Transposable Elements, Polydactyl Proteins, and the Genesis of Human-Specific Transcription Networks

Cold Spring Harb Symp Quant Biol. 2015:80:281-8. doi: 10.1101/sqb.2015.80.027573. Epub 2016 Jan 13.

Abstract

Transposable elements (TEs) may account for up to two-thirds of the human genome, and as genomic threats they are subjected to epigenetic control mechanisms engaged from the earliest stages of embryonic development. We previously determined that an important component of this process is the sequence-specific recognition of TEs by KRAB (Krüppel-associated box)-containing zinc-finger proteins (KRAB-ZFPs), a large family of tetrapod-restricted transcription factors that act by recruiting inducers of heterochromatin formation and DNA methylation. We further showed that KRAB-ZFPs and their cofactor KAP1 exert a marked influence on the transcription dynamics of embryonic stem cells via their docking of repressor complexes at TE-contained regulatory sequences. It is generally held that, beyond this early embryonic period, TEs become permanently silenced, and that the evolutionary selection of KRAB-ZFPs and other TE controllers is the result of a simple evolutionary arms race between the host and these genetics invaders. Here, I discuss recent evidence that invalidates this dual assumption and instead suggests that KRAB-ZFPs are the instruments of a massive enterprise of TE domestication, whereby transposon-based regulatory sequences and their cellular ligands establish species-specific transcription regulation networks that influence multiple aspects of human development and physiology.

Publication types

  • Review
  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA Methylation / genetics*
  • DNA Transposable Elements / genetics*
  • Embryonic Stem Cells
  • Epigenesis, Genetic
  • Gene Expression Regulation, Developmental / genetics*
  • Gene Regulatory Networks / genetics*
  • Genome, Human
  • Heterochromatin / metabolism
  • Humans
  • Kruppel-Like Transcription Factors / metabolism
  • Transcription Factors / metabolism
  • Tripartite Motif-Containing Protein 28 / metabolism
  • Zinc Fingers

Substances

  • DNA Transposable Elements
  • Heterochromatin
  • Kruppel-Like Transcription Factors
  • Transcription Factors
  • TRIM28 protein, human
  • Tripartite Motif-Containing Protein 28