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bioRxiv · 10.1101/2024.09.11.612465

EB-SUN, a New Microtubule Plus-End Tracking Protein in Drosophila.

Kim, S. K.·Rogers, S.·Lu, W.·Lee, B. S.·Gelfand, V. I.
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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 StatementO_LIOur 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. C_LIO_LIWe demonstrate the functional redundancy of EB-SUN and EB1 during oocyte development, while highlighting their distinct roles in early embryogenesis. C_LIO_LIGiven 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. C_LI

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Kim, S. K., Rogers, S., Lu, W., Lee, B. S., Gelfand, V. I.. 2024-09-11. EB-SUN, a New Microtubule Plus-End Tracking Protein in Drosophila.. https://doi.org/10.1101/2024.09.11.612465

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