Here, we devise a novel approach to systematically dissect the genome-wide consequences of TE insertion on gene expression, and test the hypothesis that classes of endogenous retrovirus long terminal repeats (LTRs) exert tissue-specific regulation of adjacent genes.
The generation of cell clones also provided the opportunity to explore the effects of transposon insertion on gene expression, which is the key to our functional mutagenesis approach As illustrated by our analysis of ABCB1 in the next section, 'sense' insertions upstream of genes consistently resulted in increased expression as expected.
The work presented will allow the development of new molecular markers for grapevine selection and breeding, and the examples of MITE polymorphic insertions within genes reported here will allow in the future to experimentally test the direct impact of MITE insertions on gene expression.
In general we believe that our results are a conservative estimate of the effects of transposable element insertions on gene expression.
To estimate the effect size of private TE insertions on gene expression levels, we carried out a parametric analysis.
A small number of "metastable epialleles" have been identified in mice (e.g. Avy, CabpIAP, and AxinFu) in which variable methylation of the 5′ LTR of an antisense IAP insertion results in dysregulation of gene expression concomitant with the level of methylation [ 16- 20].
Instead, it appears that the T-DNA insertion in RLK902 leads to downregulation of gene expression within a flanking 84 kb genomic region.
On the contrary, this study provides an example of an insertion that resulted in the liberation of gene expression.
In higher plants, in addition to their large genome sizes, mtDNAs display distinctive features, including slow evolutionary rate, rapid rearrangement, frequent insertion, complex multipartite structure, specific mode of gene expression, cis-/ trans-splicing, RNA editing, and use of the universal genetic code [ 5].
As in other higher plants, all three sequenced mitochondrial genomes had large sizes and distinctive features, including slow evolutionary rates, rapid rearrangement, frequent insertion, complex multipartite structures, specific modes of gene expression, cis- and trans-splicing, RNA editing and the use of universal genetic code [ 21].
