title: Role of GALNT2 in the modulation of ENPP1 expression, and insulin signaling and action: GALNT2: a novel modulator of insulin signaling.
abstract: Ectonucleotide pyrophosphatase phosphodiesterase 1 (ENPP1) inhibits insulin signaling and action. Understanding the mechanisms underlying ENPP1 expression may help unravel molecular mechanisms of insulin resistance. Recent data suggest a role of ENPP1-3'untraslated region (UTR), in controlling ENPP1 expression. We sought to identify trans-acting ENPP1-3'UTR binding proteins, and investigate their role on insulin signaling. By RNA pull-down, 49 proteins bound to ENPP1-3'UTR RNA were identified by mass spectrometry (MS). Among these, in silico analysis of genome wide association studies and expression profile datasets pointed to N-acetylgalactosaminyltransferase 2 gene (GALNT2) for subsequent investigations. Gene expression levels were evaluated by RT-PCR. Protein expression levels, IRS-1 and Akt phosphorylation were evaluated by Western blot. Insulin receptor (IR) autophosphorylation was evaluated by ELISA. GALNT2 down-regulation increased while GALNT2 over-expression reduced ENPP1 expression levels. In addition, GALNT2 down-regulation reduced insulin stimulation of IR, IRS-1 and Akt phosphorylation and insulin inhibition of phosphoenolpyruvate carboxykinase (PEPCK) expression, a key neoglucogenetic enzyme. Our data point to GALNT2 as a novel factor involved in the modulation of ENPP1 expression as well as insulin signaling and action in human liver HepG2 cells.
authors.affiliation: Research Unit of Diabetes and Endocrine Diseases, Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Marucci
authors.forename: Flora
authors.initials: F
authors.lastname: Cozzolino
authors.forename: Claudia
authors.initials: C
authors.lastname: Dimatteo
authors.forename: Maria
authors.initials: M
authors.lastname: Monti
authors.forename: Piero
authors.initials: P
authors.lastname: Pucci
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Trischitta
authors.forename: Rosa
authors.initials: R
authors.lastname: Di Paola
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics*; D015415:Biomarkers / Q000378:metabolism*; D002478:Cells, Cultured; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D056945:Hep G2 Cells; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D017350:N-Acetylgalactosaminyltransferases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010727:Phosphoric Diester Hydrolases / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D011755:Pyrophosphatases / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D011972:Receptor, Insulin / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D000097763:Polypeptide N-acetylgalactosaminyltransferase
chemical_list: D020413:3' Untranslated Regions; D015415:Biomarkers; D007328:Insulin; D008156:Luciferases; D017350:N-Acetylgalactosaminyltransferases; D010727:Phosphoric Diester Hydrolases; D011755:Pyrophosphatases; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011972:Receptor, Insulin; D000097763:Polypeptide N-acetylgalactosaminyltransferase; C065962:ectonucleotide pyrophosphatase phosphodiesterase 1