-
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 -
Journal of Assisted Reproduction and... Feb 2016This review article provides a critical analysis of the structure and molecular mechanisms of the microtubule axoneme of cilia and sperm flagella and their associated... (Review)
Review
This review article provides a critical analysis of the structure and molecular mechanisms of the microtubule axoneme of cilia and sperm flagella and their associated elements required for male fertility.A broad range of genetic and molecular defects (ciliopathies) are considered in the context of human diseases involving impaired motility in cilia and sperm flagella, providing provocative thought for future research in the area of male infertility.
Topics: Axoneme; Cilia; Flagella; Humans; Infertility, Male; Male; Reproductive Techniques, Assisted; Spermatozoa
PubMed: 26825807
DOI: 10.1007/s10815-016-0652-1 -
Acta Crystallographica. Section D,... Apr 2024The axoneme, a microtubule-based array at the center of every cilium, has been the subject of structural investigations for decades, but only recent advances in cryo-EM... (Review)
Review
The axoneme, a microtubule-based array at the center of every cilium, has been the subject of structural investigations for decades, but only recent advances in cryo-EM and cryo-ET have allowed a molecular-level interpretation of the entire complex to be achieved. The unique properties of the nine doublet microtubules and central pair of singlet microtubules that form the axoneme, including the highly decorated tubulin lattice and the docking of massive axonemal complexes, provide opportunities and challenges for sample preparation, 3D reconstruction and atomic modeling. Here, the approaches used for cryo-EM and cryo-ET of axonemes are reviewed, while highlighting the unique opportunities provided by the latest generation of AI-guided tools that are transforming structural biology.
Topics: Axoneme; Cilia; Microtubules; Molecular Biology
PubMed: 38451206
DOI: 10.1107/S2059798324001815 -
Molecular Biology of the Cell Jul 2022The centriole is a minute cylindrical organelle present in a wide range of eukaryotic species. Most centrioles have a signature ninefold radial symmetry of microtubules...
The centriole is a minute cylindrical organelle present in a wide range of eukaryotic species. Most centrioles have a signature ninefold radial symmetry of microtubules that is imparted to the axonemes of the cilia and flagella they template, with nine centriolar microtubule doublets growing into nine axonemal microtubule doublets. There are exceptions to the ninefold symmetrical arrangement of axonemal microtubules in some species, with lower or higher fold symmetries. In the few cases where this has been examined, such alterations in axonemal symmetries are grounded in similar alterations in centriolar symmetries. Here, we examine the question of microtubule number continuity between centriole and axoneme in flagellated gametes of the gregarine , which have been reported to exhibit a sixfold radial symmetry of axonemal microtubules. We used time-lapse differential interference microscopy to identify the stage at which flagellated gametes are present. Thereafter, using electron microscopy and ultrastructure-expansion microscopy coupled to stimulated emission depletion superresolution imaging, we uncover that a six- or fivefold radial symmetry in the axoneme is accompanied by an eightfold radial symmetry in the centriole. We conclude that the transition between centriolar and axonemal microtubules can be characterized by unexpected plasticity.
Topics: Apicomplexa; Axoneme; Centrioles; Cilia; Flagella; Microtubules
PubMed: 35544302
DOI: 10.1091/mbc.E22-04-0123 -
Molecular Biology of the Cell Jun 2023Microtubules are noncovalent polymers built from αβ-tubulin dimers. The disordered C-terminal tubulin tails are functionalized with multiple glutamate chains of...
Microtubules are noncovalent polymers built from αβ-tubulin dimers. The disordered C-terminal tubulin tails are functionalized with multiple glutamate chains of variable lengths added and removed by tubulin tyrosine ligases (TTLLs) and carboxypeptidases (CCPs). Glutamylation is abundant on stable microtubule arrays such as in axonemes and axons, and its dysregulation leads to human pathologies. Despite this, the effects of glutamylation on intrinsic microtubule dynamics are unclear. Here we generate tubulin with short and long glutamate chains and show that glutamylation slows the rate of microtubule growth and increases catastrophes as a function of glutamylation levels. This implies that the higher stability of glutamylated microtubules in cells is due to effectors. Interestingly, EB1 is minimally affected by glutamylation and thus can report on the growth rates of both unmodified and glutamylated microtubules. Finally, we show that glutamate removal by CCP1 and 5 is synergistic and occurs preferentially on soluble tubulin, unlike TTLL enzymes that prefer microtubules. This substrate preference establishes an asymmetry whereby once the microtubule depolymerizes, the released tubulin is reset to a less-modified state, while polymerized tubulin accumulates the glutamylation mark. Our work shows that a modification on the disordered tubulin tails can directly affect microtubule dynamics and furthers our understanding of the mechanistic underpinnings of the tubulin code.
Topics: Humans; Tubulin; Microtubules; Glutamic Acid; Axoneme; Protein Processing, Post-Translational
PubMed: 37074962
DOI: 10.1091/mbc.E23-01-0030 -
Nature Communications Sep 2023Cilia are hairlike protrusions that project from the surface of eukaryotic cells and play key roles in cell signaling and motility. Ciliary motility is regulated by the...
Cilia are hairlike protrusions that project from the surface of eukaryotic cells and play key roles in cell signaling and motility. Ciliary motility is regulated by the conserved nexin-dynein regulatory complex (N-DRC), which links adjacent doublet microtubules and regulates and coordinates the activity of outer doublet complexes. Despite its critical role in cilia motility, the assembly and molecular basis of the regulatory mechanism are poorly understood. Here, using cryo-electron microscopy in conjunction with biochemical cross-linking and integrative modeling, we localize 12 DRC subunits in the N-DRC structure of Tetrahymena thermophila. We also find that the CCDC96/113 complex is in close contact with the DRC9/10 in the linker region. In addition, we reveal that the N-DRC is associated with a network of coiled-coil proteins that most likely mediates N-DRC regulatory activity.
Topics: Dyneins; Cryoelectron Microscopy; Microtubule-Associated Proteins; Cytoskeleton; Axoneme; Amyloidogenic Proteins
PubMed: 37714832
DOI: 10.1038/s41467-023-41480-7 -
Nature Communications Jan 2021Axonemal dyneins are tethered to doublet microtubules inside cilia to drive ciliary beating, a process critical for cellular motility and extracellular fluid flow....
Axonemal dyneins are tethered to doublet microtubules inside cilia to drive ciliary beating, a process critical for cellular motility and extracellular fluid flow. Axonemal dyneins are evolutionarily and biochemically distinct from cytoplasmic dyneins that transport cargo, and the mechanisms regulating their localization and function are poorly understood. Here, we report a single-particle cryo-EM reconstruction of a three-headed axonemal dynein natively bound to doublet microtubules isolated from cilia. The slanted conformation of the axonemal dynein causes interaction of its motor domains with the neighboring dynein complex. Our structure shows how a heterotrimeric docking complex specifically localizes the linear array of axonemal dyneins to the doublet microtubule by directly interacting with the heavy chains. Our structural analysis establishes the arrangement of conserved heavy, intermediate and light chain subunits, and provides a framework to understand the roles of individual subunits and the interactions between dyneins during ciliary waveform generation.
Topics: Axonemal Dyneins; Cell Movement; Chlamydomonas reinhardtii; Cilia; Cryoelectron Microscopy; Cytoskeleton; Flagella; Microtubules; Molecular Docking Simulation
PubMed: 33473120
DOI: 10.1038/s41467-020-20735-7 -
Nature Structural & Molecular Biology Mar 2023The flagella of mammalian sperm display non-planar, asymmetric beating, in contrast to the planar, symmetric beating of flagella from sea urchin sperm and unicellular...
The flagella of mammalian sperm display non-planar, asymmetric beating, in contrast to the planar, symmetric beating of flagella from sea urchin sperm and unicellular organisms. The molecular basis of this difference is unclear. Here, we perform in situ cryo-electron tomography of mouse and human sperm, providing the highest-resolution structural information to date. Our subtomogram averages reveal mammalian sperm-specific protein complexes within the microtubules, the radial spokes and nexin-dynein regulatory complexes. The locations and structures of these complexes suggest potential roles in enhancing the mechanical strength of mammalian sperm axonemes and regulating dynein-based axonemal bending. Intriguingly, we find that each of the nine outer microtubule doublets is decorated with a distinct combination of sperm-specific complexes. We propose that this asymmetric distribution of proteins differentially regulates the sliding of each microtubule doublet and may underlie the asymmetric beating of mammalian sperm.
Topics: Animals; Male; Humans; Axoneme; Dyneins; Electron Microscope Tomography; Semen; Spermatozoa; Microtubules; Flagella; Mammals
PubMed: 36593309
DOI: 10.1038/s41594-022-00861-0 -
Paediatric Respiratory Reviews Mar 2016Ciliopathies are a growing class of disorders caused by abnormal ciliary axonemal structure and function. Our understanding of the complex genetic and functional... (Review)
Review
Ciliopathies are a growing class of disorders caused by abnormal ciliary axonemal structure and function. Our understanding of the complex genetic and functional phenotypes of these conditions has rapidly progressed. Primary ciliary dyskinesia (PCD) remains the sole genetic disorder of motile cilia dysfunction. However, unlike many Mendelian genetic disorders, PCD is not caused by mutations in a single gene or locus, but rather, autosomal recessive mutation in one of many genes that lead to a similar phenotype. The first reported PCD mutations, more than a decade ago, identified genes encoding known structural components of the ciliary axoneme. In recent years, mutations in genes encoding novel cytoplasmic and regulatory proteins have been discovered. These findings have provided new insights into the functions of the motile cilia, and a better understanding of motile cilia disease. Advances in genetic tools will soon allow more precise genetic testing, mandating that clinicians must understand the genetic basis of PCD. Here, we review genetic mutations, their biological impact on cilia structure and function, and the implication of emerging genetic diagnostic tools.
Topics: Animals; Genetic Markers; Genetic Predisposition to Disease; Genetic Testing; Humans; Kartagener Syndrome; Mutation; Phenotype
PubMed: 26476603
DOI: 10.1016/j.prrv.2015.09.001 -
PloS One 2020Aberrant methylation of DNA plays an important role in the pathogenesis of nasopharyngeal carcinoma (NPC). In the current study, we aimed to integrate three cohorts...
BACKGROUND
Aberrant methylation of DNA plays an important role in the pathogenesis of nasopharyngeal carcinoma (NPC). In the current study, we aimed to integrate three cohorts profile datasets to identify abnormally methylated-differentially expressed genes and pathways associated with NPC.
METHODS
Data of gene expression microarrays (GSE53819, GSE412452) and gene methylation microarrays (GSE52068) obtained from the GEO database. Aberrantly methylated differentially expressed genes (DEGs) were obtained by GEO2R. The David database was utilized to perform enrichment and functional analysis regarding selected genes. To create a protein-protein interaction (PPI), STRING and Cytoscape software were utilized. The MCODE was used for module analysis of the PPI network.
RESULTS
In total, 181 hypomethylation-high expression genes were identified, which were enriched in the biological mechanisms involved in the differentiation of endodermal cell, mitotic nuclear division, mitotic cell cycle process, chromosome segregation and cell cycle phase transition, etc. Pathway enrichment showed ECM-receptor interaction, PI3K-Akt signaling pathway, Focal adhesion, Protein digestion and absorption and Amoebiasis, etc. The top 3 hub genes of PPI network were FANCI, POSTN, and IFIH1. Additionally, 210 hypermethylation-low expression genes were identified, and our data revealed enrichment in biological processes including axoneme assembly, micro tubular formation, assembly of axonemal dynein complex, cilium movement and cilium organization, etc. Pathway analysis indicated enrichment in B cell receptor signaling pathway, Hematopoietic cell lineage, Leukocyte transendothelial migration, Complement and coagulation cascades and Fc gamma R-mediated phagocytosis, etc. The ZMYND10, PACRG and POU2AF1 were identified as the top three hub genes of PPI network. After validation in TCGA and GEPIA database, most hub genes remained significant. Patients with high expression of POSTN found to have shorter overall survival, while in patients with high expression of ZMYND10 and POU2AF1 longer overall survival was identified.
CONCLUSIONS
The data revealed novel aberrantly methylated-differentially expressed genes and pathways in NPC by bioinformatics analysis, potentially providing novel insights for the molecular mechanisms governing NPC progression. Hub genes including FANCI, POSTN, IFIH1, ZMYND10, PACRG and POU2AF1 might serve as novel biomarkers for precision diagnosis and providing medical treatment for patient with NPC.
Topics: Biomarkers, Tumor; Case-Control Studies; DNA Methylation; Disease Progression; Epigenesis, Genetic; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Gene Regulatory Networks; Genetic Markers; Humans; Microarray Analysis; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Neoplasm Staging; Prognosis; Protein Interaction Mapping; Protein Interaction Maps; Signal Transduction; Transcriptome
PubMed: 32271791
DOI: 10.1371/journal.pone.0230524