title: Unaltered Glutamate Transporter-1 Protein Levels in Aquaporin-4 Knockout Mice.
abstract: 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.
authors.affiliation: 1 Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, University of California, Riverside, CA, USA.
authors.forename: Jacqueline A
authors.initials: JA
authors.lastname: Hubbard
authors.affiliation: 1 Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, University of California, Riverside, CA, USA.
authors.forename: Devin K
authors.initials: DK
authors.lastname: Binder
mesh_terms: D000818:Animals; D051401:Aquaporin 4 / Q000172:deficiency* / Q000235:genetics; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D027342:Excitatory Amino Acid Transporter 2 / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics*; D047468:Immunoprecipitation; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013045:Species Specificity
chemical_list: D051401:Aquaporin 4; D027342:Excitatory Amino Acid Transporter 2
keywords: EAAT2; coimmunoprecipitation; colocalize; physical interaction