Journal of Neuroscience, Vol 8, 4307-4318, Copyright © 1988 by Society for Neuroscience
Antibody to galactocerebroside alters organization of oligodendroglial membrane sheets in culture
CA Dyer and JA Benjamins
Department of Neurology, Wayne State University School of Medicine, Detroit, Michigan 48201.
Antibodies to galactocerebroside (GalC) cause major changes in the
organization of the membrane sheets elaborated by murine oligodendroglia in
culture. Exposure of oligodendroglia to rabbit anti- GalC IgG for 15 min
followed by fluoresceinated second antibodies results in patches of surface
GalC staining; when second antibodies are applied after 2 hr of anti-GalC,
the pattern of staining on membrane sheets is solid and wrinkled. Anti-GalC
exposure for 24 hr results in contracted membrane sheets. No membrane
contraction is detected in cultures treated with anti-sulfatide IgM or
anti-proteolipid protein IgG. In cultures exposed to anti-GalC continuously
for 4-7 d, there is a marked decrease in numbers of extended membrane
sheets with an accompanying increase in contracted sheets. This effect is
reversible upon removal of anti-GalC from the culture media. By scanning
electron microscopy, normally flat membrane sheets appear ruffled after 2
hr of anti-GalC treatment; by 24 hr, contracted membrane sheets consist
entirely of bulbous protrusions. Oligodendrocyte membranes exposed to
anti-sulfatide for 24 hr are not contracted but are covered with bulbous
protrusions. The organization of underlying membrane structures was
examined in relation to membrane patching and sheet contraction. In
membranes with patching induced by exposure to anti-GalC for 15 min, the
anti-GalC: GalC complexes are localized over cytoplasmic MBP domains, with
the unstained areas located above cytoplasmic microtubular structures.
Membrane sheets that are contracted in response to anti-GalC exposure for
6-24 hr show intense GalC staining over microtubular structures. Anti-GalC
exposure does not change metabolism of GalC; in cultures incubated with
3H-galactose and anti- GalC for 24 hr, there are no alterations in GalC
labeling compared with control cultures. In summary, these results provide
direct evidence that interaction between surface glycolipids and external
antibodies can initiate a sequence of events leading to dramatic changes
within the oligodendrocyte.
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