Stanniocalcin in the seawater salmon: structure, function, and regulation

Stanniocalcin (STC) is a homodimeric glycoprotein hormone that was first discovered in fish, where it is produced by unique endocrine glands known as the corpuscles of Stannius (CS). In freshwater salmon, STC plays an integral role in Ca and phosphate homeostasis. High levels of extracellular Ca pro...

Full description

Saved in:
Bibliographic Details
Published in:American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 1998-04, Vol.274 (4), p.R1177
Main Authors: Wagner, Graham F, Jaworski, Ewa M, Haddad, Michel
Format: Article
Language:English
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Stanniocalcin (STC) is a homodimeric glycoprotein hormone that was first discovered in fish, where it is produced by unique endocrine glands known as the corpuscles of Stannius (CS). In freshwater salmon, STC plays an integral role in Ca and phosphate homeostasis. High levels of extracellular Ca promote the synthesis and release of STC, which on entering the bloodstream reduces the levels of gill and gut Ca transport and renal phosphate excretion to restore normocalcemia. In this report, we have examined STC in seawater salmon. We have studied the distribution of STC protein and mRNA in marine Atlantic salmon CS cells, the responsiveness of these cells to Ca , and some physical properties of the hormone. Our results demonstrated that all Atlantic salmon CS cells expressed the STC gene. Furthermore, these cells exhibited a Ca sensitivity that was remarkably similar to those in freshwater salmon in terms of its ability to stimulate STC secretion and gene expression. When Atlantic salmon glands were fractionated by concanavalin A (ConA)-Sepharose chromatography, two distinct forms of the hormone were identified, both of which were recognized by sockeye salmon STC antiserum, and designated as STC1 and STC2. STC1 was a glycosylated, 42-kDa disulfide-linked dimer, with a high affinity for ConA. STC2 did not bind to ConA, was 44 kDa in size, and had a different subunit structure. STC2 was also a less effective inhibitor of gill Ca transport in fish. Collectively, the results suggest that there is a second form of STC in salmon.
ISSN:1522-1490