title: Angiotensin AT2 receptor activates the cyclic-AMP signaling pathway in eel.
abstract: A unique angiotensin type 2 receptor (AT2) that induces a cAMP signaling pathway was cloned and characterized for the first time in fish, Anguilla japonica. Phylogeny and synteny results showed that the AT2s among fishes and tetrapods share the same origin despite a sub-cluster formation among eel, salmon, and zebrafish. The eel AT2 was expressed abundantly in the spleen and localized at straight arterioles and ellipsoid regions prior to the sinusoid, suggesting a role in the regulation of microcirculation and/or immune response. Various angiotensin (Ang) peptides, including Ang II, Ang III, and Ang IV, were detected in the spleen by a radioimmunoassay coupled with HPLC separation, and these endogenous peptides stimulated a cAMP signaling, which has no crosstalk with cGMP pathway. The common and contrasting features of AT2 between fishes and mammals imply some ancestral characters of AT2, which are important information for receptor binding and evolutionary studies.
authors.affiliation: Laboratory of Physiology, Department of Marine Biosciences, Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8564, Japan. martywong@aori.u-tokyo.ac.jp
authors.forename: Marty Kwok-Shing
authors.initials: MK
authors.lastname: Wong
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takei
mesh_terms: D000595:Amino Acid Sequence; D000809:Angiotensins / Q000378:metabolism; D000811:Anguilla; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D015870:Gene Expression; D005880:Gills / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044139:Receptor, Angiotensin, Type 2 / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D015290:Second Messenger Systems; D013154:Spleen / Q000378:metabolism; D026801:Synteny
chemical_list: D000809:Angiotensins; D029941:Fish Proteins; D012333:RNA, Messenger; D044139:Receptor, Angiotensin, Type 2; D000242:Cyclic AMP