Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Molecular characterization and expression of urotensin II and its receptor in the flounder (Platichthys flesus)
T2 - a hormone system supporting body fluid homeostasis in euryhaline fish
AU - Lu, Weiqun
AU - Greenwood, Michael
AU - Dow, Louise
AU - Yuill, Janette
AU - Worthington, John
AU - Brierley, Matthew J
AU - McCrohan, Catherine R
AU - Riccardi, Daniela
AU - Balment, Richard J
PY - 2006/8
Y1 - 2006/8
N2 - Urotensin II (UII) is a potent vasoconstrictor in mammals, but the source of circulating UII remains unclear. Investigations of the caudal neurosecretory system (CNSS), considered the major source of UII in fish, alongside target tissue expression of UII receptor (UT), can provide valuable insights into this highly conserved regulatory system. We report UII gene characterization, expression of the first fish UT, and responses to salinity challenge in flounder. The 12-aa UII peptide shares 73% sequence identity with pig and human UII. Flounder UT receptor shares 56.7% identity with rat. Although the CNSS is the major site of UII expression, RT-PCR revealed expression of UII and UT in all tissues tested. Around 30-40% of large CNSS Dahlgren cells expressed UII, alone or in combination with urotensin I and/or corticotrophin releasing hormone. Immunolocalization of UT in osmoregulatory tissues (gill, kidney) was associated with vascular elements. There were no consistent differences in CNSS UII expression or plasma UII between seawater (SW)- and freshwater (FW)-adapted fish, although gill and kidney UT expression was lower in FW animals. After acute transfer from SW to FW, plasma UII and kidney and gill UT expression were reduced, whereas UT expression in kidney was increased after reverse transfer. UII appears to be more important to combat dehydration and salt-loading in SW than the hemodilution faced in FW. Potentially, altered target tissue sensitivity through changes in UT expression, is an important physiological controlling mechanism, not only relevant for migratory fish but also likely conserved in mammals.
AB - Urotensin II (UII) is a potent vasoconstrictor in mammals, but the source of circulating UII remains unclear. Investigations of the caudal neurosecretory system (CNSS), considered the major source of UII in fish, alongside target tissue expression of UII receptor (UT), can provide valuable insights into this highly conserved regulatory system. We report UII gene characterization, expression of the first fish UT, and responses to salinity challenge in flounder. The 12-aa UII peptide shares 73% sequence identity with pig and human UII. Flounder UT receptor shares 56.7% identity with rat. Although the CNSS is the major site of UII expression, RT-PCR revealed expression of UII and UT in all tissues tested. Around 30-40% of large CNSS Dahlgren cells expressed UII, alone or in combination with urotensin I and/or corticotrophin releasing hormone. Immunolocalization of UT in osmoregulatory tissues (gill, kidney) was associated with vascular elements. There were no consistent differences in CNSS UII expression or plasma UII between seawater (SW)- and freshwater (FW)-adapted fish, although gill and kidney UT expression was lower in FW animals. After acute transfer from SW to FW, plasma UII and kidney and gill UT expression were reduced, whereas UT expression in kidney was increased after reverse transfer. UII appears to be more important to combat dehydration and salt-loading in SW than the hemodilution faced in FW. Potentially, altered target tissue sensitivity through changes in UT expression, is an important physiological controlling mechanism, not only relevant for migratory fish but also likely conserved in mammals.
KW - Adaptation, Physiological
KW - Amino Acid Sequence
KW - Animals
KW - Base Sequence
KW - Body Fluids
KW - Flounder
KW - Fresh Water
KW - Gene Expression Regulation
KW - Gene Library
KW - Gills
KW - Homeostasis
KW - Immunohistochemistry
KW - Kidney
KW - Molecular Sequence Data
KW - Pituitary Gland
KW - Receptors, G-Protein-Coupled
KW - Reverse Transcriptase Polymerase Chain Reaction
KW - Seawater
KW - Spinal Cord
KW - Urotensins
KW - Water-Electrolyte Balance
U2 - 10.1210/en.2005-1457
DO - 10.1210/en.2005-1457
M3 - Journal article
C2 - 16675528
VL - 147
SP - 3692
EP - 3708
JO - Clinical Endocrinology
JF - Clinical Endocrinology
SN - 0013-7227
IS - 8
ER -