α4-Tubulin is involved in rapid formation of long microtubules to push apart the daughter centrosomes during early Drosophila embryogenesis

Zsolt Venkel, Imre Gáspár, Gábor Tóth, János Szabad

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Although α 4-tubulin comprises only about one-fifth of the α-tubulin pool in every Drosophila egg, in the absence of α4-tubulin - in eggs of the kavar0/- hemizygous females - only a tassel of short microtubules forms with two barely separated daughter centrosomes. We report that α4-tubulin is enriched in the long microtubules that embrace the nuclear envelope and suggest that they push apart daughter centrosomes along the nuclear perimeter during the initial cleavage divisions. In vitro tubulin polymerization showed that α4-tubulin is required for rapid tubulin polymerization. Since tubulin polymerization is slow inside eggs of the kavar0/- females, only short microtubules can form within the 4 to 5 minutes allowed for the process. A tassel of short microtubules with two barely separated centrosomes forms in every egg of the Kavar18c/+ females, in which the cytoplasm contains both wild-type and Kavar18c-encoded α4-tubulin with an E82K amino acid substitution (E82K-α4-tubulin). E82K-α4-tubulin is incorporated into the microtubules and renders them unstable. When injected into wild-type early cleavage embryos E82K-α4-tubulin slows down the formation of long microtubules and the separation of the daughter centrosomes. Surprisingly, when injected into late cleavage embryos E82K-α4-tubulin is non-toxic. Similarly, in the neuroblasts, ectopically expressed E82K-α4-tubulin becomes incorporated into the microtubules that grow sufficiently long and function normally.

Original languageEnglish
Pages (from-to)3238-3248
Number of pages11
JournalJournal of cell science
Volume119
Issue number15
DOIs
Publication statusPublished - Aug 1 2006

Keywords

  • Centrosome separation
  • Dominant-negative mutation
  • Drosophila embryogenesis
  • Interpolar microtubules
  • α-tubulin

ASJC Scopus subject areas

  • Cell Biology

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