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Gene-breaking: a new paradigm for human retrotransposon-mediated gene evolution
Sarah J Wheelan1, Yasunori Aizawa, Jeffrey S Han
1Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Genome Research
|July 19, 2005
Summary
The L1 retrotransposon can break mammalian genes by inserting into them. This process, identified through bioinformatic analysis and experiments, creates novel transcripts and reshapes genomes.
Area of Science:
- Genomics
- Molecular Biology
- Evolutionary Biology
Background:
- L1 retrotransposons are highly successful autonomous elements in mammalian genomes.
- These elements can influence host gene expression and cause genome rearrangements.
- The potential for L1 elements to disrupt gene structure was previously unexplored.
Purpose of the Study:
- To investigate whether full-length L1 retrotransposons inserted in antisense orientation can split cellular genes.
- To identify instances of L1-mediated gene-breaking in the human genome.
- To explore the functional consequences of L1-induced gene splitting.
Main Methods:
- Bioinformatic analysis to identify genes potentially disrupted by L1 elements.
- Experimental validation of the L1 gene-breaking hypothesis.
- Analysis of L1 insertion timing relative to human/chimp divergence.
Main Results:
- Evidence supporting the L1 gene-breaking hypothesis was found.
- Three human genes were identified as apparently "broken" by L1 elements, with 12 additional candidates.
- Most identified L1 elements predate the human/chimp divergence.
- Split transcripts may encode interacting or novel proteins.
Conclusions:
- L1 retrotransposons can "break" host genes, generating distinct transcripts.
- This gene-breaking mechanism represents a novel way L1 elements remodel mammalian genomes.
- The identified gene-breaking events have evolutionary implications, potentially creating new protein functions.