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Rylee J, Mahato S, Aldrich J, Bergh E, Sizemore B, Feder LE, Grega S, Helms K, Maar M, Britt SG, Zelhof AC. A TRiP RNAi screen to identify molecules necessary for Drosophila photoreceptor differentiation. G3 Genes|Genomes|Genetics 2022; 12:6758253. [DOI: 10.1093/g3journal/jkac257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 09/15/2022] [Indexed: 11/06/2022]
Abstract
Abstract
Drosophila rhabdomeric terminal photoreceptor differentiation is an extended process taking several days to complete. Following ommatidial patterning by the morphogenetic furrow, photoreceptors are sequentially recruited and specified, and terminal differentiation begins. Key events of terminal differentiation include the establishment of apical and basolateral domains, rhabdomere and stalk formation, inter-rhabdomeral space formation, and expression of phototransduction machinery. While many key regulators of these processes have been identified, the complete network of transcription factors to downstream effector molecules necessary for regulating each of these major events remains incomplete. Here, we report an RNAi screen to identify additional molecules and cellular pathways required for photoreceptor terminal differentiation. First, we tested several eye-specific GAL4 drivers for correct spatial and temporal specificity and identified Pph13-GAL4 as the most appropriate GAL4 line for our screen. We screened lines available through the Transgenic RNAi Project and isolated lines that when combined with Pph13-GAL4 resulted in the loss of the deep pseudopupil, as a readout for abnormal differentiation. In the end, we screened 6,189 lines, representing 3,971 genes, and have identified 64 genes, illuminating potential new regulatory molecules and cellular pathways for the differentiation and organization of Drosophila rhabdomeric photoreceptors.
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Affiliation(s)
- Johnathan Rylee
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Simpla Mahato
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - John Aldrich
- Department of Neurology and Ophthalmology, Dell Medical School, University of Texas , Austin, TX 78712, USA
| | - Emma Bergh
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Brandon Sizemore
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Lauren E Feder
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Shaun Grega
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Kennedy Helms
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Megan Maar
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
| | - Steven G Britt
- Department of Neurology and Ophthalmology, Dell Medical School, University of Texas , Austin, TX 78712, USA
| | - Andrew C Zelhof
- Department of Biology, Indiana University , Bloomington, IN 47405, USA
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Zelhof AC, Mahato S, Liang X, Rylee J, Bergh E, Feder LE, Larsen ME, Britt SG, Friedrich M. The brachyceran de novo gene PIP82, a phosphorylation target of aPKC, is essential for proper formation and maintenance of the rhabdomeric photoreceptor apical domain in Drosophila. PLoS Genet 2020; 16:e1008890. [PMID: 32579558 PMCID: PMC7340324 DOI: 10.1371/journal.pgen.1008890] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 07/07/2020] [Accepted: 05/27/2020] [Indexed: 11/18/2022] Open
Abstract
The Drosophila apical photoreceptor membrane is defined by the presence of two distinct morphological regions, the microvilli-based rhabdomere and the stalk membrane. The subdivision of the apical membrane contributes to the geometrical positioning and the stereotypical morphology of the rhabdomeres in compound eyes with open rhabdoms and neural superposition. Here we describe the characterization of the photoreceptor specific protein PIP82. We found that PIP82's subcellular localization demarcates the rhabdomeric portion of the apical membrane. We further demonstrate that PIP82 is a phosphorylation target of aPKC. PIP82 localization is modulated by phosphorylation, and in vivo, the loss of the aPKC/Crumbs complex results in an expansion of the PIP82 localization domain. The absence of PIP82 in photoreceptors leads to misshapped rhabdomeres as a result of misdirected cellular trafficking of rhabdomere proteins. Comparative analyses reveal that PIP82 originated de novo in the lineage leading to brachyceran Diptera, which is also characterized by the transition from fused to open rhabdoms. Taken together, these findings define a novel factor that delineates and maintains a specific apical membrane domain, and offers new insights into the functional organization and evolutionary history of the Drosophila retina.
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Affiliation(s)
- Andrew C. Zelhof
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Simpla Mahato
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Xulong Liang
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Jonathan Rylee
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Emma Bergh
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Lauren E. Feder
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Matthew E. Larsen
- Department of Neurology and Ophthalmology, Dell Medical School, University of Texas, Austin, Texas, United States of America
| | - Steven G. Britt
- Department of Neurology and Ophthalmology, Dell Medical School, University of Texas, Austin, Texas, United States of America
| | - Markus Friedrich
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
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