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γ-Tubulin small complex formation is essential for early zebrafish embryogenesis

Authors: 
Pouchucq L, Undurraga CA, Fuentes R, Cornejo M, Allende ML, Monasterio O
Citation: 
Mech Dev. 2018 Jul 3. pii: S0925-4773(18)30061-3. doi: 10.1016/j.mod.2018.06.006. [Epub ahead of print]
Abstract: 
The centrosomal protein γ-tubulin is part of the cytoplasmic γ-tubulin small (γ-TuSCs) and large complexes (γ-TuRCs). Both, molecular and cellular evidence indicate that γ-tubulin plays a central role in microtubule nucleation and mitotic spindle formation. However, the molecular mechanisms of complex formation and subsequent biological roles in animal development remain unclear. Here, we used γ-tubulin gene knockdown in the zebrafish early embryo model to gain insights into its activity and cellular contribution during vertebrate embryogenesis. γ-Tubulin loss-of-function impaired γ-TuSC formation, impacting the microtubule nucleation rate in vitro. Moreover, decreased γ-tubulin synthesis caused dramatic defects in nuclear dynamics and cell cycle progression, leading to developmental arrest at the mid-gastrula stage. At the subcellular level, microtubule organization and function were altered, affecting chromosome segregation and triggering cell proliferation arrest and apoptosis. Our results suggest that de novo translated γ-tubulin participates in γ-TuSC formation required for early animal development. Importantly, formation of this complex is essential for both centrosome assembly and function, and cell proliferation. Thus, γ-TuSC integrity appears to be critical for cell cycle progression, and concomitantly, for coordinating the many distinct activities carried out by the early embryo. Our findings identify a novel role for γ-TuSC in the regulation of early vertebrate embryogenesis, providing molecular and biochemical starting points for future in depth studies of γ-tubulin functionality and its specific role in development.
Epub: 
Yes
Organism or Cell Type: 
zebrafish