TheDrosophilamyogenic inhibitorHimgene is essential for adult muscle function and muscle stem cell maintenance

Abstract

SummaryVertebrate muscle fibres have a population of Muscle Stem Cells (MuSCs), or “satellite cells”, vital to muscle growth, homeostasis and repair. InDrosophila, adult MuSCs with similar characteristics have only recently been described. This has opened up theDrosophilasystem for analysing how MuSCs operate in muscle maintenance, repair and ageing. Here we show that theHimgene is expressed in the adult muscle progenitors (AMPs), or myoblasts, that make the adultDrosophilathoracic flight and jump muscles. Notably, we also show that Him is expressed in the flight muscle MuSCs identifyingHimas only the second genetic marker of these insect MuSCs. We then exploredHimfunction.Himmutants have disrupted organisation of the thoracic jump muscle, resulting in reduced jumping ability.Himmutants also have a reduced pool of the myoblasts that will develop into the flight muscles. In the flight muscles themselves,Himmutants have an age-dependent decrease in the number of MuSCs, indicating thatHimis required for maintenance of the adult muscle stem cell population. Moreover, this decrease in MuSCs coincides with a functional effect: there is an age-dependent decline in flight ability. Overall,Himis a novel marker of theDrosophilaadult MuSC, and is required during ageing both to maintain MuSC number and flight ability.