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Full-Text Articles in Medical Cell Biology

A Conserved Mechanism For Hormesis In Molecular Systems, Sharon N. Greenwood, Regina G. Belz, Brian P. Weiser Jul 2022

A Conserved Mechanism For Hormesis In Molecular Systems, Sharon N. Greenwood, Regina G. Belz, Brian P. Weiser

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Hormesis refers to dose-response phenomena where low dose treatments elicit a response that is opposite the response observed at higher doses. Hormetic dose-response relationships have been observed throughout all of biology, but the underlying determinants of many reported hormetic dose-responses have not been identified. In this report, we describe a conserved mechanism for hormesis on the molecular level where low dose treatments enhance a response that becomes reduced at higher doses. The hormetic mechanism relies on the ability of protein homo-multimers to simultaneously interact with a substrate and a competitor on different subunits at low doses of competitor. In this …


Evidence That Brain-Reactive Autoantibodies Contribute To Chronic Neuronal Internalization Of Exogenous Amyloid-Β1-42 And Key Cell Surface Proteins During Alzheimer's Disease Pathogenesis, Eric L Goldwaser, Nimish K Acharya, Hao Wu, George A Godsey, Abhirup Sarkar, Cassandra A Demarshall, Mary C Kosciuk, Robert G Nagele Mar 2020

Evidence That Brain-Reactive Autoantibodies Contribute To Chronic Neuronal Internalization Of Exogenous Amyloid-Β1-42 And Key Cell Surface Proteins During Alzheimer's Disease Pathogenesis, Eric L Goldwaser, Nimish K Acharya, Hao Wu, George A Godsey, Abhirup Sarkar, Cassandra A Demarshall, Mary C Kosciuk, Robert G Nagele

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Blood-brain barrier (BBB) permeability is a recognized early feature of Alzheimer's disease (AD). In the present study, we examined consequences of increased BBB permeability on the development of AD-related pathology by tracking selected leaked plasma components and their interactions with neurons in vivo and in vitro. Histological sections of cortical regions of postmortem AD brains were immunostained to determine the distribution of amyloid-β1-42 (Aβ42), cathepsin D, IgG, GluR2/3, and alpha7 nicotinic acetylcholine receptor (α7nAChR). Results revealed that chronic IgG binding to pyramidal neurons coincided with internalization of Aβ42, IgG, GluR2/3, and α7nAChR as well as lysosomal compartment expansion in these …


Cyclin C Regulated Oxidative Stress Responsive Transcriptome In Mus Musculus Embryonic Fibroblasts, David C Stieg, Kai-Ti Chang, Katrina F Cooper, Randy Strich Jun 2019

Cyclin C Regulated Oxidative Stress Responsive Transcriptome In Mus Musculus Embryonic Fibroblasts, David C Stieg, Kai-Ti Chang, Katrina F Cooper, Randy Strich

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

The transcriptional changes that occur in response to oxidative stress help direct the decision to maintain cell viability or enter a cell death pathway. Cyclin C-Cdk8 is a conserved kinase that associates with the RNA polymerase II Mediator complex that stimulates or represses transcription depending on the locus. In response to oxidative stress, cyclin C, but not Cdk8, displays partial translocation into the cytoplasm. These findings open the possibility that cyclin C relocalization is a regulatory mechanism governing oxidative stress-induced transcriptional changes. In the present study, the cyclin C-dependent transcriptome was determined and compared to transcriptional changes occurring in oxidatively …


Yeast Mitochondrial Protein Pet111p Binds Directly To Two Distinct Targets In Cox2 Mrna, Suggesting A Mechanism Of Translational Activation, Julia L Jones, Katharina B Hofmann, Andrew T Cowan, Dmitry Temiakov, Patrick Cramer, Michael Anikin May 2019

Yeast Mitochondrial Protein Pet111p Binds Directly To Two Distinct Targets In Cox2 Mrna, Suggesting A Mechanism Of Translational Activation, Julia L Jones, Katharina B Hofmann, Andrew T Cowan, Dmitry Temiakov, Patrick Cramer, Michael Anikin

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

The genes in mitochondrial DNA code for essential subunits of the respiratory chain complexes. In yeast, expression of mitochondrial genes is controlled by a group of gene-specific translational activators encoded in the nucleus. These factors appear to be part of a regulatory system that enables concerted expression of the necessary genes from both nuclear and mitochondrial genomes to produce functional respiratory complexes. Many of the translational activators are believed to act on the 5'-untranslated regions of target mRNAs, but the molecular mechanisms involved in this regulation remain obscure. In this study, we used a combination of in vivo and in …


Cysteine Residues Contribute To The Dimerization And Enzymatic Activity Of Human Nuclear Dutp Nucleotidohydrolase (Ndut)., Shawna M Rotoli, Julia L Jones, Salvatore J Caradonna Oct 2018

Cysteine Residues Contribute To The Dimerization And Enzymatic Activity Of Human Nuclear Dutp Nucleotidohydrolase (Ndut)., Shawna M Rotoli, Julia L Jones, Salvatore J Caradonna

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

dUTPase is an enzyme found in all organisms that have thymine as a constituent of DNA. Through evolution, humans have two major isoforms of dUTPase: a mitochondrial (mDut) and a nuclear (nDut) isoform. The nuclear isoform of dUTPase is a 164-amino-acids-long protein containing three cysteine residues. nDut's starting methionine is post-translationally cleaved, leaving four unique amino acids on its amino-terminus including one cysteine residue (C3). These are not present in the mitochondrial isoform (mDut). Using mass spectrometry analyses of recombinant dUTPase constructs, we have discovered an intermolecular disulfide bridge between cysteine-3 of each nDut monomer. We have found that these …


Escherichia Coli Itat Is A Type Ii Toxin That Inhibits Translation By Acetylating Isoleucyl-Trnaile, Brendan Wilcox, Ilya Osterman, Marina Serebryakova, Dmitry Lukyanov, Ekaterina Komarova, Bridget Gollan, Natalia Morozova, Yuri I Wolf, Kira S Makarova, Sophie Helaine, Petr Sergiev, Svetlana Dubiley, Sergei Borukhov, Konstantin Severinov Sep 2018

Escherichia Coli Itat Is A Type Ii Toxin That Inhibits Translation By Acetylating Isoleucyl-Trnaile, Brendan Wilcox, Ilya Osterman, Marina Serebryakova, Dmitry Lukyanov, Ekaterina Komarova, Bridget Gollan, Natalia Morozova, Yuri I Wolf, Kira S Makarova, Sophie Helaine, Petr Sergiev, Svetlana Dubiley, Sergei Borukhov, Konstantin Severinov

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Prokaryotic toxin-antitoxin (TA) modules are highly abundant and are involved in stress response and drug tolerance. The most common type II TA modules consist of two interacting proteins. The type II toxins are diverse enzymes targeting various essential intracellular targets. The antitoxin binds to cognate toxin and inhibits its function. Recently, TA modules whose toxins are GNAT-family acetyltransferases were described. For two such systems, the target of acetylation was shown to be aminoacyl-tRNA: the TacT toxin targets aminoacylated elongator tRNAs, while AtaT targets the amino acid moiety of initiating tRNAMet. We show that the itaRT gene pair from Escherichia coli …


N-Terminal Domain Of Human Uracil Dna Glycosylase (Hung2) Promotes Targeting To Uracil Sites Adjacent To Ssdna-Dsdna Junctions, Brian P Weiser, Gaddiel Rodriguez, Philip A Cole, James T Stivers Aug 2018

N-Terminal Domain Of Human Uracil Dna Glycosylase (Hung2) Promotes Targeting To Uracil Sites Adjacent To Ssdna-Dsdna Junctions, Brian P Weiser, Gaddiel Rodriguez, Philip A Cole, James T Stivers

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

The N-terminal domain (NTD) of nuclear human uracil DNA glycosylase (hUNG2) assists in targeting hUNG2 to replication forks through specific interactions with replication protein A (RPA). Here, we explored hUNG2 activity in the presence and absence of RPA using substrates with ssDNA-dsDNA junctions that mimic structural features of the replication fork and transcriptional R-loops. We find that when RPA is tightly bound to the ssDNA overhang of junction DNA substrates, base excision by hUNG2 is strongly biased toward uracils located 21 bp or less from the ssDNA-dsDNA junction. In the absence of RPA, hUNG2 still showed an 8-fold excision bias …


The Zinc Transporter Zipt-7.1 Regulates Sperm Activation In Nematodes, Yanmei Zhao, Chieh-Hsiang Tan, Amber Krauchunas, Andrea Scharf, Nicholas Dietrich, Kurt Warnhoff, Zhiheng Yuan, Marina Druzhinina, Sam Guoping Gu, Long Miao, Andrew Singson, Ronald E Ellis, Kerry Kornfeld Jun 2018

The Zinc Transporter Zipt-7.1 Regulates Sperm Activation In Nematodes, Yanmei Zhao, Chieh-Hsiang Tan, Amber Krauchunas, Andrea Scharf, Nicholas Dietrich, Kurt Warnhoff, Zhiheng Yuan, Marina Druzhinina, Sam Guoping Gu, Long Miao, Andrew Singson, Ronald E Ellis, Kerry Kornfeld

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Sperm activation is a fascinating example of cell differentiation, in which immotile spermatids undergo a rapid and dramatic transition to become mature, motile sperm. Because the sperm nucleus is transcriptionally silent, this transition does not involve transcriptional changes. Although Caenorhabditis elegans is a leading model for studies of sperm activation, the mechanisms by which signaling pathways induce this transformation remain poorly characterized. Here we show that a conserved transmembrane zinc transporter, ZIPT-7.1, regulates the induction of sperm activation in Caenorhabditis nematodes. The zipt-7.1 mutant hermaphrodites cannot self-fertilize, and males reproduce poorly, because mutant spermatids are defective in responding to activating …


Till Death Do Us Part: The Marriage Of Autophagy And Apoptosis., Katrina F Cooper May 2018

Till Death Do Us Part: The Marriage Of Autophagy And Apoptosis., Katrina F Cooper

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Autophagy is a widely conserved catabolic process that is necessary for maintaining cellular homeostasis under normal physiological conditions and driving the cell to switch back to this status quo under times of starvation, hypoxia, and oxidative stress. The potential similarities and differences between basal autophagy and stimulus-induced autophagy are still largely unknown. Both act by clearing aberrant or unnecessary cytoplasmic material, such as misfolded proteins, supernumerary and defective organelles. The relationship between reactive oxygen species (ROS) and autophagy is complex. Cellular ROS is predominantly derived from mitochondria. Autophagy is triggered by this event, and by clearing the defective organelles effectively, …


Persistent Stress-Induced Neuroplastic Changes In The Locus Coeruleus/Norepinephrine System, Olga Borodovitsyna, Neal Joshi, Daniel Chandler Jan 2018

Persistent Stress-Induced Neuroplastic Changes In The Locus Coeruleus/Norepinephrine System, Olga Borodovitsyna, Neal Joshi, Daniel Chandler

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Neural plasticity plays a critical role in mediating short- and long-term brain responses to environmental stimuli. A major effector of plasticity throughout many regions of the brain is stress. Activation of the locus coeruleus (LC) is a critical step in mediating the neuroendocrine and behavioral limbs of the stress response. During stressor exposure, activation of the hypothalamic-pituitary-adrenal axis promotes release of corticotropin-releasing factor in LC, where its signaling promotes a number of physiological and cellular changes. While the acute effects of stress on LC physiology have been described, its long-term effects are less clear. This review will describe how stress …


Snf1 Dependent Destruction Of Med13 Is Required For Programmed Cell Death Following Oxidative Stress In Yeast, Stephen D Willis, David C Stieg, R. Shah, Randy Strich, Katrina F Cooper Dec 2017

Snf1 Dependent Destruction Of Med13 Is Required For Programmed Cell Death Following Oxidative Stress In Yeast, Stephen D Willis, David C Stieg, R. Shah, Randy Strich, Katrina F Cooper

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

All eukaryotic cells, when faced with unfavorable environmental conditions, have to decide whether to mount a survival or cell death response. The conserved cyclin C and its kinase partner Cdk8 play a key role in this decision. Both are members of the Cdk8 kinase module that, along with Med12 and Med13, associate with the core mediator complex of RNA polymerase II. In S. cerevisiae, oxidative stress triggers Med13 destruction1, which thereafter releases cyclin Ci nto the cytoplasm. Cytoplasmic cyclin C associates with mitochondria where it induces hyper-fragmentation and programmed cell death2. This suggests a model in …


Mechanism Of Transcription Anti-Termination In Human Mitochondria., Hauke S Hillen, Andrey V Parshin, Karen Agaronyan, Yaroslav I Morozov, James J Graber, Aleksandar Chernev, Kathrin Schwinghammer, Henning Urlaub, Michael Anikin, Patrick Cramer, Dmitry Temiakov Nov 2017

Mechanism Of Transcription Anti-Termination In Human Mitochondria., Hauke S Hillen, Andrey V Parshin, Karen Agaronyan, Yaroslav I Morozov, James J Graber, Aleksandar Chernev, Kathrin Schwinghammer, Henning Urlaub, Michael Anikin, Patrick Cramer, Dmitry Temiakov

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

In human mitochondria, transcription termination events at a G-quadruplex region near the replication origin are thought to drive replication of mtDNA by generation of an RNA primer. This process is suppressed by a key regulator of mtDNA-the transcription factor TEFM. We determined the structure of an anti-termination complex in which TEFM is bound to transcribing mtRNAP. The structure reveals interactions of the dimeric pseudonuclease core of TEFM with mobile structural elements in mtRNAP and the nucleic acid components of the elongation complex (EC). Binding of TEFM to the DNA forms a downstream "sliding clamp," providing high processivity to the EC. …


Endonucleolytic Cleavage In The Expansion Segment 7 Of 25s Rrna Is An Early Marker Of Low-Level Oxidative Stress In Yeast, Daniel Shedlovskiy, Jessica A Zinskie, Ethan Gardner, Dimitri G Pestov, Natalia Shcherbik Nov 2017

Endonucleolytic Cleavage In The Expansion Segment 7 Of 25s Rrna Is An Early Marker Of Low-Level Oxidative Stress In Yeast, Daniel Shedlovskiy, Jessica A Zinskie, Ethan Gardner, Dimitri G Pestov, Natalia Shcherbik

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

The ability to detect and respond to oxidative stress is crucial to the survival of living organisms. In cells, sensing of increased levels of reactive oxygen species (ROS) activates many defensive mechanisms that limit or repair damage to cell components. The ROS-signaling responses necessary for cell survival under oxidative stress conditions remain incompletely understood, especially for the translational machinery. Here, we found that drug treatments or a genetic deficiency in the thioredoxin system that increase levels of endogenous hydrogen peroxide in the yeast Saccharomyces cerevisiae promote site-specific endonucleolytic cleavage in 25S ribosomal RNA (rRNA) adjacent to the c loop of …


Inhibition Of Post-Transcriptional Steps In Ribosome Biogenesis Confers Cytoprotection Against Chemotherapeutic Agents In A P53-Dependent Manner, Russell T Sapio, Anastasiya N Nezdyur, Matthew Krevetski, Leonid Anikin, Vincent J Manna, Natalie Minkovsky, Dimitri G Pestov Aug 2017

Inhibition Of Post-Transcriptional Steps In Ribosome Biogenesis Confers Cytoprotection Against Chemotherapeutic Agents In A P53-Dependent Manner, Russell T Sapio, Anastasiya N Nezdyur, Matthew Krevetski, Leonid Anikin, Vincent J Manna, Natalie Minkovsky, Dimitri G Pestov

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

The p53-mediated nucleolar stress response associated with inhibition of ribosomal RNA transcription was previously shown to potentiate killing of tumor cells. Here, we asked whether targeting of ribosome biogenesis can be used as the basis for selective p53-dependent cytoprotection of nonmalignant cells. Temporary functional inactivation of the 60S ribosome assembly factor Bop1 in a 3T3 cell model markedly increased cell recovery after exposure to camptothecin or methotrexate. This was due, at least in part, to reversible pausing of the cell cycle preventing S phase associated DNA damage. Similar cytoprotective effects were observed after transient shRNA-mediated silencing of Rps19, but not …