Genetic Modifier Screens Reveal New Components that Interact with the Drosophila Dystroglycan-Dystrophin Complex

University of Arkansas, United States of America
PLoS ONE (Impact Factor: 3.53). 02/2008; 3(6):e2418. DOI: 10.1371/journal.pone.0002418
Source: PubMed

ABSTRACT The Dystroglycan-Dystrophin (Dg-Dys) complex has a capacity to transmit information from the extracellular matrix to the cytoskeleton inside the cell. It is proposed that this interaction is under tight regulation; however the signaling/regulatory components of Dg-Dys complex remain elusive. Understanding the regulation of the complex is critical since defects in this complex cause muscular dystrophy in humans. To reveal new regulators of the Dg-Dys complex, we used a model organism Drosophila melanogaster and performed genetic interaction screens to identify modifiers of Dg and Dys mutants in Drosophila wing veins. These mutant screens revealed that the Dg-Dys complex interacts with genes involved in muscle function and components of Notch, TGF-beta and EGFR signaling pathways. In addition, components of pathways that are required for cellular and/or axonal migration through cytoskeletal regulation, such as Semaphorin-Plexin, Frazzled-Netrin and Slit-Robo pathways show interactions with Dys and/or Dg. These data suggest that the Dg-Dys complex and the other pathways regulating extracellular information transfer to the cytoskeletal dynamics are more intercalated than previously thought.

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    • "Gieseler et al. 2000; Mariol & Ségalat 2001), flies (e.g. Kucherenko et al. 2008), and mice (Deconinck et al. 1997) have thus turned to study sensitized strains in an attempt to recapitulate the human phenotype. However, genetic sensitization may limit the applicability of results to MD that occurs in humans with mutations only in dystrophin (Monaco et al. 1986). "
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    ABSTRACT: The nematode Caenorhabditis elegans has been a powerful model system for the study of key muscle genes relevant to human neuromuscular function and disorders. The behavioral robustness of C. elegans, however, has hindered its use in the study of certain neuromuscular disorders because many worm models of human disease show only subtle phenotypes while crawling. By contrast, in their natural habitat, C. elegans likely spends much of the time burrowing through the soil matrix. We developed a burrowing assay to challenge motor output by placing worms in agar-filled pipettes of increasing densities. We find that burrowing involves distinct kinematics and turning strategies from crawling that vary with the properties of the substrate. We show that mutants mimicking Duchenne muscular dystrophy by lacking a functional ortholog of the dystrophin protein, DYS-1, crawl normally but are severely impaired in burrowing. Muscular degeneration in the dys-1 mutant is hastened and exacerbated by burrowing, while wild-type shows no such damage. To test whether neuromuscular integrity might be compensated genetically in the dys-1 mutant, we performed a genetic screen and isolated several suppressor mutants with proficient burrowing in a dys-1 mutant background. Further study of burrowing in C. elegans will enhance the study of diseases affecting neuromuscular integrity, and will provide insights into the natural behavior of this and other nematodes. This article is protected by copyright. All rights reserved.
    Genes Brain and Behavior 04/2015; 14(4). DOI:10.1111/gbb.12217 · 3.51 Impact Factor
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    • "Aphid populations grow exponentially, as observed in the dsGFP control treatment, but RNAi of MpC002 causes a 60% decline in the aphid population growth compared with 40% of Rack1 and MpPIntO2. This confirms previous assessments that C002 has an important function in aphids (Mutti et al., 2008; Bos et al., 2010), more so than a conserved multifunctional gene, such as Rack1, which has important functions in a number of organisms; knock-down of Rack1 results in developmentally defective phenotypes in C. elegans (Kamath et al., 2003; Simmer et al., 2003; Ciche and Sternberg, 2007) and Drosophila melanogaster (Kadrmas et al., 2007; Kucherenko et al., 2008). The impact of down-regulation of MpPIntO2 is similar to that of Rack1, indicating that MpPIntO2 also has important functions in GPA. "
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    ABSTRACT: Plant-mediated RNA interference (RNAi) has been successfully used as a tool to study gene function in aphids. The persistence and transgenerational effects of plant-mediated RNAi in the green peach aphid (GPA) Myzus persicae were investigated, with a focus on three genes with different functions in the aphid. Rack1 is a key component of various cellular processes inside aphids, while candidate effector genes MpC002 and MpPIntO2 (Mp2) modulate aphid-plant interactions. The gene sequences and functions did not affect RNAi-mediated down-regulation and persistence levels in the aphids. Maximal reduction of gene expression was ~70% and this was achieved at between 4 d and 8 d of exposure of the aphids to double-stranded RNA (dsRNA)-producing transgenic Arabidopsis thaliana. Moreover, gene expression levels returned to wild-type levels within ~6 d after removal of the aphids from the transgenic plants, indicating that a continuous supply of dsRNA is required to maintain the RNAi effect. Target genes were also down-regulated in nymphs born from mothers exposed to dsRNA-producing transgenic plants, and the RNAi effect lasted twice as long (12-14 d) in these nymphs. Investigations of the impact of RNAi over three generations of aphids revealed that aphids reared on dsMpC002 transgenic plants experienced a 60% decline in aphid reproduction levels compared with a 40% decline of aphids reared on dsRack1 and dsMpPIntO2 plants. In a field setting, a reduction of the aphid reproduction by 40-60% would dramatically decrease aphid population growth, contributing to a substantial reduction in agricultural losses. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.
    Journal of Experimental Botany 11/2014; 66(2). DOI:10.1093/jxb/eru450 · 5.79 Impact Factor
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    • "However, if the genes act in the same pathway, then mutations in two steps should enhance each other and cause a phenotype. To identify dominant suppressors/ enhancers of the muscle degeneration phenotype, virgin females Dys N-RNAi :act-Gal4 and Dg RNAi :tub-Gal4 (Kucherenko et al., 2008) that have 2.5 and 6 fold mRNA downregulation, respectively (Supplementary Tables 1, 2) were crossed to males carrying the screened mutation. Alleles used for the screen were obtained from DGRC and BDSC. "
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    ABSTRACT: In Drosophila, like in humans, Dystrophin Glycoprotein Complex (DGC) deficiencies cause a life span shortening disease, associated with muscle dysfunction. We performed the first in vivo genetic interaction screen in ageing dystrophic muscles and identified genes that have not been shown before to have a role in the development of muscular dystrophy and interact with dystrophin and/or dystroglycan. Mutations in many of the found interacting genes cause age-dependent morphological and heat-induced physiological defects in muscles, suggesting their importance in the tissue. Majority of them is phylogenetically conserved and implicated in human disorders, mainly tumors and myopathies. Functionally they can be divided into three main categories: proteins involved in communication between muscle and neuron, and interestingly, in mechanical and cellular stress response pathways. Our data show that stress induces muscle degeneration and accelerates age-dependent muscular dystrophy. Dystrophic muscles are already compromised; and as a consequence they are less adaptive and more sensitive to energetic stress and to changes in the ambient temperature. However, only dystroglycan, but not dystrophin deficiency causes extreme myodegeneration induced by energetic stress suggesting that dystroglycan might be a component of the low-energy pathway and act as a transducer of energetic stress in normal and dystrophic muscles.
    Developmental Biology 04/2011; 352(2):228-42. DOI:10.1016/j.ydbio.2011.01.013 · 3.64 Impact Factor
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