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Zhou Q, Fu Z, Li M, Shen Q, Sun C, Feng Y, Liu Y, Jiang J, Qin T, Mao T, Hearne SJ, Wang G, Tang J. Maize tubulin folding cofactor B is required for cell division and cell growth through modulating microtubule homeostasis. THE NEW PHYTOLOGIST 2023. [PMID: 36843261 DOI: 10.1111/nph.18839] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
Tubulin folding cofactors (TFCs) are required for tubulin folding, α/β tubulin heterodimer formation, and microtubule (MT) dynamics in yeast and mammals. However, the functions of their plant counterparts remain to be characterized. We identified a natural maize crumpled kernel mutant, crk2, which exhibits reductions in endosperm cell number and size, as well as embryo/seedling lethality. Map-based cloning and functional complementation confirmed that ZmTFCB is causal for the mutation. ZmTFCB is targeted mainly to the cytosol. It facilitates α-tubulin folding and heterodimer formation through sequential interactions with the cytosolic chaperonin-containing TCP-1 ε subunit ZmCCT5 and ZmTFCE, thus affecting the organization of both the spindle and phragmoplast MT array and the cortical MT polymerization and array formation, which consequently mediated cell division and cell growth. We detected a physical association between ZmTFCB and the maize MT plus-end binding protein END-BINDING1 (ZmEB1), indicating that ZmTFCB1 may modulate MT dynamics by sequestering ZmEB1. Our data demonstrate that ZmTFCB is required for cell division and cell growth through modulating MT homeostasis, an evolutionarily conserved machinery with some species-specific divergence.
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Affiliation(s)
- Qingqian Zhou
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Zhiyuan Fu
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Mengyuan Li
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Qingwen Shen
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Canran Sun
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Yijian Feng
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Yang Liu
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Jianjun Jiang
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Tao Qin
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Tonglin Mao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Sarah Jane Hearne
- CIMMYT, KM 45 Carretera Mexico-Veracruz, El Batan, Texcoco, Estado de México, 56237, Mexico
| | - Guifeng Wang
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Jihua Tang
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
- The Shennong Laboratory, Zhengzhou, Henan, 450002, China
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2
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Ganne A, Balasubramaniam M, Ayyadevara H, Kiaei L, Shmookler Reis RJ, Varughese KI, Kiaei M. In silico analysis of TUBA4A mutations in Amyotrophic Lateral Sclerosis to define mechanisms of microtubule disintegration. Sci Rep 2023; 13:2096. [PMID: 36747013 PMCID: PMC9902468 DOI: 10.1038/s41598-023-28381-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 01/18/2023] [Indexed: 02/08/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is an inexorably progressive and degenerative disorder of motor neurons with no currently-known cure. Studies to determine the mechanism of neurotoxicity and the impact of ALS-linked mutations (SOD1, FUS, TARDP, C9ORF72, PFN1, TUBA4A and others) have greatly expanded our knowledge of ALS disease mechanisms and have helped to identify potential targets for ALS therapy. Cellular pathologies (e.g., aggregation of mutant forms of SOD1, TDP43, FUS, Ubiqulin2, PFN1, and C9ORF72), mitochondrial dysfunction, neuroinflammation, and oxidative damage are major pathways implicated in ALS. Nevertheless, the selective vulnerability of motor neurons remains unexplained. The importance of tubulins for long-axon infrastructure, and the special morphology and function of motor neurons, underscore the central role of the cytoskeleton. The recent linkage of mutations to the tubulin α chain, TUBA4A, to familial and sporadic cases of ALS provides a new investigative opportunity to shed light on both mechanisms of ALS and the vulnerability of motor neurons. In the current study we investigate TUBA4A, a structural microtubule protein with mutations causal to familial ALS, using molecular-dynamic (MD) modeling of protein structure to predict the effects of each mutation and its overall impact on GTP binding, chain stability, tubulin assembly, and aggregation propensity. These studies predict that each of the reported mutations will cause notable structural changes to the TUBA4A (α chain) tertiary protein structure, adversely affecting its physical properties and functions. Molecular docking and MD simulations indicate certain α chain mutations (e.g. K430N, R215C, and W407X) may cause structural deviations that impair GTP binding, and plausibly prevent or destabilize tubulin polymerization. Furthermore, several mutations (including R320C and K430N) confer a significant increase in predicted aggregation propensity of TUBA4A mutants relative to wild-type. Taken together, these in silico modeling studies predict structural perturbations and disruption of GTP binding, culminating in failure to form a stable tubulin heterocomplex, which may furnish an important pathogenic mechanism to trigger motor neuron degeneration in ALS.
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Affiliation(s)
- Akshatha Ganne
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA
| | - Meenakshisundaram Balasubramaniam
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA.,Central Arkansas Veterans Healthcare Service, McClellan Veterans Medical Center, Little Rock, AR, 72205, USA.,SiBioLead, LLC, Little Rock, AR, 72207, USA
| | | | - Lily Kiaei
- University of California, Los Angeles, Los Angeles, CA, 90095, USA.,RockGen Therapeutics, LLC, Little Rock, AR, 72205, USA
| | - Robert J Shmookler Reis
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA.,Central Arkansas Veterans Healthcare Service, McClellan Veterans Medical Center, Little Rock, AR, 72205, USA.,SiBioLead, LLC, Little Rock, AR, 72207, USA
| | - Kottayil I Varughese
- Department of Physiology and Cell Biology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA
| | - Mahmoud Kiaei
- RockGen Therapeutics, LLC, Little Rock, AR, 72205, USA. .,Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA. .,Department of Neurology, University of Arkansas for Medical Sciences, 4301 W. Markham St., Slot 611 (BioMed 1, Rm B-306A), Little Rock, AR, 72205, USA.
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3
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Ocampo-Chih C, Dennis H, Lall N, Pham N, Liang B, Verma S, Neira Fresneda J. PEBAT, an Intriguing Neurodegenerative Tubulinopathy Caused by a Novel Homozygous Variant in TBCD: A Case Series and Literature Review. Pediatr Neurol 2023; 139:59-64. [PMID: 36527993 DOI: 10.1016/j.pediatrneurol.2022.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 10/20/2022] [Accepted: 11/08/2022] [Indexed: 11/25/2022]
Abstract
Progressive encephalopathy with brain atrophy and thin corpus callosum (PEBAT) is a severe and rare progressive neurodegenerative disease (OMIM 617913). This condition has been described in individuals with pathogenic variants affecting tubulin-specific chaperone protein D (TBCD), which is responsible for proper folding and assembly of tubulin subunits. Here we describe two unrelated infants from Central America presenting with worsening neuromuscular weakness, respiratory failure, polyneuropathy, and neuroimaging findings of severe cerebral volume loss with thin corpus callosum. These individuals harbored the same homozygous variant of uncertain significance in the TBCD gene on whole exome sequencing (WES). Predicted protein modeling of this variant confirmed disruption of the protein helix at the surface of TBCD. The goal of this report is to emphasize the importance of rapid WES, careful interpretation of uncertain variants, prognostication, and family counseling especially when faced with a neurodegenerative clinical course.
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Affiliation(s)
- Claudia Ocampo-Chih
- Monroe Carell Jr. Children's Hospital, Vanderbilt University, Nashville, Tennessee
| | - Hailey Dennis
- Department of Medical Genetics, Emory University School of Medicine, Atlanta, Georgia
| | - Neil Lall
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia; Department of Radiology, Emory University School of Medicine, Atlanta, Georgia
| | - Nga Pham
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia; Department of Pediatric Critical Care Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Bo Liang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia
| | - Sumit Verma
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia; Department of Neurology, Emory University School of Medicine, Atlanta, Georgia
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4
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Pinho-Correia LM, Prokop A. Maintaining essential microtubule bundles in meter-long axons: a role for local tubulin biogenesis? Brain Res Bull 2023; 193:131-145. [PMID: 36535305 DOI: 10.1016/j.brainresbull.2022.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 12/12/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022]
Abstract
Axons are the narrow, up-to-meter long cellular processes of neurons that form the biological cables wiring our nervous system. Most axons must survive for an organism's lifetime, i.e. up to a century in humans. Axonal maintenance depends on loose bundles of microtubules that run without interruption all along axons. The continued turn-over and the extension of microtubule bundles during developmental, regenerative or plastic growth requires the availability of α/β-tubulin heterodimers up to a meter away from the cell body. The underlying regulation in axons is poorly understood and hardly features in past and contemporary research. Here we discuss potential mechanisms, particularly focussing on the possibility of local tubulin biogenesis in axons. Current knowledge might suggest that local translation of tubulin takes place in axons, but far less is known about the post-translational machinery of tubulin biogenesis involving three chaperone complexes: prefoldin, CCT and TBC. We discuss functional understanding of these chaperones from a range of model organisms including yeast, plants, flies and mice, and explain what is known from human diseases. Microtubules across species depend on these chaperones, and they are clearly required in the nervous system. However, most chaperones display a high degree of functional pleiotropy, partly through independent functions of individual subunits outside their complexes, thus posing a challenge to experimental studies. Notably, we found hardly any studies that investigate their presence and function particularly in axons, thus highlighting an important gap in our understanding of axon biology and pathology.
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Affiliation(s)
- Liliana Maria Pinho-Correia
- The University of Manchester, Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, School of Biology, Manchester, UK
| | - Andreas Prokop
- The University of Manchester, Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, School of Biology, Manchester, UK.
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5
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Zheng Y, Yang M, Chen X, Zhang G, Wan S, Zhang B, Huo J, Liu H. Decreased tubulin-binding cofactor B was involved in the formation disorder of nascent astrocyte processes by regulating microtubule plus-end growth through binding with end-binding proteins 1 and 3 after chronic alcohol exposure. Front Cell Neurosci 2022; 16:989945. [PMID: 36385945 PMCID: PMC9641617 DOI: 10.3389/fncel.2022.989945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Accepted: 09/21/2022] [Indexed: 11/30/2022] Open
Abstract
Fetal alcohol syndrome (FAS) is a neurological disease caused by excessive drinking during pregnancy and characterized by congenital abnormalities in the structure and function of the fetal brain. This study was proposed to provide new insights into the pathogenesis of FAS by revealing the possible mechanisms of alcohol-induced astrocyte injury. First, a chronic alcohol exposure model of astrocytes was established, and the formation disorder was found in astrocyte processes where tubulin-binding cofactor B (TBCB) was decreased or lost, accompanied by disorganized microtubules (MT). Second, to understand the relationship between TBCB reduction and the formation disorder of astrocyte processes, TBCB was silenced or overexpressed. It caused astrocyte processes to retract or lose after silencing, while the processes increased with expending basal part and obtuse tips after overexpressing. It confirmed that TBCB was one of the critical factors for the formation of astrocyte processes through regulating MT plus-end and provided a new view on the pathogenesis of FAS. Third, to explore the mechanism of TBCB regulating MT plus-ends, we first proved end-binding proteins 1 and 3 (EB1/3) were bound at MT plus-ends in astrocytes. Then, through interference experiments, we found that both EB1 and EB3, which formed in heterodimers, were necessary to mediate TBCB binding to MT plus-ends and thus regulated the formation of astrocyte processes. Finally, the regulatory mechanism was studied and the ERK1/2 signaling pathway was found as one of the main pathways regulating the expression of TBCB in astrocytes after alcohol injury.
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Affiliation(s)
- Yin Zheng
- Institute of Neuroscience, Chongqing Medical University, Chongqing, China
- Department of Basic Medicine, Chongqing College of Traditional Chinese Medicine, Chongqing, China
| | - Mei Yang
- Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Xiaoqiao Chen
- Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Gaoli Zhang
- Institute for Viral Hepatitis, Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Shanshan Wan
- Department of Blood Transfusion, Sichuan Cancer Hospital and Institute, Chengdu, China
| | - Bingqiu Zhang
- Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Jiechao Huo
- Fujian Province University Engineering Research Center of Mindong She Medicine, Medical College, Ningde Normal University, Ningde, China
| | - Hui Liu
- Institute of Neuroscience, Chongqing Medical University, Chongqing, China
- *Correspondence: Hui Liu
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6
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Guo Y, Chen Y, Zhang J, Li J, Fan K, Chen R, Liu Y, Zheng J, Fu J, Gu R, Wang G, Cui Y, Du X, Wang J. Epigenetic Mutation in a Tubulin-Folding Cofactor B (ZmTFCB) Gene Arrests Kernel Development in Maize. PLANT & CELL PHYSIOLOGY 2022; 63:1156-1167. [PMID: 35771678 DOI: 10.1093/pcp/pcac092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 06/26/2022] [Accepted: 06/29/2022] [Indexed: 06/15/2023]
Abstract
Epialleles, the heritable epigenetic variants that are not caused by changes in DNA sequences, can broaden genetic and phenotypic diversity and benefit to crop breeding, but very few epialleles related to agricultural traits have been identified in maize. Here, we cloned a small kernel mutant, smk-wl10, from maize, which encoded a tubulin-folding cofactor B (ZmTFCB) protein. Expression of the ZmTFCB gene decreased in the smk-wl10 mutant, which arrested embryo, endosperm and basal endosperm transfer layer developments. Overexpression of ZmTFCB could complement the defective phenotype of smk-wl10. No nucleotide sequence variation in ZmTFCB could be found between smk-wl10 and wild type (WT). Instead, we detected hypermethylation of nucleotide CHG (where H is A, C or T nucleotide) sequence contexts and increased level of histone H3K9me2 methylation in the upstream sequence of ZmTFCB in smk-wl10 compared with WT, which might respond to the attenuating transcription of ZmTFCB. In addition, yeast two-hybrid and bimolecular fluorescence complementation assays identified a strong interaction between ZmTFCB and its homolog ZmTFCE. Thus, our work identifies a novel epiallele of the maize ZmTFCB gene, which might represent a common phenomenon in the epigenetic regulation of important traits such as kernel development in maize.
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Affiliation(s)
- Yingmei Guo
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Yan Chen
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
- Hainan Yazhou Bay Seed Laboratory, Sanya 572025, China
| | - Jie Zhang
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Jiankun Li
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Kaijian Fan
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Rongrong Chen
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Yunjun Liu
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Jun Zheng
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Junjie Fu
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Riliang Gu
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Guoying Wang
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Yu Cui
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Xuemei Du
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Jianhua Wang
- Beijing Innovation Center for Crop Seed Technology, Ministry of Agriculture and Rural Affairs, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
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Fei CF, Zhou LQ. Gene mutations impede oocyte maturation, fertilization, and early embryonic development. Bioessays 2022; 44:e2200007. [PMID: 35900055 DOI: 10.1002/bies.202200007] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 12/11/2022]
Abstract
Reproductive diseases are a long-standing problem and have become more common in the world. Currently, 15% of the world's population suffers from infertility, and half of them are women. Maturation of oocytes, successful fertilization, and high-quality embryos are prerequisites for pregnancy. With the development of assisted reproductive technology and advanced genetic assays, we have found that infertility in many young female patients is caused by mutations in various developmental regulators. These pathogenic factors may result in impediment of oocyte maturation, failure of fertilization or early embryonic development arrest. In this review, we categorize these clinically-identified, mutated genetic factors by their molecular characteristics: nuclear factors (PALT2, TRIP13, WEE2, TBPL2, REC114, MEI1 and CDC20), cytoplasmic factors (TLE6, PADI6, NLRP2/5, FBXO43, MOS and BTG4), a factor unique to primates (TUBB8), cell membrane factor (PANX1), and zona pellucida factors (ZP1-3). We compared discrepancies observed in phenotypes between human and mouse models to provide clues for clinical diagnosis and treatment of related reproductive diseases.
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Affiliation(s)
- Cai-Feng Fei
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Li-Quan Zhou
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
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8
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Prins R, Windsor P, Miller BR, Maiden S. Alleles of unc-33/CRMP exhibit defects during Caenorhabditis elegans epidermal morphogenesis. Dev Dyn 2022; 251:1741-1753. [PMID: 35538612 DOI: 10.1002/dvdy.497] [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: 03/11/2021] [Revised: 04/16/2022] [Accepted: 04/27/2022] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND Microtubule-associated proteins regulate the dynamics, organization, and function of microtubules, impacting a number of vital cellular processes. CRMPs have been shown to control microtubule assembly and axon outgrowth during neuronal differentiation. While many microtubule-associated proteins have been linked to roles in cell division and neuronal development, it is still unclear the complement that control the formation of parallel microtubule arrays in epithelial cells. RESULTS Here we show through time-lapse DIC microscopy that Caenorhabditis elegans embryos homozygous for the weak loss-of-function allele unc-33(e204) progress more slowly through epidermal morphogenesis, while animals homozygous for strong loss-of-function alleles exhibit more embryonic lethality. Identification of two novel missense mutations in unc-33(e572), Val476Gly and Ser731Thr, lead to computational approaches to determine the potential effects of these changes on UNC-33/CRMP structure. Molecular dynamics simulations show that for Asp389Asn and Arg502His, two other known missense mutations, local changes in protein-protein hydrogen bonding affect the stability of the protein. However, the Val476Gly/Ser731Thr combination does not alter the structure or energetics of UNC-33 drastically when compared to the wild-type protein. CONCLUSIONS These results support a novel role for UNC-33/CRMP in C. elegans epidermal development and shed light on how individual amino acid changes cause a loss-of-function in UNC-33. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Rachel Prins
- Department of Biology, Truman State University, Kirksville, MO
| | - Peter Windsor
- Department of Chemistry, Truman State University, Kirksville, MO
| | - Bill R Miller
- Department of Chemistry, Truman State University, Kirksville, MO
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9
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Ti SC. Reconstituting Microtubules: A Decades-Long Effort From Building Block Identification to the Generation of Recombinant α/β-Tubulin. Front Cell Dev Biol 2022; 10:861648. [PMID: 35573669 PMCID: PMC9096264 DOI: 10.3389/fcell.2022.861648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022] Open
Abstract
Microtubules are cytoskeletal filaments underlying the morphology and functions of all eukaryotic cells. In higher eukaryotes, the basic building blocks of these non-covalent polymers, ɑ- and β-tubulins, are encoded by expanded tubulin family genes (i.e., isotypes) at distinct loci in the genome. While ɑ/β-tubulin heterodimers have been isolated and examined for more than 50 years, how tubulin isotypes contribute to the microtubule organization and functions that support diverse cellular architectures remains a fundamental question. To address this knowledge gap, in vitro reconstitution of microtubules with purified ɑ/β-tubulin proteins has been employed for biochemical and biophysical characterization. These in vitro assays have provided mechanistic insights into the regulation of microtubule dynamics, stability, and interactions with other associated proteins. Here we survey the evolving strategies of generating purified ɑ/β-tubulin heterodimers and highlight the advances in tubulin protein biochemistry that shed light on the roles of tubulin isotypes in determining microtubule structures and properties.
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10
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Öhman T, Teppo J, Datta N, Mäkinen S, Varjosalo M, Koistinen HA. Skeletal muscle proteomes reveal downregulation of mitochondrial proteins in transition from prediabetes into type 2 diabetes. iScience 2021; 24:102712. [PMID: 34235411 PMCID: PMC8246593 DOI: 10.1016/j.isci.2021.102712] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/17/2021] [Accepted: 06/08/2021] [Indexed: 12/22/2022] Open
Abstract
Skeletal muscle insulin resistance is a central defect in the pathogenesis of type 2 diabetes (T2D). Here, we analyzed skeletal muscle proteome in 148 vastus lateralis muscle biopsies obtained from men covering all glucose tolerance phenotypes: normal, impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and T2D. Skeletal muscle proteome was analyzed by a sequential window acquisition of all theoretical mass spectra (SWATH-MS) proteomics technique. Our data indicate a downregulation in several proteins involved in mitochondrial electron transport or respiratory chain complex assembly already in IFG and IGT muscles, with most profound decreases observed in T2D. Additional phosphoproteomic analysis reveals altered phosphorylation in several signaling pathways in IFG, IGT, and T2D muscles, including those regulating glucose metabolic processes, and the structure of muscle cells. These data reveal several alterations present in skeletal muscle already in prediabetes and highlight impaired mitochondrial energy metabolism in the trajectory from prediabetes into T2D. Skeletal muscle proteome from men with all stages of glucose tolerance was analyzed Phosphoproteomics reveal altered phosphorylation in IFG, IGT, and T2D muscles OXPHOS proteins are decreased in prediabetic muscles, with most decrease in T2D
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Affiliation(s)
- Tiina Öhman
- University of Helsinki, Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, 00014 Helsinki, Finland
| | - Jaakko Teppo
- University of Helsinki, Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, 00014 Helsinki, Finland.,University of Helsinki, Drug Research Program, Faculty of Pharmacy, 00014 Helsinki, Finland
| | - Neeta Datta
- University of Helsinki, Department of Medicine, Helsinki University Hospital, Haartmaninkatu 4, PO BOX 340, 00029 HUS, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Tukholmankatu 8, 00290 Helsinki, Finland
| | - Selina Mäkinen
- University of Helsinki, Department of Medicine, Helsinki University Hospital, Haartmaninkatu 4, PO BOX 340, 00029 HUS, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Tukholmankatu 8, 00290 Helsinki, Finland
| | - Markku Varjosalo
- University of Helsinki, Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, 00014 Helsinki, Finland
| | - Heikki A Koistinen
- University of Helsinki, Department of Medicine, Helsinki University Hospital, Haartmaninkatu 4, PO BOX 340, 00029 HUS, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Tukholmankatu 8, 00290 Helsinki, Finland
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11
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Métivier M, Gallaud E, Thomas A, Pascal A, Gagné JP, Poirier GG, Chrétien D, Gibeaux R, Richard-Parpaillon L, Benaud C, Giet R. Drosophila Tubulin-Specific Chaperone E Recruits Tubulin around Chromatin to Promote Mitotic Spindle Assembly. Curr Biol 2021; 31:684-695.e6. [PMID: 33259793 DOI: 10.1016/j.cub.2020.11.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 09/29/2020] [Accepted: 11/03/2020] [Indexed: 12/31/2022]
Abstract
Proper assembly of mitotic spindles requires microtubule nucleation not only at the centrosomes but also around chromatin. In this study, we found that the Drosophila tubulin-specific chaperone dTBCE is required for the enrichment of tubulin in the nuclear space after nuclear envelope breakdown and for subsequent promotion of spindle microtubule nucleation. These events depend on the CAP-Gly motif found in dTBCE and are regulated by Ran and lamin proteins. Our data suggest that during early mitosis, dTBCE and nuclear pore proteins become enriched in the nucleus, where they interact with the Ran GTPase to promote dynamic tubulin enrichment. We propose that this novel mechanism enhances microtubule nucleation around chromatin, thereby facilitating mitotic spindle assembly.
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Affiliation(s)
- Mathieu Métivier
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Emmanuel Gallaud
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Alexandre Thomas
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Aude Pascal
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Jean-Philippe Gagné
- Centre de Recherche du Centre Hospitalier Universitaire de Québec - Pavillon CHUL, Université Laval, Québec City, QC, Canada
| | - Guy G Poirier
- Centre de Recherche du Centre Hospitalier Universitaire de Québec - Pavillon CHUL, Université Laval, Québec City, QC, Canada
| | - Denis Chrétien
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Romain Gibeaux
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Laurent Richard-Parpaillon
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Christelle Benaud
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France
| | - Régis Giet
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France.
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12
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Bertolini M, Fenzl K, Kats I, Wruck F, Tippmann F, Schmitt J, Auburger JJ, Tans S, Bukau B, Kramer G. Interactions between nascent proteins translated by adjacent ribosomes drive homomer assembly. Science 2021; 371:57-64. [PMID: 33384371 DOI: 10.1126/science.abc7151] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 10/27/2020] [Indexed: 12/13/2022]
Abstract
Accurate assembly of newly synthesized proteins into functional oligomers is crucial for cell activity. In this study, we investigated whether direct interaction of two nascent proteins, emerging from nearby ribosomes (co-co assembly), constitutes a general mechanism for oligomer formation. We used proteome-wide screening to detect nascent chain-connected ribosome pairs and identified hundreds of homomer subunits that co-co assemble in human cells. Interactions are mediated by five major domain classes, among which N-terminal coiled coils are the most prevalent. We were able to reconstitute co-co assembly of nuclear lamin in Escherichia coli, demonstrating that dimer formation is independent of dedicated assembly machineries. Co-co assembly may thus represent an efficient way to limit protein aggregation risks posed by diffusion-driven assembly routes and ensure isoform-specific homomer formation.
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Affiliation(s)
- Matilde Bertolini
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
| | - Kai Fenzl
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
| | - Ilia Kats
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
| | - Florian Wruck
- AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands
| | - Frank Tippmann
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
| | - Jaro Schmitt
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
| | - Josef Johannes Auburger
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
| | - Sander Tans
- AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands.,Department of Bionanoscience, Delft University of Technology and Kavli Institute of Nanoscience Delft, 2629HZ Delft, Netherlands
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.
| | - Günter Kramer
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.
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13
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Galderisi S, Cicaloni V, Milella MS, Millucci L, Geminiani M, Salvini L, Tinti L, Tinti C, Vieira OV, Alves LS, Crevenna AH, Spiga O, Santucci A. Homogentisic acid induces cytoskeleton and extracellular matrix alteration in alkaptonuric cartilage. J Cell Physiol 2021; 236:6011-6024. [PMID: 33469937 DOI: 10.1002/jcp.30284] [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: 05/07/2020] [Revised: 12/29/2020] [Accepted: 01/05/2021] [Indexed: 11/08/2022]
Abstract
Alkaptonuria (AKU) is an ultra-rare disease caused by the deficient activity of homogentisate 1,2-dioxygenase enzyme, leading the accumulation of homogentisic acid (HGA) in connective tissues implicating the formation of a black pigmentation called "ochronosis." Although AKU is a multisystemic disease, the most affected tissue is the articular cartilage, which during the pathology appears to be highly damaged. In this study, a model of alkaptonuric chondrocytes and cartilage was realized to investigate the role of HGA in the alteration of the extracellular matrix (ECM). The AKU tissues lost its architecture composed of collagen, proteoglycans, and all the proteins that characterize the ECM. The cause of this alteration in AKU cartilage is attributed to a degeneration of the cytoskeletal network in chondrocytes caused by the accumulation of HGA. The three cytoskeletal proteins, actin, vimentin, and tubulin, were analyzed and a modification in their amount and disposition in AKU chondrocytes model was identified. Cytoskeleton is involved in many fundamental cellular processes; therefore, the aberration in this complex network is involved in the manifestation of AKU disease.
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Affiliation(s)
- Silvia Galderisi
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy
| | - Vittoria Cicaloni
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy.,Toscana Life Sciences Foundation, Siena, Italy
| | - Maria S Milella
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy
| | - Lia Millucci
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy
| | - Michela Geminiani
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy
| | | | - Laura Tinti
- Toscana Life Sciences Foundation, Siena, Italy
| | | | - Otilia V Vieira
- NOVA Medical School, 3CEDOC, Faculdade de Ciências Médicas, Lisboa, Portugal
| | - Liliana S Alves
- NOVA Medical School, 3CEDOC, Faculdade de Ciências Médicas, Lisboa, Portugal
| | | | - Ottavia Spiga
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy
| | - Annalisa Santucci
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, Italy
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14
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Maloney SM, Hoover CA, Morejon-Lasso LV, Prosperi JR. Mechanisms of Taxane Resistance. Cancers (Basel) 2020; 12:E3323. [PMID: 33182737 PMCID: PMC7697134 DOI: 10.3390/cancers12113323] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 10/30/2020] [Accepted: 11/06/2020] [Indexed: 12/17/2022] Open
Abstract
The taxane family of chemotherapy drugs has been used to treat a variety of mostly epithelial-derived tumors and remain the first-line treatment for some cancers. Despite the improved survival time and reduction of tumor size observed in some patients, many have no response to the drugs or develop resistance over time. Taxane resistance is multi-faceted and involves multiple pathways in proliferation, apoptosis, metabolism, and the transport of foreign substances. In this review, we dive deeper into hypothesized resistance mechanisms from research during the last decade, with a focus on the cancer types that use taxanes as first-line treatment but frequently develop resistance to them. Furthermore, we will discuss current clinical inhibitors and those yet to be approved that target key pathways or proteins and aim to reverse resistance in combination with taxanes or individually. Lastly, we will highlight taxane response biomarkers, specific genes with monitored expression and correlated with response to taxanes, mentioning those currently being used and those that should be adopted. The future directions of taxanes involve more personalized approaches to treatment by tailoring drug-inhibitor combinations or alternatives depending on levels of resistance biomarkers. We hope that this review will identify gaps in knowledge surrounding taxane resistance that future research or clinical trials can overcome.
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Affiliation(s)
- Sara M. Maloney
- Harper Cancer Research Institute, South Bend, IN 46617, USA;
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, South Bend, IN 46617, USA
| | - Camden A. Hoover
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA; (C.A.H.); (L.V.M.-L.)
| | - Lorena V. Morejon-Lasso
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA; (C.A.H.); (L.V.M.-L.)
| | - Jenifer R. Prosperi
- Harper Cancer Research Institute, South Bend, IN 46617, USA;
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, South Bend, IN 46617, USA
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA; (C.A.H.); (L.V.M.-L.)
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15
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Li G, Moore JK. Microtubule dynamics at low temperature: evidence that tubulin recycling limits assembly. Mol Biol Cell 2020; 31:1154-1166. [PMID: 32213119 PMCID: PMC7353160 DOI: 10.1091/mbc.e19-11-0634] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
How temperature specifically affects microtubule dynamics and how these lead to changes in microtubule networks in cells have not been established. We investigated these questions in budding yeast, an organism found in diverse environments and therefore predicted to exhibit dynamic microtubules across a broad temperature range. We measured the dynamics of GFP-labeled microtubules in living cells and found that lowering temperature from 37°C to 10°C decreased the rates of both polymerization and depolymerization, decreased the amount of polymer assembled before catastrophes, and decreased the frequency of microtubule emergence from nucleation sites. Lowering to 4°C caused rapid loss of almost all microtubule polymer. We provide evidence that these effects on microtubule dynamics may be explained in part by changes in the cofactor-dependent conformational dynamics of tubulin proteins. Ablation of tubulin-binding cofactors (TBCs) further sensitizes cells and their microtubules to low temperatures, and we highlight a specific role for TBCB/Alf1 in microtubule maintenance at low temperatures. Finally, we show that inhibiting the maturation cycle of tubulin by using a point mutant in β-tubulin confers hyperstable microtubules at low temperatures and rescues the requirement for TBCB/Alf1 in maintaining microtubule polymer at low temperatures. Together, these results reveal an unappreciated step in the tubulin cycle.
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Affiliation(s)
- Gabriella Li
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
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16
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Protective effect of calpeptin on acrylamide-induced microtubule injury in sciatic nerve. Toxicology 2018; 409:103-111. [DOI: 10.1016/j.tox.2018.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 07/12/2018] [Accepted: 08/04/2018] [Indexed: 12/16/2022]
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17
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Parker AL, Teo WS, Pandzic E, Vicente JJ, McCarroll JA, Wordeman L, Kavallaris M. β-tubulin carboxy-terminal tails exhibit isotype-specific effects on microtubule dynamics in human gene-edited cells. Life Sci Alliance 2018; 1. [PMID: 30079401 PMCID: PMC6070155 DOI: 10.26508/lsa.201800059] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
This study used human gene-edited cell models and image analysis to reveal that the tubulin C-terminal tails specifically regulate the dynamics of individual microtubules and coordinate microtubule behavior across the cell. Microtubules are highly dynamic structures that play an integral role in fundamental cellular functions. Different α- and β-tubulin isotypes are thought to confer unique dynamic properties to microtubules. The tubulin isotypes have highly conserved structures, differing mainly in their carboxy-terminal (C-terminal) tail sequences. However, little is known about the importance of the C-terminal tail in regulating and coordinating microtubule dynamics. We developed syngeneic human cell models using gene editing to precisely modify the β-tubulin C-terminal tail region while preserving the endogenous microtubule network. Fluorescent microscopy of live cells, coupled with advanced image analysis, revealed that the β-tubulin C-terminal tails differentially coordinate the collective and individual dynamic behavior of microtubules by affecting microtubule growth rates and explorative microtubule assembly in an isotype-specific manner. Furthermore, βI- and βIII-tubulin C-terminal tails differentially regulate the sensitivity of microtubules to tubulin-binding agents and the microtubule depolymerizing protein mitotic centromere-associated kinesin. The sequence of the β-tubulin tail encodes regulatory information that instructs and coordinates microtubule dynamics, thereby fine-tuning microtubule dynamics to support cellular functions.
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Affiliation(s)
- Amelia L Parker
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, NSW, Australia 2031.,Australian Centre for NanoMedicine and ARC Centre of Excellence for Convergent BioNano Science and Technology, UNSW Sydney, NSW, Australia 2052.,School of Women's and Children's Health, Faculty of Medicine, UNSW Sydney, NSW, Australia 2052
| | - Wee Siang Teo
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, NSW, Australia 2031.,Australian Centre for NanoMedicine and ARC Centre of Excellence for Convergent BioNano Science and Technology, UNSW Sydney, NSW, Australia 2052.,School of Women's and Children's Health, Faculty of Medicine, UNSW Sydney, NSW, Australia 2052
| | - Elvis Pandzic
- Biomedical Imaging Facility, Mark Wainwright Analytical Centre, Lowy Cancer Research Centre, UNSW Sydney, NSW, Australia 2052
| | - Juan Jesus Vicente
- Department of Physiology and Biophysics, School of Medicine, University of Washington, Seattle, WA, USA 98195-7290
| | - Joshua A McCarroll
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, NSW, Australia 2031.,Australian Centre for NanoMedicine and ARC Centre of Excellence for Convergent BioNano Science and Technology, UNSW Sydney, NSW, Australia 2052.,School of Women's and Children's Health, Faculty of Medicine, UNSW Sydney, NSW, Australia 2052
| | - Linda Wordeman
- Department of Physiology and Biophysics, School of Medicine, University of Washington, Seattle, WA, USA 98195-7290
| | - Maria Kavallaris
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, NSW, Australia 2031.,Australian Centre for NanoMedicine and ARC Centre of Excellence for Convergent BioNano Science and Technology, UNSW Sydney, NSW, Australia 2052.,School of Women's and Children's Health, Faculty of Medicine, UNSW Sydney, NSW, Australia 2052
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18
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Abstract
During the process of neurogenesis, the stem cell committed to the neuronal cell fate starts a series of molecular and morphological changes. The understanding of the physio-pathology of mechanisms controlling the molecular and morphological changes occurring during neuronal differentiation is fundamental to the development of effective therapies for many neurologic diseases. Unfortunately, our knowledge of the biological events occurring in the cell during neuronal differentiation is still poor. In this study, we focus preliminarily on the relevance of the cytoskeletal rearrangements, which earlier drive the morphology of the neuronal precursors, and later the migrating/mature neurons. In fact, neuritogenesis, neurite branching, outgrowth and retraction are seminal to the development of a fully functional nervous system. With this in mind, we highlight the importance of iPSC technology to study the processes of cytoskeletal-driven morphological changes during neuronal differentiation.
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19
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Francis JW, Goswami D, Novick SJ, Pascal BD, Weikum ER, Ortlund EA, Griffin PR, Kahn RA. Nucleotide Binding to ARL2 in the TBCD∙ARL2∙β-Tubulin Complex Drives Conformational Changes in β-Tubulin. J Mol Biol 2017; 429:3696-3716. [PMID: 28970104 DOI: 10.1016/j.jmb.2017.09.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 08/31/2017] [Accepted: 09/26/2017] [Indexed: 11/25/2022]
Abstract
Microtubules are highly dynamic tubulin polymers that are required for a variety of cellular functions. Despite the importance of a cellular population of tubulin dimers, we have incomplete information about the mechanisms involved in the biogenesis of αβ-tubulin heterodimers. In addition to prefoldin and the TCP-1 Ring Complex, five tubulin-specific chaperones, termed cofactors A-E (TBCA-E), and GTP are required for the folding of α- and β-tubulin subunits and assembly into heterodimers. We recently described the purification of a novel trimer, TBCD•ARL2•β-tubulin. Here, we employed hydrogen/deuterium exchange coupled with mass spectrometry to explore the dynamics of each of the proteins in the trimer. Addition of guanine nucleotides resulted in changes in the solvent accessibility of regions of each protein that led to predictions about each's role in tubulin folding. Initial testing of that model confirmed that it is ARL2, and not β-tubulin, that exchanges GTP in the trimer. Comparisons of the dynamics of ARL2 monomer to ARL2 in the trimer suggested that its protein interactions were comparable to those of a canonical GTPase with an effector. This was supported by the use of nucleotide-binding assays that revealed an increase in the affinity for GTP by ARL2 in the trimer. We conclude that the TBCD•ARL2•β-tubulin complex represents a functional intermediate in the β-tubulin folding pathway whose activity is regulated by the cycling of nucleotides on ARL2. The co-purification of guanine nucleotide on the β-tubulin in the trimer is also shown, with implications to modeling the pathway.
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Affiliation(s)
- Joshua W Francis
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Devrishi Goswami
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, United States
| | - Scott J Novick
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, United States
| | - Bruce D Pascal
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, United States
| | - Emily R Weikum
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Eric A Ortlund
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Patrick R Griffin
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, United States
| | - Richard A Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, United States.
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20
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Al-Bassam J. Revisiting the tubulin cofactors and Arl2 in the regulation of soluble αβ-tubulin pools and their effect on microtubule dynamics. Mol Biol Cell 2017; 28:359-363. [PMID: 28137948 PMCID: PMC5341719 DOI: 10.1091/mbc.e15-10-0694] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 11/22/2016] [Accepted: 12/01/2016] [Indexed: 12/12/2022] Open
Abstract
Soluble αβ-tubulin heterodimers are maintained at high concentration inside eukaryotic cells, forming pools that fundamentally drive microtubule dynamics. Five conserved tubulin cofactors and ADP ribosylation factor-like 2 regulate the biogenesis and degradation of αβ-tubulins to maintain concentrated soluble pools. Here I describe a revised model for the function of three tubulin cofactors and Arl2 as a multisubunit GTP-hydrolyzing catalytic chaperone that cycles to promote αβ-tubulin biogenesis and degradation. This model helps explain old and new data indicating these activities enhance microtubule dynamics in vivo via repair or removal of αβ-tubulins from the soluble pools.
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Affiliation(s)
- Jawdat Al-Bassam
- Molecular Cellular Biology, University of California, Davis, Davis, CA 95616
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21
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HILI destabilizes microtubules by suppressing phosphorylation and Gigaxonin-mediated degradation of TBCB. Sci Rep 2017; 7:46376. [PMID: 28393858 PMCID: PMC5385498 DOI: 10.1038/srep46376] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/15/2017] [Indexed: 02/05/2023] Open
Abstract
Human PIWIL2, aka HILI, is a member of PIWI protein family and overexpresses in various tumors. However, the underlying mechanisms of HILI in tumorigenesis remain largely unknown. TBCB has a critical role in regulating microtubule dynamics and is overexpressed in many cancers. Here we report that HILI inhibits Gigaxonin-mediated TBCB ubiquitination and degradation by interacting with TBCB, promoting the binding between HSP90 and TBCB, and suppressing the interaction between Gigaxonin and TBCB. Meanwhile, HILI can also reduce phosphorylation level of TBCB induced by PAK1. Our results showed that HILI suppresses microtubule polymerization and promotes cell proliferation, migration and invasion via TBCB for the first time, revealing a novel mechanism for HILI in tumorigenesis.
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22
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Veitia RA, Govindaraju DR, Bottani S, Birchler JA. Aging: Somatic Mutations, Epigenetic Drift and Gene Dosage Imbalance. Trends Cell Biol 2017; 27:299-310. [DOI: 10.1016/j.tcb.2016.11.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/09/2016] [Accepted: 11/10/2016] [Indexed: 10/20/2022]
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23
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Breuss MW, Leca I, Gstrein T, Hansen AH, Keays DA. Tubulins and brain development - The origins of functional specification. Mol Cell Neurosci 2017; 84:58-67. [PMID: 28347630 DOI: 10.1016/j.mcn.2017.03.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Revised: 02/28/2017] [Accepted: 03/05/2017] [Indexed: 10/19/2022] Open
Abstract
The development of the vertebrate central nervous system is reliant on a complex cascade of biological processes that include mitotic division, relocation of migrating neurons, and the extension of dendritic and axonal processes. Each of these cellular events requires the diverse functional repertoire of the microtubule cytoskeleton for the generation of forces, assembly of macromolecular complexes and transport of molecules and organelles. The tubulins are a multi-gene family that encode for the constituents of microtubules, and have been implicated in a spectrum of neurological disorders. Evidence is building that different tubulins tune the functional properties of the microtubule cytoskeleton dependent on the cell type, developmental profile and subcellular localisation. Here we review of the origins of the functional specification of the tubulin gene family in the developing brain at a transcriptional, translational, and post-transcriptional level. We remind the reader that tubulins are not just loading controls for your average Western blot.
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Affiliation(s)
- Martin W Breuss
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ines Leca
- Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Dr Bohr-Gasse 7, Vienna 1030, Austria
| | - Thomas Gstrein
- Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Dr Bohr-Gasse 7, Vienna 1030, Austria
| | - Andi H Hansen
- Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Dr Bohr-Gasse 7, Vienna 1030, Austria; Institute of Science and Technology Austria, Klosterneuburg 3400, Austria
| | - David A Keays
- Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Dr Bohr-Gasse 7, Vienna 1030, Austria.
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24
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McMurray MA. Coupling de novo protein folding with subunit exchange into pre-formed oligomeric protein complexes: the 'heritable template' hypothesis. Biomol Concepts 2017; 7:271-281. [PMID: 27875316 DOI: 10.1515/bmc-2016-0023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/11/2016] [Indexed: 11/15/2022] Open
Abstract
Despite remarkable advances in synthetic biology, the fact remains that it takes a living cell to make a new living cell. The information encoded in the genome is necessary to direct assembly of all cellular components, but it may not be sufficient. Some components (e.g. mitochondria) cannot be synthesized de novo, and instead require pre-existing templates, creating a fundamental continuity of life: if the template information is ever lost, the genomic code cannot suffice to ensure proper biogenesis. One type of information only incompletely encoded in the genome is the structures of macromolecular assemblies, which emerge from the conformations of the constituent molecules coupled with the ways in which these molecules interact. For many, if not most proteins, gene sequence is not the sole determinant of native conformation, particularly in the crowded cellular milieu. A partial solution to this problem lies in the functions of molecular chaperones, encoded by nearly all cellular genomes. Chaperones effectively restrict the ensemble of conformations sampled by polypeptides, promoting the acquisition of native, functional forms, but multiple proteins have evolved ways to achieve chaperone independence, perhaps by coupling folding with higher-order assembly. Here, I propose the existence of another solution: a novel mechanism of de novo folding in which the folding of specific proteins is templated by pre-folded molecules of a partner protein whose own folding also required similar templating. This hypothesis challenges prevailing paradigms by predicting that, in order to achieve a functional fold, some non-prion proteins require a seed passed down through generations.
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25
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Francis JW, Newman LE, Cunningham LA, Kahn RA. A Trimer Consisting of the Tubulin-specific Chaperone D (TBCD), Regulatory GTPase ARL2, and β-Tubulin Is Required for Maintaining the Microtubule Network. J Biol Chem 2017; 292:4336-4349. [PMID: 28126905 DOI: 10.1074/jbc.m116.770909] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/24/2017] [Indexed: 11/06/2022] Open
Abstract
Microtubule dynamics involves the polymerization and depolymerization of tubulin dimers and is an essential and highly regulated process required for cell viability, architecture, and division. The regulation of the microtubule network also depends on the maintenance of a pool of αβ-tubulin heterodimers. These dimers are the end result of complex folding and assembly events, requiring the TCP1 Ring Complex (TriC or CCT) chaperonin and five tubulin-specific chaperones, tubulin binding cofactors A-E (TBCA-TBCE). However, models of the actions of these chaperones are incomplete or inconsistent. We previously purified TBCD from bovine tissues and showed that it tightly binds the small GTPase ARL2 but appears to be inactive. Here, in an effort to identify the functional form of TBCD and using non-denaturing gels and immunoblotting, we analyzed lysates from a number of mouse tissues and cell lines to identify the quaternary state(s) of TBCD and ARL2. We found that both proteins co-migrated in native gels in a complex of ∼200 kDa that also contained β-tubulin. Using human embryonic kidney cells enabled the purification of the TBCD·ARL2·β-tubulin trimer found in cell and tissue lysates as well as two other novel TBCD complexes. Characterization of ARL2 point mutants that disrupt binding to TBCD suggested that the ARL2-TBCD interaction is critical for proper maintenance of microtubule densities in cells. We conclude that the TBCD·ARL2·β-tubulin trimer represents a functional complex whose activity is fundamental to microtubule dynamics.
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Affiliation(s)
- Joshua W Francis
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Laura E Newman
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Leslie A Cunningham
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Richard A Kahn
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
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26
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Pode-Shakked B, Barash H, Ziv L, Gripp KW, Flex E, Barel O, Carvalho KS, Scavina M, Chillemi G, Niceta M, Eyal E, Kol N, Ben-Zeev B, Bar-Yosef O, Marek-Yagel D, Bertini E, Duker AL, Anikster Y, Tartaglia M, Raas-Rothschild A. Microcephaly, intractable seizures and developmental delay caused by biallelic variants in TBCD: further delineation of a new chaperone-mediated tubulinopathy. Clin Genet 2016; 91:725-738. [PMID: 27807845 DOI: 10.1111/cge.12914] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 10/26/2016] [Accepted: 10/28/2016] [Indexed: 12/19/2022]
Abstract
Microtubule dynamics play a crucial role in neuronal development and function, and several neurodevelopmental disorders have been linked to mutations in genes encoding tubulins and functionally related proteins. Most recently, variants in the tubulin cofactor D (TBCD) gene, which encodes one of the five co-chaperones required for assembly and disassembly of α/β-tubulin heterodimer, were reported to underlie a recessive neurodevelopmental/neurodegenerative disorder. We report on five patients from three unrelated families, who presented with microcephaly, intellectual disability, intractable seizures, optic nerve pallor/atrophy, and cortical atrophy with delayed myelination and thinned corpus callosum on brain imaging. Exome sequencing allowed the identification of biallelic variants in TBCD segregating with the disease in the three families. TBCD protein level was significantly reduced in cultured fibroblasts from one patient, supporting defective TBCD function as the event underlying the disorder. Such reduced expression was associated with accelerated microtubule re-polymerization. Morpholino-mediated TBCD knockdown in zebrafish recapitulated several key pathological features of the human disease, and TBCD overexpression in the same model confirmed previous studies documenting an obligate dependency on proper TBCD levels during development. Our findings confirm the link between inactivating TBCD variants and this newly described chaperone-associated tubulinopathy, and provide insights into the phenotype of this disorder.
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Affiliation(s)
- B Pode-Shakked
- The Institute for Rare Diseases, The Danek Gertner Institute of Human Genetics, Sheba Medical Center, Tel-Hashomer, Israel.,Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.,The Dr Pinchas Borenstein Talpiot Medical Leadership Program, Sheba Medical Center, Tel-Hashomer, Israel
| | - H Barash
- The Institute for Rare Diseases, The Danek Gertner Institute of Human Genetics, Sheba Medical Center, Tel-Hashomer, Israel
| | - L Ziv
- Sheba Cancer Research Center, Sheba Medical Center, Tel-Hashomer, Israel
| | - K W Gripp
- Division of Medical Genetics, A.I. duPont Hospital for Children, Wilmington, DE, USA
| | - E Flex
- Department of Hematology, Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
| | - O Barel
- Sheba Cancer Research Center, Sheba Medical Center, Tel-Hashomer, Israel
| | - K S Carvalho
- Section of Pediatric Neurology, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, PA, USA
| | - M Scavina
- Division of Pediatric Neurology, A.I. duPont Hospital for Children, Wilmington, DE, USA
| | - G Chillemi
- SCAI-Super Computing Applications and Innovation Department, CINECA, Rome, Italy
| | - M Niceta
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - E Eyal
- Sheba Cancer Research Center, Sheba Medical Center, Tel-Hashomer, Israel
| | - N Kol
- Sheba Cancer Research Center, Sheba Medical Center, Tel-Hashomer, Israel
| | - B Ben-Zeev
- Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.,Pediatric Neurology Unit, Edmond and Lily Safra Children's Hospital, Tel-Hashomer, Israel
| | - O Bar-Yosef
- Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.,Pediatric Neurology Unit, Edmond and Lily Safra Children's Hospital, Tel-Hashomer, Israel
| | - D Marek-Yagel
- Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.,Metabolic Disease Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel
| | - E Bertini
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - A L Duker
- Division of Medical Genetics, A.I. duPont Hospital for Children, Wilmington, DE, USA
| | - Y Anikster
- Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.,Metabolic Disease Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel
| | - M Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - A Raas-Rothschild
- The Institute for Rare Diseases, The Danek Gertner Institute of Human Genetics, Sheba Medical Center, Tel-Hashomer, Israel.,Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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27
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Edvardson S, Tian G, Cullen H, Vanyai H, Ngo L, Bhat S, Aran A, Daana M, Da’amseh N, Abu-Libdeh B, Cowan NJ, Heng JIT, Elpeleg O. Infantile neurodegenerative disorder associated with mutations in TBCD, an essential gene in the tubulin heterodimer assembly pathway. Hum Mol Genet 2016; 25:4635-4648. [PMID: 28158450 PMCID: PMC6459059 DOI: 10.1093/hmg/ddw292] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 08/05/2016] [Accepted: 08/25/2016] [Indexed: 02/07/2023] Open
Abstract
Mutation in a growing spectrum of genes is known to either cause or contribute to primary or secondary microcephaly. In primary microcephaly the genetic determinants frequently involve mutations that contribute to or modulate the microtubule cytoskeleton by causing perturbations of neuronal proliferation and migration. Here we describe four patients from two unrelated families each with an infantile neurodegenerative disorder characterized by loss of developmental milestones at 9–24 months of age followed by seizures, dystonia and acquired microcephaly. The patients harboured homozygous missense mutations (A475T and A586V) in TBCD, a gene encoding one of five tubulin-specific chaperones (termed TBCA-E) that function in concert as a nanomachine required for the de novo assembly of the α/β tubulin heterodimer. The latter is the subunit from which microtubule polymers are assembled. We found a reduced intracellular abundance of TBCD in patient fibroblasts to about 10% (in the case of A475T) or 40% (in the case of A586V) compared to age-matched wild type controls. Functional analyses of the mutant proteins revealed a partially compromised ability to participate in the heterodimer assembly pathway. We show via in utero shRNA-mediated suppression that a balanced supply of tbcd is critical for cortical cell proliferation and radial migration in the developing mouse brain. We conclude that TBCD is a novel functional contributor to the mammalian cerebral cortex development, and that the pathological mechanism resulting from the mutations we describe is likely to involve compromised interactions with one or more TBCD-interacting effectors that influence the dynamics and behaviour of the neuronal cytoskeleton.
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Affiliation(s)
- Shimon Edvardson
- Monique and Jacques Roboh Department of Genetic Research, Hadassah, Hebrew University Medical Center Jerusalem, Jerusalem, Israel
- Neuropediatric Unit, Hadassah Hebrew University Medical Center, Jerusalem, Israel
| | - Guoling Tian
- Department of Biochemistry & Molecular Pharmacology, NYU Langone Medical Center, New York, NY, USA
| | - Hayley Cullen
- The Harry Perkins Institute of Medical Research, QEII Medical Centre and Centre for Medical Research, the University of Western Australia, Nedlands, Western Australia, Australia
| | - Hannah Vanyai
- The Harry Perkins Institute of Medical Research, QEII Medical Centre and Centre for Medical Research, the University of Western Australia, Nedlands, Western Australia, Australia
| | - Linh Ngo
- The Harry Perkins Institute of Medical Research, QEII Medical Centre and Centre for Medical Research, the University of Western Australia, Nedlands, Western Australia, Australia
| | - Saiuj Bhat
- The Harry Perkins Institute of Medical Research, QEII Medical Centre and Centre for Medical Research, the University of Western Australia, Nedlands, Western Australia, Australia
| | - Adi Aran
- Neuropediatric Unit, Shaare Zedek Medical Center; Hebrew University-Hadassah School of Medicine, Jerusalem, Israel
| | - Muhannad Daana
- Neuropediatric Unit, Hadassah Hebrew University Medical Center, Jerusalem, Israel
| | - Naderah Da’amseh
- Department of Pediatrics and Genetics, Makassed Hospital, Al-Quds Medical School, Jerusalem
| | - Bassam Abu-Libdeh
- Department of Pediatrics and Genetics, Makassed Hospital, Al-Quds Medical School, Jerusalem
| | - Nicholas J. Cowan
- Department of Biochemistry & Molecular Pharmacology, NYU Langone Medical Center, New York, NY, USA
| | - Julian Ik-Tsen Heng
- The Harry Perkins Institute of Medical Research, QEII Medical Centre and Centre for Medical Research, the University of Western Australia, Nedlands, Western Australia, Australia
| | - Orly Elpeleg
- Monique and Jacques Roboh Department of Genetic Research, Hadassah, Hebrew University Medical Center Jerusalem, Jerusalem, Israel
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28
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Miyake N, Fukai R, Ohba C, Chihara T, Miura M, Shimizu H, Kakita A, Imagawa E, Shiina M, Ogata K, Okuno-Yuguchi J, Fueki N, Ogiso Y, Suzumura H, Watabe Y, Imataka G, Leong HY, Fattal-Valevski A, Kramer U, Miyatake S, Kato M, Okamoto N, Sato Y, Mitsuhashi S, Nishino I, Kaneko N, Nishiyama A, Tamura T, Mizuguchi T, Nakashima M, Tanaka F, Saitsu H, Matsumoto N. Biallelic TBCD Mutations Cause Early-Onset Neurodegenerative Encephalopathy. Am J Hum Genet 2016; 99:950-961. [PMID: 27666374 DOI: 10.1016/j.ajhg.2016.08.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/09/2016] [Indexed: 01/01/2023] Open
Abstract
We describe four families with affected siblings showing unique clinical features: early-onset (before 1 year of age) progressive diffuse brain atrophy with regression, postnatal microcephaly, postnatal growth retardation, muscle weakness/atrophy, and respiratory failure. By whole-exome sequencing, we identified biallelic TBCD mutations in eight affected individuals from the four families. TBCD encodes TBCD (tubulin folding co-factor D), which is one of five tubulin-specific chaperones playing a pivotal role in microtubule assembly in all cells. A total of seven mutations were found: five missense mutations, one nonsense, and one splice site mutation resulting in a frameshift. In vitro cell experiments revealed the impaired binding between most mutant TBCD proteins and ARL2, TBCE, and β-tubulin. The in vivo experiments using olfactory projection neurons in Drosophila melanogaster indicated that the TBCD mutations caused loss of function. The wide range of clinical severity seen in this neurodegenerative encephalopathy may result from the residual function of mutant TBCD proteins. Furthermore, the autopsied brain from one deceased individual showed characteristic neurodegenerative findings: cactus and somatic sprout formations in the residual Purkinje cells in the cerebellum, which are also seen in some diseases associated with mitochondrial impairment. Defects of microtubule formation caused by TBCD mutations may underlie the pathomechanism of this neurodegenerative encephalopathy.
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29
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Francis JW, Turn RE, Newman LE, Schiavon C, Kahn RA. Higher order signaling: ARL2 as regulator of both mitochondrial fusion and microtubule dynamics allows integration of 2 essential cell functions. Small GTPases 2016; 7:188-196. [PMID: 27400436 PMCID: PMC5129891 DOI: 10.1080/21541248.2016.1211069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 07/05/2016] [Accepted: 07/06/2016] [Indexed: 10/21/2022] Open
Abstract
ARL2 is among the most highly conserved proteins, predicted to be present in the last eukaryotic common ancestor, and ubiquitously expressed. Genetic screens in multiple model organisms identified ARL2, and its cytosolic binding partner cofactor D (TBCD), as important in tubulin folding and microtubule dynamics. Both ARL2 and TBCD also localize to centrosomes, making it difficult to dissect these effects. A growing body of evidence also has found roles for ARL2 inside mitochondria, as a regulator of mitochondrial fusion. Other studies have revealed roles for ARL2, in concert with its closest paralog ARL3, in the traffic of farnesylated cargos between membranes and specifically to cilia and photoreceptor cells. Details of each of these signaling processes continue to emerge. We summarize those data here and speculate about the potential for cross-talk or coordination of cell regulation, termed higher order signaling, based upon the use of a common GTPase in disparate cell functions.
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Affiliation(s)
- Joshua W. Francis
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Rachel E. Turn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Laura E. Newman
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Cara Schiavon
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
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30
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Chen K, Koe CT, Xing ZB, Tian X, Rossi F, Wang C, Tang Q, Zong W, Hong WJ, Taneja R, Yu F, Gonzalez C, Wu C, Endow S, Wang H. Arl2- and Msps-dependent microtubule growth governs asymmetric division. J Cell Biol 2016; 212:661-76. [PMID: 26953351 PMCID: PMC4792071 DOI: 10.1083/jcb.201503047] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 02/10/2016] [Indexed: 12/18/2022] Open
Abstract
Drosophila Arl2 governs neuroblast asymmetric cell division through regulation of microtubule growth and localization of Msps to centrosomes. Asymmetric division of neural stem cells is a fundamental strategy to balance their self-renewal and differentiation. It is long thought that microtubules are not essential for cell polarity in asymmetrically dividing Drosophila melanogaster neuroblasts (NBs; neural stem cells). Here, we show that Drosophila ADP ribosylation factor like-2 (Arl2) and Msps, a known microtubule-binding protein, control cell polarity and spindle orientation of NBs. Upon arl2 RNA intereference, Arl2-GDP expression, or arl2 deletions, microtubule abnormalities and asymmetric division defects were observed. Conversely, overactivation of Arl2 leads to microtubule overgrowth and depletion of NBs. Arl2 regulates microtubule growth and asymmetric division through localizing Msps to the centrosomes in NBs. Moreover, Arl2 regulates dynein function and in turn centrosomal localization of D-TACC and Msps. Arl2 physically associates with tubulin cofactors C, D, and E. Arl2 functions together with tubulin-binding cofactor D to control microtubule growth, Msps localization, and NB self-renewal. Therefore, Arl2- and Msps-dependent microtubule growth is a new paradigm regulating asymmetric division of neural stem cells.
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Affiliation(s)
- Keng Chen
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857 National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456
| | - Chwee Tat Koe
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857 National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456
| | - Zhanyuan Benny Xing
- Department of Cell Biology, Duke University, Duke University Medical Center, Durham, NC 27710
| | - Xiaolin Tian
- Neuroscience Center of Excellence, Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, LA 70112
| | - Fabrizio Rossi
- Institute for Research in Biomedicine Barcelona, 08028 Barcelona, Spain
| | - Cheng Wang
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857
| | - Quan Tang
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117604
| | - Wenhui Zong
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117604
| | - Wan Jin Hong
- Institute of Molecular and Cell Biology, Singapore 138673
| | - Reshma Taneja
- National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597
| | - Fengwei Yu
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857 National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117604
| | - Cayetano Gonzalez
- Institute for Research in Biomedicine Barcelona, 08028 Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
| | - Chunlai Wu
- Neuroscience Center of Excellence, Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, LA 70112
| | - Sharyn Endow
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857 Department of Cell Biology, Duke University, Duke University Medical Center, Durham, NC 27710
| | - Hongyan Wang
- Neuroscience and Behavioral Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore 169857 National University of Singapore Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597
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31
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Laquerriere A, Gonzales M, Saillour Y, Cavallin M, Joyē N, Quēlin C, Bidat L, Dommergues M, Plessis G, Encha-Razavi F, Chelly J, Bahi-Buisson N, Poirier K. De novo TUBB2B mutation causes fetal akinesia deformation sequence with microlissencephaly: An unusual presentation of tubulinopathy. Eur J Med Genet 2015; 59:249-56. [PMID: 26732629 DOI: 10.1016/j.ejmg.2015.12.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 11/26/2015] [Accepted: 12/20/2015] [Indexed: 11/19/2022]
Abstract
Tubulinopathies are increasingly emerging major causes underlying complex cerebral malformations, particularly in case of microlissencephaly often associated with hypoplastic or absent corticospinal tracts. Fetal akinesia deformation sequence (FADS) refers to a clinically and genetically heterogeneous group of disorders with congenital malformations related to impaired fetal movement. We report on an early foetal case with FADS and microlissencephaly due to TUBB2B mutation. Neuropathological examination disclosed virtually absent cortical lamination, foci of neuronal overmigration into the leptomeningeal spaces, corpus callosum agenesis, cerebellar and brainstem hypoplasia and extremely severe hypoplasia of the spinal cord with no anterior and posterior horns and almost no motoneurons. At the cellular level, the p.Cys239Phe TUBB2B mutant leads to tubulin heterodimerization impairment, decreased ability to incorporate into the cytoskeleton, microtubule dynamics alteration, with an accelerated rate of depolymerization. To our knowledge, this is the first case of microlissencephaly to be reported presenting with a so severe and early form of FADS, highlighting the importance of tubulin mutation screening in the context of FADS with microlissencephaly.
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Affiliation(s)
- Annie Laquerriere
- Pathology Laboratory, Rouen University Hospital, France; Region-Inserm Team NeoVasc ERI28, Laboratory of Microvascular Endothelium and Neonate Brain Lesions, Institute of Research Innovation in Biomedecine, Normandy University, Rouen, France
| | - Marie Gonzales
- Department of Medical Genetics, Armand Trousseau Hospital, APHP, Paris, France; Sorbonne Universities, UPMC, Paris, France
| | - Yoann Saillour
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR8104, Paris, France; Paris Descartes - Sorbonne Paris Cité University, Imagine Institute, Paris, France
| | - Mara Cavallin
- Paris Descartes - Sorbonne Paris Cité University, Imagine Institute, Paris, France; Pediatric Neurology, Necker Enfants Malades University Hospital, Paris, France; INSERM UMR-1163, Embryology and Genetics of Congenital Malformation Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, France
| | - Nicole Joyē
- Department of Medical Genetics, Armand Trousseau Hospital, APHP, Paris, France; Sorbonne Universities, UPMC, Paris, France
| | - Chloé Quēlin
- Department of Clinical Genetics, South University Hospital, Rennes, France
| | - Laurent Bidat
- Department of Prenatal Diagnosis, Department of Obstetrics and Gynecology, René Dubos Hospital, Pontoise, France
| | - Marc Dommergues
- Sorbonne Universities, UPMC, Paris, France; Department of Obstetrics and Gynecology, Groupe Hospitalier Pitié Salpêtrière, APHP, Paris, France
| | - Ghislaine Plessis
- Department of Genetics, Clinical Genetics, Caen University Hospital, Caen, France
| | - Ferechte Encha-Razavi
- Paris Descartes - Sorbonne Paris Cité University, Imagine Institute, Paris, France; Pediatric Neurology, Necker Enfants Malades University Hospital, Paris, France; Département de Génétique, Necker-Enfants Malades University Hospital, Paris, France
| | - Jamel Chelly
- Pôle de biologie, Hôpitaux Universitaires de Strasbourg, Strasbourg, France; Institut de Génétique et Biologie Moléculaire et Cellulaire - IGBMC, INSERM, CNRS, Université de Strasbourg, Strasbourg, France
| | - Nadia Bahi-Buisson
- Paris Descartes - Sorbonne Paris Cité University, Imagine Institute, Paris, France; Pediatric Neurology, Necker Enfants Malades University Hospital, Paris, France; INSERM UMR-1163, Embryology and Genetics of Congenital Malformation Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, France.
| | - Karine Poirier
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR8104, Paris, France; Paris Descartes - Sorbonne Paris Cité University, Imagine Institute, Paris, France
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32
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Haase G, Rabouille C. Golgi Fragmentation in ALS Motor Neurons. New Mechanisms Targeting Microtubules, Tethers, and Transport Vesicles. Front Neurosci 2015; 9:448. [PMID: 26696811 PMCID: PMC4672084 DOI: 10.3389/fnins.2015.00448] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/13/2015] [Indexed: 12/12/2022] Open
Abstract
Pathological alterations of the Golgi apparatus, such as its fragmentation represent an early pre-clinical feature of many neurodegenerative diseases and have been widely studied in the motor neuron disease amyotrophic lateral sclerosis (ALS). Yet, the underlying molecular mechanisms have remained cryptic. In principle, Golgi fragmentation may result from defects in three major classes of proteins: structural Golgi proteins, cytoskeletal proteins and molecular motors, as well as proteins mediating transport to and through the Golgi. Here, we present the different mechanisms that may underlie Golgi fragmentation in animal and cellular models of ALS linked to mutations in SOD1, TARDBP (TDP-43), VAPB, and C9Orf72 and we propose a novel one based on findings in progressive motor neuronopathy (pmn) mice. These mice are mutated in the TBCE gene encoding the cis-Golgi localized tubulin-binding cofactor E, one of five chaperones that assist in tubulin folding and microtubule polymerization. Loss of TBCE leads to alterations in Golgi microtubules, which in turn impedes on the maintenance of the Golgi architecture. This is due to down-regulation of COPI coat components, dispersion of Golgi tethers and strong accumulation of ER-Golgi SNAREs. These effects are partially rescued by the GTPase ARF1 through recruitment of TBCE to the Golgi. We hypothesize that defects in COPI vesicles, microtubules and their interaction may also underlie Golgi fragmentation in human ALS linked to other mutations, spinal muscular atrophy (SMA), and related motor neuron diseases. We also discuss the functional relevance of pathological Golgi alterations, in particular their potential causative, contributory, or compensatory role in the degeneration of motor neuron cell bodies, axons and synapses.
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Affiliation(s)
- Georg Haase
- Centre National de la Recherche Scientifique and Aix-Marseille Université UMR 7289, Institut de Neurosciences de la Timone Marseille, France
| | - Catherine Rabouille
- The Department of Cell Biology, Hubrecht Institute of the Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht Utrecht, Netherlands
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33
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Gartz Hanson M, Aiken J, Sietsema DV, Sept D, Bates EA, Niswander L, Moore JK. Novel α-tubulin mutation disrupts neural development and tubulin proteostasis. Dev Biol 2015; 409:406-19. [PMID: 26658218 DOI: 10.1016/j.ydbio.2015.11.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/10/2015] [Accepted: 11/27/2015] [Indexed: 10/22/2022]
Abstract
Mutations in the microtubule cytoskeleton are linked to cognitive and locomotor defects during development, and neurodegeneration in adults. How these mutations impact microtubules, and how this alters function at the level of neurons is an important area of investigation. Using a forward genetic screen in mice, we identified a missense mutation in Tuba1a α-tubulin that disrupts cortical and motor neuron development. Homozygous mutant mice exhibit cortical dysgenesis reminiscent of human tubulinopathies. Motor neurons fail to innervate target muscles in the limbs and show synapse defects at proximal targets. To directly examine effects on tubulin function, we created analogous mutations in the α-tubulin isotypes in budding yeast. These mutations sensitize yeast cells to microtubule stresses including depolymerizing drugs and low temperatures. Furthermore, we find that mutant α-tubulin is depleted from the cell lysate and from microtubules, thereby altering ratios of α-tubulin isotypes. Tubulin-binding cofactors suppress the effects of the mutation, indicating an important role for these cofactors in regulating the quality of the α-tubulin pool. Together, our results give new insights into the functions of Tuba1a, mechanisms for regulating tubulin proteostasis, and how compromising these may lead to neural defects.
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Affiliation(s)
- M Gartz Hanson
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Jayne Aiken
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Daniel V Sietsema
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - David Sept
- Department of Biomedical Engineering and Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Emily A Bates
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Lee Niswander
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA.
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Breuss M, Morandell J, Nimpf S, Gstrein T, Lauwers M, Hochstoeger T, Braun A, Chan K, Sánchez Guajardo ER, Zhang L, Suplata M, Heinze KG, Elsayad K, Keays DA. The Expression of Tubb2b Undergoes a Developmental Transition in Murine Cortical Neurons. J Comp Neurol 2015; 523:2161-86. [PMID: 26105993 DOI: 10.1002/cne.23836] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 06/17/2015] [Accepted: 06/18/2015] [Indexed: 01/20/2023]
Abstract
The development of the mammalian brain requires the generation, migration, and differentiation of neurons, cellular processes that are dependent on a dynamic microtubule cytoskeleton. Mutations in tubulin genes, which encode for the structural subunits of microtubules, cause detrimental neurological disorders known as the tubulinopathies. The disease spectra associated with different tubulin genes are overlapping but distinct, an observation believed to reflect functional specification of this multigene family. Perturbation of the β-tubulin TUBB2B is known to cause polymicrogyria, pachygyria, microcephaly, and axon guidance defects. Here we provide a detailed analysis of the expression pattern of its murine homolog Tubb2b. The generation and characterization of BAC-transgenic eGFP reporter mouse lines has revealed that it is highly expressed in progenitors and postmitotic neurons during cortical development. This contrasts with the 8-week-old cortex, in which Tubb2b expression is restricted to macroglia, and expression is almost completely absent in mature neurons. This developmental transition in neurons is mirrored in the adult hippocampus and the cerebellum but is not a universal feature of Tubb2b; its expression persists in a population of postmitotic neurons in the 8-week-old retina. We propose that the dynamic spatial and temporal expression of Tubb2b reflects specific functional requirements of the microtubule cytoskeleton.
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Affiliation(s)
- Martin Breuss
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Jasmin Morandell
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Simon Nimpf
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Thomas Gstrein
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Mattias Lauwers
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Tobias Hochstoeger
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
| | - Andreas Braun
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria.,Centre for Genomic Regulation (CRG), 08003, Barcelona, Spain
| | - Kelvin Chan
- Medical Scientist Training Program, Stony Brook University Medical Center, Stony Brook, New York, 11794
| | | | - Lijuan Zhang
- Advanced Microscopy, Campus Science Support Facilities (CSF), Vienna, 1030, Austria
| | - Marek Suplata
- Rudolf Virchow Center, DFG-Research Center for Experimental Biomedicine of the University of Würzburg, Würzburg, 97080, Germany
| | - Katrin G Heinze
- Rudolf Virchow Center, DFG-Research Center for Experimental Biomedicine of the University of Würzburg, Würzburg, 97080, Germany
| | - Kareem Elsayad
- Advanced Microscopy, Campus Science Support Facilities (CSF), Vienna, 1030, Austria
| | - David A Keays
- IMP-Research Institute of Molecular Pathology, Vienna Biocenter (VBC), Vienna, 1030, Austria
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Nithianantham S, Le S, Seto E, Jia W, Leary J, Corbett KD, Moore JK, Al-Bassam J. Tubulin cofactors and Arl2 are cage-like chaperones that regulate the soluble αβ-tubulin pool for microtubule dynamics. eLife 2015. [PMID: 26208336 PMCID: PMC4574351 DOI: 10.7554/elife.08811] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Microtubule dynamics and polarity stem from the polymerization of
αβ-tubulin heterodimers. Five conserved tubulin cofactors/chaperones
and the Arl2 GTPase regulate α- and β-tubulin assembly into
heterodimers and maintain the soluble tubulin pool in the cytoplasm, but their
physical mechanisms are unknown. Here, we reconstitute a core tubulin chaperone
consisting of tubulin cofactors TBCD, TBCE, and Arl2, and reveal a cage-like
structure for regulating αβ-tubulin. Biochemical assays and electron
microscopy structures of multiple intermediates show the sequential binding of
αβ-tubulin dimer followed by tubulin cofactor TBCC onto this chaperone,
forming a ternary complex in which Arl2 GTP hydrolysis is activated to alter
αβ-tubulin conformation. A GTP-state locked Arl2 mutant inhibits
ternary complex dissociation in vitro and causes severe defects in microtubule
dynamics in vivo. Our studies suggest a revised paradigm for tubulin cofactors and
Arl2 functions as a catalytic chaperone that regulates soluble
αβ-tubulin assembly and maintenance to support microtubule
dynamics. DOI:http://dx.doi.org/10.7554/eLife.08811.001 Cells contain a network of protein filaments called microtubules. These filaments are
involved in many biological processes; for example, they help cells keep the right
shape, and they help to transport proteins and other materials inside cells. Two proteins called α-tubulin and β-tubulin are the building blocks of
microtubules. The filaments are very dynamic structures that can rapidly change
length as individual tubulin units are either added or removed to the filament ends.
Several proteins known as tubulin cofactors and an enzyme called Arl2 help to build a
vast pool of tubulin units that are able attach to the microtubules. These
units—called αβ-tubulin—are formed by α-tubulin
and β-tubulin binding to each other, but it not clear exactly what roles the
tubulin cofactors and Arl2 play in this process. Nithianantham et al. used a combination of microscopy and biochemical techniques to
study how the tubulin cofactors and Arl2 are organised, and their role in the
assembly of microtubules in yeast. The experiments show that Arl2 and two tubulin
cofactors associate with each other to form a stable ‘complex’ that has
a cage-like structure. A molecule of αβ-tubulin binds to the complex,
followed by another cofactor called TBCC. This activates the enzyme activity of Arl2,
which releases the energy needed to alter the shape of the αβ-tubulin.
Nithianantham et al. also found that yeast cells with a mutant form of Arl2 that
lacked enzyme activity had problems forming microtubules. Together, these findings show that the tubulin cofactors and Arl2 form a complex that
regulates the assembly and maintenance of αβ-tubulin. The next
challenge is to understand how this regulation influences the way that microtubules
grow and shrink inside cells. DOI:http://dx.doi.org/10.7554/eLife.08811.002
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Affiliation(s)
- Stanley Nithianantham
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| | - Sinh Le
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| | - Elbert Seto
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| | - Weitao Jia
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| | - Julie Leary
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
| | - Kevin D Corbett
- Ludwig Institute for Cancer Research, University of California, San Diego, San Diego, United States
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, United States
| | - Jawdat Al-Bassam
- Department of Molecular Cellular Biology, University of California, Davis, Davis, United States
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36
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Gonçalves J, Tavares A, Carvalhal S, Soares H. Revisiting the tubulin folding pathway: new roles in centrosomes and cilia. Biomol Concepts 2015; 1:423-34. [PMID: 25962015 DOI: 10.1515/bmc.2010.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Centrosomes and cilia are critical eukaryotic organelles which have been in the spotlight in recent years given their implication in a myriad of cellular and developmental processes. Despite their recognized importance and intense study, there are still many open questions about their biogenesis and function. In the present article, we review the existing data concerning members of the tubulin folding pathway and related proteins, which have been identified at centrosomes and cilia and were shown to have unexpected roles in these structures.
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37
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Veitia RA, Potier MC. Gene dosage imbalances: action, reaction, and models. Trends Biochem Sci 2015; 40:309-17. [PMID: 25937627 DOI: 10.1016/j.tibs.2015.03.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 03/17/2015] [Accepted: 03/27/2015] [Indexed: 12/29/2022]
Abstract
Single-gene deletions, duplications, and misregulation, as well as aneuploidy, can lead to stoichiometric imbalances within macromolecular complexes and cellular networks, causing their malfunction. Such alterations can be responsible for inherited or somatic genetic disorders including Mendelian diseases, aneuploid syndromes, and cancer. We review the effects of gene dosage alterations at the transcriptomic and proteomic levels, and the various responses of the cell to counteract their effects. Furthermore, we explore several biochemical models and ideas that can provide the rationale for treatments modulating the effects of gene dosage imbalances.
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Affiliation(s)
- Reiner A Veitia
- Institut Jacques Monod, Paris, France; Université Paris Diderot, Paris, France.
| | - Marie Claude Potier
- Sorbonne Universités, Université Pierre et Marie Curie (UPMC), Université Paris 06, Institut National de la Santé et de la Recherche Médicale (INSERM) and Centre National de la Recherche Scientifique (CNRS) Unités de Recherche U75, U1127, U7225, and Institut du Cerveau et de la Moelle Épinière (ICM), 75013 Paris, France
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38
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Serna M, Carranza G, Martín-Benito J, Janowski R, Canals A, Coll M, Zabala JC, Valpuesta JM. The structure of the complex between α-tubulin, TBCE and TBCB reveals a tubulin dimer dissociation mechanism. J Cell Sci 2015; 128:1824-34. [PMID: 25908846 DOI: 10.1242/jcs.167387] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 03/16/2015] [Indexed: 11/20/2022] Open
Abstract
Tubulin proteostasis is regulated by a group of molecular chaperones termed tubulin cofactors (TBC). Whereas tubulin heterodimer formation is well-characterized biochemically, its dissociation pathway is not clearly understood. Here, we carried out biochemical assays to dissect the role of the human TBCE and TBCB chaperones in α-tubulin-β-tubulin dissociation. We used electron microscopy and image processing to determine the three-dimensional structure of the human TBCE, TBCB and α-tubulin (αEB) complex, which is formed upon α-tubulin-β-tubulin heterodimer dissociation by the two chaperones. Docking the atomic structures of domains of these proteins, including the TBCE UBL domain, as we determined by X-ray crystallography, allowed description of the molecular architecture of the αEB complex. We found that heterodimer dissociation is an energy-independent process that takes place through a disruption of the α-tubulin-β-tubulin interface that is caused by a steric interaction between β-tubulin and the TBCE cytoskeleton-associated protein glycine-rich (CAP-Gly) and leucine-rich repeat (LRR) domains. The protruding arrangement of chaperone ubiquitin-like (UBL) domains in the αEB complex suggests that there is a direct interaction of this complex with the proteasome, thus mediating α-tubulin degradation.
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Affiliation(s)
- Marina Serna
- Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología (CNB-CSIC), Madrid 28049, Spain
| | - Gerardo Carranza
- Departamento de Biología Molecular, Facultad de Medicina, IDIVAL-Universidad de Cantabria, Santander 39011, Spain
| | - Jaime Martín-Benito
- Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología (CNB-CSIC), Madrid 28049, Spain
| | - Robert Janowski
- Departamento de Biología Estructural y Computacional, Institute for Research in Biomedicine (IRB-Barcelona), Barcelona 08028, Spain Departamento de Biología Estructural, Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona 08028, Spain
| | - Albert Canals
- Departamento de Biología Estructural y Computacional, Institute for Research in Biomedicine (IRB-Barcelona), Barcelona 08028, Spain Departamento de Biología Estructural, Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona 08028, Spain
| | - Miquel Coll
- Departamento de Biología Estructural y Computacional, Institute for Research in Biomedicine (IRB-Barcelona), Barcelona 08028, Spain Departamento de Biología Estructural, Institut de Biologia Molecular de Barcelona (IBMB-CSIC), Barcelona 08028, Spain
| | - Juan Carlos Zabala
- Departamento de Biología Molecular, Facultad de Medicina, IDIVAL-Universidad de Cantabria, Santander 39011, Spain
| | - José María Valpuesta
- Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología (CNB-CSIC), Madrid 28049, Spain
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39
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Zhang X, Chen X, Jiang J, Yu M, Yin Y, Ma Z. The tubulin cofactor A is involved in hyphal growth, conidiation and cold sensitivity in Fusarium asiaticum. BMC Microbiol 2015; 15:35. [PMID: 25886735 PMCID: PMC4342098 DOI: 10.1186/s12866-015-0374-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 02/04/2015] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Tubulin cofactor A (TBCA), one of the members of tubulin cofactors, is of great importance in microtubule functions through participating in the folding of α/β-tubulin heterodimers in Saccharomyces cerevisiae. However, little is known about the roles of TBCA in filamentous fungi. RESULTS In this study, we characterized a TBCA orthologue FaTBCA in Fusarium asiaticum. The deletion of FaTBCA caused dramatically reduced mycelial growth and abnormal conidiation. The FaTBCA deletion mutant (ΔFaTBCA-3) showed increased sensitivity to low temperatures and even lost the ability of growth at 4°C. Microscopic observation found that hyphae of ΔFaTBCA-3 exhibited blebbing phenotypes after shifting from 25 to 4°C for 1- or 3-day incubation and approximately 72% enlarged nodes contained several nuclei after 3-day incubation at 4°C. However, hyphae of the wild type incubated at 4°C were phenotypically indistinguishable from those incubated at 25°C. These results indicate that FaTBCA is involved in cell division under cold stress (4°C) in F. asiaticum. Unexpectedly, ΔFaTBCA-3 did not exhibit increased sensitivity to the anti-microtubule drug carbendazim although quantitative real-time assays showed that the expression of FaTBCA was up-regulated after treatment with carbendazim. In addition, pathogenicity assays showed that ΔFaTBCA-3 exhibited decreased virulence on wheat head and on non-host tomato. CONCLUSION Taken together, results of this study indicate that FaTBCA plays crucial roles in vegetative growth, conidiation, temperature sensitivity and virulence in F. asiaticum.
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Affiliation(s)
- Xiaoping Zhang
- Institute of Biotechnology, Zhejiang University, Hangzhou, China.
| | - Xiang Chen
- Institute of Biotechnology, Zhejiang University, Hangzhou, China.
| | - Jinhua Jiang
- Institute of Agriculture Quality and Standard for Agro-products, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
| | - Menghao Yu
- Institute of Biotechnology, Zhejiang University, Hangzhou, China.
| | - Yanni Yin
- Institute of Biotechnology, Zhejiang University, Hangzhou, China.
| | - Zhonghua Ma
- Institute of Biotechnology, Zhejiang University, Hangzhou, China.
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40
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Johnson CR, Weems AD, Brewer JM, Thorner J, McMurray MA. Cytosolic chaperones mediate quality control of higher-order septin assembly in budding yeast. Mol Biol Cell 2015; 26:1323-44. [PMID: 25673805 PMCID: PMC4454179 DOI: 10.1091/mbc.e14-11-1531] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Septin hetero-oligomers polymerize into cytoskeletal filaments with essential functions in many eukaryotic cell types. Mutations within the oligomerization interface that encompasses the GTP-binding pocket of a septin (its "G interface") cause thermoinstability of yeast septin hetero-oligomer assembly, and human disease. When coexpressed with its wild-type counterpart, a G interface mutant is excluded from septin filaments, even at moderate temperatures. We show that this quality control mechanism is specific to G interface mutants, operates during de novo septin hetero-oligomer assembly, and requires specific cytosolic chaperones. Chaperone overexpression lowers the temperature permissive for proliferation of cells expressing a G interface mutant as the sole source of a given septin. Mutations that perturb the septin G interface retard release from these chaperones, imposing a kinetic delay on the availability of nascent septin molecules for higher-order assembly. Un-expectedly, the disaggregase Hsp104 contributes to this delay in a manner that does not require its "unfoldase" activity, indicating a latent "holdase" activity toward mutant septins. These findings provide new roles for chaperone-mediated kinetic partitioning of non-native proteins and may help explain the etiology of septin-linked human diseases.
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Affiliation(s)
- Courtney R Johnson
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Andrew D Weems
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Jennifer M Brewer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Jeremy Thorner
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Michael A McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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41
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McMurray M. Lean forward: Genetic analysis of temperature-sensitive mutants unfolds the secrets of oligomeric protein complex assembly. Bioessays 2014; 36:836-46. [PMID: 25048147 DOI: 10.1002/bies.201400062] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Multisubunit protein complexes are essential for cellular function. Genetic analysis of essential processes requires special tools, among which temperature-sensitive (Ts) mutants have historically been crucial. Many researchers assume that the effect of temperature on such mutants is to drive their proteolytic destruction. In fact, degradation-mediated elimination of mutant proteins likely explains only a fraction of the phenotypes associated with Ts mutants. Here I discuss insights gained from analysis of Ts mutants in oligomeric proteins, with particular focus on the study of septins, GTP-binding subunits of cytoskeletal filaments whose structures and functions are the subject of current investigation in my and many other labs. I argue that the kinds of unbiased forward genetic approaches that generate Ts mutants provide information that is largely inaccessible to modern reverse genetic methodologies, and will continue to drive our understanding of higher-order assembly by septins and other oligomeric proteins.
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Affiliation(s)
- Michael McMurray
- Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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42
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Bellouze S, Schäfer MK, Buttigieg D, Baillat G, Rabouille C, Haase G. Golgi fragmentation in pmn mice is due to a defective ARF1/TBCE cross-talk that coordinates COPI vesicle formation and tubulin polymerization. Hum Mol Genet 2014; 23:5961-75. [DOI: 10.1093/hmg/ddu320] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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43
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Ruiz M, Martínez-Vidal AF, Morales JM, Monleón D, Giménez Y Ribotta M. Neurodegenerative changes are prevented by Erythropoietin in the pmn model of motoneuron degeneration. Neuropharmacology 2014; 83:137-53. [PMID: 24769002 DOI: 10.1016/j.neuropharm.2014.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 03/02/2014] [Accepted: 04/10/2014] [Indexed: 11/29/2022]
Abstract
Motoneuron diseases are fatal neurodegenerative disorders characterized by a progressive loss of motoneurons, muscle weakness and premature death. The progressive motor neuronopathy (pmn) mutant mouse has been considered a good model for the autosomal recessive childhood form of spinal muscular atrophy (SMA). Here, we investigated the therapeutic potential of Erythropoietin (Epo) on this mutant mouse. Symptomatic or pre-symptomatic treatment with Epo significantly prolongs lifespan by 84.6% or 87.2% respectively. Epo preserves muscle strength and significantly attenuates behavioural motor deficits of mutant pmn mice. Histological and metabolic changes in the spinal cord evaluated by immunohistochemistry, western blot, and high-resolution (1)H-NMR spectroscopy were also greatly prevented by Epo-treatment. Our results illustrate the efficacy of Epo in improving quality of life of mutant pmn mice and open novel therapeutic pathways for motoneuron diseases.
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Affiliation(s)
- Marta Ruiz
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad Miguel Hernández (UMH), Av. Ramón y Cajal s/n, 03550 San Juan de Alicante, Alicante, Spain
| | - Ana Fe Martínez-Vidal
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad Miguel Hernández (UMH), Av. Ramón y Cajal s/n, 03550 San Juan de Alicante, Alicante, Spain
| | - José Manuel Morales
- Unidad Central de Investigación en Medicina, Universidad de Valencia, Valencia, Spain
| | - Daniel Monleón
- Fundación de Investigación del Hospital Clínico Universitario de Valencia (FIHCUV), Valencia, Spain
| | - Minerva Giménez Y Ribotta
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC) - Universidad Miguel Hernández (UMH), Av. Ramón y Cajal s/n, 03550 San Juan de Alicante, Alicante, Spain.
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44
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Tian G, Cowan NJ. Tubulin-specific chaperones: components of a molecular machine that assembles the α/β heterodimer. Methods Cell Biol 2014; 115:155-71. [PMID: 23973072 DOI: 10.1016/b978-0-12-407757-7.00011-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The tubulin heterodimer consists of one α- and one β-tubulin polypeptide. Neither protein can partition to the native state or assemble into polymerization competent heterodimers without the concerted action of a series of chaperone proteins including five tubulin-specific chaperones (TBCs) termed TBCA-TBCE. TBCA and TBCB bind to and stabilize newly synthesized quasi-native β- and α-tubulin polypeptides, respectively, following their generation via multiple rounds of ATP-dependent interaction with the cytosolic chaperonin. There is free exchange of β-tubulin between TBCA and TBCD, and of α-tubulin between TBCB and TBCE, resulting in the formation of TBCD/β and TBCE/α, respectively. The latter two complexes interact, forming a supercomplex (TBCE/α/TBCD/β). Discharge of the native α/β heterodimer occurs via interaction of the supercomplex with TBCC, which results in the triggering of TBC-bound β-tubulin (E-site) GTP hydrolysis. This reaction acts as a switch for disassembly of the supercomplex and the release of E-site GDP-bound heterodimer, which becomes polymerization competent following spontaneous exchange with GTP. The tubulin-specific chaperones thus function together as a tubulin assembly machine, marrying the α- and β-tubulin subunits into a tightly associated heterodimer. The existence of this evolutionarily conserved pathway explains why it has never proved possible to isolate α- or β-tubulin as stable independent entities in the absence of their cognate partners, and implies that each exists and is maintained in the heterodimer in a nonminimal energy state. Here, we describe methods for the purification of recombinant TBCs as biologically active proteins following their expression in a variety of host/vector systems.
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Affiliation(s)
- Guoling Tian
- Department of Biochemistry and Molecular Pharmacology, New York University Langone Medical Center, New York, New York, USA
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45
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Mori R, Toda T. The dual role of fission yeast Tbc1/cofactor C orchestrates microtubule homeostasis in tubulin folding and acts as a GAP for GTPase Alp41/Arl2. Mol Biol Cell 2013; 24:1713-24, S1-8. [PMID: 23576550 PMCID: PMC3667724 DOI: 10.1091/mbc.e12-11-0792] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 02/22/2013] [Accepted: 03/29/2013] [Indexed: 11/11/2022] Open
Abstract
Supplying the appropriate amount of correctly folded α/β-tubulin heterodimers is critical for microtubule dynamics. Formation of assembly-competent heterodimers is remarkably elaborate at the molecular level, in which the α- and β-tubulins are separately processed in a chaperone-dependent manner. This sequential step is performed by the tubulin-folding cofactor pathway, comprising a specific set of regulatory proteins: cofactors A-E. We identified the fission yeast cofactor: the orthologue of cofactor C, Tbc1. In addition to its roles in tubulin folding, Tbc1 acts as a GAP in regulating Alp41/Arl2, a highly conserved small GTPase. Of interest, the expression of GDP- or GTP-bound Alp41 showed the identical microtubule loss phenotype, suggesting that continuous cycling between these forms is important for its functions. In addition, we found that Alp41 interacts with Alp1(D), the orthologue of cofactor D, specifically when in the GDP-bound form. Intriguingly, Alp1(D) colocalizes with microtubules when in excess, eventually leading to depolymerization, which is sequestered by co-overproducing GDP-bound Alp41. We present a model of the final stages of the tubulin cofactor pathway that includes a dual role for both Tbc1 and Alp1(D) in opposing regulation of the microtubule.
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Affiliation(s)
- Risa Mori
- Cell Regulation Laboratory, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3LY, United Kingdom
| | - Takashi Toda
- Cell Regulation Laboratory, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3LY, United Kingdom
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46
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Ghosh S, Kaplan KJ, Schrum LW, Bonkovsky HL. Cytoskeletal proteins: shaping progression of hepatitis C virus-induced liver disease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 302:279-319. [PMID: 23351713 DOI: 10.1016/b978-0-12-407699-0.00005-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hepatitis C virus (HCV) infection, which results in chronic hepatitis C (CHC) in most patients (70-85%), is a major cause of liver disease and remains a major therapeutic challenge. The mechanisms determining liver damage and the key factors that lead to a high rate of CHC remain imperfectly understood. The precise role of cytoskeletal (CS) proteins in HCV infection remains to be determined. Some studies including our recent study have demonstrated that changes occur in the expression of CS proteins in HCV-infected hepatocytes. A variety of host proteins interact with HCV proteins. Association between CS and HCV proteins may have implications in future design of CS protein-targeted therapy for the treatment for HCV infection. This chapter will focus on the interaction between host CS and viral proteins to signify the importance of this event in HCV entry, replication and transportation.
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Affiliation(s)
- Sriparna Ghosh
- Liver-Biliary-Pancreatic Center, Carolinas Medical Center, and School of Medicine, University of North Carolina, Carolinas Medical Center, Charlotte, NC, USA.
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Ludueña RF. A Hypothesis on the Origin and Evolution of Tubulin. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 302:41-185. [DOI: 10.1016/b978-0-12-407699-0.00002-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Abstract
The alpha-beta tubulin heterodimer is the subunit from which microtubules are assembled. The pathway leading to correctly folded alpha- and beta-tubulins is unusually complex: it involves cycles of ATP-dependent interaction of newly synthesized tubulin subunits with cytosolic chaperonin, resulting in the production of quasi-native folding intermediates, which must then be acted upon by additional protein cofactors. These cofactors form a supercomplex containing both alpha- and beta-tubulin polypeptides, from which native heterodimer is released in a GTP-dependent reaction. Here, we discuss the current state of our understanding of the function of cytosolic chaperonin and cofactors in tubulin folding.
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Fabrizio JJ, Aqeel N, Cote J, Estevez J, Jongoy M, Mangal V, Tema W, Rivera A, Wnukowski J, Bencosme Y. Mulet (mlt) encodes a tubulin-binding cofactor E-like homolog required for spermatid individualization in Drosophila melanogaster. Fly (Austin) 2012; 6:261-72. [PMID: 22885996 DOI: 10.4161/fly.21533] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Spermatogenesis in all animal species occurs within a syncytium. Only at the very end of spermatogenesis are individual sperm cells resolved from this syncytium in a process known as individualization. Individualization in Drosophila begins as a membrane-cytoskeletal complex known as the individualization complex (IC) assembles around the sperm heads and proceeds down the flagella, removing cytoplasm from between the sperm tails and shrink-wrapping each spermatid into its own plasma membrane as it travels. The mulet (mlt) mutation results in severely disrupted ICs, indicating that the mlt gene product is required for individualization. Inverse PCR followed by cycle sequencing maps all known P-insertion alleles of mlt to two overlapping genes, CG12214 (the Drosophila tubulin-binding cofactor E-like homolog) and KCNQ (a large voltage-gated potassium channel). However, since the alleles of mlt map to the 5'-UTR of CG12214 and since CG12214 is contained within an intron of KCNQ, it was hypothesized that mlt and CG12214 are allelic. Indeed, CG12214 mutant testes exhibited severely disrupted ICs and were indistinguishable from mlt mutant testes, thus further suggesting allelism. To test this hypothesis, alleles of mlt were crossed to CG12214 in order to generate trans-heterozygous males. Testes from all trans-heterozygous combinations revealed severely disrupted ICs and were also indistinguishable from mlt mutant testes, indicating that mlt and CG12214 fail to complement one another and are thus allelic. In addition, complementation testing against null alleles of KCNQ verified that the observed individualization defect is not caused by a disruption of KCNQ. Finally, since a population of spermatid-associated microtubules known to disappear prior to movement of the IC abnormally persists during individualization in CG12214 mutant testes, this work implicates TBCE-like in the removal of these microtubules prior to IC movement. Taken together, these results identify mlt as CG12214 and suggest that the removal of microtubules by TBCE-like is a necessary pre-requisite for proper coordinated movement of the IC.
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Affiliation(s)
- James J Fabrizio
- Biology Department, Division of Natural Sciences, College of Mount Saint Vincent, Riverdale, NY, USA.
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Baffet AD, Benoit B, Januschke J, Audo J, Gourhand V, Roth S, Guichet A. Drosophila tubulin-binding cofactor B is required for microtubule network formation and for cell polarity. Mol Biol Cell 2012; 23:3591-601. [PMID: 22855530 PMCID: PMC3442407 DOI: 10.1091/mbc.e11-07-0633] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Microtubules (MTs) are essential for cell division, shape, intracellular transport, and polarity. MT stability is regulated by many factors, including MT-associated proteins and proteins controlling the amount of free tubulin heterodimers available for polymerization. Tubulin-binding cofactors are potential key regulators of free tubulin concentration, since they are required for α-β-tubulin dimerization in vitro. In this paper, we show that mutation of the Drosophila tubulin-binding cofactor B (dTBCB) affects the levels of both α- and β-tubulins and dramatically destabilizes the MT network in different fly tissues. However, we find that dTBCB is dispensable for the early MT-dependent steps of oogenesis, including cell division, and that dTBCB is not required for mitosis in several tissues. In striking contrast, the absence of dTBCB during later stages of oogenesis causes major defects in cell polarity. We show that dTBCB is required for the polarized localization of the axis-determining mRNAs within the oocyte and for the apico-basal polarity of the surrounding follicle cells. These results establish a developmental function for the dTBCB gene that is essential for viability and MT-dependent cell polarity, but not cell division.
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Affiliation(s)
- Alexandre D Baffet
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
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