392A Poster - 04. Stem cells, regeneration and tissue injury
Thursday April 07, 2:00 PM - 4:00 PM

Authors:
Kumar Vishal; Richard Cripps

Affiliation: San Diego State University, San Diego, CA

Keywords:
p. other (Muscle stem cell); p. other (Muscle stem cell)

Indirect flight muscles (IFMs) are the largest muscles in Drosophila and are made up of hundreds of myonuclei. The generation of these giant muscles requires a large pool of wing disc associated muscle stem cells. To achieve this, there is an activation of quiescent muscle stem cells followed by a rapid scaling up of the pool in the postembryonic stages, where the number of adult muscle stem cell increases from 10-20 to 2500 within 4 days. However the factors that control activation and proliferation to form this muscle stem pool are incompletely known. The goal of this study is to examine the role of Insulin receptor/Akt/TOR signaling in the regulation of muscle stem cell. We find that blocking the components of Insulin receptor/Akt/TOR signaling results in a diminished myoblast pool. This reduction in the pool size is due to decreased muscle stem cell activation and proliferation. Disrupting the Insulin receptor/Akt/TOR signaling at initial stages of larval development results in an absence of myoblast pool activation. On the other hand, abrogating signaling in the late larval stage reduces muscle stem pool. Furthermore, our results demonstrate that the attenuation of the Insulin recptor signaling leads to complete absence of IFM formation. By contrast, activating the pathway increases the pool size and the proliferative capacity of the muscle stem cells. Finally our genetic interaction data suggests that Akt interacts with a pseudokinase Tribbles to regulate muscle stem cell population. Collectively, our studies identify a novel role for Insulin receptor/Akt/Tor signaling in the activation and proliferation of the muscle stem cell pool.