Objective: Epigenetic regulations of insulin-like growth factor 2 (IGF2) were observed during cellular replicative senescence and premature senescence induced by hydrogen peroxide of human embryonic lung fibroblasts (HEFs).
Methods: The mRNA level of IGF2 was detected by Q-PCR. The methylation status in the promoter region was observed by methylation-specific PCR. The histone modifications was detected by chromatin immunoprecipitation-Q-PCR assay, including acetylation for H3, H4 and methylation for H3 ( Lys4) and H4 (Lys20).
Results: In the process of cellular senescence, the mRNA level of IGF2 increased in both mid-aged and replicative senescent cells, but increased obviously in premature senescent cells compared with that of young cells. In the promotor region from -658 bp to -456 bp, the methylation level for IGF2 was detected only in replicative senescent cells. About the main histone modifications, IGF2 in the region (-856 bp - -634 bp) was H4 acetylation and H3K4 methylation in replicative senescence, while in the region (+9 bp - +145 bp) was H3K4 and H4K20 methylation in replicative senescence and H3K4 methylation in premature senescence.
Conclusion: The histone modifications take part in regulating the mRNA expression for IGF2 during cellular senescence and different mechanisms exist between two types of senescence.