The Microcephaly-Associated Protein Wdr62/CG7337 Is Required to Maintain Centrosome Asymmetry in Drosophila Neuroblasts

Anjana Ramdas Nair,David Salvador Garcia,David Rodriguez-Crespo,Boris Egger,Priyanka Singh,Clemens Cabernard

doi:10.1016/j.celrep.2015.12.097

Anjana Ramdas Nair, David Salvador Garcia + Show 4 more

Open Access

https://doi.org/10.1016/j.celrep.2015.12.097

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Journal: Cell Reports	Publication Date: Jan 21, 2016
Citations: 87	License type: cc-by

Affiliation: University of Basel, University of Fribourg

Abstract

Centrosome asymmetry has been implicated in stem cell fate maintenance in both flies and vertebrates, but the underlying molecular mechanisms are incompletely understood. Here, we report that loss of CG7337, the fly ortholog of WDR62, compromises interphase centrosome asymmetry in fly neural stem cells (neuroblasts). Wdr62 maintains an active interphase microtubule-organizing center (MTOC) by stabilizing microtubules (MTs), which are necessary for sustained recruitment of Polo/Plk1 to the pericentriolar matrix (PCM) and downregulation of Pericentrin-like protein (Plp). The loss of an active MTOC in wdr62 mutants compromises centrosome positioning, spindle orientation, and biased centrosome segregation. wdr62 mutant flies also have an ∼40% reduction in brain size as a result of cell-cycle delays. We propose that CG7337/Wdr62, a microtubule-associated protein, is required for the maintenance of interphase microtubules, thereby regulating centrosomal Polo and Plp levels. Independent of this function, Wdr62 is also required for the timely mitotic entry of neural stem cells.

Highlights

Figure S4: microtubules are required to maintain Polo and Cnn on the apical interphase centrosome, related to Figure 4 (A) Representative zeste-white 10 mutant neuroblasts expressing Polo::GFP and the MTOC marker Jupiter::mCherry or (C) Cnn::mCherry exposed to low doses of colcemid. (B) Representative control image sequence of a zeste-white 10 mutant neuroblast expressing Polo::GFP and the PCM marker Cnn::mCherry
Contrast and brightness has been adjusted for better visibility
Detection and counting of neuroblasts: We dissected carefully staged wild type, cnb RNAi expressing (v28651; VDRC) and wdr62Δ2a mutant third instar larvae (120h after egg laying) and stained with the neuroblast markers Deadpan (Dpn) and Discs large 1 (Dlg1)

Summary

Introduction

Figure S4: microtubules are required to maintain Polo and Cnn on the apical interphase centrosome, related to Figure 4 (A) Representative zeste-white 10 mutant neuroblasts expressing Polo::GFP and the MTOC marker Jupiter::mCherry or (C) Cnn::mCherry exposed to low doses of colcemid. (B) Representative control image sequence of a zeste-white 10 mutant neuroblast expressing Polo::GFP (top row) and the PCM marker Cnn::mCherry (bottom row). Thin lines represent individual neuroblasts (blue; wild type, green; wdr62 mutants) and the thicker bar on top denotes the average cell cycle time.

Results

Conclusion