Low doses of neutrons induce changes in gene expression

Area of Science:

• Molecular Biology
• Radiation Biology
• Virology

Background:

• Previous studies identified genes modulated by both neutron and gamma radiation, but differences in beta-protein kinase C and c-fos gene expression were noted.
• Gamma rays induced beta-protein kinase C and c-fos, while neutrons did not.

Purpose of the Study:

• To identify genes specifically induced by low-dose neutron radiation, but not by gamma rays.
• To investigate the differential gene expression patterns in response to distinct radiation types.

Main Methods:

• Utilized Syrian hamster embryo (SHE) fibroblasts to assess Rp-8 mRNA induction after neutron exposure at varying dose rates.
• Employed HeLa cells with a transfected chloramphenicol acetyl transferase (CAT) gene construct driven by the human immunodeficiency virus (HIV) long terminal repeat (LTR) promoter to measure LTR induction.
• Assessed CAT activity and transcripts following irradiation with neutrons and gamma rays, and evaluated ultraviolet-mediated HIV-LTR induction after neutron exposure.

Main Results:

• Rp-8 mRNA was induced in SHE fibroblasts by neutrons at both low and high dose rates; other apoptosis-related genes (Rp-2, bcl-2, Tcl-30) were not induced.
• HIV-LTR transcription was induced by low-dose-rate neutrons (0.05 Gy/min) but not high-dose-rate neutrons (0.12 Gy/min) or gamma rays (0.1-3 Gy).
• Low-dose-rate neutron irradiation inhibited ultraviolet-mediated HIV-LTR induction.

Conclusions:

• Neutron radiation, particularly at low dose rates, selectively induces Rp-8 and HIV-LTR, suggesting distinct cellular responses compared to gamma radiation.
• The findings correlate Rp-8 induction with apoptosis and HIV's known association with apoptosis, warranting further investigation into these relationships.
• Differential induction of specific genes by neutron versus gamma radiation highlights the importance of radiation quality in cellular responses.