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Development (Cambridge, England) Jan 2024Cilia are microtubule (MT)-based organelles present on the surface of nearly all vertebrate cells. MTs are polymers of α- and β-tubulins that are each encoded by...
Cilia are microtubule (MT)-based organelles present on the surface of nearly all vertebrate cells. MTs are polymers of α- and β-tubulins that are each encoded by multiple, individual isotype genes. Tubulin isotype composition is thought to influence MT behaviors. Ciliary MTs differ from other MTs in the cell in terms of organization, stability and post-translational modifications. However, little is known about the tubulin isotypes that build ciliary MTs and the functional requirements for tubulin isotypes in cilia have not been examined in vertebrates. Here, we have tested the role of the β-tubulin isotype genes in the mouse that harbor a conserved amino acid motif associated with ciliated organisms. We found that Tubb4b localizes to cilia in multi-ciliated cells (MCCs) specifically. In respiratory and oviduct MCCs, Tubb4b is asymmetrically localized within multi-cilia, indicating that the tubulin isotype composition changes along the length of the ciliary axonemal MTs. Deletion of Tubb4b resulted in striking structural defects within the axonemes of multi-cilia, without affecting primary cilia. These studies show that Tubb4b is essential for the formation of a specific MT-based subcellular organelle and sheds light on the requirements of tubulin isotypes in cilia.
Topics: Animals; Mice; Axoneme; Cilia; Microtubules; Protein Processing, Post-Translational; Tubulin
PubMed: 38031972
DOI: 10.1242/dev.201819 -
Journal of Medical Genetics Jan 2015Primary ciliary dyskinesia (PCD) is a rare genetically heterogeneous disorder caused by the abnormal structure and/or function of motile cilia. The PCD diagnosis is... (Review)
Review
Primary ciliary dyskinesia (PCD) is a rare genetically heterogeneous disorder caused by the abnormal structure and/or function of motile cilia. The PCD diagnosis is challenging and requires a well-described clinical phenotype combined with the identification of abnormalities in ciliary ultrastructure and/or beating pattern as well as the recognition of genetic cause of the disease. Regarding the pace of identification of PCD-related genes, a rapid acceleration during the last 2-3 years is notable. This is the result of new technologies, such as whole-exome sequencing, that have been recently applied in genetic research. To date, PCD-causative mutations in 29 genes are known and the number of causative genes is bound to rise. Even though the genetic causes of approximately one-third of PCD cases still remain to be found, the current knowledge can already be used to create new, accurate genetic tests for PCD that can accelerate the correct diagnosis and reduce the proportion of unexplained cases. This review aims to present the latest data on the relations between ciliary structure aberrations and their genetic basis.
Topics: Axonemal Dyneins; Axoneme; Cilia; Genetic Testing; Humans; Kartagener Syndrome; Microscopy, Electron, Transmission
PubMed: 25351953
DOI: 10.1136/jmedgenet-2014-102755 -
The New Phytologist Aug 2012Eukaryotic cilia/flagella are ancient organelles with motility and sensory functions. Cilia display significant ultrastructural conservation where present across the... (Review)
Review
Eukaryotic cilia/flagella are ancient organelles with motility and sensory functions. Cilia display significant ultrastructural conservation where present across the eukaryotic phylogeny; however, diversity in ciliary biology exists and the ability to produce cilia has been lost independently on a number of occasions. Land plants provide an excellent system for the investigation of cilia evolution and loss across a broad phylogeny, because early divergent land plant lineages produce cilia, whereas most seed plants do not. This review highlights the differences in cilia form and function across land plants and discusses how recent advances in genomics are providing novel insights into the evolutionary trajectory of ciliary proteins. We propose a renewed effort to adopt ciliated land plants as models to investigate the mechanisms underpinning complex ciliary processes, such as number control, the coordination of basal body placement and the regulation of beat patterns.
Topics: Axoneme; Cell Membrane; Centrioles; Cilia; Embryophyta; Evolution, Molecular; Flagella; Genome, Plant; Phylogeny; Plant Cells; Plant Proteins
PubMed: 22691130
DOI: 10.1111/j.1469-8137.2012.04197.x -
PLoS Genetics Aug 2020The flagellum is essential for sperm motility and fertilization in vivo. The axoneme is the main component of the flagella, extending through its entire length. An...
The flagellum is essential for sperm motility and fertilization in vivo. The axoneme is the main component of the flagella, extending through its entire length. An axoneme is comprised of two central microtubules surrounded by nine doublets, the nexin-dynein regulatory complex, radial spokes, and dynein arms. Failure to properly assemble components of the axoneme in a sperm flagellum, leads to fertility alterations. To understand this process in detail, we have defined the function of an uncharacterized gene, Cfap97 domain containing 1 (Cfap97d1). This gene is evolutionarily conserved in mammals and multiple other species, including Chlamydomonas. We have used two independently generated Cfap97d1 knockout mouse models to study the gene function in vivo. Cfap97d1 is exclusively expressed in testes starting from post-natal day 20 and continuing throughout adulthood. Deletion of the Cfap97d1 gene in both mouse models leads to sperm motility defects (asthenozoospermia) and male subfertility. In vitro fertilization (IVF) of cumulus-intact oocytes with Cfap97d1 deficient sperm yielded few embryos whereas IVF with zona pellucida-free oocytes resulted in embryo numbers comparable to that of the control. Knockout spermatozoa showed abnormal motility characterized by frequent stalling in the anti-hook position. Uniquely, Cfap97d1 loss caused a phenotype associated with axonemal doublet heterogeneity linked with frequent loss of the fourth doublet in the sperm stored in the epididymis. This study demonstrates that Cfap97d1 is required for sperm flagellum ultra-structure maintenance, thereby playing a critical role in sperm function and male fertility in mice.
Topics: Animals; Axoneme; Chlamydomonas; Cilia; Cytoskeletal Proteins; Dyneins; Fertilization in Vitro; Humans; Infertility, Male; Male; Mice; Mice, Knockout; Sperm Motility; Sperm Tail; Spermatozoa; Testis
PubMed: 32785227
DOI: 10.1371/journal.pgen.1008954 -
Cytoskeleton (Hoboken, N.J.) Aug 2018Ciliary and flagellar motility is caused by the ensemble action of inner and outer dynein arm motors acting on axonemal doublet microtubules. The switch point or...
Ciliary and flagellar motility is caused by the ensemble action of inner and outer dynein arm motors acting on axonemal doublet microtubules. The switch point or switching hypothesis, for which much experimental and computational evidence exists, requires that dyneins on only one side of the axoneme are actively working during bending, and that this active motor region propagate along the axonemal length. Generation of a reverse bend results from switching active sliding to the opposite side of the axoneme. However, the mechanochemical states of individual dynein arms within both straight and curved regions and how these change during beating has until now eluded experimental observation. Recently, Lin and Nicastro used high-resolution cryo-electron tomography to determine the power stroke state of dyneins along flagella of sea urchin sperm that were rapidly frozen while actively beating. The results reveal that axonemal dyneins are generally in a pre-power stroke conformation that is thought to yield a force-balanced state in straight regions; inhibition of this conformational state and microtubule release on specific doublets may then lead to a force imbalance across the axoneme allowing for microtubule sliding and consequently the initiation and formation of a ciliary bend. Propagation of this inhibitory signal from base-to-tip and switching the microtubule doublet subsets that are inhibited is proposed to result in oscillatory motion.
Topics: Animals; Axonemal Dyneins; Axoneme; Cilia; Dyneins; Flagella; Male; Microtubules
PubMed: 30176122
DOI: 10.1002/cm.21483 -
Cell Death and Differentiation Jan 2018The p53 family of transcription factors (p53, p63 and p73) covers a wide range of functions critical for development, homeostasis and health of mammals across their... (Review)
Review
The p53 family of transcription factors (p53, p63 and p73) covers a wide range of functions critical for development, homeostasis and health of mammals across their lifespan. Beside the well-established tumor suppressor role, recent evidence has highlighted novel non-oncogenic functions exerted by p73. In particular, p73 is required for multiciliated cell (MCC) differentiation; MCCs have critical roles in brain and airways to move fluids across epithelial surfaces and to transport germ cells in the reproductive tract. This novel function of p73 provides a unifying cellular mechanism for the disparate inflammatory and immunological phenotypes of p73-deficient mice. Indeed, mice with Trp73 deficiency suffer from hydrocephalus, sterility and chronic respiratory tract infections due to profound defects in ciliogenesis and complete loss of mucociliary clearance since MCCs are essential for cleaning airways from inhaled pollutants, pathogens and allergens. Cross-species genomic analyses and functional rescue experiments identify TAp73 as the master transcriptional integrator of ciliogenesis, upstream of previously known central nodes. In addition, TAp73 shows a significant ability to regulate cellular metabolism and energy production through direct transcriptional regulation of several metabolic enzymes, such as glutaminase-2 and glucose-6 phosphate dehydrogenase. This recently uncovered role of TAp73 in the regulation of cellular metabolism strongly affects oxidative balance, thus potentially influencing all the biological aspects associated with p73 function, including development, homeostasis and cancer. Although through different mechanisms, p63 isoforms also contribute to regulation of cellular metabolism, thus indicating a common route used by all family members to control cell fate. At the structural level, the complexity of p73's function is further enhanced by its ability to form heterotetramers with some p63 isoforms, thus indicating the existence of an intrafamily crosstalk that determines the global outcome of p53 family function. In this review, we have tried to summarize all the recent evidence that have emerged on the novel non-oncogenic roles of p73, in an attempt to provide a unified view of the complex function of this gene within its family.
Topics: Amino Acids; Animals; Axoneme; Cilia; Epidermis; Humans; Metabolism; Mice; Oxidative Stress; Respiratory System; Transcription Factors; Transcription, Genetic; Tumor Protein p73
PubMed: 29077094
DOI: 10.1038/cdd.2017.178 -
Cytoskeleton (Hoboken, N.J.) Mar 2021Motile cilia (also interchangeably called "flagella") are conserved organelles extending from the surface of many animal cells and play essential functions in... (Review)
Review
Motile cilia (also interchangeably called "flagella") are conserved organelles extending from the surface of many animal cells and play essential functions in eukaryotes, including cell motility and environmental sensing. Large motor complexes, the ciliary dyneins, are present on ciliary outer-doublet microtubules and drive movement of cilia. Ciliary dyneins are classified into two general types: the outer dynein arms (ODAs) and the inner dynein arms (IDAs). While ODAs are important for generation of force and regulation of ciliary beat frequency, IDAs are essential for control of the size and shape of the bend, features collectively referred to as waveform. Also, recent studies have revealed unexpected links between IDA components and human diseases. In spite of their importance, studies on IDAs have been difficult since they are very complex and composed for several types of IDA motors, each unique in composition and location in the axoneme. Thanks in part to genetic, biochemical, and structural analysis of Chlamydomonas reinhardtii, we are beginning to understand the organization and function of the ciliary IDAs. In this review, we summarize the composition of Chlamydomonas IDAs particularly focusing on each subunit, and discuss the assembly, conservation, and functional role(s) of these IDA subunits. Furthermore, we raise several additional questions/challenges regarding IDAs, and discuss future perspectives of IDA studies.
Topics: Animals; Axoneme; Chlamydomonas; Chlamydomonas reinhardtii; Cilia; Dyneins; Flagella; Humans; Mutation
PubMed: 33876572
DOI: 10.1002/cm.21662 -
Proceedings of the American Thoracic... Sep 2011Because of the highly conserved nature of the ciliary axoneme, researchers studying the structure and function of cilia have used many different model systems. Each... (Review)
Review
Because of the highly conserved nature of the ciliary axoneme, researchers studying the structure and function of cilia have used many different model systems. Each system has advantages and disadvantages, but all provide important information relevant to the understanding and treatment of the ciliopathies. For example, Chlamydomonas is easy to grow and amenable to rapid genetic manipulation and therefore is excellent for motility studies and studies of the structural components of the axoneme. However, this organism cannot be used to study developmental defects or physiological abnormalities that occur in higher organisms (e.g., mucociliary clearance). Human cilia have the advantage of being obtained directly from the tissue of interest but are obtainable only in limited quantities and are difficult to manipulate. Mouse models of ciliopathies are more difficult to study than Chlamydomonas but can be useful to elucidate more aspects of the human diseases. In this review, the overlap between the structure of primary and motile cilia is discussed, and recent advancements in our understanding of cilia structure and function using these three different model systems are presented. Potential therapeutic approaches, based on fundamental knowledge gained from work in these model systems, are also presented.
Topics: Animals; Axoneme; Chlamydomonas; Cilia; Disease Models, Animal; Flagella; Heart Defects, Congenital; Heterotaxy Syndrome; Humans; Kartagener Syndrome; Mice; Models, Biological; Mutation; Proteome
PubMed: 21926393
DOI: 10.1513/pats.201103-027SD -
Cellular and Molecular Life Sciences :... Feb 2021Our understanding of motile cilia and their role in disease has increased tremendously over the last two decades, with critical information and insight coming from the... (Review)
Review
Our understanding of motile cilia and their role in disease has increased tremendously over the last two decades, with critical information and insight coming from the analysis of mouse models. Motile cilia form on specific epithelial cell types and typically beat in a coordinated, whip-like manner to facilitate the flow and clearance of fluids along the cell surface. Defects in formation and function of motile cilia result in primary ciliary dyskinesia (PCD), a genetically heterogeneous disorder with a well-characterized phenotype but no effective treatment. A number of model systems, ranging from unicellular eukaryotes to mammals, have provided information about the genetics, biochemistry, and structure of motile cilia. However, with remarkable resources available for genetic manipulation and developmental, pathological, and physiological analysis of phenotype, the mouse has risen to the forefront of understanding mammalian motile cilia and modeling PCD. This is evidenced by a large number of relevant mouse lines and an extensive body of genetic and phenotypic data. More recently, application of innovative cell biological techniques to these models has enabled substantial advancement in elucidating the molecular and cellular mechanisms underlying the biogenesis and function of mammalian motile cilia. In this article, we will review genetic and cell biological studies of motile cilia in mouse models and their contributions to our understanding of motile cilia and PCD pathogenesis.
Topics: Animals; Armadillo Domain Proteins; Axoneme; Cilia; Ciliary Motility Disorders; Disease Models, Animal; Dyneins; Mice; Microtubule-Associated Proteins; Protein Binding
PubMed: 32915243
DOI: 10.1007/s00018-020-03633-5 -
The Journal of Cell Biology Jul 2013Dynein is a microtubule-based molecular motor that is involved in various biological functions, such as axonal transport, mitosis, and cilia/flagella movement. Although... (Review)
Review
Dynein is a microtubule-based molecular motor that is involved in various biological functions, such as axonal transport, mitosis, and cilia/flagella movement. Although dynein was discovered 50 years ago, the progress of dynein research has been slow due to its large size and flexible structure. Recent progress in understanding the force-generating mechanism of dynein using x-ray crystallography, cryo-electron microscopy, and single molecule studies has provided key insight into the structure and mechanism of action of this complex motor protein.
Topics: Adenosine Triphosphate; Animals; Axoneme; Binding Sites; Biomechanical Phenomena; Chlamydomonas reinhardtii; Cilia; Dyneins; Flagella; Models, Molecular; Multiprotein Complexes; Protein Structure, Tertiary; Structure-Activity Relationship
PubMed: 23836927
DOI: 10.1083/jcb.201304099