1
|
Multiple Requirements for Rab GTPases in the Development of Drosophila Tracheal Dorsal Branches and Terminal Cells. G3-GENES GENOMES GENETICS 2020; 10:1099-1112. [PMID: 31980432 PMCID: PMC7056964 DOI: 10.1534/g3.119.400967] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The tracheal epithelium in fruit fly larvae is a popular model for multi- and unicellular migration and morphogenesis. Like all epithelial cells, tracheal cells use Rab GTPases to organize their internal membrane transport, resulting in the specific localization or secretion of proteins on the apical or basal membrane compartments. Some contributions of Rabs to junctional remodelling and governance of tracheal lumen contents are known, but it is reasonable to assume that they play important further roles in morphogenesis. This pertains in particular to terminal tracheal cells, specialized branch-forming cells that drastically reshape both their apical and basal membrane during the larval stages. We performed a loss-of-function screen in the tracheal system, knocking down endogenously tagged alleles of 26 Rabs by targeting the tag via RNAi. This revealed that at least 14 Rabs are required to ensure proper cell fate specification and migration of the dorsal branches, as well as their epithelial fusion with the contralateral dorsal branch. The screen implicated four Rabs in the subcellular morphogenesis of terminal cells themselves. Further tests suggested residual gene function after knockdown, leading us to discuss the limitations of this approach. We conclude that more Rabs than identified here may be important for tracheal morphogenesis, and that the tracheal system offers great opportunities for studying several Rabs that have barely been characterized so far.
Collapse
|
2
|
Yao L, Wang S, Westholm JO, Dai Q, Matsuda R, Hosono C, Bray S, Lai EC, Samakovlis C. Genome-wide identification of Grainy head targets in Drosophila reveals regulatory interactions with the POU domain transcription factor Vvl. Development 2017; 144:3145-3155. [PMID: 28760809 DOI: 10.1242/dev.143297] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 07/21/2017] [Indexed: 12/17/2022]
Abstract
Grainy head (Grh) is a conserved transcription factor (TF) controlling epithelial differentiation and regeneration. To elucidate Grh functions we identified embryonic Grh targets by ChIP-seq and gene expression analysis. We show that Grh controls hundreds of target genes. Repression or activation correlates with the distance of Grh-binding sites to the transcription start sites of its targets. Analysis of 54 Grh-responsive enhancers during development and upon wounding suggests cooperation with distinct TFs in different contexts. In the airways, Grh-repressed genes encode key TFs involved in branching and cell differentiation. Reduction of the POU domain TF Ventral veins lacking (Vvl) largely ameliorates the airway morphogenesis defects of grh mutants. Vvl and Grh proteins additionally interact with each other and regulate a set of common enhancers during epithelial morphogenesis. We conclude that Grh and Vvl participate in a regulatory network controlling epithelial maturation.
Collapse
Affiliation(s)
- Liqun Yao
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, S10691, Stockholm, Sweden
| | - Shenqiu Wang
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, S10691, Stockholm, Sweden.,Cancer Biology & Genetics Program, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York, NY 10065, USA
| | - Jakub O Westholm
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York, NY 10065, USA.,Science for Life Laboratory, Tomtebodavägen 232, 171 21 Solna, Sweden
| | - Qi Dai
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, S10691, Stockholm, Sweden.,Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York, NY 10065, USA
| | - Ryo Matsuda
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, S10691, Stockholm, Sweden
| | - Chie Hosono
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, S10691, Stockholm, Sweden
| | - Sarah Bray
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Eric C Lai
- Department of Developmental Biology, Sloan-Kettering Institute, 1275 York Ave, Box 252, New York, NY 10065, USA
| | - Christos Samakovlis
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, S10691, Stockholm, Sweden .,Science for Life Laboratory, Tomtebodavägen 232, 171 21 Solna, Sweden.,Molecular Pneumology, UGMLC, Aulweg 130, 35392 Giessen, Germany
| |
Collapse
|