The Experts below are selected from a list of 336 Experts worldwide ranked by ideXlab platform

Alice Meunier - One of the best experts on this subject based on the ideXlab platform.

  • Dynamics of centriole amplification in centrosome-depleted brain multiciliated progenitors
    Scientific Reports, 2019
    Co-Authors: Olivier Mercey, Marion Faucourt, Alexia Mahuzier, Adel Al Jord, Nathalie Spassky, Philippe Rostaing, Aurélien Fortoul, Amelie-rose Boudjema, Alice Meunier
    Abstract:

    Reproductive and respiratory organs, along with brain ventricles, are lined by multiciliated epithelial cells (MCC) that generate cilia-powered fluid flows. MCC hijack the centrosome duplication pathway to form hundreds of centrioles and nucleate motile cilia. In these cells, the large majority of Procentrioles are formed associated with partially characterized organelles called deuterosomes. We recently challenged the paradigm that deuterosomes and Procentrioles are formed de novo by providing data, in brain MCC, suggesting that they are nucleated from the pre-existing centrosomal younger centriole. However, the origin of deuterosomes and Procentrioles is still under debate. Here, we further question centrosome importance for deuterosome and centriole amplification. First, we provide additional data confirming that centriole amplification occurs sequentially from the centrosomal region, and that the first Procentriole-loaded deuterosomes are associated with the daughter centriole or in the centrosomal centriole vicinity. Then, to further test the requirement of the centrosome in deuterosome and centriole formation, we depleted centrosomal centrioles using a Plk4 inhibitor. We reveal unexpected limited consequences in deuterosome/centriole number in absence of centrosomal centrioles. Notably, in absence of the daughter centriole only, deuterosomes are not seen associated with the mother centriole. In absence of both centrosomal centrioles, Procentrioles are still amplified sequentially and with no apparent structural defects. They seem to arise from a focal region, characterized by microtubule convergence and pericentriolar material (PCM) assembly. The relevance of deuterosome association with the daughter centriole as well as the role of the PCM in the focal and sequential genesis of centrioles in absence of centrosomal centrioles are discussed.

  • Dynamics of centriole amplification in centrosome-depleted brain multiciliated progenitors
    2018
    Co-Authors: Olivier Mercey, Marion Faucourt, Alexia Mahuzier, Adel Al Jord, Nathalie Spassky, Philippe Rostaing, Aurélien Fortoul, Amelie-rose Boudjema, Alice Meunier
    Abstract:

    Centrioles are essential microtubule-based organelles organizing cilia and centrosomes. Their mode of biogenesis is semi-conservative: each pre-existing centriole scaffolds the formation of a new one, a process coordinated with the cell cycle. By contrast, multiciliated progenitors with two centrosomal centrioles massively amplify centrioles to support the nucleation of hundred of motile cilia and transport vital fluids. This occurs through cell type-specific organelles called deuterosomes, composed of centrosome-related elements, and is regulated by the cell cycle machinery. Deuterosome-dependent centriole amplification was proposed for decades to occur de novo, i.e. independently from pre-existing centrioles. Challenging this hypothesis, we recently reported an accumulation of Procentriole and deuterosome precursors at the centrosomal daughter centriole during centriole amplification in brain multiciliated cells. Here we further investigate the relationship between the centrosome and the dynamic of centriole amplification by (i) characterizing the centrosome behavior during the centriole amplification dynamics and (ii) assessing the dynamics of amplification in centrosome-depleted cells. Surprisingly, although our data strengthen the centrosomal origin of amplified centrioles, we show limited consequences in deuterosome/centriole number when we deplete centrosomal centrioles. Interestingly, in absence of centrosomal centrioles, Procentrioles are still amplified sequentially from a single focal region, characterized by microtubule convergence and pericentriolar material (PCM) self-assembly. The relevance of deuterosome association with the daughter centriole as well as the role of the PCM in the focal and sequential genesis of centrioles in absence of centrosomal centrioles are discussed.

  • centriole amplification by mother and daughter centrioles differs in multiciliated cells
    Nature, 2014
    Co-Authors: Adel Al Jord, Nathalie Delgehyr, Marion Faucourt, Anne-iris Lemaître, Nathalie Spassky, Alice Meunier
    Abstract:

    The semi-conservative centrosome duplication in cycling cells gives rise to a centrosome composed of a mother and a newly formed daughter centriole. Both centrioles are regarded as equivalent in their ability to form new centrioles and their symmetric duplication is crucial for cell division homeostasis. Multiciliated cells do not use the archetypal duplication program and instead form more than a hundred centrioles that are required for the growth of motile cilia and the efficient propelling of physiological fluids. The majority of these new centrioles are thought to appear de novo, that is, independently from the centrosome, around electron-dense structures called deuterosomes. Their origin remains unknown. Using live imaging combined with correlative super-resolution light and electron microscopy, we show that all new centrioles derive from the pre-existing progenitor cell centrosome through multiple rounds of Procentriole seeding. Moreover, we establish that only the daughter centrosomal centriole contributes to deuterosome formation, and thus to over ninety per cent of the final centriole population. This unexpected centriolar asymmetry grants new perspectives when studying cilia-related diseases and pathological centriole amplification observed in cycling cells and associated with microcephaly and cancer.

  • Centriole amplification by mother and daughter centrioles differs in multiciliated cells
    Nature, 2014
    Co-Authors: Adel Al Jord, Nathalie Delgehyr, Marion Faucourt, Anne-iris Lemaître, Nathalie Spassky, Alice Meunier
    Abstract:

    Using advanced microscopy techniques, the process of centriole amplification in multiciliated cells is explored, and the daughter centriole identified as the primary nucleation site of more than 90% of the new centrioles, contesting existing de novo theories of centriolar amplification and highlighting a new centrosome asymmetry. Cells that undergo division contain two centrioles, mother and the daughter, packaged into a centrosome. Mother and daughter centrioles are thought to have the same capacity to form new centrioles when cells divide. By contrast, multiciliated cells, which propel physiological fluids and are essential for health, contain as many as 200 centrioles, each one giving rise to a motile cilium, with new centrioles arising de novo independent of a centriole template. Studying multiciliated cells of the mouse brain, Alice Meunier and colleagues contest these long-held beliefs. Using state-of-the-art microscopy techniques, they document the process of centriole amplification in action, and find that the daughter centriole is the primary nucleation site for more than 90% of the new centrioles. The semi-conservative centrosome duplication in cycling cells gives rise to a centrosome composed of a mother and a newly formed daughter centriole1. Both centrioles are regarded as equivalent in their ability to form new centrioles and their symmetric duplication is crucial for cell division homeostasis2,3,4. Multiciliated cells do not use the archetypal duplication program and instead form more than a hundred centrioles that are required for the growth of motile cilia and the efficient propelling of physiological fluids5. The majority of these new centrioles are thought to appear de novo, that is, independently from the centrosome, around electron-dense structures called deuterosomes6,7,8. Their origin remains unknown. Using live imaging combined with correlative super-resolution light and electron microscopy, we show that all new centrioles derive from the pre-existing progenitor cell centrosome through multiple rounds of Procentriole seeding. Moreover, we establish that only the daughter centrosomal centriole contributes to deuterosome formation, and thus to over ninety per cent of the final centriole population. This unexpected centriolar asymmetry grants new perspectives when studying cilia-related diseases5,9 and pathological centriole amplification observed in cycling cells and associated with microcephaly and cancer2,3,4,10.

Pierre Gonczy - One of the best experts on this subject based on the ideXlab platform.

  • selective chemical crosslinking reveals a cep57 cep63 cep152 centrosomal complex
    Current Biology, 2013
    Co-Authors: Gražvydas Lukinavicius, Darja Lavogina, Meritxell Orpinell, Keitaro Umezawa, Luc Reymond, Nathalie Garin, Pierre Gonczy, Kai Johnsson
    Abstract:

    The centrosome functions as the main microtubule-organizing center of animal cells and is crucial for several fundamental cellular processes. Abnormalities in centrosome number and composition correlate with tumor progression and other diseases. Although proteomic studies have identified many centrosomal proteins, their interactions are incompletely characterized. The lack of information on the precise localization and interaction partners for many centrosomal proteins precludes comprehensive understanding of centrosome biology. Here, we utilize a combination of selective chemical crosslinking and superresolution microscopy to reveal novel functional interactions among a set of 31 centrosomal proteins. We reveal that Cep57, Cep63, and Cep152 are parts of a ring-like complex localizing around the proximal end of centrioles. Furthermore, we identify that STIL, together with HsSAS-6, resides at the proximal end of the Procentriole, where the cartwheel is located. Our studies also reveal that the known interactors Cep152 and Plk4 reside in two separable structures, suggesting that the kinase Plk4 contacts its substrate Cep152 only transiently, at the centrosome or within the cytoplasm. Our findings provide novel insights into protein interactions critical for centrosome biology and establish a toolbox for future studies of centrosomal proteins.

  • overly long centrioles and defective cell division upon excess of the sas 4 related protein cpap
    Current Biology, 2009
    Co-Authors: Gregor Kohlmaier, Alexey Khodjakov, Jadranka Loncarek, Xing Meng, Bruce F Mcewen, Mette M Mogensen, Alexander Spektor, Brian David Dynlacht, Pierre Gonczy
    Abstract:

    The centrosome is the principal microtubule organizing center (MTOC) of animal cells [1]. Accurate centrosome duplication is fundamental for genome integrity and entails the formation of one Procentriole next to each existing centriole, once per cell cycle. The Procentriole then elongates to eventually reach the same size as the centriole. The mechanisms that govern elongation of the centriolar cylinder and their potential relevance for cell division are not known. Here, we show that the SAS-4-related protein CPAP [2] is required for centrosome duplication in cycling human cells. Furthermore, we demonstrate that CPAP overexpression results in the formation of abnormally long centrioles. This also promotes formation of more than one Procentriole in the vicinity of such overly long centrioles, eventually resulting in the presence of supernumerary MTOCs. This in turn leads to multipolar spindle assembly and cytokinesis defects. Overall, our findings suggest that centriole length must be carefully regulated to restrict Procentriole number and thus ensure accurate cell division.

  • regulated hssas 6 levels ensure formation of a single Procentriole per centriole during the centrosome duplication cycle
    Developmental Cell, 2007
    Co-Authors: Petr Strnad, Ursula Euteneuer, Alexey Khodjakov, Sebastian A Leidel, Tatiana Vinogradova, Pierre Gonczy
    Abstract:

    Summary Centrosome duplication involves the formation of a single Procentriole next to each centriole, once per cell cycle. The mechanisms governing Procentriole formation and those restricting its occurrence to one event per centriole are poorly understood. Here, we show that HsSAS-6 is necessary for Procentriole formation and that it localizes asymmetrically next to the centriole at the onset of Procentriole formation. HsSAS-6 levels oscillate during the cell cycle, with the protein being degraded in mitosis and starting to accumulate again at the end of the following G1. Our findings indicate that APC Cdh1 targets HsSAS-6 for degradation by the 26S proteasome. Importantly, we demonstrate that increased HsSAS-6 levels promote formation of more than one Procentriole per centriole. Therefore, regulated HsSAS-6 levels normally ensure that each centriole seeds the formation of a single Procentriole per cell cycle, thus playing a fundamental role in driving the centrosome duplication cycle and ensuring genome integrity.

Daiju Kitagawa - One of the best experts on this subject based on the ideXlab platform.

  • self organization of plk4 regulates symmetry breaking in centriole duplication
    Nature Communications, 2019
    Co-Authors: Shohei Yamamoto, Daiju Kitagawa
    Abstract:

    During centriole duplication, a single daughter centriole is formed next to the mother centriole. The molecular mechanism that determines a single duplication site remains a long-standing question. Here, we show that intrinsic self-organization of Plk4 is implicated in symmetry breaking in the process of centriole duplication. We demonstrate that Plk4 has an ability to phase-separate into condensates via an intrinsically disordered linker and that the condensation properties of Plk4 are regulated by autophosphorylation. Consistently, the dissociation dynamics of centriolar Plk4 are controlled by autophosphorylation. We further found that autophosphorylated Plk4 is already distributed as a single focus around the mother centriole before the initiation of Procentriole formation, and is subsequently targeted for STIL-HsSAS6 loading. Perturbation of Plk4 self-organization affects the asymmetry of centriolar Plk4 distribution and proper centriole duplication. Overall, we propose that the spatial pattern formation of Plk4 is a determinant of a single duplication site per mother centriole.

  • self organization of plk4 regulates symmetry breaking in centriole duplication
    bioRxiv, 2018
    Co-Authors: Shohei Yamamoto, Daiju Kitagawa
    Abstract:

    During centriole duplication, a single daughter centriole is formed near the mother centriole. The mechanism that determines a single duplication site is unknown. Here, we demonstrate that intrinsic self-organization of Plk4 underlies symmetry breaking in centriole duplication. We show that in its nonphosphorylated state, Plk4 preferentially self-assembles via a disordered linker and that this self-assembly is prevented by autophosphorylation. Consistently, the dissociation dynamics of centriolar Plk4 are controlled by autophosphorylation. We further found that autophophorylated Plk4 is localized as a single focus around the mother centriole before Procentriole formation, and is subsequently targeted for STIL-HsSAS6 loading. Perturbing Plk4 self-organization affects the asymmetry of centriolar Plk4 distribution and centriole duplication. We propose that the spatial patterning of Plk4 directs a single duplication site per mother centriole.

  • Bimodal Binding of STIL to Plk4 Controls Proper Centriole Copy Number
    Elsevier, 2018
    Co-Authors: Midori Ohta, Satoko Yoshiba, Yuka Nozaki, Tomoko Ashikawa, Koki Watanabe, Akatsuki Kimura, Daiju Kitagawa
    Abstract:

    Summary: The number of centrioles is tightly controlled to ensure bipolar spindle assembly, which is a prerequisite to maintain genome integrity. However, our understanding of the fundamental principle that governs the formation of a single Procentriole per parental centriole is incomplete. Here, we show that the local restriction of Plk4, a master regulator of the Procentriole formation, is achieved by a bimodal interaction of STIL with Plk4. We demonstrate that the conserved short coiled-coil region of STIL binds to and protects Plk4 from protein degradation at the site of Procentriole formation. On the other hand, the conserved C-terminal region of STIL named truncated in microcephaly (TIM) domain promotes autophosphorylation and degradation of adjacent Plk4 by the direct interaction. Thus, we propose that positive and negative regulation based on the bimodal binding of Plk4 and STIL ensures the formation of a single Procentriole per parental centriole. : Ohta et al. show that Plk4 asymmetrically localizes around mother centrioles before the onset of Procentriole formation. Furthermore, they reveal that bimodal binding of STIL to Plk4 restricts Plk4 localization at a single site and thus ensures formation of a single Procentriole per mother centriole. Keywords: cell division, centrosome, centriole duplication, Plk4, STI

  • direct interaction of plk4 with stil ensures formation of a single Procentriole per parental centriole
    Nature Communications, 2014
    Co-Authors: Midori Ohta, Yuka Nozaki, Tomoko Ashikawa, Hiroko Kozukahata, Hidemasa Goto, Masaki Inagaki, Masaaki Oyama, Daiju Kitagawa
    Abstract:

    Formation of one Procentriole next to each pre-existing centriole is essential for centrosome duplication, robust bipolar spindle assembly and maintenance of genome integrity. However, the mechanisms maintaining strict control over centriole copy number are incompletely understood. Here we show that Plk4 and STIL, the key regulators of centriole formation, form a protein complex that provides a scaffold for recruiting HsSAS-6, a major component of the centriolar cartwheel, at the onset of Procentriole formation. Furthermore, we demonstrate that phosphorylation of STIL by Plk4 facilitates the STIL/HsSAS-6 interaction and centriolar loading of HsSAS-6. We also provide evidence that negative feedback by centriolar STIL regulates bimodal centriolar distribution of Plk4 and seemingly restricts occurrence of Procentriole formation to one site on each parental centriole. Overall, these findings suggest a mechanism whereby coordinated action of three critical factors ensures formation of a single Procentriole per parental centriole.

Andrew J Holland - One of the best experts on this subject based on the ideXlab platform.

  • plk4 promotes centriole duplication by phosphorylating stil to link the Procentriole cartwheel to the microtubule wall
    eLife, 2019
    Co-Authors: Tyler C Moyer, Andrew J Holland
    Abstract:

    A cell’s DNA is the chemical instruction manual for everything it does. Each cell in our bodies contains over two meters of DNA, which is divided into 46 packages of information called chromosomes. When the body needs to make more cells, for example during growth or repair, existing cells divide in two in order to replicate themselves. This means that they also need to copy all of their DNA and then deliver identical sets of chromosomes to each new cell. Animal cells use structures called centrioles to help them divide their sets of chromosomes accurately. When cells are about to divide, they make a new set of centrioles by assembling a variety of proteins. This assembly process must be carefully controlled; if too many or too few centrioles are built, cell division errors can occur that lead to the generation of new cells with abnormal numbers of chromosomes. The enzyme PLK4 helps to assemble centrioles, but its exact role in the construction process has remained largely unknown. For example, how it might modify different components of the centriole, and why this matters, is poorly understood. By performing cell biological and biochemical experiments using human cells, Moyer and Holland show that PLK4 interacts with a protein called STIL that is found in the central part of the centriole. The modification of STIL at a specific location by PLK4 was needed to link it to another protein in the outer wall of the centriole, and was also necessary for the cells to build new centrioles. Cells in which PLK4 was unable to modify STIL had too few centrioles when they were beginning to divide. Testing the activity of PLK4 in fruit flies revealed that it plays a similar role as in human cells. This suggests that the modification of STIL by PLK4 is important for normal cell division across different species. The results presented by Moyer and Holland help us to understand how dividing cells build the complex machinery that enables them to pass on their genetic material accurately. Future work that builds on these findings could provide insight into human diseases, such as brain development disorders and cancer, where centrioles are either defective or present in the wrong number.

  • autoamplification and competition drive symmetry breaking initiation of centriole duplication by the plk4 stil network
    bioRxiv, 2018
    Co-Authors: Marcin Leda, Andrew J Holland, Andrew B Goryachev
    Abstract:

    Symmetry breaking, a central principle of physics, has been hailed as the driver of self-organization in biological systems in general and biogenesis of cellular organelles in particular, but the molecular mechanisms of symmetry breaking only begin to become understood. Centrioles, the structural cores of centrosomes and cilia, must duplicate every cell cycle to ensure their faithful inheritance through cellular divisions. Work in model organisms identified conserved proteins required for centriole duplication and found that altering their abundance affects centriole number. However, the biophysical principles that ensure that, under physiological conditions, only a single Procentriole is produced on each mother centriole remain enigmatic. Here we propose a mechanistic biophysical model for the initiation of Procentriole formation in mammalian cells. We posit that interactions between the master regulatory kinase PLK4 and its activator-substrate STIL form the basis of the Procentriole initiation network. The model faithfully recapitulates the experimentally observed transition from PLK4 uniformly distributed around the mother centriole, the "ring", to a unique PLK4 focus, the "spot", that triggers the assembly of a new Procentriole. This symmetry breaking requires a dual positive feedback based on autocatalytic activation of PLK4 and enhanced centriolar anchoring of PLK4-STIL complexes by phosphorylated STIL. We find that, contrary to previous proposals, in situ degradation of active PLK4 is insufficient to break symmetry. Instead, the model predicts that competition between transient PLK4 activity maxima for PLK4-STIL complexes explains both the instability of the PLK4 ring and formation of the unique PLK4 spot. In the model, strong competition at physiologically normal parameters robustly produces a single Procentriole, while increasing overexpression of PLK4 and STIL weakens the competition and causes progressive addition of Procentrioles in agreement with experimental observations.

  • autoamplification and competition drive symmetry breaking initiation of centriole duplication by the plk4 stil network
    Unknown Journal, 2018
    Co-Authors: Marcin Leda, Andrew J Holland, Andrew B Goryachev
    Abstract:

    Summary Centrioles, the cores of centrosomes and cilia, duplicate every cell cycle to ensure their faithful inheritance. How only a single Procentriole is produced on each mother centriole remains enigmatic. We propose the first mechanistic biophysical model for Procentriole initiation which posits that interactions between kinase PLK4 and its activator-substrate STIL are central for Procentriole initiation. The model recapitulates the transition from a uniform “ring” of PLK4 surrounding the mother centriole to a single PLK4 “spot” that initiates Procentriole assembly. This symmetry breaking requires autocatalytic activation of PLK4 and enhanced centriolar anchoring of PLK4 by phosphorylated STIL. We find that in situ degradation of active PLK4 cannot break symmetry. The model predicts that competition between transient PLK4 activity maxima for PLK4-STIL complexes destabilizes the PLK4 ring and produces instead a single PLK4 spot. Weakening of competition by overexpression of PLK4 and STIL causes progressive addition of supernumerary Procentrioles, as observed experimentally.

  • autoamplification and competition drive symmetry breaking initiation of centriole duplication by the plk4 stil network
    arXiv: Subcellular Processes, 2018
    Co-Authors: Marcin Leda, Andrew J Holland, Andrew B Goryachev
    Abstract:

    Symmetry breaking, a central principle of physics, has been hailed as the driver of self-organization in biological systems in general and biogenesis of cellular organelles in particular, but the molecular mechanisms of symmetry breaking only begin to become understood. Centrioles, the structural cores of centrosomes and cilia, must duplicate every cell cycle to ensure their faithful inheritance through cellular divisions. Work in model organisms identified conserved proteins required for centriole duplication and found that altering their abundance affects centriole number. However, the biophysical principles that ensure that, under physiological conditions, only a single Procentriole is produced on each mother centriole remain enigmatic. Here we propose a mechanistic biophysical model for the initiation of Procentriole formation in mammalian cells. The model faithfully recapitulates the experimentally observed transition from PLK4 uniformly distributed around the mother centriole, the "ring", to a unique PLK4 focus, the "spot", that triggers the assembly of a new Procentriole. This symmetry breaking requires a dual positive feedback based on autocatalytic activation of PLK4 and enhanced centriolar anchoring of PLK4-STIL complexes by phosphorylated STIL. We find that, contrary to previous proposals, in situ degradation of active PLK4 is insufficient to break symmetry. Instead, the model predicts that competition between transient PLK4 activity maxima for PLK4-STIL complexes explains both the instability of the PLK4 ring and formation of the unique PLK4 spot. In the model, strong competition at physiologically normal parameters robustly produces a single Procentriole, while increasing overexpression of PLK4 and STIL weakens the competition and causes progressive addition of Procentrioles in agreement with experimental observations.

  • Autoamplification and Competition Drive Symmetry Breaking: Initiation of Centriole Duplication by the PLK4-STIL Network
    'Elsevier BV', 2018
    Co-Authors: Marcin Leda, Andrew J Holland, Andrew B Goryachev
    Abstract:

    Summary: Centrioles, the cores of centrosomes and cilia, duplicate every cell cycle to ensure their faithful inheritance. How only a single Procentriole is produced on each mother centriole remains enigmatic. We propose the first mechanistic biophysical model for Procentriole initiation which posits that interactions between kinase PLK4 and its activator-substrate STIL are central for Procentriole initiation. The model recapitulates the transition from a uniform “ring” of PLK4 surrounding the mother centriole to a single PLK4 “spot” that initiates Procentriole assembly. This symmetry breaking requires autocatalytic activation of PLK4 and enhanced centriolar anchoring of PLK4 by phosphorylated STIL. We find that in situ degradation of active PLK4 cannot break symmetry. The model predicts that competition between transient PLK4 activity maxima for PLK4-STIL complexes destabilizes the PLK4 ring and produces instead a single PLK4 spot. Weakening of competition by overexpression of PLK4 and STIL causes progressive addition of supernumerary Procentrioles, as observed experimentally. : Biological Sciences; Developmental Biology; In Silico Biology Subject Areas: Biological Sciences, Developmental Biology, In Silico Biolog

Tang K Tang - One of the best experts on this subject based on the ideXlab platform.

  • human microcephaly protein rttn interacts with stil and is required to build full length centrioles
    Nature Communications, 2017
    Co-Authors: Chiehju C Tang, Yinan Lin, Tang K Tang, Hsinyi Chen, Wonjing Wang
    Abstract:

    Mutations in many centriolar protein-encoding genes cause primary microcephaly. Using super-resolution and electron microscopy, we find that the human microcephaly protein, RTTN, is recruited to the proximal end of the Procentriole at early S phase, and is located at the inner luminal walls of centrioles. Further studies demonstrate that RTTN directly interacts with STIL and acts downstream of STIL-mediated centriole assembly. CRISPR/Cas9-mediated RTTN gene knockout in p53-deficient cells induce amplification of primitive Procentriole bodies that lack the distal-half centriolar proteins, POC5 and POC1B. Additional analyses show that RTTN serves as an upstream effector of CEP295, which mediates the loading of POC1B and POC5 to the distal-half centrioles. Interestingly, the naturally occurring microcephaly-associated mutant, RTTN (A578P), shows a low affinity for STIL binding and blocks centriole assembly. These findings reveal that RTTN contributes to building full-length centrioles and illuminate the molecular mechanism through which the RTTN (A578P) mutation causes primary microcephaly. Mutations in many centriolar protein-encoding genes cause primary microcephaly. Here the authors show that human microcephaly protein RTTN directly interacts with STIL and acts downstream of STIL-mediated centriole assembly, contributing to building full-length centrioles

  • the human microcephaly protein stil interacts with cpap and is required for Procentriole formation
    The EMBO Journal, 2011
    Co-Authors: Chiehju C Tang, Shinyi Lin, Wenbin Hsu, Yinan Lin, Yuchih Lin, Chingwen Chang, Tang K Tang
    Abstract:

    Centriole duplication involves the growth of a Procentriole next to the parental centriole. Mutations in STIL and CPAP/CENPJ cause primary microcephaly (MCPH). Here, we show that human STIL has an asymmetric localization to the daughter centriole and is required for Procentriole formation. STIL levels oscillate during the cell cycle. Interestingly, STIL interacts directly with CPAP and forms a complex with hSAS6. A natural mutation of CPAP (E1235V) that causes MCPH in humans leads to significantly lower binding to STIL. Overexpression of STIL induced the formation of multiple Procentrioles around the parental centriole. STIL depletion inhibited normal centriole duplication, Plk4-induced centriole amplification, and CPAP-induced centriole elongation, and resulted in a failure to localize hSAS6 and CPAP to the base of the nascent Procentriole. Furthermore, hSAS6 depletion hindered STIL targeting to the Procentriole, implying that STIL and hSAS6 are mutually dependent for their centriolar localization. Together, our results indicate that the two MCPH-associated proteins STIL and CPAP interact with each other and are required for Procentriole formation, implying a central role of centriole biogenesis in MCPH.