INVESTIGADORES
BISIG Carlos Gaston
artículos
Título:
Post-translational incorporation of the antiproliferative agent azatyrosine into the C-terminus of alpha-tubulin.
Autor/es:
PURRO SA, BISIG CG, CONTIN MA, BARRA HS, ARCE CA.
Revista:
BIOCHEMICAL JOURNAL
Referencias:
Año: 2003 vol. OCT p. 121 - 129
ISSN:
0264-6021
Resumen:
Detyrosination/tyrosination of tubulin is a post-translational
modification that occurs at the C-terminus of the alpha-subunit, giving
rise to microtubules rich in either tyrosinated or detyrosinated
tubulin which coexist in the cell. We hereby report that the tyrosine
analogue, azatyrosine, can be incorporated into the C-terminus of
alpha-tubulin instead of tyrosine. Azatyrosine is structurally
identical to tyrosine except that a nitrogen atom replaces carbon-2 of
the phenolic group. Azatyrosine competitively excluded incorporation of
[14C]tyrosine into tubulin of soluble brain extract. A newly developed
rabbit antibody specific to C-terminal azatyrosine was used to study
incorporation of azatyrosine in cultured cells. When added to the
culture medium (Ham's F12K), azatyrosine was incorporated into tubulin
of glioma-derived C6 cells. This incorporation was reversible, i.e.
after withdrawal of azatyrosine, tubulin lost azatyrosine and
reincorporated tyrosine. Azatyrosinated tubulin self-assembled into
microtubules to a similar degree as total tubulin both in vitro and in
vivo. Studies by other groups have shown that treatment of certain
types of cultured cancer cells with azatyrosine leads to reversion of
phenotype to normal, and that administration of azatyrosine into
animals harbouring human proto-oncogenic c-Ha- ras prevents tumour
formation. These interesting observations led us to study this
phenomenon in relation to tubulin status. Under conditions in which
tubulin was mostly azatyrosinated, C6 cells remained viable but did not
proliferate. After 7-10 days under these conditions, morphology changed
from a fused, elongated shape to a rounded soma with thin processes.
Incorporation of azatyrosine into the C-terminus of alpha-tubulin is
proposed as one possible cause of reversion of the malignant phenotype.