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Articles 1 - 18 of 18

Full-Text Articles in Molecular Biology

Resistance From Afar: Distal Mutation V36m Allosterically Modulates The Active Site To Accentuate Drug Resistance In Hcv Ns3/4a Protease, Aysegul Ozen, Kuan-Hung Lin, Keith P. Romano, Davide Tavella, Alicia Newton, Christos J. Petropoulos, Wei Huang, Cihan Aydin, Celia A. Schiffer Dec 2018

Resistance From Afar: Distal Mutation V36m Allosterically Modulates The Active Site To Accentuate Drug Resistance In Hcv Ns3/4a Protease, Aysegul Ozen, Kuan-Hung Lin, Keith P. Romano, Davide Tavella, Alicia Newton, Christos J. Petropoulos, Wei Huang, Cihan Aydin, Celia A. Schiffer

University of Massachusetts Medical School Faculty Publications

Hepatitis C virus rapidly evolves, conferring resistance to direct acting antivirals. While resistance via active site mutations in the viral NS3/4A protease has been well characterized, the mechanism for resistance of non-active site mutations is unclear. R155K and V36M often co-evolve and while R155K alters the electrostatic network at the binding site, V36M is more than 13 Angstrom away. In this study the mechanism by which V36M confers resistance, in the context of R155K, is elucidated with drug susceptibility assays, crystal structures, and molecular dynamics (MD) simulations for three protease inhibitors: telaprevir, boceprevir and danoprevir. The R155K and R155K ...


Identification Of A Novel Invasion-Promoting Region In Insulin Receptor Substrate 2, Jose Mercado-Matos, Jenny Janusis, Sha Zhu, Samuel S. Chen, Leslie M. Shaw Jun 2018

Identification Of A Novel Invasion-Promoting Region In Insulin Receptor Substrate 2, Jose Mercado-Matos, Jenny Janusis, Sha Zhu, Samuel S. Chen, Leslie M. Shaw

University of Massachusetts Medical School Faculty Publications

Although the insulin receptor substrate (IRS) proteins IRS1 and IRS2 share considerable homology and activate common signaling pathways, their contributions to breast cancer are distinct. IRS1 has been implicated in the proliferation and survival of breast tumor cells. In contrast, IRS2 facilitates glycolysis, invasion, and metastasis. To determine the mechanistic basis for IRS2-dependent functions, we investigated unique structural features of IRS2 that are required for invasion. Our studies revealed that the ability of IRS2 to promote invasion is dependent upon upstream insulin-like growth factor 1 receptor (IGF-1R)/insulin receptor (IR) activation and the recruitment and activation of phosphatidylinositol 3-kinase (PI3K ...


All-In-One Adeno-Associated Virus Delivery And Genome Editing By Neisseria Meningitidis Cas9 In Vivo, Raed Ibraheim, Chun-Qing Song, Aamir Mir, Nadia Amrani, Wen Xue, Erik J. Sontheimer May 2018

All-In-One Adeno-Associated Virus Delivery And Genome Editing By Neisseria Meningitidis Cas9 In Vivo, Raed Ibraheim, Chun-Qing Song, Aamir Mir, Nadia Amrani, Wen Xue, Erik J. Sontheimer

University of Massachusetts Medical School Faculty Publications

Clustered, regularly interspaced, short palindromic repeats (CRISPR) and CRISPR-associated proteins (Cas) have recently opened a new avenue for gene therapy. Cas9 nuclease guided by a single-guide RNA (sgRNA) has been extensively used for genome editing. Currently, three Cas9 orthologs have been adapted forin vivo genome engineering applications: SpyCas9, SauCas9 and CjeCas9. However, additional in vivo editing platforms are needed, in part to enable a greater range of sequences to be accessed via viral vectors, especially those in which Cas9 and sgRNA are combined into a single vector genome. Here, we present an additional in vivo editing platform using Neisseria ...


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 ...


Jip1-Mediated Jnk Activation Negatively Regulates Synaptic Plasticity And Spatial Memory, Caroline Morel, Tessi Sherrin, Norman J. Kennedy, Kelly H. Forest, Seda Barutcu, Michael Robles, Ezekiel Carpenter-Hyland, Naghum Alfulaij, Claire L. Standen, Robert A. Nichols, Morris Benveniste, Roger J. Davis, Cedomir Todorovic Apr 2018

Jip1-Mediated Jnk Activation Negatively Regulates Synaptic Plasticity And Spatial Memory, Caroline Morel, Tessi Sherrin, Norman J. Kennedy, Kelly H. Forest, Seda Barutcu, Michael Robles, Ezekiel Carpenter-Hyland, Naghum Alfulaij, Claire L. Standen, Robert A. Nichols, Morris Benveniste, Roger J. Davis, Cedomir Todorovic

University of Massachusetts Medical School Faculty Publications

The c-Jun N-terminal kinase (JNK) signal transduction pathway is implicated in learning and memory. Here, we examined the role of JNK activation mediated by the JIP1 scaffold protein. We compared male wild-type mice with a mouse model harboring a point mutation in the Jip1 gene that selectively blocks JIP1-mediated JNK activation. These male mutant mice exhibited increased NMDA receptor currents, increased NMDA receptor-mediated gene expression, and a lower threshold for induction of hippocampal long-term potentiation. The JIP1 mutant mice also displayed improved hippocampus-dependent spatial memory and enhanced associative fear conditioning. These results were confirmed using a second JIP1 mutant mouse ...


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 ...


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 ...


The Trim-Nhl Protein Nhl-2 Is A Novel Co-Factor Of The Csr-1 And Hrde-1 22g-Rna Pathways, Peter R. Boag, Gregory M. Davis, Shikui Tu, Rhys N. Colson, Joshua W. T. Anderson, Menachem J. Gunzburg, Michelle A. Francisco, Debashish Ray, Tuhin Maity, Monica Z. Wu, Quaid D. Morris, Timothy R. Hughes, Jacqueline A. Wilce, University Of Toronto, Zhiping Weng Feb 2018

The Trim-Nhl Protein Nhl-2 Is A Novel Co-Factor Of The Csr-1 And Hrde-1 22g-Rna Pathways, Peter R. Boag, Gregory M. Davis, Shikui Tu, Rhys N. Colson, Joshua W. T. Anderson, Menachem J. Gunzburg, Michelle A. Francisco, Debashish Ray, Tuhin Maity, Monica Z. Wu, Quaid D. Morris, Timothy R. Hughes, Jacqueline A. Wilce, University Of Toronto, Zhiping Weng

University of Massachusetts Medical School Faculty Publications

Proper regulation of germline gene expression is essential for fertility and maintaining species integrity. In the C. elegans germline, a diverse repertoire of regulatory pathways promote the expression of endogenous germline genes and limit the expression of deleterious transcripts to maintain genome homeostasis. Here we show that the conserved TRIM-NHL protein, NHL-2, plays an essential role in the C. elegans germline, modulating germline chromatin and meiotic chromosome organization. We uncover a role for NHL-2 as a co-factor in both positively (CSR-1) and negatively (HRDE-1) acting germline 22G-small RNA pathways and the somatic nuclear RNAi pathway. Furthermore, we demonstrate that NHL-2 ...


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 ...


Pervasive Contingency And Entrenchment In A Billion Years Of Hsp90 Evolution, Tyler N. Starr, Julia Flynn, Parul Mishra, Daniel N. Bolon, Joseph W. Thornton Jan 2018

Pervasive Contingency And Entrenchment In A Billion Years Of Hsp90 Evolution, Tyler N. Starr, Julia Flynn, Parul Mishra, Daniel N. Bolon, Joseph W. Thornton

University of Massachusetts Medical School Faculty Publications

Interactions among mutations within a protein have the potential to make molecular evolution contingent and irreversible, but the extent to which epistasis actually shaped historical evolutionary trajectories is unclear. We addressed this question by identifying all amino acid substitutions that occurred during the billion-year evolutionary history of the heat shock protein 90 (Hsp90) ATPase domain beginning from a deep eukaryotic ancestor to modern Saccharomyces cerevisiae and then precisely measuring their fitness effects when introduced into both extant and reconstructed ancestral Hsp90 proteins. We find a pervasive influence of epistasis: of 98 derived states that evolved during history, most were deleterious ...


Loss Of The Cone-Enriched Caspase-7 Does Not Affect Secondary Cone Death In Retinitis Pigmentosa, Aditya Venkatesh, Shun-Yun Cheng, Claudio Punzo Dec 2017

Loss Of The Cone-Enriched Caspase-7 Does Not Affect Secondary Cone Death In Retinitis Pigmentosa, Aditya Venkatesh, Shun-Yun Cheng, Claudio Punzo

University of Massachusetts Medical School Faculty Publications

Purpose: The apoptotic mechanisms responsible for secondary cone death in retinitis pigmentosa (RP) remain largely unknown. The cone-enriched apoptotic protease caspase-7 (Casp7) is thought to be triggered by endoplasmic reticulum (ER) stress and plays a pivotal role in mice deficient in the cone cyclic nucleotide-gated channels, a deficiency that causes achromatopsia in humans and in mice with autosomal dominant rhodopsin mutations, in particular the T17M mutation. Thus, we tested in two mouse models of RP whether the cone-enriched Casp7 plays a role during secondary cone death.

Methods: Casp7 knockout mice were crossed to two different RP mouse models with significantly ...


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 ...


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 ...


Crystal Structure Of Apobec3a Bound To Single-Stranded Dna Reveals Structural Basis For Cytidine Deamination And Specificity, Takahide Kouno, Tania V. Silvas, Brendan J. Hilbert, Shivender Shandilya, Markus-Frederik Bohn, Brian A. Kelch, William E. Royer, Mohan Somasundaran, Nese Kurt Yilmaz, Hiroshi Matsuo, Celia A. Schiffer Apr 2017

Crystal Structure Of Apobec3a Bound To Single-Stranded Dna Reveals Structural Basis For Cytidine Deamination And Specificity, Takahide Kouno, Tania V. Silvas, Brendan J. Hilbert, Shivender Shandilya, Markus-Frederik Bohn, Brian A. Kelch, William E. Royer, Mohan Somasundaran, Nese Kurt Yilmaz, Hiroshi Matsuo, Celia A. Schiffer

University of Massachusetts Medical School Faculty Publications

Nucleic acid editing enzymes are essential components of the immune system that lethally mutate viral pathogens and somatically mutate immunoglobulins, and contribute to the diversification and lethality of cancers. Among these enzymes are the seven human APOBEC3 deoxycytidine deaminases, each with unique target sequence specificity and subcellular localization. While the enzymology and biological consequences have been extensively studied, the mechanism by which APOBEC3s recognize and edit DNA remains elusive. Here we present the crystal structure of a complex of a cytidine deaminase with ssDNA bound in the active site at 2.2 A. This structure not only visualizes the active ...


The 4d Nucleome Project, Job Dekker, Andrew S. Belmont, Mitchell Guttman, Victor O. Leshyk, John T. Lis, Stavros Lomvardas, Leonid A. Mirny, Clodagh C. O'Shea, Peter J. Park, Bing Ren, Joan C. Ritland Politz, Jay Shendure, Sheng Zong Jan 2017

The 4d Nucleome Project, Job Dekker, Andrew S. Belmont, Mitchell Guttman, Victor O. Leshyk, John T. Lis, Stavros Lomvardas, Leonid A. Mirny, Clodagh C. O'Shea, Peter J. Park, Bing Ren, Joan C. Ritland Politz, Jay Shendure, Sheng Zong

University of Massachusetts Medical School Faculty Publications

The spatial organization of the genome and its dynamics contribute to gene expression and cellular function in normal development as well as in disease. Although we are increasingly well equipped to determine a genome's sequence and linear chromatin composition, studying the three-dimensional organization of the genome with high spatial and temporal resolution remains challenging. The 4D Nucleome Network aims to develop and apply approaches to map the structure and dynamics of the human and mouse genomes in space and time with the long term goal of gaining deeper mechanistic understanding of how the nucleus is organized. The project will ...


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 ...


A Systematic Survey Of An Intragenic Epistatic Landscape, Claudia Bank, Ryan T. Hietpas, Jeffrey D. Jensen, Daniel N. Bolon Oct 2014

A Systematic Survey Of An Intragenic Epistatic Landscape, Claudia Bank, Ryan T. Hietpas, Jeffrey D. Jensen, Daniel N. Bolon

University of Massachusetts Medical School Faculty Publications

Mutations are the source of evolutionary variation. The interactions of multiple mutations can have important effects on fitness and evolutionary trajectories. We have recently described the distribution of fitness effects of all single mutations for a nine amino acid region of yeast Hsp90 (Hsp82) implicated in substrate binding. Here, we report and discuss the distribution of intragenic epistatic effects within this region in seven Hsp90 point mutant backgrounds of neutral to slightly deleterious effect, resulting in an analysis of more than 1000 double-mutants. We find negative epistasis between substitutions to be common, and positive epistasis to be rare – resulting in ...


The Cellular And Molecular Basis Of Bitter Tastant-Induced Bronchodilation, Cheng-Hai Zhang, Lawrence M. Lifshitz, Karl Uy, Mitsuo Ikebe, Kevin E. Fogarty, Ronghua Zhuge Mar 2013

The Cellular And Molecular Basis Of Bitter Tastant-Induced Bronchodilation, Cheng-Hai Zhang, Lawrence M. Lifshitz, Karl Uy, Mitsuo Ikebe, Kevin E. Fogarty, Ronghua Zhuge

University of Massachusetts Medical School Faculty Publications

Bronchodilators are a standard medicine for treating airway obstructive diseases, and beta2 adrenergic receptor agonists have been the most commonly used bronchodilators since their discovery. Strikingly, activation of G-protein-coupled bitter taste receptors (TAS2Rs) in airway smooth muscle (ASM) causes a stronger bronchodilation in vitro and in vivo than beta2 agonists, implying that new and better bronchodilators could be developed. A critical step towards realizing this potential is to understand the mechanisms underlying this bronchodilation, which remain ill-defined. An influential hypothesis argues that bitter tastants generate localized Ca(2+) signals, as revealed in cultured ASM cells, to activate large-conductance Ca(2 ...