Low-Dose Ionizing Radiation Modulates Translation Efficiency in Human Lung Fibroblasts

Understanding the cellular responses to low-dose ionizing radiation exposure (≤ 0.1 Gy) is essential for developing evidence-based radiation protection policies. Unlike high-dose radiation exposure, which is known to alter gene expression and protein synthesis, the cellular impact of low-dose exposure remains less defined. To address this gap, ribosome profiling was performed on normal human lung fibroblast cells exposed to low (0.1 Gy) and high (1 Gy) doses of 60Cobalt gamma (γ) rays. At 1 and 6 h postirradiation, global protein synthesis remained unchanged at low dose; however, specific mRNAs showed altered translation efficiency. These translational shifts occurred despite minimal changes at the transcriptional level, indicating that translation offers a more sensitive readout of early low-dose γ-radiation effects. The small GTP-binding protein RAB33B was identified as a translationally upregulated target. This study emphasizes that conventional transcriptome analyses do not fully capture gene expression dynamics and suggests that selective translation could contribute to a distinct cellular response to low-dose irradiation.