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Current Biology : CB Sep 2010Centrioles are conserved microtubule-based organelles that lie at the core of the animal centrosome and play a crucial role in nucleating the formation of cilia and... (Review)
Review
Centrioles are conserved microtubule-based organelles that lie at the core of the animal centrosome and play a crucial role in nucleating the formation of cilia and flagella in most eukaryotes. Centrioles have a complex ultrastructure with ninefold symmetry and a well-defined length. This structure is assembled from a host of proteins, including a variety of disease gene products. Over a century after the discovery of centrioles, the mechanisms underlying the assembly of these fascinating organelles, in particular the establishment of ninefold symmetry and the control of centriole length, are now starting to be uncovered.
Topics: Animals; Axoneme; Centrioles; Cilia; Flagella; Humans; Microtubules; Models, Biological; Phylogeny
PubMed: 20869612
DOI: 10.1016/j.cub.2010.08.010 -
Jornal Brasileiro de Pneumologia :... 2015Primary ciliary dyskinesia (PCD) is a genetic disorder of ciliary structure or function. It results in mucus accumulation and bacterial colonization of the respiratory... (Review)
Review
Primary ciliary dyskinesia (PCD) is a genetic disorder of ciliary structure or function. It results in mucus accumulation and bacterial colonization of the respiratory tract which leads to chronic upper and lower airway infections, organ laterality defects, and fertility problems. We review the respiratory signs and symptoms of PCD, as well as the screening tests for and diagnostic investigation of the disease, together with details related to ciliary function, ciliary ultrastructure, and genetic studies. In addition, we describe the difficulties in diagnosing PCD by means of transmission electron microscopy, as well as describing patient follow-up procedures.
Topics: Axoneme; Cilia; Dyneins; Genetic Diseases, Inborn; Humans; Kartagener Syndrome; Microscopy, Electron; Tomography, X-Ray Computed
PubMed: 26176524
DOI: 10.1590/S1806-37132015000004447 -
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 -
EMBO Reports Jan 2024The primary cilium is a critical sensory organelle that is built of axonemal microtubules ensheathed by a ciliary membrane. In polarized epithelial cells, primary cilia...
The primary cilium is a critical sensory organelle that is built of axonemal microtubules ensheathed by a ciliary membrane. In polarized epithelial cells, primary cilia reside on the apical surface and must extend these microtubules directly into the extracellular space and remain a stable structure. However, the factors regulating cross-talk between ciliation and cell polarization, as well as axonemal microtubule growth and stabilization in polarized epithelia, are not fully understood. In this study, we find TTLL12, a previously uncharacterized member of the Tubulin Tyrosine Ligase-Like (TTLL) family, localizes to the base of primary cilia and is required for cilia formation in polarized renal epithelial cells. We also show that TTLL12 directly binds to the α/β-tubulin heterodimer in vitro and regulates microtubule dynamics, stability, and post-translational modifications (PTMs). While all other TTLLs catalyze the addition of glutamate or glycine to microtubule C-terminal tails, TTLL12 uniquely affects tubulin PTMs by promoting both microtubule lysine acetylation and arginine methylation. Together, this work identifies a novel microtubule regulator and provides insight into the requirements for apical extracellular axoneme formation.
Topics: Cilia; Tubulin; Axoneme; Microtubules; Epithelial Cells
PubMed: 38177908
DOI: 10.1038/s44319-023-00005-5 -
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 -
American Journal of Human Genetics Sep 2020Multiple morphological abnormalities of the sperm flagella (MMAF) is a severe form of asthenoteratozoospermia. Although recent studies have revealed several...
Multiple morphological abnormalities of the sperm flagella (MMAF) is a severe form of asthenoteratozoospermia. Although recent studies have revealed several MMAF-associated genes and demonstrated MMAF to be a genetically heterogeneous disease, at least one-third of the cases are still not well understood for their etiology. Here, we identified bi-allelic loss-of-function variants in CFAP58 by using whole-exome sequencing in five (5.6%) unrelated individuals from a cohort of 90 MMAF-affected Chinese men. Each of the men harboring bi-allelic CFAP58 variants presented typical MMAF phenotypes. Transmission electron microscopy demonstrated striking flagellar defects with axonemal and mitochondrial sheath malformations. CFAP58 is predominantly expressed in the testis and encodes a cilia- and flagella-associated protein. Immunofluorescence assays showed that CFAP58 localized at the entire flagella of control sperm and predominantly concentrated in the mid-piece. Immunoblotting and immunofluorescence assays showed that the abundances of axoneme ultrastructure markers SPAG6 and SPEF2 and a mitochondrial sheath protein, HSP60, were significantly reduced in the spermatozoa from men harboring bi-allelic CFAP58 variants. We generated Cfap58-knockout mice via CRISPR/Cas9 technology. The male mice were infertile and presented with severe flagellar defects, consistent with the sperm phenotypes in MMAF-affected men. Overall, our findings in humans and mice strongly suggest that CFAP58 plays a vital role in sperm flagellogenesis and demonstrate that bi-allelic loss-of-function variants in CFAP58 can cause axoneme and peri-axoneme malformations leading to male infertility. This study provides crucial insights for understanding and counseling of MMAF-associated asthenoteratozoospermia.
Topics: Abnormalities, Multiple; Alleles; Animals; Asthenozoospermia; Axoneme; CRISPR-Cas Systems; Cell Cycle Proteins; Homozygote; Humans; Infertility, Male; Intercellular Signaling Peptides and Proteins; Loss of Function Mutation; Loss of Heterozygosity; Male; Mice; Mice, Knockout; Microtubule Proteins; Mitochondria; Sperm Tail; Testis; Exome Sequencing
PubMed: 32791035
DOI: 10.1016/j.ajhg.2020.07.010 -
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 -
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.) Feb 2021The mechanism that allows the axoneme of eukaryotic cilia and flagella to produce both helical and planar beating is an enduring puzzle. The nine outer doublets of... (Review)
Review
The mechanism that allows the axoneme of eukaryotic cilia and flagella to produce both helical and planar beating is an enduring puzzle. The nine outer doublets of eukaryotic cilia and flagella are arranged in a circle. Therefore, each doublet pair with its associated dynein motors, should produce torque to bend the flagellum in a different direction. Sequential activation of each doublet pair should, therefore result in a helical bending wave. In reality, most cilia and flagella have a well-defined bending plane and many exhibit an almost perfectly flat (planar) beating pattern. In this analysis we examine the physics that governs flagellar bending, and arrive at two distinct possibilities that could explain the mechanism of planar beating. Of these, the mechanism with the best observational support is that the flagellum behaves as two ribbons of doublets interacting with a central partition. We also examine the physics of torsion in flagella and conclude that torsion could play a role in transitioning from a planar to a helical beating modality in long flagella. Lastly, we suggest some tests that would provide theoretical and/or experimental evaluation of our proposals.
Topics: Axoneme; Cilia; Cytoskeleton; Dyneins; Flagella
PubMed: 33675288
DOI: 10.1002/cm.21656 -
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