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 its host. The sheer magnitude of L1 sequences in our genome has fueled speculation that over evolutionary time L1 insertions may structurally modify endogenous genes and regulate gene expression. Here we provide a review of L1 replication and its potential functional consequences.
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http://dx.doi.org/10.1002/bies.20257 | DOI Listing |
Genes Dev
January 2025
Institute for Research on Cancer and Aging of Nice (IRCAN), Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS), University Cote d'Azur, Nice 06107, France
Long interspersed element-1 (LINE-1) retrotransposons are abundant transposable elements in mammals and significantly influence chromosome structure, chromatin organization, and 3D genome architecture. In this issue of , Ataei et al. (doi:10.
View Article and Find Full Text PDFEMBO Rep
January 2025
Myeloid Therapeutics Inc., Cambridge, MA, 02139, USA.
To address a wide range of genetic diseases, genome editing tools that can achieve targeted delivery of large genes without causing double-strand breaks (DSBs) or requiring DNA templates are necessary. Here, we introduce CRISPR-Enabled Autonomous Transposable Element (CREATE), a genome editing system that combines the programmability and precision of CRISPR/Cas9 with the RNA-mediated gene insertion capabilities of the human LINE-1 (L1) element. CREATE employs a modified L1 mRNA to carry a payload gene, and a Cas9 nickase to facilitate targeted editing by L1-mediated reverse transcription and integration without relying on DSBs or DNA templates.
View Article and Find Full Text PDFPLoS One
January 2025
Faculty of Biology, VNU University of Science, Vietnam National University, Hanoi, Vietnam.
The autonomous and active Long-Interspersed Element-1 (LINE-1, L1) and the non-autonomous Alu retrotransposon elements, contributing to 30% of the human genome, are the most abundant repeated sequences. With more than 90% of their sequences being methylated in normal cells, these elements undeniably contribute to the global DNA methylation level and constitute a major part of circulating-cell-free DNA (cfDNA). So far, the hypomethylation status of LINE-1 and Alu in cellular and extracellular DNA has long been considered a prevailing hallmark of ageing-related diseases and cancer.
View Article and Find Full Text PDFbioRxiv
December 2024
Department of Data Science, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
LINE-1 (L1) retrotransposition is widespread in many cancers, especially those with a high burden of chromosomal rearrangements. However, whether and to what degree L1 activity directly impacts genome integrity is unclear. Here, we apply whole-genome sequencing to experimental models of L1 expression to comprehensively define the spectrum of genomic changes caused by L1.
View Article and Find Full Text PDFbioRxiv
December 2024
Sanford I. Weill Department of Medicine, Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, NY 10065, USA.
Mouse embryonic stem cells (mESCs) and other naïve pluripotent stem cells can reverse typical developmental trajectories and, at low frequency, de-differentiate into 2-cell-like cells (2CLCs) that resemble the mammalian embryo during zygotic genome activation (ZGA). This affords the opportunity to reveal molecular principles that govern the pre-implantation stages of mammalian development. We leveraged a multipurpose allele for acute protein depletion and efficient immunoprecipitation to dissect the molecular functions of the chromatin repressor EHMT2, a candidate antagonist of the mESC-to-2CLC transition.
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