
==== Front
bioRxiv
BIORXIV
bioRxiv
2692-8205
Cold Spring Harbor Laboratory

10.1101/2024.09.11.612465
preprint
1
Article
EB-SUN, a New Microtubule Plus-End Tracking Protein in Drosophila
Kim Sun K.
Rogers Stephen L.
Lu Wen
Lee Brad S.
Gelfand Vladimir I. http://orcid.org/0000-0002-6361-2798

11 9 2024
2024.09.11.612465https://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which allows reusers to copy and distribute the material in any medium or format in unadapted form only, for noncommercial purposes only, and only so long as attribution is given to the creator.
http://biorxiv.org/lookup/doi/10.1101/2024.09.11.612465
nihpp-2024.09.11.612465.pdf
Abstract

Microtubule (MT) regulation is essential for oocyte development. In Drosophila , MT stability, polarity, abundance, and orientation undergo dynamic changes across developmental stages. In our effort to identify novel microtubule-associated proteins (MAPs) that regulate MTs in the Drosophila ovary, we identified a previously uncharacterized gene, CG18190, encoding a novel MT end-binding (EB) protein, which we propose to name EB-SUN. We show that EB-SUN colocalizes with EB1 at growing microtubule plus-ends in Drosophila S2 cells. Tissue-specific and developmental expression profiles from Paralog Explorer reveal that EB-SUN is predominantly expressed in the ovary and early embryos, while EB1 is ubiquitously expressed. Furthermore, as early as oocyte determination, EB-SUN comets are highly concentrated in oocytes during oogenesis. EB-SUN knockout (KO) results in a decrease in MT density at the onset of mid-oogenesis (Stage 7) and delays oocyte growth during late mid-oogenesis (Stage 9). Combining EB-SUN KO with EB1 knockdown (KD) in germ cells significantly further reduced MT density at Stage 7. Notably, all eggs from EB-SUN KO/EB1 KD females fail to hatch, unlike single gene depletion, suggesting a functional redundancy between these two EB proteins during embryogenesis. Our findings indicate that EB-SUN and EB1 play distinct roles during early embryogenesis.

Significance Statement

Our study identified a novel microtubule end-binding (EB) protein, which is highly expressed in the Drosophila ovary, and we propose to name it EB-SUN.

We demonstrate the functional redundancy of EB-SUN and EB1 during oocyte development, while highlighting their distinct roles in early embryogenesis.

Given the high conservation of MT-dependent mechanisms in oogenesis and EB proteins across species, these findings provide insights into the differential regulation and tissue-specific functions of the EB family, using Drosophila as a model system, potentially benefiting future research on MT regulation in higher organisms.
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