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Cellular & Molecular Biology Letters May 2024By analyzing a mouse Interspecific Recombinant Congenic Strain (IRCS), we previously identified a quantitative trait locus (QTL), called Mafq1 on mouse chromosome 1,...
By analyzing a mouse Interspecific Recombinant Congenic Strain (IRCS), we previously identified a quantitative trait locus (QTL), called Mafq1 on mouse chromosome 1, that is associated with male hypofertility and ultrastructural sperm abnormalities. Within this locus, we identified a new candidate gene that could be implicated in a reproductive phenotype: Tex44 (Testis-expressed protein 44). We thus performed a CRISPR/Cas9-mediated complete deletion of this gene in mice in order to study its function. Tex44-KO males were severely hypofertile in vivo and in vitro due to a drastic reduction of sperm motility which itself resulted from important morphological sperm abnormalities. Namely, Tex44-KO sperm showed a disorganized junction between the midpiece and the principal piece of the flagellum, leading to a 180° flagellar bending in this region. In addition, the loss of some axonemal microtubule doublets and outer dense fibers in the flagellum's principal piece has been observed. Our results suggest that, in mice, TEX44 is implicated in the correct set-up of the sperm flagellum during spermiogenesis and its absence leads to flagellar abnormalities and consequently to severe male hypofertility.
Topics: Animals; Male; Infertility, Male; Sperm Motility; Sperm Tail; Mice; Mice, Knockout; Spermatozoa; Spermatogenesis; Flagella; Mice, Inbred C57BL; CRISPR-Cas Systems
PubMed: 38750428
DOI: 10.1186/s11658-024-00587-5 -
BMC Genomics May 2024The severity of COVID-19 is influenced by various factors including the presence of respiratory diseases. Studies have indicated a potential relationship between asthma...
BACKGROUND
The severity of COVID-19 is influenced by various factors including the presence of respiratory diseases. Studies have indicated a potential relationship between asthma and COVID-19 severity.
OBJECTIVE
This study aimed to conduct a genome-wide association study (GWAS) to identify genetic and clinical variants associated with the severity of COVID-19, both among patients with and without asthma.
METHODS
We analyzed data from 2131 samples sourced from the Biobanque québécoise de la COVID-19 (BQC19), with 1499 samples from patients who tested positive for COVID-19. Among these, 1110 exhibited mild-to-moderate symptoms, 389 had severe symptoms, and 58 had asthma. We conducted a comparative analysis of clinical data from individuals in these three groups and GWAS using a logistic regression model. Phenotypic data analysis resulted in the refined covariates integrated into logistic models for genetic studies.
RESULTS
Considering a significance threshold of 1 × 10, seven genetic variants were associated with severe COVID-19. These variants were located proximal to five genes: sodium voltage-gated channel alpha subunit 1 (SCN10A), desmoplakin (DSP), RP1 axonemal microtubule associated (RP1), IGF like family member 1 (IGFL1), and docking protein 5 (DOK5). The GWAS comparing individuals with severe COVID-19 with asthma to those without asthma revealed four genetic variants in transmembrane protein with EGF like and two follistatin like domains 2 (TMEFF2) and huntingtin interacting protein-1 (HIP1) genes.
CONCLUSION
This study provides significant insights into the genetic profiles of patients with severe forms of the disease, whether accompanied by asthma or not. These findings enhance our comprehension of the genetic factors that affect COVID-19 severity.
KEY MESSAGES
Seven genetic variants were associated with the severe form of COVID-19; Four genetic variants were associated with the severe form of COVID-19 in individuals with comorbid asthma; These findings help define the genetic component of the severe form of COVID-19 in relation to asthma as a comorbidity.
Topics: Humans; COVID-19; Asthma; Genome-Wide Association Study; Male; Female; Middle Aged; SARS-CoV-2; Comorbidity; Adult; Severity of Illness Index; Cohort Studies; Polymorphism, Single Nucleotide; Aged; Genomics; Genetic Predisposition to Disease
PubMed: 38750426
DOI: 10.1186/s12864-024-10342-x -
Current Biology : CB Jun 2024A primary cilium is a membrane-bound extension from the cell surface that contains receptors for perceiving and transmitting signals that modulate cell state and...
A primary cilium is a membrane-bound extension from the cell surface that contains receptors for perceiving and transmitting signals that modulate cell state and activity. Primary cilia in the brain are less accessible than cilia on cultured cells or epithelial tissues because in the brain they protrude into a deep, dense network of glial and neuronal processes. Here, we investigated cilia frequency, internal structure, shape, and position in large, high-resolution transmission electron microscopy volumes of mouse primary visual cortex. Cilia extended from the cell bodies of nearly all excitatory and inhibitory neurons, astrocytes, and oligodendrocyte precursor cells (OPCs) but were absent from oligodendrocytes and microglia. Ultrastructural comparisons revealed that the base of the cilium and the microtubule organization differed between neurons and glia. Investigating cilia-proximal features revealed that many cilia were directly adjacent to synapses, suggesting that cilia are poised to encounter locally released signaling molecules. Our analysis indicated that synapse proximity is likely due to random encounters in the neuropil, with no evidence that cilia modulate synapse activity as would be expected in tetrapartite synapses. The observed cell class differences in proximity to synapses were largely due to differences in external cilia length. Many key structural features that differed between neuronal and glial cilia influenced both cilium placement and shape and, thus, exposure to processes and synapses outside the cilium. Together, the ultrastructure both within and around neuronal and glial cilia suggest differences in cilia formation and function across cell types in the brain.
Topics: Animals; Cilia; Mice; Microscopy, Electron, Transmission; Mice, Inbred C57BL; Neurons; Visual Cortex; Neuroglia; Female; Synapses; Male
PubMed: 38749425
DOI: 10.1016/j.cub.2024.04.043 -
Science (New York, N.Y.) May 2024
PubMed: 38723101
DOI: 10.1126/science.adq2178 -
Genesis (New York, N.Y. : 2000) Jun 2024Cilia play a key role in the regulation of signaling pathways required for embryonic development, including the proper formation of the neural tube, the precursor to the...
Cilia play a key role in the regulation of signaling pathways required for embryonic development, including the proper formation of the neural tube, the precursor to the brain and spinal cord. Forward genetic screens were used to generate mouse lines that display neural tube defects (NTD) and secondary phenotypes useful in interrogating function. We describe here the L3P mutant line that displays phenotypes of disrupted Sonic hedgehog signaling and affects the initiation of cilia formation. A point mutation was mapped in the L3P line to the gene Rsg1, which encodes a GTPase-like protein. The mutation lies within the GTP-binding pocket and disrupts the highly conserved G1 domain. The mutant protein and other centrosomal and IFT proteins still localize appropriately to the basal body of cilia, suggesting that RSG1 GTPase activity is not required for basal body maturation but is needed for a downstream step in axonemal elongation.
Topics: Animals; Mice; Cilia; Hedgehog Proteins; Neural Tube; Neural Tube Defects; Point Mutation; Signal Transduction
PubMed: 38721990
DOI: 10.1002/dvg.23602 -
BioRxiv : the Preprint Server For... Apr 2024Proper connection between the sperm head and tail is critical for sperm motility and fertilization. The link between the head and tail is mediated by the Head-Tail...
Proper connection between the sperm head and tail is critical for sperm motility and fertilization. The link between the head and tail is mediated by the Head-Tail Coupling Apparatus (HTCA), which secures the axoneme (tail) to the nucleus (head). However, the molecular architecture of the HTCA is not well understood. Here, we use to create a high-resolution map of proteins and structures at the HTCA throughout spermiogenesis. Using structured illumination microscopy, we demonstrate that key HTCA proteins Spag4 and Yuri form a 'Centriole Cap' that surrounds the centriole (or Basal Body) as it is inserted, or embedded into the surface of the nucleus. As development progresses, the centriole is laterally displaces to the side of the nucleus, during which time the HTCA expands under the nucleus, forming what we term the 'Nuclear Shelf.' We next show that the proximal centriole-like (PCL) structure is positioned under the Nuclear Shelf and functions as a critical stabilizer of the centriole-nuclear attachment. Together, our data indicate that the HTCA is complex, multi-point attachment site that simultaneously engages the PCL, the centriole, and the nucleus to ensure proper head-tail connection during late-stage spermiogenesis.
PubMed: 38712096
DOI: 10.1101/2024.04.15.589606 -
Molecular Biology of the Cell Jul 2024Cilia are highly complex motile, sensory, and secretory organelles that contain perhaps 1000 or more distinct protein components, many of which are subject to various...
Cilia are highly complex motile, sensory, and secretory organelles that contain perhaps 1000 or more distinct protein components, many of which are subject to various posttranslational modifications such as phosphorylation, N-terminal acetylation, and proteolytic processing. Another common modification is the addition of one or more methyl groups to the side chains of arginine and lysine residues. These tunable additions delocalize the side-chain charge, decrease hydrogen bond capacity, and increase both bulk and hydrophobicity. Methylation is usually mediated by S-adenosylmethionine (SAM)-dependent methyltransferases and reversed by demethylases. Previous studies have identified several ciliary proteins that are subject to methylation including axonemal dynein heavy chains that are modified by a cytosolic methyltransferase. Here, we have performed an extensive proteomic analysis of multiple independently derived cilia samples to assess the potential for SAM metabolism and the extent of methylation in these organelles. We find that cilia contain all the enzymes needed for generation of the SAM methyl donor and recycling of the S-adenosylhomocysteine and tetrahydrofolate byproducts. In addition, we find that at least 155 distinct ciliary proteins are methylated, in some cases at multiple sites. These data provide a comprehensive resource for studying the consequences of methyl marks on ciliary biology.
Topics: Cilia; S-Adenosylmethionine; Methylation; Protein Processing, Post-Translational; Proteomics; Animals; Humans; Methyltransferases; S-Adenosylhomocysteine; Epigenome
PubMed: 38696262
DOI: 10.1091/mbc.E24-03-0130 -
Nihon Yakurigaku Zasshi. Folia... Jul 2024A photoreceptor is a specialized neuron that is responsible for the conversion of light into an electrical signal. Photoreceptors are classified into rods and cones, and... (Review)
Review
A photoreceptor is a specialized neuron that is responsible for the conversion of light into an electrical signal. Photoreceptors are classified into rods and cones, and both photoreceptors possess light-sensing ciliary organelles called outer segments (OSs), anchored in the cells by a microtubule-based axoneme. The OS consists of a stack of disc membranes, which are abundant for the retinal phototransduction proteins such as rhodopsin. Recently, modern protein synchronization techniques using in vivo transfection in rodents revealed that rhodopsin transits through Rab11-positive recycling endosomes, preferentially entering the OS in the dark. Moreover, Peripherin-2 (PRPH2, also called retinal degeneration slow, RDS), a photoreceptor-specific tetraspanin protein essential for the morphogenesis of disc membranes, is delivered to the OS following complementary to that of rhodopsin. Various PRPH2 disease-causing mutations have been found in humans, and most of the mutations in the cytosolic C-terminus of PRPH2 are linked to cone-dominant macular dystrophies. It has been shown that the late endosome is the waystation that sorts newly synthesized PRPH2 into the cilium. The multiple C-terminal motifs of PRPH2 regulate its late endosome and ciliary targeting through ubiquitination and binding to an Endosomal Sorting Complexes Required for Transport (ESCRT) component, Hrs. These findings suggest that the late endosomes play an important role in the biosynthetic pathway of ciliary proteins and can be a new therapeutic target for the diseases caused by ciliary defects.
Topics: Endosomes; Animals; Cilia; Humans; Peripherins; Cell Membrane; Protein Transport
PubMed: 38684400
DOI: 10.1254/fpj.23077 -
Advanced Science (Weinheim,... Apr 2024The photoreceptor cilium is vital for maintaining the structure and function of the retina. However, the molecular mechanisms underlying the photoreceptor cilium...
The photoreceptor cilium is vital for maintaining the structure and function of the retina. However, the molecular mechanisms underlying the photoreceptor cilium integrity and retinal homeostasis are largely unknown. Herein, it is shown that kinesin family member 11 (KIF11) localizes at the transition zone (connecting cilium) of the photoreceptor and plays a crucial role in orchestrating the cilium integrity. KIF11 depletion causes malformations of both the photoreceptor ciliary axoneme and membranous discs, resulting in photoreceptor degeneration and the accumulation of drusen-like deposits throughout the retina. Mechanistic studies show that the stability of KIF11 is regulated by an interplay between its UFMylation and ubiquitination; UFMylation of KIF11 at lysine 953 inhibits its ubiquitination by synoviolin 1 and thereby prevents its proteasomal degradation. The lysine 953-to-arginine mutant of KIF11 is more stable than wild-type KIF11 and also more effective in reversing the ciliary and retinal defects induced by KIF11 depletion. These findings identify a critical role for KIF11 UFMylation in the maintenance of photoreceptor cilium integrity and retinal homeostasis.
PubMed: 38666385
DOI: 10.1002/advs.202400569 -
Ciliopathy patient variants reveal organelle-specific functions for TUBB4B in axonemal microtubules.Science (New York, N.Y.) Apr 2024Tubulin, one of the most abundant cytoskeletal building blocks, has numerous isotypes in metazoans encoded by different conserved genes. Whether these distinct isotypes...
Tubulin, one of the most abundant cytoskeletal building blocks, has numerous isotypes in metazoans encoded by different conserved genes. Whether these distinct isotypes form cell type- and context-specific microtubule structures is poorly understood. Based on a cohort of 12 patients with primary ciliary dyskinesia as well as mouse mutants, we identified and characterized variants in the isotype that specifically perturbed centriole and cilium biogenesis. Distinct variants differentially affected microtubule dynamics and cilia formation in a dominant-negative manner. Structure-function studies revealed that different TUBB4B variants disrupted distinct tubulin interfaces, thereby enabling stratification of patients into three classes of ciliopathic diseases. These findings show that specific tubulin isotypes have distinct and nonredundant subcellular functions and establish a link between tubulinopathies and ciliopathies.
Topics: Animals; Humans; Mice; Axoneme; Centrioles; Cilia; Ciliary Motility Disorders; Mutation; Protein Isoforms; Tubulin; Male; Female; Mice, Knockout
PubMed: 38662826
DOI: 10.1126/science.adf5489