Biochemical characterization of phospholipids, sulfatide and heparin as potent stimulators for autophosphorylation of GSK-3beta and the GSK-3beta-mediated phosphorylation of myelin basic protein in vitro.
The stimulatory effects of SH (sulfatide and heparin) and two phospholipids (PI and PS) on autophosphorylation of GSK-3beta and the GSK-3beta-mediated phosphorylation of myelin basic protein (MBP) and two synthetic MBP peptides (M86 and M156) were comparatively examined in vitro. It was found that (i) both PI and SH highly stimulated the GSK-3beta-mediated phosphorylation of MBP, but not glycogen synthase, and two MBP peptides through their direct binding to these substrates and (ii) both PI and heparin, as compared with sulfatide, highly stimulated autophosphorylation of GSK-3beta. The K(m) value of MBP for GSK-3beta was highly reduced and the V(max) value was significantly increased in the presence of these acidic modulators, which augmented further phosphorylation of MBP by the kinase. Under our experimental condition, similar stimulatory effects of PI and heparin were observed with the GSK-3beta-mediated phosphorylation of tau protein (TP) in vitro. These results presented here suggest that these two phospholipids and SH may function as effective stimulators for autophosphorylation of GSK-3beta and for the GSK-3beta-mediated high phosphorylation of SH-binding proteins, including MBP and TP, in the highly accumulated levels of these acidic and sulfated modulators in the brain.
Kawakami
Fumitaka
F
Laboratory of Genetical Biochemistry and Signal Biology, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Japan.
Yamaguchi
Akira
A
Suzuki
Kanzo
K
Yamamoto
Takayuki
T
Ohtsuki
Kenzo
K
D000818:Animals; D002417:Cattle; D006006:Glycogen Synthase / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006493:Heparin / Q000494:pharmacology*; D007700:Kinetics; D004676:Myelin Basic Protein / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D010449:Peptide Mapping; D010716:Phosphatidylinositols / Q000494:pharmacology*; D010718:Phosphatidylserines / Q000494:pharmacology*; D019606:Phosphoamino Acids / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D013379:Substrate Specificity / Q000187:drug effects; D013433:Sulfoglycosphingolipids / Q000494:pharmacology*; D013552:Swine
D004676:Myelin Basic Protein; D010446:Peptide Fragments; D010716:Phosphatidylinositols; D010718:Phosphatidylserines; D019606:Phosphoamino Acids; D013433:Sulfoglycosphingolipids; D006493:Heparin; D006006:Glycogen Synthase; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3