Cell tracing reveals a dorsoventral lineage restriction plane in the mouse limb bud mesenchyme
Carlos G. Arques, Roisin Doohan, James Sharpe and Miguel Torres
Development 134, 3713-3722(2007) doi:10.1242/dev.02873
La technique utilisé par Arques et al. est l’illustration des possibilités ouvertes par les travaux récompensés par le prix Nobel de Physiologie et Médecine 2007.
Ici des souris knock-in sont utilisées pour étudier des champs embryonnaires des membres. Le résultat de cette étude qui pose une approche technique qui pourra être utilisée pour construire des cartographies de lignage chez les embryons, est intéressant per se, montrant une distribution clonale indépendante d’une discontinuité anatomique et dont le plan de démarcation (dorso-ventral) n’est pas en relation évidente avec un centre de signalisation.
Une première qui permet de se passer de l’utilisation de marqueurs portés par des rétrovirus et simplifie le travail en minimisant l’intervention sur l’embryon.
Regionalization of embryonic fields into independent units of growth and patterning is a widespread strategy during metazoan development. Compartments represent a particular instance of this regionalization, in which unit coherence is maintained by cell lineage restriction between adjacent regions. Lineage compartments have been described during insect and vertebrate development. Two common characteristics of the compartments described so far are their occurrence in epithelial structures and the presence of signaling regions at compartment borders. Whereas Drosophila compartmental organization represents a background subdivision of embryonic fields that is not necessarily related to anatomical structures, vertebrate compartment borders described thus far coincide with, or anticipate, anatomical or cell-type discontinuities. Here, we describe a general method for clonal analysis in the mouse and use it to determine the topology of clone distribution along the three limb axes. We identify a lineage restriction boundary at the limb mesenchyme dorsoventral border that is unrelated to any anatomical discontinuity, and whose lineage restriction border is not obviously associated with any signaling center. This restriction is the first example in vertebrates of a mechanism of primordium subdivision unrelated to anatomical boundaries. Furthermore, this is the first lineage compartment described within a mesenchymal structure in any organism, suggesting that lineage restrictions are fundamental not only for epithelial structures, but also for mesenchymal field patterning. No lineage compartmentalization was found along the proximodistal or anteroposterior axes, indicating that patterning along these axes does not involve restriction of cell dispersion at specific axial positions.
Clonal analysis, Fate maps, Vertebrate limb, Lineage compartments, Lmx1b
