Filopodia-like Actin Cables Position Nuclei in Association with Perinuclear Actin in Drosophila Nurse Cells

Summary

Controlling the position of the nucleus is vital for a number of cellular processes from yeast to humans. In Drosophila nurse cells, nuclear positioning is crucial during dumping, when nurse cells contract and expel their contents into the oocyte. We provide evidence that in nurse cells, continuous filopodia-like actin cables, growing from the plasma membrane and extending to the nucleus, achieve nuclear positioning. These actin cables move nuclei away from ring canals. When nurse cells contract, actin cables associate laterally with the nuclei, in some cases inducing nuclear turning so that actin cables become partially wound around the nuclei. Our data suggest that a perinuclear actin meshwork connects actin cables to nuclei via actin-crosslinking proteins such as the filamin Cheerio. We provide a revised model for how actin structures position nuclei in nurse cells, employing evolutionary conserved machinery.

Graphical Abstract

Highlights

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  Actin cables in Drosophila nurse cells are unsegmented filopodia-like structures

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  E-cadherin is required for the orientation of actin cables toward the nucleus

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  Nuclear positioning is achieved by continuous elongation of actin cables

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  Actin cables associate with perinuclear actin-containing crosslinkers like filamin

Abstract

Huelsmann et al. propose a nuclear positioning model by visualizing the interplay between actin structures as Drosophila nurse cells contract to expel their contents. Filopodia-like actin cables grow from the plasma membrane, connect with an actin meshwork surrounding the nucleus, and push nuclei out of the path of cytoplasmic flow.