title: Loss-of-Function Mutations in APPL1 in Familial Diabetes Mellitus.
abstract: Diabetes mellitus is a highly heterogeneous disorder encompassing several distinct forms with different clinical manifestations including a wide spectrum of age at onset. Despite many advances, the causal genetic defect remains unknown for many subtypes of the disease, including some of those forms with an apparent Mendelian mode of inheritance. Here we report two loss-of-function mutations (c.1655T>A [p.Leu552(∗)] and c.280G>A [p.Asp94Asn]) in the gene for the Adaptor Protein, Phosphotyrosine Interaction, PH domain, and leucine zipper containing 1 (APPL1) that were identified by means of whole-exome sequencing in two large families with a high prevalence of diabetes not due to mutations in known genes involved in maturity onset diabetes of the young (MODY). APPL1 binds to AKT2, a key molecule in the insulin signaling pathway, thereby enhancing insulin-induced AKT2 activation and downstream signaling leading to insulin action and secretion. Both mutations cause APPL1 loss of function. The p.Leu552(∗) alteration totally abolishes APPL1 protein expression in HepG2 transfected cells and the p.Asp94Asn alteration causes significant reduction in the enhancement of the insulin-stimulated AKT2 and GSK3β phosphorylation that is observed after wild-type APPL1 transfection. These findings-linking APPL1 mutations to familial forms of diabetes-reaffirm the critical role of APPL1 in glucose homeostasis.
authors.affiliation: Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy. Electronic address: s.prudente@css-mendel.it.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Prudente
authors.affiliation: Research Division, Joslin Diabetes Center, Boston, MA 02215, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Prapaporn
authors.initials: P
authors.lastname: Jungtrakoon
authors.affiliation: Research Unit of Diabetes and Endocrine Diseases, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Marucci
authors.affiliation: Research Unit of Diabetes and Endocrine Diseases, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
authors.forename: Ornella
authors.initials: O
authors.lastname: Ludovico
authors.affiliation: Research Division, Joslin Diabetes Center, Boston, MA 02215, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Patinut
authors.initials: P
authors.lastname: Buranasupkajorn
authors.affiliation: Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Mazza
authors.affiliation: Research Division, Joslin Diabetes Center, Boston, MA 02215, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Hastings
authors.affiliation: Department of Biochemical Sciences, Sapienza University, 00185 Rome, Italy.
authors.forename: Teresa
authors.initials: T
authors.lastname: Milano
authors.affiliation: Research Unit of Diabetes and Endocrine Diseases, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Morini
authors.affiliation: Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
authors.forename: Luana
authors.initials: L
authors.lastname: Mercuri
authors.affiliation: Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; Department of Experimental Medicine, Sapienza University, 00161 Rome, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Bailetti
authors.affiliation: Research Division, Joslin Diabetes Center, Boston, MA 02215, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Mendonca
authors.affiliation: Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Alberico
authors.affiliation: Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; Department of Experimental Medicine, Sapienza University, 00161 Rome, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Basile
authors.affiliation: Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Romani
authors.affiliation: Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
authors.forename: Elide
authors.initials: E
authors.lastname: Miccinilli
authors.affiliation: Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; Department of Experimental Medicine, Sapienza University, 00161 Rome, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Pizzuti
authors.affiliation: Unit of Medical Genetics, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Carella
authors.affiliation: Laboratory of Mendelian Diabetes, Bambino Gesù Childrens' Hospital, 00165 Rome, Italy; Department of Experimental Medicine and Surgery, University of Tor Vergata, 00133 Rome, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Barbetti
authors.affiliation: Department of Biochemical Sciences, Sapienza University, 00185 Rome, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Pascarella
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, 56127 Pisa, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Marchetti
authors.affiliation: Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; Research Unit of Diabetes and Endocrine Diseases, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy; Department of Experimental Medicine, Sapienza University, 00161 Rome, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Trischitta
authors.affiliation: Research Unit of Diabetes and Endocrine Diseases, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Di Paola
authors.affiliation: Research Division, Joslin Diabetes Center, Boston, MA 02215, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA. Electronic address: alessandro.doria@joslin.harvard.edu.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Doria
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000235:genetics*; D000328:Adult; D000368:Aged; D003920:Diabetes Mellitus / Q000235:genetics*; D005260:Female; D056945:Hep G2 Cells; D006801:Humans; D015151:Immunoblotting; D007328:Insulin / Q000378:metabolism; D007558:Italy; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D020125:Mutation, Missense / Q000235:genetics*; D010375:Pedigree; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D014481:United States
chemical_list: C464801:APPL1 protein, human; D048868:Adaptor Proteins, Signal Transducing; D007328:Insulin; C494921:AKT2 protein, human; D051057:Proto-Oncogene Proteins c-akt