The role of chimeric LINE-1 transcripts in the human placenta during the first trimester of pregnancy

Abstract

LINE-1 retrotransposon is widely represented in the human genome and can function as an alternative promoter in genes. The activity of LINE-1 is regulated by DNA methylation. Previously, we showed that LINE-1 is hypomethylated in normal placenta and hypermethylated in chorionic villi of spontaneous abortions. Abnormalities in the methylation of mobile elements may affect the expression of chimeric LINE-1 transcripts. In this study, for the first time, we identified genes expressed from the alternative LINE-1 promoter in the human placenta during the first trimester of pregnancy. Chimeric transcripts of these genes are involved in placental development processes, and a deficiency in their expression could potentially lead to placental dysfunction and embryolethality.