scholarly journals FLN ‐1/filamin is required to anchor the actomyosin cytoskeleton and for global organization of sub‐cellular organelles in a contractile tissue

Cytoskeleton ◽  
2020 ◽  
Vol 77 (10) ◽  
pp. 379-398
Author(s):  
Charlotte A. Kelley ◽  
Olivia Triplett ◽  
Samyukta Mallick ◽  
Kristopher Burkewitz ◽  
William B. Mair ◽  
...  
Keyword(s):  
Global Organization ◽  
Actomyosin Cytoskeleton ◽  
Contractile Tissue ◽  
Cellular Organelles

scholarly journals FLN-1/Filamin is required to anchor the actomyosin cytoskeleton and for global organization of sub-cellular organelles in a contractile tissue

2020 ◽  
Author(s):  
Charlotte A. Kelley ◽  
Olivia Triplett ◽  
Samyukta Mallick ◽  
Kristopher Burkewitz ◽  
William B. Mair ◽  
...  
Keyword(s):  
Myoepithelial Cells ◽  
Cell Junctions ◽  
Tissue Loss ◽  
Linc Complex ◽  
Regular Array ◽  
C Elegans ◽  
Global Organization ◽  
Actomyosin Cytoskeleton ◽  
Contractile Tissue ◽  
Cellular Organelles

AbstractActomyosin networks are organized in space, direction, size, and connectivity to produce coordinated contractions across cells. We use the C. elegans spermatheca, a tube composed of contractile myoepithelial cells, to study how actomyosin structures are organized. FLN-1/filamin is required for the formation and stabilization of a regular array of parallel, contractile, actomyosin fibers in this tissue. Loss of fln-1 results in the detachment of actin fibers from the basal surface, which then accumulate along the cell junctions and are stabilized by spectrin. In addition, actin and myosin are captured at the nucleus by the linker of nucleoskeleton and cytoskeleton complex (LINC) complex, where they form large foci. Nuclear positioning and morphology, distribution of the endoplasmic reticulum and the mitochondrial network are also disrupted. These results demonstrate that filamin is required to prevent large actin bundle formation and detachment, to prevent excess nuclear localization of actin and myosin, and to ensure correct positioning of organelles.

A complex network of “snake-like tubules” revealed by the NADPase cytochemical reaction in the acinar cell of pancreas

1984 ◽  
Vol 42 ◽  
pp. 666-667
Author(s):  
A.R. Beaudoin ◽  
G. Grondin ◽  
A. Lord ◽  
M. Pelletier
Keyword(s):  
Acinar Cell ◽  
Lead Acetate ◽  
Ultrastructural Localization ◽  
Sodium Acetate Buffer ◽  
Zymogen Granules ◽  
Sprague Dawley ◽  
Dense Bodies ◽  
Sprague Dawley Rats ◽  
Cytochemical Reaction ◽  
Cellular Organelles

We have recently described the ultrastructural localization of NADPase activity in the exocrine pancreas of rat. The enzyme was found in the intermediate saccules of the Golgi apparatus, in dense bodies and lysosomes but was absent from zymogen granules. A very intense reaction was noticed in a peculiar structure which was termed “Snake-Like Tubule” (SLT). The purposes of the present study were firstly to delineate SLT distribution in the acinar cell and secondly to define any possible relationship or association with other cellular organelles.NADPase cytochemical reaction was performed on the pancreas of adult Sprague Dawley rats. Small lobules were excised and fixed for 50 min, at 4°C, in 2% glutaraldehyde buffered with 0.1M cacodylate at pH 7.2. Lobules were rinsed several times with the same buffer containing 570 sucrose and cut with a Mcllwayn tissue chopper. Sections were washed several times with buffer and incubated for 2 hr at 37°C in the following medium: 4mM NADPH; 40mM sodium acetate buffer, pH 5.0; 4mM lead acetate and 5% sucrose.

Scanning Secondary Electron Microscopy of Myofibrils Using Transmission Techniques

1975 ◽  
Vol 33 ◽  
pp. 556-557
Author(s):  
M. K. Lamvik
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Carbon Films ◽  
Photographic Recording ◽  
Transmission Electron ◽  
Thin Carbon ◽  
The Common ◽  
Scanning Electron ◽  
Better Than ◽  
Cellular Organelles

When observing small objects such as cellular organelles by scanning electron microscopy, it is often valuable to use the techniques of transmission electron microscopy. The common practice of mounting and coating for SEM may not always be necessary. These possibilities are illustrated using vertebrate skeletal muscle myofibrils.Micrographs for this study were made using a Hitachi HFS-2 scanning electron microscope, with photographic recording usually done at 60 seconds per frame. The instrument was operated at 25 kV, with a specimen chamber vacuum usually better than 10-7 torr. Myofibrils were obtained from rabbit back muscle using the method of Zak et al. To show the component filaments of this contractile organelle, the myofibrils were partially disrupted by agitation in a relaxing medium. A brief centrifugation was done to clear the solution of most of the undisrupted myofibrils before a drop was placed on the grid. Standard 3 mm transmission electron microscope grids covered with thin carbon films were used in this study.

Membrane–cytoskeleton interactions in cholesterol-dependent domain formation

2015 ◽  
Vol 57 ◽  
pp. 177-187 ◽  
Author(s):  
Jennifer N. Byrum ◽  
William Rodgers
Keyword(s):  
Biological Properties ◽  
Membrane Rafts ◽  
Membrane Domains ◽  
Biological Functions ◽  
Membrane Cytoskeleton ◽  
Heterogeneous Structures ◽  
Integral Role ◽  
Model Cell ◽  
Actomyosin Cytoskeleton ◽  
Dependent Domain

Since the inception of the fluid mosaic model, cell membranes have come to be recognized as heterogeneous structures composed of discrete protein and lipid domains of various dimensions and biological functions. The structural and biological properties of membrane domains are represented by CDM (cholesterol-dependent membrane) domains, frequently referred to as membrane ‘rafts’. Biological functions attributed to CDMs include signal transduction. In T-cells, CDMs function in the regulation of the Src family kinase Lck (p56lck) by sequestering Lck from its activator CD45. Despite evidence of discrete CDM domains with specific functions, the mechanism by which they form and are maintained within a fluid and dynamic lipid bilayer is not completely understood. In the present chapter, we discuss recent advances showing that the actomyosin cytoskeleton has an integral role in the formation of CDM domains. Using Lck as a model, we also discuss recent findings regarding cytoskeleton-dependent CDM domain functions in protein regulation.

scholarly journals Interactions between the WEE-1.3 kinase and the PAM-1 aminopeptidase in oocyte maturation and the early C. elegans embryo

2021 ◽  
Author(s):  
Dorothy Benton ◽  
Eva C Jaeger ◽  
Arielle Kilner ◽  
Ashley Kimble ◽  
Josh Lowry ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Oocyte Maturation ◽  
Protective Role ◽  
C Elegans ◽  
Direct Target ◽  
The One ◽  
Actomyosin Cytoskeleton ◽  
Embryonic Viability ◽  
Anterior Posterior

Abstract Puromycin-sensitive aminopeptidases are found across phyla and are known to regulate the cell-cycle and play a protective role in neurodegenerative disease. PAM-1 is a puromycin-sensitive aminopeptidase important for meiotic exit and polarity establishment in the one-cell Caenorhabditis elegans embryo. Despite conservation of this aminopeptidase, little is known about its targets during development. In order to identify novel interactors, we conducted a suppressor screen and isolated four suppressing mutations in three genes that partially rescued the maternal-effect lethality of pam-1 mutants. Suppressed strains show improved embryonic viability and polarization of the anterior-posterior axis. We identified a missense mutation in wee-1.3 in one of these suppressed strains. WEE-1.3 is an inhibitory kinase that regulates maturation promoting factor. While the missense mutation suppressed polarity phenotypes in pam-1, it does so without restoring centrosome-cortical contact or altering the cortical actomyosin cytoskeleton. To see if PAM-1 and WEE-1.3 interact in other processes, we examined oocyte maturation. While depletion of wee-1.3 causes sterility due to precocious oocyte maturation, this effect was lessened in pam-1 worms, suggesting that PAM-1 and WEE-1.3 interact in this process. Levels of WEE-1.3 were comparable between wild-type and pam-1 strains, suggesting that WEE-1.3 is not a direct target of the aminopeptidase. Thus, we have established an interaction between PAM-1 and WEE-1.3 in multiple developmental processes and have identified suppressors that are likely to further our understanding of the role of puromycin-sensitive aminopeptidases during development.

scholarly journals Antiviral, Antibacterial, Antifungal, and Antiparasitic Properties of Propolis: A Review

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1360
Author(s):  
Felix Zulhendri ◽  
Kavita Chandrasekaran ◽  
Magdalena Kowacz ◽  
Munir Ravalia ◽  
Krishna Kripal ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Antioxidant Status ◽  
Energy Production ◽  
Mechanisms Of Action ◽  
Host Cells ◽  
Physical Barrier ◽  
Inflammatory Signaling ◽  
Replication Process ◽  
Comprehensive Review ◽  
Cellular Organelles

Propolis is a complex phytocompound made from resinous and balsamic material harvested by bees from flowers, branches, pollen, and tree exudates.Humans have used propolis therapeutically for centuries. The aim of this article is to provide comprehensive review of the antiviral, antibacterial, antifungal, and antiparasitic properties of propolis. The mechanisms of action of propolis are discussed. There are two distinct impacts with regards to antimicrobial and anti-parasitic properties of propolis, on the pathogens and on the host. With regards to the pathogens, propolis acts by disrupting the ability of the pathogens to invade the host cells by forming a physical barrier and inhibiting enzymes and proteins needed for invasion into the host cells. Propolis also inhibits the replication process of the pathogens. Moreover, propolis inhibits the metabolic processes of the pathogens by disrupting cellular organelles and components responsible for energy production. With regard to the host, propolis functions as an immunomodulator. It upregulates the innate immunity and modulates the inflammatory signaling pathways. Propolis also helps maintain the host’s cellular antioxidant status. More importantly, a small number of human clinical trials have demonstrated the efficacy and the safety of propolis as an adjuvant therapy for pathogenic infections.

scholarly journals Ras Isoforms from Lab Benches to Lives—What Are We Missing and How Far Are We?

2021 ◽  
Vol 22 (12) ◽  
pp. 6508
Author(s):  
Arathi Nair ◽  
Katharina F. Kubatzky ◽  
Bhaskar Saha
Keyword(s):  
Protein Isoforms ◽  
Initial Assessment ◽  
Cell Type ◽  
Ras Genes ◽  
Ras Gtpase ◽  
Central Protein ◽  
Preferential Localization ◽  
Functional Map ◽  
Ras Isoforms ◽  
Cellular Organelles

The central protein in the oncogenic circuitry is the Ras GTPase that has been under intense scrutiny for the last four decades. From its discovery as a viral oncogene and its non–oncogenic contribution to crucial cellular functioning, an elaborate genetic, structural, and functional map of Ras is being created for its therapeutic targeting. Despite decades of research, there still exist lacunae in our understanding of Ras. The complexity of the Ras functioning is further exemplified by the fact that the three canonical Ras genes encode for four protein isoforms (H-Ras, K-Ras4A, K-Ras4B, and N-Ras). Contrary to the initial assessment that the H-, K-, and N-Ras isoforms are functionally similar, emerging data are uncovering crucial differences between them. These Ras isoforms exhibit not only cell–type and context-dependent functions but also activator and effector specificities on activation by the same receptor. Preferential localization of H-, K-, and N-Ras in different microdomains of the plasma membrane and cellular organelles like Golgi, endoplasmic reticulum, mitochondria, and endosome adds a new dimension to isoform-specific signaling and diverse functions. Herein, we review isoform-specific properties of Ras GTPase and highlight the importance of considering these towards generating effective isoform-specific therapies in the future.

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