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Sang Rok Lee

Bio: Sang Rok Lee is an academic researcher from Chosun University. The author has contributed to research in topics: Peptide sequence & Cloning vector. The author has an hindex of 1, co-authored 1 publications receiving 1042 citations.

Papers
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Journal ArticleDOI
29 Apr 2011-PLOS ONE
TL;DR: Western blotting and confocal microscopic analyses revealed that among the four 2As, the one derived from porcine teschovirus-1 (P2A) has the highest cleavage efficiency in all the contexts examined.
Abstract: When expression of more than one gene is required in cells, bicistronic or multicistronic expression vectors have been used. Among various strategies employed to construct bicistronic or multicistronic vectors, an internal ribosomal entry site (IRES) has been widely used. Due to the large size and difference in expression levels between genes before and after IRES, however, a new strategy was required to replace IRES. A self-cleaving 2A peptide could be a good candidate to replace IRES because of its small size and high cleavage efficiency between genes upstream and downstream of the 2A peptide. Despite the advantages of the 2A peptides, its use is not widespread because (i) there are no publicly available cloning vectors harboring a 2A peptide gene and (ii) comprehensive comparison of cleavage efficiency among various 2A peptides reported to date has not been performed in different contexts. Here, we generated four expression plasmids each harboring different 2A peptides derived from the foot-and-mouth disease virus, equine rhinitis A virus, Thosea asigna virus and porcine teschovirus-1, respectively, and evaluated their cleavage efficiency in three commonly used human cell lines, zebrafish embryos and adult mice. Western blotting and confocal microscopic analyses revealed that among the four 2As, the one derived from porcine teschovirus-1 (P2A) has the highest cleavage efficiency in all the contexts examined. We anticipate that the 2A-harboring cloning vectors we generated and the highest efficiency of the P2A peptide we demonstrated would help biomedical researchers easily adopt the 2A technology when bicistronic or multicistronic expression is required.

1,249 citations


Cited by
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Journal ArticleDOI
TL;DR: The engineering of mScarlet is reported, a truly monomeric red fluorescent protein with record brightness, quantum yield, and fluorescence lifetime and it is especially useful as a Förster resonance energy transfer (FRET) acceptor in ratiometric imaging.
Abstract: We report the engineering of mScarlet, a truly monomeric red fluorescent protein with record brightness, quantum yield (70%) and fluorescence lifetime (3.9 ns). We developed mScarlet starting with a consensus synthetic template and using improved spectroscopic screening techniques; mScarlet's crystal structure reveals a planar and rigidified chromophore. mScarlet outperforms existing red fluorescent proteins as a fusion tag, and it is especially useful as a Forster resonance energy transfer (FRET) acceptor in ratiometric imaging.

784 citations

Journal ArticleDOI
22 May 2014-Nature
TL;DR: The development of a focused CRISPR/Cas-based (clustered regularly interspaced short palindromic repeats/CRISPR-associated) lentiviral library in human cells and a method of gene identification based on functional screening and high-throughput sequencing analysis are reported.
Abstract: Targeted genome editing technologies are powerful tools for studying biology and disease, and have a broad range of research applications. In contrast to the rapid development of toolkits to manipulate individual genes, large-scale screening methods based on the complete loss of gene expression are only now beginning to be developed. Here we report the development of a focused CRISPR/Cas-based (clustered regularly interspaced short palindromic repeats/CRISPR-associated) lentiviral library in human cells and a method of gene identification based on functional screening and high-throughput sequencing analysis. Using knockout library screens, we successfully identified the host genes essential for the intoxication of cells by anthrax and diphtheria toxins, which were confirmed by functional validation. The broad application of this powerful genetic screening strategy will not only facilitate the rapid identification of genes important for bacterial toxicity but will also enable the discovery of genes that participate in other biological processes.

695 citations

Journal ArticleDOI
21 Nov 2013-Cell
TL;DR: ATR-mediated suppression of dormant origins shields active forks against irreversible breakage via preventing exhaustion of nuclear RPA, elucidates how replicating genomes avoid destabilizing DNA damage and provides a molecular rationale for their hypersensitivity to ATR inhibitors.

651 citations

Journal ArticleDOI
TL;DR: It is shown that expression levels are a bottleneck in base-editing efficiency, and cytidine and adenine base editors are optimized by modification of nuclear localization signals and codon usage, and ancestral reconstruction of the deaminase component.
Abstract: Base editors enable targeted single-nucleotide conversions in genomic DNA. Here we show that expression levels are a bottleneck in base-editing efficiency. We optimize cytidine (BE4) and adenine (ABE7.10) base editors by modification of nuclear localization signals (NLS) and codon usage, and ancestral reconstruction of the deaminase component. The resulting BE4max, AncBE4max, and ABEmax editors correct pathogenic SNPs with substantially increased efficiency in a variety of mammalian cell types.

572 citations

Journal ArticleDOI
TL;DR: It is concluded that human airway organoids represent versatile models for the in vitro study of hereditary, malignant, and infectious pulmonary disease.
Abstract: Organoids are self-organizing 3D structures grown from stem cells that recapitulate essential aspects of organ structure and function. Here, we describe a method to establish long-term-expanding human airway organoids from broncho-alveolar resections or lavage material. The pseudostratified airway organoids consist of basal cells, functional multi-ciliated cells, mucus-producing secretory cells, and CC10-secreting club cells. Airway organoids derived from cystic fibrosis (CF) patients allow assessment of CFTR function in an organoid swelling assay. Organoids established from lung cancer resections and metastasis biopsies retain tumor histopathology as well as cancer gene mutations and are amenable to drug screening. Respiratory syncytial virus (RSV) infection recapitulates central disease features, dramatically increases organoid cell motility via the non-structural viral NS2 protein, and preferentially recruits neutrophils upon co-culturing. We conclude that human airway organoids represent versatile models for the in vitro study of hereditary, malignant, and infectious pulmonary disease.

569 citations