Life Sciences Commons^™

Mtorc2 Is Required For Rit-Mediated Oxidative Stress Resistance, Weikang Cai, Douglas A. Andres

Molecular and Cellular Biochemistry Faculty Publications

Rit, a member of the Ras family of GTPases, has been shown to promote cell survival in response to oxidative stress, in part by directing an evolutionarily conserved p38 MAPK-Akt survival cascade. Aberrant Rit signaling has recently been implicated as a driver mutation in human cancer, adding importance to the characterization of critical Rit effector pathways. However, the mechanism by which Rit-p38 signaling regulated Akt activity was unknown. Here, we identify mTORC2 as a critical downstream mediator of Rit-dependent survival signaling in response to reactive oxygen species (ROS) stress. Rit interacts with Sin1 (MAPKAP1), and Rit loss compromises ROS-dependent mTORC2 …

Cd151-Α3Β1 Integrin Complexes Suppress Ovarian Tumor Growth By Repressing Slug-Mediated Emt And Canonical Wnt Signaling, Lauren A. Baldwin, John T. Hoff, Jason Lefringhouse, Michael Zhang, Changhe Jia, Zeyi Liu, Sonia Erfani, Hongyan Jin, Mei Xu, Qing-Bai She, John R. Van Nagell Jr., Chi Wang, Li Chen, Rina Plattner, David M. Kaetzel, Jia Luo, Michael Lu, Dava West, Chunming Liu, Fred R. Ueland, Ronny Drapkin, Binhua P. Zhou, Xiuwei H. Yang

Pharmacology and Nutritional Sciences Faculty Publications

Human ovarian cancer is diagnosed in the late, metastatic stages but the underlying mechanisms remain poorly understood. We report a surprising functional link between CD151-α3β1 integrin complexes and the malignancy of serous-type ovarian cancer. Analyses of clinical specimens indicate that CD151 expression is significantly reduced or diminished in 90% of metastatic lesions, while it remains detectable in 58% of primary tumors. These observations suggest a putative tumor-suppressing role of CD151 in ovarian cancer. Indeed, our analyses show that knocking down CD151 or α3 integrin enhances tumor cell proliferation, growth and ascites production in nude mice. These changes are accompanied by …

Transcription Of The Streptococcus Pyogenes Hyaluronic Acid Capsule Biosynthesis Operon Is Regulated By Previously Unknown Upstream Elements, Marina Falaleeva, Oliwia W. Zurek, Robert L. Watkins, Robert W. Reed, Hadeel Ali, Paul Sumby, Jovanka M. Voyich, Natalia Korotkova

Molecular and Cellular Biochemistry Faculty Publications

The important human pathogen Streptococcus pyogenes (group A Streptococcus [GAS]) produces a hyaluronic acid (HA) capsule that plays critical roles in immune evasion. Previous studies showed that the hasABC operon encoding the capsule biosynthesis enzymes is under the control of a single promoter, P1, which is negatively regulated by the two-component regulatory system CovR/S. In this work, we characterize the sequence upstream of P1 and identify a novel regulatory region controlling transcription of the capsule biosynthesis operon in the M1 serotype strain MGAS2221. This region consists of a promoter, P2, which initiates transcription of a novel small RNA, HasS, an …

Huwe1 Is A Molecular Link Controlling Raf-1 Activity Supported By The Shoc2 Scaffold, Eun Ryoung Jang, Ping Shi, Jamal Bryant, Jing Chen, Vikas Dukhande, Matthew S. Gentry, Hyein Jang, Myoungkun Jeoung, Emilia Galperin

Molecular and Cellular Biochemistry Faculty Publications

Scaffold proteins play a critical role in controlling the activity of the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway. Shoc2 is a leucine-rich repeat scaffold protein that acts as a positive modulator of ERK1/2 signaling. However, the precise mechanism by which Shoc2 modulates the activity of the ERK1/2 pathway is unclear. Here we report the identification of the E3 ubiquitin ligase HUWE1 as a binding partner and regulator of Shoc2 function. HUWE1 mediates ubiquitination and, consequently, the levels of Shoc2. Additionally, we show that both Shoc2 and HUWE1 are necessary to control the levels and ubiquitination of the Shoc2 signaling partner, …

Repair Of O6-Methylguanine Adducts In Human Telomeric G-Quadruplex Dna By O6-Alkylguanine-Dna Alkyltransferase, Lance M. Hellman, Tyler J. Spear, Colton J. Koontz, Manana Melikishvili, Michael G. Fried

Molecular and Cellular Biochemistry Faculty Publications

O⁶-alkylguanine-DNA alkyltransferase (AGT) is a single-cycle DNA repair enzyme that removes pro-mutagenic O⁶-alkylguanine adducts from DNA. Its functions with short single-stranded and duplex substrates have been characterized, but its ability to act on other DNA structures remains poorly understood. Here, we examine the functions of this enzyme on O⁶-methylguanine (6mG) adducts in the four-stranded structure of the human telomeric G-quadruplex. On a folded 22-nt G-quadruplex substrate, binding saturated at 2 AGT:DNA, significantly less than the ~ 5 AGT:DNA found with linear single-stranded DNAs of similar length, and less than the value found with the …

An Intronic Picalm Polymorphism, Rs588076, Is Associated With Allelic Expression Of A Picalm Isoform, Ishita Parikh, Christopher Medway, Steven Younkin, David Fardo, Steven Estus

Physiology Faculty Publications

BACKGROUND: Although genome wide studies have associated single nucleotide polymorphisms (SNP)s near PICALM with Alzheimer's disease (AD), the mechanism underlying this association is unclear. PICALM is involved in clathrin-mediated endocytosis and modulates Aß clearance in vitro. Comparing allelic expression provides the means to detect cis-acting regulatory polymorphisms. Thus, we evaluated whether PICALM showed allele expression imbalance (AEI) and whether this imbalance was associated with the AD-associated polymorphism, rs3851179.

RESULTS: We measured PICALM allelic expression in 42 human brain samples by using next-generation sequencing. Overall, PICALM demonstrated equal allelic expression with no detectable influence by rs3851179. A single sample demonstrated …

Neuroinflammation And Neurologic Deficits In Diabetes Linked To Brain Accumulation Of Amylin, Sarah Srodulski, Savita Sharma, Adam B. Bachstetter, Jennifer M. Brelsfoard, Conrado Pascual, Xinmin Simon Xie, Kathryn E. Saatman, Linda J. Van Eldik, Florin Despa

Pharmacology and Nutritional Sciences Faculty Publications

BACKGROUND: We recently found that brain tissue from patients with type-2 diabetes (T2D) and cognitive impairment contains deposits of amylin, an amyloidogenic hormone synthesized and co-secreted with insulin by pancreatic β-cells. Amylin deposition is promoted by chronic hypersecretion of amylin (hyperamylinemia), which is common in humans with obesity or pre-diabetic insulin resistance. Human amylin oligomerizes quickly when oversecreted, which is toxic, induces inflammation in pancreatic islets and contributes to the development of T2D. Here, we tested the hypothesis that accumulation of oligomerized amylin affects brain function.

METHODS: In contrast to amylin from humans, rodent amylin is neither amyloidogenic nor cytotoxic. …

Paramyxovirus Glycoprotein Incorporation, Assembly And Budding: A Three Way Dance For Infectious Particle Production, Farah El Najjar, Anthony P. Schmitt, Rebecca Ellis Dutch

Molecular and Cellular Biochemistry Faculty Publications

Paramyxoviruses are a family of negative sense RNA viruses whose members cause serious diseases in humans, such as measles virus, mumps virus and respiratory syncytial virus; and in animals, such as Newcastle disease virus and rinderpest virus. Paramyxovirus particles form by assembly of the viral matrix protein, the ribonucleoprotein complex and the surface glycoproteins at the plasma membrane of infected cells and subsequent viral budding. Two major glycoproteins expressed on the viral envelope, the attachment protein and the fusion protein, promote attachment of the virus to host cells and subsequent virus-cell membrane fusion. Incorporation of the surface glycoproteins into infectious …

Cardioprotection By Controlling Hyperamylinemia In A "Humanized" Diabetic Rat Model, Sanda Despa, Savita Sharma, Todd R. Harris, Hua Dong, Ning Li, Nipavan Chiamvimonvat, Heinrich Taegtmeyer, Kenneth B. Margulies, Bruce D. Hammock, Florin Despa

Pharmacology and Nutritional Sciences Faculty Publications

BACKGROUND: Chronic hypersecretion of the pancreatic hormone amylin is common in humans with obesity or prediabetic insulin resistance and induces amylin aggregation and proteotoxicity in the pancreas. We recently showed that hyperamylinemia also affects the cardiovascular system. Here, we investigated whether amylin aggregates interact directly with cardiac myocytes and whether controlling hyperamylinemia protects the heart.

METHODS AND RESULTS: By Western blot, we found abundant amylin aggregates in lysates of cardiac myocytes from obese patients, but not in controls. Aggregated amylin was elevated in failing hearts, suggesting a role in myocyte injury. Using rats overexpressing human amylin in the pancreas (HIP …

Neutral Sphingomyelinase-3 Mediates Tnf-Stimulated Oxidant Activity In Skeletal Muscle, Jennifer S. Moylan, Jeffrey D. Smith, Erin M. Wolf Horrell, Julie B. Mclean, Gergana M. Deevska, Mark R. Bonnell, Mariana N. Nikolova‑Karakashian, Michael B. Reid

Physiology Faculty Publications

AIMS: Sphingolipid and oxidant signaling affect glucose uptake, atrophy, and force production of skeletal muscle similarly and both are stimulated by tumor necrosis factor (TNF), suggesting a connection between systems. Sphingolipid signaling is initiated by neutral sphingomyelinase (nSMase), a family of agonist-activated effector enzymes. Northern blot analyses suggest that nSMase3 may be a striated muscle-specific nSMase. The present study tested the hypothesis that nSMase3 protein is expressed in skeletal muscle and functions to regulate TNF-stimulated oxidant production.

RESULTS: We demonstrate constitutive nSMase activity in skeletal muscles of healthy mice and humans and in differentiated C2C12 myotubes. nSMase3 ( …

Cell Type-Dependent Rna Recombination Frequency In The Japanese Encephalitis Virus, Wei-Wei Chiang, Chingkai Chuang, Mei Chao, Wei-June Chen

Plant Pathology Faculty Publications

Japanese encephalitis virus (JEV) is one of approximately 70 flaviviruses, frequently causing symptoms involving the central nervous system. Mutations of its genomic RNA frequently occur during viral replication, which is believed to be a force contributing to viral evolution. Nevertheless, accumulating evidences show that some JEV strains may have actually arisen from RNA recombination between genetically different populations of the virus. We have demonstrated that RNA recombination in JEV occurs unequally in different cell types. In the present study, viral RNA fragments transfected into as well as viral RNAs synthesized in mosquito cells were shown not to be stable, especially …

Self-Reported Head Injury And Risk Of Late-Life Impairment And Ad Pathology In An Ad Center Cohort, Erin L. Abner, Peter T. Nelson, Frederick A. Schmitt, Steven R. Browning, David W. Fardo, Lijie Wan, Gregory A. Jicha, Gregory E. Cooper, Charles D. Smith, Allison M. Caban-Holt, Linda J. Van Eldik, Richard J. Kryscio

Sanders-Brown Center on Aging Faculty Publications

Aims: To evaluate the relationship between self-reported head injury and cognitive impairment, dementia, mortality, and Alzheimer's disease (AD)-type pathological changes. Methods: Clinical and neuropathological data from participants enrolled in a longitudinal study of aging and cognition (n = 649) were analyzed to assess the chronic effects of self-reported head injury. Results: The effect of self-reported head injury on the clinical state depended on the age at assessment: for a 1-year increase in age, the OR for the transition to clinical mild cognitive impairment (MCI) at the next visit for participants with a history of head injury was 1.21 and 1.34 …

Arrhythmogenic Calmodulin Mutations Disrupt Intracellular Cardiomyocyte Ca2+ Regulation By Distinct Mechanisms, Guo Yin, Faisal Hassan, Ayman R. Haroun, Lisa L. Murphy, Lia Crotti, Peter J. Schwartz, Alfred L. George, Jonathan Satin

Physiology Faculty Publications

BACKGROUND: Calmodulin (CaM) mutations have been identified recently in subjects with congenital long QT syndrome (LQTS) or catecholaminergic polymorphic ventricular tachycardia (CPVT), but the mechanisms responsible for these divergent arrhythmia-susceptibility syndromes in this context are unknown. We tested the hypothesis that LQTS-associated CaM mutants disrupt Ca²⁺ homeostasis in developing cardiomyocytes possibly by affecting either late Na current or Ca²⁺-dependent inactivation of L-type Ca²⁺ current.

METHODS AND RESULTS: We coexpressed CaM mutants with the human cardiac Na channel (Na_V1.5) in tsA201 cells, and we used mammalian fetal ventricular cardiomyocytes to investigate LQTS- and CPVT-associated CaM …

The Human Metapneumovirus Small Hydrophobic Protein Has Properties Consistent With Those Of A Viroporin And Can Modulate Viral Fusogenic Activity, Cyril Masante, Farah El Najjar, Andres Chang, Angela Jones, Carole L. Moncman, Rebecca Ellis Dutch

Molecular and Cellular Biochemistry Faculty Publications

Human metapneumovirus (HMPV) encodes three glycoproteins: the glycoprotein, which plays a role in glycosaminoglycan binding, the fusion (F) protein, which is necessary and sufficient for both viral binding to the target cell and fusion between the cellular plasma membrane and the viral membrane, and the small hydrophobic (SH) protein, whose function is unclear. The SH protein of the closely related respiratory syncytial virus has been suggested to function as a viroporin, as it forms oligomeric structures consistent with a pore and alters membrane permeability. Our analysis indicates that both the full-length HMPV SH protein and the isolated SH protein transmembrane …

Control Of Cellular Motility By Neuropilin-Mediated Physical Interactions, Xiaobo Li, Matthew W. Parker, Craig W. Vander Kooi

Molecular and Cellular Biochemistry Faculty Publications

The neuropilin (Nrp) family consists of multifunctional cell surface receptors with critical roles in a number of different cell and tissue types. A core aspect of Nrp function is in ligand-dependent cellular migration, where it controls the multistep process of cellular motility through integration of ligand binding and receptor signaling. At a molecular level, the role of Nrp in migration is intimately connected to the control of adhesive interactions and cytoskeletal reorganization. Here, we review the physiological role of Nrp in cellular adhesion and motility in the cardiovascular and nervous systems. We also discuss the emerging pathological role of Nrp …

Sudemycin E Influences Alternative Splicing And Changes Chromatin Modifications, Paolo Convertini, Manli Shen, Philip M. Potter, Gustavo Palacios, Chandraiah Lagisetti, Pierre De La Grange, Craig Horbinski, Yvonne N. Fondufe-Mittendorf, Thomas R. Webb, Stefan Stamm

Molecular and Cellular Biochemistry Faculty Publications

Sudemycin E is an analog of the pre-messenger RNA splicing modulator FR901464 and its derivative spliceostatin A. Sudemycin E causes the death of cancer cells through an unknown mechanism. We found that similar to spliceostatin A, sudemycin E binds to the U2 small nuclear ribonucleoprotein (snRNP) component SF3B1. Native chromatin immunoprecipitations showed that U2 snRNPs physically interact with nucleosomes. Sudemycin E induces a dissociation of the U2 snRNPs and decreases their interaction with nucleosomes. To determine the effect on gene expression, we performed genome-wide array analysis. Sudemycin E first causes a rapid change in alternative pre-messenger RNA splicing, which is …

The Rak/Frk Tyrosine Kinase Associates With And Internalizes The Epidermal Growth Factor Receptor, Ling Jin, Rolf J. Craven

Pharmacology and Nutritional Sciences Faculty Publications

Src is the founding member of a diverse family of intracellular tyrosine kinases, and Src has a key role in promoting cancer growth, in part, through its association with receptor tyrosine kinases. However, some Src-related proteins have widely divergent physiological roles, and these proteins include the Rak/Frk tyrosine kinase (Frk stands for Fyn-related kinase), which inhibits cancer cell growth and suppresses tumorigenesis. Rak/Frk phosphorylates and stabilizes the Pten tumor suppressor, protecting it from degradation, and Rak/Frk associates with the retinoblastoma (Rb) tumor suppressor. However, the role of Rak/Frk in receptor-mediated signaling is largely unknown. Here, we demonstrate that Rak/Frk associates …

Redox Pioneer: Professor Joe M. Mccord, David M. Schnell, Daret K. St Clair

Graduate Center for Nutritional Sciences Faculty Publications

Dr. Joe McCord (Ph.D. 1970) is recognized here as a Redox Pioneer because he has published at least three articles on antioxidant/redox biology as first/last author that have been cited over 1000 times and has published at least 37 articles each cited over 100 times. Dr. McCord is known for the monumental discovery of the antioxidant superoxide dismutase (SOD) while a graduate student under fellow redox pioneer Irwin Fridovich and demonstrating its necessity to aerobic life. Beyond this, McCord's career is distinguished for bridging the gap from basic science to clinical relevance by showing the application of SOD and superoxide …