scholarly journals Actin bundles play a different role in shaping scales compared to bristles in the mosquito Aedes aegypti

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sanja Djokic ◽  
Anna Bakhrat ◽  
Ido Tsurim ◽  
Nadya Urakova ◽  
Jason L. Rasgon ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Actin Polymerization ◽  
Developmental Process ◽  
Morphological Changes ◽  
Actin Bundle ◽  
Actin Bundles ◽  
Flat Shape ◽  
Cellular Extensions ◽  
And Function

Abstract Insect epithelial cells contain cellular extensions such as bristles, hairs, and scales. These cellular extensions are homologous structures that differ in morphology and function. They contain actin bundles that dictate their cellular morphology. While the organization, function, and identity of the major actin-bundling proteins in bristles and hairs are known, this information on scales is unknown. In this study, we characterized the development of scales and the role of actin bundles in the mosquito, Aedes aegypti. We show that scales undergo drastic morphological changes during development, from a cylindrical to flat shape with longer membrane invagination. Scale actin-bundle distribution changes from the symmetrical organization of actin bundles located throughout the bristle membrane to an asymmetrical organization. By chemically inhibiting actin polymerization and by knocking out the forked gene in the mosquito (Ae-Forked; a known actin-bundling protein) by CRISPR-Cas9 gene editing, we showed that actin bundles are required for shaping bristle, hair, and scale morphology. We demonstrated that actin bundles and Ae-Forked are required for bristle elongation, but not for that of scales. In scales, actin bundles are required for width formation. In summary, our results reveal, for the first time, the developmental process of mosquito scale formation and also the role of actin bundles and actin-bundle proteins in scale morphogenesis. Moreover, our results reveal that although scale and bristle are thought to be homologous structures, actin bundles have a differential requirement in shaping mosquito scales compared to bristles.

scholarly journals Actin bundles play different role in shaping scale as compare to bristle in mosquito Aedes aegypti

2020 ◽  
Author(s):  
Sanja Djokic ◽  
Bakhrat Anna ◽  
Ido Zurim ◽  
Nadya Urakova ◽  
Jason L. Rasgon ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Actin Polymerization ◽  
Morphological Changes ◽  
Cylindrical Shape ◽  
Actin Bundles ◽  
Membrane Invagination ◽  
Flat Shape ◽  
Cellular Extensions ◽  
And Function

AbstractInsect epithelial cells contain cellular extensions such as bristles, hairs and scales. It has been suggested that these cellular extensions are homologous structures that differ in morphology and function. These cellular extensions contain actin bundles that dictate their cellular morphology; bristle and hair are cylindrical in shape, while scales are wider and flattened. While the organization, function and identity of the major actin bundling protein in bristles and hairs is known, this information in scales is unknown. In this study, we characterized the development of scales and the role of actin bundles in the mosquito, Aedes aegypti. We show that scales undergo drastic morphological changes during development, from cylindrical shape to flat shape with longer membrane invagination. Scale actin bundle distribution changes during development, from symmetrical organization of actin bundles located throughout the bristle membrane, to asymmetrical organization of the actin bundles. By chemically inhibiting actin polymerization and by knocking-out the forked gene in the mosquito (Ae-Forked; a known actin bundling protein), by CRISPR-Cas9 gene editing, we showed that actin bundles are required for shaping bristle, hair and scale morphology. We demonstrated that actin bundles and Ae-Forked are required for bristle elongation, but not that of scales. In scales, actin bundles are required for width formation. Our results reveal a differential requirement of actin bundles in shaping mosquito scales compared to bristles.

scholarly journals The N-Terminus ofDictyosteliumScar Interacts with Abi and HSPC300 and Is Essential for Proper Regulation and Function

2007 ◽  
Vol 18 (5) ◽  
pp. 1609-1620 ◽  
Author(s):  
Diana Caracino ◽  
Cheryl Jones ◽  
Mark Compton ◽  
Charles L. Saxe
Keyword(s):  
Actin Polymerization ◽  
Terminal Region ◽  
Wild Type ◽  
Large Molecular Weight ◽  
Weight Protein ◽  
And Function ◽  
Necessary And Sufficient

Scar/WAVE proteins, members of the conserved Wiskott-Aldrich syndrome (WAS) family, promote actin polymerization by activating the Arp2/3 complex. A number of proteins, including a complex containing Nap1, PIR121, Abi1/2, and HSPC300, interact with Scar/WAVE, though the role of this complex in regulating Scar function remains unclear. Here we identify a short N-terminal region of Dictyostelium Scar that is necessary and sufficient for interaction with HSPC300 and Abi in vitro. Cells expressing Scar lacking this N-terminal region show abnormalities in F-actin distribution, cell morphology, movement, and cytokinesis. This is true even in the presence of wild-type Scar. The data suggest that the first 96 amino acids of Scar are necessary for participation in a large-molecular-weight protein complex, and that this Scar-containing complex is responsible for the proper localization and regulation of Scar. The presence of mis-regulated or unregulated Scar has significant deleterious effects on cells and may explain the need to keep Scar activity tightly controlled in vivo either by assembly in a complex or by rapid degradation.

scholarly journals Disc and Actin-Associated Protein 1 Influence Host Attachment in the Intestinal Parasite Giardia lamblia

2021 ◽  
Author(s):  
Melissa C. Steele-Ogus ◽  
Ava M. Obenaus ◽  
Nathan J. Sniadecki ◽  
Alexander R. Paredez
Keyword(s):  
Conformational Changes ◽  
Giardia Lamblia ◽  
Actin Polymerization ◽  
Intestinal Parasite ◽  
Interacting Proteins ◽  
Associated Proteins ◽  
Promising Area ◽  
Ventral Disc ◽  
And Function

The deep-branching eukaryote Giardia lamblia is an extracellular parasite that attaches to the host intestine via a microtubule-based structure called the ventral disc. Control of attachment is mediated in part by the movement of two regions of the ventral disc that either permit or exclude the passage of fluid under the disc. Several known disc-associated proteins (DAPs) contribute to disc structure and function, but no force-generating protein has been identified among them. We recently identified several Giardia actin (GlActin) interacting proteins at the ventral disc, which could potentially employ actin polymerization for force generation and disc conformational changes. One of these proteins, Disc and Actin Associated Protein 1 (DAAP1), is highly enriched at the two regions of the disc previously shown to be important for fluid flow during attachment. In this study, we investigate the role of both GlActin and DAAP1 in ventral disc morphology and function. We confirmed interaction between GlActin and DAAP1 through coimmunoprecipitation, and used immunofluorescence to localize both proteins throughout the cell cycle and during trophozoite attachment. Similar to other DAPs, the association of DAAP1 with the disc is stable, except during cell division when the disc disassembles. Depletion of GlActin by translation-blocking antisense morpholinos resulted in both impaired attachment and defects in the ventral disc, indicating that GlActin contributes to disc-mediated attachment. Depletion of DAAP1 through CRISPR interference resulted in intact discs but impaired attachment, gating, and flow under the disc. As attachment is essential for infection, elucidation of these and other molecular mediators is a promising area for development of new therapeutics against a ubiquitous parasite.

scholarly journals Sophisticated Gene Regulation for a Complex Physiological System: The Role of Non-coding RNAs in Photoreceptor Cells

2021 ◽  
Vol 8 ◽  
Author(s):  
Sabrina Carrella ◽  
Sandro Banfi ◽  
Marianthi Karali
Keyword(s):  
Molecular Mechanisms ◽  
Developmental Process ◽  
Photoreceptor Cells ◽  
Sensory Transduction ◽  
Circular Rnas ◽  
Therapeutic Implications ◽  
Physiological Processes ◽  
Non Coding Rnas ◽  
And Function

Photoreceptors (PRs) are specialized neuroepithelial cells of the retina responsible for sensory transduction of light stimuli. In the highly structured vertebrate retina, PRs have a highly polarized modular structure to accommodate the demanding processes of phototransduction and the visual cycle. Because of their function, PRs are exposed to continuous cellular stress. PRs are therefore under pressure to maintain their function in defiance of constant environmental perturbation, besides being part of a highly sophisticated developmental process. All this translates into the need for tightly regulated and responsive molecular mechanisms that can reinforce transcriptional programs. It is commonly accepted that regulatory non-coding RNAs (ncRNAs), and in particular microRNAs (miRNAs), are not only involved but indeed central in conferring robustness and accuracy to developmental and physiological processes. Here we integrate recent findings on the role of regulatory ncRNAs (e.g., miRNAs, lncRNAs, circular RNAs, and antisense RNAs), and of their contribution to PR pathophysiology. We also outline the therapeutic implications of translational studies that harness ncRNAs to prevent PR degeneration and promote their survival and function.

scholarly journals An Atomic Model of Actin Filaments Cross-Linked by Fimbrin and Its Implications for Bundle Assembly and Function

2001 ◽  
Vol 153 (5) ◽  
pp. 947-956 ◽  
Author(s):  
Niels Volkmann ◽  
David DeRosier ◽  
Paul Matsudaira ◽  
Dorit Hanein
Keyword(s):  
Conformational Changes ◽  
Structural Characterization ◽  
Actin Polymerization ◽  
Two Dimensions ◽  
Atomic Model ◽  
Cross Linking ◽  
Cross Link ◽  
Actin Bundles ◽  
The Cross ◽  
And Function

Actin bundles have profound effects on cellular shape, division, adhesion, motility, and signaling. Fimbrin belongs to a large family of actin-bundling proteins and is involved in the formation of tightly ordered cross-linked bundles in the brush border microvilli and in the stereocilia of inner ear hair cells. Polymorphism in these three-dimensional (3D) bundles has prevented the detailed structural characterization required for in-depth understanding of their morphogenesis and function. Here, we describe the structural characterization of two-dimensional arrays of actin cross-linked with human T-fimbrin. Structural information obtained by electron microscopy, x-ray crystallography, and homology modeling allowed us to build the first molecular model for the complete actin–fimbrin cross-link. The restriction of the arrays to two dimensions allowed us to deduce the spatial relationship between the components, the mode of fimbrin cross-linking, and the flexibility within the cross-link. The atomic model of the fimbrin cross-link, the cross-linking rules deduced from the arrays, and the hexagonal packing of actin bundles in situ were all combined to generate an atomic model for 3D actin–fimbrin bundles. Furthermore, the assembly of the actin–fimbrin arrays suggests coupling between actin polymerization, fimbrin binding, and crossbridge formation, presumably achieved by a feedback between conformational changes and changes in affinity.

scholarly journals The diversity, structure and function of heritable adaptive immunity sequences in the Aedes aegypti genome

2017 ◽  
Author(s):  
Zachary J. Whitfield ◽  
Patrick T. Dolan ◽  
Mark Kunitomi ◽  
Michel Tassetto ◽  
Matthew G. Seetin ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Single Molecule ◽  
Large Scale ◽  
Insect Immunity ◽  
Genomic Context ◽  
Long Read ◽  
Aegypti Genome ◽  
Endogenous Viral Elements ◽  
And Function

AbstractThe Aedes aegypti mosquito is a major vector for arboviruses including dengue, chikungunya and Zika virus. Combating the spread of these viruses requires a more complete understanding of the mosquito immune system. Recent studies have implicated genomic endogenous viral elements (EVEs) derived from non-retroviral RNA viruses in insect immunity. Because these elements are inserted into repetitive regions of the mosquito genome, their large-scale structure and organization with respect to other genomic elements has been difficult to resolve with short-read sequencing. To better define the origin, diversity and biological role of EVEs, we employed single-molecule, real-time sequencing technology to generate a high quality, long-read assembly of the Ae. aegypti-derived Aag2 cell line genome. We leverage the quality and contiguity of this assembly to characterize the diversity and genomic context of EVEs in the genome of this important model system. We find that EVEs in the Aag2 genome are acquired through recombination by LTR retrotransposons, and organize into larger loci (>50kbp) characterized by high LTR density. These EVE containing loci are associated with increased transcription factor binding sight density and increased production of anti-genomic piRNAs. We also detected piRNA processing corresponding to on-going viral infection. This global view of EVEs and piRNA responses demonstrates the ubiquity and diversity of these heritable elements that define small-RNA mediated antiviral immunity in mosquitoes.

scholarly journals Schizosaccharomyces pombe Sst4p, a Conserved Vps27/Hrs Homolog, Functions Downstream of Phosphatidylinositol 3-Kinase Pik3p To Mediate Proper Spore Formation

2007 ◽  
Vol 6 (12) ◽  
pp. 2343-2353 ◽  
Author(s):  
Masayuki Onishi ◽  
Michihiro Iida ◽  
Takako Koga ◽  
Sadayuki Yamada ◽  
Aiko Hirata ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fluorescent Protein ◽  
Developmental Process ◽  
Intracellular Membrane ◽  
Phosphatidylinositol 3 Kinase ◽  
Fyve Domain ◽  
Membrane Compartments ◽  
And Function ◽  
Phosphatidylinositol 3

ABSTRACT Sporulation of the fission yeast Schizosaccharomyces pombe is a developmental process that generates gametes and that includes the formation of spore envelope precursors called the forespore membranes. Assembly and development of forespore membranes require vesicular trafficking from other intracellular membrane compartments. We have shown that phosphatidylinositol 3-kinase (PtdIns 3-kinase) is required for efficient and proper development of forespore membranes. The role of a FYVE domain protein, Sst4p, a homolog of Vps27p/Hrs, as a downstream factor for PtdIns 3-kinase in sporulation was investigated. sst4Δ asci formed spores with oval-shaped morphology and with reduced viability compared to that of the wild-type spores. The extension of forespore membranes was inefficient, and bubble-like structures emerged from the leading edges of the forespore membranes. Sst4p localization was examined using fluorescent protein fusions and was found to be adjacent to the forespore membranes during sporulation. The localization and function of Sst4p were dependent on its FYVE domain and on PtdIns 3-kinase. Sst4p colocalized and interacted with Hse1p, a homolog of Saccharomyces cerevisiae Hse1p and of mammalian STAM. Mutations in all three UIM domains of the Sst4p/Hse1p complex resulted in formation of spores with abnormal morphology. These results suggest that Sst4p is a downstream factor of PtdIns 3-kinase and functions in forespore membrane formation.

scholarly journals Cofilin-mediated actin dynamics promotes actin bundle formation during Drosophila bristle development

2016 ◽  
Vol 27 (16) ◽  
pp. 2554-2564 ◽  
Author(s):  
Jing Wu ◽  
Heng Wang ◽  
Xuan Guo ◽  
Jiong Chen
Keyword(s):  
Actin Filament ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Model System ◽  
Actin Dynamics ◽  
Actin Network ◽  
Loss Of Function ◽  
Actin Bundle ◽  
Actin Bundles

The actin bundle is an array of linear actin filaments cross-linked by actin-bundling proteins, but its assembly and dynamics are not as well understood as those of the branched actin network. Here we used the Drosophila bristle as a model system to study actin bundle formation. We found that cofilin, a major actin disassembly factor of the branched actin network, promotes the formation and positioning of actin bundles in the developing bristles. Loss of function of cofilin or AIP1, a cofactor of cofilin, each resulted in increased F-actin levels and severe defects in actin bundle organization, with the defects from cofilin deficiency being more severe. Further analyses revealed that cofilin likely regulates actin bundle formation and positioning by the following means. First, cofilin promotes a large G-actin pool both locally and globally, likely ensuring rapid actin polymerization for bundle initiation and growth. Second, cofilin limits the size of a nonbundled actin-myosin network to regulate the positioning of actin bundles. Third, cofilin prevents incorrect assembly of branched and myosin-associated actin filament into bundles. Together these results demonstrate that the interaction between the dynamic dendritic actin network and the assembling actin bundles is critical for actin bundle formation and needs to be closely regulated.

Scanning electron microscopic study of collagen fibrillogenesis and extracellular compartmentalization in the chick embryo tendon

1986 ◽  
Vol 44 ◽  
pp. 208-209
Author(s):  
Grace C.H. Yang
Keyword(s):  
Chick Embryo ◽  
Extracellular Space ◽  
Fibroblast Cell ◽  
Collagen Fibrils ◽  
Electron Microscopic ◽  
Voltage Electron ◽  
Scanning Electron Microscopic Study ◽  
Microscopic Studies ◽  
And Function

The size and organization of collagen fibrils in the extracellular matrix is an important determinant of tissue structure and function. The synthesis and deposition of collagen involves multiple steps which begin within the cell and continue in the extracellular space. High-voltage electron microscopic studies of the chick embryo cornea and tendon suggested that the extracellular space is compartmentalized by the fibroblasts for the regulation of collagen fibril, bundle, and tissue specific macroaggregate formation. The purpose of this study is to gather direct evidence regarding the association of the fibroblast cell surface with newly formed collagen fibrils, and to define the role of the fibroblast in the control and the precise positioning of collagen fibrils, bundles, and macroaggregates during chick tendon development.

High resolution spot scan imaging of frozen, hydrated actin bundles with 400kV electrons

1992 ◽  
Vol 50 (1) ◽  
pp. 512-513
Author(s):  
J. Jakana ◽  
M.F. Schmid ◽  
P. Matsudaira ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Binding Proteins ◽  
Actin Binding ◽  
Eukaryotic Cells ◽  
Dimensional Structure ◽  
Structural Basis ◽  
Actin Bundle ◽  
Actin Bundles ◽  
3 Dimensional ◽  
Macromolecular Assembly

Actin is a protein found in all eukaryotic cells. In its polymerized form, the cells use it for motility, cytokinesis and for cytoskeletal support. An example of this latter class is the actin bundle in the acrosomal process from the Limulus sperm. The different functions actin performs seem to arise from its interaction with the actin binding proteins. A 3-dimensional structure of this macromolecular assembly is essential to provide a structural basis for understanding this interaction in relationship to its development and functions.

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