TY - JOUR

T1 - Prohormone convertase 1/3 is essential for processing of the glucose-dependent insulinotropic polypeptide precursor

AU - Ugleholdt, Randi

AU - Poulsen, Marie-Louise H

AU - Holst, Peter J

AU - Irminger, Jean-Claude

AU - Orskov, Cathrine

AU - Pedersen, Jens

AU - Rosenkilde, Mette M

AU - Zhu, Xiaorong

AU - Steiner, Donald F

AU - Holst, Jens Juul

N1 - Nøgleord: Adenoviridae; Dyr, COS celler Cell Line; Cells, Kulturperler, Cercopithecus aethiops, Chromatography, Gel, Chromatography, High Pressure Liquid; cyklisk AMP, DNA, supplerer hinanden; dosis-respons sammenhæng, Drug; Flowcytometri; Gastrisk Inhibitory Polypeptid; genetiske Vektorer, Glucose, Immunhistokemi, Insulin, Tarm, mus, mus, transgene; Modeller, genetiske, Peptider, polymerasekædereaktion; Proprotein Convertase 1; Proprotein Convertases, RNA, RNA, Messenger, Radioimmunoassay, Rotter, receptorer, Mave-hormon; rekombinant Proteiner

PY - 2006

Y1 - 2006

N2 - The physiology of the incretin hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), and their role in type 2 diabetes currently attract great interest. Recently we reported an essential role for prohormone convertase (PC) 1/3 in the cleavage of intestinal proglucagon, resulting in formation of GLP-1, as demonstrated in PC1/3-deficient mice. However, little is known about the endoproteolytic processing of the GIP precursor. This study investigates the processing of proGIP in PC1/3 and PC2 null mice and in cell lines using adenovirus-mediated overexpression. Supporting a role for PC1/3 in proGIP processing, we found co-localization of GIP and PC1/3 but not PC2 in intestinal sections by immunohistochemistry, and analysis of intestinal extracts from PC1/3-deficient animals demonstrated severely impaired processing to GIP, whereas processing to GIP was unaltered in PC2-deficient mice. Accordingly, overexpression of preproGIP in the neuroendocrine AtT-20 cell line that expresses high levels of endogenous PC1/3 and negligible levels of PC2 resulted in production of GIP. Similar results were obtained after co-expression of preproGIP and PC1/3 in GH4 cells that express no PC2 and only low levels of PC1/3. In addition, studies in GH4 cells and the alpha-TC1.9 cell line, expressing PC2 but not PC1/3, indicate that PC2 can mediate processing to GIP but also to other fragments not found in intestinal extracts. Taken together, our data indicate that PC1/3 is essential and sufficient for the production of the intestinal incretin hormone GIP, whereas PC2, although capable of cleaving proGIP, does not participate in intestinal proGIP processing and is not found in intestinal GIP-expressing cells.

AB - The physiology of the incretin hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), and their role in type 2 diabetes currently attract great interest. Recently we reported an essential role for prohormone convertase (PC) 1/3 in the cleavage of intestinal proglucagon, resulting in formation of GLP-1, as demonstrated in PC1/3-deficient mice. However, little is known about the endoproteolytic processing of the GIP precursor. This study investigates the processing of proGIP in PC1/3 and PC2 null mice and in cell lines using adenovirus-mediated overexpression. Supporting a role for PC1/3 in proGIP processing, we found co-localization of GIP and PC1/3 but not PC2 in intestinal sections by immunohistochemistry, and analysis of intestinal extracts from PC1/3-deficient animals demonstrated severely impaired processing to GIP, whereas processing to GIP was unaltered in PC2-deficient mice. Accordingly, overexpression of preproGIP in the neuroendocrine AtT-20 cell line that expresses high levels of endogenous PC1/3 and negligible levels of PC2 resulted in production of GIP. Similar results were obtained after co-expression of preproGIP and PC1/3 in GH4 cells that express no PC2 and only low levels of PC1/3. In addition, studies in GH4 cells and the alpha-TC1.9 cell line, expressing PC2 but not PC1/3, indicate that PC2 can mediate processing to GIP but also to other fragments not found in intestinal extracts. Taken together, our data indicate that PC1/3 is essential and sufficient for the production of the intestinal incretin hormone GIP, whereas PC2, although capable of cleaving proGIP, does not participate in intestinal proGIP processing and is not found in intestinal GIP-expressing cells.

U2 - 10.1074/jbc.M601203200

DO - 10.1074/jbc.M601203200

M3 - Journal article

C2 - 16476726

VL - 281

SP - 11050

EP - 11057

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 16

ER -