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Advances in Experimental Medicine and... 2018Pioneering cell aggregation experiments from the Artavanis-Tsakonas group in the late 1980's localized the core ligand recognition sequence in the Drosophila Notch... (Review)
Review
Pioneering cell aggregation experiments from the Artavanis-Tsakonas group in the late 1980's localized the core ligand recognition sequence in the Drosophila Notch receptor to epidermal growth factor-like (EGF) domains 11 and 12. Since then, advances in protein expression, structure determination methods and functional assays have enabled us to define the molecular basis of the core receptor/ligand interaction and given new insights into the architecture of the Notch complex at the cell surface. We now know that Notch EGF11 and 12 interact with the Delta/Serrate/LAG-2 (DSL) and C2 domains of ligand and that membrane-binding, together with additional protein-protein interactions outside the core recognition domains, are likely to fine-tune generation of the Notch signal. Furthermore, structure determination of O-glycosylated variants of Notch alone or in complex with receptor fragments, has shown that these sugars contribute directly to the binding interface, as well as to stabilizing intra-molecular domain structure, providing some mechanistic insights into the observed modulatory effects of O-glycosylation on Notch activity.Future challenges lie in determining the complete extracellular architecture of ligand and receptor in order to understand (i) how Notch/ligand complexes may form at the cell surface in response to physiological cues, (ii) the role of lipid binding in stabilizing the Notch/ligand complex, (iii) the impact of O-glycosylation on binding and signalling and (iv) to dissect the different pathologies that arise as a consequence of mutations that affect proteins involved in the Notch pathway.
Topics: Animals; Drosophila Proteins; Drosophila melanogaster; Glycosylation; Ligands; Protein Domains; Receptors, Notch; Signal Transduction
PubMed: 30030820
DOI: 10.1007/978-3-319-89512-3_2 -
Briefings in Functional Genomics Sep 2012Drosophila melanogaster is an established model organism for the study of host-pathogen interactions. The sequencing of its genome allowed the prediction of all the... (Review)
Review
Drosophila melanogaster is an established model organism for the study of host-pathogen interactions. The sequencing of its genome allowed the prediction of all the genes encoded in it and, consequently, enabled a more comprehensive view of its immune responses. Whole-genome transcription analyses of Drosophila response to bacteria, fungi, parasitoids and viruses allow a comparison of the response between different classes of microorganisms and between pathogens of the same class. Overall, there is great diversity in the immune responses but there are a few pathways that are frequently activated. These studies provide a better understanding of how the host resists the infection and responds to the associated damage. Moreover, the data give insights into how microorganisms can manipulate their host and successfully establish an infection.
Topics: Animals; Drosophila Proteins; Drosophila melanogaster; Genome, Insect; Host-Pathogen Interactions
PubMed: 23023664
DOI: 10.1093/bfgp/els043 -
Methods in Enzymology 2010As glycan characterization methods increase in sensitivity, new opportunities arise to undertake glycomic analyses on limiting amounts of material. Developing systems... (Review)
Review
As glycan characterization methods increase in sensitivity, new opportunities arise to undertake glycomic analyses on limiting amounts of material. Developing systems present special challenges since the amount of available tissue can restrict deep glycan characterization. We have optimized mass spectrometric methods with the goal of obtaining full glycan profiles from small amounts of tissue derived from organisms of particular interest. A major target of our efforts has been the Drosophila embryo, allowing us to leverage the tools already developed in this organism to meld glycomics, genomics, and molecular genetics. Our analysis of the N-linked, O-linked (non-GAG), and glycosphingolipid (GSL) glycans of the Drosophila embryo have identified expected and unexpected glycan structures. We have verified previous findings regarding the predominance of high-Man and pauci-Man N-linked glycans, but have also detected minor families of sialylated and glucuronylated N-linked structures. Glucuronic acid (GlcA) also presents itself as an abundant modification of O-linked and GSL glycans. We describe critical advancements in our methodology and present the broad range of contexts in which GlcA is found in the Drosophila embryo.
Topics: Algorithms; Animals; Carbohydrate Metabolism; Carbohydrate Sequence; Chemistry Techniques, Analytical; Drosophila Proteins; Drosophila melanogaster; Glycomics; Glycosylation; Humans; Lipids; Male; Molecular Sequence Data; Polysaccharides
PubMed: 20816215
DOI: 10.1016/S0076-6879(10)80014-X -
Developmental Cell Jun 2021Toll receptors are key determinants of planar polarity during Drosophila gastrulation. Two papers in the current issue of Developmental Cell now identify key features of...
Toll receptors are key determinants of planar polarity during Drosophila gastrulation. Two papers in the current issue of Developmental Cell now identify key features of their downstream signaling that allow cell symmetry to be broken by apparently non-polarized Toll receptors.
Topics: Animals; Drosophila; Drosophila Proteins; Gastrulation; Signal Transduction
PubMed: 34102101
DOI: 10.1016/j.devcel.2021.05.013 -
The European Journal of Neuroscience Jan 2020A central question in the circadian biology field concerns the mechanisms that translate ~24-hr oscillations of the molecular clock into overt rhythms. Drosophila... (Review)
Review
A central question in the circadian biology field concerns the mechanisms that translate ~24-hr oscillations of the molecular clock into overt rhythms. Drosophila melanogaster is a powerful system that provided the first understanding of how molecular clocks are generated and is now illuminating the neural basis of circadian behavior. The identity of ~150 clock neurons in the Drosophila brain and their roles in shaping circadian rhythms of locomotor activity have been described before. This review summarizes mechanisms that transmit time-of-day signals from the clock, within the clock network as well as downstream of it. We also discuss the identification of functional multisynaptic circuits between clock neurons and output neurons that regulate locomotor activity.
Topics: Animals; Brain; Circadian Clocks; Circadian Rhythm; Drosophila; Drosophila Proteins; Drosophila melanogaster
PubMed: 30059181
DOI: 10.1111/ejn.14092 -
ACS Chemical Neuroscience Mar 2023Visualizing neuronal anatomy often requires labor-intensive immunohistochemistry on fixed and dissected brains. To facilitate rapid anatomical staining in live brains,...
Visualizing neuronal anatomy often requires labor-intensive immunohistochemistry on fixed and dissected brains. To facilitate rapid anatomical staining in live brains, we used genetically targeted membrane tethers that covalently link fluorescent dyes for in vivo neuronal labeling. We generated a series of extracellularly trafficked small-molecule tethering proteins, HaloTag-CD4 (Kirk et al. , , 754027) and SNAP-CD4, which directly label transgene-expressing cells with commercially available ligand-substituted fluorescent dyes. We created stable transgenic reporter lines, which express extracellular HaloTag-CD4 and SNAP-CD4 with LexA and Gal4 drivers. Expressing these enzymes in live brains, we labeled the expression patterns of various Gal4 driver lines recapitulating histological staining in live-brain tissues. Pan-neural expression of SNAP-CD4 enabled the registration of live brains to an existing template for anatomical comparisons. We predict that these extracellular platforms will not only become a valuable complement to existing anatomical methods but will also prove useful for future genetic targeting of other small-molecule probes, drugs, and actuators.
Topics: Animals; Drosophila; Neuroanatomy; Fluorescent Dyes; Animals, Genetically Modified; Drosophila Proteins
PubMed: 36799505
DOI: 10.1021/acschemneuro.2c00745 -
Current Topics in Developmental Biology 2022The molecular complexes underlying planar cell polarity (PCP) were first identified in Drosophila through analysis of mutant phenotypes in the adult cuticle and the... (Review)
Review
The molecular complexes underlying planar cell polarity (PCP) were first identified in Drosophila through analysis of mutant phenotypes in the adult cuticle and the orientation of associated polarized protrusions such as wing hairs and sensory bristles. The same molecules are conserved in vertebrates and are required for the localization of polarized protrusions such as primary or sensory cilia and the orientation of hair follicles. Not only is PCP signaling required to align cellular structures across a tissue, it is also required to coordinate movement during embryonic development and adult homeostasis. PCP signaling allows cells to interpret positional cues within a tissue to move in the appropriate direction and to coordinate this movement with their neighbors. In this review we outline the molecular basis of the core Wnt-Frizzled/PCP pathway, and describe how this signaling orchestrates collective motility in Drosophila and vertebrates. Here we cover the paradigms of ommatidial rotation and border cell migration in Drosophila, and convergent extension in vertebrates. The downstream cell biological processes that underlie polarized motility include cytoskeletal reorganization, and adherens junctional and extracellular matrix remodeling. We discuss the contributions of these processes in the respective cell motility contexts. Finally, we address examples of individual cell motility guided by PCP factors during nervous system development and in cancer disease contexts.
Topics: Animals; Cell Movement; Cell Polarity; Drosophila; Drosophila Proteins; Vertebrates; Wnt Signaling Pathway
PubMed: 35817505
DOI: 10.1016/bs.ctdb.2022.03.006 -
Genetics Oct 2021Embryonic patterning is critically dependent on zygotic genome activation (ZGA). In Drosophila melanogaster embryos, the pioneer factor Zelda directs ZGA, possibly in...
Embryonic patterning is critically dependent on zygotic genome activation (ZGA). In Drosophila melanogaster embryos, the pioneer factor Zelda directs ZGA, possibly in conjunction with other factors. Here, we have explored the novel involvement of Chromatin-Linked Adapter for MSL Proteins (CLAMP) during ZGA. CLAMP binds thousands of sites genome-wide throughout early embryogenesis. Interestingly, CLAMP relocates to target promoter sequences across the genome when ZGA is initiated. Although there is a considerable overlap between CLAMP and Zelda binding sites, the proteins display distinct temporal dynamics. To assess whether CLAMP occupancy affects gene expression, we analyzed transcriptomes of embryos zygotically compromised for either clamp or zelda and found that transcript levels of many zygotically activated genes are similarly affected. Importantly, compromising either clamp or zelda disrupted the expression of critical segmentation and sex determination genes bound by CLAMP (and Zelda). Furthermore, clamp knockdown embryos recapitulate other phenotypes observed in Zelda-depleted embryos, including nuclear division defects, centrosome aberrations, and a disorganized actomyosin network. Based on these data, we propose that CLAMP acts in concert with Zelda to regulate early zygotic transcription.
Topics: Animals; Binding Sites; DNA-Binding Proteins; Drosophila Proteins; Drosophila melanogaster; Gene Expression Regulation, Developmental; Nuclear Proteins; Protein Binding; Zygote
PubMed: 34849887
DOI: 10.1093/genetics/iyab107 -
Cells Feb 2024Cell death plays an essential function in organismal development, wellbeing, and ageing. Many types of cell deaths have been described in the past 30 years. Among these,... (Review)
Review
Cell death plays an essential function in organismal development, wellbeing, and ageing. Many types of cell deaths have been described in the past 30 years. Among these, apoptosis remains the most conserved type of cell death in metazoans and the most common mechanism for deleting unwanted cells. Other types of cell deaths that often play roles in specific contexts or upon pathological insults can be classed under variant forms of cell death and programmed necrosis. Studies in have contributed significantly to the understanding and regulation of apoptosis pathways. In addition to this, has also served as an essential model to study the genetic basis of autophagy-dependent cell death (ADCD) and other relatively rare types of context-dependent cell deaths. Here, we summarise what is known about apoptosis, ADCD, and other context-specific variant cell death pathways in , with a focus on developmental cell death.
Topics: Animals; Drosophila; Cell Death; Apoptosis; Drosophila Proteins; Autophagic Cell Death
PubMed: 38391960
DOI: 10.3390/cells13040347 -
Genome Jun 2024The last decade has been highlighted by the increased use of next-generation DNA sequencing technology to identify novel human disease genes. A critical downstream part... (Review)
Review
The last decade has been highlighted by the increased use of next-generation DNA sequencing technology to identify novel human disease genes. A critical downstream part of this process is assigning function to a candidate gene variant. Functional studies in , the common fruit fly, have made a prominent contribution in annotating variant impact in an in vivo system. The use of patient-derived knock-in flies or rescue-based, "humanization", approaches are novel and valuable strategies in variant testing but have been recently widely reviewed. An often-overlooked strategy for determining variant impact has been GAL4/upstream activation sequence-mediated tissue-defined overexpression in . This mini-review will summarize the recent contribution of ectopic overexpression of human reference and variant cDNA in to assess variant function, interpret the consequence of the variant, and in some cases infer biological mechanisms.
Topics: Animals; Drosophila melanogaster; Humans; Genetic Variation; Drosophila Proteins
PubMed: 38412472
DOI: 10.1139/gen-2023-0135