New insight into transcription of human endogenous retroviral elements.

It is generally assumed that human endogenous retroviral elements (HERVs) belong to the class of genomic repetitive nucleotide sequences often called 'junk DNA'. These elements were categorized to families, and members of some of these families (e.g. HERV-H, HERV-W and HERV-K) were shown to be transcribed. These transcriptions were associated with several severe diseases such as mental disorders, AIDS, autoimmune diseases and cancer. In this review we discuss several bioinformatics strategies for genome-wide scan of HERVs transcription using high-throughput RNA sequencing on several platforms. We show that many more HERVs than previously described are transcribed to various levels and we discuss possible implications of these transcriptions.