title: Alternative form of glucose-dependent insulinotropic polypepide and its physiology.
abstract: Glucose-dependent insulinotropic polypepide (GIP) was first extracted from porcine gut mucosa and identified as "incretin" decades ago. Though early studies have shown the possible GIP isoforms by gel filtration profiles from porcine or human intestinal extracts analyzed by radioimmunoassay (RIA), GIP is currently believed to consist of 42 amino acids (GIP1-42), which are released from gut K-cells and promote postprandial insulin release. In fact, GIP1-42 is usually processed from proGIP by the action of prohormone convertase (PC) 1/3 in the gut. GIP expression is occasionally found in the intestinal glucagon-like peptide-1-secreting cells, suggesting gene expression of both GIP and proglucagon can co-exist in identical cells. However, GIP1-42 immunoreactivity is rarely found in α-cells or other pancreatic endocrine cells of wild-type mammals. Interestingly, we found that short-form GIP1-30 is expressed in and released from pancreatic α-cells and a subset of enteroendocrine cells through proGIP processing by PC2. GIP1-30 is also insulinotropic and modulates glucose-stimulated insulin secretion in a paracrine manner. It is also suggested that short-form GIP1-30 possibly plays a crucial role for the islet development. It has not been well elucidated whether expression of GIP1-30 is modulated in the diabetic status, and whether GIP1-30 might have therapeutic potentials. Our preliminary data suggest that short-form GIP1-30 might play important roles in glucose metabolism.
authors.affiliation: Division of Metabolism and Biosystemic Science Department of Internal Medicine Asahikawa Medical University Asahikawa Hokkaido Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Fujita
authors.affiliation: Division of Metabolism and Biosystemic Science Department of Internal Medicine Asahikawa Medical University Asahikawa Hokkaido Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Yanagimachi
authors.affiliation: Division of Metabolism and Biosystemic Science Department of Internal Medicine Asahikawa Medical University Asahikawa Hokkaido Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Takeda
authors.affiliation: Division of Metabolism and Biosystemic Science Department of Internal Medicine Asahikawa Medical University Asahikawa Hokkaido Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Honjo
authors.affiliation: Division of Metabolism and Biosystemic Science Department of Internal Medicine Asahikawa Medical University Asahikawa Hokkaido Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Takiyama
authors.affiliation: Division of Metabolism and Biosystemic Science Department of Internal Medicine Asahikawa Medical University Asahikawa Hokkaido Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Abiko
authors.affiliation: Division of Metabolism and Biosystemic Science Department of Internal Medicine Asahikawa Medical University Asahikawa Hokkaido Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Makino
authors.affiliation: Division of Metabolism and Biosystemic Science Department of Internal Medicine Asahikawa Medical University Asahikawa Hokkaido Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Haneda
mesh_terms: D000818:Animals; D003920:Diabetes Mellitus / Q000188:drug therapy; D019858:Enteroendocrine Cells / Q000201:enzymology / Q000378:metabolism*; D005749:Gastric Inhibitory Polypeptide / Q000737:chemistry* / Q000502:physiology* / Q000627:therapeutic use; D050416:Glucagon-Secreting Cells / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006801:Humans; D054795:Incretins / Q000737:chemistry / Q000502:physiology; D051379:Mice; D010446:Peptide Fragments / Q000737:chemistry* / Q000502:physiology* / Q000627:therapeutic use; D045664:Proprotein Convertase 1 / Q000378:metabolism; D013552:Swine
chemical_list: D054795:Incretins; D010446:Peptide Fragments; C549099:gastric inhibitory polypeptide (1-30); D005749:Gastric Inhibitory Polypeptide; D045664:Proprotein Convertase 1; D005947:Glucose
keywords: Glucose‐dependent insulinotropic polypepide 1‐30; Hormone action and metabolism; Pancreatic α‐cells