# eEF1α2 is required for actin cytoskeleton homeostasis in the aging muscle

## TL;DR

The study shows that eEF1α2 helps maintain muscle structure in aging fruit flies, independent of its role in protein production.

## Contribution

The paper reveals a novel role of eEF1α2 in muscle homeostasis during aging, distinct from its known function in translation.

## Key findings

- eEF1α2 null mutants in Drosophila have thinner myofibrils in young flies, which can be rescued by eEF1α1.
- Aging eEF1α2 mutants show disrupted actin and myosin distribution without changes in protein levels.
- eEF1α1 overexpression cannot rescue the age-related muscle defects caused by eEF1α2 loss.

## Abstract

The translation elongation factor eEF1α (eukaryotic elongation factor 1α) mediates mRNA translation by delivering aminoacyl-tRNAs to ribosomes. eEF1α also has other reported roles, including the regulation of actin dynamics. However, these distinct roles of eEF1α are often challenging to uncouple and remain poorly understood in aging metazoan tissues. The genomes of mammals and Drosophila encode two eEF1α paralogs, with eEF1α1 expressed ubiquitously and eEF1α2 expression more limited to neurons and muscle cells. Here, we report that eEF1α2 plays a unique role in maintaining myofibril homeostasis during aging in Drosophila. Specifically, we generated an eEF1α2 null allele, which was viable and showed two distinct muscle phenotypes. In young flies, the mutants had thinner myofibrils in indirect flight muscles that could be rescued by expressing eEF1α1. With aging, the muscles of the mutant flies began showing abnormal distribution of actin and myosin in muscles, but without a change in actin and myosin protein levels. This age-related phenotype could not be rescued by eEF1α1 overexpression. These findings support an unconventional role of Drosophila eEF1α2 in age-related homeostasis of muscle myofibers.

Summary: Drosophila eEF1α2, a well-characterized translation elongation factor, is required for age-related muscle fiber homeostasis, possibly independent of its role in protein synthesis.