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Benner L, Muron S, Gomez JG, Oliver B. OVO positively regulates essential maternal pathways by binding near the transcriptional start sites in the Drosophila female germline. eLife 2024; 13:RP94631. [PMID: 39291827 PMCID: PMC11410370 DOI: 10.7554/elife.94631] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2024] Open
Abstract
Differentiation of female germline stem cells into a mature oocyte includes the expression of RNAs and proteins that drive early embryonic development in Drosophila. We have little insight into what activates the expression of these maternal factors. One candidate is the zinc-finger protein OVO. OVO is required for female germline viability and has been shown to positively regulate its own expression, as well as a downstream target, ovarian tumor, by binding to the transcriptional start site (TSS). To find additional OVO targets in the female germline and further elucidate OVO's role in oocyte development, we performed ChIP-seq to determine genome-wide OVO occupancy, as well as RNA-seq comparing hypomorphic and wild type rescue ovo alleles. OVO preferentially binds in close proximity to target TSSs genome-wide, is associated with open chromatin, transcriptionally active histone marks, and OVO-dependent expression. Motif enrichment analysis on OVO ChIP peaks identified a 5'-TAACNGT-3' OVO DNA binding motif spatially enriched near TSSs. However, the OVO DNA binding motif does not exhibit precise motif spacing relative to the TSS characteristic of RNA polymerase II complex binding core promoter elements. Integrated genomics analysis showed that 525 genes that are bound and increase in expression downstream of OVO are known to be essential maternally expressed genes. These include genes involved in anterior/posterior/germ plasm specification (bcd, exu, swa, osk, nos, aub, pgc, gcl), egg activation (png, plu, gnu, wisp, C(3)g, mtrm), translational regulation (cup, orb, bru1, me31B), and vitelline membrane formation (fs(1)N, fs(1)M3, clos). This suggests that OVO is a master transcriptional regulator of oocyte development and is responsible for the expression of structural components of the egg as well as maternally provided RNAs that are required for early embryonic development.
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Affiliation(s)
- Leif Benner
- Section of Developmental Genomics, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Savannah Muron
- Section of Developmental Genomics, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
| | - Jillian G Gomez
- Section of Developmental Genomics, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
| | - Brian Oliver
- Section of Developmental Genomics, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
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Benner L, Muron S, Gomez JG, Oliver B. OVO Positively Regulates Essential Maternal Pathways by Binding Near the Transcriptional Start Sites in the Drosophila Female Germline. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.01.565184. [PMID: 38076814 PMCID: PMC10705541 DOI: 10.1101/2023.11.01.565184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/25/2023]
Abstract
Differentiation of female germline stem cells into a mature oocyte includes the expression of RNAs and proteins that drive early embryonic development in Drosophila. We have little insight into what activates the expression of these maternal factors. One candidate is the zinc-finger protein OVO. OVO is required for female germline viability and has been shown to positively regulate its own expression, as well as a downstream target, ovarian tumor, by binding to the transcriptional start site (TSS). To find additional OVO targets in the female germline and further elucidate OVO's role in oocyte development, we performed ChIP-seq to determine genome-wide OVO occupancy, as well as RNA-seq comparing hypomorphic and wild type rescue ovo alleles. OVO preferentially binds in close proximity to target TSSs genome-wide, is associated with open chromatin, transcriptionally active histone marks, and OVO-dependent expression. Motif enrichment analysis on OVO ChIP peaks identified a 5'-TAACNGT-3' OVO DNA binding motif spatially enriched near TSSs. However, the OVO DNA binding motif does not exhibit precise motif spacing relative to the TSS characteristic of RNA Polymerase II complex binding core promoter elements. Integrated genomics analysis showed that 525 genes that are bound and increase in expression downstream of OVO are known to be essential maternally expressed genes. These include genes involved in anterior/posterior/germ plasm specification (bcd, exu, swa, osk, nos, aub, pgc, gcl), egg activation (png, plu, gnu, wisp, C(3)g, mtrm), translational regulation (cup, orb, bru1, me31B), and vitelline membrane formation (fs(1)N, fs(1)M3, clos). This suggests that OVO is a master transcriptional regulator of oocyte development and is responsible for the expression of structural components of the egg as well as maternally provided RNAs that are required for early embryonic development.
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Affiliation(s)
- Leif Benner
- Section of Developmental Genomics, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Savannah Muron
- Section of Developmental Genomics, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jillian G Gomez
- Section of Developmental Genomics, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Brian Oliver
- Section of Developmental Genomics, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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Berg C, Sieber M, Sun J. Finishing the egg. Genetics 2024; 226:iyad183. [PMID: 38000906 PMCID: PMC10763546 DOI: 10.1093/genetics/iyad183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 09/27/2023] [Indexed: 11/26/2023] Open
Abstract
Gamete development is a fundamental process that is highly conserved from early eukaryotes to mammals. As germ cells develop, they must coordinate a dynamic series of cellular processes that support growth, cell specification, patterning, the loading of maternal factors (RNAs, proteins, and nutrients), differentiation of structures to enable fertilization and ensure embryonic survival, and other processes that make a functional oocyte. To achieve these goals, germ cells integrate a complex milieu of environmental and developmental signals to produce fertilizable eggs. Over the past 50 years, Drosophila oogenesis has risen to the forefront as a system to interrogate the sophisticated mechanisms that drive oocyte development. Studies in Drosophila have defined mechanisms in germ cells that control meiosis, protect genome integrity, facilitate mRNA trafficking, and support the maternal loading of nutrients. Work in this system has provided key insights into the mechanisms that establish egg chamber polarity and patterning as well as the mechanisms that drive ovulation and egg activation. Using the power of Drosophila genetics, the field has begun to define the molecular mechanisms that coordinate environmental stresses and nutrient availability with oocyte development. Importantly, the majority of these reproductive mechanisms are highly conserved throughout evolution, and many play critical roles in the development of somatic tissues as well. In this chapter, we summarize the recent progress in several key areas that impact egg chamber development and ovulation. First, we discuss the mechanisms that drive nutrient storage and trafficking during oocyte maturation and vitellogenesis. Second, we examine the processes that regulate follicle cell patterning and how that patterning impacts the construction of the egg shell and the establishment of embryonic polarity. Finally, we examine regulatory factors that control ovulation, egg activation, and successful fertilization.
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Affiliation(s)
- Celeste Berg
- Department of Genome Sciences, University of Washington, Seattle, WA 98195-5065USA
| | - Matthew Sieber
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390USA
| | - Jianjun Sun
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269USA
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Isoe J, Simington CJ, Oscherwitz ME, Peterson AJ, Rascón AA, Massani BB, Miesfeld RL, Riehle MA. Characterization of essential eggshell proteins from Aedes aegypti mosquitoes. BMC Biol 2023; 21:214. [PMID: 37833714 PMCID: PMC10576393 DOI: 10.1186/s12915-023-01721-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 09/29/2023] [Indexed: 10/15/2023] Open
Abstract
BACKGROUND Up to 40% of the world population live in areas where mosquitoes capable of transmitting the dengue virus, including Aedes aegypti, coexist with humans. Understanding how mosquito egg development and oviposition are regulated at the molecular level may provide new insights into novel mosquito control strategies. Previously, we identified a protein named eggshell organizing factor 1 (EOF1) that when knocked down with RNA interference (RNAi) resulted in non-melanized and fragile eggs that did not contain viable embryos. RESULTS In this current study, we performed a comprehensive RNAi screen of putative A. aegypti eggshell proteins to identify additional proteins that interact with intracellular EOF1. We identified several proteins essential for eggshell formation in A. aegypti and characterized their phenotypes through a combination of molecular and biochemical approaches. We found that Nasrat, Closca, and Polehole structural proteins, together with the Nudel serine protease, are indispensable for eggshell melanization and egg viability. While all four proteins are predominantly expressed in ovaries of adult females, Nudel messenger RNA (mRNA) expression is highly upregulated in response to blood feeding. Furthermore, we identified four additional secreted eggshell enzymes that regulated mosquito eggshell formation and melanization. These enzymes included three dopachrome-converting enzymes (DCEs) and one cysteine protease. All eight of these eggshell proteins were essential for proper eggshell formation. Interestingly, their eggshell surface topologies in response to RNAi did not phenocopy the effect of RNAi-EOF1, suggesting that additional mechanisms may influence how EOF1 regulates eggshell formation and melanization. CONCLUSIONS While our studies did not identify a definitive regulator of EOF1, we did identify eight additional proteins involved in mosquito eggshell formation that may be leveraged for future control strategies.
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Affiliation(s)
- Jun Isoe
- Department of Entomology, The University of Arizona, Tucson, AZ, 85721, USA.
| | - Carter J Simington
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721, USA
- Present address: Department of Molecular and Cellular Biology, University of California, Berkeley, Berkeley, CA94720, USA
| | - Max E Oscherwitz
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721, USA
- Present address: Heersink School of Medicine, University of Alabama, Birmingham, AL, 35233, USA
| | - Alyssa J Peterson
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721, USA
| | - Alberto A Rascón
- Department of Chemistry, San José State University, San José, CA, 95192, USA
- Present address: School of Molecular Sciences, Arizona State University, Tempe, AZ, 85281, USA
| | - Brooke B Massani
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721, USA
| | - Roger L Miesfeld
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, AZ, 85721, USA
| | - Michael A Riehle
- Department of Entomology, The University of Arizona, Tucson, AZ, 85721, USA.
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Vitelline Membrane Protein 26 Mutagenesis, Using CRISPR/Cas9, Results in Egg Collapse in Plutella xylostella. Int J Mol Sci 2022; 23:ijms23179538. [PMID: 36076934 PMCID: PMC9455775 DOI: 10.3390/ijms23179538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/13/2022] [Accepted: 08/19/2022] [Indexed: 11/16/2022] Open
Abstract
Vitelline membrane proteins (VMPs) are the main proteins that form the inner shell (vitelline membrane layer) of insect eggs and are an integral part of egg formation and embryo development. Here, we characterized the molecular structure and expression patterns of the VMP26 gene and analyzed its reproductive functions in diamondback moth, Plutella xylostella (L.), a worldwide migratory pest of cruciferous plants. The PxVMP26 gene was shown to be a single exon gene that contained an open reading frame of 852 base pairs (bp) encoding 283 amino acids. Both qPCR and western blot analyses showed that PxVMP26 was specifically expressed in female adults and was significantly highly expressed in the ovary. Further anatomical analysis indicated that the expression level of PxVMP26 in the ovarian tube with an incomplete yolk was significantly higher than that in the ovarian tube with a complete yolk. CRISPR/Cas9-induced PxVMP26 knockout successfully created two homozygous strains with 8- and 46-bp frameshift mutations. The expression deficiency of the PxVMP26 protein was detected in the mutant strains using immunofluorescence and western blot. No significant difference was found in the number of eggs laid within three days between wild and mutant individuals, but there was a lower egg hatchability. The loss of the PxVMP26 gene changed the mean egg size, damaged the structure of the vitelline membrane, and increased the proportion of abnormal eggs due to water loss, resulting in egg collapse. This first analysis of the roles of the VMP gene in the oocyte formation and embryonic development of P. xylostella, using CRISPR/Cas9 technology, provides a basis for screening new genetic control targets of P. xylostella.
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Xu X, Bi H, Wang Y, Li X, Xu J, Liu Z, He L, Li K, Huang Y. Disruption of the ovarian serine protease (Osp) gene causes female sterility in Bombyx mori and Spodoptera litura. PEST MANAGEMENT SCIENCE 2020; 76:1245-1255. [PMID: 31595658 DOI: 10.1002/ps.5634] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/13/2019] [Accepted: 07/09/2018] [Indexed: 06/10/2023]
Abstract
BACKGROUND Precise regulation of oogenesis is crucial to female reproduction. Seventy percent of pests belong to lepidopteran species, so it would be interesting to explore the highly conserved genes involved in oogenesis that do not affect growth and development in the lepidopteran model, Bombyx mori. This can provide potential target genes for pest control and promote the development of insect sterility technology. RESULTS In lepidopteran species, ovarian serine protease (Osp), which encodes a member of the serine protease family, is essential for oogenesis. In this study, we used transgenic CRISPR/Cas9 technology to obtain Osp mutants in the model lepidopteran insect Bombyx mori and in the lepidopteran agricultural pest Spodoptera litura. Sequence analysis of mutants revealed an array of deletions in Osp loci in both species. We found that the deletion of Osp resulted in female sterility, whereas male fertility was not affected. Although B. mori and S. litura mutant females mated normally, they laid fewer eggs than wild-type females and eggs did not hatch. CONCLUSION Osp is crucial for female reproductive success in two species of Lepidoptera. As the Osp gene is highly conserved in insect species, this gene is a potential molecular target for genetic-based pest management. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Xia Xu
- School of Life Science, East China Normal University, Shanghai, China
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Honglun Bi
- School of Life Science, East China Normal University, Shanghai, China
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Yaohui Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Xiaowei Li
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Jun Xu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Zulian Liu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Lin He
- School of Life Science, East China Normal University, Shanghai, China
| | - Kai Li
- School of Life Science, East China Normal University, Shanghai, China
| | - Yongping Huang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
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Abstract
Terminal regions of the early Drosophila embryo are patterned by the highly conserved ERK cascade, giving rise to the nonsegmented terminal structures of the future larva. In less than an hour, this signaling event establishes several gene expression boundaries and sets in motion a sequence of elaborate morphogenetic events. Genetic studies of terminal patterning discovered signaling components and transcription factors that are involved in numerous developmental contexts and deregulated in human diseases. This review summarizes current understanding of signaling and morphogenesis during terminal patterning and discusses several open questions that can now be rigorously investigated using live imaging, omics, and optogenetic approaches. The anatomical simplicity of the terminal patterning system and its amenability to a broad range of increasingly sophisticated genetic perturbations will continue to make it a premier quantitative model for studying multiple aspects of tissue patterning by dynamically controlled cell signaling pathways.
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Taylor SE, Tuffery J, Bakopoulos D, Lequeux S, Warr CG, Johnson TK, Dearden PK. The torso-like gene functions to maintain the structure of the vitelline membrane in Nasonia vitripennis, implying its co-option into Drosophila axis formation. Biol Open 2019; 8:bio.046284. [PMID: 31488408 PMCID: PMC6777369 DOI: 10.1242/bio.046284] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Axis specification is a fundamental developmental process. Despite this, the mechanisms by which it is controlled across insect taxa are strikingly different. An excellent example of this is terminal patterning, which in Diptera such as Drosophila melanogaster occurs via the localized activation of the receptor tyrosine kinase Torso. In Hymenoptera, however, the same process appears to be achieved via localized mRNA. How these mechanisms evolved and what they evolved from remains largely unexplored. Here, we show that torso-like, known for its role in Drosophila terminal patterning, is instead required for the integrity of the vitelline membrane in the hymenopteran wasp Nasonia vitripennis. We find that other genes known to be involved in Drosophila terminal patterning, such as torso and Ptth, also do not function in Nasonia embryonic development. These findings extended to orthologues of Drosophila vitelline membrane proteins known to play a role in localizing Torso-like in Drosophila; in Nasonia these are instead required for dorso–ventral patterning, gastrulation and potentially terminal patterning. Our data underscore the importance of the vitelline membrane in insect development, and implies phenotypes caused by knockdown of torso-like must be interpreted in light of its function in the vitelline membrane. In addition, our data imply that the signalling components of the Drosophila terminal patterning systems were co-opted from roles in regulating moulting, and co-option into terminal patterning involved the evolution of a novel interaction with the vitelline membrane protein Torso-like. This article has an associated First Person interview with the first author of the paper. Summary: In the parasitic wasp Nasonia, Tsl, a key component of the process that defines the termini of the embryo of Drosophila, has a function in the structure of the vitelline membrane.
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Affiliation(s)
- Shannon E Taylor
- Genomics Aotearoa and Biochemistry Department, University of Otago, P.O. Box 56, Dunedin, Aotearoa-New Zealand
| | - Jack Tuffery
- Genomics Aotearoa and Biochemistry Department, University of Otago, P.O. Box 56, Dunedin, Aotearoa-New Zealand
| | - Daniel Bakopoulos
- School of Biological Sciences, Monash University, 18 Innovation Walk, Clayton VIC 3800, Australia
| | - Sharon Lequeux
- Otago Micro- and Nano- scale Imaging, University of Otago, PO Box 913, Dunedin, New Zealand, Aotearoa-New Zealand
| | - Coral G Warr
- School of Medicine, University of Tasmania, 17 Liverpool St Hobart, TAS 7000, Australia
| | - Travis K Johnson
- School of Biological Sciences, Monash University, 18 Innovation Walk, Clayton VIC 3800, Australia
| | - Peter K Dearden
- Genomics Aotearoa and Biochemistry Department, University of Otago, P.O. Box 56, Dunedin, Aotearoa-New Zealand
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Skelly J, Pushparajan C, Duncan EJ, Dearden PK. Evolution of the Torso activation cassette, a pathway required for terminal patterning and moulting. INSECT MOLECULAR BIOLOGY 2019; 28:392-408. [PMID: 30548465 DOI: 10.1111/imb.12560] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Embryonic terminal patterning and moulting are critical developmental processes in insects. In Drosophila and Tribolium both of these processes are regulated by the Torso-activation cassette (TAC). The TAC consists of a common receptor, Torso, ligands Trunk and prothoracicotropic hormone (PTTH), and the spatially restricted protein Torso-like, with combinations of these elements acting mechanistically to activate the receptor in different developmental contexts. In order to trace the evolutionary history of the TAC we determined the presence or absence of TAC components in the genomes of arthropods. Our analyses reveal that Torso, Trunk and PTTH are evolutionarily labile components of the TAC with multiple individual or combined losses occurring in the arthropod lineages leading to and within the insects. These losses are often correlated, with both ligands and receptor missing from the genome of the same species. We determine that the PTTH gene evolved in the common ancestor of Hemiptera and Holometabola, and is missing from the genomes of a number of species with experimentally demonstrated PTTH activity, implying another molecule may be involved in ecdysis in these species. In contrast, the torso-like gene is a common component of pancrustacean genomes.
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Affiliation(s)
- J Skelly
- Laboratory for Evolution and Development, Genomics Aotearoa, Biochemistry Department, University of Otago, Dunedin, Aotearoa-New Zealand
| | - C Pushparajan
- Laboratory for Evolution and Development, Genomics Aotearoa, Biochemistry Department, University of Otago, Dunedin, Aotearoa-New Zealand
| | - E J Duncan
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - P K Dearden
- Laboratory for Evolution and Development, Genomics Aotearoa, Biochemistry Department, University of Otago, Dunedin, Aotearoa-New Zealand
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Mineo A, Furriols M, Casanova J. The trigger (and the restriction) of Torso RTK activation. Open Biol 2018; 8:180180. [PMID: 30977718 PMCID: PMC6303783 DOI: 10.1098/rsob.180180] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 11/08/2018] [Indexed: 01/09/2023] Open
Abstract
The Torso pathway is an ideal model of receptor tyrosine kinase systems, in particular when addressing questions such as how receptor activity is turned on and, equally important, how it is restricted, how different outcomes can be generated from a single signal, and the extent to which gene regulation by signalling pathways relies on the relief of transcriptional repression. In this regard, we considered it pertinent to single out the fundamental notions learned from the Torso pathway beyond the specificities of this system (Furriols and Casanova 2003 EMBO J. 22, 1947-1952. ( doi:10.1093/emboj/cdg224 )). Since then, the Torso system has gained relevance and its implications beyond its original involvement in morphogenesis and into many disciplines such as oncogenesis, hormone control and neurobiology are now acknowledged. Thus, we believe that it is timely to highlight additional notions supported by new findings and to draw attention to future prospects. Given the late development of research in the field, we wish to devote this review to the events leading to the activation of the Torso receptor, the main focus of our most recent work.
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Affiliation(s)
- Alessandro Mineo
- Institut de Biologia Molecular de Barcelona (CSIC), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
- Institut de Recerca Biomèdica de Barcelona, (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
| | - Marc Furriols
- Institut de Biologia Molecular de Barcelona (CSIC), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
- Institut de Recerca Biomèdica de Barcelona, (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
| | - Jordi Casanova
- Institut de Biologia Molecular de Barcelona (CSIC), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
- Institut de Recerca Biomèdica de Barcelona, (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
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11
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Holes in the Plasma Membrane Mimic Torso-Like Perforin in Torso Tyrosine Kinase Receptor Activation in the Drosophila Embryo. Genetics 2018; 210:257-262. [PMID: 30049783 DOI: 10.1534/genetics.118.301397] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/24/2018] [Indexed: 11/18/2022] Open
Abstract
Receptor tyrosine kinase (RTK) pathways play central roles in development, and, when abnormally activated, they can lead to pathological conditions, including oncogenesis. Thus, RTK activation, mediated by ligand binding, is under tight control, a critical step being the conversion of an inactive precursor into the active form of the ligand. A variety of mechanisms have been shown to be involved in this conversion; however, little attention has been paid to how mechanical phenomena may impinge on this process. Here we address this issue by studying Torso, an RTK activated at both poles of the Drosophila embryo at the blastoderm stage. Torso activation is induced by a cleaved form of Trunk, a growth factor-like protein, but it also requires the accumulation of the Torso-like (Tsl) protein at both ends of the blastoderm. Tsl is the only known protein in Drosophila bearing a membrane attack complex/perforin (MACPF) domain-a motif present in proteins involved in pore formation at cell membranes. However, while different hypotheses have been put forward to account for the function of Tsl in Torso receptor activation, little is known about its molecular role and whether it indeed contributes to membrane pore formation. Here, we show that mechanically induced holes in the Drosophila embryo can substitute for Tsl function. These results suggest that Tsl is required for an exchange between the interior of the Drosophila embryo and its surrounding milieu and that mechanically induced cell injuries may contribute to abnormal RTK activation.
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