Sialosylcholesterol effects on reconstitution of microfilament and glia filament.
The effects of alpha-sialosylcholesterol (alpha-SC) on formation of either microfilament or glia filament of rat astrocytes were investigated using a reconstitution system. Polymerization of the depolymerized microfilament preparation that had been extracted from a crude cytoskeletal fraction of rat astrocytes, in the presence of 100 mM KCl and 10 mM MgCl2, was suppressed in a dose-dependent manner by alpha-SC. alpha-SC inhibited polymerization of G-actin in a similar manner. The intensity of alpha-SC inhibition of G-actin polymerization was as great as that of microfilament polymerization, suggesting that the inhibition of microfilament polymerization by alpha-SC was due to the direct action of alpha-SC on actin, the main component of microfilament. alpha-SC depolymerized partly the polymerized microfilament preparation, which resembled F-actin (microfilament-like filaments). alpha-SC suppressed, in a dose-dependent manner, polymerization of a glia filament preparation that had been extracted from astrocyte cytoskeletons in the presence of phalloidin. An increase in the amount of added alpha-SC (up to 15 microM) decreased the amount of the larger glia filament-like filaments, which were 10 nm thick and centrifuged down at 16,000 g for 30 min, and increased that of smaller ones precipitated only after centrifugation at 100,000 g for 1 h. The lower the concentration of the depolymerized glia filament extract, the greater was the inhibition by alpha-SC of the polymerization. alpha-SC repressed polymerization of vimentin, the dominant component of glia filament. Vimentin polymerization was more strongly inhibited by alpha-SC than polymerization of glia filament was.(ABSTRACT TRUNCATED AT 250 WORDS)
Ito
J
J
Department of Biochemistry, Nagoya City University Medical School, Japan.
Masuda
M
M
Tanaka
R
R
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D001921:Brain / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D002788:Cholesterol Esters / Q000494:pharmacology*; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D007700:Kinetics; D008297:Male; D008840:Microfilament Proteins / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D051381:Rats; D017208:Rats, Wistar; D012794:Sialic Acids / Q000494:pharmacology*; D013997:Time Factors; D014746:Vimentin / Q000378:metabolism
D002788:Cholesterol Esters; D008840:Microfilament Proteins; D012794:Sialic Acids; D014746:Vimentin; C055195:N-acetylneuraminyl cholesterol