title: Increased expression of cyclooxygenase-2 in the renal cortex of human prorenin receptor gene-transgenic rats.
abstract: Increased macula densa cyclooxygenase-2 (COX-2) is observed in diabetic rats and may contribute to hyperfiltration states. However, the signals mediating increased COX-2 expression in diabetic rats remain undetermined. We recently found that non-proteolytic activation of prorenin by site-specific binding proteins, such as prorenin receptor, plays a pivotal role in the development of diabetic nephropathy. The present study was designed to determine the contribution of prorenin receptor to renal cortical COX-2 expression. The COX-2 mRNA and protein levels of six 4-week-old male wild-type rats and six human prorenin receptor gene-transgenic (hProRenRcTg) rats were measured by real-time polymerase chain reaction methods, Western blotting, and immunohistochemistry, and compared. There were no differences between the two groups in arterial pressure measured by telemetry, urinary sodium excretion, or renal levels of rat prorenin receptor mRNA. The renal cortical COX-2 mRNA levels of the hProRenRcTg rats were significantly higher than those of the wild-type rats, and the renal cortical COX-2 protein levels were also higher in hProRenRcTg rats than in the wild-type rats. Immunohistochemical analysis revealed that COX-2 immunostaining was predominantly present in the macula densa cells, and significantly more COX-2-positive cells were present in the hProRenRcTg rats than in the wild-type rats. In addition, COX-2 inhibition with NS398 significantly decreased renal cortical blood flow in the hProRenRcTg rats but not in the wild-type rats. These results strongly suggest that human prorenin receptor directly or indirectly contributes to the regulation of renal cortical COX-2 expression.
authors.affiliation: Department of Internal Medicine, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kaneshiro
authors.forename: A
authors.initials: A
authors.lastname: Ichihara
authors.forename: T
authors.initials: T
authors.lastname: Takemitsu
authors.forename: M
authors.initials: M
authors.lastname: Sakoda
authors.forename: F
authors.initials: F
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Nakagawa
authors.forename: M
authors.initials: M
authors.lastname: Hayashi
authors.forename: T
authors.initials: T
authors.lastname: Inagami
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006801:Humans; D007668:Kidney / Q000098:blood supply / Q000378:metabolism; D007672:Kidney Cortex / Q000098:blood supply / Q000378:metabolism*; D008833:Microcirculation / Q000502:physiology; D010766:Phosphorylation; D051381:Rats; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism*; D012039:Regional Blood Flow / Q000502:physiology; D000093342:Prorenin Receptor
chemical_list: D011956:Receptors, Cell Surface; D051546:Cyclooxygenase 2; D048049:Extracellular Signal-Regulated MAP Kinases; D000093342:Prorenin Receptor