Biology Reference
In-Depth Information
VI. Conclusions
A. The human model
B. The road ahead
Acknowledgments
References
ABSTRACT
Since their initial discovery in maize, there have been various attempts to
categorize the relationship between transposable elements (TEs) and their host
organisms. These have ranged from TEs being selfish parasites to their role as
essential, functional components of organismal biology. Research over the past
several decades has, in many respects, only served to complicate the issue even
further. On the one hand, investigators have amassed substantial evidence
concerning the negative effects that TE-mutagenic activity can have on host
genomes and organismal fitness. On the other hand, we find an increasing
number of examples, across several taxa, of TEs being incorporated into func-
tional biological roles for their host organism. Some 45% of our own genomes are
comprised of TE copies. While many of these copies are dormant, having lost
their ability to mobilize, several lineages continue to actively proliferate in
modern human populations. With its complement of ancestral and active TEs,
the human genome exhibits key aspects of the host-TE dynamic that has played
out since early on in organismal evolution. In this review, we examine what
insights the particularly well-characterized human system can provide regarding
the nature of the host-TE interaction.
2011, Elsevier Inc.
I. INTRODUCTION
Transposable elements (TEs) are, at their essence, stretches of DNA that have
the capacity to mobilize themselves to different locations throughout a genome.
The wealth of new genomic sequencing data made available over the past decade
has allowed for significant advances in our understanding of the distribution and
diversity of these elements. In conjunction with important experimental work,
the analysis of sequencing data has served to highlight the importance of TE
mobilization and proliferation on organismal evolution. From the introduction of
alternative splice variants to the reshuffling of exons and entire genes, mobile
element activity has constituted a potent force shaping genome architecture
(Babushok
et al.
, 2007; Belancio
et al.
, 2008b; Lev-Maor
et al.
, 2003; Moran
et al.
,
1999; Sorek
et al.
, 2002; Xing
et al.
, 2006). TE activity is not relegated to the
