Primate specific retrotransposons, SVAs, in the evolution of networks that alter brain function

Abstract

The hominid-specific non-LTR retrotransposon termed SINE VNTR Alu (SVA) is the youngest of the transposable elements in the human genome. The propagation of the most ancient SVA type A took place about thirteen millions years ago ago, and the youngest SVA types appeared in the human genome after the chimpanzee divergence. Functional enrichment analysis of genes associated with SVA insertions demonstrated their strong link to multiple ontological categories attributed to brain function and the disorders. SVA types that expanded their presence in the human genome at different stages of hominoid life history were also associated with progressively evolving behavioural features that indicated a potential impact of SVA propagation on a cognitive ability of a modern human. The SVA-associated genes were highly cross-linked in functional networks suggesting an accumulative impact of functional alterations potentially caused by SVA insertions. Our analysis uncovered a potential role of SVAs in evolution of human CNS and especially emergence of functional trends relevant to social and parental behaviour. It also supports models which explain in part how brain function can be modulated by both the immune and reproductive systems based on the gene expression patterns and gene pathways potentially altered by SVA insertions.