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Articles 121 - 150 of 155

Full-Text Articles in Medical Toxicology

The Role Of Xpg In Processing (Cag)N/(Ctg)N Dna Hairpins, Caixia Hou, Tianyi Zhang, Lei Tian, Jian Huang, Liya Gu, Guo-Min Li Mar 2011

The Role Of Xpg In Processing (Cag)N/(Ctg)N Dna Hairpins, Caixia Hou, Tianyi Zhang, Lei Tian, Jian Huang, Liya Gu, Guo-Min Li

Toxicology and Cancer Biology Faculty Publications

BACKGROUND: During DNA replication or repair, disease-associated (CAG)n/(CTG)n expansion can result from formation of hairpin structures in the repeat tract of the newly synthesized or nicked DNA strand. Recent studies identified a nick-directed (CAG)n/(CTG)n hairpin repair (HPR) system that removes (CAG)n/(CTG)n hairpins from human cells via endonucleolytic incisions. Because the process is highly similar to the mechanism by which XPG and XPF endonucleases remove bulky DNA lesions during nucleotide excision repair, we assessed the potential role of XPG in conducting (CAG)n/(CTG)n HPR.

RESULTS: To determine if the XPG endonuclease is involved in (CAG)n/(CTG)n hairpin removal, two XPG-deficient cell lines (GM16024 …


Androgen Increases Angiotensin Receptor Type 1a On Smooth Muscle Cells To Promote Angiotensin Ii-Induced Abdominal Aortic Aneurysms, Xuan Zhang Jan 2011

Androgen Increases Angiotensin Receptor Type 1a On Smooth Muscle Cells To Promote Angiotensin Ii-Induced Abdominal Aortic Aneurysms, Xuan Zhang

University of Kentucky Doctoral Dissertations

The purpose of this study was to determine whether androgen promotes AT1aR expression on smooth muscle to confer high prevalence of AngII-induced AAAs in hyperlipidemic mice. In addition, we also investigate the role of androgen in the progression of established AngII-induced AAAs.

First, we sought to examine the role of endogenous androgen in the growth of established AngII-induced AAAs. By castrating male mice, we demonstrated that removal of endogenous androgen significantly decreased the progressive lumen dilation of established AngII-induced AAAs in male ApoE-/- mice, but had no effect on external AAA diameters. These results suggest that androgen contributes to the …


Identification Of Activities Involved In Cag/Ctg Repeat Instability, Nelson Lap Shun Chan Jan 2011

Identification Of Activities Involved In Cag/Ctg Repeat Instability, Nelson Lap Shun Chan

University of Kentucky Doctoral Dissertations

CAG/CTG repeat instability is associated with at least 14 neurological disorders, including Huntington’s disease and Myotonic dystrophy type 1. In vitro and in vivo studies have showed that CAG/CTG repeats form a stable hairpin that is believed to be the intermediate for repeat expansion and contraction.

Addition of extra DNA is essential for repeat expansion, so DNA synthesis is one of the keys for repeat expansion. In vivo studies reveal that 3’ CTG slippage with subsequent hairpin formation (henceforth called the 3’ CTG slippage hairpin) occurs during DNA synthesis. It is proposed that hairpin tolerance machinery is activated because prolonged …


Mir-17* Suppresses Tumorigenicity Of Prostate Cancer By Inhibiting Mitochondrial Antioxidant Enzymes, Yong Xu, Fang Fang, Jiayou Zhang, Sajni Josson, William H. St. Clair, Daret K. St. Clair Dec 2010

Mir-17* Suppresses Tumorigenicity Of Prostate Cancer By Inhibiting Mitochondrial Antioxidant Enzymes, Yong Xu, Fang Fang, Jiayou Zhang, Sajni Josson, William H. St. Clair, Daret K. St. Clair

Toxicology and Cancer Biology Faculty Publications

Aberrant micro RNA (miRNA) expression has been implicated in the pathogenesis of cancer. Recent studies have shown that the miR-17-92 cluster is overexpressed in many types of cancer. The oncogenic function of mature miRNAs encoded by the miR-17-92 cluster has been identified from the 5' arm of six precursors. However, the function of the miRNAs produced from the 3' arm of these precursors remains unknown. The present study demonstrates that miR-17* is able to suppress critical primary mitochondrial antioxidant enzymes, such as manganese superoxide dismutase (MnSOD), glutathione peroxidase-2 (GPX2) and thioredoxin reductase-2 (TrxR2). Transfection of miR-17* into prostate cancer PC-3 …


The Catalytic Function Of The Rev1 Dcmp Transferase Is Required In A Lesion-Specific Manner For Translesion Synthesis And Base Damage-Induced Mutagenesis, Ying Zhou, Jillian Wang, Yanbin Zhang, Zhigang Wang Aug 2010

The Catalytic Function Of The Rev1 Dcmp Transferase Is Required In A Lesion-Specific Manner For Translesion Synthesis And Base Damage-Induced Mutagenesis, Ying Zhou, Jillian Wang, Yanbin Zhang, Zhigang Wang

Toxicology and Cancer Biology Faculty Publications

The Rev1-Polζ pathway is believed to be the major mechanism of translesion DNA synthesis and base damage-induced mutagenesis in eukaryotes. While it is widely believed that Rev1 plays a non-catalytic function in translesion synthesis, the role of its dCMP transferase activity remains uncertain. To determine the relevance of its catalytic function in translesion synthesis, we separated the Rev1 dCMP transferase activity from its non-catalytic function in yeast. This was achieved by mutating two conserved amino acid residues in the catalytic domain of Rev1, i.e. D467A/E468A, where its catalytic function was abolished but its non-catalytic function remained intact. In this mutant …


Acetylation Of Wrn Protein Regulates Its Stability By Inhibiting Ubiquitination, Kai Li, Rui Wang, Enerlyn Lozada, Wei Fan, David K. Orren, Jianyuan Luo Apr 2010

Acetylation Of Wrn Protein Regulates Its Stability By Inhibiting Ubiquitination, Kai Li, Rui Wang, Enerlyn Lozada, Wei Fan, David K. Orren, Jianyuan Luo

Toxicology and Cancer Biology Faculty Publications

BACKGROUND: WRN is a multi-functional protein involving DNA replication, recombination and repair. WRN acetylation has been demonstrated playing an important role in response to DNA damage. We previously found that WRN acetylation can regulate its enzymatic activities and nuclear distribution.

METHODOLOGY/PRINCIPAL FINDING: Here, we investigated the factors involved in WRN acetylation and found that CBP and p300 are the only major acetyltransferases for WRN acetylation. We further identified 6 lysine residues in WRN that are subject to acetylation. Interestingly, WRN acetylation can increase its protein stability. SIRT1-mediated deacetylation of WRN reverses this effect. CBP dramatically increases the half-life of wild …


Structural Instability Of Human Ribosomal Rna Gene Clusters, Dawn Michelle Stults Jan 2010

Structural Instability Of Human Ribosomal Rna Gene Clusters, Dawn Michelle Stults

University of Kentucky Doctoral Dissertations

The human ribosomal RNA genes are critically important for cell metabolism and viability. They code for the catalytic RNAs which, encased in a housing of more than 80 ribosomal proteins, link together amino acids by peptide bonds to generate all cellular proteins. Because the RNAs are not repeatedly translated, as is the case with messenger RNAs, multiple copies are required. The genes which code for the human ribosomal RNAs (rRNAs) are arranged as clusters of tandemly repeated sequences. Three of four catalytic RNAs are spliced from a single transcript. The genes are located on the short arms of the five …


The Radiosensitization Effect Of Parthenolide In Prostate Cancer: Implications For Selective Cancer Killing By Modulation Of Intracellular Redox State, Yulan Sun Jan 2010

The Radiosensitization Effect Of Parthenolide In Prostate Cancer: Implications For Selective Cancer Killing By Modulation Of Intracellular Redox State, Yulan Sun

University of Kentucky Doctoral Dissertations

Parthenolide (PN), a major active component of the traditional herbal medicine feverfew, has been shown to have anti-inflammatory and anti-tumor properties. More remarkably, the cytotoxicity of PN seems selective to tumor cells but not their normal cell counterparts. In the present study, we investigate whether and how PN selectively enhances tumor sensitivity to radiation therapy by using prostate cancer cells LNCaP, DU145 and PC3, as well as normal prostate epithelial cells PrEC.

Our study demonstrates that inhibition of NF-κB pathway and suppression of its downstream target MnSOD are common mechanisms for the radiosensitization effect of PN in prostate cancer cells. …


Biochemical Characterization Of Human Mismatch Recognition Proteins Mutsα And Mutsβ, Lei Tian Jan 2010

Biochemical Characterization Of Human Mismatch Recognition Proteins Mutsα And Mutsβ, Lei Tian

University of Kentucky Doctoral Dissertations

The integrity of an organism's genome depends on the fidelity of DNA replication and the efficiency of DNA repair. The DNA mismatch repair (MMR) system, which is highly conserved from prokaryotes to eukaryotes, plays an important role in maintaining genome stability by correcting base-base mismatches and insertion/deletion (ID) mispairs generated during DNA replication and other DNA transactions. Mismatch recognition is a critical step in MMR. Two mismatch recognition proteins, MutSα (MSH2-MSH6 heterodimer) and MutSβ (MSH2-MSH3 heterodimer), have been identified in eukaryotic cells. MutSα and MutSβ have partially overlapping functions, with MutSα recognizing primarily base-base mismatches and 1-2 nt ID mispairs …


Function Of Androgen Receptor In Prostate Cancer Epithelial Mesenchymal Transition And Microtubule Targeting, Menglei Zhu Jan 2010

Function Of Androgen Receptor In Prostate Cancer Epithelial Mesenchymal Transition And Microtubule Targeting, Menglei Zhu

University of Kentucky Doctoral Dissertations

Prostate cancer is the most frequently diagnosed non-skin cancer and the third leading cause of cancer mortality among men in the US. Androgens are functionally required for the normal growth of the prostate gland and play a critical role in prostate tumor development and progression. Epithelial-mesenchymal-transition (EMT) is an important process during normal development, and cancer cell metastasis.

This study examined the ability of androgens to influence EMT of prostate cancer epithelial cells and evaluate the effect of taxol chemotherapy on androgen signaling in prostate cancer cells in prostate cancer. The EMT pattern was evaluated on the basis of expression …


Jnk1 Activation Predicts The Prognostic Outcome Of The Human Hepatocellular Carcinoma, Qingshan Chang, Jianguo Chen, Kevin J. Beezhold, Vince Castranova, Xianglin Shi, Fei Chen Aug 2009

Jnk1 Activation Predicts The Prognostic Outcome Of The Human Hepatocellular Carcinoma, Qingshan Chang, Jianguo Chen, Kevin J. Beezhold, Vince Castranova, Xianglin Shi, Fei Chen

Toxicology and Cancer Biology Faculty Publications

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide with an extremely poor prognosis. The classification of HCC based on the molecular signature is not well-established.

RESULTS: In the present study, we reported HCC signature genes based on the JNK1 activation status in 31 HCC specimens relative to the matched distal noncancerous liver tissue from 31 patients. The HCCs with high JNK1 (H-JNK1) and low JNK1 (L-JNK1) were sub-grouped. Two different signature gene sets for both H-JNK1 and L-JNK1 HCC were identified through gene expression profiling. A striking overlap of signature genes was observed between the H-JNK1 …


Metallic Nickel Nano- And Fine Particles Induce Jb6 Cell Apoptosis Through A Caspase-8/Aif Mediated Cytochrome C-Independent Pathway, Jinshun Zhao, Linda Bowman, Xingdong Zhang, Xianglin Shi, Binghua Jiang, Vincent Castranova, Min Ding Apr 2009

Metallic Nickel Nano- And Fine Particles Induce Jb6 Cell Apoptosis Through A Caspase-8/Aif Mediated Cytochrome C-Independent Pathway, Jinshun Zhao, Linda Bowman, Xingdong Zhang, Xianglin Shi, Binghua Jiang, Vincent Castranova, Min Ding

Toxicology and Cancer Biology Faculty Publications

BACKGROUND: Carcinogenicity of nickel compounds has been well documented. However, the carcinogenic effect of metallic nickel is still unclear. The present study investigates metallic nickel nano- and fine particle-induced apoptosis and the signal pathways involved in this process in JB6 cells. The data obtained from this study will be of benefit for elucidating the pathological and carcinogenic potential of metallic nickel particles.

RESULTS: Using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, we found that metallic nickel nanoparticles exhibited higher cytotoxicity than fine particles. Both metallic nickel nano- and fine particles induced JB6 cell apoptosis. Metallic nickel nanoparticles produced higher apoptotic induction than fine …


Dna Instability In Replicating Huntington's Disease Lymphoblasts, Milena Cannella, Vittorio Maglione, Tiziana Martino, Giuseppe Ragona, Luigi Frati, Guo-Min Li, Ferdinando Squitieri Feb 2009

Dna Instability In Replicating Huntington's Disease Lymphoblasts, Milena Cannella, Vittorio Maglione, Tiziana Martino, Giuseppe Ragona, Luigi Frati, Guo-Min Li, Ferdinando Squitieri

Toxicology and Cancer Biology Faculty Publications

BACKGROUND: The expanded CAG repeat in the Huntington's disease (HD) gene may display tissue-specific variability (e.g. triplet mosaicism) in repeat length, the longest mutations involving mitotic (germ and glial cells) and postmitotic (neurons) cells. What contributes to the triplet mutability underlying the development of HD nevertheless remains unknown. We investigated whether, besides the increased DNA instability documented in postmitotic neurons, possible environmental and genetic mechanisms, related to cell replication, may concur to determine CAG repeat mutability. To test this hypothesis we used, as a model, cultured HD patients' lymphoblasts with various CAG repeat lengths.

RESULTS: Although most lymphoblastoid cell lines …


Role Of Mel-18 In Regulating Protein Sumoylation And Identification Of A New Polymorphism In Bmi-1, Jie Zhang Jan 2009

Role Of Mel-18 In Regulating Protein Sumoylation And Identification Of A New Polymorphism In Bmi-1, Jie Zhang

University of Kentucky Doctoral Dissertations

Small ubiquitin-like modifier (SUMO) regulates numerous biological functions. In a previous study we found that sumoylation of HSF2 is involved in regulating HSF2 bookmarking function, but the mechanism that mediates this regulation was unknown. The results in my work support the intriguing hypothesis that polycomb protein, Mel-18, actually functions as an anti-SUMO E3 protein, interacting both with HSF2 and the SUMO E2 Ubc9, but acting to inhibit Ubc9 activity and thereby decrease sumoylation of the HSF2.

This study also suggested that Mel-18 negatively regulates the sumoylation of other cellular proteins, and we extend its targets to RanGAP1 protein. The results …


Role Of Oxidative Stress And T Cell Homing In The Development Of Murine Syngeneic Graft-Versus-Host Disease, Jacqueline Perez-Rodriguez Jan 2009

Role Of Oxidative Stress And T Cell Homing In The Development Of Murine Syngeneic Graft-Versus-Host Disease, Jacqueline Perez-Rodriguez

University of Kentucky Doctoral Dissertations

Syngeneic graft-versus-host disease (SGVHD) is induced by reconstituting lethally irradiated mice with syngeneic BM cells followed by a 21 day treatment with the immunosuppressive agent cyclosporine A (CsA). Clinical symptoms of the disease appear 2-3 weeks following cessation of CsA therapy and disease-associated inflammation occurs primarily in the colon and liver.

The development of SGVHD is a complex process resulting from the cooperative interaction of multiple effector cell populations including NK cells, T cells and macrophages. TH1 cytokines (IL-12, TNF-α, IFN- γ), produced by these effector cells, serve as inflammatory mediators contributing to the pathogenesis of SGVHD. The …


Angiotensin Ii Induction Of Regional Effects In Murine Vasculature, Albert Phillip Owens Iii Jan 2009

Angiotensin Ii Induction Of Regional Effects In Murine Vasculature, Albert Phillip Owens Iii

University of Kentucky Doctoral Dissertations

The renin angiotensin system (RAS) exerts many diverse physiological functions throughout the body, mediated by its effector peptide, angiotensin II (AngII). AngII has been linked with a variety of different functions ranging from the initiation of severe vascular pathologies, such as atherosclerosis and abdominal aortic aneurysm (AAA), to mundane physiological processes of fluid homeostasis, vascular contraction, and regulation of blood pressure. To provide a potential link between these functions, an in-depth analysis of regional effects of AngII on aortic vasculature was performed.

The studies presented in this dissertation tested the overall hypothesis of whether regional changes exist in the vasculature …


Implications For The Hsf2/Prc1 Interaction And Regulation Of Condensin By Phosphorylation During Mitosis, Lynea Alene Murphy Jan 2008

Implications For The Hsf2/Prc1 Interaction And Regulation Of Condensin By Phosphorylation During Mitosis, Lynea Alene Murphy

University of Kentucky Doctoral Dissertations

At the beginning of mitosis, chromosomes are condensed and segregated to facilitate correct alignment later in cytokinesis. Condensin is the pentameric enzyme responsible for this DNA compaction and is composed of two structural maintenance of chromosomes (SMC) subunits and three non-SMC subunits. Condensin mutations generate chromosomal abnormalities due to improper segregation, leading to genome instability and eventual malignant transformation of the cell. Cdc2 phosphorylation of the non-SMC subunits, CAP-G, CAP-D2, and CAP-H, has been demonstrated to be important for condensin supercoiling activity and function. While these subunits are thought to be phosphorylated by Cdc2, the exact sites have not yet …


Nitration And Inactivation Of Manganese Superoxide Dismutase Plays A Critical Role In Metabolic Switch, Muthuswamy Anantharaman Jan 2008

Nitration And Inactivation Of Manganese Superoxide Dismutase Plays A Critical Role In Metabolic Switch, Muthuswamy Anantharaman

University of Kentucky Doctoral Dissertations

Alzheimer’s disease (AD) is a multifactorial, progressive, age-related neurodegenerative disease. Oxidative stress hypothesis is most prevalent and is gaining significant support. Inspite of the progress achieved on oxidative stress related damages in AD brain; the modification occurring on the various cellular antioxidant enzymes antioxidant has not been identified. Tyrosine nitration, a marker for peroxynitrite induced oxidative damage to protein is widespread in AD brain and Manganese superoxide dismutase (MnSOD), primary mitochondrial antioxidant enzyme is prone to peroxynitrite induced nitration and inactivation. Nitration of proteins involved in energy metabolism has been demonstrated in AD brain, which may explain the altered glucose …


Reciprocal Regulation Of Par-4 And Caspase-8 In The Trail Signaling Pathway, Padhma Ranganathan Jan 2008

Reciprocal Regulation Of Par-4 And Caspase-8 In The Trail Signaling Pathway, Padhma Ranganathan

University of Kentucky Doctoral Dissertations

Par‐4 is a pro‐apoptotic tumor suppressor that is mutated, suppressed or inactivated in cancer. Par‐4 exploits components of the extrinsic pathway to cause apoptosis selectively of cancer cells. This study identified Par‐4 as an essential component of the apoptotic pathway induced by TRAIL, which selectively targets cancer cells. RNA interference‐mediated knockdown of Par‐4 rendered cancer cells unresponsive to TRAIL‐induced apoptosis. Cells with knocked‐down levels of Par‐4 were deficient in the activation of the apoptosis‐initiator caspase‐8 and the apoptosis‐effector caspase‐3 in response to TRAIL. Par‐4 was identified as a critical mediator of membrane translocation of caspase‐8 and the adapter protein FADD. …


Endothelial Cell Dysfunction By Environmental Contaminants, Elizabeth Grace Oesterling Jan 2008

Endothelial Cell Dysfunction By Environmental Contaminants, Elizabeth Grace Oesterling

University of Kentucky Doctoral Dissertations

Within the last few decades, epidemiological evidence has linked exposure to air pollution, both its particles and its organic components, with cardiovascular disease (CVD) progression. CVD is a life long disease with the disruption of the endothelium being the inaugural event in this inflammatory process. The vascular endothelium is extremely susceptible to environmental insults given its tremendous surface area and that it is in constant contact with blood and components circulating within the blood, including xenobiotics. The endothelium is important as a barrier from blood constituents however, dysfunction of this barrier leads to the influx of lymphocytes and granulocytes that …


Translational Regulatory Mechanisms Of The Rat And Human Multidrug Resistance Protein 2, Yuanyuan Zhang Jan 2008

Translational Regulatory Mechanisms Of The Rat And Human Multidrug Resistance Protein 2, Yuanyuan Zhang

University of Kentucky Doctoral Dissertations

Multidrug resistance protein 2 (MRP2) is the second member the C subfamily in the superfamily of adenosine triphosphate (ATP)-binding cassette (ABC) efflux transporters. MRP2 is a critical player for generation of bile acidindependent bile flow and biliary excretion of glutathione, glucuronate and sulfate conjugates of endo- and xenobiotics. Dysfunctional expression of MRP2 is associated with Dubin-Johnson Syndrome.

Pathological and physiological states or xenobiotics change the MRP2 expression level. Under some conditions, expression of the human MRP2 and rat Mrp2 proteins are regulated at the translation level. There are several transcription initiation sites in MRP2/Mrp2 gene. The 5’ untranslated regions (5’UTRs) …


Zinc Deficiency And Mechanisms Of Endothelial Cell Dysfunction, Huiyun Shen Jan 2008

Zinc Deficiency And Mechanisms Of Endothelial Cell Dysfunction, Huiyun Shen

University of Kentucky Doctoral Dissertations

Atherosclerosis is a chronic inflammatory disease thought to be initiated by endothelial cell dysfunction. Research described in this dissertation is focused on the role of zinc deficiency in endothelial cell activation with an emphasis on the function of the transcription factors nuclear factor-κB (NF-κB), peroxisome proliferator activated receptor (PPAR), and the aryl hydrocarbon receptor (AhR), which all play critical roles in the early pathology of atherosclerosis. Cultured porcine aortic vascular endothelial cells were deprived of zinc by the zinc chelator TPEN and/or treated with the NF-κB inhibitor CAPE or the PPARγ agonist rosiglitazone, followed by measurements of PPARα expression, cellular …


Suppression Of Peroxisomal Enzyme Activities And Cytochrome P450 4a Isozyme Expression By Congeneric Polybrominated And Polychlorinated Biphenyls, Larry W. Robertson, Isabelle Berberian, Tim Borges, Li-Chuan Chen, Ching K. Chow, Howard P. Glauert, Johannes G. Filser, Helmut Thomas Sep 2007

Suppression Of Peroxisomal Enzyme Activities And Cytochrome P450 4a Isozyme Expression By Congeneric Polybrominated And Polychlorinated Biphenyls, Larry W. Robertson, Isabelle Berberian, Tim Borges, Li-Chuan Chen, Ching K. Chow, Howard P. Glauert, Johannes G. Filser, Helmut Thomas

Toxicology and Cancer Biology Faculty Publications

The purpose of this study was to determine the effects of PCBs and PBBs on peroxisome proliferator-activated receptor-alpha-(PPARalpha-) associated enzyme activities or protein levels. Male Sprague-Dawley rats were administered a single IP injection (150 mu mol/kg) of either 3,3',4,4'-tetrabromobiphenyl, 3,3',4,4'-tetrachlorobiphenyl, 3,3',5,5'-tetrabromobiphenyl, 2',3,3',4,5-pentachlorobiphenyl, 3,3',4,4',5-pentachlorobiphenyl, 2,2',3,3',5,5'-hexachlorobiphenyl, or 3,3',4,4',5,5'-hexabromobiphenyl in corn oil (10 ml/kg). One week later, the activities of catalase, peroxisomal fatty acyl-CoA oxidase, and peroxisomal beta-oxidation as well as cytochrome P450 4A (CYP4A) protein content were determined in subcellular liver fractions. None of the peroxisomal enzyme activities were significantly increased by any of the halogenated biphenyl congeners tested. Except for minor …


Replication Fork Regression In Vitro By The Werner Syndrome Protein (Wrn): Holliday Junction Formation, The Effect Of Leading Arm Structure And A Potential Role For Wrn Exonuclease Activity, Amrita Machwe, Liren Xiao, Robert G Lloyd, Edward Bolt, David K. Orren Jan 2007

Replication Fork Regression In Vitro By The Werner Syndrome Protein (Wrn): Holliday Junction Formation, The Effect Of Leading Arm Structure And A Potential Role For Wrn Exonuclease Activity, Amrita Machwe, Liren Xiao, Robert G Lloyd, Edward Bolt, David K. Orren

Toxicology and Cancer Biology Faculty Publications

The premature aging and cancer-prone disease Werner syndrome stems from loss of WRN protein function. WRN deficiency causes replication abnormalities, sensitivity to certain genotoxic agents, genomic instability and early replicative senescence in primary fibroblasts. As a RecQ helicase family member, WRN is a DNA-dependent ATPase and unwinding enzyme, but also possesses strand annealing and exonuclease activities. RecQ helicases are postulated to participate in pathways responding to replication blockage, pathways possibly initiated by fork regression. In this study, a series of model replication fork substrates were used to examine the fork regression capability of WRN. Our results demonstrate that WRN catalyzes …


Identification And Characterization Of Ogg1 Mutations In Patients With Alzheimer's Disease, Guogen Mao, Xiaoyu Pan, Beibei Zhu, Yanbin Zhang, Fenghua Yuan, Jian Huang, Mark A. Lovell, Maxwell P. Lee, William R. Markesbery, Guo-Min Li, Liya Gu Jan 2007

Identification And Characterization Of Ogg1 Mutations In Patients With Alzheimer's Disease, Guogen Mao, Xiaoyu Pan, Beibei Zhu, Yanbin Zhang, Fenghua Yuan, Jian Huang, Mark A. Lovell, Maxwell P. Lee, William R. Markesbery, Guo-Min Li, Liya Gu

Toxicology and Cancer Biology Faculty Publications

Patients with Alzheimer's disease (AD) exhibit higher levels of 8-oxo-guanine (8-oxoG) DNA lesions in their brain, suggesting a reduced or defective 8-oxoG repair. To test this hypothesis, this study investigated 14 AD patients and 10 age-matched controls for mutations of the major 8-oxoG removal gene OGG1. Whereas no alterations were detected in any control samples, four AD patients exhibited mutations in OGG1, two carried a common single base (C796) deletion that alters the carboxyl terminal sequence of OGG1, and the other two had nucleotide alterations leading to single amino acid substitutions. In vitro biochemical assays revealed …


Length-Dependent Degradation Of Single-Stranded 3' Ends By The Werner Syndrome Protein (Wrn): Implications For Spatial Orientation And Coordinated 3' To 5' Movement Of Its Atpase/Helicase And Exonuclease Domains, Amrita Machwe, Liren Xiao, David K. Orren Feb 2006

Length-Dependent Degradation Of Single-Stranded 3' Ends By The Werner Syndrome Protein (Wrn): Implications For Spatial Orientation And Coordinated 3' To 5' Movement Of Its Atpase/Helicase And Exonuclease Domains, Amrita Machwe, Liren Xiao, David K. Orren

Toxicology and Cancer Biology Faculty Publications

BACKGROUND: The cancer-prone and accelerated aging disease Werner syndrome is caused by loss of function of the WRN gene product that possesses ATPase, 3' to 5' helicase and 3' to 5' exonuclease activities. Although WRN has been most prominently suggested to function in telomere maintenance, resolution of replication blockage and/or recombinational repair, its exact role in DNA metabolism remains unclear. WRN is the only human RecQ family member to possess both helicase and exonuclease activity, but the mechanistic relationship between these activities is unknown. In this study, model single-stranded and 3' overhang DNA substrates of varying length and structure were …


Competition Between The Dna Unwinding And Strand Pairing Activities Of The Werner And Bloom Syndrome Proteins, Amrita Machwe, Enerlyn M. Lozada, Liren Xiao, David K. Orren Jan 2006

Competition Between The Dna Unwinding And Strand Pairing Activities Of The Werner And Bloom Syndrome Proteins, Amrita Machwe, Enerlyn M. Lozada, Liren Xiao, David K. Orren

Toxicology and Cancer Biology Faculty Publications

BACKGROUND: The premature aging and cancer-prone Werner and Bloom syndromes are caused by defects in the RecQ helicase enzymes WRN and BLM, respectively. Recently, both WRN and BLM (as well as several other RecQ members) have been shown to possess a strand annealing activity in addition to the requisite DNA unwinding activity. Since an annealing function would appear to directly oppose the action of a helicase, we have examined in this study the dynamic equilibrium between unwinding and annealing mediated by either WRN or BLM.

RESULTS: Our investigation into the competition between annealing and unwinding demonstrates that, under standard reaction …


26Al-Containing Acidic And Basic Sodium Aluminum Phosphate Preparation And Use In Studies Of Oral Aluminum Bioavailability From Foods Utilizing 26Al As An Aluminum Tracer, Robert A. Yokel, Aaron A. Urbas, Robert A. Lodder, John P. Selegue, Rebecca L. Florence Apr 2005

26Al-Containing Acidic And Basic Sodium Aluminum Phosphate Preparation And Use In Studies Of Oral Aluminum Bioavailability From Foods Utilizing 26Al As An Aluminum Tracer, Robert A. Yokel, Aaron A. Urbas, Robert A. Lodder, John P. Selegue, Rebecca L. Florence

Pharmaceutical Sciences Faculty Publications

We synthesized 26Al-containing acidic and basic (alkaline) sodium aluminum phosphates (SALPs) which are FDA-approved leavening and emulsifying agents, respectively, and used them to determine the oral bioavailability of aluminum incorporated in selected foods. We selected applicable methods from published syntheses (patents) and scaled them down (∼3000- and 850-fold) to prepare ∼300–400 mg of each SALP. The 26Al was incorporated at the beginning of the syntheses to maximize 26Al and 27Al equilibration and incorporate the 26Al in the naturally-occurring Al-containing chemical species of the products. Near infrared spectroscopy (NIR) and X-ray powder diffraction (XRD) were used …


Mechanism Of Cancer Selective Apoptosis By Par-4, Sushma Gurumurthy Jan 2005

Mechanism Of Cancer Selective Apoptosis By Par-4, Sushma Gurumurthy

University of Kentucky Doctoral Dissertations

Despite distinct dissimilarities, diverse cancers express several common pro-tumorigenic traits. We present here evidence that the pro-apoptotic protein Par-4 utilizes one such common tumorigenic trait to become selectively activated and induce apoptosis in cancer cells. Elevated PKA activity noted in cancer cells activated the apoptotic function of ectopic Par-4 or its SAC domain, which induces apoptosis selectively in cancer cells and not in normal or immortalized cells. PKA preferentially phosphorylated Par-4 at the T155 residue within the SAC domain in cancer cells. Moreover, pharmacological-, peptide- or siRNA-mediated inhibition of PKA activity in cancer cells resulted in abrogation of both T155 …


Nucleic Acid Encoding Human Rev1 Protein, Zhigang Wang, Winston Lin, Hua Xin, Xiaohua Wu Jan 2004

Nucleic Acid Encoding Human Rev1 Protein, Zhigang Wang, Winston Lin, Hua Xin, Xiaohua Wu

Toxicology and Cancer Biology Faculty Patents

The present invention relates to a human cDNA homologous to the yeast REV1 gene. The sequence of human REV1 (hREV1) gene is described.