title: A Systematic Characterization of Aquaporin-9 Expression in Human Normal and Pathological Tissues.
abstract: AQP9 is known to facilitate hepatocyte glycerol uptake. Murine AQP9 protein expression has been verified in liver, skin, epididymis, epidermis and neuronal cells using knockout mice. Further expression sites have been reported in humans. We aimed to verify AQP9 expression in a large set of human normal organs, different cancer types, rheumatoid arthritis synovial biopsies as well as in cell lines and primary cells. Combining standardized immunohistochemistry with high-throughput mRNA sequencing, we found that AQP9 expression in normal tissues was limited, with high membranous expression only in hepatocytes. In cancer tissues, AQP9 expression was mainly found in hepatocellular carcinomas, suggesting no general contribution of AQP9 to carcinogenesis. AQP9 expression in a subset of rheumatoid arthritis synovial tissue samples was affected by Humira, thereby supporting a suggested role of TNFα in AQP9 regulation in this disease. Among cell lines and primary cells, LP-1 myeloma cells expressed high levels of AQP9, whereas low expression was observed in a few other lymphoid cell lines. AQP9 mRNA and protein expression was absent in HepG2 hepatocellular carcinoma cells. Overall, AQP9 expression in human tissues appears to be more selective than in mice.
authors.affiliation: Science for Life Laboratory, Department of Immunology Genetics and Pathology, Uppsala University, Uppsala, Sweden (CL, AA)
authors.forename: Cecilia
authors.initials: C
authors.lastname: Lindskog
authors.affiliation: Science for Life Laboratory, Department of Immunology Genetics and Pathology, Uppsala University, Uppsala, Sweden (CL, AA)
authors.forename: Anna
authors.initials: A
authors.lastname: Asplund
authors.affiliation: Rheumatology Clinic, Department of Medicine, Karolinska Institutet at Karolinska University Hospital, Stockholm, Sweden (AC)
authors.forename: Anca
authors.initials: A
authors.lastname: Catrina
authors.affiliation: Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden (SN, MR)
authors.forename: Søren
authors.initials: S
authors.lastname: Nielsen
authors.affiliation: Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden (SN, MR)|Institute for Health Science and Technology, Aalborg University, Aalborg Ø, Denmark (MR)
authors.forename: Michael
authors.initials: M
authors.lastname: Rützler
mesh_terms: D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D009928:Organ Specificity; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: C109669:AQP9 protein, human; D020346:Aquaporins; D012333:RNA, Messenger
keywords: HepG2; Humira; LP-1; TNF-alpha; aquaporin