LINE‐1 retrotransposons: Modulators of quantity and quality of mammalian gene expression?

  title={LINE‐1 retrotransposons: Modulators of quantity and quality of mammalian gene expression?},
  author={Jeffrey S. Han and Jef D. Boeke},
LINE‐1 (L1) retrotransposons are replicating repetitive elements that, by mass, are the most‐abundant sequences in the human genome. Over one‐third of mammalian genomes are the result, directly or indirectly, of L1 retrotransposition. L1 encodes two proteins: ORF1, an RNA‐binding protein, and ORF2, an endonuclease/reverse transcriptase. Both proteins are required for L1 mobilization. Apart from the obvious function of self‐replication, it is not clear what other roles, if any, L1 plays within… 
LINE-1 Retrotransposition: Impact on Genome Stability and Diversity and Human Disease
When we started thinking about devoting an issue of the Journal of Biomedicine and Biotechnology to LINE-1s, we were not sure it would fly. LINE-1s are long interspersed elements that account for 17%
L1 elements, processed pseudogenes and retrogenes in mammalian genomes
There is a significant excess ofretrogenes that originate from the X chromosome and are retrotransposed into autosomes, and most of these retrogenes are specially expressed in male germ cells, suggesting the inactivation of X‐linked genes during male meiosis provides a strong selection pressure on retrogenses originating from theX chromosome.
The ORF1 Protein Encoded by LINE-1: Structure and Function During L1 Retrotransposition
Significant advances have been made such that it is known that ORF1p is a high affinity RNA binding protein that forms a ribonucleoprotein particle together with L1 RNA and this nucleic acid chaperone activity is required for L1 retrotransposition.
The Intersection of Genetics and Epigenetics: Reactivation of Mammalian LINE-1 Retrotransposons by Environmental Injury
Because L1 insertions can have a profound impact on primary genetic structure as well as epigenetic status of the host, they represent ideal molecular targets for development of novel epigenetic therapies targeting medical conditions that involve derangements of L1 activity.
Turning junk into gold: domestication of transposable elements and the creation of new genes in eukaryotes
  • J. Volff
  • Biology
    BioEssays : news and reviews in molecular, cellular and developmental biology
  • 2006
There is indeed substantial evidence that mobile DNA can serve as a dynamic reservoir for new cellular functions and new aspects of evolutionary alchemy, the turning of junk into gold within genomes are uncovered.
Insights into the DNA cleavage mechanism of human LINE‐1 retrotransposon endonuclease
Molecular dynamics simulations using as model the structures of wild type EN‐L1, of two βB6‐βB5 loop exchange mutants the authors have described previously to be important for DNA recognition, of the R155A mutant from this study, and of the homologous TRAS1 endonuclease confirm a rigid scaffold.
hnRNPL and nucleolin bind LINE-1 RNA and function as host factors to modulate retrotransposition
Findings are consistent with NCL acting as an IRES trans-acting factor (ITAF) for ORF2 translation and hence a positive host factor for L1 retrotransposition, and hnRNPL joins a small, but growing list of cellular proteins that are potent negative regulators of L1 Retrotransposition.
LINEs between Species: Evolutionary Dynamics of LINE-1 Retrotransposons across the Eukaryotic Tree of Life
The remarkable and overlooked diversity of L1s is demonstrated via a comprehensive phylogenetic analysis of over 500 species from widely divergent branches of the tree of life, illustrating how both long-term inherited evolutionary patterns and random bursts of activity in individual species can significantly alter genomes.


Transcriptional disruption by the L1 retrotransposon and implications for mammalian transcriptomes
It is shown that inserting L1 sequences on a transcript significantly decreases RNA expression and therefore protein expression, andBioinformatic data are consistent with the hypothesis that L1 can serve as an evolutionary fine-tuner of the human transcriptome.
Members of the SRY family regulate the human LINE retrotransposons.
It is shown that factors belonging to the family of the testis-determining factor gene SRY (the SOX family) can modulate L1H promoter activity over a 10-fold range in a transient transfection assay using a luciferase reporter gene.
Human L1 Retrotransposition: cisPreference versus trans Complementation
It is concluded that L1-encoded proteins demonstrate a profoundcis preference for their encoding RNA, which could enable L1 to remain retrotransposition competent in the presence of the overwhelming number of nonfunctional L1s present in human DNA.
Nucleic Acid Chaperone Activity of the ORF1 Protein from the Mouse LINE-1 Retrotransposon
A role for L1 ORF1p is suggested in mediating nucleic acid strand transfer steps during L1 reverse transcription, promoting annealing of complementary DNA strands, and facilitating strand exchange to form the most stable hybrids in competitive displacement assays.
Human L1 element target‐primed reverse transcription in vitro
The initial stages of L1 element transposition in vitro is reconstituted and evidence for specific positioning of the L1 RNA with the ORF2 protein is found, probably mediated in part by the polyadenosine portion of L 1 RNA.
Mammalian LINE-1 Retrotransposons and Related Elements
This chapter emphasises on the studies that have focused on understanding the mechanism of L1 retrotransposition, which were conducted since the publication of Mobile DNA in 1989 and biochemical data argue that ORF1 binds particular A-rich sequences in L1 RNA with relatively high affinity and that OrF1p is more abundant than ORF2p.
Antisense Promoter of Human L1 Retrotransposon Drives Transcription of Adjacent Cellular Genes
  • M. Speek
  • Biology
    Molecular and Cellular Biology
  • 2001
It is shown that a hitherto unknown L1Hs antisense promoter (ASP) drives the transcription of adjacent genes, and this type of transcriptional control may be widespread.
LINE-mediated retrotransposition of marked Alu sequences
It is shown that the poly-A stretch at the Alu 3′ end is essential for mobility, that LINEs are required for transposition and that the rate of retroposition is 100–1,000 times higher for Alu transcripts than for control mRNAs, thus accounting for the high mutational activity of these elements observed in humans.