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Journal of Cell Science Jul 2014Centrioles and basal bodies (CBBs) are microtubule-rich cylindrical structures that nucleate and organize centrosomes and cilia, respectively. Despite their apparent... (Review)
Review
Centrioles and basal bodies (CBBs) are microtubule-rich cylindrical structures that nucleate and organize centrosomes and cilia, respectively. Despite their apparent ninefold rotational symmetry, the nine sets of triplet microtubules in CBBs possess asymmetries in their morphology and in the structures that associate with them. These asymmetries define the position of nascent CBB assembly, the orientation of ciliary beating, the orientation of spindle poles and the maintenance of cellular geometry. For some of these functions, the orientation of CBBs is first established during new CBB biogenesis when the daughter structure is positioned adjacent to the mother. The mother CBB organizes the surrounding environment that nascent CBBs are born into, thereby providing a nest for the new CBB to develop. Protists, including ciliates and algae, highlight the importance of this environment with the formation of asymmetrically placed scaffolds onto which new basal bodies assemble and are positioned. Recent studies illuminate the positioning of nascent centrioles relative to a modular pericentriolar material (PCM) environment and suggest that, like ciliates, centrosomes organize an immediate environment surrounding centrioles for their biogenesis and positioning. In this Commentary, I will explore the positioning of nascent CBB assembly as the first event in building cellular asymmetries and describe how the environment surrounding both basal bodies and centrioles may define asymmetric assembly.
Topics: Animals; Basal Bodies; Centrioles; Humans; Microtubules
PubMed: 24895399
DOI: 10.1242/jcs.151761 -
Cilia 2016The unicellular green alga, Chlamydomonas reinhardtii, is a biflagellated cell that can swim or glide. C. reinhardtii cells are amenable to genetic, biochemical,... (Review)
Review
The unicellular green alga, Chlamydomonas reinhardtii, is a biflagellated cell that can swim or glide. C. reinhardtii cells are amenable to genetic, biochemical, proteomic, and microscopic analysis of its basal bodies. The basal bodies contain triplet microtubules and a well-ordered transition zone. Both the mother and daughter basal bodies assemble flagella. Many of the proteins found in other basal body-containing organisms are present in the Chlamydomonas genome, and mutants in these genes affect the assembly of basal bodies. Electron microscopic analysis shows that basal body duplication is site-specific and this may be important for the proper duplication and spatial organization of these organelles. Chlamydomonas is an excellent model for the study of basal bodies as well as the transition zone.
PubMed: 27252853
DOI: 10.1186/s13630-016-0039-z -
Seminars in Cell & Developmental Biology Feb 2021Multiciliated cells (MCC) project dozens to hundreds of motile cilia from the cell surface to generate fluid flow across epithelial surfaces or turbulence to promote the... (Review)
Review
Multiciliated cells (MCC) project dozens to hundreds of motile cilia from the cell surface to generate fluid flow across epithelial surfaces or turbulence to promote the transport of gametes. The MCC differentiation program is initiated by GEMC1 and MCIDAS, members of the geminin family, that activate key transcription factors, including p73 and FOXJ1, to control the multiciliogenesis program. To support the generation of multiple motile cilia, MCCs must undergo massive centriole amplification to generate a sufficient number of basal bodies (modified centrioles). This transcriptional program involves the generation of deuterosomes, unique structures that act as platforms to regulate centriole amplification, the reactivation of cell cycle programs to control centriole amplification and release, and extensive remodeling of the cytoskeleton. This review will focus on providing an overview of the transcriptional regulation of MCCs and its connection to key processes, in addition to highlighting exciting recent developments and open questions in the field.
Topics: Animals; Cell Cycle; Cell Cycle Proteins; Cell Differentiation; Centrioles; Cilia; Ciliopathies; Cytoskeleton; Forkhead Transcription Factors; Gene Expression Regulation; Humans; Signal Transduction; Transcription Factors; Transcription, Genetic; Tumor Protein p73
PubMed: 32362381
DOI: 10.1016/j.semcdb.2020.04.007 -
Cilia 2016Phylum choanoflagellata is the nearest unicellular neighbor of metazoa at the phylogenetic tree. They are single celled or form the colonies, can be presented by naked... (Review)
Review
Phylum choanoflagellata is the nearest unicellular neighbor of metazoa at the phylogenetic tree. They are single celled or form the colonies, can be presented by naked cells or live in theca or lorica, but in all cases they have a flagellum surrounded by microvilli of the collar. They have rather uniform and peculiar flagellar apparatus structure with flagellar basal body (FB) producing a flagellum, and non-flagellar basal body (NFB) lying orthogonal to the FB. Long flagellar transition zone contains a unique structure among eukaryotes, the central filament, which connects central microtubules to the transversal plate. Both basal bodies are composed of triplets and interconnected with fibrillar bridge. They also contain the internal arc-shaped connectives between the triplets. The FB has prominent transitional fibers similar to those of chytrid zoospores and choanocytes of sponges, and a radial microtubular root system. The ring-shaped microtubule organizing center (MTOC) produces radial root microtubules, but in some species a MTOC is represented by separate foci. The NFB has a narrow fibrillar root directed towards the Golgi apparatus in association with membrane-bounded sac. Prior to cell division, the basal bodies replicate and migrate to poles of elongated nucleus. The basal bodies serve as MTOCs for the spindle microtubules during nuclear division by semiopen orthomitosis.
PubMed: 27148446
DOI: 10.1186/s13630-016-0033-5 -
Cold Spring Harbor Perspectives in... Feb 2015The centrosome was discovered in the late 19th century when mitosis was first described. Long recognized as a key organelle of the spindle pole, its core component, the... (Review)
Review
The centrosome was discovered in the late 19th century when mitosis was first described. Long recognized as a key organelle of the spindle pole, its core component, the centriole, was realized more than 50 or so years later also to comprise the basal body of the cilium. Here, we chart the more recent acquisition of a molecular understanding of centrosome structure and function. The strategies for gaining such knowledge were quickly developed in the yeasts to decipher the structure and function of their distinctive spindle pole bodies. Only within the past decade have studies with model eukaryotes and cultured cells brought a similar degree of sophistication to our understanding of the centrosome duplication cycle and the multiple roles of this organelle and its component parts in cell division and signaling. Now as we begin to understand these functions in the context of development, the way is being opened up for studies of the roles of centrosomes in human disease.
Topics: Animals; Centrosome; Cilia; Drosophila; Drosophila Proteins; Humans; Mice; Mitosis; Models, Biological; Protein Serine-Threonine Kinases; S Phase; Saccharomycetales; Spindle Apparatus; Xenopus laevis
PubMed: 25646378
DOI: 10.1101/cshperspect.a015800 -
Philosophical Transactions of the Royal... Dec 2016Self-assembly of two important components of the cytoskeleton of eukaryotic cells, actin microfilaments and microtubules (MTs) results in polar filaments of one... (Review)
Review
Self-assembly of two important components of the cytoskeleton of eukaryotic cells, actin microfilaments and microtubules (MTs) results in polar filaments of one chirality. As is true for bacterial flagella, in actin microfilaments, screw direction is important for assembly processes and motility. For MTs, polar orientation within the cell is paramount. The alignment of these elements in the cell cytoplasm gives rise to emergent properties, including the potential for cell differentiation and specialization. Complex MTs with a characteristic chirality are found in basal bodies and centrioles; this chirality is preserved in cilia. In motile cilia, it is reflected in the direction of the effective stroke. The positioning of the basal body or cilia on the cell surface depends on polarity proteins. In evolution, survival depends on global polarity information relayed to the cell in part by orientation of the MT and actin filament cytoskeletons and the chirality of the basal body to determine left and right coordinates within a defined anterior-posterior cell and tissue axis.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.
Topics: Actin Cytoskeleton; Biological Evolution; Cytoskeleton; Eukaryotic Cells; Microtubules
PubMed: 27821520
DOI: 10.1098/rstb.2015.0408 -
Genetics May 2017Centrioles play a key role in the development of the fly. They are needed for the correct formation of centrosomes, the organelles at the poles of the spindle that can... (Review)
Review
Centrioles play a key role in the development of the fly. They are needed for the correct formation of centrosomes, the organelles at the poles of the spindle that can persist as microtubule organizing centers (MTOCs) into interphase. The ability to nucleate cytoplasmic microtubules (MTs) is a property of the surrounding pericentriolar material (PCM). The centriole has a dual life, existing not only as the core of the centrosome but also as the basal body, the structure that templates the formation of cilia and flagellae. Thus the structure and functions of the centriole, the centrosome, and the basal body have an impact upon many aspects of development and physiology that can readily be modeled in Centrosomes are essential to give organization to the rapidly increasing numbers of nuclei in the syncytial embryo and for the spatially precise execution of cell division in numerous tissues, particularly during male meiosis. Although mitotic cell cycles can take place in the absence of centrosomes, this is an error-prone process that opens up the fly to developmental defects and the potential of tumor formation. Here, we review the structure and functions of the centriole, the centrosome, and the basal body in different tissues and cultured cells of , highlighting their contributions to different aspects of development and cell division.
Topics: Animals; Basal Bodies; Centrioles; Centrosome; Cilia; Drosophila melanogaster; Meiosis; Microtubules
PubMed: 28476861
DOI: 10.1534/genetics.116.198168 -
Cells Jul 2018During ciliogenesis, centrioles convert to membrane-docked basal bodies, which initiate the formation of cilia/flagella and template the nine doublet microtubules of the... (Review)
Review
During ciliogenesis, centrioles convert to membrane-docked basal bodies, which initiate the formation of cilia/flagella and template the nine doublet microtubules of the flagellar axoneme. The discovery that many human diseases and developmental disorders result from defects in flagella has fueled a strong interest in the analysis of flagellar assembly. Here, we will review the structure, function, and development of basal bodies in the unicellular green alga , a widely used model for the analysis of basal bodies and flagella. Intraflagellar transport (IFT), a flagella-specific protein shuttle critical for ciliogenesis, was first described in A focus of this review will be on the role of the basal bodies in organizing the IFT machinery.
PubMed: 30018231
DOI: 10.3390/cells7070079 -
Cilia 2017The free-living nematode, , is a widely used genetic model organism for investigations into centriole and cilia biology. Only sensory neurons are ciliated in ;... (Review)
Review
The free-living nematode, , is a widely used genetic model organism for investigations into centriole and cilia biology. Only sensory neurons are ciliated in ; morphologically diverse cilia in these neurons are nucleated by basal bodies located at the dendritic endings. centrioles comprise a central tube with a symmetric array of nine singlet microtubules. These singlet microtubules remodel in a subset of sensory neurons to form the doublet microtubules of the basal bodies. Following initiation of ciliogenesis, the central tube, but not the outer centriole wall, of the basal body degenerates. Recent ultrastructural characterization of basal body architecture and remodeling have laid the foundation for future studies into mechanisms underlying different aspects of basal body genesis, remodeling, and intracellular positioning.
PubMed: 28770089
DOI: 10.1186/s13630-017-0053-9 -
Cilia 2016The fruit fly, Drosophila melanogaster, is one of the most extensively studied organisms in biological research and has centrioles/basal bodies and cilia that can be... (Review)
Review
The fruit fly, Drosophila melanogaster, is one of the most extensively studied organisms in biological research and has centrioles/basal bodies and cilia that can be modelled to investigate their functions in animals generally. Centrioles are nine-fold symmetrical microtubule-based cylindrical structures required to form centrosomes and also to nucleate the formation of cilia and flagella. When they function to template cilia, centrioles transition into basal bodies. The fruit fly has various types of basal bodies and cilia, which are needed for sensory neuron and sperm function. Genetics, cell biology and behaviour studies in the fruit fly have unveiled new basal body components and revealed different modes of assembly and functions of basal bodies that are conserved in many other organisms, including human, green algae and plasmodium. Here we describe the various basal bodies of Drosophila, what is known about their composition, structure and function.
PubMed: 27382461
DOI: 10.1186/s13630-016-0041-5