Effect of Choline-Containing Phospholipids on Transglutaminase Activity in Primary Astroglial Cell Cultures

The aim of the present investigation was to study the effects of choline and cholinecontaining phospholipids CDP-choline (CDPC) and L-alpha-glyceryl-phosphorylcholine (alpha-GPC) on transglutaminase (TG) activity and expression in primary astrocyte cultures. TG is an important Ca2+ -dependent protein that represents a normal constituent of nervous systems during fetal stages of development, playing a role in cell signal transduction, differentiation, and apoptosis. Confocal laser scanning microscopy (CLSM) analysis showed an increase of TG activity in astrocyte cultures treated with choline, CDPC, or alpha-GPC at 0.1 mM or 1 mM concentrations. Comparatively, alpha-GPC induced the most conspicuous effects enhancing monodansyl-cadaverine fluorescence both in cytosol and in nuclei, supporting the evidence of the important role played by alpha-GPC throughout differentiation processes tightly correlated to nucleus-cytosol cross-talk during astroglial cells proliferation and development. Western blot analysis showed that in 24h 1 mM alpha-GPC and choline-treated astrocytes increased TG-2, whereas no effect was observed in 24h 1 mM CDP-choline treated astrocytes. Our data suggest a crucial role of choline precursors during different stages of astroglial cell proliferation and differentiation in cultures.