Transposable elements make up half of our DNA. They control gene expression and have been a major evolutionary force in all organisms. The Schorn lab investigates how small RNAs identify and silence transposable elements when they become active during development and cancer.
‘Mobile genes’ or transposable elements, which are closely related to viruses, promote active gene expression in a selfish manner. These elements are usually buried in inactive, condensed DNA by their host to prevent mutagenic damage. However, both stem cells in the embryo and cancer cells undergo genome-wide reprogramming that re-activates silent transposable elements. My lab is exploring how the host recognizes transposons amongst thousands of genes and non-coding DNA and specifically restricts transposon mobility.
We found that a highly conserved 18 nucleotide sequence motif is the Achille’s heel of a wide-spread class of transposable elements that are closely related to retroviruses such as HIV. These retroelements initiate replication at the 18 nucleotide binding site using transfer RNA (tRNA), an essential RNA component of the cell. In turn, cells produce short fragments of tRNAs that we discovered inhibit this class of retroelements. These tRNA fragments are processed from mature tRNAs under yet unknown conditions and potentially protect many cell types in eukaryotes. We are investigating under which conditions cells produce this class of small RNAs and assessing their impact on development and pluripotency. tRNA fragments are an ancient link between the ‘RNA interference’ silencing machinery, transposons and genome stability, with potential roles in trans-generational inheritance and cancer.
Andrea Schorn zooms in on small RNAs in the cell
April 29, 2019
Dr. Andrea Schorn joins CSHL faculty as research assistant professor. Her focus is exploring transposable elements in the genome of mammalian cells.
Newly identified small RNA fragments defend the genome when it’s ‘naked’
June 29, 2017
Fragments snipped from tRNAs protect embryonic stem cells while they’re being epigenetically reprogrammed.
He, C. and Bozler, J. and Janssen, K. A. and Wilusz, J. E. and Garcia, B. A. and Schorn, A. J. and Bonasio, R. (2021) TET2 chemically modifies tRNAs and regulates tRNA fragment levels. Nature Structural and Molecular Biology, 28(1) pp. 62-70.
Cullen, H. and Schorn, A. J. (2020) Endogenous Retroviruses Walk a Fine Line between Priming and Silencing. Viruses, 12(8) pp. 792-792.
Lee, S.C. and Ernst, E. and Berube, B. and Borges, F. and Parent, J. S. and Ledon, P. and Schorn, A. and Martienssen, R. A. (2020) Arabidopsis Retrotransposon Virus-Like Particles and Their Regulation by Epigenetically Activated Small RNA. Genome Research, 30(4) pp. 576-588.
Schorn, A. J. and Martienssen, R. (2019) Getting in LINE with Replication. Molecular Cell, 74(3) pp. 415-417.
Schorn, A. J. and Martienssen, R. A. (2018) Tie-Break: Host and Retrotransposons Play tRNA. Trends in Cell Biology, 28(10) pp. 793-806.
Schorn, A. J. and Gutbrod, M. J. and LeBlanc, C. and Martienssen, R. (2017) LTR-Retrotransposon Control by tRNA-Derived Small RNAs. Cell, 170(1) pp. 61-71.Additional materials of the author at
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