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Asymmetrically dividing Drosophila neuroblasts utilize two spatially and temporally independent cytokinesis pathways.

Roth M, Roubinet C, Iffländer N, Ferrand A, Cabernard C - Nat Commun (2015)

Bottom Line: In most metazoan cells, contractile ring placement is regulated by the mitotic spindle through the centralspindlin complex, and potentially also the chromosomal passenger complex (CPC).Drosophila neuroblasts, asymmetrically dividing neural stem cells, but also other cells utilize both spindle-dependent and spindle-independent cleavage furrow positioning pathways.However, the relative contribution of each pathway towards cytokinesis is currently unclear.

View Article: PubMed Central - PubMed

Affiliation: Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland.

ABSTRACT
Precise cleavage furrow positioning is required for faithful chromosome segregation and cell fate determinant distribution. In most metazoan cells, contractile ring placement is regulated by the mitotic spindle through the centralspindlin complex, and potentially also the chromosomal passenger complex (CPC). Drosophila neuroblasts, asymmetrically dividing neural stem cells, but also other cells utilize both spindle-dependent and spindle-independent cleavage furrow positioning pathways. However, the relative contribution of each pathway towards cytokinesis is currently unclear. Here we report that in Drosophila neuroblasts, the mitotic spindle, but not polarity cues, controls the localization of the CPC component Survivin. We also show that Survivin and the mitotic spindle are required to stabilize the position of the cleavage furrow in late anaphase and to complete furrow constriction. These results support the model that two spatially and temporally separate pathways control different key aspects during asymmetric cell division, ensuring correct cell fate determinant segregation and neuroblast self-renewal.

No MeSH data available.


Related in: MedlinePlus

Survivin is required for cleavage furrow constriction.(a) Image sequence of a representative wild-type neuroblast expressing Sqh::GFP (green in overlay) and mCherry::Jupiter (white in overlay). (b) Quantification of wild-type neuroblast diameter measurements. (c) Constriction rates of wild-type neuroblasts. Averages and s.d. are shown (n=11). (d) Image sequence of a representative scpoz2775/Df(3R)5780 mutant neuroblast expressing Sqh::GFP (green in overlay) and mCherry::Jupiter. (e) Diameter measurements. The grey dashed line indicates the minimal diameter. (f) Corresponding constriction rates of scpoz2775/Df(3R)5780 mutant neuroblasts (n=8). Time in min:s; scale bar, 5 μm.
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f5: Survivin is required for cleavage furrow constriction.(a) Image sequence of a representative wild-type neuroblast expressing Sqh::GFP (green in overlay) and mCherry::Jupiter (white in overlay). (b) Quantification of wild-type neuroblast diameter measurements. (c) Constriction rates of wild-type neuroblasts. Averages and s.d. are shown (n=11). (d) Image sequence of a representative scpoz2775/Df(3R)5780 mutant neuroblast expressing Sqh::GFP (green in overlay) and mCherry::Jupiter. (e) Diameter measurements. The grey dashed line indicates the minimal diameter. (f) Corresponding constriction rates of scpoz2775/Df(3R)5780 mutant neuroblasts (n=8). Time in min:s; scale bar, 5 μm.

Mentions: We performed live imaging on wild-type (Supplementary Movie 4) and scpoZ2775/Df(3R)5780 (Supplementary Movie 5) mutant larval neuroblasts, expressing Sqh::GFP27 and mCherry::Jupiter,11 and first measured furrow constriction dynamics (see Methods). Using anaphase onset as a reference point, we found that wild-type neuroblasts completed constriction on average within 7.4 min (mean=464 s; s.d.=94 s; n=11; Fig. 5a,b; Table 1). We further calculated constriction rates and found that wild-type neuroblasts showed three distinct furrowing phases: constriction started slow, increased in speed and then slowed down again towards the end of cytokinesis (Fig. 5c). scpo mutant neuroblasts reached a minimal diameter of roughly 4.6 μm (s.d.=1.4 μm; n=8) on average in 8.4 min (mean=503 s; s.d.=118 s; n=8; Fig. 5d,e; Table 1) but then reopened the cleavage furrow. scpo mutant neuroblasts only contained a single slow constriction phase (Fig. 5f). We conclude that scpo is required for efficient cleavage furrow constriction and completion of cytokinesis. Furthermore, since dlg, pins single and dlg;;pins double mutants always complete cytokinesis (data not shown and ref. 11), Survivin’s role during cytokinesis seems distinct from the polarity-dependent cytokinesis pathway.


Asymmetrically dividing Drosophila neuroblasts utilize two spatially and temporally independent cytokinesis pathways.

Roth M, Roubinet C, Iffländer N, Ferrand A, Cabernard C - Nat Commun (2015)

Survivin is required for cleavage furrow constriction.(a) Image sequence of a representative wild-type neuroblast expressing Sqh::GFP (green in overlay) and mCherry::Jupiter (white in overlay). (b) Quantification of wild-type neuroblast diameter measurements. (c) Constriction rates of wild-type neuroblasts. Averages and s.d. are shown (n=11). (d) Image sequence of a representative scpoz2775/Df(3R)5780 mutant neuroblast expressing Sqh::GFP (green in overlay) and mCherry::Jupiter. (e) Diameter measurements. The grey dashed line indicates the minimal diameter. (f) Corresponding constriction rates of scpoz2775/Df(3R)5780 mutant neuroblasts (n=8). Time in min:s; scale bar, 5 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4544045&req=5

f5: Survivin is required for cleavage furrow constriction.(a) Image sequence of a representative wild-type neuroblast expressing Sqh::GFP (green in overlay) and mCherry::Jupiter (white in overlay). (b) Quantification of wild-type neuroblast diameter measurements. (c) Constriction rates of wild-type neuroblasts. Averages and s.d. are shown (n=11). (d) Image sequence of a representative scpoz2775/Df(3R)5780 mutant neuroblast expressing Sqh::GFP (green in overlay) and mCherry::Jupiter. (e) Diameter measurements. The grey dashed line indicates the minimal diameter. (f) Corresponding constriction rates of scpoz2775/Df(3R)5780 mutant neuroblasts (n=8). Time in min:s; scale bar, 5 μm.
Mentions: We performed live imaging on wild-type (Supplementary Movie 4) and scpoZ2775/Df(3R)5780 (Supplementary Movie 5) mutant larval neuroblasts, expressing Sqh::GFP27 and mCherry::Jupiter,11 and first measured furrow constriction dynamics (see Methods). Using anaphase onset as a reference point, we found that wild-type neuroblasts completed constriction on average within 7.4 min (mean=464 s; s.d.=94 s; n=11; Fig. 5a,b; Table 1). We further calculated constriction rates and found that wild-type neuroblasts showed three distinct furrowing phases: constriction started slow, increased in speed and then slowed down again towards the end of cytokinesis (Fig. 5c). scpo mutant neuroblasts reached a minimal diameter of roughly 4.6 μm (s.d.=1.4 μm; n=8) on average in 8.4 min (mean=503 s; s.d.=118 s; n=8; Fig. 5d,e; Table 1) but then reopened the cleavage furrow. scpo mutant neuroblasts only contained a single slow constriction phase (Fig. 5f). We conclude that scpo is required for efficient cleavage furrow constriction and completion of cytokinesis. Furthermore, since dlg, pins single and dlg;;pins double mutants always complete cytokinesis (data not shown and ref. 11), Survivin’s role during cytokinesis seems distinct from the polarity-dependent cytokinesis pathway.

Bottom Line: In most metazoan cells, contractile ring placement is regulated by the mitotic spindle through the centralspindlin complex, and potentially also the chromosomal passenger complex (CPC).Drosophila neuroblasts, asymmetrically dividing neural stem cells, but also other cells utilize both spindle-dependent and spindle-independent cleavage furrow positioning pathways.However, the relative contribution of each pathway towards cytokinesis is currently unclear.

View Article: PubMed Central - PubMed

Affiliation: Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland.

ABSTRACT
Precise cleavage furrow positioning is required for faithful chromosome segregation and cell fate determinant distribution. In most metazoan cells, contractile ring placement is regulated by the mitotic spindle through the centralspindlin complex, and potentially also the chromosomal passenger complex (CPC). Drosophila neuroblasts, asymmetrically dividing neural stem cells, but also other cells utilize both spindle-dependent and spindle-independent cleavage furrow positioning pathways. However, the relative contribution of each pathway towards cytokinesis is currently unclear. Here we report that in Drosophila neuroblasts, the mitotic spindle, but not polarity cues, controls the localization of the CPC component Survivin. We also show that Survivin and the mitotic spindle are required to stabilize the position of the cleavage furrow in late anaphase and to complete furrow constriction. These results support the model that two spatially and temporally separate pathways control different key aspects during asymmetric cell division, ensuring correct cell fate determinant segregation and neuroblast self-renewal.

No MeSH data available.


Related in: MedlinePlus