# The Drosophila Him gene is essential for adult muscle function and muscle stem cell maintenance

## TL;DR

The Him gene is important for maintaining muscle stem cells and muscle function in adult fruit flies, and its absence leads to muscle defects and reduced flight ability.

## Contribution

Him is the first gene shown to be essential for maintaining muscle stem cells and flight ability in aging Drosophila.

## Key findings

- Him is the second marker identified for Drosophila adult flight muscle stem cells.
- Him mutants show disrupted jump muscle organization and impaired jumping ability.
- Him mutants experience age-related loss of muscle stem cells and reduced flight performance.

## Abstract

Muscle stem cells (MuSCs), or “satellite cells,” are vital for vertebrate muscle growth, homeostasis, and repair. The discovery of analogous cells in Drosophila opens experimental opportunities in this genetically tractable model. Here, we show that the myogenic inhibitor gene Him, as well as being expressed in the myoblasts that form the flight and jump muscles, is expressed in flight muscle MuSCs. This makes Him only the second marker of these insect adult MuSCs. Furthermore, Him mutants exhibit disrupted jump muscle organization, impaired jumping ability, and a reduced pool of flight muscle myoblasts. In the flight muscles themselves, Him mutants show an age-dependent decrease in MuSC number, indicating Him is required for MuSC maintenance. This decrease coincides with reduced flight performance. Thus, Him is a new marker of Drosophila adult MuSCs and is the first gene shown to be required as flies age to maintain both MuSC number and flight ability.

•The Him gene is second marker for muscle stem cells (MuSCs) in adult flight muscle•Him mutants have defective adult jump muscle structure and function•Him mutants undergo an age-dependent decrease in MuSC number•Him mutants show an age-dependent decline in flight ability

The Him gene is second marker for muscle stem cells (MuSCs) in adult flight muscle

Him mutants have defective adult jump muscle structure and function

Him mutants undergo an age-dependent decrease in MuSC number

Him mutants show an age-dependent decline in flight ability

Genetics; Cell biology