GIP1-39, a novel insulinotropic peptide form and aspects on its mechanism of action.
GIP1-39, a novel chain-length form of GIP (gastric inhibitory polypeptide or glucose-dependent insulinotropic polypeptide), has been purified recently from porcine intestine and found to exist abundantly in this tissue. We have characterized that GIP1-39 is an insulinotropic peptide, and demonstrated that GIP1-39 is more potent in stimulating insulin secretion from rat pancreatic islets than GIP1-42, the insulinotropic polypeptide reported originally. Therefore, we have further investigated some aspects on the mechanism behind the insulinotropic effect of GIP1-39 in single rat pancreatic beta cells. GIP1-39 at 100 nM was able to significantly increase intracellular Ca2+ concentration ([Ca2+]i), and capable of enhancing exocytosis assessed by membrane capacitance measurement. The novel GIP1-39 might be a more optimal molecular pattern in stimulating insulin secretion and deserves to be further investigated biologically and clinically.
Xie
Li
L
Institute of Biophysics and Biochemistry, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China.
Lu
Jie
J
Ostenson
Claes-Goran
CG
Xu
Tao
T
Chen
Zheng-Wang
ZW
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D005089:Exocytosis / Q000187:drug effects; D005749:Gastric Inhibitory Polypeptide / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats
D007328:Insulin; D010446:Peptide Fragments; C049962:gastric inhibitory polypeptide (1-39); D005749:Gastric Inhibitory Polypeptide; D002118:Calcium