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The Protein O-glucosyltransferase Rumi Modifies Eyes Shut to Promote Rhabdomere Separation in Drosophila

Haltom, AR and Lee, TV and Harvey, BM and Leonardi, J and Chen, YJ and Hong, Y and Haltiwanger, RS and Jafar-Nejad, H (2014) The Protein O-glucosyltransferase Rumi Modifies Eyes Shut to Promote Rhabdomere Separation in Drosophila. PLoS Genetics, 10 (11). ISSN 1553-7390

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Abstract

The protein O-glucosyltransferase Rumi/POGLUT1 regulates Drosophila Notch signaling by adding O-glucose residues to the Notch extracellular domain. Rumi has other predicted targets including Crumbs (Crb) and Eyes shut (Eys), both of which are involved in photoreceptor development. However, whether Rumi is required for the function of Crb and Eys remains unknown. Here we report that in the absence of Rumi or its enzymatic activity, several rhabdomeres in each ommatidium fail to separate from one another in a Notch-independent manner. Mass spectral analysis indicates the presence of O-glucose on Crb and Eys. However, mutating all O-glucosylation sites in a crb knock-in allele does not cause rhabdomere attachment, ruling out Crb as a biologically-relevant Rumi target in this process. In contrast, eys and rumi exhibit a dosage-sensitive genetic interaction. In addition, although in wild-type ommatidia most of the Eys protein is found in the inter-rhabdomeral space (IRS), in rumi mutants a significant fraction of Eys remains in the photoreceptor cells. The intracellular accumulation of Eys and the IRS defect worsen in rumi mutants raised at a higher temperature, and are accompanied by a ∼50% decrease in the total level of Eys. Moreover, removing one copy of an endoplasmic reticulum chaperone enhances the rhabdomere attachment in rumi mutant animals. Altogether, our data suggest that O-glucosylation of Eys by Rumi ensures rhabdomere separation by promoting proper Eys folding and stability in a critical time window during the mid-pupal stage. Human EYS, which is mutated in patients with autosomal recessive retinitis pigmentosa, also harbors multiple Rumi target sites. Therefore, the role of O-glucose in regulating Eys may be conserved.

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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Haltom, AR
Lee, TV
Harvey, BM
Leonardi, J
Chen, YJ
Hong, Yyhong@pitt.eduYHONG
Haltiwanger, RS
Jafar-Nejad, H
Contributors:
ContributionContributors NameEmailPitt UsernameORCID
EditorNorbert, PerrimonUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Date: 1 November 2014
Date Type: Publication
Journal or Publication Title: PLoS Genetics
Volume: 10
Number: 11
DOI or Unique Handle: 10.1371/journal.pgen.1004795
Schools and Programs: School of Medicine > Cell Biology
Refereed: Yes
ISSN: 1553-7390
Other ID: NLM PMC4238978
PubMed Central ID: PMC4238978
PubMed ID: 25412384
Date Deposited: 12 May 2015 18:35
Last Modified: 12 Nov 2021 20:55
URI: http://d-scholarship.pitt.edu/id/eprint/24067

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