A possible role of transglutaminase 2 in the nucleus of INS-1E and of cells of human pancreatic islets

作者：Sileno Sara; D'Oria Valentina; Stucchi Riccardo; Alessio Massimo; Petrini Stefania; Bonetto Valentina; Maechler Pierre; Bertuzzi Federico; Grasso Valeria; Paolella Katia; Barbetti Fabrizio; Massa Ornella^*

来源：Journal of Proteomics, 2014, 96: 314-327.

DOI：10.1016/j.jprot.2013.11.011

• Transglutaminase 2
• Insulin secretion
• Calcium concentration
• beta-Cell
• INS-1E
• Human islet

Transglutaminase 2 (TG2) is a multifunctional protein with Ca2+-dependent transamidating and G protein activity. Previously we reported that the role of TG2 in insulin secretion may involve cytoplasmic actin remodeling and a regulative action on other proteins during granule movement. The aim of this study was to gain a better insight into the role of TG2 transamidating activity in mitochondria and in the nucleus of INS-1E rat insulinoma cell line (INS-1E) during insulin secretion. To this end we labeled INS-1E with an artificial donor (biotinylated peptide), in basal condition and after stimulus with glucose for 2, 5, and 8 min. Biotinylated proteins of the nuclear/mitochondrial-enriched fraction were analyzed using two-dimensional electrophoresis and mass spectrometry. Many mitochondrial proteins involved in Ca2+ homeostasis (e.g. voltage-dependent anion-selective channel protein, prohibitin and different ATP synthase subunits) and many nuclear proteins involved in gene regulation (e.g. histone H3, barrier to autointegration factor and various heterogeneous nuclear ribonucleoprotein) were identified among a number of transamidating substrates of TG2 in INS-1E. The combined results provide evidence that a temporal link exists between glucose-stimulation, first phase insulin secretion and the action of TG on histone H3 both in INS-1E and human pancreatic islets.
Biological significance Research into the role of transglutaminase 2 during insulin secretion in INS-1E rat insulinoma cellular model is depicting a complex role for this enzyme. Transglutaminase 2 acts in the different INS-1E compartments in the same way: catalyzing a post-translational modification event of its substrates. In this work we identify some mitochondrial and nuclear substrates of INS-1E during first phase insulin secretion. The finding that TG2 interacts with nuclear proteins that include BAP and histone H3 immediately after (2-5 min) glucose stimulus of INS-1E suggests that TG2 may be involved not only in insulin secretion, as suggested by our previous studies in cytoplasmic INS-1E fraction, but also in the regulation of glucose-induced gene transcription.

• 出版日期2014-1-16