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The Shot CH1 domain recognises a distinct form of F-actin during Drosophila oocyte determination

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Peer-reviewed

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Authors

Squires, Iolo 
St Johnston, Daniel  ORCID logo  https://orcid.org/0000-0001-5582-3301

Abstract

In Drosophila, only one cell in a multicellular female germline cyst is specified as an oocyte and a similar process occurs in mammals. The symmetry-breaking cue for oocyte selection is provided by the fusome, a tubular structure connecting all cells in the cyst. The Drosophila spectraplakin Shot localises to the fusome and translates its asymmetry into a polarised microtubule network that is essential for oocyte specification, but how Shot recognises the fusome is unclear. Here, we demonstrate that the actin-binding domain (ABD) of Shot is necessary and sufficient to localise Shot to the fusome and mediates Shot function in oocyte specification together with the microtubule-binding domains. The calponin homology domain 1 of the Shot ABD recognises fusomal F-actin and requires calponin homology domain 2 to distinguish it from other forms of F-actin in the cyst. By contrast, the ABDs of utrophin, Fimbrin, Filamin, Lifeact and F-tractin do not recognise fusomal F-actin. We therefore propose that Shot propagates fusome asymmetry by recognising a specific conformational state of F-actin on the fusome.

Description

Peer reviewed: True


Acknowledgements: We are grateful to Jean-René Huynh, Christian Klämbt, Thomas Lecuit, Katja Röper and the Bloomington Drosophila Stock Center (NIH P40OD018537) for fly stocks; Nicola Lawrence at the Gurdon Institute Imaging Facility for assistance with microscopy; and John Overton for technical assistance in making transgenic flies.


Publication status: Published


Funder: Wellcome; doi: http://dx.doi.org/10.13039/100010269


Funder: University of Cambridge; doi: http://dx.doi.org/10.13039/501100000735

Keywords

Calponin homology domain, Cell polarity, Spectraplakin, Gametogenesis, Germ cell, Cytoskeleton

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Publisher

The Company of Biologists Ltd
Sponsorship
Wellcome (080007, 203144, 092096, 207496)
Cancer Research UK (A14492, A24823)
Biotechnology and Biological Sciences Research Council (BB/R001618/1, BB/M007553/1, BB/I002448/1, BB/C515998/1)