Journal of Neuroscience, Vol 7, 1833-1842, Copyright © 1987 by Society for Neuroscience
Acetylation of alpha-tubulin in cultured neurons and the induction of alpha-tubulin acetylation in PC12 cells by treatment with nerve growth factor
MM Black and P Keyser
alpha-Tubulin of cultured neurons undergoes a posttranslational
modification that lowers its p/(Black and Kurdyla, 1983a). We show here
that this modification is due to acetylation. Incubation of cultures with
3H-acetate results in the prominent labeling of a protein that comigrates
with alpha-tubulin in 1-dimensional SDS gels, and in 2- dimensional
isoelectric focusing X SDS gels, it comigrates with the more acidic
alpha-tubulin forms. The labeled material can be immunoprecipitated by
monoclonal antibodies to alpha-tubulin but not by antibodies to
beta-tubulin. The reaction occurs to equal extent in the presence or
absence of 0.1 mM cycloheximide or unlabeled amino acids. These
observations indicate that the reaction is posttranslational and is not
secondary to conversion of isotopic acetate into amino acids. The
posttranslational nature of tubulin acetylation was further established by
the demonstration that acetate is incorporated into alpha-tubulin in
neurites, which lack the capacity for cytoplasmic protein synthesis.
Finally, a monoclonal antibody that is specific for acetylated
alpha-tubulin (Piperno and Fuller, 1985) recognizes the acidic variants of
alpha-tubulin of cultured neurons that can be labeled by incubation with
3H-acetate. Collectively, these observations indicate that alpha-tubulin of
cultured sympathetic neurons undergoes a posttranslational acetylation.
Immunofluorescence analyses using a monoclonal antibody specific for
acetylated alpha-tubulin revealed that it was present throughout the neuron
and showed no obvious regional compartmentalization. We have also shown
that alpha-tubulin is acetylated in the NGF-responsive PC12 line of
pheochromocytoma cells using biochemical and immunological criteria.
However, this modification was detected only in long-term (14 d)
NGF-treated cells. The results are discussed in terms of the possible role
of acetylation as a local mechanism for regulating microtubule stability.