Mobile DNA elements are discrete DNA sequences that have the remarkable ability to transport or duplicate themselves to other regions of the host genome. Because of the ubiquity of this process, mobile elements account for at least 40-50% of the content of mammalian genomes, including human.
Approximately 45% of the human genome can currently be recognized as being derived from transposable elements.
In human genomes, retrotransposons, especially Alus and L1s, have played significant role in shaping human genomic diversity and evolution. These repeat elements tend to promote unequal crossover and are an important factor contributing to genomic instability. Mobile element insertions can also cause disease either directly by interrupting a gene, or by mediate nonhomologous recombination, resulting in disease-causing insertions and deletions. In addition to their genomic impact, mobile elements are highly useful as genetic markers in tracing relationships of populations and species.
Despite the profound impact of mobile elements on the human genomic diversity, the repetitive nature of the mobile elements makes them particularly difficult to study at the whole genome level. We have recently developed a high-throughput, low-cost method (ME-Scan) to genotype mobile DNA element insertions using next-generation sequencing technology. We are currently applying this method to human samples from world-wide populations. Using the data generated, We will be able to answer questions related to several aspects of mobile element biology, and assess their impact on the human genomic diversity.
ME-Scan library construction procedure. (a) DNA fragmentation; (b) end repair; (c) A-tailing; (d) adaptor ligation; (e) first PCR amplification; (f) beads capture; (g) second PCR amplification; (h) library validation; (i) high-throughput sequencing