Only those genes of the KIAA1245 gene subfamily that contain HERV(K) LTRs in their introns are transcriptionally active

Insertion of LTRs into some genome locations might seriously affect regulation of the neighboring genes expression. This hypothesis is widely accepted but, however, not confirmed directly. Earlier, we have identified a family of closely related genes highly similar to the KIAA1245 mRNA counterpart. This family included a subfamily of genes some of which contained and the others lacked an LTR in their structure. We compared transcription of several closely related genes of the subfamily differing in the presence or absence of LTRs. Only LTR-containing genes were transcribed in transformed cell lines, tumorous and embryonic human tissues, whereas LTR-lacking genes remained silent. Since the genes were in the same intracellular microenvironment, we suggested that this effect was most probably due to intrinsic cis-characteristics of integrated LTRs and confirmed this by demonstrating high enhancer activity of KIAA1245 LTRs. The expression of the LTR-containing genes in embryonic tissues might suggest their involvement in evolutionary events during primate speciation.