Mcidas mutant mice reveal a two-step process for the specification and differentiation of multiciliated cells in mammals

Motile cilia on multiciliated cells (MCCs) function in fluid clearance over epithelia. Studies with Xenopus embryos and individuals with the congenital respiratory disorder reduced generation of multiple motile cilia (RGMC), have implicated the nuclear protein MCIDAS (MCI), in the transcriptional regulation of MCC specification and differentiation. Recently, a paralogous protein, geminin coiled-coil domain containing (GMNC), was also shown to be required for MCC formation. Surprisingly, in contrast to the presently held view, we find that Mci mutant mice can specify MCC precursors. However, these precursors cannot produce multiple basal bodies, and mature into single ciliated cells. We identify an essential role for MCI in inducing deuterosome pathway components for the production of multiple basal bodies. Moreover, GMNC and MCI associate differentially with the cell-cycle regulators E2F4 and E2F5, which enables them to activate distinct sets of target genes (ciliary transcription factor genes versus basal body amplification genes). Our data establish a previously unrecognized two-step model for MCC development: GMNC functions in the initial step for MCC precursor specification. GMNC induces Mci expression that drives the second step of basal body production for multiciliation

Current perspectives of the signaling pathways directing neural crest induction

The neural crest is a migratory population of embryonic cells with a tremendous potential to differentiate and contribute to nearly every organ system in the adult body. Over the past two decades, an incredible amount of research has given us a reasonable understanding of how these cells are generated. Neural crest induction involves the combinatorial input of multiple signaling pathways and transcription factors, and is thought to occur in two phases from gastrulation to neurulation. In the first phase, FGF and Wnt signaling induce NC progenitors at the border of the neural plate, activating the expression of members of the Msx, Pax, and Zic families, among others. In the second phase, BMP, Wnt, and Notch signaling maintain these progenitors and bring about the expression of definitive NC markers including Snail2, FoxD3, and Sox9/10. In recent years, additional signaling molecules and modulators of these pathways have been uncovered, creating an increasingly complex regulatory network. In this work, we provide a comprehensive review of the major signaling pathways that participate in neural crest induction, with a focus on recent developments and current perspectives. We provide a simplified model of early neural crest development and stress similarities and differences between four major model organisms: Xenopus, chick, zebrafish, and mouse

Notch destabilises maternal β-catenin and restricts dorsal-anterior development in Xenopus

The blastula chordin- and noggin-expressing centre (BCNE) is the predecessor of the Spemann-Mangold's organiser and alsocontains the precursors of the brain. This signalling centre comprises animal-dorsal and marginal-dorsal cells and appears as a consequence of the nuclear accumulation of β-catenin on the dorsal side. Here, we propose a role for Notch that was not previously explored during early development in vertebrates. Notch initially destabilises β-catenin in a process that does not depend on its phosphorylation by GSK3. This is important to restrict the BCNE to its normal extent and to control the size of the brain. © 2011. Published by The Company of Biologists Ltd.Fil: Acosta , Helena. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencias; ArgentinaFil: Lopez, Silvia Liliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia ; ArgentinaFil: Revinski, Diego Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia ; ArgentinaFil: Carrasco, Andres Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia ; Argentin

Delta-Notch signaling is involved in the segregation of the three germ layers in Xenopus laevis

In vertebrates, the induction of the three germ layers (ectoderm, mesoderm and endoderm) has been extensively studied, but less is known about how they segregate. Here, we investigated whether Delta-Notch signaling is involved in this process. Activating the pathway in the marginal zone with NotchICD resulted in an expansion of endodermal and neural ectoderm precursors, leaving a thinner mesodermal ring around the blastopore at gastrula stage, when germ layers are segregated. On the other hand, when the pathway was blocked with Delta-1STU or with an antisense morpholino oligonucleotide against Notch, the pan-mesodermal brachyury (bra) domain was expanded and the neural border was moved animalwards. Strikingly, the suprablastoporal endoderm was either expanded when Delta-1 signaling was blocked, or reduced after the general knock-down of Notch. In addition, either activating or blocking the pathway delays the blastopore closure. We conclude that the process of delimiting the three germ layers requires Notch signaling, which may be finely regulated by ligands and/or involve non-canonical components of the pathway. Moreover, Notch activity must be modulated at appropriate levels during this process in order to keep normal morphogenetic movements during gastrulation.Fil: Revinski, Diego Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Paganelli, Alejandra Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Carrasco, Andres Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Lopez, Silvia Liliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; Argentin

miR-34/449 control apical actin network formation during multiciliogenesis through small GTPase pathways

International audienceVertebrate multiciliated cells (MCCs) contribute to fluid propulsion in several biological processes. We previously showed that microRNAs of the miR-34/449 family trigger MCC differentiation by repressing cell cycle genes and the Notch pathway. Here, using human and Xenopus MCCs, we show that beyond this initial step, miR-34/449 later promote the assembly of an apical actin network, required for proper basal bodies anchoring. Identification of miR-34/449 targets related to small GTPase pathways led us to characterize R-Ras as a key regulator of this process. Protection of RRAS messenger RNA against miR-34/449 binding impairs actin cap formation and multiciliogenesis, despite a still active RhoA. We propose that miR-34/449 also promote relocalization of the actin binding protein Filamin-A, a known RRAS interactor, near basal bodies in MCCs. Our study illustrates the intricate role played by miR-34/449 in coordinating several steps of a complex differentiation programme by regulating distinct signalling pathways

ECT2 associated to PRICKLE1 are poor-prognosis markers in triple-negative breast cancer

International audienceTriple-negative breast cancers (TNBC) are poor-prognosis tumours candidate to chemotherapy as only systemic treatment. We previously found that PRICKLE1, a prometastatic protein involved in planar cell polarity, is upregulated in TNBC. We investigated the protein complex associated with PRICKLE1 in TNBC to identify proteins possibly involved in metastatic dissemination, which might provide new prognostic and/or therapeutic targets

Notch1 is asymmetrically distributed from the beginning of embryogenesis and controls the ventral center

Based on functional evidence, we have previously demonstrated that early ventral Notch1 activity restricts dorsoanterior development in Xenopus. We found that Notch1 has ventralizing properties and abolishes the dorsalizing activity of β-catenin by reducing its steady state levels, in a process that does not require β-catenin phosphorylation by glycogen synthase kinase 3β. In the present work, we demonstrate that Notch1 mRNA and protein are enriched in the ventral region from the beginning of embryogenesis in Xenopus. This is the earliest sign of ventral development, preceding the localized expression of wnt8a, bmp4 and Ventx genes in the ventral center and the dorsal accumulation of nuclear β-catenin. Knockdown experiments indicate that Notch1 is necessary for the normal expression of genes essential for ventral-posterior development. These results indicate that during early embryogenesis ventrally located Notch1 promotes the development of the ventral center. Together with our previous evidence, these results suggest that ventral enrichment of Notch1 underlies the process by which Notch1 participates in restricting nuclear accumulation of β-catenin to the dorsal side.Fil: Castro Colabianchi, Aitana Manuela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Revinski, Diego Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; Argentina. Aix Marseille Université, CNRS, IBDM; France; ArgentinaFil: Encinas, Paula Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Baez, María Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Monti, Renato José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Rodríguez Abinal, Mateo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; ArgentinaFil: Kodjabachian, Laurent. Aix Marseille Université, CNRS, IBDM; France; ArgentinaFil: Franchini, Lucia Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lopez, Silvia Liliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia "Prof. Eduardo de Robertis". Universidad de Buenos Aires. Facultad de Medicina. Instituto de Biología Celular y Neurociencia; Argentin

CDC20B is required for deuterosome-mediated centriole production in 1 multiciliated cells

International audienceMulticiliated cells (MCCs) harbor dozens to hundreds of motile cilia, which generate hydrodynamic forces important in animal physiology. In vertebrates, MCC differentiation involves massive centriole production by poorly characterized structures called deuterosomes. Here, single-cell RNA sequencing reveals that human deuterosome stage MCCs are characterized by the expression of many cell cycle-related genes. We further investigated the uncharacterized vertebrate-specific cell division cycle 20B (CDC20B) gene, which hosts microRNA-449abc. We show that CDC20B protein associates to deuterosomes and is required for centriole release and subsequent cilia production in mouse and Xenopus MCCs. CDC20B interacts with PLK1, a kinase known to coordinate centriole disengagement with the protease Separase in mitotic cells. Strikingly, over-expression of Separase rescues centriole disengagement and cilia production in CDC20B-deficient MCCs. This work reveals the shaping of deuterosome-mediated centriole production in vertebrate MCCs, by adaptation of canonical and recently evolved cell cycle-related molecules