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Medical Biochemistry

Thomas Jefferson University

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Articles 31 - 60 of 204

Full-Text Articles in Medicine and Health Sciences

Differential Recognition Of Canonical Nf-Κb Dimers By Importin Α3, Tyler J. Florio, Ravi K Lokareddy, Daniel P Yeggoni, Rajeshwer S Sankhala, Connor A Ott, Richard E Gillilan, Gino Cingolani Mar 2022

Differential Recognition Of Canonical Nf-Κb Dimers By Importin Α3, Tyler J. Florio, Ravi K Lokareddy, Daniel P Yeggoni, Rajeshwer S Sankhala, Connor A Ott, Richard E Gillilan, Gino Cingolani

Department of Biochemistry and Molecular Biology Faculty Papers

Nuclear translocation of the p50/p65 heterodimer is essential for NF-κB signaling. In unstimulated cells, p50/p65 is retained by the inhibitor IκBα in the cytoplasm that masks the p65-nuclear localization sequence (NLS). Upon activation, p50/p65 is translocated into the nucleus by the adapter importin α3 and the receptor importin β. Here, we describe a bipartite NLS in p50/p65, analogous to nucleoplasmin NLS but exposed in trans. Importin α3 accommodates the p50- and p65-NLSs at the major and minor NLS-binding pockets, respectively. The p50-NLS is the predominant binding determinant, while the p65-NLS induces a conformational change in the Armadillo 7 of importin …


Evidence For Paracrine Protective Role Of Exogenous Αa-Crystallin In Retinal Ganglion Cells, Madhu Nath, Zachary B Sluzala, Ashutosh S Phadte, Yang Shan, Angela M Myers, Patrice E Fort Mar 2022

Evidence For Paracrine Protective Role Of Exogenous Αa-Crystallin In Retinal Ganglion Cells, Madhu Nath, Zachary B Sluzala, Ashutosh S Phadte, Yang Shan, Angela M Myers, Patrice E Fort

Department of Biochemistry and Molecular Biology Faculty Papers

Expression and secretion of neurotrophic factors have long been known as a key mechanism of neuroglial interaction in the central nervous system. In addition, several other intrinsic neuroprotective pathways have been described, including those involving small heat shock proteins such as α-crystallins. While initially considered as a purely intracellular mechanism, both αA-crystallins and αB-crystallins have been recently reported to be secreted by glial cells. While an anti-apoptotic effect of such secreted αA-crystallin has been suggested, its regulation and protective potential remain unclear. We recently identified residue threonine 148 (T148) and its phosphorylation as a critical regulator of αA-crystallin intrinsic neuroprotective …


Viral Ejection Proteins: Mosaically Conserved, Conformational Gymnasts, Nicholas A. Swanson, Chun-Feng Hou, Gino Cingolani Feb 2022

Viral Ejection Proteins: Mosaically Conserved, Conformational Gymnasts, Nicholas A. Swanson, Chun-Feng Hou, Gino Cingolani

Department of Biochemistry and Molecular Biology Faculty Papers

Bacterial viruses (or bacteriophages) have developed formidable ways to deliver their genetic information inside bacteria, overcoming the complexity of the bacterial-cell envelope. In short-tailed phages of the Podoviridae superfamily, genome ejection is mediated by a set of mysterious internal virion proteins, also called ejection or pilot proteins, which are required for infectivity. The ejection proteins are challenging to study due to their plastic structures and transient assembly and have remained less characterized than classical components such as the phage coat protein or terminase subunit. However, a spate of recent cryo-EM structures has elucidated key features underscoring these proteins’ assembly and …


Positive Selection And Enhancer Evolution Shaped Lifespan And Body Mass In Great Apes, Daniela Tejada-Martinez, Roberto A Avelar, Inês Lopes, Bruce Zhang, Guy Novoa, João Pedro De Magalhães, Marco Trizzino Feb 2022

Positive Selection And Enhancer Evolution Shaped Lifespan And Body Mass In Great Apes, Daniela Tejada-Martinez, Roberto A Avelar, Inês Lopes, Bruce Zhang, Guy Novoa, João Pedro De Magalhães, Marco Trizzino

Department of Biochemistry and Molecular Biology Faculty Papers

Within primates, the great apes are outliers both in terms of body size and lifespan, since they include the largest and longest-lived species in the order. Yet, the molecular bases underlying such features are poorly understood. Here, we leveraged an integrated approach to investigate multiple sources of molecular variation across primates, focusing on over 10,000 genes, including approximately 1,500 previously associated with lifespan, and additional approximately 9,000 for which an association with longevity has never been suggested. We analyzed dN/dS rates, positive selection, gene expression (RNA-seq), and gene regulation (ChIP-seq). By analyzing the correlation between dN/dS, maximum lifespan, and body …


Liquid-Liquid Phase Separation Of Tdp-43 And Fus In Physiology And Pathology Of Neurodegenerative Diseases, Jenny L Carey, Lin Guo Feb 2022

Liquid-Liquid Phase Separation Of Tdp-43 And Fus In Physiology And Pathology Of Neurodegenerative Diseases, Jenny L Carey, Lin Guo

Department of Biochemistry and Molecular Biology Faculty Papers

Liquid-liquid phase separation of RNA-binding proteins mediates the formation of numerous membraneless organelles with essential cellular function. However, aberrant phase transition of these proteins leads to the formation of insoluble protein aggregates, which are pathological hallmarks of neurodegenerative diseases including ALS and FTD. TDP-43 and FUS are two such RNA-binding proteins that mislocalize and aggregate in patients of ALS and FTD. They have similar domain structures that provide multivalent interactions driving their phase separation in vitro and in the cellular environment. In this article, we review the factors that mediate and regulate phase separation of TDP-43 and FUS. We also …


Synthesis, Characterization And Physicochemical Properties Of Biogenic Silver Nanoparticle-Encapsulated Chitosan Bionanocomposites, Sreelekha Ediyilyam, Mahesh M Lalitha, Bini George, Sarojini Sharath Shankar, Stanisław Wacławek, Miroslav Černík, Vinod Vellora Thekkae Padil Jan 2022

Synthesis, Characterization And Physicochemical Properties Of Biogenic Silver Nanoparticle-Encapsulated Chitosan Bionanocomposites, Sreelekha Ediyilyam, Mahesh M Lalitha, Bini George, Sarojini Sharath Shankar, Stanisław Wacławek, Miroslav Černík, Vinod Vellora Thekkae Padil

Department of Medicine Faculty Papers

Green bionanocomposites have garnered considerable attention and applications in the pharmaceutical and packaging industries because of their intrinsic features, such as biocompatibility and biodegradability. The work presents a novel approach towards the combined effect of glycerol, tween 80 and silver nanoparticles (AgNPs) on the physicochemical properties of lyophilized chitosan (CH) scaffolds produced via a green synthesis method.The produced bionanocomposites were characterized with the help of Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The swelling behavior, water vapor transmission rate, moisture retention capability, degradation in Hanks solution, biodegradability in soil, mechanical strength and electrochemical performance of the composites …


Interplay Between An Atp-Binding Cassette F Protein And The Ribosome From Mycobacterium Tuberculosis, Zhicheng Cui, Xiaojun Li, Joonyoung Shin, Howard Gamper, Ya-Ming Hou, James C Sacchettini, Junjie Zhang Jan 2022

Interplay Between An Atp-Binding Cassette F Protein And The Ribosome From Mycobacterium Tuberculosis, Zhicheng Cui, Xiaojun Li, Joonyoung Shin, Howard Gamper, Ya-Ming Hou, James C Sacchettini, Junjie Zhang

Department of Biochemistry and Molecular Biology Faculty Papers

EttA, energy-dependent translational throttle A, is a ribosomal factor that gates ribosome entry into the translation elongation cycle. A detailed understanding of its mechanism of action is limited due to the lack of high-resolution structures along its ATPase cycle. Here we present the cryo-electron microscopy (cryo-EM) structures of EttA from Mycobacterium tuberculosis (Mtb), referred to as MtbEttA, in complex with the Mtb 70S ribosome initiation complex (70SIC) at the pre-hydrolysis (ADPNP) and transition (ADP-VO4) states, and the crystal structure of MtbEttA alone in the post-hydrolysis (ADP) state. We observe that MtbEttA binds the E-site of the Mtb 70SIC, remodeling the …


Characterization Of A New Whim Syndrome Mutant Reveals Mechanistic Differences In Regulation Of The Chemokine Receptor Cxcr4, Jiansong Luo, Francesco De Pascali, G Wendell Richmond, Amer M Khojah, Jeffrey L Benovic Dec 2021

Characterization Of A New Whim Syndrome Mutant Reveals Mechanistic Differences In Regulation Of The Chemokine Receptor Cxcr4, Jiansong Luo, Francesco De Pascali, G Wendell Richmond, Amer M Khojah, Jeffrey L Benovic

Department of Biochemistry and Molecular Biology Faculty Papers

WHIM syndrome is a rare immunodeficiency disorder that is characterized by warts, hypogammaglobulinemia, infections, and myelokathexis. While several gain-of-function mutations that lead to C-terminal truncations, frame shifts and point mutations in the chemokine receptor CXCR4 have been identified in WHIM syndrome patients, the functional effect of these mutations are not fully understood. Here, we report on a new WHIM syndrome mutation that results in a frame shift within the codon for Ser339 (S339fs5) and compare the properties of S339fs5 with wild-type CXCR4 and a previously identified WHIM syndrome mutant, R334X. The S339fs5 and R334X mutants exhibited significantly increased signaling compared …


Time-Resolved Cryo-Em Visualizes Ribosomal Translocation With Ef-G And Gtp, Christine E Carbone, Anna B Loveland, Howard Gamper, Ya-Ming Hou, Gabriel Demo, Andrei A Korostelev Dec 2021

Time-Resolved Cryo-Em Visualizes Ribosomal Translocation With Ef-G And Gtp, Christine E Carbone, Anna B Loveland, Howard Gamper, Ya-Ming Hou, Gabriel Demo, Andrei A Korostelev

Department of Biochemistry and Molecular Biology Faculty Papers

During translation, a conserved GTPase elongation factor-EF-G in bacteria or eEF2 in eukaryotes-translocates tRNA and mRNA through the ribosome. EF-G has been proposed to act as a flexible motor that propels tRNA and mRNA movement, as a rigid pawl that biases unidirectional translocation resulting from ribosome rearrangements, or by various combinations of motor- and pawl-like mechanisms. Using time-resolved cryo-EM, we visualized GTP-catalyzed translocation without inhibitors, capturing elusive structures of ribosome•EF-G intermediates at near-atomic resolution. Prior to translocation, EF-G binds near peptidyl-tRNA, while the rotated 30S subunit stabilizes the EF-G GTPase center. Reverse 30S rotation releases Pi and translocates peptidyl-tRNA and …


Targeting Oncogenic Gαq/11 In Uveal Melanoma, Dominic Lapadula, Jeffrey L Benovic Dec 2021

Targeting Oncogenic Gαq/11 In Uveal Melanoma, Dominic Lapadula, Jeffrey L Benovic

Department of Biochemistry and Molecular Biology Faculty Papers

Uveal melanoma is the most common intraocular cancer in adults and arises from the transformation of melanocytes in the uveal tract. While treatment of the primary tumor is often effective, 36–50% of patients develop metastatic disease primarily to the liver. While various strategies have been used to treat the metastatic disease, there remain no effective treatments that improve survival. Significant insight has been gained into the pathways that are altered in uveal melanoma, with mutually exclusive activating mutations in the GNAQ and GNA11 genes being found in over 90% of patients. These genes encode the alpha subunits of the hetetrotrimeric …


Tera-Seq: True End-To-End Sequencing Of Native Rna Molecules For Transcriptome Characterization, Fadia Ibrahim, Jan Oppelt, Manolis Maragkakis, Zissimos Mourelatos Nov 2021

Tera-Seq: True End-To-End Sequencing Of Native Rna Molecules For Transcriptome Characterization, Fadia Ibrahim, Jan Oppelt, Manolis Maragkakis, Zissimos Mourelatos

Department of Biochemistry and Molecular Biology Faculty Papers

Direct sequencing of single, native RNA molecules through nanopores has a strong potential to transform research in all aspects of RNA biology and clinical diagnostics. The existing platform from Oxford Nanopore Technologies is unable to sequence the very 5′ ends of RNAs and is limited to polyadenylated molecules. Here, we develop True End-to-end RNA Sequencing (TERA-Seq), a platform that addresses these limitations, permitting more thorough transcriptome characterization. TERA-Seq describes both poly-and non-polyadenylated RNA molecules and accurately identifies their native 5′ and 3′ ends by ligating uniquely designed adapters that are sequenced along with the transcript. We find that capped, full-length …


Expression And Purification Of Phage T7 Ejection Proteins For Cryo-Em Analysis, Nicholas A. Swanson, Ravi K Lokareddy, Fenglin Li, Chun-Feng Hou, Mikhail Pavlenok, Michael Niederweis, Gino Cingolani Nov 2021

Expression And Purification Of Phage T7 Ejection Proteins For Cryo-Em Analysis, Nicholas A. Swanson, Ravi K Lokareddy, Fenglin Li, Chun-Feng Hou, Mikhail Pavlenok, Michael Niederweis, Gino Cingolani

Department of Biochemistry and Molecular Biology Faculty Papers

Bacteriophages of the Podoviridae family densely package their genomes into precursor capsids alongside internal virion proteins called ejection proteins. In phage T7 these proteins (gp14, gp15, and gp16) are ejected into the host envelope forming a DNA-ejectosome for genome delivery. Here, we describe the purification and characterization of recombinant gp14, gp15, and gp16. This protocol was used for high-resolution cryo-EM structure analysis of the T7 periplasmic tunnel and can be adapted to study ejection proteins from other phages. For complete details on the use and execution of this protocol, please refer to Swanson et al.


Inability To Switch From Arid1a-Baf To Arid1b-Baf Impairs Exit From Pluripotency And Commitment Towards Neural Crest Formation In Arid1b-Related Neurodevelopmental Disorders, Luca Pagliaroli, Patrizia Porazzi, Alyxandra T Curtis, Chiara Scopa, Harald M M Mikkers, Christian Freund, Lucia Daxinger, Sandra Deliard, Sarah A Welsh, Sarah Offley, Connor A Ott, Bruno Calabretta, Samantha A Brugmann, Gijs W E Santen, Marco Trizzino Nov 2021

Inability To Switch From Arid1a-Baf To Arid1b-Baf Impairs Exit From Pluripotency And Commitment Towards Neural Crest Formation In Arid1b-Related Neurodevelopmental Disorders, Luca Pagliaroli, Patrizia Porazzi, Alyxandra T Curtis, Chiara Scopa, Harald M M Mikkers, Christian Freund, Lucia Daxinger, Sandra Deliard, Sarah A Welsh, Sarah Offley, Connor A Ott, Bruno Calabretta, Samantha A Brugmann, Gijs W E Santen, Marco Trizzino

Department of Biochemistry and Molecular Biology Faculty Papers

Subunit switches in the BAF chromatin remodeler are essential during development. ARID1B and its paralog ARID1A encode for mutually exclusive BAF subunits. De novo ARID1B haploinsufficient mutations cause neurodevelopmental disorders, including Coffin-Siris syndrome, which is characterized by neurological and craniofacial features. Here, we leveraged ARID1B+/- Coffin-Siris patient-derived iPSCs and modeled cranial neural crest cell (CNCC) formation. We discovered that ARID1B is active only during the first stage of this process, coinciding with neuroectoderm specification, where it is part of a lineage-specific BAF configuration (ARID1B-BAF). ARID1B-BAF regulates exit from pluripotency and lineage commitment by attenuating thousands of enhancers and genes of …


Targeting The Cdk6 Dependence Of Ph+ Acute Lymphoblastic Leukemia, Patrizia Porazzi, Marco De Dominici, Joseph Salvino, Bruno Calabretta Sep 2021

Targeting The Cdk6 Dependence Of Ph+ Acute Lymphoblastic Leukemia, Patrizia Porazzi, Marco De Dominici, Joseph Salvino, Bruno Calabretta

Department of Cancer Biology Faculty Papers

Ph+ ALL is a poor-prognosis leukemia subtype driven by the BCR-ABL1 oncogene, either the p190-or the p210-BCR/ABL isoform in a 70:30 ratio. Tyrosine Kinase inhibitors (TKIs) are the drugs of choice in the therapy of Ph+ ALL. In combination with standard chemotherapy, TKIs have markedly improved the outcome of Ph+ ALL, in particular if this treatment is followed by bone marrow transplantation. However, resistance to TKIs develops with high frequency, causing leukemia relapse that results in


The Penn State Protein Ladder System For Inexpensive Protein Molecular Weight Markers, Ryan T Santilli, John E Williamson, Yoshitaka Shibata, Rosalie P Sowers, Andrew N. Fleischman, Song Tan Aug 2021

The Penn State Protein Ladder System For Inexpensive Protein Molecular Weight Markers, Ryan T Santilli, John E Williamson, Yoshitaka Shibata, Rosalie P Sowers, Andrew N. Fleischman, Song Tan

Department of Anesthesiology Faculty Papers

We have created the Penn State Protein Ladder system to produce protein molecular weight markers easily and inexpensively (less than a penny a lane). The system includes plasmids which express 10, 15, 20, 30, 40, 50, 60, 80 and 100 kD proteins in E. coli. Each protein migrates appropriately on SDS-PAGE gels, is expressed at very high levels (10–50 mg per liter of culture), is easy to purify via histidine tags and can be detected directly on Western blots via engineered immunoglobulin binding domains. We have also constructed plasmids to express 150 and 250 kD proteins. For more efficient production, …


Structural Basis For +1 Ribosomal Frameshifting During Ef-G-Catalyzed Translocation., Gabriel Demo, Howard Gamper, Anna B. Loveland, Isao Masuda, Christine E. Carbone, Egor Svidritskiy, Ya-Ming Hou, Andrei A. Korostelev Jul 2021

Structural Basis For +1 Ribosomal Frameshifting During Ef-G-Catalyzed Translocation., Gabriel Demo, Howard Gamper, Anna B. Loveland, Isao Masuda, Christine E. Carbone, Egor Svidritskiy, Ya-Ming Hou, Andrei A. Korostelev

Department of Biochemistry and Molecular Biology Faculty Papers

Frameshifting of mRNA during translation provides a strategy to expand the coding repertoire of cells and viruses. How and where in the elongation cycle +1-frameshifting occurs remains poorly understood. We describe seven ~3.5-Å-resolution cryo-EM structures of 70S ribosome complexes, allowing visualization of elongation and translocation by the GTPase elongation factor G (EF-G). Four structures with a + 1-frameshifting-prone mRNA reveal that frameshifting takes place during translocation of tRNA and mRNA. Prior to EF-G binding, the pre-translocation complex features an in-frame tRNA-mRNA pairing in the A site. In the partially translocated structure with EF-G•GDPCP, the tRNA shifts to the +1-frame near …


Chloride Sensing By Wnk1 Regulates Nlrp3 Inflammasome Activation And Pyroptosis., Lindsey Mayes-Hopfinger, Aura Enache, Jian Xie, Chou-Long Huang, Robert Köchl, Victor L.J. Tybulewicz, Teresa Fernandes-Alnemri, Emad S. Alnemri Jul 2021

Chloride Sensing By Wnk1 Regulates Nlrp3 Inflammasome Activation And Pyroptosis., Lindsey Mayes-Hopfinger, Aura Enache, Jian Xie, Chou-Long Huang, Robert Köchl, Victor L.J. Tybulewicz, Teresa Fernandes-Alnemri, Emad S. Alnemri

Department of Biochemistry and Molecular Biology Faculty Papers

The NLRP3 inflammasome mediates the production of proinflammatory cytokines and initiates inflammatory cell death. Although NLRP3 is essential for innate immunity, aberrant NLRP3 inflammasome activation contributes to a wide variety of inflammatory diseases. Understanding the pathways that control NLRP3 activation will help develop strategies to treat these diseases. Here we identify WNK1 as a negative regulator of the NLRP3 inflammasome. Macrophages deficient in WNK1 protein or kinase activity have increased NLRP3 activation and pyroptosis compared with control macrophages. Mice with conditional knockout of WNK1 in macrophages have increased IL-1β production in response to NLRP3 stimulation compared with control mice. Mechanistically, …


Dna Polymerase Θ: A Cancer Drug Target With Reverse Transcriptase Activity, Xiaojiang Chen, Richard T. Pomerantz Jul 2021

Dna Polymerase Θ: A Cancer Drug Target With Reverse Transcriptase Activity, Xiaojiang Chen, Richard T. Pomerantz

Department of Biochemistry and Molecular Biology Faculty Papers

The emergence of precision medicine from the development of Poly (ADP‐ribose) polymerase (PARP) inhibitors that preferentially kill cells defective in homologous recombination has sparked wide interest in identifying and characterizing additional DNA repair enzymes that are synthetic lethal with HR factors. DNA polymerase theta (Polθ) is a validated anti‐cancer drug target that is synthetic lethal with HR factors and other DNA repair proteins and confers cellular resistance to various genotoxic cancer therapies. Since its initial characterization as a helicase‐polymerase fusion protein in 2003, many exciting and unexpected activities of Polθ in microhomology‐mediated end‐joining (MMEJ) and translesion synthesis (TLS) have been …


Characterization Of Hnrnpa1 Mutations Defines Diversity In Pathogenic Mechanisms And Clinical Presentation., Danique Beijer, Hong Joo Kim, Lin Guo, Kevin O'Donovan, Inès Mademan, Tine Deconinck, Kristof Van Schil, Charlotte M Fare, Lauren E Drake, Alice F Ford, Andrzej Kochański, Dagmara Kabzińska, Nicolas Dubuisson, Peter Van Den Bergh, Nicol C Voermans, Richard Jlf Lemmers, Silvère M Van Der Maarel, Devon Bonner, Jacinda B Sampson, Matthew T Wheeler, Anahit Mehrabyan, Steven Palmer, Peter De Jonghe, James Shorter, J Paul Taylor, Jonathan Baets Jul 2021

Characterization Of Hnrnpa1 Mutations Defines Diversity In Pathogenic Mechanisms And Clinical Presentation., Danique Beijer, Hong Joo Kim, Lin Guo, Kevin O'Donovan, Inès Mademan, Tine Deconinck, Kristof Van Schil, Charlotte M Fare, Lauren E Drake, Alice F Ford, Andrzej Kochański, Dagmara Kabzińska, Nicolas Dubuisson, Peter Van Den Bergh, Nicol C Voermans, Richard Jlf Lemmers, Silvère M Van Der Maarel, Devon Bonner, Jacinda B Sampson, Matthew T Wheeler, Anahit Mehrabyan, Steven Palmer, Peter De Jonghe, James Shorter, J Paul Taylor, Jonathan Baets

Department of Biochemistry and Molecular Biology Faculty Papers

Mutations in HNRNPA1 encoding heterogeneous nuclear ribonucleoprotein (hnRNP) A1 are a rare cause of amyotrophic lateral sclerosis (ALS) and multisystem proteinopathy (MSP). hnRNPA1 is part of the group of RNA-binding proteins (RBPs) that assemble with RNA to form RNPs. hnRNPs are concentrated in the nucleus and function in pre-mRNA splicing, mRNA stability, and the regulation of transcription and translation. During stress, hnRNPs, mRNA, and other RBPs condense in the cytoplasm to form stress granules (SGs). SGs are implicated in the pathogenesis of (neuro-)degenerative diseases, including ALS and inclusion body myopathy (IBM). Mutations in RBPs that affect SG biology, including FUS, …


Analysis Of The Dna-Binding Properties Of Alx1, An Evolutionarily Conserved Regulator Of Skeletogenesis In Echinoderms, Jennifer Guerrero-Santoro, Jian Ming Khor, Ayşe Haruka Açıkbaş, James B. Jaynes, Charles A Ettensohn Jul 2021

Analysis Of The Dna-Binding Properties Of Alx1, An Evolutionarily Conserved Regulator Of Skeletogenesis In Echinoderms, Jennifer Guerrero-Santoro, Jian Ming Khor, Ayşe Haruka Açıkbaş, James B. Jaynes, Charles A Ettensohn

Department of Biochemistry and Molecular Biology Faculty Papers

Alx1, a homeodomain-containing transcription factor, is a highly conserved regulator of skeletogenesis in echinoderms. In sea urchins, Alx1 plays a central role in the differentiation of embryonic primary mesenchyme cells (PMCs) and positively regulates the transcription of most biomineralization genes expressed by these cells. The alx1 gene arose via duplication and acquired a skeletogenic function distinct from its paralog (alx4) through the exonization of a 41-amino acid motif (the D2 domain). Alx1 and Alx4 contain glutamine-50 paired-type homeodomains, which interact preferentially with palindromic binding sites in vitro. Chromatin immunoprecipitation sequencing (ChIP-seq) studies have shown, however, that Alx1 binds both to …


An Insulator Blocks Access To Enhancers By An Illegitimate Promoter, Preventing Repression By Transcriptional Interference., Miki Fujioka, Anastasiya Nezdyur, James B. Jaynes Apr 2021

An Insulator Blocks Access To Enhancers By An Illegitimate Promoter, Preventing Repression By Transcriptional Interference., Miki Fujioka, Anastasiya Nezdyur, James B. Jaynes

Department of Biochemistry and Molecular Biology Faculty Papers

Several distinct activities and functions have been described for chromatin insulators, which separate genes along chromosomes into functional units. Here, we describe a novel mechanism of functional separation whereby an insulator prevents gene repression. When the homie insulator is deleted from the end of a Drosophila even skipped (eve) locus, a flanking P-element promoter is activated in a partial eve pattern, causing expression driven by enhancers in the 3' region to be repressed. The mechanism involves transcriptional read-through from the flanking promoter. This conclusion is based on the following. Read-through driven by a heterologous enhancer is sufficient to repress, even …


A Stress-Free Strategy To Correct Point Mutations In Patient Ips Cells, Jingli Cai, Elizabeth Kropf, Ya-Ming Hou, Lorraine Iacovitti Apr 2021

A Stress-Free Strategy To Correct Point Mutations In Patient Ips Cells, Jingli Cai, Elizabeth Kropf, Ya-Ming Hou, Lorraine Iacovitti

Department of Biochemistry and Molecular Biology Faculty Papers

When studying patient specific induced pluripotent stem cells (iPS cells) as a disease model, the ideal control is an isogenic line that has corrected the point mutation, instead of iPS cells from siblings or other healthy subjects. However, repairing a point mutation in iPS cells even with the newly developed CRISPR-Cas9 technique remains difficult and time-consuming. Here we report a strategy that makes the Cas9 “knock-in” methodology both hassle-free and error-free. Instead of selecting a Cas9 recognition site close to the point mutation, we chose a site located in the nearest intron. We constructed a donor template with the fragment …


Polθ Promotes The Repair Of 5'-Dna-Protein Crosslinks By Microhomology-Mediated End-Joining, Gurushankar Chandramouly, Shuren Liao, Timur Rusanov, Nikita Borisonnik, Marissa L Calbert, Tatiana Kent, Katherine Sullivan-Reed, Umeshkumar Vekariya, Ekaterina Kashkina, Tomasz Skorski, Hong Yan, Richard T Pomerantz Mar 2021

Polθ Promotes The Repair Of 5'-Dna-Protein Crosslinks By Microhomology-Mediated End-Joining, Gurushankar Chandramouly, Shuren Liao, Timur Rusanov, Nikita Borisonnik, Marissa L Calbert, Tatiana Kent, Katherine Sullivan-Reed, Umeshkumar Vekariya, Ekaterina Kashkina, Tomasz Skorski, Hong Yan, Richard T Pomerantz

Department of Biochemistry and Molecular Biology Faculty Papers

DNA polymerase θ (Polθ) confers resistance to chemotherapy agents that cause DNA-protein crosslinks (DPCs) at double-strand breaks (DSBs), such as topoisomerase inhibitors. This suggests Polθ might facilitate DPC repair by microhomology-mediated end-joining (MMEJ). Here, we investigate Polθ repair of DSBs carrying DPCs by monitoring MMEJ in Xenopus egg extracts. MMEJ in extracts is dependent on Polθ, exhibits the MMEJ repair signature, and efficiently repairs 5' terminal DPCs independently of non-homologous end-joining and the replisome. We demonstrate that Polθ promotes the repair of 5' terminal DPCs in mammalian cells by using an MMEJ reporter and find that Polθ confers resistance to …


The Evolutionary Conserved Swi/Snf Subunits Arid1a And Arid1b Are Key Modulators Of Pluripotency And Cell-Fate Determination, Luca Pagliaroli, Marco Trizzino Mar 2021

The Evolutionary Conserved Swi/Snf Subunits Arid1a And Arid1b Are Key Modulators Of Pluripotency And Cell-Fate Determination, Luca Pagliaroli, Marco Trizzino

Department of Biochemistry and Molecular Biology Faculty Papers

Organismal development is a process that requires a fine-tuned control of cell fate and identity, through timely regulation of lineage-specific genes. These processes are mediated by the concerted action of transcription factors and protein complexes that orchestrate the interaction between cis-regulatory elements (enhancers, promoters) and RNA Polymerase II to elicit transcription. A proper understanding of these dynamics is essential to elucidate the mechanisms underlying developmental diseases. Many developmental disorders, such as Coffin-Siris Syndrome, characterized by growth impairment and intellectual disability are associated with mutations in subunits of the SWI/SNF chromatin remodeler complex, which is an essential regulator of transcription. ARID1B …


Three-Dimensional Structure Of Human Cyclooxygenase (Hcox)-1., Morena Miciaccia, Benny Danilo Belviso, Mariaclara Iaselli, Gino Cingolani, Savina Ferorelli, Marianna Cappellari, Paola Loguercio Polosa, Maria Grazia Perrone, Rocco Caliandro, Antonio Scilimati Feb 2021

Three-Dimensional Structure Of Human Cyclooxygenase (Hcox)-1., Morena Miciaccia, Benny Danilo Belviso, Mariaclara Iaselli, Gino Cingolani, Savina Ferorelli, Marianna Cappellari, Paola Loguercio Polosa, Maria Grazia Perrone, Rocco Caliandro, Antonio Scilimati

Department of Biochemistry and Molecular Biology Faculty Papers

The beneficial effects of Cyclooxygenases (COX) inhibitors on human health have been known for thousands of years. Nevertheless, COXs, particularly COX-1, have been linked to a plethora of human diseases such as cancer, heart failure, neurological and neurodegenerative diseases only recently. COXs catalyze the first step in the biosynthesis of prostaglandins (PGs) and are among the most important mediators of inflammation. All published structural work on COX-1 deals with the ovine isoenzyme, which is easier to produce in milligram-quantities than the human enzyme and crystallizes readily. Here, we report the long-sought structure of the human cyclooxygenase-1 (hCOX-1) that we refined …


Dna Mismatch Repair And Its Role In Huntington's Disease, Ravi R Iyer, Anna Pluciennik Feb 2021

Dna Mismatch Repair And Its Role In Huntington's Disease, Ravi R Iyer, Anna Pluciennik

Department of Biochemistry and Molecular Biology Faculty Papers

DNA mismatch repair (MMR) is a highly conserved genome stabilizing pathway that corrects DNA replication errors, limits chromosomal rearrangements, and mediates the cellular response to many types of DNA damage. Counterintuitively, MMR is also involved in the generation of mutations, as evidenced by its role in causing somatic triplet repeat expansion in Huntington's disease (HD) and other neurodegenerative disorders. In this review, we discuss the current state of mechanistic knowledge of MMR and review the roles of key enzymes in this pathway. We also present the evidence for mutagenic function of MMR in CAG repeat expansion and consider mechanistic hypotheses …


Distinct Mechanisms Control Genome Recognition By P53 At Its Target Genes Linked To Different Cell Fates., Marina Farkas, Hideharu Hashimoto, Yingtao Bi, Ramana V Davuluri, Lois Resnick-Silverman, James J. Manfredi, Erik W. Debler, Steven B. Mcmahon Jan 2021

Distinct Mechanisms Control Genome Recognition By P53 At Its Target Genes Linked To Different Cell Fates., Marina Farkas, Hideharu Hashimoto, Yingtao Bi, Ramana V Davuluri, Lois Resnick-Silverman, James J. Manfredi, Erik W. Debler, Steven B. Mcmahon

Department of Biochemistry and Molecular Biology Faculty Papers

The tumor suppressor p53 integrates stress response pathways by selectively engaging one of several potential transcriptomes, thereby triggering cell fate decisions (e.g., cell cycle arrest, apoptosis). Foundational to this process is the binding of tetrameric p53 to 20-bp response elements (REs) in the genome (RRRCWWGYYYN0-13RRRCWWGYYY). In general, REs at cell cycle arrest targets (e.g. p21) are of higher affinity than those at apoptosis targets (e.g., BAX). However, the RE sequence code underlying selectivity remains undeciphered. Here, we identify molecular mechanisms mediating p53 binding to high- and low-affinity REs by showing that key determinants of the code are embedded …


Insights Into Genome Recoding From The Mechanism Of A Classic +1-Frameshifting Trna., Howard Gamper, Haixing Li, Isao Masuda, D. Miklos Robkis, Thomas Christian, Adam B. Conn, Gregor Blaha, E. James Petersson, Ruben L. Gonzalez, Ya-Ming Hou Jan 2021

Insights Into Genome Recoding From The Mechanism Of A Classic +1-Frameshifting Trna., Howard Gamper, Haixing Li, Isao Masuda, D. Miklos Robkis, Thomas Christian, Adam B. Conn, Gregor Blaha, E. James Petersson, Ruben L. Gonzalez, Ya-Ming Hou

Department of Biochemistry and Molecular Biology Faculty Papers

While genome recoding using quadruplet codons to incorporate non-proteinogenic amino acids is attractive for biotechnology and bioengineering purposes, the mechanism through which such codons are translated is poorly understood. Here we investigate translation of quadruplet codons by a +1-frameshifting tRNA, SufB2, that contains an extra nucleotide in its anticodon loop. Natural post-transcriptional modification of SufB2 in cells prevents it from frameshifting using a quadruplet-pairing mechanism such that it preferentially employs a triplet-slippage mechanism. We show that SufB2 uses triplet anticodon-codon pairing in the 0-frame to initially decode the quadruplet codon, but subsequently shifts to the +1-frame during tRNA-mRNA translocation. SufB2 …


Myc Regulates Ribosome Biogenesis And Mitochondrial Gene Expression Programs Through Its Interaction With Host Cell Factor-1., Tessa M. Popay, Jing Wang, Clare M. Adams, Gregory Caleb Howard, Simona G. Codreanu, Stacy D. Sherrod, John A. Mclean, Lance R. Thomas, Shelly L. Lorey, Yuichi J. Machida, April M. Weissmiller, Christine M. Eischen, Qi Liu, William P. Tansey Jan 2021

Myc Regulates Ribosome Biogenesis And Mitochondrial Gene Expression Programs Through Its Interaction With Host Cell Factor-1., Tessa M. Popay, Jing Wang, Clare M. Adams, Gregory Caleb Howard, Simona G. Codreanu, Stacy D. Sherrod, John A. Mclean, Lance R. Thomas, Shelly L. Lorey, Yuichi J. Machida, April M. Weissmiller, Christine M. Eischen, Qi Liu, William P. Tansey

Department of Cancer Biology Faculty Papers

The oncoprotein transcription factor MYC is a major driver of malignancy and a highly validated but challenging target for the development of anticancer therapies. Novel strategies to inhibit MYC may come from understanding the co-factors it uses to drive pro-tumorigenic gene expression programs, providing their role in MYC activity is understood. Here we interrogate how one MYC co-factor, host cell factor (HCF)-1, contributes to MYC activity in a human Burkitt lymphoma setting. We identify genes connected to mitochondrial function and ribosome biogenesis as direct MYC/HCF-1 targets and demonstrate how modulation of the MYC-HCF-1 interaction influences cell growth, metabolite profiles, global …


Purification And Use Of Trna For Enzymatic Post-Translational Addition Of Amino Acids To Proteins., Irem Avcilar-Kucukgoze, Howard Gamper, Ya-Ming Hou, Anna Kashina Dec 2020

Purification And Use Of Trna For Enzymatic Post-Translational Addition Of Amino Acids To Proteins., Irem Avcilar-Kucukgoze, Howard Gamper, Ya-Ming Hou, Anna Kashina

Department of Biochemistry and Molecular Biology Faculty Papers

Post-translational addition of amino acids to proteins by enzymes using aminoacyl-tRNA is an emerging regulatory mechanism. Examples include Arg transfer in eukaryotes, Leu/Phe transfer in bacteria, and tRNA-synthetase-mediated addition of amino acids to Lys side chains. Here, we present a method of purification and use of tRNA for such reactions, focusing on tRNAArg and its use for arginylation. This method can also be used for other tRNA-mediated reactions. For complete details on the use and execution of this protocol, please refer to Avcilar-Kucukgoze et al. (2020).