title: Soybean beta 51-63 peptide stimulates cholecystokinin secretion via a calcium-sensing receptor in enteroendocrine STC-1 cells.
abstract: We previously demonstrated that intraduodenal administration of an arginine-rich beta 51-63 peptide in soybean beta-conglycinin suppresses food intake via cholecystokinin (CCK) secretion in rats. However, the cellular mechanisms by which the beta 51-63 peptide induces CCK secretion remain to be clarified. In the present study, we examined whether the extracellular calcium-sensing receptor (CaR) mediates beta 51-63-induced CCK secretion in murine CCK-producing enteroendocrine cell line STC-1. CCK secretion and changes in intracellular Ca(2+) concentration in response to beta 51-63 peptide were measured in STC-1 cells under various extracellular Ca(2+) concentrations and after treatment with a CaR antagonist. Intracellular Ca(2+) concentrations in response to beta 51-63 peptide and extracellular Ca(2+) were also measured in CaR-expressing human embryonic kidney (HEK-293) cells. The beta 51-63 peptide induced CCK secretion and intracellular Ca(2+) mobilization in STC-1 cells under normal (1.2mM) extracellular Ca(2+) conditions in a dose-dependent manner. These responses to beta 51-63 peptide were reduced by the removal of intra- or extracellular Ca(2+) but enhanced by increasing extracellular Ca(2+) concentrations. Intracellular Ca(2+) mobilization induced by extracellular Ca(2+) was also increased by the pretreatment with beta 51-63 peptide. Treatment with a specific CaR antagonist (NPS2143) inhibited beta 51-63-induced CCK secretion and intracellular Ca(2+) mobilization. In addition, HEK-293 cells transfected with CaR acquired sensitivity to the beta 51-63 peptide. From these results, we conclude that CaR is the beta 51-63 peptide sensor responsible for the stimulation of CCK secretion in enteroendocrine STC-1 cells.
authors.affiliation: Division of Bio-systems and Sustainability, Graduate School of Agriculture, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Nakajima
authors.forename: Tohru
authors.initials: T
authors.lastname: Hira
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Eto
authors.forename: Kozo
authors.initials: K
authors.lastname: Asano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hara
mesh_terms: D000818:Animals; D052179:Antigens, Plant / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002766:Cholecystokinin / Q000378:metabolism*; D019858:Enteroendocrine Cells / Q000378:metabolism*; D005916:Globulins / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D044169:Receptors, Calcium-Sensing / Q000819:agonists* / Q000235:genetics / Q000378:metabolism*; D055314:Seed Storage Proteins / Q000494:pharmacology*; D030262:Soybean Proteins / Q000494:pharmacology*
chemical_list: D052179:Antigens, Plant; D005916:Globulins; D010455:Peptides; D044169:Receptors, Calcium-Sensing; D055314:Seed Storage Proteins; D030262:Soybean Proteins; C013894:beta-conglycinin protein, Glycine max; D002766:Cholecystokinin; D002118:Calcium