UMR3348 – Intégrité du génome, ARN et cancer

Publications de l’unité

Année de publication : 2017

Carsten Janke, Guillaume Montagnac (2017 Dec 4)

Causes and Consequences of Microtubule Acetylation.

Current biology : CB : R1287-R1292 : DOI : S0960-9822(17)31381-7 En savoir plus
Résumé

Among the different types of cytoskeletal components, microtubules arguably accumulate the greatest diversity of post-translational modifications (PTMs). Acetylation of lysine 40 (K40) of α-tubulin has received particular attention because it is the only tubulin PTM to be found in the lumen of microtubules: most other tubulin PTMs are found at the outer surface of the microtubule. As a consequence, the enzyme catalyzing K40 acetylation needs to penetrate the narrow microtubule lumen to find its substrate. Acetylated microtubules have been considered to be stable, long-lived microtubules; however, until recently, there was little information about whether the longevity of these microtubules is the cause or the consequence of acetylation. Current advances suggest that this PTM helps the microtubule lattice to cope with mechanical stress, thus facilitating microtubule self-repair. These observations now shed new light on the structural integrity of microtubules, as well as on the mechanisms and biological functions of tubulin acetylation. Here, we discuss recent insights into how acetylation is generated in the lumen of microtubules, and how this ‘hidden’ PTM can control the properties and functions of microtubules.

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Alexis Fouquin, Josée Guirouilh-Barbat, Bernard Lopez, Janet Hall, Mounira Amor-Guéret, Vincent Pennaneach (2017 Dec 1)

PARP2 controls double-strand break repair pathway choice by limiting 53BP1 accumulation at DNA damage sites and promoting end-resection.

Nucleic acids research : DOI : 10.1093/nar/gkx881 En savoir plus
Résumé

Double strand breaks (DSBs) are one of the most toxic lesions to cells. DSB repair by the canonical non-homologous end-joining (C-EJ) pathway involves minor, if any, processing of the broken DNA-ends, whereas the initiation of DNA resection channels the broken-ends toward DNA repair pathways using various lengths of homology. Mechanisms that control the resection initiation are thus central to the regulation to the choice of DSB repair pathway. Therefore, understanding the mechanisms which regulate the initiation of DNA end-resection is of prime importance. Our findings reveal that poly(ADP-ribose) polymerase 2 (PARP2) is involved in DSBR pathway choice independently of its PAR synthesis activity. We show that PARP2 favors repair by homologous recombination (HR), single strand annealing (SSA) and alternative-end joining (A-EJ) rather than the C-EJ pathway and increases the deletion sizes at A-EJ junctions. We demonstrate that PARP2 specifically limits the accumulation of the resection barrier factor 53BP1 at DNA damage sites, allowing efficient CtIP-dependent DNA end-resection. Collectively, we have identified a new PARP2 function, independent of its PAR synthesis activity, which directs DSBs toward resection-dependent repair pathways.

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Takashi Akera, Lukáš Chmátal, Emily Trimm, Karren Yang, Chanat Aonbangkhen, David M Chenoweth, Carsten Janke, Richard M Schultz, Michael A Lampson (2017 Nov 3)

Spindle asymmetry drives non-Mendelian chromosome segregation.

Science (New York, N.Y.) : 668-672 : DOI : 10.1126/science.aan0092 En savoir plus
Résumé

Genetic elements compete for transmission through meiosis, when haploid gametes are created from a diploid parent. Selfish elements can enhance their transmission through a process known as meiotic drive. In female meiosis, selfish elements drive by preferentially attaching to the egg side of the spindle. This implies some asymmetry between the two sides of the spindle, but the molecular mechanisms underlying spindle asymmetry are unknown. Here we found that CDC42 signaling from the cell cortex regulated microtubule tyrosination to induce spindle asymmetry and that non-Mendelian segregation depended on this asymmetry. Cortical CDC42 depends on polarization directed by chromosomes, which are positioned near the cortex to allow the asymmetric cell division. Thus, selfish meiotic drivers exploit the asymmetry inherent in female meiosis to bias their transmission.

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Michelle Newman, Rym Sfaxi, Abhijit Saha, David Monchaud, Marie-Paule Teulade-Fichou, Stéphan Vagner (2017 Oct 27)

The G-Quadruplex-Specific RNA Helicase DHX36 Regulates p53 Pre-mRNA 3′-End Processing Following UV-Induced DNA Damage.

Journal of Molecular Biology : 429 : 3121-3131 : DOI : 10.1016/j.jmb.2016.11.033 En savoir plus
Résumé

Pre-mRNA 3′-end processing, the process through which almost all eukaryotic mRNAs acquire a poly(A) tail is generally inhibited during the cellular DNA damage response leading to a profound impact on the level of protein expression since unprocessed transcripts at the 3′-end will be degraded or unable to be transported to the cytoplasm. However, a compensatory mechanism involving the binding of the hnRNP H/F family of RNA binding proteins to an RNA G-quadruplex (G4) structure located in the vicinity of a polyadenylation site has previously been described to allow the transcript encoding the p53 tumour suppressor protein to be properly processed during DNA damage and to provide the cells with a way to react to DNA damage. Here we report that the DEAH (Asp-Glu-Ala-His) box RNA helicase DHX36/RHAU/G4R1, which specifically binds to and resolves parallel-stranded G4, is necessary to maintain p53 pre-mRNA 3′-end processing following UV-induced DNA damage. DHX36 binds to the p53 RNA G4, while mutation of the G4 impairs the ability of DHX36 to maintain pre-mRNA 3′-end processing. Stabilization of the p53 RNA G4 with two different G4 ligands ((PNA)DOTASQ and PhenDC3), which is expected from previous studies to prevent DHX36 from binding and unwinding G4s, also impairs p53 pre-mRNA 3′-end processing following UV. Our work identifies DHX36 as a new actor in the compensatory mechanisms that are in place to ensure that the mRNAs encoding p53 are still processed following UV.

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Martin Dutertre, Stéphan Vagner (2017 Oct 27)

DNA-Damage response RNA-Binding Proteins (DDRBPs): Perspectives from a new class of proteins and their RNA targets.

Journal of molecular biology : DOI : 10.1016/j.jmb.2016.09.019 En savoir plus
Résumé

Upon DNA damage, cells trigger an early DNA-damage response (DDR) involving DNA repair and cell cycle checkpoints, and late responses involving gene expression regulation that determine cell fate. Screens for genes involved in the DDR have found many RNA-binding proteins (RBPs), while screens for novel RBPs have identified DDR proteins. An increasing number of RBPs are involved in the early and/or late DDR. We propose to call this new class of actors of the DDR that contain an RNA-binding activity, DNA-damage response RNA-binding proteins (DDRBPs). We then discuss how DDRBPs not only contribute to gene expression regulation in the late DDR, but also to early DDR signaling, DNA repair and chromatin modifications at DNA damage sites through interactions with both long and short noncoding RNAs.

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Elias Bou Samra, Géraldine Buhagiar-Labarchède, Christelle Machon, Jérôme Guitton, Rosine Onclercq-Delic, Michael R Green, Olivier Alibert, Claude Gazin, Xavier Veaute, Mounira Amor-Guéret (2017 Sep 25)

A role for Tau protein in maintaining ribosomal DNA stability and cytidine deaminase-deficient cell survival.

Nature communications : 693 : DOI : 10.1038/s41467-017-00633-1 En savoir plus
Résumé

Cells from Bloom’s syndrome patients display genome instability due to a defective BLM and the downregulation of cytidine deaminase. Here, we use a genome-wide RNAi-synthetic lethal screen and transcriptomic profiling to identify genes enabling BLM-deficient and/or cytidine deaminase-deficient cells to tolerate constitutive DNA damage and replication stress. We found a synthetic lethal interaction between cytidine deaminase and microtubule-associated protein Tau deficiencies. Tau is overexpressed in cytidine deaminase-deficient cells, and its depletion worsens genome instability, compromising cell survival. Tau is recruited, along with upstream-binding factor, to ribosomal DNA loci. Tau downregulation decreases upstream binding factor recruitment, ribosomal RNA synthesis, ribonucleotide levels, and affects ribosomal DNA stability, leading to the formation of a new subclass of human ribosomal ultrafine anaphase bridges. We describe here Tau functions in maintaining survival of cytidine deaminase-deficient cells, and ribosomal DNA transcription and stability. Moreover, our findings for cancer tissues presenting concomitant cytidine deaminase underexpression and Tau upregulation open up new possibilities for anti-cancer treatment.Cytidine deaminase (CDA) deficiency leads to genome instability. Here the authors find a synthetic lethal interaction between CDA and the microtubule-associated protein Tau deficiencies, and report that Tau depletion affects rRNA synthesis, ribonucleotide pool balance, and rDNA stability.

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Sudarshan Gadadhar, Hala Dadi, Satish Bodakuntla, Anne Schnitzler, Ivan Bièche, Filippo Rusconi, Carsten Janke (2017 Sep 4)

Tubulin glycylation controls primary cilia length.

The Journal of cell biology : 2701-2713 : DOI : 10.1083/jcb.201612050 En savoir plus
Résumé

As essential components of the eukaryotic cytoskeleton, microtubules fulfill a variety of functions that can be temporally and spatially controlled by tubulin posttranslational modifications. Tubulin glycylation has so far been mostly found on motile cilia and flagella, where it is involved in the stabilization of the axoneme. In contrast, barely anything is known about the role of glycylation in primary cilia because of limitations in detecting this modification in these organelles. We thus developed novel glycylation-specific antibodies with which we detected glycylation in many primary cilia. Glycylation accumulates in primary cilia in a length-dependent manner, and depletion or overexpression of glycylating enzymes modulates the length of primary cilia in cultured cells. This strongly suggests that glycylation is essential for the homeostasis of primary cilia, which has important implications for human disorders related to primary cilia dysfunctions, such as ciliopathies and certain types of cancer.

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Richard Belvindrah, Kathiresan Natarajan, Preety Shabajee, Elodie Bruel-Jungerman, Jennifer Bernard, Marie Goutierre, Imane Moutkine, Xavier H Jaglin, Mythili Savariradjane, Theano Irinopoulou, Jean-Christophe Poncer, Carsten Janke, Fiona Francis (2017 Aug 7)

Mutation of the α-tubulin Tuba1a leads to straighter microtubules and perturbs neuronal migration.

The Journal of cell biology : 2443-2461 : DOI : 10.1083/jcb.201607074 En savoir plus
Résumé

Brain development involves extensive migration of neurons. Microtubules (MTs) are key cellular effectors of neuronal displacement that are assembled from α/β-tubulin heterodimers. Mutation of the α-tubulin isotype TUBA1A is associated with cortical malformations in humans. In this study, we provide detailed in vivo and in vitro analyses of Tuba1a mutants. In mice carrying a Tuba1a missense mutation (S140G), neurons accumulate, and glial cells are dispersed along the rostral migratory stream in postnatal and adult brains. Live imaging of Tuba1a-mutant neurons revealed slowed migration and increased neuronal branching, which correlated with directionality alterations and perturbed nucleus-centrosome (N-C) coupling. Tuba1a mutation led to increased straightness of newly polymerized MTs, and structural modeling data suggest a conformational change in the α/β-tubulin heterodimer. We show that Tuba8, another α-tubulin isotype previously associated with cortical malformations, has altered function compared with Tuba1a. Our work shows that Tuba1a plays an essential, noncompensated role in neuronal saltatory migration in vivo and highlights the importance of MT flexibility in N-C coupling and neuronal-branching regulation during neuronal migration.

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Zeina Bash-Imam, Gabriel Thérizols, Anne Vincent, Florian Lafôrets, Micaela Polay Espinoza, Nathalie Pion, Françoise Macari, Julie Pannequin, Alexandre David, Jean-Christophe Saurin, Hichem C Mertani, Julien Textoris, Didier Auboeuf, Frédéric Catez, Nicole Dalla Venezia, Martin Dutertre, Virginie Marcel, Jean-Jacques Diaz (2017 Jul 11)

Translational reprogramming of colorectal cancer cells induced by 5-fluorouracil through a miRNA-dependent mechanism.

Oncotarget : 46219-46233 : DOI : 10.18632/oncotarget.17597 En savoir plus
Résumé

5-Fluorouracil (5-FU) is a widely used chemotherapeutic drug in colorectal cancer. Previous studies showed that 5-FU modulates RNA metabolism and mRNA expression. In addition, it has been reported that 5-FU incorporates into the RNAs constituting the translational machinery and that 5-FU affects the amount of some mRNAs associated with ribosomes. However, the impact of 5-FU on translational regulation remains unclear. Using translatome profiling, we report that a clinically relevant dose of 5-FU induces a translational reprogramming in colorectal cancer cell lines. Comparison of mRNA distribution between polysomal and non-polysomal fractions in response to 5-FU treatment using microarray quantification identified 313 genes whose translation was selectively regulated. These regulations were mostly stimulatory (91%). Among these genes, we showed that 5-FU increases the mRNA translation of HIVEP2, which encodes a transcription factor whose translation in normal condition is known to be inhibited by mir-155. In response to 5-FU, the expression of mir-155 decreases thus stimulating the translation of HIVEP2 mRNA. Interestingly, the 5-FU-induced increase in specific mRNA translation was associated with reduction of global protein synthesis. Altogether, these findings indicate that 5-FU promotes a translational reprogramming leading to the increased translation of a subset of mRNAs that involves at least for some of them, miRNA-dependent mechanisms. This study supports a still poorly evaluated role of translational control in drug response.

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Simon Gemble, Géraldine Buhagiar-Labarchède, Rosine Onclercq-Delic, Christian Jaulin, Mounira Amor-Guéret (2017 Jun 3)

Cytidine deaminase deficiency impairs sister chromatid disjunction by decreasing PARP-1 activity.

Cell cycle (Georgetown, Tex.) : 1-8 : DOI : 10.1080/15384101.2017.1317413 En savoir plus
Résumé

Bloom Syndrome (BS) is a rare genetic disease characterized by high levels of chromosomal instability and an increase in cancer risk. Cytidine deaminase (CDA) expression is downregulated in BS cells, leading to an excess of cellular dC and dCTP that reduces basal PARP-1 activity, compromising optimal Chk1 activation and reducing the efficiency of downstream checkpoints. This process leads to the accumulation of unreplicated DNA during mitosis and, ultimately, ultrafine anaphase bridge (UFB) formation. BS cells also display incomplete sister chromatid disjunction when depleted of cohesin. Using a combination of fluorescence in situ hybridization and chromosome spreads, we investigated the possible role of CDA deficiency in the incomplete sister chromatid disjunction in cohesin-depleted BS cells. The decrease in basal PARP-1 activity in CDA-deficient cells compromised sister chromatid disjunction in cohesin-depleted cells, regardless of BLM expression status. The observed incomplete sister chromatid disjunction may be due to the accumulation of unreplicated DNA during mitosis in CDA-deficient cells, as reflected in the changes in centromeric DNA structure associated with the decrease in basal PARP-1 activity. Our findings reveal a new function of PARP-1 in sister chromatid disjunction during mitosis.

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Kathiresan Natarajan, Sudarshan Gadadhar, Judith Souphron, Maria M Magiera, Carsten Janke (2017 Jun 1)

Molecular interactions between tubulin tails and glutamylases reveal determinants of glutamylation patterns.

EMBO reports : 1013-1026 : DOI : 10.15252/embr.201643751 En savoir plus
Résumé

Posttranslational modifications of tubulin currently emerge as key regulators of microtubule functions. Polyglutamylation generates a variety of modification patterns that are essential for controlling microtubule functions in different cell types and organelles, and deregulation of these patterns has been linked to ciliopathies, cancer and neurodegeneration. How the different glutamylating enzymes determine precise modification patterns has so far remained elusive. Using computational modelling, molecular dynamics simulations and mutational analyses we now show how the carboxy-terminal tails of tubulin bind into the active sites of glutamylases. Our models suggest that the glutamylation sites on α- and β-tubulins are determined by the positioning of the tails within the catalytic pocket. Moreover, we found that the binding modes of α- and β-tubulin tails are highly similar, implying that most enzymes could potentially modify both, α- and β-tubulin. This supports a model in which the binding of the enzymes to the entire microtubule lattice, but not the specificity of the C-terminal tubulin tails to their active sites, determines the catalytic specificities of glutamylases.

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Hermela Shimelis, Romy L S Mesman, Catharina Von Nicolai, Asa Ehlen, Lucia Guidugli, Charlotte Martin, Fabienne Mgr Calleja, Huong Meeks, Emily Hallberg, Jamie Hinton, Jenna Lilyquist, Chunling Hu, Cora M Aalfs, Kristiina Aittomaki, Irene L Andrulis, Hoda Anton-Culver, Volker Arndt, Matthias W Beckmann, Javier J Benitez, Natalia Bogdanova, Stig E Bojesen, Manjeet K Bolla, Anne-Lise Borresen-Dale, Hiltrud Brauch, Paul Brennan, Hermann Brenner, Annegien Broeks, Barbara Brouwers, Thomas Bruning, Barbara Burwinkel, Jenny Chang-Claude, Georgia Chenevix-Trench, Ching-Yu Cheng, Ji-Yeob Choi, J Margriet Collée, Angela Cox, Simon S Cross, Kamila Czene, Hatef Darabi, Joe Dennis, Thilo Dork, Isabel Dos Santos Silva, Alison M Dunning, Peter A Fasching, Jonine D Figueroa, Henrik Flyger, Montserrat Garcia-Closas, Graham G Giles, Gord Glendon, Pascal Guenel, Christopher A Haiman, Per Hall, Ute Hamann, Mikael Hartman, Frans B L Hogervorst, Antoinette Hollestelle, John L Hopper, Hidemi Ito, Anna Jakubowska, Daehee Kang, Veli-Matti Kosma, Vessela Kristensen, Kah-Nyin Lai, Diether Lambrechts, Loic Le Marchand, Jingmei Li, Annika Lindblom, Artitaya Lophatananon, Jan Lubinski, Eva Machackova, Arto Mannermaa, Sara Margolin, Frederik Marme, Keitaro Matsuo, Hui Miao, Kyriaki Michailidou, Roger L Milne, Kenneth Muir, Susan L Neuhausen, Heli Nevanlinna, Janet E Olson, Curtis Olswold, Jan C Oosterwijk, Ana Osorio, Paolo Peterlongo, Julian Peto, Paul D P Pharoah, Katri Pylkäs, Paolo Radice, Muhammad U Rashid, Valerie Rhenius, Anja Rudolph, Suleeporn Sangrajrang, Elinor J Sawyer, Marjanka K Schmidt, Minouk J Schoemaker, Caroline M Seynaeve, Mitul Shah, Chen-Yang Shen, Martha J Shrubsole, Xiao-Ou Shu, Susan L Slager, Melissa C Southey, Daniel O Stram, Anthony J Swerdlow, Soo Hwang Teo, Ian Tomlinson, Diana Torres, Therese Truong, Christi J van Asperen, Lizet E van der Kolk, Qin Wang, Robert Winqvist, Anna H Wu, Jyh-Cherng Yu, Wei Zheng, Ying Zheng, Jennifer Leary, Logan C Walker, Lenka Foretova, Florentia Fostira, Kathleen Claes, Liliana Varesco, Setareh Moghadasi, Douglas F Easton, Amanda B Spurdle, Peter Devilee, Harry Vrieling, Alvaro N Monteiro, David E Goldgar, Aura Carreira, Maaike P G Vreeswijk, Fergus J Couch (2017 Jun 1)

BRCA2 hypomorphic missense variants confer moderate risks of breast cancer.

Cancer research : DOI : 10.1158/0008-5472.CAN-16-2568 En savoir plus
Résumé

Breast cancer risks conferred by many germline missense variants in the BRCA1 and BRCA2 genes, often referred to as variants of uncertain significance (VUS), have not been established. In this study, associations between 19 BRCA1 and 33 BRCA2 missense substitution variants and breast cancer risk were investigated through a breast cancer case control study using genotyping data from 38 studies of predominantly European ancestry (41,890 cases and 41,607 controls) and nine studies of Asian ancestry (6,269 cases and 6,624 controls). The BRCA2 c.9104A>C, p.Tyr3035Ser (OR=2.52, p=0.04) and BRCA1 c.5096G>A, p.Arg1699Gln (OR=4.29, p=0.009) variant were associated with moderately increased risks of breast cancer among Europeans, whereas BRCA2 c.7522G>A, p.Gly2508Ser (OR=2.68, p=0.004) and c.8187G>T, p.Lys2729Asn (OR=1.4, p=0.004) were associated with moderate and low risks of breast cancer among Asians. Functional characterization of the BRCA2 variants using four quantitative assays showed reduced BRCA2 activity for p.Tyr3035Ser compared to wildtype. Overall, our results show how BRCA2 missense variants that influence protein function can confer clinically relevant, moderately increased risks of breast cancer, with potential implications for risk management guidelines in women with these specific variants.

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Anissia Ait Saada, Ana Teixeira-Silva, Ismail Iraqui, Audrey Costes, Julien Hardy, Giulia Paoletti, Karine Fréon, Sarah A E Lambert (2017 May 4)

Unprotected Replication Forks Are Converted into Mitotic Sister Chromatid Bridges.

Molecular cell : 398-410.e4 : DOI : 10.1016/j.molcel.2017.04.002 En savoir plus
Résumé

Replication stress and mitotic abnormalities are key features of cancer cells. Temporarily paused forks are stabilized by the intra-S phase checkpoint and protected by the association of Rad51, which prevents Mre11-dependent resection. However, if a fork becomes dysfunctional and cannot resume, this terminally arrested fork is rescued by a converging fork to avoid unreplicated parental DNA during mitosis. Alternatively, dysfunctional forks are restarted by homologous recombination. Using fission yeast, we report that Rad52 and the DNA binding activity of Rad51, but not its strand-exchange activity, act to protect terminally arrested forks from unrestrained Exo1-nucleolytic activity. In the absence of recombination proteins, large ssDNA gaps, up to 3 kb long, occur behind terminally arrested forks, preventing efficient fork merging and leading to mitotic sister chromatid bridging. Thus, Rad52 and Rad51 prevent temporarily and terminally arrested forks from degrading and, despite the availability of converging forks, converting to anaphase bridges causing aneuploidy and cell death.

Free acces : authors.elsevier.com/a/1U~li3vVUP2C0m

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Hamza Mameri, Ivan Bieche, Dider Meseure, Elisabetta Marangoni, Géraldine Buhagiar-Labarchède, Andre Nicolas, Sophie Vacher, Rosine Onclercq-Delic, Vinodh Rajapakse, Sudhir Varma, William C Reinhold, Yves Pommier, Mounira Amor-Guéret (2017 Apr 15)

Cytidine deaminase deficiency reveals new therapeutic opportunities against cancer.

Clinical cancer research : an official journal of the American Association for Cancer Research : DOI : 10.1158/1078-0432.CCR-16-0626 En savoir plus
Résumé

One of the main challenges in cancer therapy is the identification of molecular mechanisms mediating resistance or sensitivity to treatment. Cytidine deaminase (CDA) was reported to be downregulated in cells derived from patients with Bloom syndrome, a genetic disease associated with a strong predisposition to a wide range of cancers. The purpose of this study was to determine whether CDA deficiency could be associated with tumors from the general population and could constitute a predictive marker of susceptibility to anti-tumor drugs.

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Sudarshan Gadadhar, Satish Bodakuntla, Kathiresan Natarajan, Carsten Janke (2017 Apr 15)

The tubulin code at a glance.

Journal of cell science : 1347-1353 : DOI : 10.1242/jcs.199471 En savoir plus
Résumé

Microtubules are key cytoskeletal elements of all eukaryotic cells and are assembled of evolutionarily conserved α-tubulin-β-tubulin heterodimers. Despite their uniform structure, microtubules fulfill a large diversity of functions. A regulatory mechanism to control the specialization of the microtubule cytoskeleton is the ‘tubulin code’, which is generated by (i) expression of different α- and β-tubulin isotypes, and by (ii) post-translational modifications of tubulin. In this Cell Science at a Glance article and the accompanying poster, we provide a comprehensive overview of the molecular components of the tubulin code, and discuss the mechanisms by which these components contribute to the generation of functionally specialized microtubules.

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