Genetic Analysis Of Methylation Pattern Of LINE1 And B1 In Mouse Bystander Organ Induced By Heavy-ion Irradiation

The research on biological mechanism of space radiation is becoming more and more important for human beings in space explorations. Many studies showed that space radiation could induce genetic changes as well as epigenetic patterns, in particular, the changes in DNA methylation status. Some researches found that two types of retro-transpositions, LINE1 (typical type of Long Interspersed Nuclear Elements) and B1 (typical type of Short Interspersed Nuclear Elements), spread widely among mammal genome. They play a key role in gene expression, and their methylation patterns have a close relationship with cancer and other diseases. What’s more, some researchers approved that their methylation patterns could represent the methylation patterns of the whole genome. Previous study in our lab had proved that radiating the head of a mouse with 12C6+ heavy-ion could obviously induced the changes of DNA methylation polymorphic rate in its liver. However, it was still unknown whether such kind of radiation could induce the changes of methylation of LINE1 and B1 in promoter of liver, whether these changes could be inherited in the filial generation.In the present work, 12C6+ heavy-ion (energy 1.98 GeV, dose rate 0.5GY/min, LET 30Kev/μm) with dose 200mGy was used to radiate the head of C57 male mouse. MSP method was used to analyze LINE1 and B1 methylation patterns of liver promoter after six months. The irradiated C57 male mated with the unirradiated C57 female (Fo) produced their next generation (F1). The descendants of F1 were denoted by F2. LINE1 and B1 methylation patterns of liver from F1 to F2 were also analyzed by MSP to judge whether radiation could cause the changes of methylation, whether there was a relationship between methylation and bystander effect as well as genome instability in three generations. By analyzing the methylation status of CG and the differences of SNP, it was found that only few changes in liver DNA methylation appeared. As a result, obvious inheritance was found. These results imply that 12C6+ heavy-ion could not change mice liver promoter of LINE1 or B1 methylation patterns, indicating that there are no relationship between the bystander effect, genome instability induced by heavy-ion radiation and the pattern of retro-transposition.