Changes in MicroRNA expression patterns in human fibroblasts after low-LET radiation

Area of Science:

• Molecular Biology
• Radiation Biology
• Genomics

Background:

• Cellular responses to radiation are regulated by gene expression networks.
• MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression post-transcriptionally.
• Understanding miRNA dynamics after radiation is crucial for comprehending cellular radioresponse.

Purpose of the Study:

• To investigate changes in miRNA expression patterns in human fibroblasts after low (0.1 Gy) and high (2.0 Gy) doses of X-ray radiation.
• To correlate miRNA expression with mRNA and proteomic profiles.
• To elucidate the role of miRNAs in cellular responses to radiation, including DNA repair and apoptosis.

Main Methods:

• Exposure of human fibroblasts to varying doses of X-ray radiation (0.1 Gy and 2.0 Gy).
• Analysis of miRNA expression profiles at multiple time points (0.5 h, 2 h, 6 h, and 24 h) post-irradiation.
• Integration of miRNA data with mRNA and proteomic profiling.

Main Results:

• Irradiation induced both qualitative and quantitative differences in miRNA down-regulation, with specific miRNAs (e.g., miR-92b, 137) affected at early and late time points.
• A transient up-regulation of certain miRNAs (e.g., miR-558, 662) was observed 2 hours post-high-dose irradiation.
• Inverse correlation found between miRNA levels and their mRNA/protein targets after 2.0 Gy radiation.
• Specific miRNAs (miR-579, 608, 548-3p, 585) were identified as targeting genes involved in radioresponsive mechanisms like cell cycle checkpoint and apoptosis.

Conclusions:

• MicroRNAs act as key regulators in cellular responses to radiation, potentially mediating DNA repair and apoptosis.
• A proposed model suggests miRNAs are initially down-regulated to promote DNA repair, followed by up-regulation to suppress apoptosis for cell survival.
• MiRNAs may serve as valuable biodosimetric markers for assessing radiation exposure levels.