Séminaire de Christophe Jagla sur "Developmental programs controlling diversification of muscle types and behavior of muscle stem cells in Drosophila"
Lundi 19 mai 2014 à 11h00 à l'Ecole normale Supérieure de Lyon (Site Monod, Salle des Thèses).
Abstract: In all metazoan organisms, the diversification of cell types involves determination of cell fates and subsequent execution of specific differentiation programs. During Drosophila myogenesis, identity genes specify the fates of founder myoblasts, from which derive all individual larval muscles and stem cell-like Adult Muscle Precursors (AMPs). Here, to understand how cell fate information residing within founders is translated during differentiation, we focus on three identity genes, eve, lb and slou and how they control the size of individual muscles by regulating the number of fusion events. We also use Drosophila model to follow specification and in vivo behavior of AMP cells. We report that emerging AMPs display homing behavior, and that muscles act as their niche by protecting dormant AMPs from apoptosis. We also demonstrate that muscles send local inductive dIlp6 signals, which at the end of second larval instar activate proliferation of AMPs. Unexpectedly, genetic rescue experiments reveal that the Insulin pathway acts upstream of Notch, and positively regulates proliferation of AMPs via dMyc. Thus we provide evidence for a muscle type-specific developmental fusion programs and for muscle-driven Insulin-Notch-Myc cascade setting the activated state of AMPs in Drosophila.
LMBC UMR 5239
ENS-Lyon, site Monod
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Lyon cedex 07 FRANCE
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