1
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Power KM, Nguyen KC, Silva A, Singh S, Hall DH, Rongo C, Barr MM. NEKL-4 regulates microtubule stability and mitochondrial health in ciliated neurons. J Cell Biol 2024; 223:e202402006. [PMID: 38767515 PMCID: PMC11104396 DOI: 10.1083/jcb.202402006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/10/2024] [Accepted: 05/06/2024] [Indexed: 05/22/2024] Open
Abstract
Ciliopathies are often caused by defects in the ciliary microtubule core. Glutamylation is abundant in cilia, and its dysregulation may contribute to ciliopathies and neurodegeneration. Mutation of the deglutamylase CCP1 causes infantile-onset neurodegeneration. In C. elegans, ccpp-1 loss causes age-related ciliary degradation that is suppressed by a mutation in the conserved NEK10 homolog nekl-4. NEKL-4 is absent from cilia, yet it negatively regulates ciliary stability via an unknown, glutamylation-independent mechanism. We show that NEKL-4 was mitochondria-associated. Additionally, nekl-4 mutants had longer mitochondria, a higher baseline mitochondrial oxidation state, and suppressed ccpp-1∆ mutant lifespan extension in response to oxidative stress. A kinase-dead nekl-4(KD) mutant ectopically localized to ccpp-1∆ cilia and rescued degenerating microtubule doublet B-tubules. A nondegradable nekl-4(PEST∆) mutant resembled the ccpp-1∆ mutant with dye-filling defects and B-tubule breaks. The nekl-4(PEST∆) Dyf phenotype was suppressed by mutation in the depolymerizing kinesin-8 KLP-13/KIF19A. We conclude that NEKL-4 influences ciliary stability by activating ciliary kinesins and promoting mitochondrial homeostasis.
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Affiliation(s)
- Kaiden M. Power
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Ken C. Nguyen
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Andriele Silva
- Department of Biology, Brooklyn College of the City University of New York, Brooklyn, NY, USA
| | - Shaneen Singh
- Department of Biology, Brooklyn College of the City University of New York, Brooklyn, NY, USA
| | - David H. Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Christopher Rongo
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ, USA
| | - Maureen M. Barr
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
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2
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Power KM, Nguyen KC, Silva A, Singh S, Hall DH, Rongo C, Barr MM. NEKL-4 regulates microtubule stability and mitochondrial health in C. elegans ciliated neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580304. [PMID: 38405845 PMCID: PMC10888866 DOI: 10.1101/2024.02.14.580304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Ciliopathies are often caused by defects in the ciliary microtubule core. Glutamylation is abundant in cilia, and its dysregulation may contribute to ciliopathies and neurodegeneration. Mutation of the deglutamylase CCP1 causes infantile-onset neurodegeneration. In C. elegans, ccpp-1 loss causes age-related ciliary degradation that is suppressed by mutation in the conserved NEK10 homolog nekl-4. NEKL-4 is absent from cilia, yet negatively regulates ciliary stability via an unknown, glutamylation-independent mechanism. We show that NEKL-4 was mitochondria-associated. nekl-4 mutants had longer mitochondria, a higher baseline mitochondrial oxidation state, and suppressed ccpp-1 mutant lifespan extension in response to oxidative stress. A kinase-dead nekl-4(KD) mutant ectopically localized to ccpp-1 cilia and rescued degenerating microtubule doublet B-tubules. A nondegradable nekl-4(PESTΔ) mutant resembled the ccpp-1 mutant with dye filling defects and B-tubule breaks. The nekl-4(PESTΔ) Dyf phenotype was suppressed by mutation in the depolymerizing kinesin-8 KLP-13/KIF19A. We conclude that NEKL-4 influences ciliary stability by activating ciliary kinesins and promoting mitochondrial homeostasis.
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Affiliation(s)
- Kaiden M Power
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
| | - Ken C Nguyen
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY, United States of America
| | - Andriele Silva
- Department of Biology, Brooklyn College of the City University of New York, Brooklyn, NY, United States of America
| | - Shaneen Singh
- Department of Biology, Brooklyn College of the City University of New York, Brooklyn, NY, United States of America
| | - David H Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY, United States of America
| | - Christopher Rongo
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ, United States of America
| | - Maureen M Barr
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
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3
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Bergwell M, Smith A, Smith E, Dierlam C, Duran R, Haastrup E, Napier-Jameson R, Seidel R, Potter W, Norris A, Iyer J. A primary microcephaly-associated sas-6 mutation perturbs centrosome duplication, dendrite morphogenesis, and ciliogenesis in Caenorhabditis elegans. Genetics 2023; 224:iyad105. [PMID: 37279547 PMCID: PMC10411591 DOI: 10.1093/genetics/iyad105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 06/08/2023] Open
Abstract
The human SASS6(I62T) missense mutation has been linked with the incidence of primary microcephaly in a Pakistani family, although the mechanisms by which this mutation causes disease remain unclear. The SASS6(I62T) mutation corresponds to SAS-6(L69T) in Caenorhabditis elegans. Given that SAS-6 is highly conserved, we modeled this mutation in C. elegans and examined the sas-6(L69T) effect on centrosome duplication, ciliogenesis, and dendrite morphogenesis. Our studies revealed that all the above processes are perturbed by the sas-6(L69T) mutation. Specifically, C. elegans carrying the sas-6(L69T) mutation exhibit an increased failure of centrosome duplication in a sensitized genetic background. Further, worms carrying this mutation also display shortened phasmid cilia, an abnormal phasmid cilia morphology, shorter phasmid dendrites, and chemotaxis defects. Our data show that the centrosome duplication defects caused by this mutation are only uncovered in a sensitized genetic background, indicating that these defects are mild. However, the ciliogenesis and dendritic defects caused by this mutation are evident in an otherwise wild-type background, indicating that they are stronger defects. Thus, our studies shed light on the novel mechanisms by which the sas-6(L69T) mutation could contribute to the incidence of primary microcephaly in humans.
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Affiliation(s)
- Mary Bergwell
- Oklahoma Medical Research Foundation, Cell Cycle & Cancer Biology Research Program, Oklahoma City, OK 73104, USA
| | - Amy Smith
- Pfizer Inc., Pharmaceutical R&D – Drug Product Design & Development, Chesterfield, MO 63017, USA
| | - Ellie Smith
- University of Tulsa, Department of Chemistry and Biochemistry, Tulsa, OK 74104, USA
| | - Carter Dierlam
- University of Tulsa, Department of Chemistry and Biochemistry, Tulsa, OK 74104, USA
| | - Ramon Duran
- University of Tulsa, Department of Chemistry and Biochemistry, Tulsa, OK 74104, USA
| | - Erin Haastrup
- University of Tulsa, Department of Chemistry and Biochemistry, Tulsa, OK 74104, USA
| | | | - Rory Seidel
- University of Tulsa, Department of Chemistry and Biochemistry, Tulsa, OK 74104, USA
| | - William Potter
- University of Tulsa, Department of Chemistry and Biochemistry, Tulsa, OK 74104, USA
| | - Adam Norris
- Southern Methodist University, Department of Biological Sciences, Dallas, TX 75275, USA
| | - Jyoti Iyer
- University of Tulsa, Department of Chemistry and Biochemistry, Tulsa, OK 74104, USA
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4
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Mill P, Christensen ST, Pedersen LB. Primary cilia as dynamic and diverse signalling hubs in development and disease. Nat Rev Genet 2023; 24:421-441. [PMID: 37072495 PMCID: PMC7615029 DOI: 10.1038/s41576-023-00587-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2023] [Indexed: 04/20/2023]
Abstract
Primary cilia, antenna-like sensory organelles protruding from the surface of most vertebrate cell types, are essential for regulating signalling pathways during development and adult homeostasis. Mutations in genes affecting cilia cause an overlapping spectrum of >30 human diseases and syndromes, the ciliopathies. Given the immense structural and functional diversity of the mammalian cilia repertoire, there is a growing disconnect between patient genotype and associated phenotypes, with variable severity and expressivity characteristic of the ciliopathies as a group. Recent technological developments are rapidly advancing our understanding of the complex mechanisms that control biogenesis and function of primary cilia across a range of cell types and are starting to tackle this diversity. Here, we examine the structural and functional diversity of primary cilia, their dynamic regulation in different cellular and developmental contexts and their disruption in disease.
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Affiliation(s)
- Pleasantine Mill
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland
| | | | - Lotte B Pedersen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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5
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O'Hagan R, Avrutis A, Ramicevic E. Functions of the tubulin code in the C. elegans nervous system. Mol Cell Neurosci 2022; 123:103790. [PMID: 36368428 DOI: 10.1016/j.mcn.2022.103790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 10/27/2022] [Accepted: 11/03/2022] [Indexed: 11/11/2022] Open
Abstract
Due to their elongated and polarized morphology, neurons rely on the microtubule (MT) cytoskeleton for their shape, as well as for efficient intracellular transport that maintains neuronal function, survival, and connectivity. Although all MTs are constructed from α- and β-tubulins that are highly conserved throughout eukaryotes, different MT networks within neurons exhibit different dynamics and functions. For example, molecular motors must be able to differentially recognize the axonal and dendritic MTs to deliver appropriate cargos to sensory endings and synaptic regions. The Tubulin Code hypothesis proposes that MTs can be specialized in form and function by chemical differences in their composition by inclusion of different α- and β-tubulins into the MT lattice, as well as differences in post-translational enzymatic modifications. The chemical differences encode information that allow MTs to regulate interactions with various microtubule-based molecular motors such as kinesins and dyneins as well as with structural microtubule-associated proteins (MAPs), which can, in turn, modify the function or stability of MTs. Here, we review studies involving C. elegans, a model organism with a relatively simple nervous system that is amenable to genetic analysis, that have contributed to our understanding of how the Tubulin Code can specialize neuronal MT networks to establish differences in neuronal morphology and function. Such studies have revealed molecules and mechanisms that are conserved in vertebrates and have the potential to inform our understanding of neurological diseases involving defects in the cytoskeleton and intracellular transport.
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Affiliation(s)
- Robert O'Hagan
- formerly at Biology Dept., Montclair State University, Montclair, NJ 07043, United States of America.
| | - Alexandra Avrutis
- formerly at Biology Dept., Montclair State University, Montclair, NJ 07043, United States of America
| | - Ema Ramicevic
- formerly at Biology Dept., Montclair State University, Montclair, NJ 07043, United States of America
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6
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Mechanisms of Regulation in Intraflagellar Transport. Cells 2022; 11:cells11172737. [PMID: 36078145 PMCID: PMC9454703 DOI: 10.3390/cells11172737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 08/30/2022] [Accepted: 08/31/2022] [Indexed: 11/30/2022] Open
Abstract
Cilia are eukaryotic organelles essential for movement, signaling or sensing. Primary cilia act as antennae to sense a cell’s environment and are involved in a wide range of signaling pathways essential for development. Motile cilia drive cell locomotion or liquid flow around the cell. Proper functioning of both types of cilia requires a highly orchestrated bi-directional transport system, intraflagellar transport (IFT), which is driven by motor proteins, kinesin-2 and IFT dynein. In this review, we explore how IFT is regulated in cilia, focusing from three different perspectives on the issue. First, we reflect on how the motor track, the microtubule-based axoneme, affects IFT. Second, we focus on the motor proteins, considering the role motor action, cooperation and motor-train interaction plays in the regulation of IFT. Third, we discuss the role of kinases in the regulation of the motor proteins. Our goal is to provide mechanistic insights in IFT regulation in cilia and to suggest directions of future research.
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7
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Guo X, Wang R, Ma R, Fan X, Gao Y, Zhang X, Yuchi Z, Wu HY. Facile purification of active recombinant mouse cytosolic carboxypeptidase 6 from Escherichia coli. Protein Expr Purif 2022; 197:106112. [DOI: 10.1016/j.pep.2022.106112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 05/10/2022] [Accepted: 05/16/2022] [Indexed: 11/16/2022]
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8
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Lu YM, Zheng C. The Expression and Function of Tubulin Isotypes in Caenorhabditis elegans. Front Cell Dev Biol 2022; 10:860065. [PMID: 35399537 PMCID: PMC8987236 DOI: 10.3389/fcell.2022.860065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 02/28/2022] [Indexed: 11/13/2022] Open
Abstract
Microtubules, made from the polymerization of the highly conserved α/β-tubulin heterodimers, serve as important components of the cytoskeleton in all eukaryotic cells. The existence of multiple tubulin isotypes in metazoan genomes and a dazzling variety of tubulin posttranslational modifications (PTMs) prompted the “tubulin code” hypothesis, which proposed that microtubule structure and functions are determined by the tubulin composition and PTMs. Evidence for the tubulin code has emerged from studies in several organisms with the characterization of specific tubulins for their expression and functions. The studies of tubulin PTMs are accelerated by the discovery of the enzymes that add or remove the PTMs. In tubulin research, the use of simple organisms, such as Caenorhabditis elegans, has been instrumental for understanding the expression and functional specialization of tubulin isotypes and the effects of their PTMs. In this review, we summarize the current understanding of the expression patterns and cellular functions of the nine α-tubulin and six β-tubulin isotypes. Expression studies are greatly facilitated by the CRISPR/Cas9-mediated endogenous GFP knock-in reporters and the organism-wide single cell transcriptomic studies. Meanwhile, functional studies benefit from the ease of genetic manipulation and precise gene replacement in C. elegans. These studies identified both ubiquitously expressed tubulin isotypes and tissue-specific isotypes. The isotypes showed functional redundancy, as well as functional specificity, which is likely caused by the subtle differences in their amino acid sequences. Many of these differences concentrate at the C-terminal tails that are subjected to several PTMs. Indeed, tubulin PTM, such as polyglutamylation, is shown to modulate microtubule organization and properties in both ciliated and non-ciliated neurons. Overall, studies from C. elegans support the distinct expression and function patterns of tubulin isotypes and the importance of their PTMs and offer the promise of cracking the tubulin code at the whole-genome and the whole-organism level.
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9
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O'Hagan R, Topalidou I. Fixation and Immunostaining of Endogenous Proteins or Post-translational Modificationsin Caenorhabditis elegans. Bio Protoc 2021; 11:e4172. [PMID: 34722819 DOI: 10.21769/bioprotoc.4172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 06/10/2021] [Accepted: 06/16/2021] [Indexed: 11/02/2022] Open
Abstract
Although the advent of genetically-encoded fluorescent markers, such as the green fluorescent protein (GFP; Chalfie et al., 1994 ), has enabled convenient visualization of gene expression in vivo, this method is generally not effective for detecting post-translational modifications because they are not translated from DNA sequences. Genetically-encoded, fluorescently-tagged transgene products can also be misleading for observing expression patterns because transgenes may lack endogenous regulatory DNA elements needed for precise regulation of expression that could result in over or under expression. Fluorescently-tagged proteins created by CRISPR genome editing are less prone to defective expression patterns because the loci retain endogenous DNA elements that regulate their transcription (Nance and Frøkjær-Jensen, 2019). However, even CRISPR alleles encoding heritable fluorescently-tagged protein markers can result in defects in function or localization of the gene product if the fluorescent tag obstructs or otherwise interferes with important protein interaction domains or affects the protein structure. Indirect immunofluorescence is a method for detecting endogenous gene expression or post-translational modifications without the need for transgenesis or genome editing. Here, we present a reliable protocol in which C. elegans nematodes are fixed, preserved, and permeabilized for staining with a primary antibody to bind proteins or post-translational modifications, which are then labeled with a secondary antibody conjugated to a fluorescent dye. Use of this method may be limited by the availability of (or ability to generate) a primary antibody that binds the epitope of interest in fixed animals. Thousands of animals are simultaneously subjected to a series of chemical treatments and washes in a single centrifuge tube, allowing large numbers of identically-treated stained animals to be examined. We have successfully used this protocol (O' Hagan et al., 2011 and 2017; Power et al., 2020 ) to preserve and detect post-translational modifications of tubulin in C. elegans ciliated sensory neurons and to detect non-modified endogenous protein (Topalidou and Chalfie, 2011).
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Affiliation(s)
- Robert O'Hagan
- Biology Department, Montclair State University, Montclair, USA
| | - Irini Topalidou
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
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10
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Li D, Liu Y, Yi P, Zhu Z, Li W, Zhang QC, Li JB, Ou G. RNA editing restricts hyperactive ciliary kinases. Science 2021; 373:984-991. [PMID: 34446600 DOI: 10.1126/science.abd8971] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 04/01/2021] [Accepted: 07/16/2021] [Indexed: 12/17/2022]
Abstract
Protein kinase activity must be precisely regulated, but how a cell governs hyperactive kinases remains unclear. In this study, we generated a constitutively active mitogen-activated protein kinase DYF-5 (DYF-5CA) in Caenorhabditis elegans that disrupted sensory cilia. Genetic suppressor screens identified that mutations of ADR-2, an RNA adenosine deaminase, rescued ciliary phenotypes of dyf-5CA We found that dyf-5CA animals abnormally transcribed antisense RNAs that pair with dyf-5CA messenger RNA (mRNA) to form double-stranded RNA, recruiting ADR-2 to edit the region ectopically. RNA editing impaired dyf-5CA mRNA splicing, and the resultant intron retentions blocked DYF-5CA protein translation and activated nonsense-mediated dyf-5CA mRNA decay. The kinase RNA editing requires kinase hyperactivity. The similar RNA editing-dependent feedback regulation restricted the other ciliary kinases NEKL-4/NEK10 and DYF-18/CCRK, which suggests a widespread mechanism that underlies kinase regulation.
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Affiliation(s)
- Dongdong Li
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China.,Beijing Frontier Research Center for Biological Structure, Tsinghua University, Beijing, China.,McGovern Institute for Brain Research, Tsinghua University, Beijing, China.,School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Yufan Liu
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China.,Beijing Frontier Research Center for Biological Structure, Tsinghua University, Beijing, China.,McGovern Institute for Brain Research, Tsinghua University, Beijing, China.,School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Peishan Yi
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China.,Beijing Frontier Research Center for Biological Structure, Tsinghua University, Beijing, China.,McGovern Institute for Brain Research, Tsinghua University, Beijing, China.,School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Zhiwen Zhu
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China.,Beijing Frontier Research Center for Biological Structure, Tsinghua University, Beijing, China.,McGovern Institute for Brain Research, Tsinghua University, Beijing, China.,School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Wei Li
- School of Medicine, Tsinghua University, Beijing, China
| | - Qiangfeng Cliff Zhang
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China.,Beijing Frontier Research Center for Biological Structure, Tsinghua University, Beijing, China.,MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, China.,Center for Synthetic and Systems Biology, Tsinghua University, Beijing, China
| | - Jin Billy Li
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Guangshuo Ou
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China. .,Beijing Frontier Research Center for Biological Structure, Tsinghua University, Beijing, China.,McGovern Institute for Brain Research, Tsinghua University, Beijing, China.,School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
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11
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Mathieu H, Patten SA, Aragon-Martin JA, Ocaka L, Simpson M, Child A, Moldovan F. Genetic variant of TTLL11 gene and subsequent ciliary defects are associated with idiopathic scoliosis in a 5-generation UK family. Sci Rep 2021; 11:11026. [PMID: 34040021 PMCID: PMC8155187 DOI: 10.1038/s41598-021-90155-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 05/04/2021] [Indexed: 02/07/2023] Open
Abstract
Idiopathic scoliosis (IS) is a complex 3D deformation of the spine with a strong genetic component, most commonly found in adolescent girls. Adolescent idiopathic scoliosis (AIS) affects around 3% of the general population. In a 5-generation UK family, linkage analysis identified the locus 9q31.2-q34.2 as a candidate region for AIS; however, the causative gene remained unidentified. Here, using exome sequencing we identified a rare insertion c.1569_1570insTT in the tubulin tyrosine ligase like gene, member 11 (TTLL11) within that locus, as the IS causative gene in this British family. Two other TTLL11 mutations were also identified in two additional AIS cases in the same cohort. Analyses of primary cells of individuals carrying the c.1569_1570insTT (NM_194252) mutation reveal a defect at the primary cilia level, which is less present, smaller and less polyglutamylated compared to control. Further, in a zebrafish, the knock down of ttll11, and the mutated ttll11 confirmed its role in spine development and ciliary function in the fish retina. These findings provide evidence that mutations in TTLL11, a ciliary gene, contribute to the pathogenesis of IS.
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Affiliation(s)
- Hélène Mathieu
- CHU Sainte-Justine Research Center, 3175 Côte Sainte-Catherine, 2.17.026, Montreal, QC, H3T 1C5, Canada
| | - Shunmoogum A Patten
- INRS-Centre Armand-Frappier Santé et Biotechnologie, Laval, QC, H7V1B7, Canada
| | | | - Louise Ocaka
- Centre for Translational Omics-GOSgene, Department of Genetics and Genomic Medicine, UCL GOSH Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK
| | - Michael Simpson
- Genetics and Molecular Medicine, King's College London, SE1 1UL, London, UK
| | - Anne Child
- Marfan Trust, NHLI, Imperial College, Guy Scadding Building, London, SW3 6LY, UK.
| | - Florina Moldovan
- CHU Sainte-Justine Research Center, 3175 Côte Sainte-Catherine, 2.17.026, Montreal, QC, H3T 1C5, Canada. .,Faculty of Dentistry, Université de Montréal, Montreal, QC, H3T 1J4, Canada.
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12
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Akella JS, Barr MM. The tubulin code specializes neuronal cilia for extracellular vesicle release. Dev Neurobiol 2021; 81:231-252. [PMID: 33068333 PMCID: PMC8052387 DOI: 10.1002/dneu.22787] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 09/07/2020] [Accepted: 09/23/2020] [Indexed: 12/17/2022]
Abstract
Cilia are microtubule-based organelles that display diversity in morphology, ultrastructure, protein composition, and function. The ciliary microtubules of C. elegans sensory neurons exemplify this diversity and provide a paradigm to understand mechanisms driving ciliary specialization. Only a subset of ciliated neurons in C. elegans are specialized to make and release bioactive extracellular vesicles (EVs) into the environment. The cilia of extracellular vesicle releasing neurons have distinct axonemal features and specialized intraflagellar transport that are important for releasing EVs. In this review, we discuss the role of the tubulin code in the specialization of microtubules in cilia of EV releasing neurons.
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Affiliation(s)
- Jyothi S Akella
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Maureen M Barr
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
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13
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CCP1, a Tubulin Deglutamylase, Increases Survival of Rodent Spinal Cord Neurons following Glutamate-Induced Excitotoxicity. eNeuro 2021; 8:ENEURO.0431-20.2021. [PMID: 33688040 PMCID: PMC8021396 DOI: 10.1523/eneuro.0431-20.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/25/2021] [Accepted: 02/12/2021] [Indexed: 01/21/2023] Open
Abstract
Microtubules (MTs) are cytoskeletal elements that provide structural support and act as roadways for intracellular transport in cells. MTs are also needed for neurons to extend and maintain long axons and dendrites that establish connectivity to transmit information through the nervous system. Therefore, in neurons, the ability to independently regulate cytoskeletal stability and MT-based transport in different cellular compartments is essential. Posttranslational modification of MTs is one mechanism by which neurons regulate the cytoskeleton. The carboxypeptidase CCP1 negatively regulates posttranslational polyglutamylation of MTs. In mammals, loss of CCP1, and the resulting hyperglutamylation of MTs, causes neurodegeneration. It has also long been known that CCP1 expression is activated by neuronal injury; however, whether CCP1 plays a neuroprotective role after injury is unknown. Using shRNA-mediated knock-down of CCP1 in embryonic rat spinal cord cultures, we demonstrate that CCP1 protects spinal cord neurons from excitotoxic death. Unexpectedly, excitotoxic injury reduced CCP1 expression in our system. We previously demonstrated that the CCP1 homolog in Caenorhabditis elegans is important for maintenance of neuronal cilia. Although cilia enhance neuronal survival in some contexts, it is not yet clear whether CCP1 maintains cilia in mammalian spinal cord neurons. We found that knock-down of CCP1 did not result in loss or shortening of cilia in cultured spinal cord neurons, suggesting that its effect on survival of excitotoxicity is independent of cilia. Our results support the idea that enzyme regulators of MT polyglutamylation might be therapeutically targeted to prevent excitotoxic death after spinal cord injuries.
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14
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Yang WT, Hong SR, He K, Ling K, Shaiv K, Hu J, Lin YC. The Emerging Roles of Axonemal Glutamylation in Regulation of Cilia Architecture and Functions. Front Cell Dev Biol 2021; 9:622302. [PMID: 33748109 PMCID: PMC7970040 DOI: 10.3389/fcell.2021.622302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 02/11/2021] [Indexed: 12/14/2022] Open
Abstract
Cilia, which either generate coordinated motion or sense environmental cues and transmit corresponding signals to the cell body, are highly conserved hair-like structures that protrude from the cell surface among diverse species. Disruption of ciliary functions leads to numerous human disorders, collectively referred to as ciliopathies. Cilia are mechanically supported by axonemes, which are composed of microtubule doublets. It has been recognized for several decades that tubulins in axonemes undergo glutamylation, a post-translational polymodification, that conjugates glutamic acid chains onto the C-terminal tail of tubulins. However, the physiological roles of axonemal glutamylation were not uncovered until recently. This review will focus on how cells modulate glutamylation on ciliary axonemes and how axonemal glutamylation regulates cilia architecture and functions, as well as its physiological importance in human health. We will also discuss the conventional and emerging new strategies used to manipulate glutamylation in cilia.
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Affiliation(s)
- Wen-Ting Yang
- Institute of Molecular Medicine, National Tsing Hua University, HsinChu City, Taiwan
| | - Shi-Rong Hong
- Institute of Molecular Medicine, National Tsing Hua University, HsinChu City, Taiwan
| | - Kai He
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, United States
| | - Kun Ling
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, United States
| | - Kritika Shaiv
- Institute of Molecular Medicine, National Tsing Hua University, HsinChu City, Taiwan
| | - JingHua Hu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, United States
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, United States
- Mayo Clinic Robert and Arlene Kogod Center on Aging, Mayo Clinic, Rochester, MN, United States
| | - Yu-Chun Lin
- Institute of Molecular Medicine, National Tsing Hua University, HsinChu City, Taiwan
- Department of Medical Science, National Tsing Hua University, HsinChu City, Taiwan
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