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Journal of Muscle Research and Cell... Mar 2020The interactions of cytoskeletal actin filaments with myosin family motors are essential for the integrity and function of eukaryotic cells. They support a wide range of... (Review)
Review
The interactions of cytoskeletal actin filaments with myosin family motors are essential for the integrity and function of eukaryotic cells. They support a wide range of force-dependent functions. These include mechano-transduction, directed transcellular transport processes, barrier functions, cytokinesis, and cell migration. Despite the indispensable role of tropomyosins in the generation and maintenance of discrete actomyosin-based structures, the contribution of individual cytoskeletal tropomyosin isoforms to the structural and functional diversification of the actin cytoskeleton remains a work in progress. Here, we review processes that contribute to the dynamic sorting and targeted distribution of tropomyosin isoforms in the formation of discrete actomyosin-based structures in animal cells and their effects on actin-based motility and contractility.
Topics: Actins; Humans; Tropomyosin
PubMed: 31054005
DOI: 10.1007/s10974-019-09514-0 -
Bioscience Reports Sep 2022Cell homeostasis is maintained in all organisms by the constant adjustment of cell constituents and organisation to account for environmental context. Fine-tuning of the... (Review)
Review
Cell homeostasis is maintained in all organisms by the constant adjustment of cell constituents and organisation to account for environmental context. Fine-tuning of the optimal balance of proteins for the conditions, or protein homeostasis, is critical to maintaining cell homeostasis. Actin, a major constituent of the cytoskeleton, forms many different structures which are acutely sensitive to the cell environment. Furthermore, actin structures interact with and are critically important for the function and regulation of multiple factors involved with mRNA and protein production and degradation, and protein regulation. Altogether, actin is a key, if often overlooked, regulator of protein homeostasis across eukaryotes. In this review, we highlight these roles and how they are altered following cell stress, from mRNA transcription to protein degradation.
Topics: Actin Cytoskeleton; Actins; Cytoskeleton; Homeostasis; Proteostasis; RNA, Messenger
PubMed: 36043949
DOI: 10.1042/BSR20210848 -
Journal of Muscle Research and Cell... Mar 2020ADF/cofilins disassemble the actin filament and contribute to a wide range of actin dynamics. These proteins are regulated by several factors, including phosphorylation,... (Review)
Review
ADF/cofilins disassemble the actin filament and contribute to a wide range of actin dynamics. These proteins are regulated by several factors, including phosphorylation, pH and mechanical forces. Although the cofilin-decorated actin filament structure was published recently, the mechanisms of these regulating factors remain unclear. Models that describe regulation based on the latest structural data and research will be discussed. Aspects about the interaction between actin and cofilin that require further investigation are also discussed.
Topics: Actin Depolymerizing Factors; Actins; Humans; Models, Molecular
PubMed: 31346850
DOI: 10.1007/s10974-019-09546-6 -
Physical Biology Feb 2022Cytoskeletal proteins are classified as a group that is defined functionally, whose members are capable of polymerizing into higher order structures, either dynamically... (Review)
Review
Cytoskeletal proteins are classified as a group that is defined functionally, whose members are capable of polymerizing into higher order structures, either dynamically or statically, to perform structural roles during a variety of cellular processes. In eukaryotes, the most well-studied cytoskeletal proteins are actin, tubulin, and intermediate filaments, and are essential for cell shape and movement, chromosome segregation, and intracellular cargo transport. Prokaryotes often harbor homologs of these proteins, but in bacterial cells, these homologs are usually not employed in roles that can be strictly defined as 'cytoskeletal'. However, several bacteria encode other proteins capable of polymerizing which, although they do not appear to have a eukaryotic counterpart, nonetheless appear to perform a more traditional 'cytoskeletal' function. In this review, we discuss recent reports that cover the structures and functions of prokaryotic proteins that are broadly termed as cytoskeletal, either by sequence homology or by function, to highlight how the enzymatic properties of traditionally studied cytoskeletal proteins may be used for other types of cellular functions; and to demonstrate how truly 'cytoskeletal' functions may be performed by uniquely bacterial proteins that do not display homology to eukaryotic proteins.
Topics: Actins; Bacteria; Bacterial Proteins; Cytoskeletal Proteins; Cytoskeleton
PubMed: 35081523
DOI: 10.1088/1478-3975/ac4ef0 -
Current Opinion in Genetics &... Oct 2019The actin cytoskeleton governs a vast array of core eukaryotic phenotypes that include cell movement, endocytosis, vesicular trafficking, and cytokinesis. Although the... (Review)
Review
The actin cytoskeleton governs a vast array of core eukaryotic phenotypes that include cell movement, endocytosis, vesicular trafficking, and cytokinesis. Although the basic principle underlying these processes is strikingly simple - actin monomers polymerize into filaments that can depolymerize back into monomers - eukaryotic cells have sophisticated and layered control systems to regulate actin dynamics. The evolutionary origin of these complex systems is an area of active research. Here, we review the regulation and diversity of actin networks to provide a conceptual framework for cell biologists interested in evolution and for evolutionary biologists interested in actin-dependent phenotypes.
Topics: Actin Cytoskeleton; Actins; Archaea; Chlamydomonas; Cytokinesis; Endocytosis; Evolution, Molecular; Flagella; Fungi; Genomics; Naegleria; Phenotype; Phylogeny; Signal Transduction
PubMed: 31466039
DOI: 10.1016/j.gde.2019.07.016 -
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 -
The International Journal of... Dec 2020Primary cilia are microtubule-based sensory cell organelles that are vital for tissue and organ development. They act as an antenna, receiving and transducing signals,... (Review)
Review
Primary cilia are microtubule-based sensory cell organelles that are vital for tissue and organ development. They act as an antenna, receiving and transducing signals, enabling communication between cells. Defects in ciliogenesis result in severe genetic disorders collectively termed ciliopathies. In recent years, the importance of the direct and indirect involvement of actin regulators in ciliogenesis came into focus as it was shown that F-actin polymerisation impacts ciliation. The ciliary basal body was further identified as both a microtubule and actin organising centre. In the current review, we summarize recent studies on F-actin in and around primary cilia, focusing on different actin regulators and their effect on ciliogenesis, from the initial steps of basal body positioning and regulation of ciliary assembly and disassembly. Since primary cilia are also involved in several intracellular signalling pathways such as planar cell polarity (PCP), subsequently affecting actin rearrangements, the multiple effectors of this pathway are highlighted in more detail with a focus on the feedback loops connecting actin networks and cilia proteins. Finally, we elucidate the role of actin regulators in the development of ciliopathy symptoms and cancer.
Topics: Actins; Animals; Cilia; Feedback, Physiological; Humans
PubMed: 33166678
DOI: 10.1016/j.biocel.2020.105877 -
ACS Synthetic Biology Oct 2022One of the major challenges of bottom-up synthetic biology is rebuilding a minimal cell division machinery. From a reconstitution perspective, the animal cell division... (Review)
Review
One of the major challenges of bottom-up synthetic biology is rebuilding a minimal cell division machinery. From a reconstitution perspective, the animal cell division apparatus is mechanically the simplest and therefore attractive to rebuild. An actin-based ring produces contractile force to constrict the membrane. By contrast, microbes and plant cells have a cell wall, so division requires concerted membrane constriction and cell wall synthesis. Furthermore, reconstitution of the actin division machinery helps in understanding the physical and molecular mechanisms of cytokinesis in animal cells and thus our own cells. In this review, we describe the state-of-the-art research on reconstitution of minimal actin-mediated cytokinetic machineries. Based on the conceptual requirements that we obtained from the physics of the shape changes involved in cell division, we propose two major routes for building a minimal actin apparatus capable of division. Importantly, we acknowledge both the passive and active roles that the confining lipid membrane can play in synthetic cytokinesis. We conclude this review by identifying the most pressing challenges for future reconstitution work, thereby laying out a roadmap for building a synthetic cell equipped with a minimal actin division machinery.
Topics: Animals; Actomyosin; Actins; Artificial Cells; Cytokinesis; Lipids
PubMed: 36164967
DOI: 10.1021/acssynbio.2c00287 -
Molecular Biology and Evolution Feb 2022The emergence of the eukaryotic cytoskeleton is a critical yet puzzling step of eukaryogenesis. Actin and actin-related proteins (ARPs) are ubiquitous components of this...
The emergence of the eukaryotic cytoskeleton is a critical yet puzzling step of eukaryogenesis. Actin and actin-related proteins (ARPs) are ubiquitous components of this cytoskeleton. The gene repertoire of the Last Eukaryotic Common Ancestor (LECA) would have therefore harbored both actin and various ARPs. Here, we report the presence and expression of actin-related genes in viral genomes (viractins) of some Imitervirales, a viral order encompassing the giant Mimiviridae. Phylogenetic analyses suggest an early recruitment of an actin-related gene by viruses from ancient protoeukaryotic hosts before the emergence of modern eukaryotes, possibly followed by a back transfer that gave rise to eukaryotic actins. This supports a coevolutionary scenario between pre-LECA lineages and their viruses, which could have contributed to the emergence of the modern eukaryotic cytoskeleton.
Topics: Actins; Eukaryota; Eukaryotic Cells; Evolution, Molecular; Giant Viruses; Phylogeny
PubMed: 35150280
DOI: 10.1093/molbev/msac022 -
International Review of Cell and... 2021The actin cytoskeleton is a dynamic network that regulates cellular behavior from development to disease. By rearranging the actin cytoskeleton, cells are capable of... (Review)
Review
The actin cytoskeleton is a dynamic network that regulates cellular behavior from development to disease. By rearranging the actin cytoskeleton, cells are capable of migrating and invading during developmental processes; however, many of these cellular properties are hijacked by cancer cells to escape primary tumors and disseminate to distant organs in the body. In this review article, we highlight recent work describing how cancer cells regulate the actin cytoskeleton to achieve efficient invasion and metastatic colonization. We also review new imaging technologies that are capable of revealing the complex architecture and regulation of the actin cytoskeleton during motility and invasion of tumor cells.
Topics: Actins; Animals; Cell Cycle; Cell Movement; Epithelial-Mesenchymal Transition; Humans; Neoplasm Metastasis; Neoplasms
PubMed: 33962751
DOI: 10.1016/bs.ircmb.2020.09.004