Monogalactosyl diglyceride, a marker for myelination, activates oligodendroglial protein kinase C.
Protein kinase C (PKC) is activated by 1,2-sn-diacylglycerol (DAG), the source of which can either be phosphatidylinositol bisphosphate or phosphatidylcholine. Here, we show that monogalactosyl diglyceride (MGDG), a minor galactolipid present in oligodendrocytes (OLs) and myelin, which is designated as a marker for myelination, can enhance OL PKC activity. Based on different calcium and substrate requirements we conclude that MGDG and DAG activate different isoforms of PKC group A: MGDG primarily stimulates PKC-alpha, and DAG primarily activates PKC-gamma. The presence of these PKC isoforms in OLs was confirmed by western blotting, whereas PKC-beta was only weakly stained, if at all. Addition of MGDG to the culture medium provided a higher density of regenerating OL fibers, which was not observed when membrane-permeable DAG was used. These findings indicate that MGDG can modulate the OL PKC activity and that PKC-alpha is the major PKC isoform involved in OL process formation.
Schmidt-Schultz
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Max-Planck-Institut für Experimentelle Medizin, Göttingen, F.R.G.
Althaus
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HH
D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000201:enzymology; D002122:Calcium Chloride / Q000494:pharmacology; D002478:Cells, Cultured; D004075:Diglycerides / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D038983:Galactolipids; D005690:Galactose / Q000378:metabolism; D006017:Glycolipids / Q000494:pharmacology*; D009186:Myelin Sheath / Q000502:physiology*; D009836:Oligodendroglia / Q000201:enzymology*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D013379:Substrate Specificity; D013552:Swine
D004075:Diglycerides; D038983:Galactolipids; D006017:Glycolipids; C009909:monogalactosyldiacylglycerol; D011493:Protein Kinase C; D002122:Calcium Chloride; D005690:Galactose