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Articles 1 - 12 of 12

Full-Text Articles in Molecular Biology

Nmecas9 Is An Intrinsically High-Fidelity Genome Editing Platform, Nadia Amrani, Xin D. Gao, Pengpeng Liu, Alireza Edraki, Aamir Mir, Raed Ibraheim, Ankit Gupta, Kanae E. Sasaki, Tong Wu, Thomas G. Fazzio, Lihua Julie Zhu, Scot A. Wolfe, Erik J. Sontheimer May 2018

Nmecas9 Is An Intrinsically High-Fidelity Genome Editing Platform, Nadia Amrani, Xin D. Gao, Pengpeng Liu, Alireza Edraki, Aamir Mir, Raed Ibraheim, Ankit Gupta, Kanae E. Sasaki, Tong Wu, Thomas G. Fazzio, Lihua Julie Zhu, Scot A. Wolfe, Erik J. Sontheimer

University of Massachusetts Medical School Faculty Publications

Background: The development of CRISPR genome editing has transformed biomedical research. Most applications reported thus far rely upon the Cas9 protein from Streptococcus pyogenes SF370 (SpyCas9). With many RNA guides, wild-type SpyCas9 can induce significant levels of unintended mutations at near-cognate sites, necessitating substantial efforts toward the development of strategies to minimize off-target activity. Although the genome-editing potential of thousands of other Cas9 orthologs remains largely untapped, it is not known how many will require similarly extensive engineering to achieve single-site accuracy within large (e.g. mammalian) genomes. In addition to its off-targeting propensity, SpyCas9 is encoded by a relatively ...


Small Rnas Gained During Epididymal Transit Of Sperm Are Essential For Embryonic Development In Mice, Colin C. Conine, Fengyun Sun, Lina Song, Jaime A. Rivera-Perez, Oliver J. Rando Apr 2018

Small Rnas Gained During Epididymal Transit Of Sperm Are Essential For Embryonic Development In Mice, Colin C. Conine, Fengyun Sun, Lina Song, Jaime A. Rivera-Perez, Oliver J. Rando

University of Massachusetts Medical School Faculty Publications

The small RNA payload of mammalian sperm undergoes dramatic remodeling during development, as several waves of microRNAs and tRNA fragments are shipped to sperm during post-testicular maturation in the epididymis. Here, we take advantage of this developmental process to probe the function of the sperm RNA payload in preimplantation development. We generated zygotes via intracytoplasmic sperm injection (ICSI) using sperm obtained from the proximal (caput) vs. distal (cauda) epididymis, then characterized development of the resulting embryos. Embryos generated using caput sperm significantly overexpress multiple regulatory factors throughout preimplantation development, and subsequently implant inefficiently and fail soon after implantation. Remarkably, microinjection ...


A Single Mechanism Of Biogenesis, Initiated And Directed By Piwi Proteins, Explains Pirna Production In Most Animals, Phillip D. Zamore, Ildar Gainetdinov, Cansu Colpan, Katharine Cecchini Apr 2018

A Single Mechanism Of Biogenesis, Initiated And Directed By Piwi Proteins, Explains Pirna Production In Most Animals, Phillip D. Zamore, Ildar Gainetdinov, Cansu Colpan, Katharine Cecchini

University of Massachusetts Medical School Faculty Publications

In animals, piRNAs guide PIWI-proteins to silence transposons and regulate gene expression. The mechanisms for making piRNAs have been proposed to differ among cell types, tissues, and animals. Our data instead suggest a single model that explains piRNA production in most animals. piRNAs initiate piRNA production by guiding PIWI proteins to slice precursor transcripts. Next, PIWI proteins direct the stepwise fragmentation of the sliced precursor transcripts, yielding tail-to-head strings of phased pre-piRNAs. Our analyses detect evidence for this piRNA biogenesis strategy across an evolutionarily broad range of animals including humans. Thus, PIWI proteins initiate and sustain piRNA biogenesis by the ...


Primate Immunodeficiency Virus Vpx And Vpr Counteract Transcriptional Repression Of Proviruses By The Hush Complex, Leonid Yurkovetskiy, Mehmet Hakan Guney, Kyusik Kim, Shih Lin Goh, Sean M. Mccauley, Ann Dauphin, William E. Diehl, Jeremy Luban Apr 2018

Primate Immunodeficiency Virus Vpx And Vpr Counteract Transcriptional Repression Of Proviruses By The Hush Complex, Leonid Yurkovetskiy, Mehmet Hakan Guney, Kyusik Kim, Shih Lin Goh, Sean M. Mccauley, Ann Dauphin, William E. Diehl, Jeremy Luban

University of Massachusetts Medical School Faculty Publications

Drugs that inhibit HIV-1 replication and prevent progression to AIDS do not eliminate HIV-1 proviruses from the chromosomes of long-lived CD4+ memory T cells. To escape eradication by these antiviral drugs, or by the host immune system, HIV-1 exploits poorly defined host factors that silence provirus transcription. These same factors, though, must be overcome by all retroviruses, including HIV-1 and other primate immunodeficiency viruses, in order to activate provirus transcription and produce new virus. Here we show that Vpx and Vpr, proteins from a wide range of primate immunodeficiency viruses, activate provirus transcription in human CD4+ T cells. Provirus activation ...


Higher-Order Organization Principles Of Pre-Translational Mrnps, Mihir Metkar, Hakan Ozadam, Bryan R. Lajoie, Maxim Imakaev, Leonid A. Mirny, Job Dekker, Melissa J. Moore Mar 2018

Higher-Order Organization Principles Of Pre-Translational Mrnps, Mihir Metkar, Hakan Ozadam, Bryan R. Lajoie, Maxim Imakaev, Leonid A. Mirny, Job Dekker, Melissa J. Moore

University of Massachusetts Medical School Faculty Publications

Compared to noncoding RNAs (ncRNAs) such as rRNAs and ribozymes, for which high resolution structures abound, little is known about the tertiary structures of mRNAs. In eukaryotic cells, newly made mRNAs are packaged with proteins in highly compacted mRNPs, but the manner of this mRNA compaction is unknown. Here we developed and implemented RIPPLiT (RNA ImmunoPrecipitation and Proximity Ligation in Tandem), a transcriptome-wide method for probing the 3D conformations of RNAs stably-associated with defined proteins, in this case exon junction complex (EJC) core factors. EJCs multimerize with other mRNP components to form megadalton sized complexes that protect large swaths of ...


Herpes Icp8 Protein Stimulates Homologous Recombination In Human Cells, Melvys Valledor, Richard S. Myers, Paul C. Schiller Feb 2018

Herpes Icp8 Protein Stimulates Homologous Recombination In Human Cells, Melvys Valledor, Richard S. Myers, Paul C. Schiller

University of Massachusetts Medical School Faculty Publications

Recombineering has transformed functional genomic analysis. Genome modification by recombineering using the phage lambda Red SynExo homologous recombination proteins Beta in Escherichia coli has approached 100% efficiency. While highly efficient in E. coli, recombineering using the Red SynExo in other organisms declines in efficiency roughly correlating with phylogenetic distance from E. coli. SynExo recombinases are common to double-stranded DNA viruses infecting a variety of organisms, including humans. Human Herpes virus Type 1 (HHV1) encodes a SynExo comprised of ICP8 synaptase and UL12 exonuclease. In a previous study, the Herpes SynExo was reconstituted in vitro and shown to catalyze a model ...


Regulation Of Atm And Atr By Smarcal1 And Brg1, Ramesh Sethy, Radhakrishnan Rakesh, Ketki Patne, Vijendra Arya, Tapan Sharma, Dominic T. Haokip, Reshma Kumari, Rohini Muthuswami Feb 2018

Regulation Of Atm And Atr By Smarcal1 And Brg1, Ramesh Sethy, Radhakrishnan Rakesh, Ketki Patne, Vijendra Arya, Tapan Sharma, Dominic T. Haokip, Reshma Kumari, Rohini Muthuswami

University of Massachusetts Medical School Faculty Publications

The G2/M checkpoint is activated on DNA damage by the ATM and ATR kinases that are regulated by post-translational modifications. In this paper, the transcriptional co-regulation of ATM and ATR by SMARCAL1 and BRG1, both members of the ATP-dependent chromatin remodeling protein family, is described. SMARCAL1 and BRG1 co-localize on the promoters of ATM and ATR; downregulation of SMARCAL1/BRG1 results in transcriptional repression of ATM/ATR and therefore, overriding of the G2/M checkpoint leading to mitotic abnormalities. On doxorubicin-induced DNA damage, SMARCAL1 and BRG1 are upregulated and in turn, upregulate the expression of ATM/ATR. Phosphorylation of ...


C-Berst: Defining Subnuclear Proteomic Landscapes At Genomic Elements With Dcas9-Apex2, Xin D. Gao, Li-Chun Tu, Aamir Mir, Tomas Rodriguez, Yue-He Ding, John D. Leszyk, Job Dekker, Scott A. Shaffer, Lihua Julie Zhu, Scot A. Wolfe, Erik J. Sontheimer Jan 2018

C-Berst: Defining Subnuclear Proteomic Landscapes At Genomic Elements With Dcas9-Apex2, Xin D. Gao, Li-Chun Tu, Aamir Mir, Tomas Rodriguez, Yue-He Ding, John D. Leszyk, Job Dekker, Scott A. Shaffer, Lihua Julie Zhu, Scot A. Wolfe, Erik J. Sontheimer

University of Massachusetts Medical School Faculty Publications

Mapping proteomic composition at distinct genomic loci and subnuclear landmarks in living cells has been a long-standing challenge. Here we report that dCas9-APEX2 Biotinylation at genomic Elements by Restricted Spatial Tagging (C-BERST) allows the rapid, unbiased mapping of proteomes near defined genomic loci, as demonstrated for telomeres and centromeres. By combining the spatially restricted enzymatic tagging enabled by APEX2 with programmable DNA targeting by dCas9, C-BERST has successfully identified nearly 50% of known telomere-associated factors and many known centromere-associated factors. We also identified and validated SLX4IP and RPA3 as telomeric factors, confirming C-BERST ...


A Synthetic Biology Approach To Probing Nucleosome Symmetry, Yuichi Ichikawa, Yuanyuan Chen, Vineeta Bajaj, Caitlin M. Connolly, Hsin-Jung Chou, Upasna Sharma, Hsiuyi V. Chen, Daniel N. Bolon, Oliver J. Rando, Paul D. Kaufman Sep 2017

A Synthetic Biology Approach To Probing Nucleosome Symmetry, Yuichi Ichikawa, Yuanyuan Chen, Vineeta Bajaj, Caitlin M. Connolly, Hsin-Jung Chou, Upasna Sharma, Hsiuyi V. Chen, Daniel N. Bolon, Oliver J. Rando, Paul D. Kaufman

University of Massachusetts Medical School Faculty Publications

The repeating subunit of chromatin, the nucleosome, includes two copies of each of the four core histones, and several recent studies have reported that asymmetrically modified nucleosomes occur at regulatory elements in vivo. To probe the mechanisms by which histone modifications are read out, we designed an obligate pair of H3 heterodimers, termed H3X and H3Y, which we validated genetically and biochemically. Comparing the effects of asymmetric histone tail point mutants with those of symmetric double mutants revealed that a single methylated H3K36 per nucleosome was sufficient to silence cryptic transcription in vivo. We also demonstrate the utility of this ...


Heterogeneity And Intrinsic Variation In Spatial Genome Organization, Elizabeth Finn, Gianluca Pegoraro, Hugo B. Brandao, Anne-Laure Valton, Marlies E. Oomen, Job Dekker, Leonid Mirny, Tom Misteli Aug 2017

Heterogeneity And Intrinsic Variation In Spatial Genome Organization, Elizabeth Finn, Gianluca Pegoraro, Hugo B. Brandao, Anne-Laure Valton, Marlies E. Oomen, Job Dekker, Leonid Mirny, Tom Misteli

University of Massachusetts Medical School Faculty Publications

The genome is hierarchically organized in 3D space and its architecture is altered in differentiation, development and disease. Some of the general principles that determine global 3D genome organization have been established. However, the extent and nature of cell-to-cell and cell-intrinsic variability in genome architecture are poorly characterized. Here, we systematically probe the heterogeneity in genome organization in human fibroblasts by combining high-resolution Hi-C datasets and high-throughput genome imaging. Optical mapping of several hundred genome interaction pairs at the single cell level demonstrates low steady-state frequencies of colocalization in the population and independent behavior of individual alleles in single nuclei ...


Ki-67 Contributes To Normal Cell Cycle Progression And Inactive X Heterochromatin In P21 Checkpoint-Proficient Human Cells, Xiaoming Sun, Aizhan Bizhanova, Timothy D. Matheson, Jun Yu, Lihua Julie Zhu, Paul D. Kaufman May 2017

Ki-67 Contributes To Normal Cell Cycle Progression And Inactive X Heterochromatin In P21 Checkpoint-Proficient Human Cells, Xiaoming Sun, Aizhan Bizhanova, Timothy D. Matheson, Jun Yu, Lihua Julie Zhu, Paul D. Kaufman

University of Massachusetts Medical School Faculty Publications

Ki-67 protein is widely used as a tumor proliferation marker. However, whether Ki-67 affects cell cycle progression has been controversial. Here, we demonstrate that depletion of Ki-67 in human hTERT-RPE1, WI-38, IMR90, hTERT-BJ cell lines and primary fibroblast cells slowed entry into S phase and coordinately downregulated genes related to DNA replication. Some gene expression changes were partially relieved in Ki-67-depleted hTERT-RPE1 cells by co-depletion of the Rb checkpoint protein, but more thorough suppression of the transcriptional and cell cycle defects was observed upon depletion of cell cycle inhibitor p21. Notably, induction of p21 upon depletion of Ki-67 was a ...


Prima: A Gene-Centered, Rna-To-Protein Method For Mapping Rna-Protein Interactions, Alex M. Tamburino, Ebru Kaymak, Shaleen Shrestha, Amy D. Holdorf, Sean P. Ryder, Albertha J. M. Walhout Sep 2016

Prima: A Gene-Centered, Rna-To-Protein Method For Mapping Rna-Protein Interactions, Alex M. Tamburino, Ebru Kaymak, Shaleen Shrestha, Amy D. Holdorf, Sean P. Ryder, Albertha J. M. Walhout

University of Massachusetts Medical School Faculty Publications

Interactions between RNA binding protein (RBP) and mRNAs are critical to post-transcriptional gene regulation. Eukaryotic genomes encode thousands of mRNAs and hundreds of RBPs. However, in contrast to interactions between transcription factors (TFs) and DNA, the interactome between RBPs and RNA has been explored for only a small number of proteins and RNAs. This is largely because the focus has been on using 'protein-centered' (RBP-to-RNA) interaction mapping methods that identify the RNAs with which an individual RBP interacts. While powerful, these methods cannot as of yet be applied to the entire RBPome. Moreover, it may be desirable for a researcher ...