scholarly journals Turgor-dependent and coronin-mediated F-actin dynamics drive septin disc-to-ring remodeling in the blast fungus

2021 ◽  
pp. jcs.251298
Author(s):  
Nawaraj Dulal ◽  
Audra Mae Rogers ◽  
Rinalda Proko ◽  
Baronger Dowell Bieger ◽  
Rohana Liyanage ◽  
...  
Keyword(s):  
Magnaporthe Oryzae ◽  
Structural Integrity ◽  
Functional Organization ◽  
Actin Dynamics ◽  
Dependent Manner ◽  
Septin Ring ◽  
Fungal Plant Pathogen ◽  
Rice Leaves ◽  
Actin Rings ◽  
Insight Into

The fungus Magnaporthe oryzae uses a specialized pressure-generating infection cell called an appressorium to break into rice leaves and initiate disease. Appressorium functionality is dependent on the formation of a cortical septin ring during its morphogenesis, but precisely how this structure assembles is unclear. Here we show that F-actin rings are recruited to the circumference of incipient septin disc-like structures in a pressure-dependent manner, and that this is necessary for their contraction and remodeling into rings. We demonstrate that the structural integrity of these incipient septin discs requires both an intact F-actin and microtubule cytoskeleton and provide fundamental new insight into their functional organization within the appressorium. Lastly, using proximity-dependent, labelling we identify the actin modulator coronin as a septin proximal protein and show that F-actin-mediated septin disc-to-ring remodeling is perturbed in the genetic absence of coronin. Taken together, our findings provide new insight into the dynamic remodeling of infection-specific higher-order septin structures in a globally significant fungal plant pathogen.

scholarly journals Nicotine Induces Polyspermy in Sea Urchin Eggs through a Non-Cholinergic Pathway Modulating Actin Dynamics

Cells ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 63 ◽  
Author(s):  
Nunzia Limatola ◽  
Filip Vasilev ◽  
Luigia Santella ◽  
Jong Tai Chun
Keyword(s):  
Sea Urchin ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Molecular Mechanisms ◽  
Actin Dynamics ◽  
Dependent Manner ◽  
Animal Cells ◽  
Sea Urchin Eggs ◽  
Cholinergic Pathway ◽  
Dose Dependent

While alkaloids often exert unique pharmacological effects on animal cells, exposure of sea urchin eggs to nicotine causes polyspermy at fertilization in a dose-dependent manner. Here, we studied molecular mechanisms underlying the phenomenon. Although nicotine is an agonist of ionotropic acetylcholine receptors, we found that nicotine-induced polyspermy was neither mimicked by acetylcholine and carbachol nor inhibited by specific antagonists of nicotinic acetylcholine receptors. Unlike acetylcholine and carbachol, nicotine uniquely induced drastic rearrangement of egg cortical microfilaments in a dose-dependent way. Such cytoskeletal changes appeared to render the eggs more receptive to sperm, as judged by the significant alleviation of polyspermy by latrunculin-A and mycalolide-B. In addition, our fluorimetric assay provided the first evidence that nicotine directly accelerates polymerization kinetics of G-actin and attenuates depolymerization of preassembled F-actin. Furthermore, nicotine inhibited cofilin-induced disassembly of F-actin. Unexpectedly, our results suggest that effects of nicotine can also be mediated in some non-cholinergic pathways.

scholarly journals Control of microtubule dynamics using an optogenetic microtubule plus end–F-actin cross-linker

2017 ◽  
Vol 217 (2) ◽  
pp. 779-793 ◽  
Author(s):  
Rebecca C. Adikes ◽  
Ryan A. Hallett ◽  
Brian F. Saway ◽  
Brian Kuhlman ◽  
Kevin C. Slep
Keyword(s):  
Blue Light ◽  
Actin Binding ◽  
Cross Linking ◽  
Dependent Manner ◽  
Exclusion Zone ◽  
Actin Networks ◽  
Drosophila Melanogaster S2 Cells ◽  
Actin Binding Domain ◽  
Specific Factors ◽  
Insight Into

We developed a novel optogenetic tool, SxIP–improved light-inducible dimer (iLID), to facilitate the reversible recruitment of factors to microtubule (MT) plus ends in an end-binding protein–dependent manner using blue light. We show that SxIP-iLID can track MT plus ends and recruit tgRFP-SspB upon blue light activation. We used this system to investigate the effects of cross-linking MT plus ends and F-actin in Drosophila melanogaster S2 cells to gain insight into spectraplakin function and mechanism. We show that SxIP-iLID can be used to temporally recruit an F-actin binding domain to MT plus ends and cross-link the MT and F-actin networks. Cross-linking decreases MT growth velocities and generates a peripheral MT exclusion zone. SxIP-iLID facilitates the general recruitment of specific factors to MT plus ends with temporal control enabling researchers to systematically regulate MT plus end dynamics and probe MT plus end function in many biological processes.

Facing extremes: archaeal surface-layer (glyco)proteins

Microbiology ◽  
2003 ◽  
Vol 149 (12) ◽  
pp. 3347-3351 ◽  
Author(s):  
Jerry Eichler
Keyword(s):  
Surface Layer ◽  
Structural Integrity ◽  
Elevated Temperatures ◽  
Protein Biosynthesis ◽  
Extreme Environments ◽  
Archaeal Protein ◽  
The Face ◽  
Micro Organisms ◽  
Physical Challenges ◽  
Insight Into

Archaea are best known in their capacities as extremophiles, i.e. micro-organisms able to thrive in some of the most drastic environments on Earth. The protein-based surface layer that envelopes many archaeal strains must thus correctly assemble and maintain its structural integrity in the face of the physical challenges associated with, for instance, life in high salinity, at elevated temperatures or in acidic surroundings. Study of archaeal surface-layer (glyco)proteins has thus offered insight into the strategies employed by these proteins to survive direct contact with extreme environments, yet has also served to elucidate other aspects of archaeal protein biosynthesis, including glycosylation, lipid modification and protein export. In this mini-review, recent advances in the study of archaeal surface-layer (glyco)proteins are discussed.

Design and topological optimization of rear pressure bulkhead for a typical aircraft

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Marshal Thakran ◽  
Meenakshi ◽  
Jitender Sharma ◽  
Charles Gilbert Martin
Keyword(s):  
Numerical Analysis ◽  
Significant Influence ◽  
Design Methodology ◽  
Structural Integrity ◽  
Topological Optimization ◽  
Content Type ◽  
Iterative Design ◽  
Practical Implications ◽  
Insight Into ◽  
Selection Of

Purpose The purpose of this paper is to evaluate the model of a rear pressure bulkhead with different design optimizations to meet the pressurized cabin requirements of an aircraft. Design/methodology/approach This paper presents the results of the static analysis of a dome-shaped rear pressure bulkhead model designed in Catia-v5. Numerical analysis of model meshed in hyper-mesh and solved using Opti-Struct for iterative design optimizations. Findings All the iterative models are analyzed at 9 Psi. Rear pressure bulkhead designed with L-section stringer shows better results than the model optimized with T-section stringer for the same thickness. The model optimized with L-shaped stinger also reduces the weight of the bulkhead without affecting the structural integrity. Practical implications It has been concluded in this paper that the selection of specific shapes of the stringers shows a significant influence on weight reduction. Originality/value This paper provides a topical, technical insight into the design and development of a rear pressure bulkhead. It also outlines the future development of dome-shaped rear pressure bulkhead.

scholarly journals Functional Organization of the Yeast SAGA Complex: Distinct Components Involved in Structural Integrity, Nucleosome Acetylation, and TATA-Binding Protein Interaction

1999 ◽  
Vol 19 (1) ◽  
pp. 86-98 ◽  
Author(s):  
David E. Sterner ◽  
Patrick A. Grant ◽  
Shannon M. Roberts ◽  
Laura J. Duggan ◽  
Rimma Belotserkovskaya ◽  
...  
Keyword(s):  
Histone Acetylation ◽  
Structural Integrity ◽  
Functional Organization ◽  
Binding Protein ◽  
Tata Binding Protein ◽  
Saga Complex ◽  
Specific Domain ◽  
Nucleosomal Histone

ABSTRACT SAGA, a recently described protein complex in Saccharomyces cerevisiae, is important for transcription in vivo and possesses histone acetylation function. Here we report both biochemical and genetic analyses of members of three classes of transcription regulatory factors contained within the SAGA complex. We demonstrate a correlation between the phenotypic severity of SAGA mutants and SAGA structural integrity. Specifically, null mutations in the Gcn5/Ada2/Ada3 or Spt3/Spt8 classes cause moderate phenotypes and subtle structural alterations, while mutations in a third subgroup, Spt7/Spt20, as well as Ada1, disrupt the complex and cause severe phenotypes. Interestingly, double mutants (gcn5Δ spt3Δand gcn5Δ spt8Δ) causing loss of a member of each of the moderate classes have severe phenotypes, similar tospt7Δ, spt20Δ, or ada1Δmutants. In addition, we have investigated biochemical functions suggested by the moderate phenotypic classes and find that first, normal nucleosomal acetylation by SAGA requires a specific domain of Gcn5, termed the bromodomain. Deletion of this domain also causes specific transcriptional defects at the HIS3 promoter in vivo. Second, SAGA interacts with TBP, the TATA-binding protein, and this interaction requires Spt8 in vitro. Overall, our data demonstrate that SAGA harbors multiple, distinct transcription-related functions, including direct TBP interaction and nucleosomal histone acetylation. Loss of either of these causes slight impairment in vivo, but loss of both is highly detrimental to growth and transcription.

scholarly journals Resistance-related physiological response of rice leaves to the compound stress of enhanced UV-B radiation and Magnaporthe oryzae

2018 ◽  
Vol 13 (1) ◽  
pp. 321-328 ◽  
Author(s):  
Yongmei He ◽  
Xiang Li ◽  
Fangdong Zhan ◽  
Chunmei Xie ◽  
Yanqun Zu ◽  
...  
Keyword(s):  
Magnaporthe Oryzae ◽  
Physiological Response ◽  
Rice Leaves

scholarly journals Role of two metacaspases in development and pathogenicity of the Rice Blast fungus, Magnaporthe oryzae

2020 ◽  
Author(s):  
Jessie Fernandez ◽  
Victor Lopez ◽  
Lisa Kinch ◽  
Mariel A. Pfeifer ◽  
Hillery Gray ◽  
...  
Keyword(s):  
Cell Death ◽  
Food Security ◽  
Life Cycle ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Rice Blast Disease ◽  
Blast Disease ◽  
Complex Life Cycle ◽  
Insight Into

ABSTRACTRice blast disease caused by Magnaporthe oryzae is a devastating disease of cultivated rice worldwide. Infections by this fungus lead to a significant reduction in rice yields and threats to food security. To gain better insight into growth and cell death in M. oryzae during infection, we characterized two predicted M. oryzae metacaspase proteins, MoMca1 and MoMca2. These proteins appear to be functionally redundant and are able to complement the yeast Yca1 homologue. Biochemical analysis revealed that M. oryzae metacaspases exhibited Ca2+ dependent caspase activity in vitro. Deletion of both MoMca1 and MoMca2 in M. oryzae resulted in reduced sporulation, delay in conidial germination and attenuation of disease severity. In addition, the double ΔMomca1mca2 mutant strain showed increased radial growth in the presence of oxidative stress. Interestingly, the ΔMomca1mca2 strain showed an increase accumulation of insoluble aggregates compared to the wild-type strain during vegetative growth. Our findings suggest that MoMca1 and MoMca2 promote the clearance of insoluble aggregates in M. oryzae, demonstrating the important role these metacaspases have in fungal protein homeostasis. Furthermore, these metacaspase proteins may play additional roles, like in regulating stress responses, that would help maintain the fitness of fungal cells required for host infection.IMPORTANCEMagnaporthe oryzae causes rice blast disease that threatens global food security by resulting in the severe loss of rice production every year. A tightly regulated life cycle allows M. oryzae to disarm the host plant immune system during its biotrophic stage before triggering plant cell death in its necrotrophic stage. The ways M. oryzae navigates its complex life cycle remains unclear. This work characterizes two metacaspase proteins with peptidase activity in M. oryzae that are shown to be involved in the regulation of fungal growth and development prior to infection by potentially helping maintain fungal fitness. This study provides new insight into the role of metacaspase proteins in filamentous fungi by illustrating the delays in M. oryzae morphogenesis in the absence of these proteins. Understanding the mechanisms by which M. oryzae morphology and development promote its devastating pathogenicity may lead to the emergence of proper methods for disease control.

scholarly journals Stimulation of cardiac fibroblast Piezo1 channels opposes myofibroblast differentiation and induces IL-6 secretion via Ca2+-mediated p38 MAP kinase activation

2019 ◽  
Author(s):  
Nicola M. Blythe ◽  
Vasili Stylianidis ◽  
Melanie J. Ludlow ◽  
Hamish T. J. Gilbert ◽  
Elizabeth L. Evans ◽  
...  
Keyword(s):  
Map Kinase ◽  
Structural Integrity ◽  
Kinase Inhibitor ◽  
Cardiac Fibroblasts ◽  
Collagen Gel ◽  
Mechanical Stretch ◽  
Cardiac Fibroblast ◽  
Ruthenium Red ◽  
P38 Map Kinase ◽  
Dependent Manner

AbstractPiezo1 is a mechanosensitive cation channel with widespread physiological importance; however its role in the heart is poorly understood. Cardiac fibroblasts are responsible for preserving the structural integrity of the myocardium and play a key role in regulating its repair and remodeling following stress or injury. We investigated expression and function of Piezo1 in cultured human and mouse cardiac fibroblasts. RT-PCR studies confirmed expression ofPiezo1mRNA in cardiac fibroblasts at similar levels to endothelial cells. Fura-2 intracellular Ca2+measurements validated Piezo1 as a functional ion channel that was activated by the Piezo1 agonist, Yoda1. Yoda1-induced Ca2+entry was inhibited by Piezo1 blockers (gadolinium, ruthenium red) and the Ca2+response was reduced proportionally by Piezo1 siRNA knockdown or in cells fromPiezo1+/−mice. Investigation of Yoda1 effects on selected remodeling genes indicated that Piezo1 activation opposed cardiac fibroblast differentiation; data confirmed by functional collagen gel contraction assays. Piezo1 activation using Yoda1 or mechanical stretch also increased the expression of interleukin-6 (IL-6), a mechanosensitive pro-hypertrophic and pro-fibrotic cytokine, in a Piezo1-dependent manner. Multiplex kinase activity profiling combined with kinase inhibitor studies and phospho-specific western blotting, established that Piezo1 activation stimulated IL-6 secretion via a pathway involving p38 MAP kinase, downstream of Ca2+entry. In summary, this study reveals that cardiac fibroblasts express functional Piezo1 channels coupled to reduced myofibroblast activation and increased secretion of paracrine signaling molecules that can modulate cardiac remodeling.

scholarly journals Fc-dependent depletion of tumor-infiltrating regulatory T cells co-defines the efficacy of anti–CTLA-4 therapy against melanoma

2013 ◽  
Vol 210 (9) ◽  
pp. 1695-1710 ◽  
Author(s):  
Tyler R. Simpson ◽  
Fubin Li ◽  
Welby Montalvo-Ortiz ◽  
Manuel A. Sepulveda ◽  
Katharina Bergerhoff ◽  
...  
Keyword(s):  
T Cells ◽  
Cytotoxic T Lymphocyte ◽  
Tumor Regression ◽  
Cell Activity ◽  
Dependent Manner ◽  
Antitumor Effector ◽  
Tumor Environment ◽  
In Trans ◽  
Immunomodulatory Therapies ◽  
Insight Into

Treatment with monoclonal antibody specific for cytotoxic T lymphocyte–associated antigen 4 (CTLA-4), an inhibitory receptor expressed by T lymphocytes, has emerged as an effective therapy for the treatment of metastatic melanoma. Although subject to debate, current models favor a mechanism of activity involving blockade of the inhibitory activity of CTLA-4 on both effector (T eff) and regulatory (T reg) T cells, resulting in enhanced antitumor effector T cell activity capable of inducing tumor regression. We demonstrate, however, that the activity of anti–CTLA-4 antibody on the T reg cell compartment is mediated via selective depletion of T reg cells within tumor lesions. Importantly, T reg cell depletion is dependent on the presence of Fcγ receptor–expressing macrophages within the tumor microenvironment, indicating that T reg cells are depleted in trans in a context-dependent manner. Our results reveal further mechanistic insight into the activity of anti-CTLA-4–based cancer immunotherapy, and illustrate the importance of specific features of the local tumor environment on the final outcome of antibody-based immunomodulatory therapies.

Impaired Sphingosine-1-Phosphate Synthesis Induces Preeclampsia by Deactivating Trophoblastic YAP (Yes-Associated Protein) Through S1PR2 (Sphingosine-1-Phosphate Receptor-2)-Induced Actin Polymerizations

Hypertension ◽  
2021 ◽  
Author(s):  
Jiujiang Liao ◽  
Yangxi Zheng ◽  
Mingyu Hu ◽  
Ping Xu ◽  
Li Lin ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Sphingosine Kinase ◽  
Actin Dynamics ◽  
Extravillous Trophoblast ◽  
Trophoblast Invasion ◽  
Hippo Signaling ◽  
Dependent Manner ◽  
Sphingosine Kinase 1 ◽  
Sphingosine 1 Phosphate

Incomplete spiral artery remodeling, caused by impaired extravillous trophoblast invasion, is a fundamental pathogenic process associated with malplacentation and the development of preeclampsia. Nevertheless, the mechanisms controlling this regulation of trophoblast invasion are largely unknown. We report that sphingosine-1-phosphate synthesis and expression is abundant in healthy trophoblast, whereas in pregnancies complicated by preeclampsia the placentae are associated with reduced sphingosine-1-phosphate and lower SPHK1 (sphingosine kinase 1) expression and activity. In vivo inhibition of sphingosine kinase 1 activity during placentation in pregnant mice led to decreased placental sphingosine-1-phosphate production and defective placentation, resulting in a preeclampsia phenotype. Moreover, sphingosine-1-phosphate increased HTR8/SVneo (immortalized trophoblast cells) cell invasion in a Hippo-signaling–dependent transcriptional coactivator YAP (Yes-associated protein) dependent manner, which is activated by S1PR2 (sphingosine-1-phosphate receptor-2) and downstream RhoA/ROCK induced actin polymerization. Mutation-based YAP-5SA demonstrated that sphingosine-1-phosphate activation of YAP could be either dependent or independent of Hippo signaling. Together, these findings suggest a novel pathogenic pathway of preeclampsia via disrupted sphingosine-1-phosphate metabolism and signaling-induced, interrupted actin dynamics and YAP deactivation; this may lead to potential novel intervention targets for the prevention and management of preeclampsia.

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