10 research outputs found
A Novel Role for Dbx1-Derived Cajal-Retzius Cells in Early Regionalization of the Cerebral Cortical Neuroepithelium
Patterning of the cerebral cortex during embryogenesis depends not only on passive diffusion of morphogens but also on signal delivery by Cajal-Retzius neurons that migrate over long distances
Cractérisation et fonction des cellulesde Cajal-Retzius dérivées de Dbx1 lors du développement du cortex cérébral
Notre premier travail porte sur la thĂ©orie des classes de Chern pour les faisceaux cohĂ©rents. Sur les variĂ©tĂ©s projectives, elle est complĂštement achevĂ©e dans les anneaux de Chow grĂące Ă l'existence de rĂ©solutions globales localement libres et se ramĂšne formellement Ă la thĂ©orie pour les fibrĂ©s. Un rĂ©sultat de Voisin montre que ce rĂ©solutions n'existent pas toujours sur des variĂ©tĂ©s complexes compactes gĂ©nĂ©rales. Nous construisons ici par rĂ©currence sur la dimension de la variĂ©tĂ© de base des classes de Chern en cohomologie de Deligne rationnelle pour les faisceaux cohĂ©rents en imposant la formule de Grothendieck-Riemann-Roch pour les immersions et en utilisant des mĂ©thodes de dĂ©vissage. Ces classes sont les seules Ă vĂ©rifier la formule de fonctorialitĂ© par pull-back, la formule de Whitney et GRR pour les immersions; elles coĂŻncident donc avec les classes topologiques et les classes d'Atiyah. Elles vĂ©rifient aussi GRR pour les morphismes projectifs. Notre second travail est l'Ă©tude des schĂ©mas de Hilbert ponctuels d'une variĂ©tĂ© symplectique ou presque-complexe de dimension 4. Ils ont Ă©tĂ© construits par Voisin et gĂ©nĂ©ralisent les schĂ©mas de Hilbert connus pour les surfaces projectives. En utilisant les structures complexes relatives intĂ©grables introduites dans la construction de Voisin, nous pouvons Ă©tendre au cas presque-complexe ou symplectique la thĂ©orie classique. Nous calculons les nombres de Betti, nous construisons les opĂ©rateurs de Nakajima, nous Ă©tudions l'anneau de cohomologie de ces schĂ©mas de Hilbert et nous prouvons dans ce contexte un cas particulier de la conjecture de la rĂ©solution crĂȘpante de Ruan.PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
A wide diversity of cortical GABAergic interneurons derives from the embryonic preoptic area
GABA-containing (GABAergic) interneurons comprise a very heterogeneousgroupof cells that are crucial for cortical function. Different classes of interneurons specialize in targeting specific subcellular domains of excitatory pyramidal cells or other interneurons, which provides cortical circuits with an enormous capability for information processing. As in other regions of the CNS, cortical interneuron diversity is thought to emerge from the genetic specification of different groups of progenitor cells within the subpallium. Most cortical interneurons originate from twomainregions, the medial and the caudal ganglionic eminences(MGEand CGE, respectively). In addition, it has beenshownthat progenitors in the embryonic preoptic area (POA) also produce a small population of cortical GABAergic interneurons. Here, we show that the contribution of the POA to the complement of cortical GABAergic interneurons is larger than previously believed. Using genetic fate mapping and in utero transplantation experiments, we demonstrate that Dbx1-expressing progenitor cells in the POA give rise to a small but highly diverse cohort of cortical interneurons, with some neurochemical and electrophysiological characteristics that were previously attributed to MGE- or CGEderived interneurons. There are, however, some features that seem to distinguish POA-derived interneurons from MGE- or CGE-derived cells, such as their preferential laminar location. These results indicate that themechanismscontrolling the specification of different classes of cortical interneurons might be more complex than previously expected. Together with earlier findings, our results also suggest that the POA generates nearly 10% of the GABAergic interneurons in the cerebral cortex of the mouse. Ă© 2011 the authors.This work was supported by grants from the European Commission through STREP contract number 005139 (INTERDEVO) to O.M. and A.P.; the Spanish Ministry of Science and Innovation SAF2008-00770, SAF2009-08049-E, and CONSOLIDER CSD2007-00023 to O.M.; and Fondation pour le Recherche MĂ©dicale (INE20060306503) and Ville de Paris (2006 ASES 102) to A.P. D.G. was recipient of a Marie Curie International Incoming Fellowship.Peer Reviewe
A novel transient glutamatergic population migrating from the pallial-subpallial boundary contributes to neocortical development.
International audienceThe generation of a precise number of neural cells and the determination of their laminar fate are tightly controlled processes during development of the cerebral cortex. Using genetic tracing in mice, we have identified a population of glutamatergic neurons generated by Dbx1-expressing progenitors at the pallial-subpallial boundary predominantly at embryonic day 12.5 (E12.5) and subsequent to Cajal-Retzius cells. We show that these neurons migrate tangentially to populate the cortical plate (CP) at all rostrocaudal and mediolateral levels by E14.5. At birth, they homogeneously populate cortical areas and represent <5% of cortical cells. However, they are distributed into neocortical layers according to their birthdates and express the corresponding markers of glutamatergic differentiation (Tbr1, ER81, Cux2, Ctip2). Notably, this population dies massively by apoptosis at the completion of corticogenesis and represents 50% of dying neurons in the postnatal day 0 cortex. Specific genetic ablation of these transient Dbx1-derived CP neurons leads to a 20% decrease in neocortical cell numbers in perinatal animals. Our results show that a previously unidentified transient population of glutamatergic neurons migrates from extraneocortical regions over long distance from their generation site and participates in neocortical radial growth in a non-cell-autonomous manner
Enhanced Abventricular Proliferation Compensates Cell Death in the Embryonic Cerebral Cortex
International audienc
Loss of Pla2r1 decreases cellular senescence and ageârelated alterations caused by aging and Western diets
International audienceCellular senescence is induced by many stresses including telomere shortening, DNA damage, oxidative, or metabolic stresses. Senescent cells are stably cell cycle arrested and they secrete many factors including cytokines and chemokines. Accumulation of senescent cells promotes many ageârelated alterations and diseases. In this study, we investigated the role of the proâsenescent phospholipase A2 receptor 1 (PLA2R1) in regulating some ageârelated alterations in old mice and in mice subjected to a Western diet, whereas aged wildâtype mice displayed a decreased ability to regulate their glycemia during glucose and insulin tolerance tests, aged Pla2r1 knockout (KO) mice efficiently regulated their glycemia and displayed fewer signs of aging. Loss of Pla2r1 was also found protective against the deleterious effects of a Western diet. Moreover, these Pla2r1 KO mice were partially protected from dietâinduced senescent cell accumulation, steatosis, and fibrosis. Together these results support that Pla2r1 drives several ageârelated alterations, especially in the liver, arising during aging or through a Western diet
Multiple origins of Cajal-Retzius cells at the borders of the developing pallium
Cajal-Retzius cells are critical in cortical lamination, but very little is known about their origin and development. The homeodomain transcription factor Dbx1 is expressed in restricted progenitor domains of the developing pallium: the ventral pallium (VP) and the septum. Using genetic tracing and ablation experiments in mice, we show that two subpopulations of Reelin(+) Cajal-Retzius cells are generated from Dbx1-expressing progenitors. VP- and septum-derived Reelin(+) neurons differ in their onset of appearance, migration routes, destination and expression of molecular markers. Together with reported data supporting the generation of Reelin(+) cells in the cortical hem, our results show that Cajal-Retzius cells are generated at least at three focal sites at the borders of the developing pallium and are redistributed by tangential migration. Our data also strongly suggest that distinct Cajal-Retzius subtypes exist and that their presence in different territories of the developing cortex might contribute to region-specific properties