title: Glucokinase (GCK) mutations and their characterization in MODY2 children of southern Italy.
abstract: Type 2 Maturity Onset Diabetes of the Young (MODY2) is a monogenic autosomal disease characterized by a primary defect in insulin secretion and hyperglycemia. It results from GCK gene mutations that impair enzyme activity. Between 2006 and 2010, we investigated GCK mutations in 66 diabetic children from southern Italy with suspected MODY2. Denaturing High Performance Liquid Chromatography (DHPLC) and sequence analysis revealed 19 GCK mutations in 28 children, six of which were novel: p.Glu40Asp, p.Val154Leu, p.Arg447Glyfs, p.Lys458_Cys461del, p.Glu395_Arg397del and c.580-2A>T. We evaluated the effect of these 19 mutations using bioinformatic tools such as Polymorphism Phenotyping (Polyphen), Sorting Intolerant From Tolerant (SIFT) and in silico modelling. We also conducted a functional study to evaluate the pathogenic significance of seven mutations that are among the most severe mutations found in our population, and have never been characterized: p.Glu70Asp, p.His137Asp, p.Phe150Tyr, p.Val154Leu, p.Gly162Asp, p.Arg303Trp and p.Arg392Ser. These seven mutations, by altering one or more kinetic parameters, reduced enzyme catalytic activity by >40%. All mutations except p.Glu70Asp displayed thermal-instability, indeed >50% of enzyme activity was lost at 50°C/30 min. Thus, these seven mutations play a pathogenic role in MODY2 insurgence. In conclusion, this report revealed six novel GCK mutations and sheds some light on the structure-function relationship of human GCK mutations and MODY2.
authors: Department of Biochemistry and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors: Marina
authors: M
authors: Capuano
authors: Carmen Maria
authors: CM
authors: Garcia-Herrero
authors: Nadia
authors: N
authors: Tinto
authors: Carla
authors: C
authors: Carluccio
authors: Valentina
authors: V
authors: Capobianco
authors: Iolanda
authors: I
authors: Coto
authors: Arturo
authors: A
authors: Cola
authors: Dario
authors: D
authors: Iafusco
authors: Adriana
authors: A
authors: Franzese
authors: Adriana
authors: A
authors: Zagari
authors: Maria Angeles
authors: MA
authors: Navas
authors: Lucia
authors: L
authors: Sacchetti
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002648:Child; D002851:Chromatography, High Pressure Liquid; D019295:Computational Biology; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D005941:Glucokinase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007558:Italy; D007700:Kinetics; D008297:Male; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D011487:Protein Conformation
chemical_list: D000255:Adenosine Triphosphate; D005941:Glucokinase