Fernando Cabral

Learn More
A sensitive and reproducible method to measure relative levels of polymerized and soluble tubulin in cells has been developed. This method involves metabolically labeling cells with radioactive amino acids followed by lysis in a microtubule-stabilizing buffer, centrifugation to separate soluble from polymerized tubulin, resolution of the proteins in each(More)
We previously described the isolation of Tax 18 and Tax 11-6, two paclitaxel-dependent cell lines that assemble low amounts of microtubule polymer and require the drug for cell division. In the present studies, fluorescence time-lapse microscopy was used to measure microtubule dynamic instability behavior in these cells. The mutations were found to cause(More)
To study the effects of microtubule-associated proteins (MAPs) on in vivo microtubule assembly, cDNAs containing the complete coding sequences of a Drosophila 205-kD heat stable MAP, human MAP 4, and human tau were stably transfected into CHO cells. Constitutive expression of the transfected genes was low in most cases and had no obvious effects on the(More)
Vertebrate tubulin is encoded by a multigene family that produces distinct gene products, or isotypes, of both the alpha- and beta-tubulin subunits. The isotype sequences are conserved across species supporting the hypothesis that different isotypes subserve different functions. To date, however, most studies have demonstrated that tubulin isotypes are(More)
Eight strains of Chinese hamster ovary (CHO) cells having an assembly-defective beta-tubulin were found among revertants of strain Cmd 4, a mutant with a conditional lethal mutation in a beta-tubulin gene (F. Cabral, M. E. Sobel, and M. M. Gottesman, Cell 20:29-36, 1980). The altered beta-tubulins in these strains have electrophoretically silent alterations(More)
Previous research showed that mutations in β1-tubulin are frequently involved in paclitaxel resistance but the question of whether the mutations are restricted by cell-type specific differences remains obscure. To circumvent cellular constraints, we randomly mutagenized β-tubulin cDNA, transfected it into CHO cells, and selected for paclitaxel resistance. A(More)
Two Chinese hamster ovary cell lines with mutated beta-tubulins (Grs-2 and Cmd-4) and one that has a mutation in alpha-tubulin (Tax-1) are temperature sensitive for growth at 40.5 degrees C. To determine the functional defect in these mutant cells at the nonpermissive temperature, they were characterized with respect to cell cycle parameters and microtubule(More)
Single-step mutants of Chinese hamster ovary (CHO) cells have been isolated which are resistant to killing by the anti-mitotic drugs colchicine, colcemid or griseofulvin. Two-dimensional gel analysis showed that two mutants resistant to griseofulvin, one resistant to colcemid and one resistant to colchicine carry an alteration in the beta-tubulin subunit.(More)
Analysis of beta-tubulin alleles from nine paclitaxel-resistant Chinese hamster ovary cell lines revealed an unexpected cluster of mutations affecting Leu-215, Leu-217, and Leu-228. Six of the mutant alleles encode a His, Arg, or Phe substitution at Leu-215; another mutant allele has an Arg substitution at Leu-217; and the final two mutant alleles have(More)
Despite an intensive search, few water-soluble paclitaxel derivatives have been shown to have a therapeutic index superior to paclitaxel itself. We now report a water-soluble poly(L-glutamic acid)-paclitaxel conjugate (PG-TXL) that produces striking antitumor effects with diminished toxicity. A single i.v. injection of PG-TXL at its maximum tolerated dose(More)