Chromosomal tethering and proviral integration.

Since integration into the host cell genome is an obligatory step for their replication, retro-elements are both potent insertional mutagens and also suitable vectors for gene therapy. Many recent studies reported that the integration process is not random but, on the contrary, higly regulated at the molecular level. Many viral proteins and cellular factors play a key role in the integration step, explaining the reason why different retro-elements display distinct integration profiles. This review describes the recent highlights about integration of retro-elements with particular focus on the mechanisms underlying the specificity of integration target-site selection and the step of chromosomal tethering which preceeds insertion of the provirus.