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Current Opinion in Immunology Oct 2021The application of high and super-resolution microscopy techniques has extended the possibilities of studying actin dynamics in mast cells (MCs). These studies... (Review)
Review
The application of high and super-resolution microscopy techniques has extended the possibilities of studying actin dynamics in mast cells (MCs). These studies demonstrated the close correlation between actin-driven changes in cell morphology and the functions that MC perform during their life cycle. Dynamic conversions between actin polymerization and depolymerization support MC degranulation and leading to the release of the preformed, secretory granule (SG)-contained, inflammatory mediators. Cell flattening inflicting an actin porous geometry and clearing of cortical actin, characterize the secretory actin phenotype. In contrast, pericentral actin clusters, that entrap the SGs, characterize the migratory actin phenotype, which supports MC migration, but restricts MC degranulation. Multiple actin binding and actin interacting proteins regulate these actin rearrangements, in compliance with the signals elicited by the respective activating receptors. Here, we review recent findings on the interplay between the actin cytoskeleton and MC migration and degranulation.
Topics: Actin Cytoskeleton; Animals; Carrier Proteins; Cell Degranulation; Cell Movement; Humans; Immunomodulation; Mast Cells; Protein Binding; Protein Multimerization; Secretory Vesicles
PubMed: 33765561
DOI: 10.1016/j.coi.2021.03.002 -
Methods in Molecular Biology (Clifton,... 2023The actin cytoskeleton is a highly dynamic network in plant cells, which is precisely regulated by numerous actin-binding proteins. Hence, characterizing the biochemical...
The actin cytoskeleton is a highly dynamic network in plant cells, which is precisely regulated by numerous actin-binding proteins. Hence, characterizing the biochemical activities of actin-binding proteins is of great importance. Here we describe methods for determining the binding and bundling of microfilaments as well as methods for visualizing microfilaments using fluorescent phalloidin and single-molecule TIRF imaging.
Topics: Actins; Actin Cytoskeleton; Microfilament Proteins; Coloring Agents; Phalloidine
PubMed: 36773222
DOI: 10.1007/978-1-0716-2867-6_2 -
Science (New York, N.Y.) Sep 2022Protein synthesis generally starts with a methionine that is removed during translation. However, cytoplasmic actin defies this rule because its synthesis involves...
Protein synthesis generally starts with a methionine that is removed during translation. However, cytoplasmic actin defies this rule because its synthesis involves noncanonical excision of the acetylated methionine by an unidentified enzyme after translation. Here, we identified C19orf54, named ACTMAP (actin maturation protease), as this enzyme. Its ablation resulted in viable mice in which the cytoskeleton was composed of immature actin molecules across all tissues. However, in skeletal muscle, the lengths of sarcomeric actin filaments were shorter, muscle function was decreased, and centralized nuclei, a common hallmark of myopathies, progressively accumulated. Thus, ACTMAP encodes the missing factor required for the synthesis of mature actin and regulates specific actin-dependent traits in vivo.
Topics: Actin Cytoskeleton; Actins; Animals; Endopeptidases; Methionine; Mice; Peptide Hydrolases
PubMed: 36173861
DOI: 10.1126/science.abq5082 -
Gene Jun 2020Spermatogenesis is a highly complex physiological process which contains spermatogonia proliferation, spermatocyte meiosis and spermatid morphogenesis. In the past... (Review)
Review
Spermatogenesis is a highly complex physiological process which contains spermatogonia proliferation, spermatocyte meiosis and spermatid morphogenesis. In the past decade, actin binding proteins and signaling pathways which are critical for regulating the actin cytoskeleton in testis had been found. In this review, we summarized 5 actin-binding proteins that have been proven to play important roles in the seminiferous epithelium. Lack of them perturbs spermatids polarity and the transport of spermatids. The loss of Arp2/3 complex, Formin1, Eps8, Palladin and Plastin3 cause sperm release failure suggesting their irreplaceable role in spermatogenesis. Actin regulation relies on multiple signal pathways. The PI3K/Akt signaling pathway positively regulate the mTOR pathway to promote actin reorganization in seminiferous epithelium. Conversely, TSC1/TSC2 complex, the upstream of mTOR, is activated by the LKB1/AMPK pathway to inhibit cell proliferation, differentiation and migration. The increasing researches focus on the function of actin binding proteins (ABPs), however, their collaborative regulation of actin patterns and potential regulatory signaling networks remains unclear. We reviewed ABPs that play important roles in mammalian spermatogenesis and signal pathways involved in the regulation of microfilaments. We suggest that more relevant studies should be performed in the future.
Topics: AMP-Activated Protein Kinases; Actin Cytoskeleton; Actins; Animals; Humans; Male; Mice; Microfilament Proteins; Phosphatidylinositol 3-Kinases; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins c-akt; Rats; Signal Transduction; Spermatogenesis
PubMed: 32244053
DOI: 10.1016/j.gene.2020.144635 -
Cells Jul 2020Podocytes are an integral part of the glomerular filtration barrier, a structure that prevents filtration of large proteins and macromolecules into the urine. Podocyte... (Review)
Review
Podocytes are an integral part of the glomerular filtration barrier, a structure that prevents filtration of large proteins and macromolecules into the urine. Podocyte function is dependent on actin cytoskeleton regulation within the foot processes, structures that link podocytes to the glomerular basement membrane. Actin cytoskeleton dynamics in podocyte foot processes are complex and regulated by multiple proteins and other factors. There are two key signal integration and structural hubs within foot processes that regulate the actin cytoskeleton: the slit diaphragm and focal adhesions. Both modulate actin filament extension as well as foot process mobility. No matter what the initial cause, the final common pathway of podocyte damage is dysregulation of the actin cytoskeleton leading to foot process retraction and proteinuria. Disruption of the actin cytoskeleton can be due to acquired causes or to genetic mutations in key actin regulatory and signaling proteins. Here, we describe the major structural and signaling components that regulate the actin cytoskeleton in podocytes as well as acquired and genetic causes of actin dysregulation.
Topics: Actin Cytoskeleton; Actins; Animals; Disease; Focal Adhesions; Humans; Mutation; Podocytes
PubMed: 32708597
DOI: 10.3390/cells9071700 -
Seminars in Cell & Developmental Biology Jun 2020One of the best known features of actin filaments is their helical structure. A number of essential properties emerge from this molecular arrangement of actin subunits.... (Review)
Review
One of the best known features of actin filaments is their helical structure. A number of essential properties emerge from this molecular arrangement of actin subunits. Here, we give an overview of the mechanical and biochemical implications of filament helicity, at different scales. In particular, a number of recent studies have highlighted the role of filament helicity in the adaptation to and the generation of mechanical torsion, and in the modulation of the filament's interaction with very different actin-binding proteins (such as myosins, cross-linkers, formins, and cofilin). Helicity can thus be seen as a key factor for the regulation of actin assembly, and as a link between biochemical regulators and their mechanical context. In addition, actin filament helicity appears to play an essential role in the establishment of chirality at larger scales, up to the organismal scale. Altogether, helicity appears to be an essential feature contributing to the regulation of actin assembly dynamics, and to actin's ability to organize cells at a larger scale.
Topics: Actin Cytoskeleton; Animals; Humans
PubMed: 31862222
DOI: 10.1016/j.semcdb.2019.10.018 -
Neurochemical Research Mar 2020Myelinating cells of both the peripheral and central nervous systems (CNSs) undergo dramatic cytoskeletal reorganization in order to differentiate and produce myelin.... (Review)
Review
Myelinating cells of both the peripheral and central nervous systems (CNSs) undergo dramatic cytoskeletal reorganization in order to differentiate and produce myelin. Myelinating oligodendrocytes in the CNS show a periodic actin pattern, demonstrating tight regulation of actin. Furthermore, recent data demonstrate that actin polymerization drives early cell differentiation and that actin depolymerization drives myelin wrapping. Dysregulation of the actin cytoskeleton in myelinating cells is seen in some disease states. This review highlights the cytoskeletal molecules that regulate differentiation of and myelination by cells of the PNS and CNS, informing our understanding of neural development, in particular myelination.
Topics: Actin Cytoskeleton; Animals; Cell Differentiation; Central Nervous System; Humans; Myelin Sheath; Oligodendroglia
PubMed: 30847860
DOI: 10.1007/s11064-019-02753-0 -
Journal of Cell Science May 2021Dynamic remodeling of the actin cytoskeleton is an essential feature for virtually all actin-dependent cellular processes, including cell migration, cell cycle... (Review)
Review
Dynamic remodeling of the actin cytoskeleton is an essential feature for virtually all actin-dependent cellular processes, including cell migration, cell cycle progression, chromatin remodeling and gene expression, and even the DNA damage response. An altered actin cytoskeleton is a structural hallmark associated with numerous pathologies ranging from cardiovascular diseases to immune disorders, neurological diseases and cancer. The actin cytoskeleton in cells is regulated through the orchestrated actions of a myriad of actin-binding proteins. In this Review, we provide a brief overview of the structure and functions of the actin-monomer-binding protein profilin-1 (Pfn1) and then discuss how dysregulated expression of Pfn1 contributes to diseases associated with the cardiovascular system.
Topics: Actin Cytoskeleton; Actins; Cardiovascular Diseases; Humans; Microfilament Proteins; Profilins
PubMed: 33961053
DOI: 10.1242/jcs.249060 -
Small GTPases 2021Cell invasion is associated with numerous patho-physiologic states including cell development and metastatic dissemination. This process couples the activation of cell... (Review)
Review
Cell invasion is associated with numerous patho-physiologic states including cell development and metastatic dissemination. This process couples the activation of cell motility with the capacity to degrade the extracellular matrix, thereby permitting cells to pass through basal membranes. Invasion is sustained by the actions of invadosomes, an ensemble of subcellular structures with high functional homology. Invadosomes are 3D acto-adhesive structures that can also mediate local extracellular matrix degradation through the controlled delivery of proteases. Intracellular RHO GTPases play a central role in the regulation of invadosomes where their complex interplay regulates multiple invadosome functions. This review aims to provide an overview of the synergistic activities of the small GTPases in invadosome biology. This broad-based review also reinforces the importance of the spatiotemporal regulation of small GTPases and the impact of this process on invadosome dynamics.
Topics: Actin Cytoskeleton; Animals; Cell Movement; Extracellular Matrix; Humans; Monomeric GTP-Binding Proteins; Podosomes
PubMed: 33487105
DOI: 10.1080/21541248.2021.1877081 -
Biochemical Society Transactions Dec 2022The lumen of cytoplasmic microtubules is a poorly explored expanse of intracellular space. Although typically represented in textbooks as a hollow tube, studies over... (Review)
Review
The lumen of cytoplasmic microtubules is a poorly explored expanse of intracellular space. Although typically represented in textbooks as a hollow tube, studies over several decades have shown that the microtubule lumen is occupied by a range of morphologically diverse components. These are predominantly globular particles of varying sizes which appear to exist either in isolation, bind to the microtubule wall, or form discontinuous columns that extend through the lumenal space. Actin filaments with morphologies distinct from the canonical cytoplasmic forms have also now been found within the microtubule lumen. In this review, we examine the historic literature that observed these lumenal components in tissues from diverse species and integrate it with recent cryo-electron tomography studies that have begun to identify lumenal proteins. We consider their cell and tissue distribution, possible mechanisms of incorporation, and potential functions. It is likely that continuing work in this area will open a new frontier in cytoskeletal biology.
Topics: Microtubules; Cytoskeleton; Actin Cytoskeleton; Cytoplasm
PubMed: 36524962
DOI: 10.1042/BST20220851