title: Urotensin II receptor (UTR) exists in hyaline chondrocytes: a study of peripheral distribution of UTR in the African clawed frog, Xenopus laevis.
abstract: Urotensin II (UII) and UII-related peptide (URP) exhibit diverse physiological actions including vasoconstriction, locomotor activity, osmoregulation, and immune response through UII receptor (UTR), which is expressed in the central nervous system and peripheral tissues of fish and mammals. In amphibians, only UII has been identified. As the first step toward elucidating the actions of UII and URP in amphibians, we cloned and characterized URP and UTR from the African clawed frog Xenopus laevis. Functional analysis showed that treatment of UII or URP with Chinese hamster ovary cells transfected with the cloned receptor increased the intracellular calcium concentration in a concentration-dependent manner, whereas the administration of the UTR antagonist urantide inhibited UII- or URP-induced Ca(2+) mobilization. An immunohistochemical study showed that UTR was expressed in the splenocytes and leukocytes isolated from peripheral blood, suggesting that UII and URP are involved in the regulation of the immune system. UTR was also localized in the apical membrane of the distal tubule of the kidney and in the transitional epithelial cells of the urinary bladder. This result supports the view that the UII/URP-UTR system plays an important role in osmoregulation of amphibians. Interestingly, immunopositive labeling for UTR was first detected in the chondrocytes of various hyaline cartilages (the lung septa, interphalangeal joint and sternum). The expression of UTR was also observed in the costal cartilage, tracheal cartilages, and xiphoid process of the rat. These novel findings probably suggest that UII and URP mediate the formation of the cartilaginous matrix.
authors: Department of Biological Science, Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan. nkonno@sci.u-toyama.ac.jp
authors: Norifumi
authors: N
authors: Konno
authors: Yuya
authors: Y
authors: Fujii
authors: Haruka
authors: H
authors: Imae
authors: Hiroyuki
authors: H
authors: Kaiya
authors: Takao
authors: T
authors: Mukuda
authors: Mikiya
authors: M
authors: Miyazato
authors: Kouhei
authors: K
authors: Matsuda
authors: Minoru
authors: M
authors: Uchiyama
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002356:Cartilage / Q000378:metabolism; D019902:Chondrocytes / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D006818:Hyalin / Q000378:metabolism; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology; D036361:Peptide Hormones / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016415:Sequence Alignment; D014018:Tissue Distribution; D014579:Urotensins / Q000378:metabolism* / Q000494:pharmacology; D014982:Xenopus laevis / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D036361:Peptide Hormones; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D014579:Urotensins; C492079:urotensin II (4-11), Pen(5)-Trp(7)-Orn(8)-; C029677:urotensin II; D002118:Calcium