title: Ablation of PDK1 in pancreatic beta cells induces diabetes as a result of loss of beta cell mass.
abstract: The total mass of islets of Langerhans is reduced in individuals with type 2 diabetes, possibly contributing to the pathogenesis of this condition. Although the regulation of islet mass is complex, recent studies have suggested the importance of a signaling pathway that includes the insulin or insulin-like growth factor-1 receptors, insulin receptor substrate and phosphatidylinositol (PI) 3-kinase. 3-Phosphoinositide-dependent protein kinase 1 (PDK1) is a serine-threonine kinase that mediates signaling downstream of PI 3-kinase. Here we show that mice that lack PDK1 specifically in pancreatic beta cells (betaPdk1-/- mice) develop progressive hyperglycemia as a result of a loss of islet mass. The mice show reductions in islet density as well as in the number and size of cells. Haploinsufficiency of the gene for the transcription factor Foxo1 resulted in a marked increase in the number, but not the size, of cells and resulted in the restoration of glucose homeostasis in betaPdk1-/- mice. These results suggest that PDK1 is important in maintenance of pancreatic cell mass and glucose homeostasis.
authors.affiliation: Department of Clinical Molecular Medicine, Division of Diabetes and Digestive and Kidney Diseases, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Hashimoto
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kido
authors.forename: Tohru
authors.initials: T
authors.lastname: Uchida
authors.forename: Shun-ichiro
authors.initials: S
authors.lastname: Asahara
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shigeyama
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Matsuda
authors.forename: Akihiko
authors.initials: A
authors.lastname: Takeda
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tsuchihashi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nishizawa
authors.forename: Wataru
authors.initials: W
authors.lastname: Ogawa
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Fujimoto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Okamura
authors.forename: Karen C
authors.initials: KC
authors.lastname: Arden
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Herrera
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Noda
authors.forename: Masato
authors.initials: M
authors.lastname: Kasuga
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D007515:Islets of Langerhans / Q000201:enzymology* / Q000473:pathology*; D051379:Mice; D018345:Mice, Knockout; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D015398:Signal Transduction
chemical_list: D064413:3-Phosphoinositide-Dependent Protein Kinases; C578564:Pdpk1 protein, mouse; D017346:Protein Serine-Threonine Kinases