Kerr, Barry D., Flatt, Anneliese J. S., Flatt, Peter and Gault, Victor (2011) Characterization and biological actions of N-terminal truncated forms of glucose-dependent insulinotropic polypeptide. BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 404 (3). pp. 870-876. [Journal article]
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The N-terminal domain of glucose-dependent insulinotropic polypeptide (GIP) plays an important role in regulating biological activity. This study examined biological properties of several N-terminal truncated forms of GIP and two novel forms with substitutions at Phe position-6 with Arg or Val. GIP(6-42), GIP(R6-42), GIP(V6-42), GIP(7-42) and GIP(9-42) stimulated cAMP production in BRIN-BD11 cells similar to native GIP, whereas responses to GIP(3-42), GIP(4-42), GIP(5-42) and GIP(8-42) were reduced (P < 0.01 to P < 0.001). GIP-induced cyclic AMP production was significantly inhibited by GIP(3-42), GIP(4-42), GIP(5-42), GIP(6-42), GIP(R6-42), GIP(7-42) and GIP(8-42) (P < 0.001). Compared with native GIP, in vitro insulinotropic activity of GIP(3-42), GIP(4-42), GIP(5-42), GIP(7-42) and GIP(8-42) was reduced (P < 0.05 to P < 0.001), with GIP(4-42), GIP(5-42), GIP(7-42) and GIP(8-42) also potently inhibiting GIP-stimulated insulin secretion (P < 0.001). In ob/ob mice, GIP(4-42) and GIP(8-42) increased (P < 0.05 to P < 0.01) plasma glucose concentrations compared to the glucose-lowering action of native GIP. When GIP(8-42) was co-administered with native GIP it countered the ability of the native peptide to lower plasma glucose and increase circulating insulin concentrations. These data confirm the importance of the N-terminal region of GIP in regulating bioactivity and reveal that sequential truncation of the peptide yields novel GIP receptor antagonists which may have functional significance. (C) 2010 Elsevier Inc. All rights reserved.
|Item Type:||Journal article|
|Faculties and Schools:||Faculty of Life and Health Sciences > School of Biomedical Sciences|
Faculty of Life and Health Sciences
|Research Institutes and Groups:||Biomedical Sciences Research Institute|
Biomedical Sciences Research Institute > Diabetes
|Deposited By:||Dr Nigel Irwin|
|Deposited On:||30 Jun 2011 12:46|
|Last Modified:||30 Jun 2011 12:46|
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