1. Role of GALNT2 in the modulation of ENPP1 expression, and insulin signaling and action: GALNT2: a novel modulator of insulin signaling
- Author
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Antonella, Marucci, Flora, Cozzolino, Claudia, Dimatteo, Maria, Monti, Piero, Pucci, Trischitta, Vincenzo, and Rosa Di Paola
- Subjects
3'utr binding proteins ,galnt2 ,Kidney ,Real-Time Polymerase Chain Reaction ,enpp1 ,Humans ,Insulin ,RNA, Messenger ,Phosphorylation ,Pyrophosphatases ,RNA, Small Interfering ,Luciferases ,insulin signaling ,3' Untranslated Regions ,3 ' utr binding proteins ,Cells, Cultured ,Oligonucleotide Array Sequence Analysis ,Phosphoric Diester Hydrolases ,Reverse Transcriptase Polymerase Chain Reaction ,Gene Expression Profiling ,Hep G2 Cells ,Receptor, Insulin ,Gene Expression Regulation ,N-Acetylgalactosaminyltransferases ,Biomarkers ,Signal Transduction - 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.
- Published
- 2012