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Genetics Jun 2024In humans, MAPK8IP3 (also known as JIP3) is a neurodevelopmental disorder-associated gene. In Caenorhabditis elegans, the UNC-16 ortholog of the MAPK8IP3 protein can...
In humans, MAPK8IP3 (also known as JIP3) is a neurodevelopmental disorder-associated gene. In Caenorhabditis elegans, the UNC-16 ortholog of the MAPK8IP3 protein can regulate the termination of axon growth. However, its role in this process is not well understood. Here, we report that UNC-16 promotes axon termination through a process that includes the LRK-1 (LRRK-1/LRRK-2) kinase and the WDFY-3 (WDFY3/Alfy) selective autophagy protein. Genetic analysis suggests that UNC-16 promotes axon termination through an interaction between its RH1 domain and the dynein complex. Loss of unc-16 function causes accumulation of late endosomes specifically in the distal axon. Moreover, we observe synergistic interactions between loss of unc-16 function and disruptors of endolysosomal function, indicating that the endolysosomal system promotes axon termination. We also find that the axon termination defects caused by loss of UNC-16 function require the function of a genetic pathway that includes lrk-1 and wdfy-3, 2 genes that have been implicated in autophagy. These observations suggest a model where UNC-16 promotes axon termination by interacting with the endolysosomal system to regulate a pathway that includes LRK-1 and WDFY-3.
Topics: Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Axons; Endosomes; Autophagy; Dyneins; Nerve Tissue Proteins; Protein Serine-Threonine Kinases; Adaptor Proteins, Signal Transducing
PubMed: 38581414
DOI: 10.1093/genetics/iyae053 -
Molecular Biology of the Cell May 2024Cilia generate three-dimensional waveforms required for cell motility and transport of fluid, mucus, and particles over the cell surface. This movement is driven by...
Cilia generate three-dimensional waveforms required for cell motility and transport of fluid, mucus, and particles over the cell surface. This movement is driven by multiple dynein motors attached to nine outer doublet microtubules that form the axoneme. The outer and inner arm dyneins are organized into 96-nm repeats tandemly arrayed along the length of the doublets. Motility is regulated in part by projections from the two central pair microtubules that contact radial spokes located near the base of the inner dynein arms in each repeat. Although much is known about the structures and protein complexes within the axoneme, many questions remain about the regulatory mechanisms that allow the cilia to modify their waveforms in response to internal or external stimuli. Here, we used (ove ackwards nly) mutants with altered waveforms to identify at least two conserved proteins, MBO2/CCDC146 and FAP58/CCDC147, that form part of a L-shaped structure that varies between doublet microtubules. Comparative proteomics identified additional missing proteins that are altered in other motility mutants, revealing overlapping protein defects. Cryo-electron tomography and epitope tagging revealed that the L-shaped, MBO2/FAP58 structure interconnects inner dynein arms with multiple regulatory complexes, consistent with its function in modifying the ciliary waveform.
Topics: Axoneme; Dyneins; Microtubules; Cilia; Proteins; Flagella
PubMed: 38568782
DOI: 10.1091/mbc.E23-11-0439 -
Experimental & Molecular Medicine Apr 2024Intracellular retrograde transport in eukaryotic cells relies exclusively on the molecular motor cytoplasmic dynein 1. Unlike its counterpart, kinesin, dynein has a... (Review)
Review
Intracellular retrograde transport in eukaryotic cells relies exclusively on the molecular motor cytoplasmic dynein 1. Unlike its counterpart, kinesin, dynein has a single isoform, which raises questions about its cargo specificity and regulatory mechanisms. The precision of dynein-mediated cargo transport is governed by a multitude of factors, including temperature, phosphorylation, the microtubule track, and interactions with a family of activating adaptor proteins. Activating adaptors are of particular importance because they not only activate the unidirectional motility of the motor but also connect a diverse array of cargoes with the dynein motor. Therefore, it is unsurprising that dysregulation of the dynein-activating adaptor transport machinery can lead to diseases such as spinal muscular atrophy, lower extremity, and dominant. Here, we discuss dynein motor motility within cells and in in vitro, and we present several methodologies employed to track the motion of the motor. We highlight several newly identified activating adaptors and their roles in regulating dynein. Finally, we explore the potential therapeutic applications of manipulating dynein transport to address diseases linked to dynein malfunction.
Topics: Humans; Cytoplasmic Dyneins; Animals; Biological Transport; Microtubules; Dyneins
PubMed: 38556551
DOI: 10.1038/s12276-024-01200-7 -
Science (New York, N.Y.) Mar 2024Cytoplasmic dynein is a microtubule motor vital for cellular organization and division. It functions as a ~4-megadalton complex containing its cofactor dynactin and a...
Cytoplasmic dynein is a microtubule motor vital for cellular organization and division. It functions as a ~4-megadalton complex containing its cofactor dynactin and a cargo-specific coiled-coil adaptor. However, how dynein and dynactin recognize diverse adaptors, how they interact with each other during complex formation, and the role of critical regulators such as lissencephaly-1 (LIS1) protein (LIS1) remain unclear. In this study, we determined the cryo-electron microscopy structure of dynein-dynactin on microtubules with LIS1 and the lysosomal adaptor JIP3. This structure reveals the molecular basis of interactions occurring during dynein activation. We show how JIP3 activates dynein despite its atypical architecture. Unexpectedly, LIS1 binds dynactin's p150 subunit, tethering it along the length of dynein. Our data suggest that LIS1 and p150 constrain dynein-dynactin to ensure efficient complex formation.
Topics: Cryoelectron Microscopy; Dynactin Complex; Dyneins; Microtubule-Associated Proteins; Microtubules; Protein Binding; Humans; HeLa Cells; 1-Alkyl-2-acetylglycerophosphocholine Esterase; Nerve Tissue Proteins; Adaptor Proteins, Signal Transducing; WD40 Repeats; Protein Interaction Mapping
PubMed: 38547289
DOI: 10.1126/science.adk8544 -
MicroPublication Biology 2024Ciliary-dynein preassembly in the cytoplasm is critical for the assembly and movement of motile cilia, organelles that function under viscous conditions. Defects in...
Ciliary-dynein preassembly in the cytoplasm is critical for the assembly and movement of motile cilia, organelles that function under viscous conditions. Defects in preassembly often lead to a reduction in specific types of ciliary dyneins. Here, we investigated how environmental viscosity affects the motility of preassembly-deficient cilia in the alga We found that, depending on the type of ciliary dynein deficiency, each mutant displays a characteristic phenotype in cell propulsion. Our results highlight not only the unique function(s) of each dynein species, but also the importance of functional coordination between dyneins for ciliary motility under viscous conditions.
PubMed: 38545438
DOI: 10.17912/micropub.biology.001149 -
Auris, Nasus, Larynx Jun 2024Primary ciliary dyskinesia (PCD) is a relatively rare genetic disorder that affects approximately 1 in 20,000 people. Approximately 50 genes are currently known to cause... (Review)
Review
OBJECTIVE
Primary ciliary dyskinesia (PCD) is a relatively rare genetic disorder that affects approximately 1 in 20,000 people. Approximately 50 genes are currently known to cause PCD. In light of differences in causative genes and the medical system in Japan compared with other countries, a practical guide was needed for the diagnosis and management of Japanese PCD patients.
METHODS
An ad hoc academic committee was organized under the Japanese Rhinologic Society to produce a practical guide, with participation by committee members from several academic societies in Japan. The practical guide including diagnostic criteria for PCD was approved by the Japanese Rhinologic Society, Japanese Society of Otolaryngology-Head and Neck Surgery, Japanese Respiratory Society, and Japanese Society of Pediatric Pulmonology.
RESULTS
The diagnostic criteria for PCD consist of six clinical features, six laboratory findings, differential diagnosis, and genetic testing. The diagnosis of PCD is categorized as definite, probable, or possible PCD based on a combination of the four items above. Diagnosis of definite PCD requires exclusion of cystic fibrosis and primary immunodeficiency, at least one of the six clinical features, and a positive result for at least one of the following: (1) Class 1 defect on electron microscopy of cilia, (2) pathogenic or likely pathogenic variants in a PCD-related gene, or (3) impairment of ciliary motility that can be repaired by correcting the causative gene variants in iPS cells established from the patient's peripheral blood cells.
CONCLUSION
This practical guide provides clinicians with useful information for the diagnosis and management of PCD in Japan.
Topics: Humans; Kartagener Syndrome; Genetic Testing; Diagnosis, Differential; Cilia; Japan; Axonemal Dyneins; Proteins
PubMed: 38537559
DOI: 10.1016/j.anl.2024.02.001 -
Journal of Cell Science Apr 2024Primary cilia are essential eukaryotic organelles required for signalling and secretion. Dynein-2 is a microtubule-motor protein complex and is required for ciliogenesis...
Primary cilia are essential eukaryotic organelles required for signalling and secretion. Dynein-2 is a microtubule-motor protein complex and is required for ciliogenesis via its role in facilitating retrograde intraflagellar transport (IFT) from the cilia tip to the cell body. Dynein-2 must be assembled and loaded onto IFT trains for entry into cilia for this process to occur, but how dynein-2 is assembled and how it is recycled back into a cilium remain poorly understood. Here, we identify centrosomal protein of 170 kDa (CEP170) as a dynein-2-interacting protein in mammalian cells. We show that loss of CEP170 perturbs intraflagellar transport and hedgehog signalling, and alters the stability of dynein-2 holoenzyme complex. Together, our data indicate a role for CEP170 in supporting cilia function and dynein-2 assembly.
Topics: Cilia; Humans; Microtubule-Associated Proteins; Animals; Dyneins; Hedgehog Proteins; Signal Transduction; Mice; Flagella
PubMed: 38533689
DOI: 10.1242/jcs.261816 -
Trends in Parasitology May 2024Microtubules (MTs) play a vital role as key components of the eukaryotic cytoskeleton. The phylum Apicomplexa comprises eukaryotic unicellular parasitic organisms... (Review)
Review
Microtubules (MTs) play a vital role as key components of the eukaryotic cytoskeleton. The phylum Apicomplexa comprises eukaryotic unicellular parasitic organisms defined by the presence of an apical complex which consists of specialized secretory organelles and tubulin-based cytoskeletal elements. One apicomplexan parasite, Toxoplasma gondii, is an omnipresent opportunistic pathogen with significant medical and veterinary implications. To ensure successful infection and widespread dissemination, T. gondii heavily relies on the tubulin structures present in the apical complex. Recent advances in high-resolution imaging, coupled with reverse genetics, have offered deeper insights into the composition, functionality, and dynamics of these tubulin-based structures. The apicomplexan tubulins differ from those of their mammalian hosts, endowing them with unique attributes and susceptibility to specific classes of inhibitory compounds.
Topics: Toxoplasma; Tubulin; Cytoskeleton; Animals; Microtubules; Humans; Protozoan Proteins
PubMed: 38531711
DOI: 10.1016/j.pt.2024.02.010 -
Journal of Clinical Laboratory Analysis Apr 2024The motor protein dynein is integral to retrograde transport along microtubules and interacts with numerous cargoes through the recruitment of cargo-specific adaptor...
BACKGROUND
The motor protein dynein is integral to retrograde transport along microtubules and interacts with numerous cargoes through the recruitment of cargo-specific adaptor proteins. This interaction is mediated by dynein light intermediate chain subunits LIC1 (DYNC1LI1) and LIC2 (DYNC1LI2), which govern the adaptor binding and are present in distinct dynein complexes with overlapping and unique functions.
METHODS
Using bioinformatics, we analyzed the C-terminal domains (CTDs) of LIC1 and LIC2, revealing similar structural features but diverse post-translational modifications (PTMs). The methylation status of LIC2 and the proteins involved in this modification were examined through immunoprecipitation and immunoblotting analyses. The specific methylation sites on LIC2 were identified through a site-directed mutagenesis analysis, contributing to a deeper understanding of the regulatory mechanisms of the dynein complex.
RESULTS
We found that LIC2 is specifically methylated at the arginine 397 residue, a reaction that is catalyzed by protein arginine methyltransferase 1 (PRMT1).
CONCLUSIONS
The distinct PTMs of the LIC subunits offer a versatile mechanism for dynein to transport diverse cargoes efficiently. Understanding how these PTMs influence the functions of LIC2, and how they differ from LIC1, is crucial for elucidating the role of dynein-related transport pathways in a range of diseases. The discovery of the arginine 397 methylation site on LIC2 enhances our insight into the regulatory PTMs of dynein functions.
Topics: Methylation; Arginine; Humans; Cytoplasmic Dyneins; Protein-Arginine N-Methyltransferases; Protein Processing, Post-Translational; Dyneins; Amino Acid Sequence; Repressor Proteins
PubMed: 38525916
DOI: 10.1002/jcla.25030 -
The American Journal of Case Reports Mar 2024BACKGROUND Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disease that can present at different ages with different phenotypes. Missed and delayed...
BACKGROUND Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disease that can present at different ages with different phenotypes. Missed and delayed diagnoses are fairly common. Many variants in the DNAH5 gene have been described that confirm the diagnosis of PCD. Advances in medicine, especially in molecular genetics, have led to increasingly early discoveries of such cases, especially in those with nonclassical presentations. CASE REPORT This report describes a patient with bronchiectasis, lung cysts, finger clubbing, and failure to thrive who was misdiagnosed for several years as having asthma. Many differentials were suspected and worked up, including a suspicion of PCD. Genetic tests with whole-exome sequencing (WES) and whole-genome sequencing (WGS) detected a heterozygous, likely pathogenic, variant in the DNAH5 gene associated with PCD. CONCLUSIONS Despite a thorough workup done for this case, including a genetic workup, a PCD diagnosis was not established. We plan to reanalyze the WGS in the future, and with advent of technology and better coverage of genes, a genetic answer for this challenging case may resolve this diagnostic quandary in the future.
Topics: Humans; Axonemal Dyneins; Genetic Testing; Kartagener Syndrome; Lung; Mutation
PubMed: 38521969
DOI: 10.12659/AJCR.942444