Biology subjects

Bettencourt-Dias, M.

Publications and source records attributed to Bettencourt-Dias, M..

10 recordsLinked to original sources

bioRxiv2026

Centrosome maintains the integrity of and repairs mature olfactory cilia in adult Drosophila

Mechanisms of cilium assembly are well studied; however, how mature metazoan cilia maintain their structures and functions in vivo remains unknown. It is also unclear whether the centrosome-derived basal body (BB) directly contributes to ciliary homeostasis. We combined biochemistry, genetics, high-resolution subcellular imaging, and electrophysiology to investigate long-lived ciliated olfactory sensory neurons (OSNs) and their olfactory behaviour in adult Drosophila. Several centrosome assembly proteins are absent, but another subset persists through dynamic protein exchange at the BBs of mature olfactory cilia. At this ciliary base, pericentriolar material (PCM) components, e.g., {gamma}-Tubulin23C, centrosomin, and pericentrin-like protein form an interconnected network required for ciliary maintenance. Adult- and OSN-specific depletions of these proteins, particularly in combination, disrupt accumulation of the heterotrimeric kinesin-2 at the ciliary base and, subsequently, in the shaft, causing loss of ciliary tubulin, EB1, and odorant receptor co-receptor. These dysregulations cause profound loss of ciliary shaft and impair olfactory function/behaviour. The centrosomal kinases PLK1/POLO and Aurora A also work with this PCM network and are required for mature ciliary homeostasis. Remarkably, these defects in ciliary structure, function, and adult olfactory behaviour are reversible, suggesting that this centrosome-derived BB is a dynamic homeostatic epicentre that regulates trafficking and ciliary structural and compositional integrity in vivo. These findings uncover an active, centrosome-dependent, cell-autonomous mechanism for maintaining and repairing mature metazoan cilia in fully grown organs in adulthood and also provide a possible explanation for how deregulation of conserved ciliary base components could lead to progressive, late-onset cilia-related disorders.

cell biology↗

bioRxiv2023

High prevalence and dependence of centrosome clustering in mesenchymal tumors and leukemia

The presence of supernumerary centrosomes is a hallmark of cancer and is frequently observed in aggressive tumors. Cancer cells with centrosome amplification achieve pseudo-bipolar spindles through specific coping mechanisms in order to survive. However, their distribution and prevalence in cancer remain largely unknown. Here, using the NCI60 panel of cancer cell lines, we show that the presence of coping strategies correlates with centrosome amplification, with the clustering of extra-centrosomes within the two spindle poles being the most widespread mechanism. Moreover, we report an association between centrosome clustering ability and the epithelial-to-mesenchymal transition (EMT) and observe that the induction of mesenchymal characteristics in breast cancer cells with centrosome amplification promotes clustering. Furthermore, we unveil hematological malignancies, which lack epithelial characteristics, as the most proficient in centrosome clustering. Finally, we show that acute lymphoblastic leukemia is particularly sensitive to targeting clustering through inhibition of the spindle assembly checkpoint. Our study reveals how centrosome clustering and the EMT collaborate to promote carcinogenesis, suggesting new possibilities to treat tumors with low epithelial characteristics, in particular leukemias. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=74 SRC="FIGDIR/small/532472v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@12a713dorg.highwire.dtl.DTLVardef@1706edborg.highwire.dtl.DTLVardef@7deea7org.highwire.dtl.DTLVardef@1bf2280_HPS_FORMAT_FIGEXP M_FIG C_FIG O_LICentrosome clustering is widespread in the NCI60 panel and particularly strong in leukemia. C_LIO_LIThe EMT enhances the ability of cancer cells to cope with multiple centrosomes through centrosome clustering. C_LIO_LICentrosome clustering gene expression peaks at the invasive stage and has prognostic value in breast cancer. C_LIO_LIThe inhibition of MPS1 is a good strategy to promote the death of acute lymphoblastic leukemia (ALL) cells with CA. C_LI

cancer biology↗

bioRxiv2022

McIdas localizes at centrioles and controls centriole numbers through PLK4-dependent phosphorylation

The centriole duplication cycle must be tightly controlled and coordinated with the chromosome cycle. Aberrations in centriole biogenesis can lead to cancer, developmental disorders and ciliopathies. Here, we show that McIdas -previously implicated in cell cycle control and centriole amplification in multiciliated cells-is critical to maintain centriole numbers. Using expansion microscopy, we demonstrate that McIdas is present at the middle part of centrioles, where it exhibits a differential localization during the cell cycle. McIdas loss perturbs daughter centriole biogenesis and centrosomal SAS6 recruitment, whereas its overexpression induces centriole overduplication. Consistently, McIdas depletion reduces PLK4-induced centriole amplification. McIdas interacts with and is phosphorylated by PLK4 in multiple sites identified by mass spectrometry. Mutational analysis shows that McIdas phosphorylation is important for centriole number control. Overall, our results identify a novel, direct role of McIdas on centriole duplication that can link its previously characterized roles in the chromosome cycle and multiciliogenesis.

molecular biology↗

bioRxiv2022

Ana1/CEP295 is an essential player in the centrosome maintenance program regulated by Polo kinase

Centrioles play critical roles in our cells, being part of centrosomes and cilia, which are important microtubule organising centers (MTOC) with a variety of roles. While centrioles are very stable structures, they disappear in certain cell types upon differentiation, such as in oocytes. Little is known about the regulation of centriole structural integrity. We previously uncovered that the pericentriolar material (PCM), and its recruiter Polo kinase, are required for both the maintenance of centriole structural integrity and centrosome MTOC activity. Using an hypothesis driven RNAi screen, we show that both the cartwheel and the centriole wall play an important role in centrosome integrity. In particular, we uncovered that the centriole wall protein ANA1 is critical for the integrity of both new and mature centrioles, in Drosophila oogenesis as well as in cultured cells. Moreover, our results show that the activity of both Polo and the PCM in centriole integrity depends on ANA1. Our work suggests that the structural integrity of centrioles, once thought to be very stable organelles, depends on the turnover of key components, suggesting new perspectives for understanding the dysfunction of those structures in disease.

cell biology↗

bioRxiv2020

The 3D architecture and molecular foundations of de novo centriole assembly via bicentrioles

Abstract/SummaryCentrioles are structurally conserved organelles, composing both centrosomes and cilia. In animal cycling cells, centrioles often form through a highly characterized process termed canonical duplication. However, a large diversity of eukaryotes form centrioles de novo through uncharacterized pathways. This unexplored diversity is key to understanding centriole assembly mechanisms and how they evolved to assist specific cellular functions. Here, combining electron microscopy and tomography, we show that during spermatogenesis of the moss Physcomitrium patens, centrioles are born as a co-axially oriented centriole pair united by a cartwheel. We observe that microtubules emanate from those bicentrioles, which localize to the spindle poles during cell division. Thereafter, each bicentriole breaks apart, and the two resulting sister centrioles mature asymmetrically, elongating specific microtubule triplets and a naked cartwheel. Subsequently, two cilia are assembled which are capable of beating asynchronously. We further show that conserved cartwheel and centriole wall components, SAS6, BLD10 and POC1 are expressed during spermatogenesis and are required for this de novo biogenesis pathway. Our work supports a scenario where centriole biogenesis is more diverse than previously thought and that conserved molecular modules underlie diversification of this essential pathway.

cell biology↗

bioRxiv2020

IFT88 transports Gucy2d, a guanylyl cyclase, to maintain sensory cilia function in Drosophila

Cilia are involved in a plethora of motility and sensory-related functions. Ciliary defects cause several ciliopathies, some of which with late-onset, suggesting cilia are actively maintained. While much is known about cilia assembly, little is understood about the mechanisms of their maintenance. Given that intraflagellar transport (IFT) is essential for cilium assembly, we investigated the role of one of its main players, IFT88, in ciliary maintenance. We show that DmIFT88, the Drosophila melanogaster orthologue of IFT88, continues to move along fully formed sensory cilia, and that its acute knockdown in the ciliated neurons of the adult affects sensory behaviour. We further identify DmGucy2d, the Drosophila guanylyl cyclase 2d, as a DmIFT88 cargo, whose loss also leads to defects in sensory behaviour maintenance. DmIFT88 binds to the intracellular part of DmGucy2d, which is evolutionarily conserved and mutated in several degenerative retina diseases, taking the cyclase into the cilia. Our results offer a novel mechanism for the maintenance of sensory cilia function and its potential role in human diseases.

cell biology↗

bioRxiv2020

A first-takes-all model of centriole copy number control

How cells control the numbers of its subcellular components is a fundamental question in biology. Given that biosynthetic processes are fundamentally stochastic it is utterly puzzling that some structures display no copy number variation within a cell population. Centriole biogenesis, with each centriole being duplicated once and only once per cell cycle, stands out due to its remarkable fidelity. This is a highly controlled process, which depends on low-abundance rate-limiting factors. How can exactly one centriole copy be produced given the natural variation in the concentration of these key players? Hitherto, tentative explanations of this control evoked lateral inhibition-or phase separation-like mechanisms emerging from the dynamics of these rate-limiting factors, but how centriole number is regulated remains unclear. Here, we propose a novel solution to centriole copy number control based on the assembly of a centriolar scaffold, the cartwheel. We hypothesise that once the first cartwheel is formed it continues to elongate by stacking the intermediate cartwheel building blocks that would otherwise form supernumerary structures. Using probability theory and computer simulations, we show that this mechanism may ensure formation of one and only one cartwheel over a wide range of parameter values at physiologically relevant conditions. By comparison to alternative models, we conclude that the key signatures of this novel mechanism are an increasing assembly time with cartwheel numbers and that stochasticity in cartwheel building blocks should be converted into variation in cartwheel numbers or length, both of which can be tested experimentally. Author summaryCentriole duplication stands out as a biosynthetic process of exquisite fidelity in the noisy world of the cell. Each centriole duplicates exactly once per cell cycle, such that the number of centrioles per cell shows no variance across cells, in contrast with most cellular components that show broadly distributed copy numbers. We propose a new solution to the number control problem. We show that elongation of the first cartwheel, a core centriolar structure, may sequester the building blocks necessary to assemble supernumerary centrioles. As a corollary, the variation in regulatory kinases and cartwheel components across the cell population is predicted to translate into cartwheel length variation instead of copy number variation, which is an intriguing overlooked possibility.

cell biology↗

bioRxiv2020

Patterns of selection against centrosome amplification in human cell lines

The presence of extra centrioles, or centrosome amplification, is a hallmark of cancer cells. Centriole numbers in cancer cell populations appear to be at an equilibrium maintained by centriole overproduction and selection, reminiscent of mutation-selection balance. It is not known if the interaction between centriole overproduction and selection can quantitatively explain the intra- and inter-population heterogeneity in centriole numbers. Here, we define mutation-selection-like models and employ a model selection approach to infer patterns of centriole overproduction and selection in a diverse panel of cell lines. Surprisingly, we infer strong and uniform selection against any number of extra centrioles, in most cell lines. However, we do not detect significant differences in parameter estimates between different cell lines. Finally we assess the accuracy and precision of our inference method and find that it increases non-linearly as a function of the number of sampled cells. We discuss the biological implications of our results and how our methodology can inform future experiments.

cell biology↗

bioRxiv2018

An ancestral role of pericentrin in centriole formation through SAS-6 recruitment

The centrosome is composed of two centrioles surrounded by a microtubule-nucleating pericentriolar matrix (PCM). Centrioles regulate matrix assembly. Here we ask whether the matrix also regulates centriole assembly. To define the interaction between the matrix and individual centriole components, we take advantage of a heterologous expression system using fission yeast. Importantly, its centrosome, the spindle pole body (SPB), has matrix but no centrioles. Surprisingly, we observed that the SPB can recruit several animal centriole components. Pcp1/pericentrin, a conserved matrix component that is often upregulated in cancer, recruits a critical centriole constituent, SAS-6. We further show that this novel interaction is conserved and important for centriole biogenesis and elongation in animals. We speculate that the Pcp1/pericentrin-SAS-6 interaction surface was conserved for one billion years of evolution after centriole loss in yeasts, due to its conserved binding to calmodulin. This study reveals an ancestral relationship between pericentrin and the centriole, where both regulate each other assembly, ensuring mutual localisation.\n\nShort summaryThe pericentriolar matrix (PCM) is not only important for microtubule-nucleation but also can regulate centriole biogenesis. Ito et al. reveal an ancestral interaction between the centriole protein SAS-6 and the PCM component pericentrin, which regulates centriole biogenesis and elongation.

cell biology↗

bioRxiv2018

PLK4 is a microtubule-associated protein that self assembles promoting de novo MTOC formation

Summary statementPLK4 binds to microtubules and self assembles into supramolecular assemblies that recruit tubulin and trigger de novo MTOC formation in Xenopus laevis extracts.\n\nAbstractThe centrosome is an important microtubule-organizing center (MTOCs) in animal cells and it consists of two barrel-shaped structures (centrioles), surrounded by the pericentriolar material (PCM), which nucleates microtubules. PCM components form condensates, supramolecular assemblies that concentrate microtubule nucleators. Centrosomes can form close to an existing structure (canonical duplication) or de novo. How centrosomes form de novo is not known. PLK4 is a master driver of centrosome biogenesis, which is critical to recruit several centriole components. Here, we investigate the beginning of centrosome biogenesis, taking advantage of Xenopus egg extracts, where we and others have shown that PLK4 can induce de novo MTOC formation (Eckerdt et al., 2011; Zitouni et al., 2016). Surprisingly, we observe that in vitro, PLK4 can self-assemble into supramolecular assemblies that recruit /{beta}-tubulin. In Xenopus extracts, PLK4 supramolecular assemblies additionally recruit the PLK4 substrate STIL and the microtubule nucleator, {gamma}-tubulin, and form acentriolar MTOCs de novo. The assembly of these robust microtubule asters is independent of dynein, similarly to centrosomes. We suggest a new mechanism of action for PLK4, where it forms a self-organizing catalytic scaffold that recruits centriole components, PCM factors and /{beta}-tubulin, leading to MTOC formation.

cell biology↗