01-01

    Neuromyelitis optica (NMO) is characterized by severe optic neuritis and longitudinally extensive transverse myelitis. The discovery of an NMO-specific autoantibody to the aquaporin-4 (AQP4) water channel has improved knowledge of NMO pathogenesis. Many studies have focused on inflammatory and pathological biomarkers of NMO, including cytokines and chemokines. Increased concentrations of T helper (Th)17- and Th2-related cytokines and chemokines may be essential factors for developing NMO inflammatory lesions. For example, interleukin-6 could play important roles in NMO pathogenesis, as it is involved in the survival of plasmablasts that produce anti-AQP4 antibody in peripheral circulation and in the enhancement of inflammation in the central nervous system. Therefore, assessment of these useful biomarkers may become a supportive criterion for diagnosing NMO. Significant advances in the understanding of NMO pathogenesis will lead to the development of novel treatment strategies. This review focuses on the current advances in NMO immunological research, particularly that of cytokines and chemokines.

  9. Syndrome of inappropriate antidiuretic hormone secretion associated with seronegative neuromyelitis optica spectrum disorder

    PubMed Central

    Oh, Shin Ju; Ihm, Chun Gyoo; Lee, Tae Won; Kim, Jin Sug; Kim, Da Rae; Park, Eun Ji; Jung, Su Woong; Lee, Ji-Hoon; Heo, Sung Hyuk; Jeong, Kyung Hwan

    2017-01-01

    The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a potential cause of hyponatremia of the central nervous system (CNS). Although SIADH has been reported to be associated with many other central nervous disorders, its association with neuromyelitis optica (NMO) or NMO spectrum disorders are rare. NMO is a demyelinating disorder characterized by optic neuritis and transverse myelitis. Aquaporin-4 (AQP4), which is the target antigen for a NMO autoantibody, is the predominant CNS water channel. However, some NMO patients show seronegative AQP4 antibody results. The spectrum of NMO has been changed, and new findings about the disease have been reported. Here, we report a case of seronegative NMO spectrum disorder associated with SIADH. PMID:28393003

  10. Pretreatment with a novel aquaporin 4 inhibitor, TGN-020, significantly reduces ischemic cerebral edema.

    PubMed

    Igarashi, Hironaka; Huber, Vincent J; Tsujita, Mika; Nakada, Tsutomu

    2011-02-01

    We investigated the in vivo effects of a novel aquaporin 4 (AQP4) inhibitor 2-(nicotinamide)-1,3,4-thiadiazole, TGN-020, in a mouse model of focal cerebral ischemia using 7.0-T magnetic resonance imaging (MRI). Pretreatment with TGN-020 significantly reduced brain edema associated with brain ischemia, as reflected by percentage of brain swelling volume (%BSV), 12.1 ± 6.3% in the treated group, compared to (20.8 ± 5.9%) in the control group (p < 0.05), and in the size of cortical infarction as reflected by the percentage of hemispheric lesion volume (%HLV), 20.0 ± 7.6% in the treated group, compared to 30.0 ± 9.1% in the control group (p < 0.05). The study indicated the potential pharmacological use of AQP4 inhibition in reducing brain edema associated with focal ischemia.

  11. Insect glycerol transporters evolved by functional co-option and gene replacement

    PubMed Central

    Finn, Roderick Nigel; Chauvigné, François; Stavang, Jon Anders; Belles, Xavier; Cerdà, Joan

    2015-01-01

    Transmembrane glycerol transport is typically facilitated by aquaglyceroporins in Prokaryota and Eukaryota. In holometabolan insects however, aquaglyceroporins are absent, yet several species possess polyol permeable aquaporins. It thus remains unknown how glycerol transport evolved in the Holometabola. By combining phylogenetic and functional studies, here we show that a more efficient form of glycerol transporter related to the water-selective channel AQP4 specifically evolved and multiplied in the insect lineage, resulting in the replacement of the ancestral branch of aquaglyceroporins in holometabolan insects. To recapitulate this evolutionary process, we generate specific mutants in distantly related insect aquaporins and human AQP4 and show that a single mutation in the selectivity filter converted a water-selective channel into a glycerol transporter at the root of the crown clade of hexapod insects. Integration of phanerozoic climate models suggests that these events were associated with the emergence of complete metamorphosis and the unparalleled radiation of insects. PMID:26183829

  12. Insect glycerol transporters evolved by functional co-option and gene replacement.

    PubMed

    Finn, Roderick Nigel; Chauvigné, François; Stavang, Jon Anders; Belles, Xavier; Cerdà, Joan

    2015-07-17

    Transmembrane glycerol transport is typically facilitated by aquaglyceroporins in Prokaryota and Eukaryota. In holometabolan insects however, aquaglyceroporins are absent, yet several species possess polyol permeable aquaporins. It thus remains unknown how glycerol transport evolved in the Holometabola. By combining phylogenetic and functional studies, here we show that a more efficient form of glycerol transporter related to the water-selective channel AQP4 specifically evolved and multiplied in the insect lineage, resulting in the replacement of the ancestral branch of aquaglyceroporins in holometabolan insects. To recapitulate this evolutionary process, we generate specific mutants in distantly related insect aquaporins and human AQP4 and show that a single mutation in the selectivity filter converted a water-selective channel into a glycerol transporter at the root of the crown clade of hexapod insects. Integration of phanerozoic climate models suggests that these events were associated with the emergence of complete metamorphosis and the unparalleled radiation of insects.

  13. Regional expression of aquaporin 1, 4, and 9 in the brain during pregnancy.

    PubMed

    Wiegman, Marchien J; Bullinger, Lisa V; Kohlmeyer, Meghan M; Hunter, Timothy C; Cipolla, Marilyn J

    2008-05-01

    Pregnancy is a state of physiologic adaptation, with significant changes in cardiovascular, renal, and hemodynamic systems. Aquaporins (AQPs) may play a role in facilitating these changes. While AQP expression has been assessed in several organs during pregnancy, little is known about its expression in the brain during pregnancy. Therefore, this study assesses the regional expression of AQP1, 4, and 9 during pregnancy and the postpartum period using real-time quantitative polymerase chain reaction. The authors show that AQP1, 4, and 9 are expressed in the anterior and posterior cerebrum, cerebellum, and brainstem of nonpregnant, midpregnant, late pregnant, and postpartum rats. The regional distribution pattern of AQP4 and 9 remained similar during gestation, whereas this pattern changed for AQP1. The expression levels of AQP1, 4, and 9 in the brainstem did not change with gestation, whereas changes were found in the anterior cerebrum for AQP4 and in the posterior cerebrum and cerebellum for all AQPs.

  14. How astrocyte networks may contribute to cerebral metabolite clearance

    PubMed Central

    Asgari, Mahdi; de Zélicourt, Diane; Kurtcuoglu, Vartan

    2015-01-01

    The brain possesses an intricate network of interconnected fluid pathways that are vital to the maintenance of its homeostasis. With diffusion being the main mode of solute transport in cerebral tissue, it is not clear how bulk flow through these pathways is involved in the removal of metabolites. In this computational study, we show that networks of astrocytes may contribute to the passage of solutes between tissue and paravascular spaces (PVS) by serving as low resistance pathways to bulk water flow. The astrocyte networks are connected through aquaporin-4 (AQP4) water channels with a parallel, extracellular route carrying metabolites. Inhibition of the intracellular route by deletion of AQP4 causes a reduction of bulk flow between tissue and PVS, leading to reduced metabolite clearance into the venous PVS or, as observed in animal studies, a reduction of tracer influx from arterial PVS into the brain tissue. PMID:26463008

  15. Antibodies to MOG in adults with inflammatory demyelinating disease of the CNS

    PubMed Central

    Woodhall, Mark R.; Kim, Ji-Sun; Kim, Seong-Joon; Park, Kyung Seok; Vincent, Angela; Lee, Kwang-Woo

    2015-01-01

    Objective: To evaluate the clinical relevance of myelin oligodendrocyte glycoprotein antibody (MOG-Ab) in a cohort of adults with inflammatory demyelinating disease (IDD) of the CNS. Methods: Live cell-based assays for MOG-Ab (IgG1 subset) and antibody to aquaporin-4 (AQP4-Ab) were performed in a cohort of 270 adult patients with IDD and 72 controls. Patients were first grouped by positive antibody result as MOG-Ab or AQP4-Ab, and the remainder were grouped by published diagnostic criteria. Results: Seventeen patients with IDD (6.3%) had MOG-Abs and 49 patients (18.1%) had AQP4-Abs; none had both antibodies. The MOG-Ab patients predominantly manifested with isolated symptoms of optic neuritis (83%). One-third of these patients experienced relapses, which involved only the optic nerve, and all relapsed within 1 year of disease onset. At onset, MRI in the MOG-Ab group uniquely demonstrated perineural enhancement, extending to the soft tissues around the optic nerves (33%). Although about 30% of MOG-Ab patients had brain MRI lesions, they had fewer periventricular lesions than the 26 patients with relapsing-remitting multiple sclerosis (MS); none of these lesions were ovoid or perpendicular to the ventricle. Moreover, MOG-Ab patients did not meet the diagnostic criteria for definite neuromyelitis optica (NMO) and had less spinal cord involvement than the AQP4-Ab group. Four patients (23.5%) had poor visual outcomes (<0.2) or paraplegia. Conclusions: MOG-Abs may be a disease-specific biomarker in adult patients with IDD who have a disease distinct from NMO or MS. The radiologic as well as clinical manifestations of MOG-Ab patients can be useful in their differential diagnosis. PMID:26516628

  16. Update on the diagnosis and treatment of neuromyelitis optica: recommendations of the Neuromyelitis Optica Study Group (NEMOS).

    PubMed

    Trebst, Corinna; Jarius, Sven; Berthele, Achim; Paul, Friedemann; Schippling, Sven; Wildemann, Brigitte; Borisow, Nadja; Kleiter, Ingo; Aktas, Orhan; Kümpfel, Tania

    2014-01-01

    Neuromyelitis optica (NMO, Devic's syndrome), long considered a clinical variant of multiple sclerosis, is now regarded as a distinct disease entity. Major progress has been made in the diagnosis and treatment of NMO since aquaporin-4 antibodies (AQP4-Ab; also termed NMO-IgG) were first described in 2004. In this review, the Neuromyelitis Optica Study Group (NEMOS) summarizes recently obtained knowledge on NMO and highlights new developments in its diagnosis and treatment, based on current guidelines, the published literature and expert discussion at regular NEMOS meetings. Testing of AQP4-Ab is essential and is the most important test in the diagnostic work-up of suspected NMO, and helps to distinguish NMO from other autoimmune diseases. Furthermore, AQP4-Ab testing has expanded our knowledge of the clinical presentation of NMO spectrum disorders (NMOSD). In addition, imaging techniques, particularly magnetic resonance imaging of the brain and spinal cord, are obligatory in the diagnostic workup. It is important to note that brain lesions in NMO and NMOSD are not uncommon, do not rule out the diagnosis, and show characteristic patterns. Other imaging modalities such as optical coherence tomography are proposed as useful tools in the assessment of retinal damage. Therapy of NMO should be initiated early. Azathioprine and rituximab are suggested as first-line treatments, the latter being increasingly regarded as an established therapy with long-term efficacy and an acceptable safety profile in NMO patients. Other immunosuppressive drugs, such as methotrexate, mycophenolate mofetil and mitoxantrone, are recommended as second-line treatments. Promising new therapies are emerging in the form of anti-IL6 receptor, anti-complement or anti-AQP4-Ab biologicals.

  17. Multicentre comparison of a diagnostic assay: aquaporin-4 antibodies in neuromyelitis optica

    PubMed Central

    Waters, Patrick; Reindl, Markus; Saiz, Albert; Schanda, Kathrin; Tuller, Friederike; Kral, Vlastimil; Nytrova, Petra; Sobek, Ondrej; Nielsen, Helle Hvilsted; Barington, Torben; Lillevang, Søren T; Illes, Zsolt; Rentzsch, Kristin; Berthele, Achim; Berki, Tímea; Granieri, Letizia; Bertolotto, Antonio; Giometto, Bruno; Zuliani, Luigi; Hamann, Dörte; van Pelt, E Daniëlle; Hintzen, Rogier; Höftberger, Romana; Costa, Carme; Comabella, Manuel; Montalban, Xavier; Tintoré, Mar; Siva, Aksel; Altintas, Ayse; Deniz, Günnur; Woodhall, Mark; Palace, Jacqueline; Paul, Friedemann; Hartung, Hans-Peter; Aktas, Orhan; Jarius, Sven; Wildemann, Brigitte; Vedeler, Christian; Ruiz, Anne; Leite, M Isabel; Trillenberg, Peter; Probst, Monika; Saschenbrecker, Sandra; Vincent, Angela; Marignier, Romain

    2016-01-01

    Objective Antibodies to cell surface central nervous system proteins help to diagnose conditions which often respond to immunotherapies. The assessment of antibody assays needs to reflect their clinical utility. We report the results of a multicentre study of aquaporin (AQP) 4 antibody (AQP4-Ab) assays in neuromyelitis optica spectrum disorders (NMOSD). Methods Coded samples from patients with neuromyelitis optica (NMO) or NMOSD (101) and controls (92) were tested at 15 European diagnostic centres using 21 assays including live (n=3) or fixed cell-based assays (n=10), flow cytometry (n=4), immunohistochemistry (n=3) and ELISA (n=1). Results Results of tests on 92 controls identified 12assays as highly specific (0–1 false-positive results). 32 samples from 50 (64%) NMO sera and 34 from 51 (67%) NMOSD sera were positive on at least two of the 12 highly specific assays, leaving 35 patients with seronegative NMO/spectrum disorder (SD). On the basis of a combination of clinical phenotype and the highly specific assays, 66 AQP4-Ab seropositive samples were used to establish the sensitivities (51.5–100%) of all 21 assays. The specificities (85.8–100%) were based on 92 control samples and 35 seronegative NMO/SD patient samples. Conclusions The cell-based assays were most sensitive and specific overall, but immunohistochemistry or flow cytometry could be equally accurate in specialist centres. Since patients with AQP4-Ab negative NMO/SD require different management, the use of both appropriate control samples and defined seronegative NMOSD samples is essential to evaluate these assays in a clinically meaningful way. The process described here can be applied to the evaluation of other antibody assays in the newly evolving field of autoimmune neurology. PMID:27113605

  18. Neutrophil recruitment is critical for 5-fluorouracil-induced diarrhea and the decrease in aquaporins in the colon.

    PubMed

    Sakai, Hiroyasu; Sagara, Atsunobu; Matsumoto, Kenjiro; Jo, Ara; Hirosaki, Akiko; Takase, Kazuhide; Sugiyama, Ryoto; Sato, Ken; Ikegami, Daigo; Horie, Syunji; Matoba, Motohiro; Narita, Minoru

    2014-09-01

    Diarrhea is a common side effect experienced by cancer patients undergoing clinical chemotherapy, such as with 5-fluorouracil (5-FU). However, the precise mechanisms underlying 5-FU-induced diarrhea remain unclear. In the present study, we examined the role of neutrophil in 5-FU-induced diarrhea. Mice were given 5-FU (50mg/kg, i.p.) daily for 4 days. Sivelestat sodium (100 or 300 mg/kg, i.p., neutorophil elastase inhibitor) or SB225002 (3 or 9 mg/kg, i.p., CXCR2 antagonist) was administered before the administration of 5-FU. Gene expression levels of aquaporin (AQP) 4 and 8, CXCL1, CXCL2, CXCL3, neutrophil elastase (Elane) and myeloperoxidase (MPO) in the colon were examined by real-time RT-PCR. The neutrophil (Ly-6G positive cell) number in the mucosa of colon was measured by flow-cytometric analysis. Administration of 5-FU induced diarrhea and decreased the expression levels of AQP 4 and 8 in the colon. Under the present conditions, the expression levels of CXCL1, CXCL2, CXCL3, the neutrophil markers Elane and MPO, as well as Ly-6G-positive neutrophils, in the colon were significantly increased by 5-FU. Neutrophil recruitment with decreased levels of AQP 4 and 8 were dramatically inhibited by either sivelestat sodium or SB225002. Furthermore, these reagents reduced the 5-FU-induced body weight loss and diarrhea. These findings provide evidence that neutrophil recruitment and neutrophil elastase may decrease the levels of AQP 4 and 8 in the colon of mice treated with 5-FU and contribute to the pathophysiology of 5-FU-induced body weight loss and diarrhea.

  19. Reciprocity in the developmental regulation of aquaporins 1, 3 and 5 during pregnancy and lactation in the rat.

    PubMed

    Nazemi, Sasan; Rahbek, Mette; Parhamifar, Ladan; Moghimi, Seyed Moein; Babamoradi, Hamid; Mehrdana, Foojan; Klærke, Dan Arne; Knight, Christopher H

    2014-01-01

    Milk secretion involves significant flux of water, driven largely by synthesis of lactose within the Golgi apparatus. It has not been determined whether this flux is simply a passive consequence of the osmotic potential between cytosol and Golgi, or whether it involves regulated flow. Aquaporins (AQPs) are membrane water channels that regulate water flux. AQP1, AQP3 and AQP5 have previously been detected in mammary tissue, but evidence of developmental regulation (altered expression according to the developmental and physiological state of the mammary gland) is lacking and their cellular/subcellular location is not well understood. In this paper we present evidence of developmental regulation of all three of these AQPs. Further, there was evidence of reciprocity since expression of the rather abundant AQP3 and less abundant AQP1 increased significantly from pregnancy into lactation, whereas expression of the least abundant AQP5 decreased. It would be tempting to suggest that AQP3 and AQP1 are involved in the secretion of water into milk. Paradoxically, however, it was AQP5 that demonstrated most evidence of expression located at the apical (secretory) membrane. The possibility is discussed that AQP5 is synthesized during pregnancy as a stable protein that functions to regulate water secretion during lactation. AQP3 was identified primarily at the basal and lateral membranes of the secretory cells, suggesting a possible involvement in regulated uptake of water and glycerol. AQP1 was identified primarily at the capillary and secretory cell cytoplasmic level and may again be more concerned with uptake and hence milk synthesis, rather than secretion. The fact that expression was developmentally regulated supports, but does not prove, a regulatory involvement of AQPs in water flux through the milk secretory cell.

  20. Salivary gland development: its mediation by a subtilisin-like proprotein convertase, PACE4.

    PubMed

    Akamatsu, Tetsuya; Azlina, Ahmad; Javkhlan, Purevjav; Hasegawa, Takahiro; Yao, Chenjuan; Hosoi, Kazuo

    2009-01-01

    The submandibular gland (SMG) develops under the epithelial-mesenchymal interaction. Its process is regulated by various growth/differentiation factors, which are synthesized as inactive precursors and activated via the limited proteolysis at their multi basic amino acid site(s) such as Arg-X-Lys/Arg-Arg. Although many of these processing steps are elucidated to be catalyzed by subtilisin-like proprotein convertases (SPCs), little is known about the role of SPCs in the SMG development. Here, we focused upon the physiological role of PACE4 (SPC4), a member of SPC family, in the SMG development. In the organ culture system of rat embryonic SMG (E15), Dec-RVKR-CMK, a potent inhibitor for SPCs, inhibited the salivary branching and the expression of an exocrine gland type water channel, AQP5. However, other peptidyl-CMKs and inhibitors for trypsin-like serine proteases including leupeptin did not affect the salivary branching and AQP5 expression. Dec-RVKR-CMK also suppressed the expression of PACE4, but not furin, another member of the family. The specific antibody for the catalytic domain of PACE4 suppressed the salivary branching and AQP5 expression similarly. These inhibitory effects of Dec-RVKR-CMK were partially rescued by the addition of recombinant BMP2 whose precursor is a candidate for the physiological substrates of PACE4. Further, the transcriptional silencing of PACE4 by its specific siRNAs caused the suppression of both the salivary branching and AQP5 expression in the present organ culture system. These observations strongly support the idea that PACE4 mediates the SMG development.

  1. N-Butylphthalide Alleviates Blood–Brain Barrier Impairment in Rats Exposed to Carbon Monoxide

    PubMed Central

    Bi, Mingjun; Zhang, Mingwei; Guo, Dadong; Bi, Weikang; Liu, Bin; Zou, Yong; Li, Qin

    2016-01-01

    Carbon monoxide (CO) poisoning is one of the most important health concerns and may result in neuropathologic changes and neurologic sequelae. However, few studies have addressed the correlation between CO poisoning and blood–brain barrier (BBB) impairment. In this study, we investigated the effects of N-butylphthalide (NBP) on the expressions of zonula occludens-1 (ZO-1), claudin-5 and aquaporin-4 (AQP-4) proteins in a CO poisoning rat model. The results indicated that the brain water content was obviously increased, and the tight junctions between endothelial cells were disrupted, resulting in significant cerebral edema and BBB dysfunction in a rat model of CO poisoning. Meanwhile, the ultrastructure of endothelial cells and pericytes was seriously damaged, and the expressions of ZO-1 and claudin-5 were decreased at an early stage (<7 days). NBP treatment could efficiently maintain the ultrastructural and functional integrity of BBB, alleviate cerebral edema. Besides, NBP could also markedly increase the levels of both ZO-1 and claudin-5 proteins compared with those in rats exposed to CO (P < 0.05), whereas NBP had no apparent regulatory effect on AQP-4 expression. Taken together, this study highlights the importance of ZO-1 and claudin-5 proteins in maintaining BBB ultrastructure and function after CO poisoning. NBP, as a novel treatment approach, may effectively inhibit the down-regulation of ZO-1 and claudin-5 proteins (but not AQP-4), thereby preserving the barrier function and reducing cerebral edema after CO poisoning. PMID:27833554

  2. Occurrence of Asymptomatic Acute Neuromyelitis Optica Spectrum Disorder-Typical Brain Lesions during an Attack of Optic Neuritis or Myelitis

    PubMed Central

    Kim, Su-Hyun; Hyun, Jae-Won; Joung, AeRan; Lee, Sang Hyun; Kim, Ho Jin

    2016-01-01

    We aimed to investigate the frequency of asymptomatic acute brain MRI abnormalities accompanying optic neuritis (ON) or myelitis in neuromyelitis optica spectrum disorder (NMOSD) patients with aquaporin-4 antibodies (AQP4-Ab). We reviewed 324 brain MRI scans that were obtained during acute attacks of ON or myelitis, in 165 NMOSD patients with AQP4-Ab. We observed that acute asymptomatic NMOSD-typical brain lesions accompanied 27 (8%) acute attacks of ON or myelitis in 24 (15%) patients. The most common asymptomatic brain abnormalities included edematous corpus callosum lesions (n = 17), followed by lesions on the internal capsule and/or cerebral peduncle lesions (n = 9), periependymal surfaces of the fourth ventricle (n = 5), large deep white matter lesions (n = 4), periependymal cerebral lesions surrounding the lateral ventricles (n = 3), and hypothalamic lesions (n = 1). If asymptomatic NMOSD-typical brain abnormalities were considered as evidence for DIS, while also assuming that the AQP4-IgG status was unknown, the median time to diagnosis using the 2015 diagnosis criteria for NMOSD was shortened from 28 months to 6 months (p = 0.008). Asymptomatic acute NMOSD-typical brain lesions can be accompanied by an acute attack of ON or myelitis. Identifying these asymptomatic brain lesions may help facilitate earlier diagnosis of NMOSD. PMID:27936193

  3. The Immunology of Neuromyelitis Optica-Current Knowledge, Clinical Implications, Controversies and Future Perspectives.

    PubMed

    Jasiak-Zatonska, Michalina; Kalinowska-Lyszczarz, Alicja; Michalak, Slawomir; Kozubski, Wojciech

    2016-03-02

    Neuromyelitis optica (NMO) is an autoimmune, demyelinating disorder of the central nervous system (CNS) with typical clinical manifestations of optic neuritis and acute transverse myelitis attacks. Previously believed to be a variant of multiple sclerosis (MS), it is now considered an independent disorder which needs to be differentiated from MS. The discovery of autoantibodies against aquaporin-4 (AQP4-IgGs) changed our understanding of NMO immunopathogenesis and revolutionized the diagnostic process. AQP4-IgG is currently regarded as a specific biomarker of NMO and NMO spectrum disorders (NMOsd) and a key factor in its pathogenesis. Nevertheless, AQP4-IgG seronegativity in 10%-25% of NMO patients suggests that there are several other factors involved in NMO immunopathogenesis, i.e., autoantibodies against aquaporin-1 (AQP1-Abs) and antibodies against myelin oligodendrocyte glycoprotein (MOG-IgGs). This manuscript reviews current knowledge about NMO immunopathogenesis, pointing out the controversial issues and showing potential directions for future research. Further efforts should be made to broaden our knowledge of NMO immunology which could have important implications for clinical practice, including the use of potential novel biomarkers to facilitate an early and accurate diagnosis, and modern treatment strategies improving long-term outcome of NMO patients.

  4. Biomarkers for neuromyelitis optica.

    PubMed

    Chang, Kuo-Hsuan; Ro, Long-Sun; Lyu, Rong-Kuo; Chen, Chiung-Mei

    2015-02-02

    Neuromyelitis optica (NMO) is an acquired, heterogeneous inflammatory disorder, which is characterized by recurrent optic neuritis and longitudinally extensive spinal cord lesions. The discovery of the serum autoantibody marker, anti-aquaporin 4 (anti-AQP4) antibody, revolutionizes our understanding of pathogenesis of NMO. In addition to anti-AQP4 antibody, other biomarkers for NMO are also reported. These candidate biomarkers are particularly involved in T helper (Th)17 and astrocytic damages, which play a critical role in the development of NMO lesions. Among them, IL-6 in the peripheral blood is associated with anti-AQP4 antibody production. Glial fibrillary acidic protein (GFAP) in CSF demonstrates good correlations with clinical severity of NMO relapses. Detecting these useful biomarkers may be useful in the diagnosis and evaluation of disease activity of NMO. Development of compounds targeting these biomarkers may provide novel therapeutic strategies for NMO. This article will review the related biomarker studies in NMO and discuss the potential therapeutics targeting these biomarkers.

  5. Autoantibody to MOG suggests two distinct clinical subtypes of NMOSD

    PubMed Central

    Yan, Yaping; Li, Yujing; Fu, Ying; Yang, Li; Su, Lei; Shi, Kaibin; Li, Minshu; Liu, Qiang; Borazanci, Aimee; Liu, Yaou; He, Yong; Bennett, Jeffrey L.; Vollmer, Timothy L.; Shi, Fu-Dong

    2016-01-01

    We characterized a unique group of patients with neuromyelitis optica spectrum disorder (NMOSD) who carried autoantibodies of aquaporin-4 (AQP4) and myelin-oligodendrocyte glycoprotein (MOG). Among the 125 NMOSD patients, 10 (8.0%) were AQP4- and MOG-ab double positive, and 14 (11.2%) were MOG-ab single positive. The double-positive patients had a multiphase disease course with a high annual relapse rate (P=0.0431), and severe residual disability (P<0.0001). Of the double-positive patients, 70% had MS-like brain lesions, more severe edematous, multifocal regions on spinal magnetic resonance imaging (MRI), pronounced decreases of retinal nerve fiber layer thickness and atrophy of optic nerves. In contrast, patients with only MOG-ab had a higher ratio of monophasic disease course and mild residual disability. Spinal cord MRI illustrated multifocal cord lesions with mild edema, and brain MRIs showed more lesions around lateral ventricles. NMOSD patients carrying both autoantibodies to AQP4 and MOG existed and exhibited combined features of prototypic NMO and relapsing-remitting form of MS, whereas NMOSD with antibodies to MOG only exhibited an “intermediate” phenotype between NMOSD and MS. Our study suggests that antibodies against MOG might be pathogenic in NMOSD patients and that determination of anti-MOG antibodies maybe instructive for management of NMOSD patients. PMID:26920678

  6. Identification of a point mutation impairing the binding between aquaporin-4 and neuromyelitis optica autoantibodies.

    PubMed

    Pisani, Francesco; Mola, Maria Grazia; Simone, Laura; Rosito, Stefania; Alberga, Domenico; Mangiatordi, Giuseppe Felice; Lattanzi, Gianluca; Nicolotti, Orazio; Frigeri, Antonio; Svelto, Maria; Nicchia, Grazia Paola

    2014-10-31

    Neuromyelitis optica (NMO) is characterized by the presence of pathogenic autoantibodies (NMO-IgGs) against supra-molecular assemblies of aquaporin-4 (AQP4), known as orthogonal array of particles (OAPs). NMO-IgGs have a polyclonal origin and recognize different conformational epitopes involving extracellular AQP4 loops A, C, and E. Here we hypothesize a pivotal role for AQP4 transmembrane regions (TMs) in epitope assembly. On the basis of multialignment analysis, mutagenesis, NMO-IgG binding, and cytotoxicity assay, we have disclosed the key role of aspartate 69 (Asp(69)) of TM2 for NMO-IgG epitope assembly. Mutation of Asp(69) to histidine severely impairs NMO-IgG binding for 85.7% of the NMO patient sera analyzed here. Although Blue Native-PAGE, total internal reflection fluorescence microscopy, and water transport assays indicate that the OAP Asp(69) mutant is similar in structure and function to the wild type, molecular dynamic simulations have revealed that the D(69)H mutation has the effect of altering the structural rearrangements of extracellular loop A. In conclusion, Asp(69) is crucial for the spatial control of loop A, the particular molecular conformation of which enables the assembly of NMO-IgG epitopes. These findings provide additional clues for new strategies for NMO treatment and a wealth of information to better approach NMO pathogenesis.

  7. Identification of a Point Mutation Impairing the Binding between Aquaporin-4 and Neuromyelitis Optica Autoantibodies*

    PubMed Central

    Pisani, Francesco; Mola, Maria Grazia; Simone, Laura; Rosito, Stefania; Alberga, Domenico; Mangiatordi, Giuseppe Felice; Lattanzi, Gianluca; Nicolotti, Orazio; Frigeri, Antonio; Svelto, Maria; Nicchia, Grazia Paola

    2014-01-01

    Neuromyelitis optica (NMO) is characterized by the presence of pathogenic autoantibodies (NMO-IgGs) against supra-molecular assemblies of aquaporin-4 (AQP4), known as orthogonal array of particles (OAPs). NMO-IgGs have a polyclonal origin and recognize different conformational epitopes involving extracellular AQP4 loops A, C, and E. Here we hypothesize a pivotal role for AQP4 transmembrane regions (TMs) in epitope assembly. On the basis of multialignment analysis, mutagenesis, NMO-IgG binding, and cytotoxicity assay, we have disclosed the key role of aspartate 69 (Asp69) of TM2 for NMO-IgG epitope assembly. Mutation of Asp69 to histidine severely impairs NMO-IgG binding for 85.7% of the NMO patient sera analyzed here. Although Blue Native-PAGE, total internal reflection fluorescence microscopy, and water transport assays indicate that the OAP Asp69 mutant is similar in structure and function to the wild type, molecular dynamic simulations have revealed that the D69H mutation has the effect of altering the structural rearrangements of extracellular loop A. In conclusion, Asp69 is crucial for the spatial control of loop A, the particular molecular conformation of which enables the assembly of NMO-IgG epitopes. These findings provide additional clues for new strategies for NMO treatment and a wealth of information to better approach NMO pathogenesis. PMID:25239624

  8. The speed of swelling kinetics modulates cell volume regulation and calcium signaling in astrocytes: A different point of view on the role of aquaporins.

    PubMed

    Mola, Maria Grazia; Sparaneo, Angelo; Gargano, Concetta Domenica; Spray, David C; Svelto, Maria; Frigeri, Antonio; Scemes, Eliana; Nicchia, Grazia Paola

    2016-01-01

    Regulatory volume decrease (RVD) is a process by which cells restore their original volume in response to swelling. In this study, we have focused on the role played by two different Aquaporins (AQPs), Aquaporin-4 (AQP4), and Aquaporin-1 (AQP1), in triggering RVD and in mediating calcium signaling in astrocytes under hypotonic stimulus. Using biophysical techniques to measure water flux through the plasma membrane of wild-type (WT) and AQP4 knockout (KO) astrocytes and of an astrocyte cell line (DI TNC1) transfected with AQP4 or AQP1, we here show that AQP-mediated fast swelling kinetics play a key role in triggering and accelerating RVD. Using calcium imaging, we show that AQP-mediated fast swelling kinetics also significantly increases the amplitude of calcium transients inhibited by Gadolinium and Ruthenium Red, two inhibitors of the transient receptor potential vanilloid 4 (TRPV4) channels, and prevented by removing extracellular calcium. Finally, inhibition of TRPV4 or removal of extracellular calcium does not affect RVD. All together our study provides evidence that (1) AQP influenced swelling kinetics is the main trigger for RVD and in mediating calcium signaling after hypotonic stimulus together with TRPV4, and (2) calcium influx from the extracellular space and/or TRPV4 are not essential for RVD to occur in astrocytes.

  9. Occurrence of Asymptomatic Acute Neuromyelitis Optica Spectrum Disorder-Typical Brain Lesions during an Attack of Optic Neuritis or Myelitis.

    PubMed

    Kim, Su-Hyun; Hyun, Jae-Won; Joung, AeRan; Lee, Sang Hyun; Kim, Ho Jin

    2016-01-01

    We aimed to investigate the frequency of asymptomatic acute brain MRI abnormalities accompanying optic neuritis (ON) or myelitis in neuromyelitis optica spectrum disorder (NMOSD) patients with aquaporin-4 antibodies (AQP4-Ab). We reviewed 324 brain MRI scans that were obtained during acute attacks of ON or myelitis, in 165 NMOSD patients with AQP4-Ab. We observed that acute asymptomatic NMOSD-typical brain lesions accompanied 27 (8%) acute attacks of ON or myelitis in 24 (15%) patients. The most common asymptomatic brain abnormalities included edematous corpus callosum lesions (n = 17), followed by lesions on the internal capsule and/or cerebral peduncle lesions (n = 9), periependymal surfaces of the fourth ventricle (n = 5), large deep white matter lesions (n = 4), periependymal cerebral lesions surrounding the lateral ventricles (n = 3), and hypothalamic lesions (n = 1). If asymptomatic NMOSD-typical brain abnormalities were considered as evidence for DIS, while also assuming that the AQP4-IgG status was unknown, the median time to diagnosis using the 2015 diagnosis criteria for NMOSD was shortened from 28 months to 6 months (p = 0.008). Asymptomatic acute NMOSD-typical brain lesions can be accompanied by an acute attack of ON or myelitis. Identifying these asymptomatic brain lesions may help facilitate earlier diagnosis of NMOSD.

  10. Acetazolamide Mitigates Astrocyte Cellular Edema Following Mild Traumatic Brain Injury

    NASA Astrophysics Data System (ADS)

    Sturdivant, Nasya M.; Smith, Sean G.; Ali, Syed F.; Wolchok, Jeffrey C.; Balachandran, Kartik

    2016-09-01

    Non-penetrating or mild traumatic brain injury (mTBI) is commonly experienced in accidents, the battlefield and in full-contact sports. Astrocyte cellular edema is one of the major factors that leads to high morbidity post-mTBI. Various studies have reported an upregulation of aquaporin-4 (AQP4), a water channel protein, following brain injury. AZA is an antiepileptic drug that has been shown to inhibit AQP4 expression and in this study we investigate the drug as a therapeutic to mitigate the extent of mTBI induced cellular edema. We hypothesized that mTBI-mediated astrocyte dysfunction, initiated by increased intracellular volume, could be reduced when treated with AZA. We tested our hypothesis in a three-dimensional in vitro astrocyte model of mTBI. Samples were subject to no stretch (control) or one high-speed stretch (mTBI) injury. AQP4 expression was significantly increased 24 hours after mTBI. mTBI resulted in a significant increase in the cell swelling within 30 min of mTBI, which was significantly reduced in the presence of AZA. Cell death and expression of S100B was significantly reduced when AZA was added shortly before mTBI stretch. Overall, our data point to occurrence of astrocyte swelling immediately following mTBI, and AZA as a promising treatment to mitigate downstream cellular mortality.

  11. Anti-aquaporin-4 antibody-positive neuromyelitis optica presenting with syndrome of inappropriate antidiuretic hormone secretion as an initial manifestation.

    PubMed

    Nakajima, H; Fujiki, Y; Ito, T; Kitaoka, H; Takahashi, T

    2011-09-01

    The distribution of neuromyelitis optica (NMO)-characteristic brain lesions corresponds to sites of high aquaporin-4 (AQP4) expression, and the brainstem and hypothalamus lesions that express high levels of AQP4 protein are relatively characteristic of NMO. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is one of the important causes of hyponatremia and results from an abnormal production or sustained secretion of antidiuretic hormone (ADH). SIADH has been associated with many clinical states or syndromes, and the hypothalamic-neurohypophyseal system regulates the feedback control system for ADH secretion. We report the case of a 63-year-old man with NMO, whose initial manifestation was hyponatremia caused by SIADH. Retrospective analysis revealed that the serum anti-AQP4 antibody was positive, and an MRI scan showed a unilateral lesion in the hypothalamus. SIADH recovered completely with regression of the hypothalamic lesion. As such, NMO should even be considered in patients who develop SIADH and have no optic nerve or spinal cord lesions but have MRI-documented hypothalamic lesions.

  12. Combustion smoke exposure induces up-regulated expression of vascular endothelial growth factor, aquaporin 4, nitric oxide synthases and vascular permeability in the retina of adult rats.

    PubMed

    Zou, Y Y; Lu, J; Poon, D J F; Kaur, C; Cao, Q; Teo, A L; Ling, E A

    2009-05-19

    Retinal cells respond to various experimental stimuli including hypoxia, yet it remains to be investigated whether they react to smoke inhalation. We show here that retinal cells in rats, notably the ganglion cells, Müller cells, astrocytes and blood vessels responded vigorously to a smoke challenge. The major changes included up-regulated expression of vascular endothelial growth factor (VEGF), aquaporin 4 (AQP4) and nitric oxide synthase (NOS). VEGF expression was localized in the ganglion cells, Müller cells, astrocytes and associated blood vessels. AQP4 was markedly enhanced in both astrocytes and Müller cells. Increase in vascular permeability after smoke exposure was evidenced by extravasation of serum derived rhodamine isothiocyanate which was internalized by Müller cells and ganglion cells. The tracer leakage was attenuated by aminoguanidine and N(G)-nitro-L-arginine methyl ester (L-NAME) treatment which suppressed retinal tissue NOS and nitric oxide (NO) levels concomitantly. It is suggested that VEGF, AQP4 and NO are involved in increased vascular permeability following acute smoke exposure in which hypoxia was ultimately implicated as shown by blood gases analysis. NOS inhibitors effectively reduced the vascular leakage and hence may ameliorate possible retinal edema in smoke inhalation.

  13. Human Aquaporin-4 and Molecular Modeling: Historical Perspective and View to the Future

    PubMed Central

    Mangiatordi, Giuseppe Felice; Alberga, Domenico; Trisciuzzi, Daniela; Lattanzi, Gianluca; Nicolotti, Orazio

    2016-01-01

    Among the different aquaporins (AQPs), human aquaporin-4 (hAQP4) has attracted the greatest interest in recent years as a new promising therapeutic target. Such a membrane protein is, in fact, involved in a multiple sclerosis-like immunopathology called Neuromyelitis Optica (NMO) and in several disorders resulting from imbalanced water homeostasis such as deafness and cerebral edema. The gap of knowledge in its functioning and dynamics at the atomistic level of detail has hindered the development of rational strategies for designing hAQP4 modulators. The application, lately, of molecular modeling has proved able to fill this gap providing a breeding ground to rationally address compounds targeting hAQP4. In this review, we give an overview of the important advances obtained in this field through the application of Molecular Dynamics (MD) and other complementary modeling techniques. The case studies presented herein are discussed with the aim of providing important clues for computational chemists and biophysicists interested in this field and looking for new challenges. PMID:27420052

  14. Virchow-Robin space and aquaporin-4: new insights on an old friend

    PubMed Central

    Nakada, Tsutomu

    2014-01-01

    Recent studies have strongly indicated that the classic circulation model of cerebrospinal fluid (CSF) is no longer valid. The production of CSF is not only dependent on the choroid plexus but also on water flux in the peri-capillary (Virchow Robin) space. Historically, CSF flow through the Virchow Robin space is known as interstitial flow, the physiological significance of which is now fully understood. This article briefly reviews the modern concept of CSF physiology and the Virchow-Robin space, in particular its functionalities critical for central nervous system neural activities. Water influx into the Virchow Robin space and, hence, interstitial flow is regulated by aquaporin-4 (AQP-4) localized in the endfeet of astrocytes, connecting the intracellular cytosolic fluid space of astrocytes and the Virchow Robin space. Interstitial flow has a functionality equivalent to systemic lymphatics, on which clearance of β-amyloid is strongly dependent. Autoregulation of brain blood flow serves to maintain a constant inner capillary fluid pressure, allowing fluid pressure of the Virchow Robin space to regulate regional cerebral blood flow (rCBF) based on AQP-4 gating. Excess heat produced by neural activities is effectively removed from the area of activation by increased rCBF by closing AQP-4 channels. This neural flow coupling (NFC) is likely mediated by heat generated proton channels. PMID:25165047

  15. Defatted sesame seed extract reduces brain oedema by regulating aquaporin 4 expression in acute phase of transient focal cerebral ischaemia in rat.

    PubMed

    Lee, Kyungjin; Jo, In-Young; Park, Si Hyung; Kim, Kwan Su; Bae, Jinhyun; Park, Jae-Woo; Lee, Beom-Joon; Choi, Ho-Young; Bu, Youngmin

    2012-10-01

    Brain oedema is the volumetric increase of brain tissue and is known to be linked to vascular factors, including the blood-brain barrier (BBB) and vascular permeability. Besides neuroprotection, inhibition of brain oedema also can be a method to protect the brain against ischaemic insult. Sesame is reported to have various beneficial effects on the cardiovascular and cerebrovascular systems. The neuroprotective effects of defatted sesame seed extract (DSE) in a transient middle cerebral artery occlusion (tMCAo) rat model were reported previously. The current study was planned to investigate whether the neuroprotective effects of DSE is related to brain oedema. The tMCAo rat model was used to investigate the brain water content (BWC) and Evans blue (EB) leakage. Aquaporin 4 (AQP4), matrix metalloproteinase (MMP)-2 and MMP-9 expressions at 4 and 24 h after ischaemia were analysed. In vitro zymography was performed to investigate the effects on MMPs activities. DSE (30, 100, and 300 mg/kg, p.o.) reduced BWC but not EB leakage. DSE inhibited AQP4 expression at 4 h but not at 24 h after ischaemia. It did not show any effects on MMPs expressions and activities. Therefore, DSE might be effective on brain oedema by AQP4 regulation during the acute phase of ischaemia.

  16. Acetazolamide Mitigates Astrocyte Cellular Edema Following Mild Traumatic Brain Injury

    PubMed Central

    Sturdivant, Nasya M.; Smith, Sean G.; Ali, Syed F.; Wolchok, Jeffrey C.; Balachandran, Kartik

    2016-01-01

    Non-penetrating or mild traumatic brain injury (mTBI) is commonly experienced in accidents, the battlefield and in full-contact sports. Astrocyte cellular edema is one of the major factors that leads to high morbidity post-mTBI. Various studies have reported an upregulation of aquaporin-4 (AQP4), a water channel protein, following brain injury. AZA is an antiepileptic drug that has been shown to inhibit AQP4 expression and in this study we investigate the drug as a therapeutic to mitigate the extent of mTBI induced cellular edema. We hypothesized that mTBI-mediated astrocyte dysfunction, initiated by increased intracellular volume, could be reduced when treated with AZA. We tested our hypothesis in a three-dimensional in vitro astrocyte model of mTBI. Samples were subject to no stretch (control) or one high-speed stretch (mTBI) injury. AQP4 expression was significantly increased 24 hours after mTBI. mTBI resulted in a significant increase in the cell swelling within 30 min of mTBI, which was significantly reduced in the presence of AZA. Cell death and expression of S100B was significantly reduced when AZA was added shortly before mTBI stretch. Overall, our data point to occurrence of astrocyte swelling immediately following mTBI, and AZA as a promising treatment to mitigate downstream cellular mortality. PMID:27623738

  17. Clustering of Kir4.1 at specialized compartments of the lateral membrane in ependymal cells of rat brain.

    PubMed

    Fujita, Akikazu; Inanobe, Atsushi; Hibino, Hiroshi; Nielsen, Søren; Ottersen, Ole Petter; Kurachi, Yoshihisa

    2015-02-01

    Brain ependymal cells, which form an epithelial layer covering the cerebral ventricles, have been shown to play a role in the regulation of cerebrospinal and interstitial fluids. The machinery underlying this, however, remains largely unknown. Here, we report the specific localization of an inwardly rectifying K(+) channel, Kir4.1, on the ependymal cell membrane suggesting involvement of the channel in this function. Immunohistochemical study with confocal microscopy identified Kir4.1 labeling on the lateral but not apical membrane of ependymal cells. Ultrastructural analysis revealed that Kir4.1-immunogold particles were specifically localized and clustered on adjacent membranes at puncta adherens type junctions, whereas an aquaporin water channel, AQP4, that was also detected on the lateral membrane only occurred at components other than adherens junctions. Therefore, in ependymal cells, Kir4.1 and AQP4 are partitioned into distinct membrane compartments that might respectively transport either K(+) or water. Kir4.1 was also expressed in a specialized form of ependymal cell, namely the tanycyte, being abundant in tanycyte processes wrapping neuropils and blood vessels. These specific localizations suggest that Kir4.1 mediates intercellular K(+) exchange between ependymal cells and also K(+)-buffering transport via tanycytes that can interconnect neurons and vessels/ventricles. We propose that ependymal cells and tanycytes differentially operate Kir4.1 and AQP4 actively to control the property of fluids at local areas in the brain.

  18. Expression of aquaporins in the cochlea and endolymphatic sac of guinea pig.

    PubMed

    Zhong, Shi-Xun; Liu, Zhao-Hua

    2003-01-01

    It has been shown that the aquaporin (AQP) family forms membrane pores selectively permeable for water and some small solutes such as glycerol and urea, and thus plays important roles in regulating the fluid in many organs involved in fluid transport such as kidney, lung and brain. The aims of the present study were to investigate the cellular localization and its significance of aquaporins (AQPs) in various subregions of the cochlea and endolymphatic sac of guinea pig. The expression patterns of AQP1, 2, 3 and 4 were immunolabeled with the specific polyclonal rabbit antibodies against the rat AQP1, 2, 3 and 4. Our immunohistochemical examination showed that in the cochlea, AQP1, 3 and 4 were widely distributed in various locations including stria vascularis, spiral ligament, the organ of Corti and spiral ganglion in the similar patterns except that AQP3 in the stria vascularis was lightly weaker than AQP1 and AQP4. AQP2 was labeled only in Reissner's membrane. In the endolymphatic sac, AQP1, AQP3 and AQP4 were strongly expressed in the epithelial cells and subepithelial cells similarly with the exception that AQP3 was lightly weaker than AQP1 and AQP4. No AQP2 immunoreactivity was detected in the endolymphatic sac. Theses results suggest that different members of the AQP family in the labyrinth may work in concert to regulate endolymph and to maintain homeostasis in the inner ear.

  19. Aquaporins are upregulated in glandular epithelium at the time of implantation in the rat.

    PubMed

    Lindsay, Laura A; Murphy, Christopher R

    2007-03-01

    Regulation of luminal fluid is essential for blastocyst implantation. While it has been known for quite some time that there is a reduction in the amount of luminal fluid at the time of implantation, the mechanisms regulating this process are only just emerging. Previous studies have shown an upregulation of aquaporin (AQP) 5 channels in luminal epithelial cells at the time of implantation providing a mechanism for fluid reabsorption across the surface epithelium. However to date the contribution of fluid reabsorption by glandular epithelial cells has not been established. This study using reverse transcriptase polymerase chain reaction demonstrates the presence of several AQP isoforms in the rat uterus at the time of implantation while immunofluorescence data demonstrates an apical distribution of AQPs5 and 9 in the glandular epithelium at the time of implantation. The presence of AQPs5 and 9 in the apical plasma membrane of the glandular epithelium seen in this study provides a mechanism for transcellular fluid transport across these glandular epithelial cells similar to that seen in luminal epithelial cells. The reabsorption of glandular fluid via AQP channels may also regulate luminal fluid volume and be involved in the reduction in luminal fluid seen at the time of implantation.

  20. Solute transport on the sub 100 ms scale across the lipid bilayer membrane of individual proteoliposomes.

    PubMed

    Ohlsson, Gabriel; Tabaei, Seyed R; Beech, Jason; Kvassman, Jan; Johanson, Urban; Kjellbom, Per; Tegenfeldt, Jonas O; Höök, Fredrik

    2012-11-21

    Screening assays designed to probe ligand and drug-candidate regulation of membrane proteins responsible for ion-translocation across the cell membrane are wide spread, while efficient means to screen membrane-protein facilitated transport of uncharged solutes are sparse. We report on a microfluidic-based system to monitor transport of uncharged solutes across the membrane of multiple (>100) individually resolved surface-immobilized liposomes. This was accomplished by rapidly switching (<10 ms) the solution above dye-containing liposomes immobilized on the floor of a microfluidic channel. With liposomes encapsulating the pH-sensitive dye carboxyfluorescein (CF), internal changes in pH induced by transport of a weak acid (acetic acid) could be measured at time scales down to 25 ms. The applicability of the set up to study biological transport reactions was demonstrated by examining the osmotic water permeability of human aquaporin (AQP5) reconstituted in proteoliposomes. In this case, the rate of osmotic-induced volume changes of individual proteoliposomes was time resolved by imaging the self quenching of encapsulated calcein in response to an osmotic gradient. Single-liposome analysis of both pure and AQP5-containing liposomes revealed a relatively large heterogeneity in osmotic permeability. Still, in the case of AQP5-containing liposomes, the single liposome data suggest that the membrane-protein incorporation efficiency depends on liposome size, with higher incorporation efficiency for larger liposomes. The benefit of low sample consumption and automated liquid handling is discussed in terms of pharmaceutical screening applications.

  1. Sialadenosis of the major salivary glands in a patient with central diabetes insipidus--implications of aquaporin water channels in the pathomechanism of sialadenosis.

    PubMed

    Mandic, R; Teymoortash, A; Kann, P H; Werner, J A

    2005-04-01

    Sialadenosis, also referred to as sialosis, is a disease of unknown aetiology. It regularly manifests itself as a massive swelling in both parotid regions involving the major salivary glands, preferably the parotid glands and is characterized by lack of any detectable, underlying pathologies. In this case report we describe a 24-year-old white female patient with diabetes insipidus who developed sialadenosis of the major salivary glands during a period of enhanced water requirement, which the patient tried to compensate for by more frequent nasal ADH application. Since ADH acts on aquaporins (AQPs) in the kidney, we were interested if AQP expression in the patients salivary glands was affected. Surprisingly, compared to normal control tissues we observed an extensively high signal for AQP5, which is the dominant AQP found in salivary acinar cells. Interestingly, previous studies on AQP5 knock out mice found AQP5 to be required for cell volume regulation. We therefore suggest that aquaporin water channels and antidiuretic hormone together with a disturbance in the body's water household are potential key-factors in the pathophysiological events leading to the development of the disease entity called sialadenosis.

  2. An Experimental Study on Botulinum Toxin Type A for the Treatment of Excessive Secretion after Submandibular Gland Transplantation in Rabbits

    PubMed Central

    Lin, Bo; Wang, Kan

    2016-01-01

    Objectives. To investigate whether botulinum toxin type A (BTXA) could control excessive secretion after submandibular gland (SMG) transplantation in rabbits and its possible mechanisms. Methods. A new SMG transplantation model was established in rabbit. 30 successfully constructed models were randomly assigned to five groups including control group and four experimental groups. Secretion outputs were used to analyze the effect of BTXA injection on excessive secretion. Hematoxylin and eosin (HE) staining, transmission electron microscopy (TEM), Western blot, and immunofluorescence were performed to analyze its possible mechanisms. Results. After BTXA injection, a significant decrease of excessive secretion after SMG transplantation was found in 2 and 4 weeks groups, but no significant effect on 12 and 24 weeks groups. HE and TEM results showed that BTXA led to morphological and ultrastructural changes of acinar cells of transplanted SMG. Western blot results suggested that BTXA decreased the aquaporin-5 (AQP5) protein expression after BTXA injection for 2 and 4 weeks. Immunofluorescence results showed that AQP5 protein was mainly expressed in the cytoplasm after BTXA injection for 2 and 4 weeks, which might indicate that BTXA promoted AQP5 expression from the cell membrane to cytoplasm. Conclusion. BTXA could effectively control excessive secretion after SMG transplantation in rabbits. PMID:27840738

  3. PACAP suppresses dry eye signs by stimulating tear secretion

    PubMed Central

    Nakamachi, Tomoya; Ohtaki, Hirokazu; Seki, Tamotsu; Yofu, Sachiko; Kagami, Nobuyuki; Hashimoto, Hitoshi; Shintani, Norihito; Baba, Akemichi; Mark, Laszlo; Lanekoff, Ingela; Kiss, Peter; Farkas, Jozsef; Reglodi, Dora; Shioda, Seiji

    2016-01-01

    Dry eye syndrome is caused by a reduction in the volume or quality of tears. Here, we show that pituitary adenylate cyclase-activating polypeptide (PACAP)-null mice develop dry eye-like symptoms such as corneal keratinization and tear reduction. PACAP immunoreactivity is co-localized with a neuronal marker, and PACAP receptor (PAC1-R) immunoreactivity is observed in mouse infraorbital lacrimal gland acinar cells. PACAP eye drops stimulate tear secretion and increase cAMP and phosphorylated (p)-protein kinase A levels in the infraorbital lacrimal glands that could be inhibited by pre-treatment with a PAC1-R antagonist or an adenylate cyclase inhibitor. Moreover, these eye drops suppress corneal keratinization in PACAP-null mice. PACAP eye drops increase aquaporin 5 (AQP5) levels in the membrane and pAQP5 levels in the infraorbital lacrimal glands. AQP5 siRNA treatment of the infraorbital lacrimal gland attenuates PACAP-induced tear secretion. Based on these results, PACAP might be clinically useful to treat dry eye disorder. PMID:27345595

  4. THE PERIVASCULAR POOL OF AQUAPORIN-4 MEDIATES THE EFFECT OF OSMOTHERAPY IN POST-ISCHEMIC CEREBRAL EDEMA

    PubMed Central

    Zeynalov, Emil; Chen, Chih-Hung; Froehner, Stanley C.; Adams, Marvin E.; Ottersen, Ole Petter; Amiry-Moghaddam, Mahmood; Bhardwaj, Anish

    2009-01-01

    Objective Osmotherapy with hypertonic saline (HS) ameliorates cerebral edema associated with experimental ischemic stroke. We tested the hypothesis that HS exerts its anti-edema effect by promoting an efflux of water from brain via the perivascular aquaporin-4 (AQP4) pool. We utilized mice with targeted disruption of the gene encoding α-syntrophin (α-Syn−/−) that lack the perivascular AQP4 pool but retain the endothelial pool of this protein. Design Prospective laboratory animal study. Setting Research laboratory in a university teaching hospital. Measurements and Main Results Halothane-anesthetized adult male wildtype (WT) C57B/6 and α-Syn−/− mice were subjected to 90 min of transient middle cerebral artery occlusion (MCAO) and treated with either a continuous intravenous infusion of 0.9% saline (NS) or 3% HS (1.5 mL/Kg/hr) for 48 hr. In the first series of experiments (n = 59), brain water content analyzed by wet-to-dry ratios in the ischemic hemisphere of WT mice was attenuated after HS (79.9 ± 0.5%mean ± SEM) but not after NS (82.3 ± 1.0%) treatment. In contrast in α-Syn−/− mice, HS had no effect on the postischemic edema (HS: 80.3 ± 0.7% NS: 80.3 ± 0.4%). In the second series of experiments (n = 31), treatment with HS attenuated post-ischemic BBB disruption at 48 hr in WT mice but not in α-Syn−/− mice; α-Syn deletion alone had no effect on BBB integrity. In the third series of experiments (n=34), α-Syn−/− mice treated with either HS or NS had smaller infarct volume as compared with their WT counterparts. Conclusions These data demonstrate that: 1) osmotherapy with HS exerts anti-edema effects via the perivascular pool of AQP4 2) HS attenuates BBB disruption depending on the presence of perivascular AQP4, and 3) deletion of the perivascular pool of AQP4 alleviates tissue damage following stroke, in mice subjected to osmotherapy as well as in non-treated mice. PMID:18679106

  5. Features of Gene Expression of Bacillus pumilus Metalloendopeptidase.

    PubMed

    Rudakova, N L; Sabirova, A R; Balaban, N P; Tikhonova, A O; Sharipova, M R

    2016-08-01

    Features of gene expression of the secreted Bacillus pumilus metalloendopeptidase belonging to the adamalysin/reprolysin family were investigated. In the regulatory region of the gene, we identified hypothetical binding sites for transcription factors CcpA and TnrA. We found that the expression of the metalloendopeptidase gene is controlled by mechanisms of carbon and nitrogen catabolite repression. In experiments involving nitrogen metabolism regulatory protein mutant strains, we found that the control of the metalloendopeptidase gene expression involves proteins of ammonium transport GlnK and AmtB interacting with the TnrA-regulator.

  6. Aquaporin deletion in mice reduces intraocular pressure and aqueous fluid production.

    PubMed

    Zhang, Duo; Vetrivel, L; Verkman, A S

    2002-06-01

    Aquaporin (AQP) water channels are expressed in the eye at sites of aqueous fluid production and outflow: AQP1 and AQP4 in nonpigmented ciliary epithelium, and AQP1 in trabecular meshwork endothelium. Novel methods were developed to compare aqueous fluid dynamics in wild-type mice versus mice lacking AQP1 and/or AQP4. Aqueous fluid production was measured by in vivo confocal microscopy after transcorneal iontophoretic introduction of fluorescein. Intraocular pressure (IOP), outflow, and anterior chamber compliance were determined from pressure measurements in response to fluid infusions using micropipettes. Aqueous fluid volume and [Cl(-)] were assayed in samples withdrawn by micropipettes. In wild-type mice (CD1 genetic background, age 4-6 wk), IOP was 16.0 +/- 0.4 mmHg (SE), aqueous fluid volume 7.2 +/- 0.3 microl, fluid production 3.6 +/- 0.2 microl/h, fluid outflow 0.36 +/- 0.06 microl/h/mmHg, and compliance 0.036 +/- 0.006 microl/mmHg. IOP was significantly decreased by up to 1.8 mmHg (P < 0.002) and fluid production by up to 0.9 microl/h in age/litter-matched mice lacking AQP1 and/or AQP4 (outbred CD1 and inbred C57/bl6 genetic backgrounds). However, AQP deletion did not significantly affect outflow, [Cl(-)], volume, or compliance. These results provide evidence for the involvement of AQPs in intraocular pressure regulation by facilitating aqueous fluid secretion across the ciliary epithelium. AQP inhibition may thus provide a novel approach for the treatment of elevated IOP.

  7. A new gating site in human aquaporin-4: Insights from molecular dynamics simulations.

    PubMed

    Alberga, Domenico; Nicolotti, Orazio; Lattanzi, Gianluca; Nicchia, Grazia Paola; Frigeri, Antonio; Pisani, Francesco; Benfenati, Valentina; Mangiatordi, Giuseppe Felice

    2014-12-01

    Aquaporin-4 (AQP4) is the predominant water channel in different organs and tissues. An alteration of its physiological functioning is responsible for several disorders of water regulation and, thus, is considered an attractive target with a promising therapeutic and diagnostic potential. Molecular dynamics (MD) simulations performed on the AQP4 tetramer embedded in a bilayer of lipid molecules allowed us to analyze the role of spontaneous fluctuations occurring inside the pore. Following the approach by Hashido et al. [Hashido M, Kidera A, Ikeguchi M (2007) Biophys J 93: 373-385], our analysis on 200ns trajectory discloses three domains inside the pore as key elements for water permeation. Herein, we describe the gating mechanism associated with the well-known selectivity filter on the extracellular side of the pore and the crucial regulation ensured by the NPA motifs (asparagine, proline, alanine). Notably, on the cytoplasmic side, we find a putative gate formed by two residues, namely, a cysteine belonging to the loop D (C178) and a histidine from loop B (H95). We observed that the spontaneous reorientation of the imidazole ring of H95 acts as a molecular switch enabling H-bond interaction with C178. The occurrence of such local interaction seems to be responsible for the narrowing of the pore and thus of a remarkable decrease in water flux rate. Our results are in agreement with recent experimental observations and may represent a promising starting point to pave the way for the discovery of chemical modulators of AQP4 water permeability.

  8. D184E mutation in aquaporin-4 gene impairs water permeability and links to deafness.

    PubMed

    Nicchia, G P; Ficarella, R; Rossi, A; Giangreco, I; Nicolotti, O; Carotti, A; Pisani, F; Estivill, X; Gasparini, P; Svelto, M; Frigeri, A

    2011-12-01

    Aquaporins (AQPs) play a physiological role in several organs and tissues, and their alteration is associated with disorders of water regulation. The identification of molecular interactions, which are crucial in determining the rate of water flux through the channel, is of pivotal role for the discovery of molecules able to target those interactions and therefore to be used for pathologies ascribable to an altered AQP-dependent water balance. In the present study, a mutational screening of human aquaporin-4 (AQP4) gene was performed on subjects with variable degrees of hearing loss. One heterozygous missense mutation was identified in a Spanish sporadic case, leading to an Asp/Glu amino acid substitution at position 184 (D184E). A BLAST analysis revealed that the amino acid D184 is conserved across species, consistently with a crucial role in the structure/function of AQP4 water channels. The mutation induces a significant reduction in water permeability as measured by the Xenopus laevis oocytes swelling assay and by the use of mammalian cells by total internal reflection microscopy. By Western blot, immunofluorescence and 2D Blue Native/SDS-PAGE we show that the reduction in water permeability is not ascribable to a reduced expression of AQP4 mutant protein or to its incorrect plasma membrane targeting and aggregation into orthogonal arrays of particles. Molecular dynamics simulation provided a molecular explanation of the mechanism whereby the mutation induces a loss of function of the channel. Substituting glutamate for aspartate affects the mobility of the D loop, which acquires a higher propensity to equilibrate in a "closed conformation", thus affecting the rate of water flux. We speculate that this mutation, combined with other genetic defects or concurrently with certain environmental stimuli, could confer a higher susceptibility to deafness.

  9. The Speed of Swelling Kinetics Modulates Cell Volume Regulation and Calcium Signaling in Astrocytes: A Different Point of View on the Role of Aquaporins

    PubMed Central

    Mola, Maria Grazia; Sparaneo, Angelo; Gargano, Concetta Domenica; Spray, David C.; Svelto, Maria; Frigeri, Antonio; Scemes, Eliana; Nicchia, Grazia Paola

    2016-01-01

    Regulatory volume decrease (RVD) is a process by which cells restore their original volume in response to swelling. In this study, we have focused on the role played by two different Aquaporins (AQPs), Aquaporin-4 (AQP4), and Aquaporin-1 (AQP1), in triggering RVD and in mediating calcium signaling in astrocytes under hypotonic stimulus. Using biophysical techniques to measure water flux through the plasma membrane of wild-type (WT) and AQP4 knockout (KO) astrocytes and of an astrocyte cell line (DI TNC1) transfected with AQP4 or AQP1, we here show that AQP-mediated fast swelling kinetics play a key role in triggering and accelerating RVD. Using calcium imaging, we show that AQP-mediated fast swelling kinetics also significantly increases the amplitude of calcium transients inhibited by Gadolinium and Ruthenium Red, two inhibitors of the transient receptor potential vanilloid 4 (TRPV4) channels, and prevented by removing extracellular calcium. Finally, inhibition of TRPV4 or removal of extracellular calcium does not affect RVD. All together our study provides evidence that (1) AQP influenced swelling kinetics is the main trigger for RVD and in mediating calcium signaling after hypotonic stimulus together with TRPV4, and (2) calcium influx from the extracellular space and/or TRPV4 are not essential for RVD to occur in astrocytes. Main Points: (1) The speed of swelling kinetics is the main trigger for Regulatory Volume Decrease (RVD) and for calcium response in astrocytes; (2) Calcium influx from the extracellular space and TRPV4 are not essential for RVD. PMID:26413835

  10. Vasopressin receptors V1a and V2 are not osmosensors

    PubMed Central

    Lykke, Kasper; Assentoft, Mette; Fenton, Robert A; Rosenkilde, Mette M; MacAulay, Nanna

    2015-01-01

    Herein, we investigated whether G protein-coupled signaling via the vasopressin receptors of the V1a and V2 subtypes (V1aR and V2R) could be obtained as a direct response to hyperosmolar challenges and/or whether hyperosmolar challenges could augment classical vasopressin-dependent V1aR signaling. The V1aR-dependent response was monitored indirectly via its effects on aquaporin 4 (AQP4) when heterologously expressed in Xenopus oocytes and V1aR and V2R function was directly monitored following heterologous expression in COS-7 cells. A tendency toward an osmotically induced, V1aR-mediated reduction in AQP4-dependent water permeability was observed, although osmotic challenges failed to mimic vasopressin-dependent V1aR-mediated internalization of AQP4. Direct monitoring of inositol phosphate (IP) production of V1aR-expressing COS-7 cells demonstrated an efficient vasopressin-dependent response that was, however, independent of hyperosmotic challenges. Similarly, the cAMP production by the V2R was unaffected by hyperosmotic challenges although, in contrast to the V1aR, the V2R displayed an ability to support alternative signaling (IP production) at higher concentration of vasopressin. V1aR and V2R respond directly to vasopressin exposure, but they do not have an ability to act as osmo- or volume sensors when exposed to an osmotic gradient in the absence or presence of vasopressin. PMID:26311834

  11. The effect of cigarette smoke exposure on spinal cord injury in rats.

    PubMed

    Fan, Zhong-kai; Cao, Yang; Lv, Gang; Wang, Yan-song; Guo, Zhan-peng

    2013-03-15

    In this study, we examined whether cigarette smoke has neuroprotective or toxic effects on spinal cord injury (SCI). Male Sprague-Dawley rats were included in the study and received either cigarette smoke exposure or fresh air exposure. Twenty-four hours after the last cigarette smoke or fresh air exposure, all rats were injured at thoracic level 12 (T12), using an established static compression model. Our data showed that the cigarette smoke group had higher water content; higher permeability of the blood-spinal cord barrier (BSCB); higher malondialdehyde (MDA) levels, aquaporin-4 (AQP4) and hypoxia-inducible factor 1-alpha (HIF-1α) protein expression, and mRNA levels; and lower glutathione (GSH) levels than the control group values at 12 h, 24 h, and 48 h after SCI. There was no significant difference in these between the cigarette smoke group and the control group at 0 h after SCI. The results of the Basso, Beattie, and Bresnahan (BBB) hindlimb locomotor rating scale showed that rats in the cigarette smoke group had greater dysfunction in hindlimb movement than did rats in control group from 2 to day 6 after SCI. The extent of recovery did not make any difference from day 7 to day 10 after SCI between the cigarette smoke group and the control group. These results suggested that cigarette smoke can reinforce the oxidative stress injury via HIF-1α and AQP4 in the early stage after SCI. It is possible that cigarette smoke exposure does not affect SCI recovery in the long term; however, it can aggravate the edema and deteriorate BSCB disruption via HIF-1α and AQP4 in the early stage after SCI. More studies will be essential to consider this hypothesis and elucidate the mechanisms involved.

  12. Resveratrol ameliorates oxidative stress and inhibits aquaporin 4 expression following rat cerebral ischemia-reperfusion injury.

    PubMed

    Li, Weina; Tan, Changhong; Liu, Yi; Liu, Xi; Wang, Xin; Gui, Yuejiang; Qin, Lu; Deng, Fen; Yu, Zhen; Hu, Changlin; Chen, Lifen

    2015-11-01

    Cerebral ischemia-reperfusion (I/R) is associated with increased levels of reactive oxygen species (ROS) and brain edema, which lead to the deterioration of patient prognosis. Resveratrol serves a neuroprotective role in I/R injury, and this role may be associated with its anti‑oxidative effects. However, resveratrol's mechanism of action in cerebral I/R injury remains to be fully understood. In order to investigate the effect of resveratrol in cerebral I/R‑induced injury, male Sprague‑Dawley rats were randomly assigned to four groups: The sham‑operation group, the I/R group and the edaravone and resveratrol groups (I/R + E and I/R + R groups). Infarct volume was evaluated by 2,3,5‑tripenyltetrazolium chloride staining, brain edema was evaluated by the water content in the reperfused brain and malondialdehyde (MDA) was measured by the thiobarbituric acid method. Superoxide dismutase (SOD) levels were measured using the Total Superoxide Dismutase Assay kit. Inducible nitric oxide synthase (iNOS) levels in the hippocampus and cortex were measured by ELISA, and aquaporin 4 (AQP4) expression was measured by immunohistochemical staining and western blot analysis. The results demonstrated that resveratrol reduced the infarct volume and the incidence of brain edema and reduced neurological deficits. These outcomes were accompanied by reduced levels of MDA, iNOS and AQP4, and increased SOD levels in cerebral I/R injury. In conclusion, resveratrol protected against cerebral I/R injury by ameliorating oxidative stress and reducing AQP4 expression.

  13. β-Dystroglycan cleavage by matrix metalloproteinase-2/-9 disturbs aquaporin-4 polarization and influences brain edema in acute cerebral ischemia.

    PubMed

    Yan, W; Zhao, X; Chen, H; Zhong, D; Jin, J; Qin, Q; Zhang, H; Ma, S; Li, G

    2016-06-21

    Dystroglycan (DG) is widely expressed in various tissues, and throughout the cerebral microvasculature. It consists of two subunits, α-DG and β-DG, and the cleavage of the latter by matrix metalloproteinase (MMP)-2 and -9 underlies a number of physiological and pathological processes. However, the involvement of MMP-2/-9-mediated β-DG cleavage in cerebral ischemia remains uncertain. In astrocytes, DG is crucial for maintaining the polarization of aquaporin-4 (AQP4), which plays a role in the regulation of cytotoxic and vasogenic edema. The present study aimed to explore the effects of MMP-2/-9-mediated β-DG cleavage on AQP4 polarization and brain edema in acute cerebral ischemia. A model of cerebral ischemia was established via permanent middle cerebral artery occlusion (pMCAO) in male C57BL/6 mice. Western blotting, real-time polymerase chain reaction (PCR), immunohistochemical staining, immunofluorescent staining, electron microscopy, and light microscopy were used. Captopril was applied as a selective MMP-2/-9 inhibitor. Recombinant mouse MMP (rmMMP)-2 and -9 were used in an in vitro cleavage experiment. The present study demonstrated evidence of β-DG cleavage by MMP-2/-9 in pMCAO mouse brains; this cleavage was implicated in AQP4 redistribution and brain edema in cerebral ischemia. In addition, captopril exacerbated cytotoxic edema and ameliorated vasogenic edema at 24h after pMCAO, and alleviated brain edema and neurological deficit at 48h and 72h. In conclusion, this study provides novel insight into the effects of MMP-2/-9-mediated β-DG cleavage in acute cerebral ischemia. Such findings might facilitate the development of a therapeutic strategy for the optimization of MMP-2/-9 targeted treatment in cerebral ischemia.

  14. Effect of propofol post-treatment on blood-brain barrier integrity and cerebral edema after transient cerebral ischemia in rats.

    PubMed

    Lee, Jae Hoon; Cui, Hui Song; Shin, Seo Kyung; Kim, Jeong Min; Kim, So Yeon; Lee, Jong Eun; Koo, Bon-Nyeo

    2013-11-01

    Although propofol has been reported to offer neuroprotection against cerebral ischemia injury, its impact on cerebral edema following ischemia is not clear. The objective of this investigation is to evaluate the effects of propofol post-treatment on blood-brain barrier (BBB) integrity and cerebral edema after transient cerebral ischemia and its mechanism of action, focusing on modulation of aquaporins (AQPs), matrix metalloproteinases (MMPs), and hypoxia inducible factor (HIF)-1α. Cerebral ischemia was induced in male Sprague-Dawley rats (n = 78) by occlusion of the right middle cerebral artery for 1 h. For post-treatment with propofol, 1 mg kg(-1) min(-1) of propofol was administered for 1 h from the start of reperfusion. Nineteen rats undergoing sham surgery were also included in the investigation. Edema and BBB integrity were assessed by quantification of cerebral water content and extravasation of Evans blue, respectively, following 24 h of reperfusion. In addition, the expression of AQP-1, AQP-4, MMP-2, and MMP-9 was determined 24 h after reperfusion and the expression of HIF-1α was determined 8 h after reperfusion. Propofol post-treatment significantly reduced cerebral edema (P < 0.05) and BBB disruption (P < 0.05) compared with the saline-treated control. The expression of AQP-1, AQP-4, MMP-2, and MMP-9 at 24 h and of HIF-1α at 8 h following ischemia/reperfusion was significantly suppressed in the propofol post-treatment group (P < 0.05). Propofol post-treatment attenuated cerebral edema after transient cerebral ischemia, in association with reduced expression of AQP-1, AQP-4, MMP-2, and MMP-9. The decreased expression of AQPs and MMPs after propofol post-treatment might result from suppression of HIF-1α expression.

  15. [Clinical features of NMO according to brain MRI findings].

    PubMed

    Shimizu, Yuko

    2010-09-01

    Neuromyelitis optica (NMO) is a severe inflammatory, demyelinating disease, and its clinical characteristics include recurrent optic neuritis and longitudinally extensive transverse myelitis. The NMO-immunoglobulin (Ig) G auto-antibody (Ab), which binds to the aquaporin-4 (AQP4) water channel protein, is a marker for NMO. These clinical and immunological features have been used to distinguish NMO from multiple sclerosis (MS). In 1999, Wingerchuk et al. broadened the clinical criteria for diagnosing NMO to include "negative brain magnetic resonance imaging (MRI) at onset." However, after NMO-IgG/AQP4-Ab became a supportive criterion for diagnosing NMO, patients with NMO were frequently found to have symptomatic or asymptomatic brain lesions. In 2006, Pittock et al. reported that asymptomatic brain lesions were common in NMO, and that NMO brain lesions characteristically occurred in the hypothalamus and periventricular areas, which correspond to brain regions with high levels of AQP4 expression. Furthermore, Nakashima et al. detected abnormalities on brain MRI in 71% of NMO-IgG-positive Japanese patients. Patients with NMO have unique brain lesions that are clearly different from the lesions of patients with MS. In patients with NMO, involvement of the dorsal portion of the medulla oblongata causes intractable hiccups and nausea. Some studies described a hypothalamic lesion, and hypothalamic dysfunction could cause symptomatic hypersomnia, narcolepsy, and endocrinopathies. In some patients with NMO and NMO spectrum disorder who experience blood pressure fluctuations, vasogenic edema, manifesting as posterior reversible encephalopathy syndrome, may occur. In a recent report highlighting brain MRI with contrast enhancement, the most prominent feature that appeared to be a specific finding in NMO was "cloud-like enhancement" with multiple patchy enhancing lesions with a blurred margin. Another report showed that acute, large, edematous callosal lesions with

  16. In Situ Fluorescence Measurement of Tear Film [Na+], [K+], [Cl−], and pH in Mice Shows Marked Hypertonicity in Aquaporin-5 Deficiency

    PubMed Central

    Ruiz-Ederra, Javier; Levin, Marc H.; Verkman, A. S.

    2009-01-01

    Purpose Tear film composition depends on water and ion transport across ocular surface epithelia and on fluid secretion by lacrimal glands. The purpose of this study was to establish in situ fluorescence methods to measure tear film ionic concentrations and pH in mice and to determine whether tear film composition is sensitive to deficiency of the major ocular surface aquaporin water channels. Methods Tear film ionic concentrations and pH were measured in anesthetized mice by ratio imaging fluorescence microscopy after topical application of ion/pH-sensing, dual-wavelength fluorescent indicators. [Na+], [K+], and [Cl−] were measured with membrane-impermeant indicators developed by our laboratory, and pH was measured with bis(carboxyethyl)-carboxyfluorescein fluorescence-conjugated dextran. Measurements were performed on wild-type mice and on knockout mice lacking aquaporins AQP1, AQP3, and AQP5. Results In wild-type mice, tear film [Na+] was 139 ± 8 mM, [K+] was 48 ± 1 mM, [Cl−] was 127 ± 4 mM, and pH was 7.59 ± 0.2 (SE; n = 5–8). pH did not differ significantly in the AQP knockout mice. [Na+] was increased by approximately twofold in AQP5 null mice (230 ± 20 mM) and was greatly reduced after exposure of the ocular surface to a humidified atmosphere. [K+] was mildly reduced in AQP1 null mice. Conclusions These results establish an in situ optical methodology to measure tear film [Na+], [K+], [Cl−], and pH in living mice, without the need for fluid sampling. Tear film hypertonicity in AQP5 deficiency is likely caused by reduced transcorneal water secretion in response to evaporative water loss. PMID:19136711

  17. A collaboration of aquaporins handles water transport in relation to the estrous cycle in the bitch uterus.

    PubMed

    Aralla, M; Borromeo, V; Groppetti, D; Secchi, C; Cremonesi, F; Arrighi, S

    2009-08-01

    Fluid movement through uterine cell membranes is crucial, as it can modulate the tissue imbibition pattern in the different phases of the estrous cycle. To gain insight into the mechanisms underlying steroid-controlled water handling, the presence and distribution of aquaporins (AQPs), integral membrane channel proteins permitting rapid passive water movement, was explored in bitch uterine tissues. Immunohistochemistry and Western immunoblot analysis were used to study the presence of AQP1, AQP2, and AQP5 in the layers of the bitch uterine wall during the different estrous phases. Presence of endothelial nitric oxide-generating enzyme NO synthase (NOS3) was also investigated, as it is known that the vasodilator NOS3 might be involved in the development of uterine edema. The results demonstrated the following: (1) AQP1, AQP2, and AQP5 were present in the uterus of cycling bitches. (2) AQP1 was localized within uterine mesometrial, myometrial, and endometrial blood vessels and in the circular and longitudinal layers of myometrium. AQP1 localization and expression were unaffected by the estrous cycle. (3) The estrogenic milieu was probably at the basis of AQP2 expression in the glandular and luminal epithelium of the endometrium. (4) AQP5 water channels were present in the apical plasma membrane of uterine epithelial cells in coincidence with plasma progesterone increase. (5) NOS3 was localized in the myometrial and epithelial tissues as well as in blood vessels indicating a contribution of this vasoactive peptide to the uterine imbibition processes. Thus, we can hypothesize that a functional and distinctive collaboration exists among diverse AQPs in water handling during the different functional uterine phases.

  18. Progressive cerebral atrophy in neuromyelitis optica.

    PubMed

    Warabi, Yoko; Takahashi, Toshiyuki; Isozaki, Eiji

    2015-12-01

    We report two cases of neuromyelitis optica patients with progressive cerebral atrophy. The patients exhibited characteristic clinical features, including elderly onset, secondary progressive tetraparesis and cognitive impairment, abnormally elevated CSF protein and myelin basic protein levels, and extremely highly elevated serum anti-AQP-4 antibody titer. Because neuromyelitis optica pathology cannot switch from an inflammatory phase to the degenerative phase until the terminal phase, neuromyelitis optica rarely appears as a secondary progressive clinical course caused by axonal degeneration. However, severe intrathecal inflammation and massive destruction of neuroglia could cause a secondary progressive clinical course associated with cerebral atrophy in neuromyelitis optica patients.

  19. Sarcoidosis associated with neuromyelitis optica.

    PubMed

    Sawaya, Raja; Radwan, Wael

    2013-08-01

    Neuromyelitis optica (NMO) is an autoimmune disorder diagnosed by an elongated spinal cord lesion associated with unilateral or bilateral optic neuritis and anti-aquaporin 4 (AQP4) antibodies in the serum. It is triggered by or associated with several autoimmune diseases, but not with sarcoidosis. It responds to immunomodulators better than to steroid treatment. Sarcoidosis is an autoimmune disorder which manifests as non-caseating granulomas, usually in the lung parenchyma, but also in other tissues, including the brain. The involvement of the central nervous system in neurosarcoidosis differs considerably from that in neuromyelitis optica and the association of these two diseases concurrently in the same patient is unusual.

  20. Neuronal damage and functional deficits are ameliorated by inhibition of aquaporin and HIF1α after traumatic brain injury (TBI).

    PubMed

    Shenaq, Mohammed; Kassem, Hassan; Peng, Changya; Schafer, Steven; Ding, Jamie Y; Fredrickson, Vance; Guthikonda, Murali; Kreipke, Christian W; Rafols, José A; Ding, Yuchuan

    2012-12-15

    The present study, using a rodent model of closed-head diffuse traumatic brain injury (TBI), investigated the role of dysregulated aquaporins (AQP) 4 and 9, as well as hypoxia inducible factor -1α(HIF-1α) on brain edema formation, neuronal injury, and functional deficits. TBI was induced in adult (400-425 g), male Sprague-Dawley rats using a modified Marmarou's head impact-acceleration device (450 g weight dropped from 2m height). Animals in each treatment group were administered intravenous anti-AQP4 or -AQP9 antibodies or 2-Methoxyestradiol (2ME2, an inhibitor of HIF-1α) 30 min after injury. At 24h post-TBI, animals (n=6 each group) were sacrificed to examine the extent of brain edema by water content, as well as protein expression of AQP and HIF-1α by Western immune-blotting. At 48-hours post-TBI, neuronal injury (n=8 each group) was assessed by FluoroJade (FJ) histochemistry. Spatial learning and memory deficits were evaluated by radial arm maze (n=8 each group) up to 21 days post-TBI. Compared to non-injured controls, significant (p<0.05) increases in the expression of AQP4 and -9 were detected in the brains of injured animals. In addition, significant (p<0.05) brain edema after TBI was associated with increases (p <0.05) both in neuronal injury (FJ labeling) and neurobehavioral deficits. Selective inhibition of either AQP4 or -9, or HIF-1α significantly (p<0.05) decreased the expression of the proteins. In addition, inhibition of the AQPs and HIF-1α significantly (p<0.05) ameliorated brain edema, as well as the number of injured neurons in cortical layers II/III and V/VI, striatum and hippocampal regions CA1/CA3. Finally, compared to the non-treated TBI animals, AQP or HIF-1α inhibition significantly (p<0.01) improved neurobehavioral outcomes after TBI. Taken together, the present data supports a causal relation between HIF-AQP mediated cerebral edema, secondary neuronal injury, and tertiary behavioral deficits post-TBI. The data further suggests that

  1. Determining Membrane Protein-Lipid Binding Thermodynamics Using Native Mass Spectrometry.

    PubMed

    Cong, Xiao; Liu, Yang; Liu, Wen; Liang, Xiaowen; Russell, David H; Laganowsky, Arthur

    2016-04-06

    Membrane proteins are embedded in the biological membrane where the chemically diverse lipid environment can modulate their structure and function. However, the thermodynamics governing the molecular recognition and interaction of lipids with membrane proteins is poorly understood. Here, we report a method using native mass spectrometry (MS), to determine thermodynamics of individual ligand binding events to proteins. Unlike conventional methods, native MS can resolve individual ligand binding events and, coupled with an apparatus to control the temperature, determine binding thermodynamic parameters, such as for protein-lipid interactions. We validated our approach using three soluble protein-ligand systems (maltose binding protein, lysozyme, and nitrogen regulatory protein) and obtained similar results to those using isothermal titration calorimetry and surface plasmon resonance. We also determined for the first time the thermodynamics of individual lipid binding to the ammonia channel (AmtB), an integral membrane protein from Escherichia coli. Remarkably, we observed distinct thermodynamic signatures for the binding of different lipids and entropy-enthalpy compensation for binding lipids of variable chain length. Additionally, using a mutant form of AmtB that abolishes a specific phosphatidylglycerol (PG) binding site, we observed distinct changes in the thermodynamic signatures for binding PG, implying these signatures can identify key residues involved in specific lipid binding and potentially differentiate between specific lipid binding sites.

  2. Distribution and quantitative changes in amounts of aquaporin 1, 5 and 9 in the pig uterus during the estrous cycle and early pregnancy

    PubMed Central

    2010-01-01

    Background Aquaporins (AQPs) are a family of membrane channel proteins that facilitate bulk water transport. To date, 11 isoforms of AQPs have been reported to be expressed in the female and male reproductive systems. The purpose of our study was to determine the localization and quantitative changes in the expression of AQP1, 5 and 9 within the pig uterus during different stages of the estrous cycle and early pregnancy. Methods Immunoperoxidase and semi-quantitative immunoblotting techniques were used to examine the distribution and changes in amounts of AQP1, AQP5 and AQP9 in uteral cells of pigs at the early (Days 2-4), middle (10-12), late (14-16) stage of the luteal phase and late (18-20) stage of the follicular phase of the estrous cycle as well as on Days 14-16 and 30-32 of gestation (the onset and the end of implantation process). Results The results demonstrated that AQP1, 5, and 9 were clearly detected in all studied stages of the estrous cycle and pregnancy. AQP1 was localized within uterine blood vessels. In cyclic gilts, endometrial and myometrial expression of AQP1 protein did not change significantly but increased during gestation. AQP5 was localized in smooth muscle cells and uterine epithelial cells. Endometrial expression of AQP5 protein did not change significantly between Days 2-4 and 10-12 of the estrous cycle but increased on Days 14-16 and 18-20 as well as during early pregnancy. Myometrial expression of AQP5 did not differ significantly during the estrous cycle but increased in the pregnancy. The anti-AQP9 antibody labeled uterine epithelial cells of uterus. Endometrial expression of AQP9 did not change significantly between Days 2-4 and 10-12 of the estrous cycle but increased on Days 14-16 and 18-20 as well as during early pregnancy. Conclusions The results suggest that a functional and distinctive collaboration exists among diverse AQPs in water handling during the different uterine phases in the estrous cycle and early pregnancy. PMID

  3. Epidemiological, clinical, and immunological characteristics of neuromyelitis optica: A review.

    PubMed

    Pereira, Wildéa Lice de Carvalho Jennings; Reiche, Edna Maria Vissoci; Kallaur, Ana Paula; Kaimen-Maciel, Damacio Ramón

    2015-08-15

    The aim of this study was to review the epidemiological and clinical characteristics of neuromyelitis optica (NMO) and the immunopathological mechanisms involved in the neuronal damage. NMO is an inflammatory demyelinating autoimmune disease of the central nervous system that most commonly affects the optic nerves and spinal cord. NMO is thought to be more prevalent among non-Caucasians and where multiple sclerosis (MS) prevalence is low. NMO follows a relapsing course in more than 80-90% of cases, which is more commonly in women. It is a complex disease with an interaction between host genetic and environmental factors and the main immunological feature is the presence of anti-aquaporin 4 (AQP4) antibodies in a subset of patients. NMO is frequently associated with multiple other autoantibodies and there is a strong association between NMO with other systemic autoimmune diseases. AQP4-IgG can cause antibody-dependent cellular cytotoxicity (ADCC) when effector cells are present and complement-dependent cytotoxicity (CDC) when complement is present. Acute therapies, including corticosteroids and plasma exchange, are designed to minimize injury and accelerate recovery. Several aspects of NMO pathogenesis remain unclear. More advances in the understanding of NMO disease mechanisms are needed in order to identify more specific biomarkers to NMO diagnosis.

  4. Fingolimod-induced leukoencephalopathy in a patient with neuromyelitis optica spectrum disorder.

    PubMed

    Yoshii, Fumihito; Moriya, Yusuke; Ohnuki, Tomohide; Ryo, Masafuchi; Takahashi, Wakoh

    2016-05-01

    Fingolimod (FTY720) is used for reducing the annualized relapse rate and slowing progression of neurological disability in relapsing-remitting forms of multiple sclerosis (MS). However, its safety is not confirmed in patients with neuromyelitis optica spectrum disorder (NMOSD), who characteristically have positive aquaporin-4 (AQP-4) antibody. A 54-year-old female with a relapsing-remitting course of optic neuritis and myelitis for six years, diagnosed initially as MS, had been treated with interferon beta-1b and oral corticosteroid. Magnetic resonance imaging (MRI) consistently revealed lesions on the optic nerve and spinal cord, but never on the brainstem or cerebral white matter during acute exacerbation. After treatment was switched to fingolimod from interferon beta-1b, multiple new lesions appeared at the brainstem and cerebral white matter. Following discontinuation of fingolimod, these lesions completely cleared, concomitantly with clinical improvement. During fingolimod treatment, she was recognized to be positive for AQP-4 antibody. Fingolimod may be contraindicated in patients with NMOSD.

  5. Analysis by two-dimensional Blue Native/SDS-PAGE of membrane protein alterations in rat soleus muscle after hindlimb unloading.

    PubMed

    Basco, Davide; Nicchia, Grazia Paola; Desaphy, Jean-François; Camerino, Diana Conte; Frigeri, Antonio; Svelto, Maria

    2010-12-01

    Muscle atrophy occurring in several pathophysiological conditions determines decreases in muscle protein synthesis, increases in the rate of proteolysis and changes in muscle fiber composition. To determine the effect of muscle atrophy induced by hindlimb unloading (HU) on membrane proteins from rat soleus, a proteomic approach based on two-dimensional Blue Native/SDS-PAGE was performed. Proteomic analysis of normal and HU soleus muscle demonstrates statistically significant changes in the relative level of 36 proteins. Among the proteins identified by mass spectrometry, most are involved in pathways associated with muscle fuel utilization, indicating a shift in metabolism from oxidative to glycolytic. Moreover, immunoblotting analysis revealed an increase in aquaporin-4 (AQP4) water channel and an alteration of proteins belonging to the dystrophin-glycoprotein complex (DGC). AQP4 and DGC are regulated in soleus muscle subjected to simulated microgravity in response to compensatory mechanisms induced by muscle atrophy, and they parallel the slow-to-fast twitch conversion that occurs in soleus fibers during HU. In conclusion, the alterations of soleus muscle membrane proteome may play a pivotal role in the mechanisms involved in disuse-induced muscle atrophy.

  6. Aquaporin expression in the cerebral cortex is increased at early stages of Alzheimer disease.

    PubMed

    Pérez, Esther; Barrachina, Marta; Rodríguez, Agustín; Torrejón-Escribano, Benjamín; Boada, Mercé; Hernández, Isabel; Sánchez, Marisa; Ferrer, Isidre

    2007-01-12

    Abnormalities in the cerebral microvasculature are common in Alzheimer disease (AD). Expression levels of the water channels aquaporin 1 and aquaporin 4 (AQP1, AQP4) were examined in AD cases by gel electrophoresis and Western blotting, and densitometric values normalized with beta-actin were compared with corresponding values in age-matched controls processed in parallel. In addition, samples of cases with Pick disease (PiD) were examined for comparative purposes. A significant increase in the expression levels of AQP1 was observed in AD stage II (following Braak and Braak classification). Individual variations were seen in advanced stages which resulted in non-significant differences between AD stages V-VI and age-matched controls. No differences in AQP1 levels were observed between familial AD cases (FAD, all of them at advanced stages) and corresponding age-matched controls. Immunohistochemistry showed increased AQP1 in astrocytes at early stages of AD. Double-labelling immunofluorescence and confocal microscopy disclosed AQP1 immunoreactivity at the cell surface of astrocytes which were recognized with anti-glial fibrillary acidic protein antibodies. No differences in the levels of AQP4 were observed in AD, FAD and PiD when compared with corresponding controls. These results indicate abnormal expression of AQP1 in astrocytes in AD, and they add support to the idea that abnormal regulation of mechanisms involved in the control of water fluxes occurs at early stages in AD.

  7. Serologic diagnosis of NMO

    PubMed Central

    McKeon, A.; Leite, M.I.; Rajasekharan, S.; Lennon, V.A.; Villalobos, A.; Palace, J.; Mandrekar, J.N.; Vincent, A.; Bar-Or, A.

    2012-01-01

    Objectives: Neuromyelitis optica (NMO) immunoglobulin G (IgG) (aquaporin-4 [AQP4] IgG) is highly specific for NMO and related disorders, and autoantibody detection has become an essential investigation in patients with demyelinating disease. However, although different techniques are now used, no multicenter comparisons have been performed. This study compares the sensitivity and specificity of different assays, including an in-house flow cytometric assay and 2 commercial assays (ELISA and transfected cell-based assay [CBA]). Methods: Six assay methods (in-house or commercial) were performed in 2 international centers using coded serum from patients with NMO (35 patients), NMO spectrum disorders (25 patients), relapsing-remitting multiple sclerosis (39 patients), miscellaneous autoimmune diseases (25 patients), and healthy subjects (22 subjects). Results: The highest sensitivities were yielded by assays detecting IgG binding to cells expressing recombinant AQP4 with quantitative flow cytometry (77; 46 of 60) or visual observation (CBA, 73%; 44 of 60). The fluorescence immunoprecipitation assay and tissue-based immunofluorescence assay were least sensitive (48%–53%). The CBA and ELISA commercial assays (100% specific) yielded sensitivities of 68% (41 of 60) and 60% (36 of 60), respectively, and sensitivity of 72% (43 of 60) when used in combination. Conclusions: The greater sensitivity and excellent specificity of second-generation recombinant antigen-based assays for detection of NMO-IgG in a clinical setting should enable earlier diagnosis of NMO spectrum disorders and prompt initiation of disease-appropriate therapies. PMID:22302543

  8. Forensic application of intrarenal aquaporin-2 expression for differential diagnosis between freshwater and saltwater drowning.

    PubMed

    An, Jun-Ling; Ishida, Yuko; Kimura, Akihiko; Kondo, Toshikazu

    2010-03-01

    Aquaporins (AQPs) are a family of homologous water channel proteins. In this study, the expressions of AQP1, 2, and 4 were immunohistochemically examined in kidney samples to evaluate their forensic applicability to differentiate between freshwater drowning (FWD) and saltwater drowning (SWD). Kidney samples were obtained from 51 drowning cases (23 FWD and 28 SWD) and 19 non-drowning cases. AQP1 was expressed in the proximal tubules and glomeruli, and AQP4 was localized in the collecting ducts. However, there were no significant differences in AQP1 and AQP4 expressions among FWD, SWD, and control groups. Immunohistochemically, AQP2 was predominantly expressed in the apical plasma membrane of the collecting duct principal cells in all kidney samples of FWD and SWD. Morphometrically, AQP2 expression at the apical plasma membrane of collecting ducts was significantly enhanced in SWD group, compared with FWD and control groups. On the other hand, AQP-2 expression was significantly lower in FWD group than in control group. Moreover, in drowning cases, there was no correlation between post-submersion intervals and AQP expression. From a forensic aspect, immunohistochemical detection of AQP2 in the kidney can be considered a valuable marker to differentiate between FWD and SWD.

  9. Pretreatment with a novel aquaporin 4 inhibitor, TGN-020, significantly reduces ischemic cerebral edema

    PubMed Central

    Igarashi, Hironaka; Huber, Vincent J.; Tsujita, Mika

    2010-01-01

    We investigated the in vivo effects of a novel aquaporin 4 (AQP4) inhibitor 2-(nicotinamide)-1,3,4-thiadiazole, TGN-020, in a mouse model of focal cerebral ischemia using 7.0-T magnetic resonance imaging (MRI). Pretreatment with TGN-020 significantly reduced brain edema associated with brain ischemia, as reflected by percentage of brain swelling volume (%BSV), 12.1 ± 6.3% in the treated group, compared to (20.8 ± 5.9%) in the control group (p < 0.05), and in the size of cortical infarction as reflected by the percentage of hemispheric lesion volume (%HLV), 20.0 ± 7.6% in the treated group, compared to 30.0 ± 9.1% in the control group (p < 0.05). The study indicated the potential pharmacological use of AQP4 inhibition in reducing brain edema associated with focal ischemia. PMID:20924629

  10. High mobility group box protein-1 promotes cerebral edema after traumatic brain injury via activation of toll-like receptor 4.

    PubMed

    Laird, Melissa D; Shields, Jessica S; Sukumari-Ramesh, Sangeetha; Kimbler, Donald E; Fessler, R David; Shakir, Basheer; Youssef, Patrick; Yanasak, Nathan; Vender, John R; Dhandapani, Krishnan M

    2014-01-01

    Traumatic brain injury (TBI) is a major cause of mortality and morbidity worldwide. Cerebral edema, a life-threatening medical complication, contributes to elevated intracranial pressure (ICP) and a poor clinical prognosis after TBI. Unfortunately, treatment options to reduce post-traumatic edema remain suboptimal, due in part, to a dearth of viable therapeutic targets. Herein, we tested the hypothesis that cerebral innate immune responses contribute to edema development after TBI. Our results demonstrate that high-mobility group box protein 1 (HMGB1) was released from necrotic neurons via a NR2B-mediated mechanism. HMGB1 was clinically associated with elevated ICP in patients and functionally promoted cerebral edema after TBI in mice. The detrimental effects of HMGB1 were mediated, at least in part, via activation of microglial toll-like receptor 4 (TLR4) and the subsequent expression of the astrocytic water channel, aquaporin-4 (AQP4). Genetic or pharmacological (VGX-1027) TLR4 inhibition attenuated the neuroinflammatory response and limited post-traumatic edema with a delayed, clinically implementable therapeutic window. Human and rodent tissue culture studies further defined the cellular mechanisms demonstrating neuronal HMGB1 initiates the microglial release of interleukin-6 (IL-6) in a TLR4 dependent mechanism. In turn, microglial IL-6 increased the astrocytic expression of AQP4. Taken together, these data implicate microglia as key mediators of post-traumatic brain edema and suggest HMGB1-TLR4 signaling promotes neurovascular dysfunction after TBI.

  11. Multiple Modes of Action of the Squamocin in the Midgut Cells of Aedes aegypti Larvae

    PubMed Central

    de Paula, Sérgio Oliveira; Martins, Gustavo Ferreira; Zanuncio, José Cola

    2016-01-01

    Annonaceous acetogenins are botanical compounds with good potential for use as insecticides. In the vector, Aedes aegypti (L.) (Diptera: Culicidae), squamocin (acetogenin) has been reported to be a larvicide and cytotoxic, but the modes of action of this molecule are still poorly understood. This study evaluated the changes in the cell morphology, and in the expression of genes, for autophagy (Atg1 and Atg8), for membrane ion transporter V-ATPase, and for water channel aquaporin-4 (Aqp4) in the midgut of A. aegypti larvae exposed to squamocin from Annona mucosa Jacq. (Annonaceae). Squamocin showed cytotoxic action with changes in the midgut epithelium and digestive cells of A. aegypti larvae, increase in the expression for autophagy gene Atg1 and Atg8, decrease in the expression of V-ATPase, decrease in the expression of Aqp4 gene in LC20 and inhibition of Apq4 genes in the midgut of this vector in LC50. These multiple modes of action for squamocin are described for the first time in insects, and they are important because different sites of action of squamocin from A. mucosa may reduce the possibility of resistance of A. aegypti to this molecule. PMID:27532504

  12. KIR4.1: K+ Channel Illusion or Reality in the Autoimmune Pathogenesis of Multiple Sclerosis

    PubMed Central

    Gu, Chen

    2016-01-01

    Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). Many believe autoimmune pathogenesis plays a key role in MS, but its target(s) remains elusive. A recent study detected autoantibodies against KIR4.1, an ATP-sensitive, inward rectifier potassium channel, in nearly half of the MS patients examined. KIR4.1 channels are expressed in astrocytes. Together with aquaporin 4 (AQP4) water channels, they regulate astrocytic functions vital for myelination. Autoantibodies against AQP4 have been established as a key biomarker for neuromyelitis optica (NMO) and contributed to diagnostic and treatment strategy adjustments. Similarly, identification of KIR4.1 autoantibodies could have high therapeutic values in treating MS. Consistent with its potential role in MS, KIR4.1 dysfunction is implicated in several neurological disorders. However, the enrichment of KIR4.1 autoantibodies in MS patients is questioned by follow-up studies. Further, investigations are needed to clarify this controversy and unravel the underlying mechanisms of MS pathogenesis. PMID:27729847

  13. Aquaporin-11 (AQP11) Expression in the Mouse Brain

    PubMed Central

    Koike, Shin; Tanaka, Yasuko; Matsuzaki, Toshiyuki; Morishita, Yoshiyuki; Ishibashi, Kenichi

    2016-01-01

    Aquaporin-11 (AQP11) is an intracellular aquaporin expressed in various tissues, including brain tissues in mammals. While AQP11-deficient mice have developed fatal polycystic kidneys at one month old, the role of AQP11 in the brain was not well appreciated. In this study, we examined the AQP11 expression in the mouse brain and the brain phenotype of AQP11-deficient mice. AQP11 messenger ribonucleic acid (mRNA) and protein were expressed in the brain, but much less than in the thymus and kidney. Immunostaining showed that AQP11 was localized at the epithelium of the choroid plexus and at the endothelium of the brain capillary, suggesting that AQP11 may be involved in water transport at the choroid plexus and blood-brain barrier (BBB) in the brain. The expression of AQP4, another brain AQP expressed at the BBB, was decreased by half in AQP11-deficient mice, thereby suggesting the presence of the interaction between AQP11 and AQP4. The brain of AQP11-deficient mice, however, did not show any morphological abnormalities and the function of the BBB was intact. Our findings provide a novel insight into a water transport mechanism mediated by AQPs in the brain, which may lead to a new therapy for brain edema. PMID:27258268

  14. Molecular pathology of brain matrix metalloproteases, claudin5, and aquaporins in forensic autopsy cases with special regard to methamphetamine intoxication.

    PubMed

    Wang, Qi; Ishikawa, Takaki; Michiue, Tomomi; Zhu, Bao-Li; Guan, Da-Wei; Maeda, Hitoshi

    2014-05-01

    Methamphetamine (METH) is a highly addictive drug of abuse and toxic to the brain. Recent studies indicated that besides direct damage to dopamine and 5-HT terminals, neurotoxicity of METH may also result from its ability to modify the structure of blood-brain barrier (BBB). The present study investigated the postmortem brain mRNA and immunohistochemical expressions of matrix metalloproteases (MMPs), claudin5 (CLDN5), and aquaporins (AQPs) in forensic autopsy cases of carbon monoxide (n = 14), METH (n = 21), and phenobarbital (n = 17) intoxication, compared with mechanical asphyxia (n = 15), brain injury (n = 11), non-brain injury (n = 21), and sharp instrument injury (n = 15) cases. Relative mRNA quantification using Taqman real-time PCR assay demonstrated higher expression of AQP4 and MMP9, lower expression of CLDN5 in METH intoxication cases and lower expression of MMP2 in phenobarbital intoxication cases. Immunostaining results showed substantial interindividual variations in each group, showing no evident differences in distribution or intensity among all the causes of death. These findings suggest that METH may increase BBB permeability by altering CLDN5 and MMP9, and the self-protective system maybe activated to eliminate accumulating water from the extracellular space of the brain by up-regulating AQP4. Systematic analysis of gene expressions using real-time PCR may be a useful procedure in forensic death investigation.

  15. Metal Ion Toxins and Brain Aquaporin-4 Expression: An Overview

    PubMed Central

    Ximenes-da-Silva, Adriana

    2016-01-01

    Metal ions such as iron, zinc, and manganese are essential to metabolic functions, protein synthesis, neurotransmission, and antioxidant neuroprotective mechanisms. Conversely, non-essential metals such as mercury and lead are sources of human intoxication due to occupational activities or environmental contamination. Essential or non-essential metal accumulation in the central nervous system (CNS) results in changes in blood-brain barrier (BBB) permeability, as well as triggering microglia activation and astrocyte reactivity and changing water transport through the cells, which could result in brain swelling. Aquaporin-4 is the main water channel in the CNS, is expressed in astrocyte foot processes in brain capillaries and along the circumventricular epithelium in the ventricles, and has important physiological functions in maintaining brain osmotic homeostasis and supporting brain excitability through regulation of the extracellular space. Some evidence has pointed to a role of AQP4 during metal intoxication in the brain, where it may act in a dual form as a neuroprotector or a mediator of the development of oxidative stress in neurons and astrocytes, resulting in brain swelling and neuronal damage. This mini-review presents the way some metal ions affect changes in AQP4 expression in the CNS and discuss the ways in which water transport in brain cells can be involved in brain damage. PMID:27313504

  16. Diagnosis and classification of autoimmune optic neuropathy.

    PubMed

    Petzold, Axel; Plant, Gordon T

    2014-01-01

    The spectrum of autoimmune optic neuropathies (ON) is extending. The phenotypic spectrum includes single isolated optic neuritis (SION), relapsing isolated optic neuritis (RION), chronic relapsing inflammatory optic neuropathy (CRION), the neuromyelitis optica (NMO) spectrum disorder, multiple sclerosis associated optic neuritis (MSON) and unclassified optic neuritis (UCON) forms. Epidemiological data suggests a slight female predominance. The ethnic heritage is relevant as Caucasian patients are more likely to suffer from MSON, whilst SION, RION, CRION and NMO are more frequent in non-Caucasian patients. Importantly, prognosis for recovery of visual function is good in MSON, but poorer in NMO and CRION which also have a high chance for recurrent episodes. Testing for serum anti-AQP4 autoantibodies is advised in all patients with severe, atypical or recurrent ON because of the high diagnostic specificity. The diagnostic specificity may be aided by testing for glial biomarkers in the CSF and prognostic accuracy by testing for biomarkers for neuroaxonal degeneration. Optical coherence tomography is a highly accurate tool to document the final outcome. The current clinical classification criteria rely on the phenotype, response to treatment and presence of anti-AQP4 autoantibodies.

  17. Quantum dot single molecule tracking reveals a wide range of diffusive motions of membrane transport proteins

    NASA Astrophysics Data System (ADS)

    Crane, Jonathan M.; Haggie, Peter M.; Verkman, A. S.

    2009-02-01

    Single particle tracking (SPT) provides information about the microscopic motions of individual particles in live cells. We applied SPT to study the diffusion of membrane transport proteins in cell plasma membranes in which individual proteins are labeled with quantum dots at engineered extracellular epitopes. Software was created to deduce particle diffusive modes from quantum dot trajectories. SPT of aquaporin (AQP) water channels and cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels revealed several types of diffusion. AQP1 was freely mobile in cell membranes, showing rapid, Brownian-type diffusion. The full-length (M1) isoform of AQP4 also diffused rapidly, though the diffusion of a shorter (M23) isoform of AQP4 was highly restricted due to its supermolecular assembly in raft-like orthogonal arrays. CFTR mobility was also highly restricted, in a spring-like potential, due to its tethering to the actin cytoskeleton through PDZ-domain C-terminus interactions. The biological significance of regulated diffusion of membrane transport proteins is a subject of active investigation.

  18. Paraneoplastic neuromyelitis optica spectrum disorders: three new cases and a review of the literature.

    PubMed

    Cai, Gang; He, Dian; Chu, Lan; Dai, Qingqing; Xu, Zhu; Zhang, Yifan

    2016-01-01

    Neuromyelitis optica spectrum disorders (NMOSD) occasionally develop in patients with tumor in relation to aquaporin-4 IgG (AQP4-IgG), representing a new paraneoplastic phenomenon. We reported three patients with paraneoplastic NMOSD and provided a comprehensive review of the literature. A total of 34 cases with paraneoplastic NMOSD were identified from our own case database (n = 3) and the previous literature (n = 31). The median age at NMOSD-related symptom onset was 50.5 years, and 91% of the cases were female. 11 (32%) cases had breast carcinoma. In 15 (44%) cases, NMOSD-related symptoms preceded tumor detection [median, 4 (range 1-180) months], and in 19 (56%) cases, symptoms followed tumor detection [median, 12 (range 3-180) months]. 5/14 (36%) cases had hiccups and vomiting as the initial symptoms, with the involvement of medulla oblongata. In 10/14 (71%) cases, cervical spinal cord was involved. In contrast to idiopathic NMO, NMOSD is more likely to be paraneoplastic than in patients aged over 50 years at the onset of symptoms, especially for female patients. Breast carcinoma is the most common tumor associated with paraneoplastic NMOSD, accounting for nearly a third of all types of tumors. Paraneoplastic NMOSD usually involves medulla oblongata and cervical spinal cord. We recommend adding AQP4-IgG as an onconeural antibody, but its clinical utility warrants further investigations.

  19. Progress in Drug Treatment of Cerebral Edema.

    PubMed

    Deng, Y Y; Shen, F C; Xie, D; Han, Q P; Fang, M; Chen, C B; Zeng, H K

    2016-01-01

    Cerebral edema causes intracranial hypertension (ICH) which leads to severe outcome of patients in the clinical setting. Effective anti-edema therapy may significantly decrease the mortality in a variety of neurological conditions. At present drug treatment is a cornerstone in the management of cerebral edema. Osmotherapy has been the mainstay of pharmacologic therapy. Mannitol and hypertonic saline (HS) are the most commonly used osmotic agents. The relative safety and efficacy of HS and mannitol in the treatment of cerebral edema and reduction of enhanced ICP have been demonstrated in the past decades. Apart from its osmotic force, HS exerts anti-edema effects partly through inhibition of Na(+)-K(+)-2Cl(-) Cotransporter-1 (NKCC1) and aquaporin 4 (AQP4) expression in astrocytes. Melatonin may also reduce brain edema and exert neuroprotective effect on several central nervous system diseases through inhibition of inflammatory response. The inhibitors of Na/H exchanger, NKCC and AQP4 may attenuate brain edema formation through inhibition of excessive transportation of ion and water from blood into the cerebral tissue. In this review we survey some of the most recent findings in the drug treatment of brain edema focusing on the use of osmotherapy, melatonin and inhibitors of ion cotransporters and water channels. A better understanding of the molecular mechanism of these agents would help to improve in the clinical management of patients with brain edema.

  20. Rapamycin alleviates brain edema after focal cerebral ischemia reperfusion in rats.

    PubMed

    Guo, Wei; Feng, Guoying; Miao, Yanying; Liu, Guixiang; Xu, Chunsheng

    2014-06-01

    Brain edema is a major consequence of cerebral ischemia reperfusion. However, few effective therapeutic options are available for retarding the brain edema progression after cerebral ischemia. Recently, rapamycin has been shown to produce neuroprotective effects in rats after cerebral ischemia reperfusion. Whether rapamycin could alleviate this brain edema injury is still unclear. In this study, the rat stroke model was induced by a 1-h left transient middle cerebral artery occlusion using an intraluminal filament, followed by 48 h of reperfusion. The effects of rapamycin (250 μg/kg body weight, intraperitoneal; i.p.) on brain edema progression were evaluated. The results showed that rapamycin treatment significantly reduced the infarct volume, the water content of the brain tissue and the Evans blue extravasation through the blood-brain barrier (BBB). Rapamycin treatment could improve histological appearance of the brain tissue, increased the capillary lumen space and maintain the integrity of BBB. Rapamycin also inhibited matrix metalloproteinase 9 (MMP9) and aquaporin 4 (AQP4) expression. These data imply that rapamycin could improve brain edema progression after reperfusion injury through maintaining BBB integrity and inhibiting MMP9 and AQP4 expression. The data of this study provide a new possible approach for improving brain edema after cerebral ischemia reperfusion by administration of rapamycin.

  1. Contribution of aquaporins to cellular water transport observed by a microfluidic cell volume sensor.

    PubMed

    Heo, Jinseok; Meng, Fanjie; Hua, Susan Z

    2008-09-15

    Here we demonstrate that an impedance-based microfluidic cell volume sensor can be used to study the roles of aquaporin (AQP) in cellular water permeability and screen AQP-specific drugs. Human embryonic kidney (HEK-293) cells were transiently transfected with AQP3- or AQP4-encoding genes to express AQPs in plasma membranes. The swelling of cells in response to hypotonic stimulation was traced in real time using the sensor. Two time constants were obtained by fitting the swelling curves with a two-exponential function, a fast time constant associated with osmotic water permeability of AQP-expressing cells and a slow phase time constant associated mainly with water diffusion through lipid bilayers in the nontransfected cells. The AQP-expressing cells showed at least 10x faster osmotic water transport than control cells. Using the volume sensor, we examined the effects of Hg (2+) and Ni (2+) on the water transport via AQPs. Hg (2+) inhibited the water flux in AQP3-expressing cells irreversibly, while Ni (2+) blocked the AQP3 channels reversibly. Neither of the two ions blocked the AQP4 channels. The microfluidic volume sensor can sense changes in cell volume in real time, which enables perfusion of various reagents sequentially. It provides a convenient tool for studying the effect of reagents on the function and regulation mechanism of AQPs.

  2. Evaluation of cellular plasticity in the collecting duct during recovery from lithium-induced nephrogenic diabetes insipidus.

    PubMed

    Trepiccione, Francesco; Capasso, Giovambattista; Nielsen, Søren; Christensen, Birgitte Mønster

    2013-09-15

    The cellular morphology of the collecting duct is altered by chronic lithium treatment. We have previously shown that lithium increases the fraction of type-A intercalated cells and lowers the fraction of principal cells along the collecting duct. Moreover, type-A intercalated cells acquire a long-row distribution pattern along the tubules. In the present study, we show that these morphological changes reverse progressively after discontinuation of lithium and finally disappear after 19 days from lithium suspension. In this time frame we have identified for the first time, in vivo, a novel cellular type positive for both intercalated and principal cells functional markers, as recognized by colabeling with H(+)-ATPase/aquaporin-4 (AQP4) and anion exchanger-1 (AE-1)/AQP2 and Foxi1/AQP4. This cell type is mainly present after 6 days of lithium washout, and it disappears in parallel with the long-row pattern of the type-A intercalated cells. It usually localizes either in the middle or at the edge of the long-row pattern. Its ultrastructure resembles the intercalated cells as shown both by differential interference contrast and by electron microscopy. The time course of appearance, the localization along the collecting duct, and the ultrastructure suggest that the cells double labeled for principal and intercalated cells markers could represent a transition element driving the conversion of intercalated cells into principal cells.

  3. [Optic neuritis in juvenile idiopathic arthritis patient].

    PubMed

    Lourenço, Daniela M R; Buscatti, Izabel M; Lourenço, Benito; Monti, Fernanda C; Paz, José Albino; Silva, Clovis A

    2014-01-01

    Optic neuritis (ON) was rarely reported in juvenile idiopathic arthritis (JIA) patients, particularly in those under anti-tumor necrosis factor alpha blockage. However, to our knowledge, the prevalence of ON in JIA population has not been studied. Therefore, 5,793 patients were followed up at our University Hospital and 630 (11%) had JIA. One patient (0.15%) had ON and was reported herein. A 6-year-old male was diagnosed with extended oligoarticular JIA, and received naproxen and methotrexate subsequently replaced by leflunomide. At 11 years old, he was diagnosed with aseptic meningitis, followed by a partial motor seizure with secondary generalization. Brain magnetic resonance imaging (MRI) and electroencephalogram showed diffuse disorganization of the brain electric activity and leflunomide was suspended. Seven days later, the patient presented acute ocular pain, loss of acuity for color, blurred vision, photophobia, redness and short progressive visual loss in the right eye. A fundoscopic exam detected unilateral papilledema without retinal exudates. Orbital MRI suggested right ON. The anti-aquaporin 4 (anti-AQP4) antibody was negative. Pulse therapy with methylprednisolone was administered for five days, and subsequently with prednisone, he had clinical and laboratory improvement. In conclusion, a low prevalence of ON was observed in our JIA population. The absence of anti-AQP4 antibody and the normal brain MRI do not exclude the possibility of demyelinating disease associated with chronic arthritis. Therefore, rigorous follow up is required.

  4. A Paravascular Pathway Facilitates CSF Flow Through the Brain Parenchyma and the Clearance of Interstitial Solutes, Including Amyloid β

    PubMed Central

    Iliff, Jeffrey J.; Wang, Minghuan; Liao, Yonghong; Plogg, Benjamin A.; Peng, Weiguo; Gundersen, Georg A.; Benveniste, Helene; Vates, G. Edward; Deane, Rashid; Goldman, Steven A.; Nagelhus, Erlend A.; Nedergaard, Maiken

    2013-01-01

    Because it lacks a lymphatic circulation, the brain must clear extracellular proteins by an alternative mechanism. The cerebrospinal fluid (CSF) functions as a sink for brain extracellular solutes, but it is not clear how solutes from the brain interstitium move from the parenchyma to the CSF. We demonstrate that a substantial portion of subarachnoid CSF cycles through the brain interstitial space. On the basis of in vivo two-photon imaging of small fluorescent tracers, we showed that CSF enters the parenchyma along paravascular spaces that surround penetrating arteries and that brain interstitial fluid is cleared along paravenous drainage pathways. Animals lacking the water channel aquaporin-4 (AQP4) in astrocytes exhibit slowed CSF influx through this system and a ~70% reduction in interstitial solute clearance, suggesting that the bulk fluid flow between these anatomical influx and efflux routes is supported by astrocytic water transport. Fluorescent-tagged amyloid β, a peptide thought to be pathogenic in Alzheimer’s disease, was transported along this route, and deletion of the Aqp4 gene suppressed the clearance of soluble amyloid β, suggesting that this pathway may remove amyloid β from the central nervous system. Clearance through paravenous flow may also regulate extracellular levels of proteins involved with neurodegenerative conditions, its impairment perhaps contributing to the mis-accumulation of soluble proteins. PMID:22896675

  5. The Expression of Water and Ion Channels in Diffuse Alveolar Damage Is Not Dependent on DAD Etiology

    PubMed Central

    Del Carlo Bernardi, Fabiola; Alves de Araujo, Priscila; Mauad, Thais; Dolhnikoff, Marisa

    2016-01-01

    Introduction Aquaporins and ion channels are membrane proteins that facilitate the rapid movement of water and solutes across biological membranes. Experimental and in vitro studies reported that the function of these channels and pulmonary edema resolution are impaired in acute lung injury (ALI). Although current evidence indicates that alveolar fluid clearance is impaired in patients with ALI/diffuse alveolar damage (DAD), few human studies have addressed the alterations in pulmonary channels in this clinical condition. Additionally, it is not known whether the primary cause of DAD is a relevant variable for the channel dysfunction. Methods Autopsied lungs of 43 patients with acute respiratory failure (ARF) due to DAD of three different etiologies, non-pulmonary sepsis, H1N1 viral infection and leptospirosis, were compared to 18 normal lungs. We quantified the expression of aquaporin (AQP) 1, AQP3, AQP5, epithelial Na+ channel (ENaC) and sodium potassium ATPase (Na-K-ATPase) in the alveolar septum using immunohistochemistry and image analysis. Results The DAD group presented with increased expression of AQP3, AQP5 and Na-K-ATPase and decreased expression of ENaC compared to controls. However, there was no difference in protein expression within the DAD groups of different etiologies. Conclusion Water and ion channels are altered in patients with ARF due to DAD. The cause of DAD does not seem to influence the level of impairment of these channels. PMID:27835672

  6. Localization of Na(+)-K(+)-ATPase α/β, Na(+)-K(+)-2Cl-cotransporter 1 and aquaporin-5 in human eccrine sweat glands.

    PubMed

    Zhang, Mingjun; Zeng, Shaopeng; Zhang, Lei; Li, Haihong; Chen, Lu; Zhang, Xiang; Li, Xuexue; Lin, Changmin; Shu, Shenyou; Xie, Sitian; He, Yunpu; Mao, Xiaoyan; Peng, Lihong; Shi, Lungang; Yang, Lvjun; Tang, Shijie; Fu, Xiaobing

    2014-10-01

    In order to evaluate the function of the repaired or regenerated eccrine sweat glands, we must first localize the proteins involved in sweat secretion and absorption in normal human eccrine sweat glands. In our studies, the cellular localization of Na(+)-K(+)-ATPase α/β, Na(+)-K(+)-2Cl-cotransporter 1 (NKCC1) and aquaporin-5 (AQP5) in eccrine sweat glands were detected by immunoperoxidase labeling. The results showed that Na(+)-K(+)-ATPase α was immunolocalized in the cell membrane of the basal layer and suprabasal layer cells of the epidermis, the basolateral membrane of the secretory coils, and the cell membrane of the outer cells and the basolateral membrane of the luminal cells of the ducts. The localization of Na(+)-K(+)-ATPase β in the secretory coils was the same as Na(+)-K(+)-ATPase α, but Na(+)-K(+)-ATPase β labeling was absent in the straight ducts and epidermis. NKCC1 labeling was seen only in the basolateral membrane of the secretory coils. AQP5 was strongly localized in the apical membrane and weakly localized in the cytoplasm of secretory epithelial cells. The different distribution of these proteins in eccrine sweat glands was related to their functions in sweat secretion and absorption.

  7. Membrane domain specificity in the spatial distribution of aquaporins 5, 7, 9, and 11 in efferent ducts and epididymis of rats.

    PubMed

    Hermo, Louis; Schellenberg, Morgan; Liu, Lauren Ye; Dayanandan, Bama; Zhang, Tong; Mandato, Craig A; Smith, Charles E

    2008-12-01

    Water content within the epididymis of the male reproductive system is stringently regulated to promote sperm maturation. Several members of the aquaporin (AQP) family of water channel-forming integral membrane proteins have been identified in epididymal cells, but expression profiling for this epithelium is presently incomplete, and no AQP isoform has yet been identified on basolateral plasma membranes of these cells. In this study, we explored AQP expression by RT-PCR and light microscopy immunolocalizations using peroxidase and wide-field fluorescence techniques. The results indicate that several AQPs are coexpressed in the epididymis including AQP 5, 7, 9, and 11. Immunolocalizations suggested complex patterns in the spatial distribution of these AQPs. In principal cells, AQP 9 and 11 were present mainly on microvilli, whereas AQP 7 was localized primarily to lateral and then to basal plasma membranes in a region-specific manner. AQP 5 was also expressed regionally but was associated with membranes of endosomes. Additionally, AQPs were expressed by some but not all basal (AQP 7 and 11), clear (AQP 7 and 9), and halo (AQP 7 and 11) cells. These findings indicate unique associations of AQPs with specific membrane domains in a cell type- and region-specific manner within the epididymis of adult animals.

  8. Membrane Domain Specificity in the Spatial Distribution of Aquaporins 5, 7, 9, and 11 in Efferent Ducts and Epididymis of Rats

    PubMed Central

    Hermo, Louis; Schellenberg, Morgan; Liu, Lauren Ye; Dayanandan, Bama; Zhang, Tong; Mandato, Craig A.; Smith, Charles E.

    2008-01-01

    Water content within the epididymis of the male reproductive system is stringently regulated to promote sperm maturation. Several members of the aquaporin (AQP) family of water channel–forming integral membrane proteins have been identified in epididymal cells, but expression profiling for this epithelium is presently incomplete, and no AQP isoform has yet been identified on basolateral plasma membranes of these cells. In this study, we explored AQP expression by RT-PCR and light microscopy immunolocalizations using peroxidase and wide-field fluorescence techniques. The results indicate that several AQPs are coexpressed in the epididymis including AQP 5, 7, 9, and 11. Immunolocalizations suggested complex patterns in the spatial distribution of these AQPs. In principal cells, AQP 9 and 11 were present mainly on microvilli, whereas AQP 7 was localized primarily to lateral and then to basal plasma membranes in a region-specific manner. AQP 5 was also expressed regionally but was associated with membranes of endosomes. Additionally, AQPs were expressed by some but not all basal (AQP 7 and 11), clear (AQP 7 and 9), and halo (AQP 7 and 11) cells. These findings indicate unique associations of AQPs with specific membrane domains in a cell type– and region-specific manner within the epididymis of adult animals. (J Histochem Cytochem 56:1121–1135, 2008) PMID:18796408

  9. An Herbal Galactagogue Mixture Increases Milk Production and Aquaporin Protein Expression in the Mammary Glands of Lactating Rats

    PubMed Central

    Liu, Haibin; Hua, Ying; Luo, Hui; Shen, Zhaojun; Tao, Xuejiao

    2015-01-01

    Background. Herbal galactagogues have been increasingly used to treat postpartum hypogalactia. The mechanism of action of herbal galactagogues remains unclear. The purpose of this study was to investigate the effect of an herbal galactagogue mixture on milk production and aquaporin (AQP) expression in lactating rats. Methods. Thirty female Sprague Dawley rats were randomized into virgin, lactating + H2O, and lactating + galactagogue groups (n = 10 per group). Lactating rats were administered the decoction of an herbal galactagogue mixture by oral gavage or the same amount of distilled water. Results. The herbal decoction significantly increased milk production in lactating rats (P < 0.05). Both immunohistochemical staining and western blot showed that protein levels of AQP-3 and AQP-5 were significantly increased during lactation compared with virgin stage and the herbal decoction further elevated their expression (P < 0.05). AQP-1 was predominantly expressed in the capillaries whereas AQP-3 and AQP-5 were mainly detected in the epithelial cells and ducts of the mammary glands. Conclusion. The expression of AQPs in the mammary glands of rats was developmentally regulated. Herbal galactagogues might have increased milk secretion by regulating the expression and function of AQPs in the mammary glands. PMID:26075000

  10. Salvianolic acid B improves bone marrow-derived mesenchymal stem cell differentiation into alveolar epithelial cells type I via Wnt signaling.

    PubMed

    Gao, Peng; Yang, Jingxian; Gao, Xi; Xu, Dan; Niu, Dongge; Li, Jinglin; Wen, Qingping

    2015-08-01

    Acute lung injury (ALI) is among the most common causes of mortality in intensive care units. Previous studies have suggested that bone marrow-derived mesenchymal stem cells (BMSCs) may attenuate pulmonary edema. In addition, alveolar epithelial cells type I (ATI) are involved in reducing the alveolar edema in response to ALI. However, the mechanism involved in improving the efficiency of differentiation of MSCs into ATI remains to be elucidated. In the present study, the effect of salvianolic acid B (Sal B) on the differentiation of BMSCs into ATI and the activities of the Wnt signaling pathways were investigated. The BMSCs were supplemented with conditioned medium (CM). The groups were as follows: i) CM group: BMSCs were supplemented with CM; ii) lithium chloride (LiCl) group: BMSCs were supplemented with CM and 5 mM LiCl; iii) Sal B group: BMSCs were supplemented with CM and 10 mM Sal B. The samples were collected and assessed on days 7 and 14. It was revealed that aquaporin (AQP)-5 and T1α were expressed in BMSCs, and induction with LiCl or Sal B increased the expression of AQP-5 and T1α. Furthermore, the Wnt-1 and Wnt-3a signaling pathways were activated during the differentiation of BMSCs into ATI. In conclusion, it was suggested that the promotive effects of Sal B on the differentiation of BMSCs into ATI occurred through the activation of Wnt signaling pathways.

  11. Membrane proteins bind lipids selectively to modulate their structure and function

    PubMed Central

    Allison, Timothy M.; Ulmschneider, Martin B.; Degiacomi, Matteo T.; Baldwin, Andrew J.; Robinson, Carol V.

    2014-01-01

    Previous studies have established that the folding, structure and function of membrane proteins are influenced by their lipid environments1-7 and that lipids can bind to specific sites, for example in potassium channels8. Fundamental questions remain however regarding the extent of membrane protein selectivity toward lipids. Here we report a mass spectrometry (MS) approach designed to determine the selectivity of lipid binding to membrane protein complexes. We investigate the mechanosensitive channel of large conductance (MscL), aquaporin Z (AqpZ), and the ammonia channel (AmtB) using ion mobility MS (IM-MS), which reports gas-phase collision cross sections. We demonstrate that folded conformations of membrane protein complexes can exist in the gas-phase. By resolving lipid-bound states we then rank bound lipids based on their ability to resist gas phase unfolding and thereby stabilize membrane protein structure. Results show that lipids bind non-selectively and with high avidity to MscL, all imparting comparable stability, the highest-ranking lipid however is phosphatidylinositol phosphate, in line with its proposed functional role in mechanosensation9. AqpZ is also stabilized by many lipids with cardiolipin imparting the most significant resistance to unfolding. Subsequently, through functional assays, we discover that cardiolipin modulates AqpZ function. Analogous experiments identify AmtB as being highly selective for phosphatidylglycerol prompting us to obtain an X-ray structure in this lipid membrane-like environment. The 2.3Å resolution structure, when compared with others obtained without lipid bound, reveals distinct conformational changes that reposition AmtB residues to interact with the lipid bilayer. Overall our results demonstrate that resistance to unfolding correlates with specific lipid-binding events enabling distinction of lipids that merely bind from those that modulate membrane protein structure and/or function. We anticipate that these

  12. TRPM8 Ion Channels Differentially Modulate Proliferation and Cell Cycle Distribution of Normal and Cancer Prostate Cells

    PubMed Central

    Valero, María Ll.; Mello de Queiroz, Fernanda; Stühmer, Walter; Viana, Félix; Pardo, Luis A.

    2012-01-01

    Overexpression of the cation-permeable channel TRPM8 in prostate cancers might represent a novel opportunity for their treatment. Inhibitors of TRPM8 reduce the growth of prostate cancer cells. We have used two recently described and highly specific blockers, AMTB and JNJ41876666, and RNAi to determine the relevance of TRPM8 expression in the proliferation of non-tumor and tumor cells. Inhibition of the expression or function of the channel reduces proliferation rates and proliferative fraction in all tumor cells tested, but not of non-tumor prostate cells. We observed no consistent acceleration of growth after stimulation of the channel with menthol or icilin, indicating that basal TRPM8 expression is enough to sustain growth of prostate cancer cells. PMID:23251635

  13. Ammonium Transport Proteins with Changes in One of the Conserved Pore Histidines Have Different Performance in Ammonia and Methylamine Conduction

    PubMed Central

    Shao, Qiang; Javelle, Arnaud; Yang, Huaiyu; Zhu, Weiliang; Merrick, Mike

    2013-01-01

    Two conserved histidine residues are located near the mid-point of the conduction channel of ammonium transport proteins. The role of these histidines in ammonia and methylamine transport was evaluated by using a combination of in vivo studies, molecular dynamics (MD) simulation, and potential of mean force (PMF) calculations. Our in vivo results showed that a single change of either of the conserved histidines to alanine leads to the failure to transport methylamine but still facilitates good growth on ammonia, whereas double histidine variants completely lose their ability to transport both methylamine and ammonia. Molecular dynamics simulations indicated the molecular basis of the in vivo observations. They clearly showed that a single histidine variant (H168A or H318A) of AmtB confines the rather hydrophobic methylamine more strongly than ammonia around the mutated sites, resulting in dysfunction in conducting the former but not the latter molecule. PMF calculations further revealed that the single histidine variants form a potential energy well of up to 6 kcal/mol for methylamine, impairing conduction of this substrate. Unlike the single histidine variants, the double histidine variant, H168A/H318A, of AmtB was found to lose its unidirectional property of transporting both ammonia and methylamine. This could be attributed to a greatly increased frequency of opening of the entrance gate formed by F215 and F107, in this variant compared to wild-type, with a resultant lowering of the energy barrier for substrate to return to the periplasm. PMID:23667517

  14. Ammonium transport proteins with changes in one of the conserved pore histidines have different performance in ammonia and methylamine conduction.

    PubMed

    Wang, Jinan; Fulford, Tim; Shao, Qiang; Javelle, Arnaud; Yang, Huaiyu; Zhu, Weiliang; Merrick, Mike

    2013-01-01

    Two conserved histidine residues are located near the mid-point of the conduction channel of ammonium transport proteins. The role of these histidines in ammonia and methylamine transport was evaluated by using a combination of in vivo studies, molecular dynamics (MD) simulation, and potential of mean force (PMF) calculations. Our in vivo results showed that a single change of either of the conserved histidines to alanine leads to the failure to transport methylamine but still facilitates good growth on ammonia, whereas double histidine variants completely lose their ability to transport both methylamine and ammonia. Molecular dynamics simulations indicated the molecular basis of the in vivo observations. They clearly showed that a single histidine variant (H168A or H318A) of AmtB confines the rather hydrophobic methylamine more strongly than ammonia around the mutated sites, resulting in dysfunction in conducting the former but not the latter molecule. PMF calculations further revealed that the single histidine variants form a potential energy well of up to 6 kcal/mol for methylamine, impairing conduction of this substrate. Unlike the single histidine variants, the double histidine variant, H168A/H318A, of AmtB was found to lose its unidirectional property of transporting both ammonia and methylamine. This could be attributed to a greatly increased frequency of opening of the entrance gate formed by F215 and F107, in this variant compared to wild-type, with a resultant lowering of the energy barrier for substrate to return to the periplasm.

  15. Gene Deletions Resulting in Increased Nitrogen Release by Azotobacter vinelandii: Application of a Novel Nitrogen Biosensor

    PubMed Central

    Eberhart, Lauren J.; Ohlert, Janet M.; Knutson, Carolann M.; Plunkett, Mary H.

    2015-01-01

    Azotobacter vinelandii is a widely studied model diazotrophic (nitrogen-fixing) bacterium and also an obligate aerobe, differentiating it from many other diazotrophs that require environments low in oxygen for the function of the nitrogenase. As a free-living bacterium, A. vinelandii has evolved enzymes and transporters to minimize the loss of fixed nitrogen to the surrounding environment. In this study, we pursued efforts to target specific enzymes and further developed screens to identify individual colonies of A. vinelandii producing elevated levels of extracellular nitrogen. Targeted deletions were done to convert urea into a terminal product by disrupting the urease genes that influence the ability of A. vinelandii to recycle the urea nitrogen within the cell. Construction of a nitrogen biosensor strain was done to rapidly screen several thousand colonies disrupted by transposon insertional mutagenesis to identify strains with increased extracellular nitrogen production. Several disruptions were identified in the ammonium transporter gene amtB that resulted in the production of sufficient levels of extracellular nitrogen to support the growth of the biosensor strain. Further studies substituting the biosensor strain with the green alga Chlorella sorokiniana confirmed that levels of nitrogen produced were sufficient to support the growth of this organism when the medium was supplemented with sufficient sucrose to support the growth of the A. vinelandii in coculture. The nature and quantities of nitrogen released by urease and amtB disruptions were further compared to strains reported in previous efforts that altered the nifLA regulatory system to produce elevated levels of ammonium. These results reveal alternative approaches that can be used in various combinations to yield new strains that might have further application in biofertilizer schemes. PMID:25888177

  16. Structural determinants of NH3 and NH4+ transport by mouse Rhbg, a renal Rh glycoprotein.

    PubMed

    Abdulnour-Nakhoul, Solange; Le, Trang; Rabon, Edd; Hamm, L Lee; Nakhoul, Nazih L

    2016-12-01

    Renal Rhbg is localized to the basolateral membrane of intercalated cells and is involved in NH3/NH4(+) transport. The structure of Rhbg is not yet resolved; however, a high-resolution crystal structure of AmtB, a bacterial homolog of Rh, has been determined. We aligned the sequence of Rhbg to that of AmtB and identified important sites of Rhbg that may affect transport. Our analysis positioned three conserved amino acids, histidine 183 (H183), histidine 342 (H342), and tryptophan 230 (W230), within the hydrophobic pore where they presumably serve to control NH3 transport. A fourth residue, phenylalanine 128 (F128) was positioned at the upper vestibule, presumably contributing to recruitment of NH4(+) We generated three mutations each of H183, H342, W230, and F128 and expressed them in frog oocytes. Immunolabeling showed that W230 and F128 mutants were localized to the cell membrane, whereas H183 and H342 staining was diffuse and mostly intracellular. To determine function, we compared measurements of NH3/NH4(+) and methyl amine (MA)/methyl ammonium (MA(+))-induced currents, intracellular pH, and surface pH (pHs) among oocytes expressing the mutants, Rhbg, or injected with H2O. In H183 and W230 mutants, NH4(+)-induced current and intracellular acidification were inhibited compared with that of Rhbg, and MA-induced intracellular alkalinization was completely absent. Expression of H183A or W230A mutants inhibited NH3/NH4(+)- and MA/MA(+)-induced decrease in pHs to the level observed in H2O-injected oocytes. Mutations of F128 did not significantly affect transport of NH3 or NH4(+) These data demonstrated that mutating H183 or W230 caused loss of function but not F128. H183 and H342 may affect membrane expression of the transporter.

  17. Aquaporin 4 antibody [NMO Ab] status in patients with severe optic neuritis in India.

    PubMed

    Ambika, Selvakumar; Balasubramanian, Mahalakshmi; Theresa, Lily; Veeraputhiran, Akila; Arjundas, Deepak

    2015-12-01

    Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the central nervous system that causes attacks of optic neuritis and transverse myelitis. The discovery of a specific serum marker for NMO-IgG antibody [aquaporin 4 antibody/AQP4 Ab] has revolutionised the treatment of demyelinating diseases. Severe vision loss can be seen in optic neuritis (ON) associated with both multiple sclerosis (MS) and NMO. Identifying this antibody in optic neuritis patients can help us to establish the likelihood of these patients developing NMO (Jarius et al. Neurol Sci 298:158-162, 2010). It is important to differentiate these two entities as the treatment strategies of MS and NMO are different. To the best of our knowledge, there is no published literature regarding the importance of identifying this antibody in severe optic neuritis in Indian patients. Hence we decided to screen our severe optic neuritis patients for this AQP4 Ab. To investigate the presence of aquaporin 4 antibody and determine its prognostic value for visual and neurological outcome, in patients with bilateral and recurrent [severe] ON without any previous neurological manifestations presenting to a neuro-ophthalmology clinic in India. Single centre, prospective study. 40 patients (27 female patients and 13 male) with severe optic neuritis [patients with no visual improvement by 4 weeks from onset of vision loss] who presented either as recurrent attacks or as bilateral and severe optic neuritis between January 2010 and June 2011 were enrolled. Clinical features, visual outcome and sequential neurological events were compared between the seropositive and the seronegative groups. Aquaporin 4 antibodies were detected from serum using ELISA technique and IIF technique. Presence of this antibody in the serum was considered to be seropositive status and patients who did not have this antibody were considered seronegatives. AQP4 antibodies were detected in 8 of the 40 patients with severe ON (20 %).The

  18. Effects of Acupuncture at GV20 and ST36 on the Expression of Matrix Metalloproteinase 2, Aquaporin 4, and Aquaporin 9 in Rats Subjected to Cerebral Ischemia/Reperfusion Injury

    PubMed Central

    Sun, Hua; Chen, Suhui; Wang, Fuming

    2014-01-01

    Background/Purpose Ischemic stroke is characterized by high morbidity and mortality worldwide. Matrix metalloproteinase 2 (MMP2), aquaporin (AQP) 4, and AQP9 are linked to permeabilization of the blood-brain barrier (BBB) in cerebral ischemia/reperfusion injury (CIRI). BBB disruption, tissue inflammation, and MMP/AQP upregulation jointly provoke brain edema/swelling after CIRI, while acupuncture and electroacupuncture can alleviate CIRI symptoms. This study evaluated the hypothesis that acupuncture and electroacupuncture can similarly exert neuroprotective actions in a rat model of middle cerebral artery occlusion (MCAO) by modulating MMP2/AQP4/APQ9 expression and inflammatory cell infiltration. Methods Eighty 8-week-old Sprague-Dawley rats were randomly divided into sham group S, MCAO model group M, acupuncture group A, electroacupuncture group EA, and edaravone group ED. The MCAO model was established by placement of a suture to block the middle carotid artery, and reperfusion was triggered by suture removal in all groups except group S. Acupuncture and electroacupuncture were administered at acupoints GV20 (governing vessel-20) and ST36 (stomach-36). Rats in groups A, EA, and ED received acupuncture, electroacupuncture, or edaravone, respectively, immediately after MCAO. Neurological function (assessed using the Modified Neurological Severity Score), infarct volume, MMP2/AQP4/AQP9 mRNA and protein expression, and inflammatory cell infiltration were all evaluated at 24 h post-reperfusion. Results Acupuncture and electroacupuncture significantly decreased infarct size and improved neurological function. Furthermore, target mRNA and protein levels and inflammatory cell infiltration were significantly reduced in groups A, EA, and ED vs. group M. However, MMP2/AQP levels and inflammatory cell infiltration were generally higher in groups A and EA than in group ED except MMP2 mRNA levels. Conclusions Acupuncture and electroacupuncture at GV20 and ST36 both exercised

  19. Acetazolamide lowers intracranial pressure and modulates the cerebrospinal fluid secretion pathway in healthy rats.

    PubMed

    Uldall, Maria; Botfield, Hannah; Jansen-Olesen, Inger; Sinclair, Alexandra; Jensen, Rigmor

    2017-04-03

    Acetazolamide is one of the most widely used drugs for lowering intracranial pressure (ICP) and is believed to reduce cerebrospinal fluid (CSF) secretion via its action on the choroid plexus (CP). In the CP the main driving force for CSF secretion is primarily active transport of Na(+) ions facilitated by the Na/K ATPase. Transmembrane water channels, known as aquaporins (AQP), are also present in the CP and play an important role in the movement of water. In the present study, we investigated the effect of a single dose acetazolamide on the activity of the Na/K ATPase and ICP. Furthermore, we investigated the expression of Na/K ATPase, AQP1 and AQP4 in the CP tissue following acetazolamide treatment. 12 female Sprague Dawley rats were randomized into two groups; one group received 200mg acetazolamide and the other vehicle treatment. All animals were subjected to ICP recordings and the CP tissue was collected for qPCR and western blot analysis. The effect of acetazolamide on the Na/K ATPase activity was evaluated in an in vitro assay of primary CP epithelial cells isolated from rats. Acetazolamide significantly lowered ICP within 10min of injection compared to the vehicle group (P<0.05), reaching a maximum reduction at 55min 66±4% (P<0.00001). Acetazolamide also significantly decreased the activity of the Na/K ATPase in CP epithelial cells compared to vehicle (P=0.0022). Acetazolamide did not change the AQP1, AQP4 or Na/K ATPase mRNA content in the CP tissue. However, we did record an increase in the amount of AQP1 (p=0.0152) and Na/K ATPase (p=0.0411) protein in the membrane fraction of the CP, but not AQP4 (p=0.0649). A single dose of acetazolamide lowers ICP and modulates the CSF secretion pathway in healthy rats - Firstly, by inhibiting the Na/K ATPase to slow the CSF production, secondly, by increasing AQP1 and Na/K ATPase protein in the membrane of the CP epithelial cells.

  20. Role of Aquaporin 0 in lens biomechanics.

    PubMed

    Sindhu Kumari, S; Gupta, Neha; Shiels, Alan; FitzGerald, Paul G; Menon, Anil G; Mathias, Richard T; Varadaraj, Kulandaiappan

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5(-/-)), AQP0 KO (heterozygous KO: AQP0(+/-); homozygous KO: AQP0(-/-); all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0(+/-) lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and together they help to confer

  1. Molecular and cellular regulation of water homeostasis in anuran amphibians by aquaporins.

    PubMed

    Suzuki, Masakazu; Tanaka, Shigeyasu

    2009-07-01

    Aquaporins (AQPs) are water channel proteins important for transcellular water transport. Anuran AQP family consists of at least AQP0-AQP5, AQP7-AQP10, and two anuran-specific types, designated as AQPa1 and AQPa2. In Hyla japonica, AQP2 (AQP-h2K) and two forms of AQPa2 (AQP-h2 and AQP-h3) reside in the tight-junctioned epithelial cells of three major osmoregulatory organs, i.e. AQP-h2K in the kidney, AQP-h2 in the urinary bladder, and both AQP-h2 and AQP-h3 in the ventral pelvic skin. They show translocation from the cytoplasmic pool to the apical plasma membrane in response to arginine vasotocin (AVT), thereby regulating water transport across the apical membrane. Tissue distribution of AQPa2 in five anuran species, from aquatic to arboreal habitats, suggests that AQP-h2 is a urinary bladder-type AQP, while AQP-h3 is a ventral pelvic skin-type AQP. Further, AQP-h2K seems to be specific to the kidney. On the other hand, Hyla AQP3 (AQPh3BL)is located in the basolateral plasma membrane of the tight epithelial cells, irrespective of AVT stimulation. These findings suggest that anuran AVT-dependent osmoregulatory organs utilize AQP3 at the exit site of the transepithelial water transport, whereas at the entry site they basically adopt different AQPs as translocatable water channels: h2-like AQPa2 in the urinary bladder, h3-like AQPa2 in the pelvic skin, andAQP2 in the kidney. Anuran AQP3 also shows an extensive distribution over the integument, and is located along the basolateral plasma membrane of principal cells of the epidermis. It is possible that anuran AQP3might protect the epidermis against cutaneous water loss by supplying water and glycerol. In addition,immunohistochemical studies suggest that anuran AQP3 and AQP5 might be involved in the isoosmotic fluid secretion from the mucous glands and Xenopus small granular glands, possibly aiding maintenance of the moist skin, cutaneous gas exchange, and thermoregulation. Intriguingly, genomic and molecular

  2. The history of neuromyelitis optica

    PubMed Central

    2013-01-01

    The discovery of a novel serum autoantibody (termed NMO-IgG or AQP4-Ab) in a subset of patients in 2004 has revived interest in neuromyelitis optica (NMO). While the history of classical multiple sclerosis has been extensively studied, only little is known about the history of NMO. In the present article, we provide a comprehensive review of the early history of this rare but intriguing syndrome. We trace the origins of the concept of NMO in the 19th century medical literature and follow its evolution throughout the 20th and into the 21st century. Finally, we discuss recent proposals to revise the concept of NMO and explain why there is indeed a need for a more systematic and descriptive nomenclature. PMID:23320783

  3. Anti-N-methyl-d-aspartate receptor encephalitis in a patient with neuromyelitis optica spectrum disorders.

    PubMed

    Luo, Jing-Jing; Lv, He; Sun, Wei; Zhao, Juan; Hao, Hong-Jun; Gao, Feng; Huang, Yi-Ning

    2016-07-01

    We described a female patient with anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis occurring sequentially with neuromyelitis optica spectrum disorders (NMOSD). The 19-year-old patient initially presented a diencephalic syndrome with aquaporin-4 immunoglobulin G antibodies (AQP4-IgG) and brain lesions which involving bilateral medial temporal lobes and periependymal surfaces of the third ventricle on magnetic resonance imaging (MRI). Ten months later, the patient developed cognitive impairment, psychiatric symptoms and dyskinesia with left basal ganglia lesions on brain MRI. Meanwhile, the anti-NMDAR antibodies were positive in the patient's serum and cerebrospinal fluid, while the screening tests for an ovarian teratoma and other tumors were all negative. Hence, the patient was diagnosed NMOSD and anti-NMDAR encephalitis followed by low-dose rituximab treatment with a good response. This case was another evidence for demyelinating syndromes overlapping anti-NMDAR encephalitis in Chinese patients.

  4. Visual evoked potentials in neuromyelitis optica and its spectrum disorders.

    PubMed

    Ringelstein, Marius; Kleiter, Ingo; Ayzenberg, Ilya; Borisow, Nadja; Paul, Friedemann; Ruprecht, Klemens; Kraemer, Markus; Cohn, Eva; Wildemann, Brigitte; Jarius, Sven; Hartung, Hans-Peter; Aktas, Orhan; Albrecht, Philipp

    2014-04-01

    Optic neuritis (ON) is a key feature of neuromyelitis optica (NMO). Recently, NMO patients of predominantly Afro-Brazilian origin were evaluated by visual evoked potentials (VEPs) and showed marked amplitude reductions. Here, we analyzed VEPs in a predominantly Caucasian cohort, consisting of 43 patients with definite NMO, 18 with anti-aquaporin (AQP) 4 antibody-seropositive NMO spectrum disorders and 61 matched healthy controls. We found reduced amplitudes in only 12.3%, prolonged latencies in 41.9% and a lack of response in 14.0% of NMO eyes. Delayed P100 latencies in eyes without prior ON suggested this was a subclinical affection. The data indicate heterogenous patterns in NMO, warranting further investigation.

  5. Astrocytic laminin regulates pericyte differentiation and maintains blood brain barrier integrity

    NASA Astrophysics Data System (ADS)

    Yao, Yao; Chen, Zu-Lin; Norris, Erin H.; Strickland, Sidney

    2014-03-01

    Blood brain barrier (BBB) breakdown is not only a consequence of but also contributes to many neurological disorders, including stroke and Alzheimer’s disease. How the basement membrane (BM) contributes to the normal functioning of the BBB remains elusive. Here we use conditional knockout mice and an acute adenovirus-mediated knockdown model to show that lack of astrocytic laminin, a brain-specific BM component, induces BBB breakdown. Using functional blocking antibody and RNAi, we further demonstrate that astrocytic laminin, by binding to integrin α2 receptor, prevents pericyte differentiation from the BBB-stabilizing resting stage to the BBB-disrupting contractile stage, and thus maintains the integrity of BBB. Additionally, loss of astrocytic laminin decreases aquaporin-4 (AQP4) and tight junction protein expression. Altogether, we report a critical role for astrocytic laminin in BBB regulation and pericyte differentiation. These results indicate that astrocytic laminin maintains the integrity of BBB through, at least in part, regulation of pericyte differentiation.

  6. Neuromyelitis optica-IgG (aquaporin-4) autoantibodies in immune mediated optic neuritis.

    PubMed

    Petzold, A; Pittock, S; Lennon, V; Maggiore, C; Weinshenker, B G; Plant, G T

    2010-01-01

    The clinical course of immune mediated optic neuritis (ON) will depend on the specific underlying inflammatory disease. These disorders have traditionally been classified according to clinical and MRI findings. Aquaporin-4 (AQP4) autoantibodies (neuromyelitis optica-IgG (NMO-IgG)) may have diagnostic and prognostic value in patients who present with isolated ON. In this prospective study, NMO-IgG was evaluated in 114 patients with ON in the following contexts: neuromyelitis optica (NMO), multiple sclerosis (MSON), chronic relapsing inflammatory ON (CRION), relapsing isolated ON (RION) and single isolated ON (SION). The proportion seropositive was 56% for NMO (n = 9), 0% for MSON (n = 28) and 5% for the remaining diagnostic categories (CRION (n = 19), RION (n = 17) and SION (n = 41)). Testing for NMO-IgG in patients with recurrent or severe ON who lack convincing evidence of MS may identify patients who would benefit from immunosuppression rather than MS directed immunomodulatory therapies.

  7. Aquaporins in the Spinal Cord

    PubMed Central

    Oklinski, Michal K.; Skowronski, Mariusz T.; Skowronska, Agnieszka; Rützler, Michael; Nørgaard, Kirsten; Nieland, John D.; Kwon, Tae-Hwan; Nielsen, Søren

    2016-01-01

    Aquaporins (AQPs) are water channel proteins robustly expressed in the central nervous system (CNS). A number of previous studies described the cellular expression sites and investigated their major roles and function in the brain and spinal cord. Among thirteen different mammalian AQPs, AQP1 and AQP4 have been mainly studied in the CNS and evidence has been presented that they play important roles in the pathogenesis of CNS injury, edema and multiple diseases such as multiple sclerosis, neuromyelitis optica spectrum disorders, amyotrophic lateral sclerosis, glioblastoma multiforme, Alzheimer’s disease and Parkinson’s disease. The objective of this review is to highlight the current knowledge about AQPs in the spinal cord and their proposed roles in pathophysiology and pathogenesis related to spinal cord lesions and injury. PMID:27941618

  8. Progress in AQP Research and New Developments in Therapeutic Approaches to Ischemic and Hemorrhagic Stroke

    PubMed Central

    Previch, Lauren E.; Ma, Linlin; Wright, Joshua C.; Singh, Sunpreet; Geng, Xiaokun; Ding, Yuchuan

    2016-01-01

    Cerebral edema often manifests after the development of cerebrovascular disease, particularly in the case of stroke, both ischemic and hemorrhagic. Without clinical intervention, the influx of water into brain tissues leads to increased intracranial pressure, cerebral herniation, and ultimately death. Strategies to manage the development of edema constitute a major unmet therapeutic need. However, despite its major clinical significance, the mechanisms underlying cerebral water transport and edema formation remain elusive. Aquaporins (AQPs) are a class of water channel proteins which have been implicated in the regulation of water homeostasis and cerebral edema formation, and thus represent a promising target for alleviating stroke-induced cerebral edema. This review examines the significance of relevant AQPs in stroke injury and subsequently explores neuroprotective strategies aimed at modulating AQP expression, with a particular focus on AQP4, the most abundant AQP in the central nervous system. PMID:27438832

  9. Water channel proteins in the peripheral nervous system in health and disease.

    PubMed

    Ma, Tonghui; Gao, Hongwen; Fang, Xuedong; Yang, Hong

    2012-01-01

    The expression and function of aquaporins (AQPs) in the peripheral nervous system is a relatively under-investigated subject. Since the original description of AQP1 mRNA expression in the trigeminal ganglion in 2004, there has been significant progress in describing the expression, regulation and function of AQPs in the peripheral nervous system. Three out of the 13 mammalian AQPs (AQP1, AQP2 and AQP4) have been localized to neurons or glial cells in trigeminal ganglia, periodontal Ruffini endings, dorsal root ganglia and the enteric nervous system. Functional studies using knockout mice have suggested the involvement of AQP1 in peripheral pain perception. This review discusses current progress in this field and the possible involvement of AQPs in peripheral neuropathies.

  10. Finding NMO: The Evolving Diagnostic Criteria of Neuromyelitis Optica

    PubMed Central

    Bennett, Jeffrey L.

    2016-01-01

    Neuromyelitis optica (NMO) is an autoimmune demyelinating disorder of the central nervous system (CNS) with predilection for the optic nerves and spinal cord. Since its emergence in the medical literature in the late 1800’s, the diagnostic criteria for NMO has slowly evolved from the simultaneous presentation of neurologic and ophthalmic signs to a relapsing or monophasic CNS disorder defined by clinical, neuroimaging, and laboratory criteria. Due to the identification of a specific autoantibody response against the astrocyte water channel aquaporin-4 (AQP4) in the vast majority of affected individuals, the clinical spectrum of NMO has greatly expanded necessitating the development of new international criteria for the diagnosis of NMO spectrum disorder (NMOSD). The routine application of new diagnostic criteria for NMOSD in clinical practice will be critical for future refinement and correlation with therapeutic outcomes. PMID:27529327

  11. Ethanol-induced hyponatremia augments brain edema after traumatic brain injury.

    PubMed

    Katada, Ryuichi; Watanabe, Satoshi; Ishizaka, Atsushi; Mizuo, Keisuke; Okazaki, Shunichiro; Matsumoto, Hiroshi

    2012-04-01

    Alcohol consumption augments brain edema by expression of brain aquaporin-4 after traumatic brain injury. However, how ethanol induces brain aquaporin-4 expression remains unclear. Aquaporin-4 can operate with some of ion channels and transporters. Therefore, we hypothesized that ethanol may affect electrolytes through regulating ion channels, leading to express aquaporin-4. To clarify the hypothesis, we examined role of AQP4 expression in ethanol-induced brain edema and changes of electrolyte levels after traumatic brain injury in the rat. In the rat traumatic brain injury model, ethanol administration reduced sodium ion concentration in blood significantly 24 hr after injury. An aquaporin-4 inhibitor recovered sodium ion concentration in blood to normal. We observed low sodium ion concentration in blood and the increase of brain aquaporin-4 in cadaver with traumatic brain injury. Therefore, ethanol increases brain edema by the increase of aquaporin-4 expression with hyponatremia after traumatic brain injury.

  12. Aquaporins: important but elusive drug targets

    PubMed Central

    Verkman, Alan S.; Anderson, Marc O.; Papadopoulos, Marios C.

    2014-01-01

    The aquaporins (AQPs) are a family of small, integral membrane proteins that facilitate water transport across the plasma membranes of cells in response to osmotic gradients. Data from knockout mice support the involvement of AQPs in epithelial fluid secretion, cell migration, brain oedema and adipocyte metabolism, which suggests that modulation of AQP function or expression could have therapeutic potential in oedema, cancer, obesity, brain injury, glaucoma and several other conditions. Moreover, loss-of-function mutations in human AQPs cause congenital cataracts (AQP0) and nephrogenic diabetes insipidus (AQP2), and autoantibodies against AQP4 cause the autoimmune demyelinating disease neuromyelitis optica. Although some potential AQP modulators have been identified, challenges associated with the development of better modulators include the druggability of the target and the suitability of the assay methods used to identify modulators. PMID:24625825

  13. NMOSD triggered by yellow fever vaccination - An unusual clinical presentation with segmental painful erythema.

    PubMed

    Schöberl, F; Csanadi, E; Eren, O; Dieterich, M; Kümpfel, T

    2017-01-01

    Neuromyelitis Optica Spectrum Disorder (NMOSD) is an immune-mediated disease of the central nervous system with the presence of aquaporin 4-antibodies (AQP4-abs) in most cases. We describe a patient who developed NMOSD after a yellow fever vaccination. He presented to us with an unusual painful erythema Th7-9 triggered by touch in the respective skin area due to a cervical spinal cord lesion affecting the dorsolateral parts of C6/7. To our knowledge, this is the first case of NMOSD with such a clinical presentation expanding the clinical spectrum of NMOSD. It is important to be aware of that a yellow fever vaccination can trigger NMOSD.

  14. An update on the evidence for the efficacy and safety of rituximab in the management of neuromyelitis optica

    PubMed Central

    Collongues, Nicolas; de Seze, Jérôme

    2016-01-01

    Neuromyelitis optica spectrum disorders (NMOSDs) is a new concept which includes classical neuromyelitis optica (NMO) and partial forms of NMO such as recurrent optic neuritis with positive aquaporin-4 antibodies (AQP4) or brainstem symptoms (intractable hiccups or vomiting). This disease is clearly distinguished from multiple sclerosis (MS) and the therapeutic approach is clearly different. Rituximab is actually considered to be one of the most efficient treatments of NMOSD, even if class I studies are clearly lacking. In the present review, we describe the state of the art about rituximab treatment in NMOSD, including adults and children, plus its efficacy and tolerance and we also underline the questions that should be addressed in the near future. PMID:27134673

  15. Polyethylenimine-mediated expression of transgenes in the acinar cells of rats salivary glands in vivo

    PubMed Central

    Sramkova, Monika; Parente, Laura; Wigand, Timothy; Aye, Myo-Pale'; Shitara, Akiko; Weigert, Roberto

    2015-01-01

    Non viral-mediated transfection of plasmid DNA provides a fast and reliable way to express various transgenes in selected cell populations in live animals. Here, we show an improvement of a previously published method that is based on injecting plasmid DNA into the ductal system of the salivary glands in live rats. Specifically, using complexes between plasmid DNA and polyethyleneimine (PEI) we show that the expression of the transgenes is directed selectively to the salivary acinar cells. PEI does not affect the ability of cells to undergo regulated exocytosis, which was one of the main drawbacks of the previous methods. Moreover PEI does not affect the proper localization and targeting of transfected proteins, as shown for the apical plasma membrane water channel aquaporin 5 (AQP5). Overall, this approach, coupled with the use of intravital microscopy, permits to conduct localization and functional studies under physiological conditions, in a rapid, reliable, and affordable fashion. PMID:25621283

  16. Protein-Containing Lipid Bilayers Intercalated with Size-Matched Mesoporous Silica Thin Films.

    PubMed

    Isaksson, Simon; Watkins, Erik B; Browning, Kathryn L; Kjellerup Lind, Tania; Cárdenas, Marité; Hedfalk, Kristina; Höök, Fredrik; Andersson, Martin

    2017-01-11

    Proteins are key components in a multitude of biological processes, of which the functions carried out by transmembrane (membrane-spanning) proteins are especially demanding for investigations. This is because this class of protein needs to be incorporated into a lipid bilayer representing its native environment, and in addition, many experimental conditions also require a solid support for stabilization and analytical purposes. The solid support substrate may, however, limit the protein functionality due to protein-material interactions and a lack of physical space. We have in this work tailored the pore size and pore ordering of a mesoporous silica thin film to match the native cell-membrane arrangement of the transmembrane protein human aquaporin 4 (hAQP4). Using neutron reflectivity (NR), we provide evidence of how substrate pores host the bulky water-soluble domain of hAQP4, which is shown to extend 7.2 nm into the pores of the substrate. Complementary surface analytical tools, including quartz crystal microbalance with dissipation monitoring (QCM-D) and fluorescence microscopy, revealed successful protein-containing supported lipid bilayer (pSLB) formation on mesoporous silica substrates, whereas pSLB formation was hampered on nonporous silica. Additionally, electron microscopy (TEM and SEM), light scattering (DLS and stopped-flow), and small-angle X-ray scattering (SAXS) were employed to provide a comprehensive characterization of this novel hybrid organic-inorganic interface, the tailoring of which is likely to be generally applicable to improve the function and stability of a broad range of membrane proteins containing water-soluble domains.

  17. Effects of beta-hydroxybutyrate on brain vascular permeability in rats with traumatic brain injury.

    PubMed

    Orhan, Nurcan; Ugur Yilmaz, Canan; Ekizoglu, Oguzhan; Ahishali, Bulent; Kucuk, Mutlu; Arican, Nadir; Elmas, Imdat; Gürses, Candan; Kaya, Mehmet

    2016-01-15

    This study investigates the effect of beta-hydroxybutyrate (BHB) on blood-brain barrier (BBB) integrity during traumatic brain injury (TBI) in rats. Evans blue (EB) and horseradish peroxidase (HRP) were used as determinants of BBB permeability. Glutathione (GSH) and malondialdehyde (MDA) levels were estimated in the right (injury side) cerebral cortex of animals. The gene expression levels for occludin, glucose transporter (Glut)-1, aquaporin4 (AQP4) and nuclear factor-kappaB (NF-κB) were performed, and Glut-1 and NF-κB activities were analyzed. BHB treatment decreased GSH and MDA levels in intact animals and in those exposed to TBI (P<0.05). Glut-1 protein levels decreased in sham, BHB and TBI plus BHB groups (P<0.05). NF-κB protein levels increased in animals treated with BHB and/or exposed to TBI (P<0.05). The expression levels of occludin and AQP4 did not significantly change among experimental groups. Glut-1 expression levels increased in BHB treated and untreated animals exposed to TBI (P<0.05). While NF-κB expression levels increased in animals in TBI (P<0.01), a decrease was noticed in these animals upon BHB treatment (P<0.01). In animals exposed to TBI, EB extravasation was observed in the ipsilateral cortex regardless of BHB treatment. Ultrastructurally, BHB attenuated but did not prevent the presence of HRP in brain capillary endothelial cells of animals with TBI; moreover, the drug also led to the observation of the tracer when used in intact rats (P<0.01). Altogether, these results showed that BHB not only failed to provide overall protective effects on BBB in TBI but also led to BBB disruption in healthy animals.

  18. Seronegative Neuromyelitis Optica Spectrum Disorder following Exposure to Hepatitis B Vaccination.

    PubMed

    Heekin, Richard; Gandhy, Chetan; Robertson, Derrick

    2015-01-01

    Controversy exists regarding a potential link between exposure to recombinant hepatitis B vaccine (HBV) and central nervous system demyelinating diseases. Here, we present a case of seronegative neuromyelitis optica spectrum disorder (NMOSD) following exposure to HBV. A 28-year-old man developed painful eye movements 11 days after exposure to HBV. Within 24 h, he experienced vision loss, ascending numbness, and ataxia. T-spine MRI showed a cord lesion spanning T6-T9. Brain MRI showed bilateral optic nerve contrast enhancement and a right-sided internal capsule lesion. Cerebrospinal fluid analysis was normal, including negative oligoclonal bands and normal IgG index. AQP4-IgG serology was negative. The patient's visual symptoms improved after treatment with steroids and plasma exchange. He received plasma exchange weekly for 4 weeks with decreased numbness and tingling as well as improved coordination. Treatment with mycophenolate mofetil was started, and the patient remains clinically stable with near resolution of his prior symptoms. Neuromyelitis optica is characterized by optic neuritis and/or longitudinally extensive transverse myelitis. While our patient tested seronegative for AQP4-IgG (which remains negative in 10-50% of NMOSD cases, despite testing with the most sensitive assays available), he did meet NMOSD diagnostic criteria. In a literature review, we found 7 cases of NMOSD onset or relapse associated with exposure to various vaccines, but to our knowledge this represents the first published report of NMOSD onset following exposure to HBV. While causality between vaccination and CNS demyelinating disease remains elusive, it is important to report these cases to help develop safer vaccinations and provoke further inquiry into the pathogenesis of NMOSD.

  19. Clinical Features of Patients with Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorders

    PubMed Central

    Chen, Hai; Liu, Shi-Meng; Zhang, Xu-Xiang; Liu, Ya-Ou; Li, Si-Zhao; Liu, Zheng; Dong, Hui-Qing

    2016-01-01

    Background: Neuromyelitis optica spectrum disorder (NMOSD) was long believed to be an aggressive form of multiple sclerosis (MS). This study aimed to describe the clinical features of patients with MS and NMOSD to assist in differential diagnoses in clinical practice. Methods: Data including the patients’ serum and cerebrospinal fluid (CSF) tests, image findings, and clinical information from 175 patients with MS or NMOSD at Xuanwu Hospital, Capital Medical University from November 2012 to May 2014 were collected and analyzed retrospectively. An enzyme-linked immunosorbent assay was performed to detect the myelin oligodendrocyte glycoprotein (MOG) autoantibodies in CSF and serum. Cell-based assays were used to detect aquaporin-4-antibody (AQP4-Ab). The Chi-square test was used to compare the categorical variables. Wilcoxon rank sum test was performed to analyze the continuous variables. Results: Totally 85 MS patients (49%) and 90 NMOSD patients (51%) were enrolled, including 124 (71%) women and 51 (29%) men. Fewer MS patients (6%) had autoimmune diseases compared to NMOSD (19%) (χ2 = 6.9, P < 0.01). Patients with NMOSD had higher Expanded Disability Status Scale scores (3.5 [3]) than MS group (2 [2]) (Z = −3.69, P < 0.01). The CSF levels of white cell count and protein in both two groups were slightly elevated than the normal range, without significant difference between each other. Positivity of serum AQP4-Ab in NMOSD patients was higher than that in MS patients (MS: 0, NMOSD: 67%; χ2 = 63.9, P < 0.01). Oligoclonal bands in CSF among NMOSD patients were remarkably lower than that among MS (MS: 59%, NMOSD: 20%; χ2 = 25.7, P < 0.01). No significant difference of MOG autoantibodies was found between the two groups. Conclusion: The different CSF features combined with clinical, magnetic resonance imaging, and serum characteristics between Chinese patients with MS and NMOSD could assist in the differential diagnosis. PMID:27569235

  20. 3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) produces edema due to BBB disruption induced by MMP-9 activation in rat hippocampus.

    PubMed

    Pérez-Hernández, Mercedes; Fernández-Valle, María Encarnación; Rubio-Araiz, Ana; Vidal, Rebeca; Gutiérrez-López, María Dolores; O'Shea, Esther; Colado, María Isabel

    2017-03-16

    The recreational drug of abuse, 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) disrupts blood-brain barrier (BBB) integrity in rats through an early P2X7 receptor-mediated event which induces MMP-9 activity. Increased BBB permeability often causes plasma proteins and water to access cerebral tissue leading to vasogenic edema formation. The current study was performed to examine the effect of a single neurotoxic dose of MDMA (12.5 mg/kg, i.p.) on in vivo edema development associated with changes in the expression of the perivascular astrocytic water channel, AQP4, as well as in the expression of the tight-junction (TJ) protein, claudin-5 and Evans Blue dye extravasation in the hippocampus of adult male Dark Agouti rats. We also evaluated the ability of the MMP-9 inhibitor, SB-3CT (25 mg/kg, i.p.), to prevent these changes in order to validate the involvement of MMP-9 activation in MDMA-induced BBB disruption. The results show that MDMA produces edema of short duration temporally associated with changes in AQP4 expression and a reduction in claudin-5 expression, changes which are prevented by SB-3CT. In addition, MDMA induces a short-term increase in both tPA activity and expression, a serine-protease which is involved in BBB disruption and upregulation of MMP-9 expression. In conclusion, this study provides evidence enough to conclude that MDMA induces edema of short duration due to BBB disruption mediated by MMP-9 activation.

  1. Attenuation of Acute Phase Injury in Rat Intracranial Hemorrhage by Cerebrolysin that Inhibits Brain Edema and Inflammatory Response.

    PubMed

    Yang, Yang; Zhang, Yan; Wang, Zhaotao; Wang, Shanshan; Gao, Mou; Xu, Ruxiang; Liang, Chunyang; Zhang, Hongtian

    2016-04-01

    The outcome of intracerebral hemorrhage (ICH) is mainly determined by the volume of the hemorrhage core and the secondary brain damage to penumbral tissues due to brain swelling, microcirculation disturbance and inflammation. The present study aims to investigate the protective effects of cerebrolysin on brain edema and inhibition of the inflammation response surrounding the hematoma core in the acute stage after ICH. The ICH model was induced by administration of type VII bacterial collagenase into the stratum of adult rats, which were then randomly divided into three groups: ICH + saline; ICH + Cerebrolysin (5 ml/kg) and sham. Cerebrolysin or saline was administered intraperitoneally 1 h post surgery. Neurological scores, extent of brain edema content and Evans blue dye extravasation were recorded. The levels of pro-inflammatory factors (IL-1β, TNF-α and IL-6) were assayed by Real-time PCR and Elisa kits. Aquaporin-4 (AQP4) and tight junction proteins (TJPs; claudin-5, occludin and zonula occluden-1) expression were measured at multiple time points. The morphological and intercellular changes were characterized by Electron microscopy. It is found that cerebrolysin (5 ml/kg) improved the neurological behavior and reduced the ipsilateral brain water content and Evans blue dye extravasation. After cerebrolysin treated, the levels of pro-inflammatory factors and AQP4 in the peri-hematomal areas were markedly reduced and were accompanied with higher expression of TJPs. Electron microscopy showed the astrocytic swelling and concentrated chromatin in the ICH group and confirmed the cell junction changes. Thus, early cerebrolysin treatment ameliorates secondary injury after ICH and promotes behavioral performance during the acute phase by reducing brain edema, inflammatory response, and blood-brain barrier permeability.

  2. Evidence of Positive Selection of Aquaporins Genes from Pontoporia blainvillei during the Evolutionary Process of Cetaceans

    PubMed Central

    São Pedro, Simone Lima; Alves, João Marcelo Pereira; Barreto, André Silva; Lima, André Oliveira de Souza

    2015-01-01

    Background Marine mammals are well adapted to their hyperosmotic environment. Several morphological and physiological adaptations for water conservation and salt excretion are known to be present in cetaceans, being responsible for regulating salt balance. However, most previous studies have focused on the unique renal physiology of marine mammals, but the molecular bases of these mechanisms remain poorly explored. Many genes have been identified to be involved in osmotic regulation, including the aquaporins. Considering that aquaporin genes were potentially subject to strong selective pressure, the aim of this study was to analyze the molecular evolution of seven aquaporin genes (AQP1, AQP2, AQP3, AQP4, AQP6, AQP7, and AQP9) comparing the lineages of cetaceans and terrestrial mammals. Results Our results demonstrated strong positive selection in cetacean-specific lineages acting only in the gene for AQP2 (amino acids 23, 83, 107,179, 180, 181, 182), whereas no selection was observed in terrestrial mammalian lineages. We also analyzed the changes in the 3D structure of the aquaporin 2 protein. Signs of strong positive selection in AQP2 sites 179, 180, 181, and 182 were unexpectedly identified only in the baiji lineage, which was the only river dolphin examined in this study. Positive selection in aquaporins AQP1 (45), AQP4 (74), AQP7 (342, 343, 356) was detected in cetaceans and artiodactyls, suggesting that these events are not related to maintaining water and electrolyte homeostasis in seawater. Conclusions Our results suggest that the AQP2 gene might reflect different selective pressures in maintaining water balance in cetaceans, contributing to the passage from the terrestrial environment to the aquatic. Further studies are necessary, especially those including other freshwater dolphins, who exhibit osmoregulatory mechanisms different from those of marine cetaceans for the same essential task of maintaining serum electrolyte balance. PMID:26226365

  3. Tetramethylpyrazine-2'-O-sodium ferulate attenuates blood-brain barrier disruption and brain oedema after cerebral ischemia/reperfusion.

    PubMed

    Xu, S-H; Yin, M-S; Liu, B; Chen, M-L; He, G-W; Zhou, P-P; Cui, Y-J; Yang, D; Wu, Y-L

    2016-07-06

    Disruption of blood-brain barrier (BBB) and subsequent oedema are major causes of the pathogenesis in ischaemic stroke with which the current clinical therapy remains unsatisfied. In this study, we examined the therapeutic effect of tetramethylpyrazine-2'-O-sodium ferulate (TSF)-a novel analogue of tetramethylpyrazine in alleviating BBB breakdown and brain oedema after cerebral ischaemia/reperfusion (I/R). Then, we explored the potential mechanism of the protection on BBB disruption in cerebral I/R rat models. Male Sprague-Dawley rats (250-300 g) were subjected to 120 min middle cerebral artery occlusion (MCAO), followed by 48 h reperfusion. TSF (10.8, 18 and 30 mg kg(-1)) and ozagrel (18 mg kg(-1)) were administrated by intravenous injection immediately for the first time and then received the same dose every 24 h for 2 days. We found that TSF treatment significantly attenuated the cerebral water content, infarction volume and improved neurological outcomes in MCAO rats compared to I/R models. Moreover, we investigated the effect of TSF on the BBB for that cerebral oedema is closely related to the permeability of the BBB. We found that the permeability of BBB was improved significantly in TSF groups compared to I/R model group by Evans blue leakage testing. Furthermore, the expressions of tight junction (TJ) proteins junction adhesion molecule-1 and occludin significantly decreased, but the protein expression of matrix metalloproteinase-9 (MMP-9) and aquaporin 4 (AQP4) increased after cerebral I/R, all of which were alleviated by TSF treatment. In conclusion, TSF significantly reduced BBB permeability and brain oedema, which were correlated with regulating the expression of TJ proteins, MMP-9 and AQP4. These findings provide a novel approach to the treatment of ischaemic stroke.

  4. Rearing Light Intensity Affects Inner Retinal Pathology in a Mouse Model of X-Linked Retinoschisis but Does Not Alter Gene Therapy Outcome

    PubMed Central

    Marangoni, Dario; Yong, Zeng; Kjellström, Sten; Vijayasarathy, Camasamudram; A. Sieving, Paul; Bush, Ronald A.

    2017-01-01

    Purpose To test the effects of rearing light intensity on retinal function and morphology in the retinoschisis knockout (Rs1-KO) mouse model of X-linked retinoschisis, and whether it affects functional outcome of RS1 gene replacement. Methods Seventy-six Rs1-KO mice were reared in either cyclic low light (LL, 20 lux) or moderate light (ML, 300 lux) and analyzed at 1 and 4 months. Retinal function was assessed by electroretinogram and cavity size by optical coherence tomography. Expression of inward-rectifier K+ channel (Kir4.1), water channel aquaporin-4 (AQP4), and glial fibrillary acidic protein (GFAP) were analyzed by Western blotting. In a separate study, Rs1-KO mice reared in LL (n = 29) or ML (n = 27) received a unilateral intravitreal injection of scAAV8-hRs-IRBP at 21 days, and functional outcome was evaluated at 4 months by electroretinogram. Results At 1 month, no functional or structural differences were found between LL- or ML-reared Rs1-KO mice. At 4 months, ML-reared Rs1-KO mice showed significant reduction of b-wave amplitude and b-/a-wave ratio with no changes in a-wave, and a significant increase in cavity size, compared to LL-reared animals. Moderate light rearing increased Kir4.1 expression in Rs1-KO mice by 4 months, but not AQP4 and GFAP levels. Administration of scAAV8-hRS1-IRBP to Rs1-KO mice showed similar improvement of inner retinal ERG function independent of LL or ML rearing. Conclusions Rearing light conditions affect the development of retinal cavities and post-photoreceptor function in Rs1-KO mice. However, the effect of rearing light intensity does not interact with the efficacy of RS1 gene replacement in Rs1-KO mice. PMID:28297725

  5. The effects of hyperbaric air and hyperbaric oxygen on blood-brain barrier integrity in rats.

    PubMed

    Cevik, Nihal Gunes; Orhan, Nurcan; Yilmaz, Canan Ugur; Arican, Nadir; Ahishali, Bulent; Kucuk, Mutlu; Kaya, Mehmet; Toklu, Akin Savas

    2013-09-19

    Hyperbaric oxygen (HBO) treatment yields conflicting results on blood-brain barrier (BBB) integrity under various pathological conditions and the effects of HBO on healthy brain is poorly understood. In this experimental study, the effects of HBO on BBB integrity were investigated in comparison with hyperbaric air (HBA) in intact rats. Four sessions of HBA or HBO were applied to intact rats in 24h. BBB integrity was functionally and structurally evaluated by determining extravasation of Evans blue (EB) dye and horseradish peroxidase (HRP) tracers. In immunohistochemical evaluation, relative staining intensity for occludin, a tight junction (TJ) protein, and aquaporin 4 (AQP4), a water-channel protein, was detected in the barrier type of microvessels of brain by image analysis. BBB permeability to EB dye significantly increased in animals in HBO treatment group compared to those in HBA and control groups (p<0.05). The immunoreactivity of occludin, a tight junction protein, remained essentially unaltered in capillaries of hippocampus in all groups. In animals exposed to HBO, AQP4 immunoreactivity significantly increased in parietal cortex compared to those in HBA and control groups (p<0.01). Ultrastructurally, frequent vesicles containing HRP reaction products were observed in capillary endothelial cells in cerebral cortex and hippocampus of rats subjected to both HBA and HBO. Our results indicate that the HBO administration to intact rats increased BBB permeability to both EB and HRP while HBA increased only HRP extravasation in these animals. The results of this study suggest that HBA also impairs the BBB integrity in intact rats as well as HBO.

  6. Dynamic involvement of ATG5 in cellular stress responses

    PubMed Central

    Lin, H H; Lin, S-M; Chung, Y; Vonderfecht, S; Camden, J M; Flodby, P; Borok, Z; Limesand, K H; Mizushima, N; Ann, D K

    2014-01-01

    Autophagy maintains cell and tissue homeostasis through catabolic degradation. To better delineate the in vivo function for autophagy in adaptive responses to tissue injury, we examined the impact of compromised autophagy in mouse submandibular glands (SMGs) subjected to main excretory duct ligation. Blocking outflow from exocrine glands causes glandular atrophy by increased ductal pressure. Atg5f/−;Aqp5-Cre mice with salivary acinar-specific knockout (KO) of autophagy essential gene Atg5 were generated. While duct ligation induced autophagy and the expression of inflammatory mediators, SMGs in Atg5f/−;Aqp5-Cre mice, before ligation, already expressed higher levels of proinflammatory cytokine and Cdkn1a/p21 messages. Extended ligation period resulted in the caspase-3 activation and acinar cell death, which was delayed by Atg5 knockout. Moreover, expression of a set of senescence-associated secretory phenotype (SASP) factors was elevated in the post-ligated glands. Dysregulation of cell-cycle inhibitor CDKN1A/p21 and activation of senescence-associated β-galactosidase were detected in the stressed SMG duct cells. These senescence markers peaked at day 3 after ligation and partially resolved by day 7 in post-ligated SMGs of wild-type (WT) mice, but not in KO mice. The role of autophagy-related 5 (ATG5)-dependent autophagy in regulating the tempo, duration and magnitude of cellular stress responses in vivo was corroborated by in vitro studies using MEFs lacking ATG5 or autophagy-related 7 (ATG7) and autophagy inhibitors. Collectively, our results highlight the role of ATG5 in the dynamic regulation of ligation-induced cellular senescence and apoptosis, and suggest the involvement of autophagy resolution in salivary repair. PMID:25341032

  7. Further evidence for AQP8 expression in the myoepithelium of rat submandibular and parotid glands.

    PubMed

    Wellner, Robert B; Redman, Robert S; Swaim, William D; Baum, Bruce J

    2006-02-01

    Previously (Wellner et al., Pflugers Arch 441:49-56, 2000) we suggested that the localization of the aquaporins (AQPs) AQP5 and AQP8 in the apical and basolateral membranes of rat submandibular gland (SMG) acinar cells, respectively, provides for transcellular water flow during saliva formation. While the localization of AQP5 in this gland has been verified in several laboratories, there have been differing reports regarding AQP8 localization. Other investigators subsequently reported that AQP8 is not expressed in the acinar or ductal cells of the major salivary glands of the rat, but in the myoepithelium of each gland. Thus, we have carried out additional studies: (1) to reassess the localization of AQP8 in the rat SMG and (2) to assess the localization of AQP8 in the rat parotid gland (PG). Initially, we compared the localizations of AQP8 with recognized basolateral markers in acinar cells [the Na+,K+-ATPase and the Na+-K+-2Cl- cotransporter (NKCC1)]. Our results indicated that Na+,K+-ATPase localized in both the basal and lateral membranes of rat SMG acinar cells, whereas AQP8 was detected only in the basal regions of the acini. In the rat PG, AQP8 was invested near intercalated ducts and adjacent acini, whereas NKCC1 localized in the basolateral membranes of acinar cells. As these results were suggestive of myoepithelial localization in both glands, we compared AQP8 localization with the localization of smooth muscle actin, a myoepithelial marker. We found that AQP8 and smooth muscle actin colocalized in both the rat SMG and PG, providing additional strong support for a myoepithelial localization of AQP8. Thus, in agreement with an earlier report by other investigators (Elkjaer et al., Am J Physiol Renal Physiol 281:F1047-F1057, 2001), we report that AQP8 is expressed in the myoepithelial cells, but not in the acinar cells, of both the rat SMG and PG.

  8. Testosterone Induces Increase in Aquaporin (AQP)-1, 5, and 7 Expressions in the Uteri of Ovariectomized Rats.

    PubMed

    Salleh, Naguib; Mokhtar, Helmy Mohd; Kassim, Normadiah M; Giribabu, Nelli

    2015-12-01

    Testosterone has been reported to cause a decrease in uterine fluid volume in which this could involve the aquaporins (AQPs). This study aimed to investigate effect of testosterone on uterine AQP-1, 5, and 7 expressions in order to explain the reported reduction in uterine fluid volume under testosterone influence. Ovariectomized adult female rats received peanut oil, testosterone (1 mg/kg/day), estrogen (0.2 µg/kg/day), or combined estrogen plus testosterone for three consecutive days. Other groups received 3 days estrogen followed by 2 days either peanut oil or testosterone with or without flutamide or finasteride. A day after last injection, uteri were harvested, and the levels of AQP-1, 5, and 7 messenger RNA (mRNA) in uterine tissue homogenates were analyzed by real-time PCR (qPCR). Distributions of AQP-1, 5, and 7 proteins in uterus were observed by immunofluorescence. Levels of AQP-1 mRNA were elevated in rats receiving either estrogen or testosterone-only treatment; however, levels of AQP-5 and 7 mRNAs were elevated in rats receiving testosterone-only treatment. In rats pre-treated with estrogen, testosterone treatment resulted in higher AQP-1, 5, and 7 mRNA levels compared to vehicle treatment. Testosterone effects were antagonized by flutamide but not finasteride. Immunofluorescence study showed that AQP-1 was highly distributed in uterine lumenal epithelium following estrogen or testosterone-only treatment. However, AQP-5 and 7 distributions were high in uterine lumenal epithelium following testosterone-only treatment. Testosterone-induced up-regulation of AQP-1, 5, and 7 expressions in uterus could explain the observed reduction in uterine fluid volume as reported under this condition.

  9. Frontal white matter hyperintensities, clasmatodendrosis and gliovascular abnormalities in ageing and post-stroke dementia.

    PubMed

    Chen, Aiqing; Akinyemi, Rufus O; Hase, Yoshiki; Firbank, Michael J; Ndung'u, Michael N; Foster, Vincent; Craggs, Lucy J L; Washida, Kazuo; Okamoto, Yoko; Thomas, Alan J; Polvikoski, Tuomo M; Allan, Louise M; Oakley, Arthur E; O'Brien, John T; Horsburgh, Karen; Ihara, Masafumi; Kalaria, Raj N

    2016-01-01

    White matter hyperintensities as seen on brain T2-weighted magnetic resonance imaging are associated with varying degrees of cognitive dysfunction in stroke, cerebral small vessel disease and dementia. The pathophysiological mechanisms within the white matter accounting for cognitive dysfunction remain unclear. With the hypothesis that gliovascular interactions are impaired in subjects with high burdens of white matter hyperintensities, we performed clinicopathological studies in post-stroke survivors, who had exhibited greater frontal white matter hyperintensities volumes that predicted shorter time to dementia onset. Histopathological methods were used to identify substrates in the white matter that would distinguish post-stroke demented from post-stroke non-demented subjects. We focused on the reactive cell marker glial fibrillary acidic protein (GFAP) to study the incidence and location of clasmatodendrosis, a morphological attribute of irreversibly injured astrocytes. In contrast to normal appearing GFAP+ astrocytes, clasmatodendrocytes were swollen and had vacuolated cell bodies. Other markers such as aldehyde dehydrogenase 1 family, member L1 (ALDH1L1) showed cytoplasmic disintegration of the astrocytes. Total GFAP+ cells in both the frontal and temporal white matter were not greater in post-stroke demented versus post-stroke non-demented subjects. However, the percentage of clasmatodendrocytes was increased by >2-fold in subjects with post-stroke demented compared to post-stroke non-demented subjects (P = 0.026) and by 11-fold in older controls versus young controls (P < 0.023) in the frontal white matter. High ratios of clasmotodendrocytes to total astrocytes in the frontal white matter were consistent with lower Mini-Mental State Examination and the revised Cambridge Cognition Examination scores in post-stroke demented subjects. Double immunofluorescent staining showed aberrant co-localization of aquaporin 4 (AQP4) in retracted GFAP+ astrocytes with

  10. Frontal white matter hyperintensities, clasmatodendrosis and gliovascular abnormalities in ageing and post-stroke dementia

    PubMed Central

    Chen, Aiqing; Akinyemi, Rufus O.; Hase, Yoshiki; Firbank, Michael J.; Ndung’u, Michael N.; Foster, Vincent; Craggs, Lucy J. L.; Washida, Kazuo; Okamoto, Yoko; Thomas, Alan J.; Polvikoski, Tuomo M.; Allan, Louise M.; Oakley, Arthur E.; O’Brien, John T.; Horsburgh, Karen; Ihara, Masafumi

    2016-01-01

    White matter hyperintensities as seen on brain T2-weighted magnetic resonance imaging are associated with varying degrees of cognitive dysfunction in stroke, cerebral small vessel disease and dementia. The pathophysiological mechanisms within the white matter accounting for cognitive dysfunction remain unclear. With the hypothesis that gliovascular interactions are impaired in subjects with high burdens of white matter hyperintensities, we performed clinicopathological studies in post-stroke survivors, who had exhibited greater frontal white matter hyperintensities volumes that predicted shorter time to dementia onset. Histopathological methods were used to identify substrates in the white matter that would distinguish post-stroke demented from post-stroke non-demented subjects. We focused on the reactive cell marker glial fibrillary acidic protein (GFAP) to study the incidence and location of clasmatodendrosis, a morphological attribute of irreversibly injured astrocytes. In contrast to normal appearing GFAP+ astrocytes, clasmatodendrocytes were swollen and had vacuolated cell bodies. Other markers such as aldehyde dehydrogenase 1 family, member L1 (ALDH1L1) showed cytoplasmic disintegration of the astrocytes. Total GFAP+ cells in both the frontal and temporal white matter were not greater in post-stroke demented versus post-stroke non-demented subjects. However, the percentage of clasmatodendrocytes was increased by >2-fold in subjects with post-stroke demented compared to post-stroke non-demented subjects (P = 0.026) and by 11-fold in older controls versus young controls (P < 0.023) in the frontal white matter. High ratios of clasmotodendrocytes to total astrocytes in the frontal white matter were consistent with lower Mini-Mental State Examination and the revised Cambridge Cognition Examination scores in post-stroke demented subjects. Double immunofluorescent staining showed aberrant co-localization of aquaporin 4 (AQP4) in retracted GFAP+ astrocytes with

  11. Role of Aquaporin 0 in lens biomechanics

    SciTech Connect

    Sindhu Kumari, S.; Gupta, Neha; Shiels, Alan; FitzGerald, Paul G.; Menon, Anil G.; Mathias, Richard T.; Varadaraj, Kulandaiappan

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5{sup −/−}), AQP0 KO (heterozygous KO: AQP0{sup +/−}; homozygous KO: AQP0{sup −/−}; all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0{sup +/−} lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and

  12. Cerebrospinal fluid biomarkers of infantile congenital hydrocephalus

    PubMed Central

    Limbrick, David D.; Baksh, Brandon; Morgan, Clinton D.; Habiyaremye, Gakwaya; McAllister, James P.; Inder, Terrie E.; Mercer, Deanna; Holtzman, David M.; Strahle, Jennifer; Wallendorf, Michael J.; Morales, Diego M.

    2017-01-01

    Introduction Hydrocephalus is a complex neurological disorder with a pervasive impact on the central nervous system. Previous work has demonstrated derangements in the biochemical profile of cerebrospinal fluid (CSF) in hydrocephalus, particularly in infants and children, in whom neurodevelopment is progressing in parallel with concomitant neurological injury. The objective of this study was to examine the CSF of children with congenital hydrocephalus (CHC) to gain insight into the pathophysiology of hydrocephalus and identify candidate biomarkers of CHC with potential diagnostic and therapeutic value. Methods CSF levels of amyloid precursor protein (APP) and derivative isoforms (sAPPα, sAPPβ, Aβ42), tau, phosphorylated tau (pTau), L1CAM, NCAM-1, aquaporin 4 (AQP4), and total protein (TP) were measured by ELISA in 20 children with CHC. Two comparative groups were included: age-matched controls and children with other neurological diseases. Demographic parameters, ventricular frontal-occipital horn ratio, associated brain malformations, genetic alterations, and surgical treatments were recorded. Logistic regression analysis and receiver operating characteristic curves were used to examine the association of each CSF protein with CHC. Results CSF levels of APP, sAPPα, sAPPβ, Aβ42, tau, pTau, L1CAM, and NCAM-1 but not AQP4 or TP were increased in untreated CHC. CSF TP and normalized L1CAM levels were associated with FOR in CHC subjects, while normalized CSF tau levels were associated with FOR in control subjects. Predictive ability for CHC was strongest for sAPPα, especially in subjects ≤12 months of age (p<0.0001 and AUC = 0.99), followed by normalized sAPPβ (p = 0.0001, AUC = 0.95), tau, APP, and L1CAM. Among subjects ≤12 months, a normalized CSF sAPPα cut-point of 0.41 provided the best prediction of CHC (odds ratio = 528, sensitivity = 0.94, specificity = 0.97); these infants were 32 times more likely to have CHC. Conclusions CSF proteins such as s

  13. Real-time monitoring of changes in brain extracellular sodium and potassium concentrations and intracranial pressure after selective vasopressin-1a receptor inhibition following focal traumatic brain injury in rats.

    PubMed

    Filippidis, Aristotelis S; Liang, Xiuyin; Wang, Weili; Parveen, Shanaaz; Baumgarten, Clive M; Marmarou, Christina R

    2014-07-15

    Brain swelling and increased intracranial pressure (ICP) following traumatic brain injury (TBI) contribute to poor outcome. Vasopressin-1a receptors (V1aR) and aquaporin-4 (AQP4) regulate water transport and brain edema formation, perhaps in part by modulating cation fluxes. After focal TBI, V1aR inhibitors diminish V1aR and AQP4, reduce astrocytic swelling and brain edema. We determined whether V1aR inhibition with SR49059 after lateral controlled-cortical-impact (CCI) injury affects extracellular Na(+) and K(+) concentrations ([Na(+)]e; [K(+)]e). Ion-selective Na(+) and K(+) electrodes (ISE) and an ICP probe were implanted in rat parietal cortex, and [Na(+)]e, [K(+)]e, and physiological parameters were monitored for 5 h post-CCI. Sham-vehicle-ISE, CCI-vehicle-ISE and CCI-SR49059-ISE groups were studied, and SR49059 was administered 5 min to 5 h post-injury. We found a significant injury-induced decrease in [Na(+)]e to 80.1 ± 15 and 87.9 ± 7.9 mM and increase in [K(+)]e to 20.9 ± 3.8 and 13.4 ± 3.4 mM at 5 min post-CCI in CCI-vehicle-ISE and CCI-SR49059-ISE groups, respectively (p<0.001 vs. baseline; ns between groups). Importantly, [Na(+)]e in CCI-SR49059-ISE was reduced 5-20 min post-injury and increased to baseline at 25 min, whereas recovery in CCI-vehicle-ISE required more than 1 hr, suggesting SR49059 accelerated [Na(+)]e recovery. In contrast, [K(+)]e recovery took 45 min in both groups. Further, ICP was lower in the CCI-SR49059-ISE group. Thus, selective V1aR inhibition allowed faster [Na(+)]e recovery and reduced ICP. By augmenting the [Na(+)]e recovery rate, SR49059 may reduce trauma-induced ionic imbalance, blunting cellular water influx and edema after TBI. These findings suggest SR49059 and V1aR inhibitors are potential tools for treating cellular edema post-TBI.

  14. Neuromyelitis optica: clinical features, immunopathogenesis and treatment

    PubMed Central

    Jarius, S; Wildemann, B; Paul, F

    2014-01-01

    The term ‘neuromyelitis optica’ (‘Devic's syndrome’, NMO) refers to a syndrome characterized by optic neuritis and myelitis. In recent years, the condition has raised enormous interest among scientists and clinical neurologists, fuelled by the detection of a specific serum immunoglobulin (Ig)G reactivity (NMO-IgG) in up to 80% of patients with NMO. These autoantibodies were later shown to target aquaporin-4 (AQP4), the most abundant water channel in the central nervous system (CNS). Here we give an up-to-date overview of the clinical and paraclinical features, immunopathogenesis and treatment of NMO. We discuss the widening clinical spectrum of AQP4-related autoimmunity, the role of magnetic resonance imaging (MRI) and new diagnostic means such as optical coherence tomography in the diagnosis of NMO, the role of NMO-IgG, T cells and granulocytes in the pathophysiology of NMO, and outline prospects for new and emerging therapies for this rare, but often devastating condition. Other Articles published in this series Paraneoplastic neurological syndromes. Clinical and Experimental Immunology 2014, 175: 336–48. Disease-modifying therapy in multiple sclerosis and chronic inflammatory demyelinating polyradiculoneuropathy: common and divergent current and future strategies. Clinical and Experimental Immunology 2014, 175: 359–72. Monoclonal antibodies in treatment of multiple sclerosis. Clinical and Experimental Immunology 2014, 175: 373–84. CLIPPERS: chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids. Review of an increasingly recognized entity within the spectrum of inflammatory central nervous system disorders. Clinical and Experimental Immunology 2014, 175: 385–96. Requirement for safety monitoring for approved multiple sclerosis therapies: an overview. Clinical and Experimental Immunology 2014, 175: 397–407. Myasthenia gravis: an update for the clinician. Clinical and Experimental Immunology 2014, 175: 408

  15. Identification of new participants in the rainbow trout (Oncorhynchus mykiss) oocyte maturation and ovulation processes using cDNA microarrays

    PubMed Central

    Bobe, Julien; Montfort, Jerôme; Nguyen, Thaovi; Fostier, Alexis

    2006-01-01

    Background The hormonal control of oocyte maturation and ovulation as well as the molecular mechanisms of nuclear maturation have been thoroughly studied in fish. In contrast, the other molecular events occurring in the ovary during post-vitellogenesis have received far less attention. Methods Nylon microarrays displaying 9152 rainbow trout cDNAs were hybridized using RNA samples originating from ovarian tissue collected during late vitellogenesis, post-vitellogenesis and oocyte maturation. Differentially expressed genes were identified using a statistical analysis. A supervised clustering analysis was performed using only differentially expressed genes in order to identify gene clusters exhibiting similar expression profiles. In addition, specific genes were selected and their preovulatory ovarian expression was analyzed using real-time PCR. Results From the statistical analysis, 310 differentially expressed genes were identified. Among those genes, 90 were up-regulated at the time of oocyte maturation while 220 exhibited an opposite pattern. After clustering analysis, 90 clones belonging to 3 gene clusters exhibiting the most remarkable expression patterns were kept for further analysis. Using real-time PCR analysis, we observed a strong up-regulation of ion and water transport genes such as aquaporin 4 (aqp4) and pendrin (slc26). In addition, a dramatic up-regulation of vasotocin (avt) gene was observed. Furthermore, angiotensin-converting-enzyme 2 (ace2), coagulation factor V (cf5), adam 22, and the chemokine cxcl14 genes exhibited a sharp up-regulation at the time of oocyte maturation. Finally, ovarian aromatase (cyp19a1) exhibited a dramatic down-regulation over the post-vitellogenic period while a down-regulation of Cytidine monophosphate-N-acetylneuraminic acid hydroxylase (cmah) was observed at the time of oocyte maturation. Conclusion We showed the over or under expression of more that 300 genes, most of them being previously unstudied or unknown in the

  16. Effects of Acute Systemic Hypoxia and Hypercapnia on Brain Damage in a Rat Model of Hypoxia-Ischemia

    PubMed Central

    Zhang, Xuezhong; Wang, Nan; Tan, Jing; Fang, Xianhai; Wang, Qi; Tao, Tao; Li, Wenzhi

    2016-01-01

    Therapeutic hypercapnia has the potential for neuroprotection after global cerebral ischemia. Here we further investigated the effects of different degrees of acute systemic hypoxia in combination with hypercapnia on brain damage in a rat model of hypoxia and ischemia. Adult wistar rats underwent unilateral common carotid artery (CCA) ligation for 60 min followed by ventilation with normoxic or systemic hypoxic gas containing 11%O2,13%O2,15%O2 and 18%O2 (targeted to PaO2 30–39 mmHg, 40–49 mmHg, 50–59 mmHg, and 60–69 mmHg, respectively) or systemic hypoxic gas containing 8% carbon dioxide (targeted to PaCO2 60–80 mmHg) for 180 min. The mean artery pressure (MAP), blood gas, and cerebral blood flow (CBF) were evaluated. The cortical vascular permeability and brain edema were examined. The ipsilateral cortex damage and the percentage of hippocampal apoptotic neurons were evaluated by Nissl staining and terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate-biotin nick end labeling (TUNEL) assay as well as flow cytometry, respectively. Immunofluorescence and western blotting were performed to determine aquaporin-4 (AQP4) expression. In rats treated with severe hypoxia (PaO2 < 50 mmHg), hypercapnia augmented the decline of MAP with cortical CBF and damaged blood–brain barrier permeability (p < 0.05). In contrast, in rats treated with mild to moderate hypoxia (PaO2 > 50 mmHg), hypercapnia protected against these pathophysiological changes. Moreover, hypercapnia treatment significantly reduced brain damage in the ischemic ipsilateral cortex and decreased the percentage of apoptotic neurons in the hippocampus after the CCA ligated rats were exposed to mild or moderate hypoxemia (PaO2 > 50 mmHg); especially under mild hypoxemia (PaO2 > 60 mmHg), hypercapnia significantly attenuated the expression of AQP4 protein with brain edema (p < 0.05). Hypercapnia exerts beneficial effects under mild to moderate hypoxemia and augments detrimental

  17. Shotgun metagenomic data reveals significant abundance but low diversity of "Candidatus Scalindua" marine anammox bacteria in the Arabian Sea oxygen minimum zone.

    PubMed

    Villanueva, Laura; Speth, Daan R; van Alen, Theo; Hoischen, Alexander; Jetten, Mike S M

    2014-01-01

    Anaerobic ammonium oxidizing (anammox) bacteria are responsible for a significant portion of the loss of fixed nitrogen from the oceans, making them important players in the global nitrogen cycle. To date, marine anammox bacteria found in both water columns and sediments worldwide belong almost exclusively to "Candidatus Scalindua" species. Recently the genome assembly of a marine anammox enrichment culture dominated by "Candidatus Scalindua profunda" became available and can now be used as a template to study metagenome data obtained from various oxygen minimum zones (OMZs). Here, we sequenced genomic DNA from suspended particulate matter recovered at the upper (170 m deep) and center (600 m) area of the OMZ in the Arabian Sea by SOLiD and Ion Torrent technology. The genome of "Candidatus Scalindua profunda" served as a template to collect reads. Based on the mapped reads marine anammox Abundance was estimated to be at least 0.4% in the upper and 1.7% in the center area. Single nucleotide variation (SNV) analysis was performed to assess diversity of the "Candidatus Scalindua" populations. Most highly covered were the two diagnostic anammox genes hydrazine synthase (scal_01318c, hzsA) and hydrazine dehydrogenase (scal_03295, hdh), while other genes involved in anammox metabolism (narGH, nirS, amtB, focA, and ACS) had a lower coverage but could still be assembled and analyzed. The results show that "Candidatus Scalindua" is abundantly present in the Arabian Sea OMZ, but that the diversity within the ecosystem is relatively low.

  18. Gene function analysis in environmental isolates: The nif regulon of the strict iron oxidizing bacterium Leptospirillum ferrooxidans

    PubMed Central

    Parro, Víctor; Moreno-Paz, Mercedes

    2003-01-01

    A random genomic library from an environmental isolate of the Gram-negative bacterium Leptospirillum ferrooxidans has been printed on a microarray. Gene expression analysis was carried out with total RNA extracted from L. ferrooxidans cultures in the presence or absence of ammonium as nitrogen source under aerobic conditions. Although practically nothing is known about the genome sequence of this bacterium, this approach allowed us the selection and sequencing of only those clones bearing genes that showed an altered expression pattern. By sequence comparison, we have identified most of the genes of nitrogen fixation regulon in L. ferrooxidans, like the nifHDKENX operon, encoding the structural components of Mo-Fe nitrogenase; nifSU-hesB-hscBA-fdx operon, for Fe-S cluster assembly; the amtB gene (ammonium transporter); modA (molybdenum ABC type transporter); some regulatory genes like ntrC, nifA (the specific activator of nif genes); or two glnB-like genes (encoding the PII regulatory protein). Our results show that shotgun DNA microarrays are very powerful tools to accomplish gene expression studies with environmental bacteria whose genome sequence is still unknown, avoiding the time and effort necessary for whole genome sequencing projects. PMID:12808145

  19. The rhesus protein RhCG: a new perspective in ammonium transport and distal urinary acidification.

    PubMed

    Wagner, Carsten A; Devuyst, Olivier; Belge, Hendrica; Bourgeois, Soline; Houillier, Pascal

    2011-01-01

    Urinary acidification is a complex process requiring the coordinated action of enzymes and transport proteins and resulting in the removal of acid and the regeneration of bicarbonate. Proton secretion is mediated by luminal H(+)-ATPases and requires the parallel movement of NH₃, and its protonation to NH₄(+), to provide sufficient buffering. It has been long assumed that ammonia secretion is a passive process occurring by means of simple diffusion driven by the urinary trapping of ammonium. However, new data indicate that mammalian cells possess specific membrane proteins from the family of rhesus proteins involved in ammonia/μm permeability. Rhesus proteins were first identified in yeast and later also in plants, algae, and mammals. In rodents, RhBG and RhCG are expressed in the collecting duct, whereas in humans only RhCG was detected. Their expression increases with maturation of the kidney and accelerates after birth in parallel with other acid-base transport proteins. Deletion of RhBG in mice had no effect on renal ammonium excretion, whereas RhCG deficiency reduces renal ammonium secretion strongly, causes metabolic acidosis in acid-challenged mice, and impairs restoration of normal acid-base status. Microperfusion experiments or functional reconstitution in liposomes demonstrates that ammonia is the most likely substrate of RhCG. Similarly, crystal structures of human RhCG and the homologous bacterial AmtB protein suggest that these proteins may form gas channels.

  20. Coordination chemistry of several radius-sensitive complexones and applications to lanthanide-actinide separations

    SciTech Connect

    Potter, M.W.

    1981-10-01

    The relationships between the lanthanide complex formation equilibria and the lanthanide-actinide separation application of three radius sensitive ligands have been studied. The consecutive stepwise formation constants of the 1:1, 2:1, and 3:1 chelate species formed by the interaction of DHDMB and the tripositive lanthanides and yttrium were determined potentiometrically at 0.1 M ionic strength and 25/sup 0/C. Results indicate that three different coordination modes, one tridentate and two bidentate are in evidence. Tracer level /sup 241/Am - /sup 155/Eu cation-exchange experiments utilizing DHDMB eluents indicate that this dihydroxycarboxylate does not form a sufficiently strong americium complex to elute that actinide ahead of europium. The overall stability of the americium 3:1 complex appears intermediate between samarium and europium. Cation-exchange elutions of /sup 241/Am, /sup 155/Eu, and /sup 160/Tb mixtures with EEDTA solutions prove that the EEDTA ligand is capable of eluting americium ahead of all of the tripositive lanthanide cations. The minimum separation occurs with terbium, where the Am-Tb separation factor is 1.71. 1,5-diaminopentane-N,N,N',N'-tetraacetic acid (PMDTA) was synthesized using cation exchange. A mathematical method was developed for the formation constants of the protonated and unprotonated lanthanide-PMDTA complexes from potentiometry. Cation-exchange elutions of tracer quantities of Am, Eu, and Tb revealed that terbium is eluted ahead of both americium and europium.

  1. Borneol Is a TRPM8 Agonist that Increases Ocular Surface Wetness

    PubMed Central

    Chen, Gui-Lan; Lei, Ming; Zhou, Lu-Ping; Zou, Fangdong

    2016-01-01

    Borneol is a compound widely used in ophthalmic preparations in China. Little is known about its exact role in treating eye diseases. Here we report that transient receptor potential melastatin 8 (TRPM8) channel is a pharmacological target of borneol and mediates its therapeutic effect in the eyes. Ca2+ measurement and electrophysiological recordings revealed that borneol activated TRPM8 channel in a temperature- and dose-dependent manner, which was similar to but less effective than the action of menthol, an established TRPM8 agonist. Borneol significantly increased tear production in guinea pigs without evoking nociceptive responses at 25°C, but failed to induce tear secretion at 35°C. In contrast, menthol evoked tearing response at both 25 and 35°C. TRPM8 channel blockers N-(3-Aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)benzamide hydrochloride (AMTB) and N-(4-tert-butylphenyl)-4-(3-chloropyridin-2-yl)piperazine-1-carboxamide (BCTC) abolished borneol- and menthol-induced tear secretion. Borneol at micromolar concentrations did not affect the viability of human corneal epithelial cells. We conclude that borneol can activate the cold-sensing TRPM8 channel and modestly increase ocular surface wetness, which suggests it is an active compound in ophthalmic preparations and particularly useful in treating dry eye syndrome. PMID:27448228

  2. Nitrogen Assimilation in Escherichia coli: Putting Molecular Data into a Systems Perspective

    PubMed Central

    van Heeswijk, Wally C.; Westerhoff, Hans V.

    2013-01-01

    SUMMARY We present a comprehensive overview of the hierarchical network of intracellular processes revolving around central nitrogen metabolism in Escherichia coli. The hierarchy intertwines transport, metabolism, signaling leading to posttranslational modification, and transcription. The protein components of the network include an ammonium transporter (AmtB), a glutamine transporter (GlnHPQ), two ammonium assimilation pathways (glutamine synthetase [GS]-glutamate synthase [glutamine 2-oxoglutarate amidotransferase {GOGAT}] and glutamate dehydrogenase [GDH]), the two bifunctional enzymes adenylyl transferase/adenylyl-removing enzyme (ATase) and uridylyl transferase/uridylyl-removing enzyme (UTase), the two trimeric signal transduction proteins (GlnB and GlnK), the two-component regulatory system composed of the histidine protein kinase nitrogen regulator II (NRII) and the response nitrogen regulator I (NRI), three global transcriptional regulators called nitrogen assimilation control (Nac) protein, leucine-responsive regulatory protein (Lrp), and cyclic AMP (cAMP) receptor protein (Crp), the glutaminases, and the nitrogen-phosphotransferase system. First, the structural and molecular knowledge on these proteins is reviewed. Thereafter, the activities of the components as they engage together in transport, metabolism, signal transduction, and transcription and their regulation are discussed. Next, old and new molecular data and physiological data are put into a common perspective on integral cellular functioning, especially with the aim of resolving counterintuitive or paradoxical processes featured in nitrogen assimilation. Finally, we articulate what still remains to be discovered and what general lessons can be learned from the vast amounts of data that are available now. PMID:24296575

  3. Reduced hippocampal manganese-enhanced MRI (MEMRI) signal during pilocarpine-induced status epilepticus: edema or apoptosis?

    PubMed

    Malheiros, Jackeline Moraes; Persike, Daniele Suzete; Castro, Leticia Urbano Cardoso de; Sanches, Talita Rojas Cunha; Andrade, Lúcia da Conceição; Tannús, Alberto; Covolan, Luciene

    2014-05-01

    Manganese-enhanced MRI (MEMRI) has been considered a surrogate marker of Ca(+2) influx into activated cells and tracer of neuronal active circuits. However, the induction of status epilepticus (SE) by kainic acid does not result in hippocampal MEMRI hypersignal, in spite of its high cell activity. Similarly, short durations of status (5 or 15min) induced by pilocarpine did not alter the hippocampal MEMRI, while 30 min of SE even reduced MEMRI signal Thus, this study was designed to investigate possible explanations for the absence or decrease of MEMRI signal after short periods of SE. We analyzed hippocampal caspase-3 activation (to evaluate apoptosis), T2 relaxometry (tissue water content) and aquaporin 4 expression (water-channel protein) of rats subjected to short periods of pilocarpine-induced SE. For the time periods studied here, apoptotic cell death did not contribute to the decrease of the hippocampal MEMRI signal. However, T2 relaxation was higher in the group of animals subjected to 30min of SE than in the other SE or control groups. This result is consistent with higher AQP-4 expression during the same time period. Based on apoptosis and tissue water content analysis, the low hippocampal MEMRI signal 30min after SE can potentially be attributed to local edema rather than to cell death.

  4. Therapy of NMO spectrum disorders

    PubMed Central

    Biswas, Atanu; Mukherjee, Arabinda

    2015-01-01

    Neuromyelitis optica (NMO) is an autoimmune demyelinating condition of the central nervous system often associated with aquaporin-4 (AQP4) autoantibodies manifesting as severe optic neuritis and long segment myelitis with tendency to relapse. Seronegative patients and who do not meet the NMO criteria are classified as having NMO Spectrum Disorder (NMOSD), but are treated identically to clinically definite NMO. Acute relapse is treated with intravenous methylprednisolone for 5 days with or without subsequent treatment with plasma exchange (PE). This must be followed by oral steroid to prevent rebound worsening and further relapse. For relapse prevention, immunosuppressive agents that have been found to be effective are azathioprine, rituximab, mycophenolate mofetil, methotrexate, and mitoxantrone; although none of which have been validated in randomized, controlled trial. Some patients do relapse with monotherapy, and switching to more effective agent or use of combination therapy is beneficial in such situation. There is no consensus about the duration of preventive therapy, but generally 2-3 years of relapse-free period is considered the minimum, taking into account the risks of long-term toxicity of these agents. PMID:26538843

  5. Aquaporin-4 positive neuromyelitis optica spectrum disorders secondary to thrombopenic purpura

    PubMed Central

    Wang, Ying; Gong, Qiaoyun; Zhu, Mingqin; Lu, Chao; Sun, Li; Feng, Jiachun; Zhang, Hongliang

    2017-01-01

    Abstract Rationale: Neuromyelitis optica spectrum disorders (NMOSD) is considered as an immune-mediated disorder in the central nervous system (CNS). Numerous autoimmune diseases are frequently complicated with NMOSD and distinct clinical characteristics are noted in NMOSD patients with other autoimmune diseases. However, to our best knowledge, co-occurrence of NMOSD and thrombopenic purpura is rarely identified. Patient concerns: We presented a rare case of a 72-year-old female with 6-year history of thrombopenic purpura, and 1-month history of blurred vision as well as chest zonethesia. Anti-aquaporin-4 (AQP4) antibodies was positive in the serum of the patient. Diagnoses: With the addition of laboratory findings, iconography findings and physical examination results, the diagnosis of NMOSD was established according to the most recent diagnostic criteria. Interventions and outcomes: With the treatment of intravenous immunoglobulin (IVIg), the patient felt better at discharge without changing of expanded disability status scale (EDSS) score. Lessons: The case indicates that NMOSD could co-occur with thrombopenic purpura. The disturbance of immune system balance may explain this overlap. Further studies are warranted to reveal the mechanism and to explore whether patients with NMOSD with and without thrombopenic purpura have distinct clinical feature, drug responsiveness or prognosis. PMID:28079804

  6. Localization and trafficking of aquaporin 2 in the kidney

    PubMed Central

    Matsuzaki, Toshiyuki; Tajika, Yuki; Ablimit, Abduxukur; Hasegawa, Takahiro

    2008-01-01

    Aquaporins (AQPs) are membrane proteins serving in the transfer of water and small solutes across cellular membranes. AQPs play a variety of roles in the body such as urine formation, prevention from dehydration in covering epithelia, water handling in the blood–brain barrier, secretion, conditioning of the sensory system, cell motility and metastasis, formation of cell junctions, and fat metabolism. The kidney plays a central role in water homeostasis in the body. At least seven isoforms, namely AQP1, AQP2, AQP3, AQP4, AQP6, AQP7, and AQP11, are expressed. Among them, AQP2, the anti-diuretic hormone (ADH)-regulated water channel, plays a critical role in water reabsorption. AQP2 is expressed in principal cells of connecting tubules and collecting ducts, where it is stored in Rab11-positive storage vesicles in the basal state. Upon ADH stimulation, AQP2 is translocated to the apical plasma membrane, where it serves in the influx of water. The translocation process is regulated through the phosphorylation of AQP2 by protein kinase A. As soon as the stimulation is terminated, AQP2 is retrieved to early endosomes, and then transferred back to the Rab 11-positive storage compartment. Some AQP2 is secreted via multivesicular bodies into the urine as exosomes. Actin plays an important role in the intracellular trafficking of AQP2. Recent findings have shed light on the molecular basis that controls the trafficking of AQP2. PMID:18566824

  7. Water Transport in Aquaporins: Osmotic Permeability Matrix Analysis of Molecular Dynamics Simulations

    PubMed Central

    Hashido, Masanori; Kidera, Akinori; Ikeguchi, Mitsunori

    2007-01-01

    Single-channel osmotic water permeability (pf) is a key quantity for investigating the transport capability of the water channel protein, aquaporin. However, the direct connection between the single scalar quantity pf and the channel structure remains unclear. In this study, based on molecular dynamics simulations, we propose a pf-matrix method, in which pf is decomposed into contributions from each local region of the channel. Diagonal elements of the pf matrix are equivalent to the local permeability at each region of the channel, and off-diagonal elements represent correlated motions of water molecules in different regions. Averaging both diagonal and off-diagonal elements of the pf matrix recovers pf for the entire channel; this implies that correlated motions between distantly-separated water molecules, as well as adjacent water molecules, influence the osmotic permeability. The pf matrices from molecular dynamics simulations of five aquaporins (AQP0, AQP1, AQP4, AqpZ, and GlpF) indicated that the reduction in the water correlation across the Asn-Pro-Ala region, and the small local permeability around the ar/R region, characterize the transport efficiency of water. These structural determinants in water permeation were confirmed in molecular dynamics simulations of three mutants of AqpZ, which mimic AQP1. PMID:17449664

  8. AAV-mediated gene therapy in Dystrophin-Dp71 deficient mouse leads to blood-retinal barrier restoration and oedema reabsorption.

    PubMed

    Vacca, Ophélie; Charles-Messance, Hugo; El Mathari, Brahim; Sene, Abdoulaye; Barbe, Peggy; Fouquet, Stéphane; Aragón, Jorge; Darche, Marie; Giocanti-Aurégan, Audrey; Paques, Michel; Sahel, José-Alain; Tadayoni, Ramin; Montañez, Cecilia; Dalkara, Deniz; Rendon, Alvaro

    2016-07-15

    Dystrophin-Dp71 being a key membrane cytoskeletal protein, expressed mainly in Müller cells that provide a mechanical link at the Müller cell membrane by direct binding to actin and a transmembrane protein complex. Its absence has been related to blood-retinal barrier (BRB) permeability through delocalization and down-regulation of the AQP4 and Kir4.1 channels (1). We have previously shown that the adeno-associated virus (AAV) variant, ShH10, transduces Müller cells in the Dp71-null mouse retina efficiently and specifically (2,3). Here, we use ShH10 to restore Dp71 expression in Müller cells of Dp71 deficient mouse to study molecular and functional effects of this restoration in an adult mouse displaying retinal permeability. We show that strong and specific expression of exogenous Dp71 in Müller cells leads to correct localization of Dp71 protein restoring all protein interactions in order to re-establish a proper functional BRB and retina homeostasis thus preventing retina from oedema. This study is the basis for the development of new therapeutic strategies in dealing with diseases with BRB breakdown and macular oedema such as diabetic retinopathy (DR).

  9. Increased Circulating T Follicular Helper Cells Are Inhibited by Rituximab in Neuromyelitis Optica Spectrum Disorder.

    PubMed

    Zhao, Cong; Li, Hong-Zeng; Zhao, Dai-Di; Ma, Chao; Wu, Fang; Bai, Ya-Nan; Zhang, Min; Li, Zhu-Yi; Guo, Jun

    2017-01-01

    Neuromyelitis optica spectrum disorder (NMOSD) is a severe autoimmune disease of the central nervous system. The existence of autoantibody targeting aquaporin-4 (AQP4-Ab) indicates the involvement of humoral immunity in the pathogenesis of this disease. Rituximab (RTX), a monoclonal antibody against CD20, has been used to treat NMOSD by depleting circulating B cells and overall satisfactory outcome has been achieved. Although T follicular helper cells have been proved to regulate B cell activation and antibody production, the role of these cells in NMOSD and the impact of RTX treatment on these cells remain less understood. In this study, we found that frequencies of circulating T follicular helper (cTfh) cells and B cells together with the related cytokines, IL-21 and IL-6, were closely correlated with disease activity of NMOSD. Furthermore, B cell depletion with RTX treatment inhibited the expansion of cTfh cells, and these effects were achieved through eliminating IL-6-producing B cells and blocking the direct contact between cTfh cells and B cells. These findings imply the complicated cross talk between cTfh cells and B cells and may provide a novel therapeutic target for NMOSD.

  10. Increased Circulating T Follicular Helper Cells Are Inhibited by Rituximab in Neuromyelitis Optica Spectrum Disorder

    PubMed Central

    Zhao, Cong; Li, Hong-Zeng; Zhao, Dai-Di; Ma, Chao; Wu, Fang; Bai, Ya-Nan; Zhang, Min; Li, Zhu-Yi; Guo, Jun

    2017-01-01

    Neuromyelitis optica spectrum disorder (NMOSD) is a severe autoimmune disease of the central nervous system. The existence of autoantibody targeting aquaporin-4 (AQP4-Ab) indicates the involvement of humoral immunity in the pathogenesis of this disease. Rituximab (RTX), a monoclonal antibody against CD20, has been used to treat NMOSD by depleting circulating B cells and overall satisfactory outcome has been achieved. Although T follicular helper cells have been proved to regulate B cell activation and antibody production, the role of these cells in NMOSD and the impact of RTX treatment on these cells remain less understood. In this study, we found that frequencies of circulating T follicular helper (cTfh) cells and B cells together with the related cytokines, IL-21 and IL-6, were closely correlated with disease activity of NMOSD. Furthermore, B cell depletion with RTX treatment inhibited the expansion of cTfh cells, and these effects were achieved through eliminating IL-6-producing B cells and blocking the direct contact between cTfh cells and B cells. These findings imply the complicated cross talk between cTfh cells and B cells and may provide a novel therapeutic target for NMOSD. PMID:28360886

  11. A Nanoscale Interface Promoting Molecular and Functional Differentiation of Neural Cells

    NASA Astrophysics Data System (ADS)

    Posati, Tamara; Pistone, Assunta; Saracino, Emanuela; Formaggio, Francesco; Mola, Maria Grazia; Troni, Elisabetta; Sagnella, Anna; Nocchetti, Morena; Barbalinardo, Marianna; Valle, Francesco; Bonetti, Simone; Caprini, Marco; Nicchia, Grazia Paola; Zamboni, Roberto; Muccini, Michele; Benfenati, Valentina

    2016-08-01

    Potassium channels and aquaporins expressed by astrocytes are key players in the maintenance of cerebral homeostasis and in brain pathophysiologies. One major challenge in the study of astrocyte membrane channels in vitro, is that their expression pattern does not resemble the one observed in vivo. Nanostructured interfaces represent a significant resource to control the cellular behaviour and functionalities at micro and nanoscale as well as to generate novel and more reliable models to study astrocytes in vitro. However, the potential of nanotechnologies in the manipulation of astrocytes ion channels and aquaporins has never been previously reported. Hydrotalcite-like compounds (HTlc) are layered materials with increasing potential as biocompatible nanoscale interface. Here, we evaluate the effect of the interaction of HTlc nanoparticles films with primary rat neocortical astrocytes. We show that HTlc films are biocompatible and do not promote gliotic reaction, while favouring astrocytes differentiation by induction of F-actin fibre alignment and vinculin polarization. Western Blot, Immunofluorescence and patch-clamp revealed that differentiation was accompanied by molecular and functional up-regulation of both inward rectifying potassium channel Kir 4.1 and aquaporin 4, AQP4. The reported results pave the way to engineering novel in vitro models to study astrocytes in a in vivo like condition.

  12. Molecular contributions to neurovascular unit dysfunctions after brain injuries: lessons for target-specific drug development

    PubMed Central

    Jullienne, Amandine; Badaut, Jérôme

    2014-01-01

    The revised ‘expanded’ neurovascular unit (eNVU) is a physiological and functional unit encompassing endothelial cells, pericytes, smooth muscle cells, astrocytes and neurons. Ischemic stroke and traumatic brain injury are acute brain injuries directly affecting the eNVU with secondary damage, such as blood–brain barrier (BBB) disruption, edema formation and hypoperfusion. BBB dysfunctions are observed at an early postinjury time point, and are associated with eNVU activation of proteases, such as tissue plasminogen activator and matrix metalloproteinases. BBB opening is accompanied by edema formation using astrocytic AQP4 as a key protein regulating water movement. Finally, nitric oxide dysfunction plays a dual role in association with BBB injury and dysregulation of cerebral blood flow. These mechanisms are discussed including all targets of eNVU encompassing endothelium, glial cells and neurons, as well as larger blood vessels with smooth muscle. In fact, the feeding blood vessels should also be considered to treat stroke and traumatic brain injury. This review underlines the importance of the eNVU in drug development aimed at improving clinical outcome after stroke and traumatic brain injury. PMID:24489483

  13. Expression, Distribution and Role of Aquaporin Water Channels in Human and Animal Stomach and Intestines.

    PubMed

    Zhu, Cui; Chen, Zhuang; Jiang, Zongyong

    2016-08-29

    Stomach and intestines are involved in the secretion of gastrointestinal fluids and the absorption of nutrients and fluids, which ensure normal gut functions. Aquaporin water channels (AQPs) represent a major transcellular route for water transport in the gastrointestinal tract. Until now, at least 11 AQPs (AQP1-11) have been found to be present in the stomach, small and large intestines. These AQPs are distributed in different cell types in the stomach and intestines, including gastric epithelial cells, gastric glands cells, absorptive epithelial cells (enterocytes), goblet cells and Paneth cells. AQP1 is abundantly distributed in the endothelial cells of the gastrointestinal tract. AQP3 and AQP4 are mainly distributed in the basolateral membrane of epithelial cells in the stomach and intestines. AQP7, AQP8, AQP10 and AQP11 are distributed in the apical of enterocytes in the small and large intestines. Although AQP-null mice displayed almost no phenotypes in gastrointestinal tracts, the alterations of the expression and localization of these AQPs have been shown to be associated with the pathology of gastrointestinal disorders, which suggests that AQPs play important roles serving as potential therapeutic targets. Therefore, this review provides an overview of the expression, localization and distribution of AQPs in the stomach, small and large intestine of human and animals. Furthermore, this review emphasizes the potential roles of AQPs in the physiology and pathophysiology of stomach and intestines.

  14. Aquaporin water channels in the canine gubernaculum testis.

    PubMed

    Arrighi, Silvana; Aralla, Marina; Fracassetti, Paola; Mobasheri, Ali; Cremonesi, Fausto

    2013-07-01

    The jelly-like gubernaculum testis (GT) is a hydrated structure consisting of a concentric sheath of dense connective tissue around a loose mesenchymal core, with two cords of skeletal muscle cells asymmetrically placed alongside. Expansion of the GT occurs during the transabdominal phase of testicular descent, linked to cell proliferation together with modifications of the hydric content of the organ. The aim of this study was to detect immunohistochemically the presence of aquaporins (AQPs), integral membrane proteins permitting passive transcellular water movement, in the canine GTs. Samples (n=15) were obtained from pregnancies of 9 medium sized bitches and dissected from healthy fetuses. Five fetuses were aged 35-45 days of gestation, 10 fetuses from 46 days of gestation to delivery, thus offering us the opportunity to study the progressive maturation of the gubernacula. The presence of AQP3, 4, 7, 8 and -9 was assessed in the muscular components of the GT, some of them (AQP3, AQP4, AQP7) with increasing intensity through the second half of pregnancy up to term. AQP1 was localized in the capillary and venous endothelia in the younger fetuses, also in the artery adventitia and in the nerve perineurium in progressively older fetuses. These data demonstrate the potential importance and contribution of AQP-mediated water flux in hydration and volume modification of the growing GT in a canine model.

  15. 5-Fluorouracil induces diarrhea with changes in the expression of inflammatory cytokines and aquaporins in mouse intestines.

    PubMed

    Sakai, Hiroyasu; Sagara, Atsunobu; Matsumoto, Kenjiro; Hasegawa, Satoshi; Sato, Ken; Nishizaki, Maiko; Shoji, Tetsuro; Horie, Syunji; Nakagawa, Takayuki; Tokuyama, Shogo; Narita, Minoru

    2013-01-01

    Although the mechanisms of 5-fluorouracil (5-FU)-induced diarrhea remain unclear, accumulating evidence has indicated that changes in the mucosal immune system and aquaporins (AQPs) may play a role in its pathogenesis. Therefore, we investigated the possible changes in the gene expression of inflammatory cytokines and AQPs in the intestines of mice with 5-FU-induced diarrhea. In the present study, the expressions of mRNAs that encode inflammatory cytokines, TNF-α, IL-1β, IL-6, Il-17A and IL-22, were significantly increased throughout the entire colon of mice that exhibited diarrhea following 5-FU administration. In contrast, the gene expression of IFNγ was upregulated only in the distal colon. These increases were significantly reduced by the administration of etanercept. However, 5-FU-induced diarrhea was not recovered by etanercept. On the other hand, the genes for AQPs 4 and 8 were markedly present in the colon, and these expressions in the intestines were significantly decreased by treatment with 5-FU. These decreases were not reversed by etanercept. These findings suggest TNF-α neutralization had no effect on the acutely 5-FU-induced diarrhea and impaired AQPs but reduced dramatically several inflammatory cytokines.

  16. Chronic cocaine administration causes extensive white matter damage in brain: diffusion tensor imaging and immunohistochemistry studies.

    PubMed

    Narayana, Ponnada A; Herrera, Juan J; Bockhorst, Kurt H; Esparza-Coss, Emilio; Xia, Ying; Steinberg, Joel L; Moeller, F Gerard

    2014-03-30

    The effect of chronic cocaine exposure on multiple white matter structures in rodent brain was examined using diffusion tensor imaging (DTI), locomotor behavior, and end point histology. The animals received either cocaine at a dose of 100mg/kg (N=19), or saline (N=17) for 28 days through an implanted osmotic minipump. The animals underwent serial DTI scans, locomotor assessment, and end point histology for determining the expressions of myelin basic protein (MBP), neurofilament-heavy protein (NF-H), proteolipid protein (PLP), Nogo-A, aquaporin-4 (AQP-4), and growth associated protein-43 (GAP-43). Differences in the DTI measures were observed in the splenium (scc) and genu (gcc) of the corpus callosum (cc), fimbria (fi), and the internal capsule (ic). A significant increase in the activity in the fine motor movements and a significant decrease in the number of rearing events were observed in the cocaine-treated animals. Reduced MBP and Nogo-A and increased GAP-43 expressions were most consistently observed in these structures. A decrease in the NF-H expression was observed in fi and ic. The reduced expression of Nogo-A and the increased expression of GAP-43 may suggest destabilization of axonal connectivity and increased neurite growth with aberrant connections. Increased GAP-43 suggests drug-induced plasticity or a possible repair mechanism response. The findings indicated that multiple white matter tracts are affected following chronic cocaine exposure.

  17. The role of pericytic laminin in blood brain barrier integrity maintenance

    PubMed Central

    Gautam, Jyoti; Zhang, Xuanming; Yao, Yao

    2016-01-01

    Laminin, a major component of the basement membrane, plays an important role in blood brain barrier regulation. At the neurovascular unit, brain endothelial cells, astrocytes, and pericytes synthesize and deposit different laminin isoforms into the basement membrane. It has been shown that laminin α4 (endothelial laminin) regulates vascular integrity at embryonic/neonatal stage, while astrocytic laminin maintains vascular integrity in adulthood. Here, we investigate the function of pericyte-derived laminin in vascular integrity. Using a conditional knockout mouse line, we report that loss of pericytic laminin leads to hydrocephalus and BBB breakdown in a small percentage (10.7%) of the mutants. Interestingly, BBB disruption always goes hand-in-hand with hydrocephalus in these mutants, and neither symptom is observed in the rest 89.3% of the mutants. Further mechanistic studies show that reduced tight junction proteins, diminished AQP4 expression, and decreased pericyte coverage are responsible for the BBB disruption. Together, these data suggest that pericyte-derived laminin is involved in the maintenance of BBB integrity and regulation of ventricular size/development. PMID:27808256

  18. A Nanoscale Interface Promoting Molecular and Functional Differentiation of Neural Cells

    PubMed Central

    Posati, Tamara; Pistone, Assunta; Saracino, Emanuela; Formaggio, Francesco; Mola, Maria Grazia; Troni, Elisabetta; Sagnella, Anna; Nocchetti, Morena; Barbalinardo, Marianna; Valle, Francesco; Bonetti, Simone; Caprini, Marco; Nicchia, Grazia Paola; Zamboni, Roberto; Muccini, Michele; Benfenati, Valentina

    2016-01-01

    Potassium channels and aquaporins expressed by astrocytes are key players in the maintenance of cerebral homeostasis and in brain pathophysiologies. One major challenge in the study of astrocyte membrane channels in vitro, is that their expression pattern does not resemble the one observed in vivo. Nanostructured interfaces represent a significant resource to control the cellular behaviour and functionalities at micro and nanoscale as well as to generate novel and more reliable models to study astrocytes in vitro. However, the potential of nanotechnologies in the manipulation of astrocytes ion channels and aquaporins has never been previously reported. Hydrotalcite-like compounds (HTlc) are layered materials with increasing potential as biocompatible nanoscale interface. Here, we evaluate the effect of the interaction of HTlc nanoparticles films with primary rat neocortical astrocytes. We show that HTlc films are biocompatible and do not promote gliotic reaction, while favouring astrocytes differentiation by induction of F-actin fibre alignment and vinculin polarization. Western Blot, Immunofluorescence and patch-clamp revealed that differentiation was accompanied by molecular and functional up-regulation of both inward rectifying potassium channel Kir 4.1 and aquaporin 4, AQP4. The reported results pave the way to engineering novel in vitro models to study astrocytes in a in vivo like condition. PMID:27503424

  19. Central Role of Maladapted Astrocytic Plasticity in Ischemic Brain Edema Formation

    PubMed Central

    Wang, Yu-Feng; Parpura, Vladimir

    2016-01-01

    Brain edema formation and the ensuing brain damages are the major cause of high mortality and long term disability following the occurrence of ischemic stroke. In this process, oxygen and glucose deprivation and the resulting reperfusion injury play primary roles. In response to the ischemic insult, the neurovascular unit experiences both intracellular and extracellular edemas, associated with maladapted astrocytic plasticity. The astrocytic plasticity includes both morphological and functional plasticity. The former involves a reactive gliosis and the subsequent glial retraction. It relates to the capacity of astrocytes to buffer changes in extracellular chemical levels, particularly K+ and glutamate, as well as the integrity of the blood-brain barrier (BBB). The latter involves the expression and activity of a series of ion and water transport proteins. These molecules are grouped together around glial fibrillary acidic protein (GFAP) and water channel protein aquaporin 4 (AQP4) to form functional networks, regulate hydromineral balance across cell membranes and maintain the integrity of the BBB. Intense ischemic challenges can disrupt these capacities of astrocytes and result in their maladaptation. The maladapted astrocytic plasticity in ischemic stroke cannot only disrupt the hydromineral homeostasis across astrocyte membrane and the BBB, but also leads to disorders of the whole neurovascular unit. This review focuses on how the maladapted astrocytic plasticity in ischemic stroke plays the central role in the brain edema formation. PMID:27242440

  20. Desformylgramicidin: a model channel with an extremely high water permeability.

    PubMed Central

    Saparov, S M; Antonenko, Y N; Koeppe, R E; Pohl, P

    2000-01-01

    The water conductivity of desformylgramicidin exceeds the permeability of gramicidin A by two orders of magnitude. With respect to its single channel hydraulic permeability coefficient of 1.1.10(-12) cm(3) s(-1), desformylgramicidin may serve as a model for extremely permeable aquaporin water channel proteins (AQP4 and AQPZ). This osmotic permeability exceeds the conductivity that is predicted by the theory of single-file transport. It was derived from the concentration distributions of both pore-impermeable and -permeable cations that were simultaneously measured by double barreled microelectrodes in the immediate vicinity of a planar bilayer. From solvent drag experiments, approximately five water molecules were found to be transported by a single-file process along with one ion through the channel. The single channel proton, potassium, and sodium conductivities were determined to be equal to 17 pS (pH 2.5), 7 and 3 pS, respectively. Under any conditions, the desformyl-channel remains at least 10 times longer in its open state than gramicidin A. PMID:11053127

  1. [Anti-amphiphysin antibody-positive paraneoplastic neurological syndrome with a longitudinally extensive spinal cord lesion of the dorsal column].

    PubMed

    Neshige, Shuichiro; Hara, Naoyuki; Takeshima, Shinichi; Iwaki, Hirotaka; Shimoe, Yutaka; Takamatsu, Kazuhiro; Kuriyama, Masaru

    2014-01-01

    A 53-year-old woman was admitted to our hospital because of gait disturbance and paresthesia of the lower extremities. She also had marked deep sense impairment in her lower limbs. Cervical MRI showed a longitudinally extensive spinal cord lesion of the dorsal column at levels C1-T11. The findings of cerebrospinal fluid examination, including the IgG index (0.65), were normal. Serum anti-AQP4 antibody was negative, but anti-amphiphysin antibody was positive. Electrophysiological examinations suggested the presence of lesions in the dorsal column of the spinal cord and dorsal root ganglion (DRG). Enlargement of and fluorodeoxyglucose accumulation in her left parasternal lymph node was observed on contrast-enhanced CT and PET-CT, respectively. The lymph node biopsy was underwent by using thoracoscopy. The metastasis of carcinoma was pathologically confirmed. Although the primary tumor was not detected on PET-CT re-examination, immunostaining of the biopsied lymph node specimen was positive for both the progesterone receptor and estrogen receptor. On the basis of these findings, the patient was diagnosed with paraneoplastic neurological syndrome due to potential breast cancer. The disorder is an immunological subacute sensory neuropathy with a longitudinally extensive spinal cord lesion of the dorsal column and a DRG lesion.

    </