1
|
Chan SH, Molé CN, Nye D, Mitchell L, Dai N, Buss J, Kneller DW, Whipple JM, Robb GB. Biochemical characterization of mRNA capping enzyme from Faustovirus. RNA 2023; 29:1803-1817. [PMID: 37625853 PMCID: PMC10578482 DOI: 10.1261/rna.079738.123] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 08/07/2023] [Indexed: 08/27/2023]
Abstract
The mammalian mRNA 5' cap structures play important roles in cellular processes such as nuclear export, efficient translation, and evading cellular innate immune surveillance and regulating 5'-mediated mRNA turnover. Hence, installation of the proper 5' cap is crucial in therapeutic applications of synthetic mRNA. The core 5' cap structure, Cap-0, is generated by three sequential enzymatic activities: RNA 5' triphosphatase, RNA guanylyltransferase, and cap N7-guanine methyltransferase. Vaccinia virus RNA capping enzyme (VCE) is a heterodimeric enzyme that has been widely used in synthetic mRNA research and manufacturing. The large subunit of VCE D1R exhibits a modular structure where each of the three structural domains possesses one of the three enzyme activities, whereas the small subunit D12L is required to activate the N7-guanine methyltransferase activity. Here, we report the characterization of a single-subunit RNA capping enzyme from an amoeba giant virus. Faustovirus RNA capping enzyme (FCE) exhibits a modular array of catalytic domains in common with VCE and is highly efficient in generating the Cap-0 structure without an activation subunit. Phylogenetic analysis suggests that FCE and VCE are descended from a common ancestral capping enzyme. We found that compared to VCE, FCE exhibits higher specific activity, higher activity toward RNA containing secondary structures and a free 5' end, and a broader temperature range, properties favorable for synthetic mRNA manufacturing workflows.
Collapse
Affiliation(s)
- S Hong Chan
- New England Biolabs, Inc., Ipswich, Massachusetts 01938, USA
| | - Christa N Molé
- New England Biolabs, Inc., Ipswich, Massachusetts 01938, USA
| | - Dillon Nye
- New England Biolabs, Inc., Ipswich, Massachusetts 01938, USA
| | - Lili Mitchell
- New England Biolabs, Inc., Ipswich, Massachusetts 01938, USA
| | - Nan Dai
- New England Biolabs, Inc., Ipswich, Massachusetts 01938, USA
| | - Jackson Buss
- New England Biolabs, Inc., Ipswich, Massachusetts 01938, USA
| | | | | | - G Brett Robb
- New England Biolabs, Inc., Ipswich, Massachusetts 01938, USA
| |
Collapse
|
2
|
Christie KA, Guo JA, Silverstein RA, Doll RM, Mabuchi M, Stutzman HE, Lin J, Ma L, Walton RT, Pinello L, Robb GB, Kleinstiver BP. Precise DNA cleavage using CRISPR-SpRYgests. Nat Biotechnol 2023; 41:409-416. [PMID: 36203014 PMCID: PMC10023266 DOI: 10.1038/s41587-022-01492-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 08/31/2022] [Indexed: 11/09/2022]
Abstract
Methods for in vitro DNA cleavage and molecular cloning remain unable to precisely cleave DNA directly adjacent to bases of interest. Restriction enzymes (REs) must bind specific motifs, whereas wild-type CRISPR-Cas9 or CRISPR-Cas12 nucleases require protospacer adjacent motifs (PAMs). Here we explore the utility of our previously reported near-PAMless SpCas9 variant, named SpRY, to serve as a universal DNA cleavage tool for various cloning applications. By performing SpRY DNA digests (SpRYgests) using more than 130 guide RNAs (gRNAs) sampling a wide diversity of PAMs, we discovered that SpRY is PAMless in vitro and can cleave DNA at practically any sequence, including sites refractory to cleavage with wild-type SpCas9. We illustrate the versatility and effectiveness of SpRYgests to improve the precision of several cloning workflows, including those not possible with REs or canonical CRISPR nucleases. We also optimize a rapid and simple one-pot gRNA synthesis protocol to streamline SpRYgest implementation. Together, SpRYgests can improve various DNA engineering applications that benefit from precise DNA breaks.
Collapse
Affiliation(s)
- Kathleen A Christie
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Harvard Medical School, Boston, MA, USA
| | - Jimmy A Guo
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
- Biological and Biomedical Sciences Program, Harvard University, Boston, MA, USA
| | - Rachel A Silverstein
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
- Biological and Biomedical Sciences Program, Harvard University, Boston, MA, USA
| | - Roman M Doll
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
- Molecular Biosciences/Cancer Biology Program, Heidelberg University and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | | | - Hannah E Stutzman
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
| | - Jiecong Lin
- Department of Pathology, Harvard Medical School, Boston, MA, USA
- Molecular Pathology Unit, Massachusetts General Hospital, Boston, MA, USA
- Center for Cancer Research, Massachusetts General Hospital Charlestown, Boston, MA, USA
| | - Linyuan Ma
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA
- Department of Pathology, Harvard Medical School, Boston, MA, USA
| | - Russell T Walton
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Luca Pinello
- Department of Pathology, Harvard Medical School, Boston, MA, USA
- Molecular Pathology Unit, Massachusetts General Hospital, Boston, MA, USA
- Center for Cancer Research, Massachusetts General Hospital Charlestown, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | | | - Benjamin P Kleinstiver
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA.
- Department of Pathology, Massachusetts General Hospital, Boston, MA, USA.
- Department of Pathology, Harvard Medical School, Boston, MA, USA.
| |
Collapse
|
3
|
Urbaitis T, Gasiunas G, Young JK, Hou Z, Paulraj S, Godliauskaite E, Juskeviciene MM, Stitilyte M, Jasnauskaite M, Mabuchi M, Robb GB, Siksnys V. A new family of CRISPR-type V nucleases with C-rich PAM recognition. EMBO Rep 2022; 23:e55481. [PMID: 36268581 PMCID: PMC9724661 DOI: 10.15252/embr.202255481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 09/27/2022] [Accepted: 09/29/2022] [Indexed: 12/12/2022] Open
Abstract
Most CRISPR-type V nucleases are stimulated to cleave double-stranded (ds) DNA targets by a T-rich PAM, which restricts their targeting range. Here, we identify and characterize a new family of type V RNA-guided nuclease, Cas12l, that exclusively recognizes a C-rich (5'-CCY-3') PAM. The organization of genes within its CRISPR locus is similar to type II-B CRISPR-Cas9 systems, but both sequence analysis and functional studies establish it as a new family of type V effector. Biochemical experiments show that Cas12l nucleases function optimally between 37 and 52°C, depending on the ortholog, and preferentially cut supercoiled DNA. Like other type V nucleases, it exhibits collateral nonspecific ssDNA and ssRNA cleavage activity that is triggered by ssDNA or dsDNA target recognition. Finally, we show that one family member, Asp2Cas12l, functions in a heterologous cellular environment, altogether, suggesting that this new group of CRISPR-associated nucleases may be harnessed as genome editing reagents.
Collapse
Affiliation(s)
- Tomas Urbaitis
- CasZymeVilniusLithuania,Institute of BiotechnologyVilnius UniversityVilniusLithuania
| | | | | | - Zhenglin Hou
- Farming Solutions & DigitalCorteva Agriscience™JohnstonIAUSA
| | | | | | | | - Migle Stitilyte
- CasZymeVilniusLithuania,Institute of BiotechnologyVilnius UniversityVilniusLithuania
| | - Monika Jasnauskaite
- CasZymeVilniusLithuania,Present address:
LSC‐EMBL Partnership Institute for Genome Technologies Editing, Life Sciences CenterVilnius UniversityVilniusLithuania
| | | | | | - Virginijus Siksnys
- CasZymeVilniusLithuania,Institute of BiotechnologyVilnius UniversityVilniusLithuania
| |
Collapse
|
4
|
Chan SH, Whipple JM, Dai N, Kelley TM, Withers K, Tzertzinis G, Corrêa IR, Robb GB. RNase H-based analysis of synthetic mRNA 5' cap incorporation. RNA 2022; 28:1144-1155. [PMID: 35680168 PMCID: PMC9297845 DOI: 10.1261/rna.079173.122] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
Advances in mRNA synthesis and lipid nanoparticles technologies have helped make mRNA therapeutics and vaccines a reality. The 5' cap structure is a crucial modification required to functionalize synthetic mRNA for efficient protein translation in vivo and evasion of cellular innate immune responses. The extent of 5' cap incorporation is one of the critical quality attributes in mRNA manufacturing. RNA cap analysis involves multiple steps: generation of predefined short fragments from the 5' end of the kilobase-long synthetic mRNA molecules using RNase H, a ribozyme or a DNAzyme, enrichment of the 5' cleavage products, and LC-MS intact mass analysis. In this paper, we describe (1) a framework to design site-specific RNA cleavage using RNase H; (2) a method to fluorescently label the RNase H cleavage fragments for more accessible readout methods such as gel electrophoresis or high-throughput capillary electrophoresis; (3) a simplified method for post-RNase H purification using desthiobiotinylated oligonucleotides and streptavidin magnetic beads followed by elution using water. By providing a design framework for RNase H-based RNA 5' cap analysis using less resource-intensive analytical methods, we hope to make RNA cap analysis more accessible to the scientific community.
Collapse
Affiliation(s)
- S Hong Chan
- New England Biolabs, Ipswich, Massachusetts 01938, USA
| | | | - Nan Dai
- New England Biolabs, Ipswich, Massachusetts 01938, USA
| | | | | | | | - Ivan R Corrêa
- New England Biolabs, Ipswich, Massachusetts 01938, USA
| | - G Brett Robb
- New England Biolabs, Ipswich, Massachusetts 01938, USA
| |
Collapse
|
5
|
Fuchs RT, Curcuru JL, Mabuchi M, Noireterre A, Weigele PR, Sun Z, Robb GB. Characterization of Cme and Yme thermostable Cas12a orthologs. Commun Biol 2022; 5:325. [PMID: 35388146 PMCID: PMC8986864 DOI: 10.1038/s42003-022-03275-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 03/16/2022] [Indexed: 11/16/2022] Open
Abstract
CRISPR-Cas12a proteins are RNA-guided endonucleases that cleave invading DNA containing target sequences adjacent to protospacer adjacent motifs (PAM). Cas12a orthologs have been repurposed for genome editing in non-native organisms by reprogramming them with guide RNAs to target specific sites in genomic DNA. After single-turnover dsDNA target cleavage, multiple-turnover, non-specific single-stranded DNA cleavage in trans is activated. This property has been utilized to develop in vitro assays to detect the presence of specific DNA target sequences. Most applications of Cas12a use one of three well-studied enzymes. Here, we characterize the in vitro activity of two previously unknown Cas12a orthologs. These enzymes are active at higher temperatures than widely used orthologs and have subtle differences in PAM preference, on-target cleavage, and trans nuclease activity. Together, our results enable refinement of Cas12a-based in vitro assays especially when elevated temperature is desirable.
Collapse
Affiliation(s)
- Ryan T Fuchs
- New England Biolabs Inc, Ipswich, MA, 01938, USA
| | | | | | - Audrey Noireterre
- New England Biolabs Inc, Ipswich, MA, 01938, USA
- Département de Biologie Cellulaire (BICEL), Université de Genève, CH - 1211, Genève 4, Switzerland
| | | | - Zhiyi Sun
- New England Biolabs Inc, Ipswich, MA, 01938, USA
| | - G Brett Robb
- New England Biolabs Inc, Ipswich, MA, 01938, USA.
| |
Collapse
|
6
|
Méndez-Mancilla A, Wessels HH, Legut M, Kadina A, Mabuchi M, Walker J, Robb GB, Holden K, Sanjana NE. Chemically modified guide RNAs enhance CRISPR-Cas13 knockdown in human cells. Cell Chem Biol 2022; 29:321-327.e4. [PMID: 34343484 PMCID: PMC8792099 DOI: 10.1016/j.chembiol.2021.07.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 05/17/2021] [Accepted: 07/08/2021] [Indexed: 12/26/2022]
Abstract
RNA-targeting CRISPR-Cas13 proteins have recently emerged as a powerful platform to modulate gene expression outcomes. However, protein and CRISPR RNA (crRNA) delivery in human cells can be challenging with rapid crRNA degradation yielding transient knockdown. Here we compare several chemical RNA modifications at different positions to identify synthetic crRNAs that improve RNA targeting efficiency and half-life in human cells. We show that co-delivery of modified crRNAs and recombinant Cas13 enzyme in ribonucleoprotein (RNP) complexes can alter gene expression in primary CD4+ and CD8+ T cells. This system represents a robust and efficient method to modulate transcripts without genetic manipulation.
Collapse
Affiliation(s)
- Alejandro Méndez-Mancilla
- New York Genome Center, New York, NY, USA; Department of Biology, New York University, New York, NY, USA
| | - Hans-Hermann Wessels
- New York Genome Center, New York, NY, USA; Department of Biology, New York University, New York, NY, USA
| | - Mateusz Legut
- New York Genome Center, New York, NY, USA; Department of Biology, New York University, New York, NY, USA
| | | | | | | | | | | | - Neville E Sanjana
- New York Genome Center, New York, NY, USA; Department of Biology, New York University, New York, NY, USA.
| |
Collapse
|
7
|
Mohanraju P, Mougiakos I, Albers J, Mabuchi M, Fuchs RT, Curcuru JL, van Kranenburg R, Robb GB, van der Oost J. Development of a Cas12a-Based Genome Editing Tool for Moderate Thermophiles. CRISPR J 2021; 4:82-91. [PMID: 33538626 DOI: 10.1089/crispr.2020.0086] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The ability of CRISPR-Cas12a nucleases to function reliably in a wide range of species has been key to their rapid adoption as genome engineering tools. However, so far, Cas12a nucleases have been limited for use in organisms with growth temperatures up to 37 °C. Here, we biochemically characterize three Cas12a orthologs for their temperature stability and activity. We demonstrate that Francisella novicida Cas12a (FnCas12a) has great biochemical potential for applications that require enhanced stability, including use at temperatures >37°C. Furthermore, by employing the moderate thermophilic bacterium Bacillus smithii as our experimental platform, we demonstrate that FnCas12a is active in vivo at temperatures up to 43°C. Subsequently, we develop a single-plasmid FnCas12a-based genome editing tool for B. smithii, combining the FnCas12a targeting system with plasmid-borne homologous recombination (HR) templates that carry the desired modifications. Culturing of B. smithii cells at 45°C allows for the uninhibited realization of the HR-based editing step, while a subsequent culturing step at reduced temperatures induces the efficient counterselection of the non-edited cells by FnCas12a. The developed gene-editing tool yields gene-knockout mutants within 3 days, and does not require tightly controllable expression of FnCas12a to achieve high editing efficiencies, indicating its potential for other (thermophilic) bacteria and archaea, including those with minimal genetic toolboxes. Altogether, our findings provide new biochemical insights into three widely used Cas12a nucleases, and establish the first Cas12a-based bacterial genome editing tools for moderate thermophilic microorganisms.
Collapse
Affiliation(s)
- Prarthana Mohanraju
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Ioannis Mougiakos
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Justin Albers
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | | | - Ryan T Fuchs
- New England Biolabs, Ipswich, Massachusetts, USA
| | | | - Richard van Kranenburg
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands.,Corbion, Gorinchem, The Netherlands
| | - G Brett Robb
- New England Biolabs, Ipswich, Massachusetts, USA
| | - John van der Oost
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| |
Collapse
|
8
|
Gasiunas G, Young JK, Karvelis T, Kazlauskas D, Urbaitis T, Jasnauskaite M, Grusyte MM, Paulraj S, Wang PH, Hou Z, Dooley SK, Cigan M, Alarcon C, Chilcoat ND, Bigelyte G, Curcuru JL, Mabuchi M, Sun Z, Fuchs RT, Schildkraut E, Weigele PR, Jack WE, Robb GB, Venclovas Č, Siksnys V. A catalogue of biochemically diverse CRISPR-Cas9 orthologs. Nat Commun 2020; 11:5512. [PMID: 33139742 PMCID: PMC7606464 DOI: 10.1038/s41467-020-19344-1] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 10/02/2020] [Indexed: 12/27/2022] Open
Abstract
Bacterial Cas9 nucleases from type II CRISPR-Cas antiviral defence systems have been repurposed as genome editing tools. Although these proteins are found in many microbes, only a handful of variants are used for these applications. Here, we use bioinformatic and biochemical analyses to explore this largely uncharacterized diversity. We apply cell-free biochemical screens to assess the protospacer adjacent motif (PAM) and guide RNA (gRNA) requirements of 79 Cas9 proteins, thus identifying at least 7 distinct gRNA classes and 50 different PAM sequence requirements. PAM recognition spans the entire spectrum of T-, A-, C-, and G-rich nucleotides, from single nucleotide recognition to sequence strings longer than 4 nucleotides. Characterization of a subset of Cas9 orthologs using purified components reveals additional biochemical diversity, including both narrow and broad ranges of temperature dependence, staggered-end DNA target cleavage, and a requirement for long stretches of homology between gRNA and DNA target. Our results expand the available toolset of RNA-programmable CRISPR-associated nucleases.
Collapse
Affiliation(s)
| | - Joshua K Young
- Department of Molecular Engineering, Corteva Agriscience™, Johnston, IA, 50131, USA.
| | - Tautvydas Karvelis
- Institute of Biotechnology, Vilnius University, Vilnius, LT-10257, Lithuania
| | - Darius Kazlauskas
- Institute of Biotechnology, Vilnius University, Vilnius, LT-10257, Lithuania
| | - Tomas Urbaitis
- CasZyme, Vilnius, LT-10257, Lithuania
- Institute of Biotechnology, Vilnius University, Vilnius, LT-10257, Lithuania
| | | | | | - Sushmitha Paulraj
- Department of Molecular Engineering, Corteva Agriscience™, Johnston, IA, 50131, USA
| | - Po-Hao Wang
- Department of Molecular Engineering, Corteva Agriscience™, Johnston, IA, 50131, USA
- Inari Agriculture, West Lafayette, IN, 47906, USA
| | - Zhenglin Hou
- Department of Molecular Engineering, Corteva Agriscience™, Johnston, IA, 50131, USA
| | - Shane K Dooley
- Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, 50011, USA
| | - Mark Cigan
- Department of Molecular Engineering, Corteva Agriscience™, Johnston, IA, 50131, USA
- Genus plc, Deforest, WI, 53532, USA
| | - Clara Alarcon
- Department of Molecular Engineering, Corteva Agriscience™, Johnston, IA, 50131, USA
| | - N Doane Chilcoat
- Department of Molecular Engineering, Corteva Agriscience™, Johnston, IA, 50131, USA
| | - Greta Bigelyte
- Institute of Biotechnology, Vilnius University, Vilnius, LT-10257, Lithuania
| | | | | | - Zhiyi Sun
- New England Biolabs, Ipswich, MA, 01938, USA
| | | | | | | | | | | | - Česlovas Venclovas
- Institute of Biotechnology, Vilnius University, Vilnius, LT-10257, Lithuania
| | - Virginijus Siksnys
- CasZyme, Vilnius, LT-10257, Lithuania.
- Institute of Biotechnology, Vilnius University, Vilnius, LT-10257, Lithuania.
| |
Collapse
|
9
|
Sas-Chen A, Thomas JM, Matzov D, Taoka M, Nance KD, Nir R, Bryson KM, Shachar R, Liman GLS, Burkhart BW, Gamage ST, Nobe Y, Briney CA, Levy MJ, Fuchs RT, Robb GB, Hartmann J, Sharma S, Lin Q, Florens L, Washburn MP, Isobe T, Santangelo TJ, Shalev-Benami M, Meier JL, Schwartz S. Dynamic RNA acetylation revealed by quantitative cross-evolutionary mapping. Nature 2020; 583:638-643. [PMID: 32555463 PMCID: PMC8130014 DOI: 10.1038/s41586-020-2418-2] [Citation(s) in RCA: 145] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 03/26/2020] [Indexed: 12/14/2022]
Abstract
N4-acetylcytidine (ac4C) is an ancient and highly conserved RNA modification that is present on tRNA and rRNA and has recently been investigated in eukaryotic mRNA1-3. However, the distribution, dynamics and functions of cytidine acetylation have yet to be fully elucidated. Here we report ac4C-seq, a chemical genomic method for the transcriptome-wide quantitative mapping of ac4C at single-nucleotide resolution. In human and yeast mRNAs, ac4C sites are not detected but can be induced-at a conserved sequence motif-via the ectopic overexpression of eukaryotic acetyltransferase complexes. By contrast, cross-evolutionary profiling revealed unprecedented levels of ac4C across hundreds of residues in rRNA, tRNA, non-coding RNA and mRNA from hyperthermophilic archaea. Ac4C is markedly induced in response to increases in temperature, and acetyltransferase-deficient archaeal strains exhibit temperature-dependent growth defects. Visualization of wild-type and acetyltransferase-deficient archaeal ribosomes by cryo-electron microscopy provided structural insights into the temperature-dependent distribution of ac4C and its potential thermoadaptive role. Our studies quantitatively define the ac4C landscape, providing a technical and conceptual foundation for elucidating the role of this modification in biology and disease4-6.
Collapse
Affiliation(s)
- Aldema Sas-Chen
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Justin M Thomas
- National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Donna Matzov
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Masato Taoka
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan
| | - Kellie D Nance
- National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Ronit Nir
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Keri M Bryson
- National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Ran Shachar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Geraldy L S Liman
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Brett W Burkhart
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | | | - Yuko Nobe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan
| | - Chloe A Briney
- National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | | | - Ryan T Fuchs
- RNA Research Division, New England Biolabs, Inc, Ipswich, MA, USA
| | - G Brett Robb
- RNA Research Division, New England Biolabs, Inc, Ipswich, MA, USA
| | - Jesse Hartmann
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Sunny Sharma
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, USA
| | - Qishan Lin
- RNA Epitranscriptomics and Proteomics Resource, University at Albany, Albany, NY, USA
| | | | | | - Toshiaki Isobe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan
| | - Thomas J Santangelo
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Moran Shalev-Benami
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel.
| | - Jordan L Meier
- National Cancer Institute, National Institutes of Health, Frederick, MD, USA.
| | - Schraga Schwartz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
| |
Collapse
|
10
|
|
11
|
Fu BXH, Smith JD, Fuchs RT, Mabuchi M, Curcuru J, Robb GB, Fire AZ. Target-dependent nickase activities of the CRISPR-Cas nucleases Cpf1 and Cas9. Nat Microbiol 2019; 4:888-897. [PMID: 30833733 PMCID: PMC6512873 DOI: 10.1038/s41564-019-0382-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 01/21/2019] [Indexed: 12/26/2022]
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR) machineries are prokaryotic immune systems that have been adapted as versatile gene editing and manipulation tools. We found that CRISPR nucleases from two families, Cpf1 (also known as Cas12a) and Cas9, exhibit differential guide RNA (gRNA) sequence requirements for cleavage of the two strands of target DNA in vitro. As a consequence of the differential gRNA requirements, both Cas9 and Cpf1 enzymes can exhibit potent nickase activities on an extensive class of mismatched double-stranded DNA (dsDNA) targets. These properties allow the production of efficient nickases for a chosen dsDNA target sequence, without modification of the nuclease protein, using gRNAs with a variety of patterns of mismatch to the intended DNA target. In parallel to the nicking activities observed with purified Cas9 in vitro, we observed sequence-dependent nicking for both perfectly matched and partially mismatched target sequences in a Saccharomyces cerevisiae system. Our findings have implications for CRISPR spacer acquisition, off-target potential of CRISPR gene editing/manipulation, and tool development using homology-directed nicking.
Collapse
Affiliation(s)
- Becky Xu Hua Fu
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA.
| | - Justin D Smith
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | | | | | | | | | - Andrew Z Fire
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA.
| |
Collapse
|
12
|
Yourik P, Fuchs RT, Mabuchi M, Curcuru JL, Robb GB. Staphylococcus aureus Cas9 is a multiple-turnover enzyme. RNA 2019; 25:35-44. [PMID: 30348755 PMCID: PMC6298560 DOI: 10.1261/rna.067355.118] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Accepted: 10/18/2018] [Indexed: 05/21/2023]
Abstract
Cas9 nuclease is the key effector of type II CRISPR adaptive immune systems found in bacteria. The nuclease can be programmed by a single guide RNA (sgRNA) to cleave DNA in a sequence-specific manner. This property has led to its widespread adoption as a genome editing tool in research laboratories and holds great promise for biotechnological and therapeutic applications. The general mechanistic features of catalysis by Cas9 homologs are comparable; however, a high degree of diversity exists among the protein sequences, which may result in subtle mechanistic differences. S. aureus (SauCas9) and especially S. pyogenes (SpyCas9) are among the best-characterized Cas9 proteins and share ∼17% sequence identity. A notable feature of SpyCas9 is an extremely slow rate of reaction turnover, which is thought to limit the amount of substrate DNA cleavage. Using in vitro biochemistry and enzyme kinetics, we directly compare SpyCas9 and SauCas9 activities. Here, we report that in contrast to SpyCas9, SauCas9 is a multiple-turnover enzyme, which to our knowledge is the first report of such activity in a Cas9 homolog. We also show that DNA cleaved with SauCas9 does not undergo any detectable single-stranded degradation after the initial double-stranded break observed previously with SpyCas9, thus providing new insights and considerations for future design of CRISPR/Cas9-based applications.
Collapse
Affiliation(s)
- Paul Yourik
- RNA and Genome Editing, New England Biolabs Inc., Ipswich, Massachusetts 01938, USA
| | - Ryan T Fuchs
- RNA and Genome Editing, New England Biolabs Inc., Ipswich, Massachusetts 01938, USA
| | - Megumu Mabuchi
- RNA and Genome Editing, New England Biolabs Inc., Ipswich, Massachusetts 01938, USA
| | - Jennifer L Curcuru
- RNA and Genome Editing, New England Biolabs Inc., Ipswich, Massachusetts 01938, USA
| | - G Brett Robb
- RNA and Genome Editing, New England Biolabs Inc., Ipswich, Massachusetts 01938, USA
| |
Collapse
|
13
|
Ramanathan A, Robb GB, Chan SH. mRNA capping: biological functions and applications. Nucleic Acids Res 2016; 44:7511-26. [PMID: 27317694 PMCID: PMC5027499 DOI: 10.1093/nar/gkw551] [Citation(s) in RCA: 439] [Impact Index Per Article: 54.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/03/2016] [Indexed: 12/19/2022] Open
Abstract
The 5′ m7G cap is an evolutionarily conserved modification of eukaryotic mRNA. Decades of research have established that the m7G cap serves as a unique molecular module that recruits cellular proteins and mediates cap-related biological functions such as pre-mRNA processing, nuclear export and cap-dependent protein synthesis. Only recently has the role of the cap 2′O methylation as an identifier of self RNA in the innate immune system against foreign RNA has become clear. The discovery of the cytoplasmic capping machinery suggests a novel level of control network. These new findings underscore the importance of a proper cap structure in the synthesis of functional messenger RNA. In this review, we will summarize the current knowledge of the biological roles of mRNA caps in eukaryotic cells. We will also discuss different means that viruses and their host cells use to cap their RNA and the application of these capping machineries to synthesize functional mRNA. Novel applications of RNA capping enzymes in the discovery of new RNA species and sequencing the microbiome transcriptome will also be discussed. We will end with a summary of novel findings in RNA capping and the questions these findings pose.
Collapse
Affiliation(s)
- Anand Ramanathan
- New England Biolabs, Inc. 240 County Road, Ipswich, MA 01938, USA
| | - G Brett Robb
- New England Biolabs, Inc. 240 County Road, Ipswich, MA 01938, USA
| | - Siu-Hong Chan
- New England Biolabs, Inc. 240 County Road, Ipswich, MA 01938, USA
| |
Collapse
|
14
|
Fuchs RT, Sun Z, Zhuang F, Robb GB. Bias in ligation-based small RNA sequencing library construction is determined by adaptor and RNA structure. PLoS One 2015; 10:e0126049. [PMID: 25942392 PMCID: PMC4420488 DOI: 10.1371/journal.pone.0126049] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 03/28/2015] [Indexed: 01/01/2023] Open
Abstract
High-throughput sequencing (HTS) has become a powerful tool for the detection of and sequence characterization of microRNAs (miRNA) and other small RNAs (sRNA). Unfortunately, the use of HTS data to determine the relative quantity of different miRNAs in a sample has been shown to be inconsistent with quantitative PCR and Northern Blot results. Several recent studies have concluded that the major contributor to this inconsistency is bias introduced during the construction of sRNA libraries for HTS and that the bias is primarily derived from the adaptor ligation steps, specifically where single stranded adaptors are sequentially ligated to the 3’ and 5’-end of sRNAs using T4 RNA ligases. In this study we investigated the effects of ligation bias by using a pool of randomized ligation substrates, defined mixtures of miRNA sequences and several combinations of adaptors in HTS library construction. We show that like the 3’ adaptor ligation step, the 5’ adaptor ligation is also biased, not because of primary sequence, but instead due to secondary structures of the two ligation substrates. We find that multiple secondary structural factors influence final representation in HTS results. Our results provide insight about the nature of ligation bias and allowed us to design adaptors that reduce ligation bias and produce HTS results that more accurately reflect the actual concentrations of miRNAs in the defined starting material.
Collapse
Affiliation(s)
- Ryan T. Fuchs
- RNA Research Division, New England Biolabs Incorporated, Ipswich, Massachusetts, United States of America
| | - Zhiyi Sun
- RNA Research Division, New England Biolabs Incorporated, Ipswich, Massachusetts, United States of America
| | - Fanglei Zhuang
- RNA Research Division, New England Biolabs Incorporated, Ipswich, Massachusetts, United States of America
| | - G. Brett Robb
- RNA Research Division, New England Biolabs Incorporated, Ipswich, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
15
|
Ho JJD, Metcalf JL, Yan MS, Turgeon PJ, Wang JJ, Chalsev M, Petruzziello-Pellegrini TN, Tsui AKY, He JZ, Dhamko H, Man HSJ, Robb GB, Teh BT, Ohh M, Marsden PA. Functional importance of Dicer protein in the adaptive cellular response to hypoxia. J Biol Chem 2012; 287:29003-20. [PMID: 22745131 PMCID: PMC3436557 DOI: 10.1074/jbc.m112.373365] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 06/19/2012] [Indexed: 01/06/2023] Open
Abstract
The processes by which cells sense and respond to ambient oxygen concentration are fundamental to cell survival and function, and they commonly target gene regulatory events. To date, however, little is known about the link between the microRNA pathway and hypoxia signaling. Here, we show in vitro and in vivo that chronic hypoxia impairs Dicer (DICER1) expression and activity, resulting in global consequences on microRNA biogenesis. We show that von Hippel-Lindau-dependent down-regulation of Dicer is key to the expression and function of hypoxia-inducible factor α (HIF-α) subunits. Specifically, we show that EPAS1/HIF-2α is regulated by the Dicer-dependent microRNA miR-185, which is down-regulated by hypoxia. Full expression of hypoxia-responsive/HIF target genes in chronic hypoxia (e.g. VEGFA, FLT1/VEGFR1, KDR/VEGFR2, BNIP3L, and SLC2A1/GLUT1), the function of which is to regulate various adaptive responses to compromised oxygen availability, is also dependent on hypoxia-mediated down-regulation of Dicer function and changes in post-transcriptional gene regulation. Therefore, functional deficiency of Dicer in chronic hypoxia is relevant to both HIF-α isoforms and hypoxia-responsive/HIF target genes, especially in the vascular endothelium. These findings have relevance to emerging therapies given that we show that the efficacy of RNA interference under chronic hypoxia, but not normal oxygen availability, is Dicer-dependent. Collectively, these findings show that the down-regulation of Dicer under chronic hypoxia is an adaptive mechanism that serves to maintain the cellular hypoxic response through HIF-α- and microRNA-dependent mechanisms, thereby providing an essential mechanistic insight into the oxygen-dependent microRNA regulatory pathway.
Collapse
Affiliation(s)
- J. J. David Ho
- From the Departments of Medical Biophysics and
- Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Ontario M5B 1W8, Canada
| | | | - Matthew S. Yan
- From the Departments of Medical Biophysics and
- Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Ontario M5B 1W8, Canada
| | - Paul J. Turgeon
- Laboratory Medicine and Pathobiology and
- Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Ontario M5B 1W8, Canada
| | - Jenny Jing Wang
- Laboratory Medicine and Pathobiology and
- Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Ontario M5B 1W8, Canada
| | - Maria Chalsev
- Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Ontario M5B 1W8, Canada
| | - Tania N. Petruzziello-Pellegrini
- Laboratory Medicine and Pathobiology and
- Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Ontario M5B 1W8, Canada
| | - Albert K. Y. Tsui
- Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Ontario M5B 1W8, Canada
| | - Jeff Z. He
- Laboratory Medicine and Pathobiology and
| | - Helena Dhamko
- Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Ontario M5B 1W8, Canada
| | - H. S. Jeffrey Man
- Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Ontario M5B 1W8, Canada
| | - G. Brett Robb
- Division of RNA Biology, New England Biolabs, Ipswich, Massachusetts 01938-2723, and
| | - Bin T. Teh
- Van Andel Research Institute, Grand Rapids, Michigan 49503
| | | | - Philip A. Marsden
- From the Departments of Medical Biophysics and
- Laboratory Medicine and Pathobiology and
- Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Ontario M5B 1W8, Canada
| |
Collapse
|
16
|
Abstract
T4 RNA ligases are commonly used to attach adapters to RNAs, but large differences in ligation efficiency make detection and quantitation problematic. We developed a ligation selection strategy using random RNAs in combination with high-throughput sequencing to gain insight into the differences in efficiency of ligating pre-adenylated DNA adapters to RNA 3′-ends. After analyzing biases in RNA sequence, secondary structure and RNA-adapter cofold structure, we conclude that T4 RNA ligases do not show significant primary sequence preference in RNA substrates, but are biased against structural features within RNAs and adapters. Specifically, RNAs with less than three unstructured nucleotides at the 3′-end and RNAs that are predicted to cofold with an adapter in unfavorable structures are likely to be poorly ligated. The effect of RNA-adapter cofold structures on ligation is supported by experiments where the ligation efficiency of specific miRNAs was changed by designing adapters to alter cofold structure. In addition, we show that using adapters with randomized regions results in higher ligation efficiency and reduced ligation bias. We propose that using randomized adapters may improve RNA representation in experiments that include a 3′-adapter ligation step.
Collapse
|
17
|
Munafó DB, Robb GB. Optimization of enzymatic reaction conditions for generating representative pools of cDNA from small RNA. RNA 2010; 16:2537-52. [PMID: 20921270 PMCID: PMC2995414 DOI: 10.1261/rna.2242610] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 08/30/2010] [Indexed: 05/23/2023]
Abstract
Small regulatory RNA repertoires in biological samples are heterogeneous mixtures that may include species arising from varied biosynthetic pathways and modification events. Small RNA profiling and discovery approaches ought to capture molecules in a way that is representative of expression level. It follows that the effects of RNA modifications on representation should be minimized. The collection of high-quality, representative data, therefore, will be highly dependent on bias-free sample manipulation in advance of quantification. We examined the impact of 2'-O-methylation of the 3'-terminal nucleotide of small RNA on key enzymatic reactions of standard front-end manipulation schemes. Here we report that this common modification negatively influences the representation of these small RNA species. Deficits occurred at multiple steps as determined by gel analysis of synthetic input RNA and by quantification and sequencing of derived cDNA pools. We describe methods to minimize the effects of 2'-O-methyl modification of small RNA 3'-termini using T4 RNA ligase 2 truncated, and other optimized reaction conditions, demonstrating their use by quantifying representation of miRNAs and piRNAs in cDNA pools prepared from biological samples.
Collapse
|
18
|
Teichert AM, Scott JA, Robb GB, Zhou YQ, Zhu SN, Lem M, Keightley A, Steer BM, Schuh AC, Adamson SL, Cybulsky MI, Marsden PA. Endothelial nitric oxide synthase gene expression during murine embryogenesis: commencement of expression in the embryo occurs with the establishment of a unidirectional circulatory system. Circ Res 2008; 103:24-33. [PMID: 18556578 DOI: 10.1161/circresaha.107.168567] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To elucidate the role of endothelial NO synthase (eNOS)-derived NO during mammalian embryogenesis, we assessed the expression of the eNOS gene during development. Using transgenic eNOS promoter/reporter mice (with beta-galactosidase and green fluorescent protein reporters), in situ cRNA hybridization, and immunohistochemistry to assess transcription, steady-state mRNA levels, and protein expression, respectively, we noted that eNOS expression in the developing cardiovascular system was highly restricted to endothelial cells of medium- and large-sized arteries and the endocardium. The onset of transcription of the native eNOS gene and reporters coincided with the establishment of robust, unidirectional blood flow at embryonic day 9.5, as assessed by Doppler ultrasound biomicroscopy. Interestingly, reporter transgene expression and native eNOS mRNA were also observed in discrete regions of the developing skeletal musculature and the apical ectodermal ridge of developing limbs, suggesting a role for eNOS-derived NO in limb development. In vitro studies of promoter/reporter constructs indicated that similar eNOS promoter regions operate in both embryonic skeletal muscle and vascular endothelial cells. In summary, transcriptional activity of the eNOS gene in the murine circulatory system occurred following the establishment of embryonic blood flow. Thus, the eNOS gene is a late-onset gene in endothelial ontogeny.
Collapse
Affiliation(s)
- Anouk-Martine Teichert
- Renal Division and Department of Medicine, St. Michael's Hospital, Department of Medicine, University of Toronto, Toronto, Canada
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Robb GB, Rana TM. RNA helicase A interacts with RISC in human cells and functions in RISC loading. Mol Cell 2007; 26:523-37. [PMID: 17531811 DOI: 10.1016/j.molcel.2007.04.016] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2006] [Revised: 02/16/2007] [Accepted: 04/23/2007] [Indexed: 12/22/2022]
Abstract
RNA interference is a conserved pathway of sequence-specific gene silencing that depends on small guide RNAs and the action of proteins assembled in the RNA-induced silencing complex (RISC). Minimally, the action of RISC requires the endonucleolytic slicer activity of Argonaute2 (Ago2) directed to RNA targets whose sequences are complementary to RISC-incorporated small RNA. To identify RISC components in human cells, we developed an affinity-purification strategy to isolate siRNA-programmed RISC. Here we report the identification of RNA helicase A (RHA) as a human RISC-associated factor. We show that RHA interacts in human cells with siRNA, Ago2, TRBP, and Dicer and functions in the RNAi pathway. In RHA-depleted cells, RNAi was reduced as a consequence of decreased intracellular concentration of active RISC assembled with the guide-strand RNA and Ago2. Our results identify RHA as a RISC component and demonstrate that RHA functions in RISC as an siRNA-loading factor.
Collapse
Affiliation(s)
- G Brett Robb
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | | |
Collapse
|
20
|
Wichroski MJ, Robb GB, Rana TM. Human retroviral host restriction factors APOBEC3G and APOBEC3F localize to mRNA processing bodies. PLoS Pathog 2006; 2:e41. [PMID: 16699599 PMCID: PMC1458959 DOI: 10.1371/journal.ppat.0020041] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Accepted: 04/03/2006] [Indexed: 12/22/2022] Open
Abstract
APOBEC3G is an antiviral host factor capable of inhibiting the replication of both exogenous and endogenous retroviruses as well as hepatitis B, a DNA virus that replicates through an RNA intermediate. To gain insight into the mechanism whereby APOBEC3G restricts retroviral replication, we investigated the subcellular localization of the protein. Herein, we report that APOBEC3G localizes to mRNA processing (P) bodies, cytoplasmic compartments involved in the degradation and storage of nontranslating mRNAs. Biochemical analysis revealed that APOBEC3G localizes to a ribonucleoprotein complex with other P-body proteins which have established roles in cap-dependent translation (eIF4E and eIF4E-T), translation suppression (RCK/p54), RNA interference–mediated post-transcriptional gene silencing (AGO2), and decapping of mRNA (DCP2). Similar analysis with other APOBEC3 family members revealed a potential link between the localization of APOBEC3G and APOBEC3F to a common ribonucleoprotein complex and P-bodies with potent anti–HIV-1 activity. In addition, we present evidence suggesting that an important role for HIV-1 Vif, which subverts both APOBEC3G and APOBEC3F antiviral function by inducing their degradation, could be to selectively remove these proteins from and/or restrict their localization to P-bodies. Taken together, the results of this study reveal a novel link between innate immunity against retroviruses and P-bodies suggesting that APOBEC3G and APOBEC3F could function in the context of P-bodies to restrict HIV-1 replication. Successful replication of viruses and other intracellular pathogens in their respective host cells requires that they overcome a series of replication restrictions or “roadblocks” established by the cell. In the case of HIV-1, the ability of the virus to replicate in human cells is dependent on its ability to neutralize APOBEC3G, a DNA editing enzyme that incorporates into virions and renders them noninfectious. Although a potentially devastating inhibitor of HIV-1 replication, the virus evades APOBEC3G by inducing its degradation during virus assembly. APOBEC3G is also capable of inhibiting the replication of other retroviruses as well as the hepadnavirus hepatitis B, a DNA virus that replicates through an RNA intermediate, suggesting that APOBEC3G may function in cellular defense against a broad range of viral pathogens. Here, Rana and colleagues present their findings that APOBEC3G localizes to specialized compartments in the cytoplasm of mammalian cells known as mRNA processing (P) bodies, which function in the degradation and storage of cellular mRNA. Furthermore, they show that APOBEC3G assembles into a ribonucleoprotein complex with P-body proteins involved in translation, translation suppression, RNA interference, and mRNA decapping. These novel and exciting findings have broad-scale implications for APOBEC3G function and for the role of P-bodies in both cellular defense against viruses and retroviral assembly.
Collapse
Affiliation(s)
- Michael J Wichroski
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - G. Brett Robb
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Tariq M Rana
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
21
|
Robb GB, Brown KM, Khurana J, Rana TM. Specific and potent RNAi in the nucleus of human cells. Nat Struct Mol Biol 2005; 12:133-7. [PMID: 15643423 DOI: 10.1038/nsmb886] [Citation(s) in RCA: 240] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Accepted: 12/16/2004] [Indexed: 12/31/2022]
Abstract
RNA interference (RNAi) has become a research tool to control gene expression in various organisms and holds potential as a new therapeutic strategy. The mechanism of small interfering RNA (siRNA)-mediated RNAi involves target mRNA cleavage and destruction in the cytoplasm. We investigated siRNA-mediated induction of RNAi in the nucleus of human cells. Notably, we observed highly efficient knockdown of small nuclear RNA 7SK by siRNA. siRNA- and microRNA-programmed RNA-induced silencing complexes (RISCs) were present in both cytoplasmic and nuclear compartments and specifically cleaved their perfectly matched target RNA with markedly high efficiencies. Our results provide the first evidence that human RISCs programmed with siRNA are present in the nucleus and can knock down target RNA levels. These studies reveal new roles for the RNAi machinery in modulating post-transcriptional gene expression in the nucleus.
Collapse
Affiliation(s)
- G Brett Robb
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | | | | | | |
Collapse
|
22
|
Robb GB, Carson AR, Tai SC, Fish JE, Singh S, Yamada T, Scherer SW, Nakabayashi K, Marsden PA. Post-transcriptional regulation of endothelial nitric-oxide synthase by an overlapping antisense mRNA transcript. J Biol Chem 2004; 279:37982-96. [PMID: 15234981 DOI: 10.1074/jbc.m400271200] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Endothelial nitric-oxide synthase (eNOS) mRNA levels are abnormal in diseases of the cardiovascular system, but changes in gene expression cannot be accounted for by transcription alone. We found evidence for the existence of an antisense mRNA (sONE) that is derived from a transcription unit (NOS3AS) on the opposite DNA strand from which the human eNOS (NOS3) mRNA is transcribed at human chromosome 7q36. The genes are oriented in a tail-to-tail configuration, and the mRNAs encoding sONE and eNOS are complementary for 662 nucleotides. The mRNA for sONE could be detected in a variety of cell types, both in vivo and in vitro, but not vascular endothelial cells. In contrast, expression of eNOS is highly restricted to vascular endothelium. Most surprisingly, interrogation of transcriptional events across NOS3/NOS3AS genomic regions, using single- and double-stranded probes for nuclear run-off analyses and chromatin immunoprecipitation-based assessments of RNA polymerase II distribution, indicated that NOS3 and NOS3AS gene transcription did not correlate with steady-state mRNA levels. We found strong evidence supporting a role for NOS3AS in the post-transcriptional regulation of NOS3 expression. RNA interference-mediated inhibition of sONE expression in vascular smooth muscle cells increased eNOS expression. Overexpression of sONE in endothelial cells blunted eNOS expression. Finally, the histone deacetylase inhibitor trichostatin A is known to regulate the expression of eNOS via a post-transcriptional mechanism. We found that trichostatin A treatment of vascular endothelial cells increased expression of sONE mRNA levels prior to the observed decrease in eNOS mRNA expression. Taken together, these results indicate that an antisense mRNA (sONE) participates in the post-transcriptional regulation of eNOS and provide a newer model for endothelial cell-specific gene expression.
Collapse
Affiliation(s)
- G Brett Robb
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Chan Y, Fish JE, D'Abreo C, Lin S, Robb GB, Teichert AM, Karantzoulis-Fegaras F, Keightley A, Steer BM, Marsden PA. The cell-specific expression of endothelial nitric-oxide synthase: a role for DNA methylation. J Biol Chem 2004; 279:35087-100. [PMID: 15180995 DOI: 10.1074/jbc.m405063200] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The basis for the endothelial cell-restricted expression of endothelial nitric-oxide synthase (eNOS) is not known. While transgenic promoter/reporter mice demonstrated endothelium cell-specific eNOS expression, we found robust expression of episomal eNOS promoter/reporter constructs in cell types that do not express the native eNOS transcript. To explore the mechanism underlying this differential activity pattern of chromatin-versus episome-based eNOS promoters, we examined the methylation status of 5'-regulatory sequences of the human eNOS gene. DNA methylation differed dramatically between endothelial and nonendothelial cell types, including vascular smooth muscle cells. This same cell type-specific methylation pattern was observed in vivo in endothelial and vascular smooth muscle cells of the mouse aorta at the native murine eNOS promoter. We addressed the functional consequences of methylation on eNOS transcription using transient transfection of in vitro methylated promoter/reporter constructs and found that methylated constructs exhibited a marked decrease in the synergistic action of Sp1, Sp3, and Ets1 on eNOS promoter activity. The addition of methyl-CpG-binding protein 2 further reduced the transcriptional activity of methylated eNOS constructs. Importantly, chromatin immunoprecipitation demonstrated the presence of Sp1, Sp3, and Ets1 at the native eNOS promoter in endothelial cells but not in vascular smooth muscle cells. Finally, robust expression of eNOS mRNA was induced in nonendothelial cell types following inhibition of DNA methyltransferase activity with 5-azacytidine, demonstrating the importance of DNA methylation-mediated repression. This report is the first to show that promoter DNA methylation plays an important role in the cell-specific expression of a constitutively expressed gene in the vascular endothelium.
Collapse
MESH Headings
- Animals
- Aorta/pathology
- Azacitidine/pharmacology
- Cattle
- Cell Line
- Cell Line, Tumor
- Cells, Cultured
- Chromatin/metabolism
- CpG Islands
- DNA Methylation
- DNA-Binding Proteins/metabolism
- Drosophila
- Endothelium, Vascular/cytology
- Endothelium, Vascular/metabolism
- Genes, Reporter
- Genetic Vectors
- Humans
- Jurkat Cells
- Luciferases/metabolism
- Mice
- Muscle, Smooth, Vascular/metabolism
- Nitric Oxide Synthase/biosynthesis
- Nitric Oxide Synthase Type II
- Nitric Oxide Synthase Type III
- Precipitin Tests
- Promoter Regions, Genetic
- Proto-Oncogene Protein c-ets-1
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-ets
- RNA, Messenger/metabolism
- Ribonucleases/metabolism
- Sp1 Transcription Factor/metabolism
- Sp3 Transcription Factor
- Sulfites/pharmacology
- Transcription Factors/metabolism
- Transcription, Genetic
- Transfection
Collapse
Affiliation(s)
- Yvonne Chan
- Renal Division and Department of Medicine, St. Michael's Hospital and University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Mawji IA, Robb GB, Tai SC, Marsden PA. Role of the 3'-untranslated region of human endothelin-1 in vascular endothelial cells. Contribution to transcript lability and the cellular heat shock response. J Biol Chem 2004; 279:8655-67. [PMID: 14660616 DOI: 10.1074/jbc.m312190200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endothelin-1 (ET-1) is a potent vasoconstrictor peptide expressed in the vascular endothelium. Stringent control over ET-1 expression is achieved through a highly regulated promoter and rapid mRNA turnover. Since little is known about mechanisms governing ET-1 post-transcriptional regulation, and changes in ET-1 mRNA stability are implicated in disease processes, we characterized these pathways using a variety of functional approaches. We expressed human ET-1 and luciferase transcripts with or without a wild type ET-1 3'-untranslated region (3'-UTR) and found that the 3'-UTR had potent mRNA destabilizing activity. Deletion analysis localized this activity to two domains of the 3'-UTR we have termed destabilizing elements 1 and 2 (DE1 and DE2). Mutational studies revealed that DE1 functions as an AU-rich element (ARE) dependent on a 100-nucleotide region. This activity was further localized to a 10-nucleotide region at position 978-987 of the 3'-UTR. Depletion of AUF1 by RNA interference up-regulated ET-1 in endothelial cells suggesting AUF1-dependent regulation. Since AUF1 functions through the ubiquitin-proteasome pathway, we disrupted this pathway with heat shock and proteasome inhibitor in endothelial cells and observed stabilization of endogenous ET-1 mRNA. Chimeric transcripts bearing wild type ET-1 3'-UTRs were also stabilized in response to proteasome inhibition whereas DE1 mutants failed to respond. Taken together, these findings suggest a complex model of ARE-mediated mRNA turnover dependent on two 3'-UTR domains, DE1 and DE2. Furthermore, DE1 functions as an ARE directing mRNA half-life through the proteasome. Finally, this data provides evidence for a novel pathway of ET-1 mRNA stabilization by heat shock.
Collapse
Affiliation(s)
- Imtiaz A Mawji
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Canada
| | | | | | | |
Collapse
|
25
|
Abstract
Advances in our understanding of the molecular mechanisms involved in the constitutive and regulated expression of endothelial nitric oxide synthase (eNOS) mRNA expression present a new level of complexity to the study of endothelial gene regulation in health and disease. Recent studies highlight the contribution of both transcription and RNA stability to net steady-state mRNA levels of eNOS in vascular endothelium, introducing a new paradigm to gene regulation in the injured blood vessel. Constitutive eNOS expression is dependent on basal transcription machinery in the core promoter, involving positive and negative protein–protein and protein–DNA interactions. Chromatin-based mechanisms and epigenetic events also regulate expression of eNOS at the transcriptional level in a cell-restricted fashion. Although constitutively active, important physiological and pathophysiologic stimuli alter eNOS gene transcription rates. For instance, eNOS transcription rates increase in response to lysophosphatidylcholine, shear stress, and TGF-β, among others. Under basal conditions, eNOS mRNA is extremely stable. Surprisingly, posttranscriptional mechanisms have emerged as important regulatory pathways in the observed decreases in eNOS expression in some settings. In models of inflammation, proliferation/injury, oxidized low-density lipoprotein treatment, and hypoxia, eNOS mRNA destabilization plays a significant role in the rapid downregulation of eNOS mRNA levels.
Collapse
Affiliation(s)
- Sharon C Tai
- Renal Division and Department of Medicine, St. Michael's Hospital and University of Toronto, Ontario, Canada
| | | | | |
Collapse
|
26
|
Newton DC, Bevan SC, Choi S, Robb GB, Millar A, Wang Y, Marsden PA. Translational regulation of human neuronal nitric-oxide synthase by an alternatively spliced 5'-untranslated region leader exon. J Biol Chem 2003; 278:636-44. [PMID: 12403769 DOI: 10.1074/jbc.m209988200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of the neuronal nitric-oxide synthase (nNOS) mRNA is subject to complex cell-specific transcriptional regulation, which is mediated by alternative promoters. Unexpectedly, we identified a 89-nucleotide alternatively spliced exon located in the 5'-untranslated region between exon 1 variants and a common exon 2 that contains the translational initiation codon. Alternative splicing events that do not affect the open reading frame are distinctly uncommon in mammals; therefore, we assessed its functional relevance. Transient transfection of reporter RNAs performed in a variety of cell types revealed that this alternatively spliced exon acts as a potent translational repressor. Stably transfected cell lines confirmed that the alternatively spliced exon inhibited translation of the native nNOS open reading frame. Reverse transcription-PCR and RNase protection assays indicated that nNOS mRNAs containing this exon are common and expressed in both a promoter-specific and tissue-restricted fashion. Mutational analysis identified the functional cis-element within this novel exon, and a secondary structure prediction revealed that it forms a putative stem-loop. RNA electrophoretic mobility shift assay techniques revealed that a specific cytoplasmic RNA-binding complex interacts with this motif. Hence, a unique splicing event within a 5'-untranslated region is demonstrated to introduce a translational control element. This represents a newer model for the translational control of a mammalian mRNA.
Collapse
Affiliation(s)
- Derek C Newton
- Renal Division and the Department of Medicine, St. Michael's Hospital and University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | | | | | | | | | | | | |
Collapse
|
27
|
Teichert AM, Miller TL, Tai SC, Wang Y, Bei X, Robb GB, Phillips MJ, Marsden PA. In vivo expression profile of an endothelial nitric oxide synthase promoter-reporter transgene. Am J Physiol Heart Circ Physiol 2000; 278:H1352-61. [PMID: 10749733 DOI: 10.1152/ajpheart.2000.278.4.h1352] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endothelium-derived nitric oxide (NO) is primarily attributable to constitutive expression of the endothelial nitric oxide synthase (eNOS) gene. Although a more comprehensive understanding of transcriptional regulation of eNOS is emerging with respect to in vitro regulatory pathways, their relevance in vivo warrants assessment. In this regard, promoter-reporter insertional transgenic murine lines were created containing 5,200 bp of the native murine eNOS promoter directing transcription of nuclear-localized beta-galactosidase. Examination of beta-galactosidase expression in heart, lung, kidney, liver, spleen, and brain of adult mice demonstrated robust signal in large and medium-sized blood vessels. Small arterioles, capillaries, and venules of the microvasculature were notably negative, with the exception of the vasa recta of the medullary circulation of the kidney, which was strongly positive. Only in the brain was the reporter expressed in non-endothelial cell types, such as the CA1 region of the hippocampus. Epithelial cells of the bronchi, bronchioles, and alveoli were scored as negative, as was renal tubular epithelium. Cardiac myocytes, skeletal muscle, and smooth muscle of both vascular and nonvascular sources failed to demonstrate beta-galactosidase staining. Expression was uniform across multiple founders and was not significantly affected by genomic integration site. These transgenic eNOS promoter-reporter lines will be a valuable resource for ongoing studies addressing the regulated expression of eNOS in vivo in both health and disease.
Collapse
Affiliation(s)
- A M Teichert
- Department of Medicine, St. Michael's Hospital and University of Toronto, Toronto M5S 1A8, Ontario, Canada M5S 1X8
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Wang Y, Newton DC, Robb GB, Kau CL, Miller TL, Cheung AH, Hall AV, VanDamme S, Wilcox JN, Marsden PA. RNA diversity has profound effects on the translation of neuronal nitric oxide synthase. Proc Natl Acad Sci U S A 1999; 96:12150-5. [PMID: 10518591 PMCID: PMC18427 DOI: 10.1073/pnas.96.21.12150] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A comprehensive analysis of the structure of neuronal nitric oxide synthase (nNOS; EC 1.14.13.39) mRNA species revealed NOS1 to be the most structurally diverse human gene described to date in terms of promoter usage. Nine unique exon 1 variants are variously used for transcript initiation in diverse tissues, and each is expressed from a unique 5'-flanking region. The dependence on unique genomic regions to control transcription initiation in a cell-specific fashion burdens the transcripts with complex 5'-mRNA leader sequences. Elaborate splicing patterns that involve alternatively spliced leader exons and exon skipping have been superimposed on this diversity. Highly structured nNOS mRNA 5'-untranslated regions, which have profound effects on translation both in vitro and in cells, contain cis RNA elements that modulate translational efficiency in response to changes in cellular phenotype.
Collapse
Affiliation(s)
- Y Wang
- Renal Division and Department of Medicine, St. Michael's Hospital, University of Toronto, Toronto, ON M4X 1B1, Canada
| | | | | | | | | | | | | | | | | | | |
Collapse
|