title: PI3K regulates endocytosis after insulin secretion by mediating signaling crosstalk between Arf6 and Rab27a.
abstract: In secretory cells, endocytosis is coupled to exocytosis to enable proper secretion. Although endocytosis is crucial to maintain cellular homeostasis before and after secretion, knowledge about secretagogue-induced endocytosis in secretory cells is still limited. Here, we searched for proteins that interacted with the Rab27a GTPase-activating protein (GAP) EPI64 (also known as TBC1D10A) and identified the Arf6 guanine-nucleotide-exchange factor (GEF) ARNO (also known as CYTH2) in pancreatic β-cells. We found that the insulin secretagogue glucose promotes phosphatidylinositol (3,4,5)-trisphosphate (PIP3) generation through phosphoinositide 3-kinase (PI3K), thereby recruiting ARNO to the intracellular side of the plasma membrane. Peripheral ARNO promotes clathrin assembly through its GEF activity for Arf6 and regulates the early stage of endocytosis. We also found that peripheral ARNO recruits EPI64 to the same area and that the interaction requires glucose-induced endocytosis in pancreatic β-cells. Given that GTP- and GDP-bound Rab27a regulate exocytosis and the late stage of endocytosis, our results indicate that the glucose-induced activation of PI3K plays a pivotal role in exocytosis-endocytosis coupling, and that ARNO and EPI64 regulate endocytosis at distinct stages.
authors.affiliation: Department of Pharmacology, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita 879-5593, Japan.
authors.forename: Mami
authors.initials: M
authors.lastname: Yamaoka
authors.affiliation: Department of Pharmacology, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita 879-5593, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Ando
authors.affiliation: Department of Pharmacology, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita 879-5593, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Terabayashi
authors.affiliation: Department of Pharmacology, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita 879-5593, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Okamoto
authors.affiliation: Department of Pharmacology, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita 879-5593, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takei
authors.affiliation: Department of Cell Pharmacology, Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa, Nagoya, Aichi 466-8550, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Nishioka
authors.affiliation: Department of Cell Pharmacology, Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa, Nagoya, Aichi 466-8550, Japan JST, CREST, 4-1-8 Honcho, Kawaguchi 332-0012, Japan.
authors.forename: Kozo
authors.initials: K
authors.lastname: Kaibuchi
authors.affiliation: Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan.
authors.forename: Kohichi
authors.initials: K
authors.lastname: Matsunaga
authors.affiliation: Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan.
authors.forename: Ray
authors.initials: R
authors.lastname: Ishizaki
authors.affiliation: Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Izumi
authors.affiliation: Department of Pharmacology, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita 879-5593, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Niki
authors.affiliation: Department of Pharmacology, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita 879-5593, Japan.
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Ishizaki
authors.affiliation: Department of Pharmacology, Oita University Faculty of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita 879-5593, Japan t-kimura@oita-u.ac.jp.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Kimura
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000378:metabolism*; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D004705:Endocytosis / Q000502:physiology*; D005089:Exocytosis / Q000502:physiology; D020690:GTPase-Activating Proteins / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000378:metabolism; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000075745:rab27 GTP-Binding Proteins
chemical_list: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors; D020690:GTPase-Activating Proteins; D005947:Glucose; D007328:Insulin; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D020691:rab GTP-Binding Proteins; D000075745:rab27 GTP-Binding Proteins; C512962:Rab27a protein, mouse; C000715727:Arf6 protein, mouse
keywords: Diabetes; Endocytosis; Insulin; Membrane trafficking; Pancreatic β-cells; Small GTPase