Publications by authors named "Xiang-Ru Shannon Xu"

2 Publications

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Active Genetic Neutralizing Elements for Halting or Deleting Gene Drives.

Mol Cell 2020 10 18;80(2):246-262.e4. Epub 2020 Sep 18.

Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA; Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA, USA. Electronic address:

CRISPR-Cas9-based gene drive systems possess the inherent capacity to spread progressively throughout target populations. Here we describe two self-copying (or active) guide RNA-only genetic elements, called e-CHACRs and ERACRs. These elements use Cas9 produced in trans by a gene drive either to inactivate the cas9 transgene (e-CHACRs) or to delete and replace the gene drive (ERACRs). e-CHACRs can be inserted at various genomic locations and carry two or more gRNAs, the first copying the e-CHACR and the second mutating and inactivating the cas9 transgene. Alternatively, ERACRs are inserted at the same genomic location as a gene drive, carrying two gRNAs that cut on either side of the gene drive to excise it. e-CHACRs efficiently inactivate Cas9 and can drive to completion in cage experiments. Similarly, ERACRs, particularly those carrying a recoded cDNA-restoring endogenous gene activity, can drive reliably to fully replace a gene drive. We compare the strengths of these two systems.
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http://dx.doi.org/10.1016/j.molcel.2020.09.003DOI Listing
October 2020

CRISPR/Cas9 and active genetics-based trans-species replacement of the endogenous -L2 CRM reveals unexpected complexity.

Elife 2017 12 23;6. Epub 2017 Dec 23.

Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California.

The () locus encodes transcription factors required for induction of the L2 wing vein in . Here, we employ diverse CRISPR/Cas9 genome editing tools to generate a series of targeted lesions within the endogenous cis-regulatory module (CRM) required for expression in the L2 vein primordium. Phenotypic analysis of these '' mutations based on both expression of Kni protein and adult wing phenotypes, reveals novel unexpected features of L2-CRM function including evidence for a chromosome pairing-dependent process that promotes transcription. We also demonstrate that self-propagating active genetic elements (CopyCat elements) can efficiently delete and replace the L2-CRM with orthologous sequences from other divergent fly species. Wing vein phenotypes resulting from these trans-species enhancer replacements parallel features of the respective donor fly species. This highly sensitive phenotypic readout of enhancer function in a native genomic context reveals novel features of CRM function undetected by traditional reporter gene analysis.
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http://dx.doi.org/10.7554/eLife.30281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5800851PMC
December 2017