Mechanical loading induces the longitudinal growth of muscle fibers via a rapamycin-insensitive mechanism

Mechanical loading drives skeletal muscle growth, yet the mechanisms that regulate this process remain undefined. The data in this study show that an increase in mechanical loading induces muscle fiber growth through two distinct mechanisms. Radial growth, reflected by an increase in fiber cross-sectional area, is mediated through a rapamycin-sensitive signaling pathway, whereas longitudinal growth, marked by the in-series addition of sarcomeres, is mediated through a rapamycin-insensitive signaling pathway. To gain further insight into the events that drive longitudinal growth, we combined BONCAT-based labeling of newly synthesized proteins with high-resolution imaging and determined that the in-series addition of sarcomeres is mediated by a process that involves transverse splitting at the Z-lines of pre-existing sarcomeres. Collectively, our findings not only challenge the long-standing view that mechanically induced growth is uniformly governed by mTORC1, but they also lay the frame..., , # Mechanical loading induces the longitudinal growth of muscle fibers via a rapamycin-insensitive mechanism

Dataset DOI: [10.5061/dryad.z612jm6r8](https://doi.org/10.5061/dryad.z612jm6r8)

## Description of the data and file structure

The details about all of the experiments that led to data in this file are provided in the main manuscript

### Files and variables

All sheets within the file Source_Data.xlsx are also provided as a .CSV file.

#### File: Source_Data.xlsx

**Description:** The file is presented in a Microsoft Excel format. Where applicable, the formulas for converting raw values into relative values have been included so that readers can determine how the values were derived for each experiment. In some cases, the file also contains highlighted cells so that readers can identify which samples came from which animals.

**Figure 1:** C57BL/6J mice were subjected to a mechanical overload (MOV) or sham (control) surgery and injected daily with either rapamycin (RAP) or the...,