Biochemistry, Biophysics, and Structural Biology Commons^™

A Xenopus Oocyte Model System To Study Action Potentials, Aaron Corbin-Leftwich, Hannah E Small, Helen H Robinson, Carlos A. Villalba-Galea, Linda M Boland

School of Pharmacy Faculty Articles

Action potentials (APs) are the functional units of fast electrical signaling in excitable cells. The upstroke and downstroke of an AP is generated by the competing and asynchronous action of Na+- and K+-selective voltage-gated conductances. Although a mixture of voltage-gated channels has been long recognized to contribute to the generation and temporal characteristics of the AP, understanding how each of these proteins function and are regulated during electrical signaling remains the subject of intense research. AP properties vary among different cellular types because of the expression diversity, subcellular location, and modulation of ion channels. These complexities, in addition to the …

Nrh:Quinone Oxidoreductase 2 (Nqo2) And Glutaminase (Gls) Both Play A Role In Large Extracellular Vesicles (Lev) Formation In Preclinical Lncap-C4-2b Prostate Cancer Model Of Progressive Metastasis, Thambi Dorai, Ankeeta Shah, Faith Summers, Rajamma Mathew, Jing Huang, Tze-Chen Hsieh, Joseph M. Wu

NYMC Faculty Publications

In the course of studies aimed at the role of oxidative stress in the development of metastatic potential in the LNCaP-C4-2B prostate cancer progression model system, we found a relative decrease in the level of expression of the cytoplasmic nicotinamide riboside: quinone oxidoreductase (NQO2) and an increase in the oxidative stress in C4-2B cells compared to that in LNCaP or its derivatives C4 and C4-2. It was also found that C4-2B cells specifically shed large extracellular vesicles (LEVs) suggesting that these LEVs and their cargo could participate in the establishment of the osseous metastases. The level of expression of caveolin-1 …

Direct Quantification Of Deubiquitinating Enzyme Activity In Single Intact Cells, Nora Safabakhsh

LSU Doctoral Dissertations

Challenges in drug efficacy occur during the treatment of most types of cancer due to the heterogeneity of the tumor microenvironment. This has led to the development of personalized medicine. Due to the clinical success of the proteasome inhibitors Bortezomib and Carfilzomib in treatment of multiple myeloma, interest has shifted towards molecularly-targeted chemotherapeutics for ubiquitin-proteasome system (UPS). Deubiquitinating enzymes (DUBs) are an essential part of this pathway which have been found to promote Bortezomib resistance in multiple myeloma patients. Unfortunately, there is a lack of specific, high throughput biochemical assays to characterize DUB activity in patient samples before and after …

Fars2 Mutations Presenting With Pure Spastic Paraplegia And Lesions Of The Dentate Nuclei, Supreet K. Sahai, Rebecca E. Steiner, Margaret G. Au, John M. Graham, Norikio Salamon, Michael Ibba, Tyler M. Pierson

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Mutations in FARS2, the gene encoding the mitochondrial phenylalanine‐tRNA synthetase (mtPheRS), have been linked to a range of phenotypes including epileptic encephalopathy, developmental delay, and motor dysfunction. We report a 9‐year‐old boy with novel compound heterozygous variants of FARS2, presenting with a pure spastic paraplegia syndrome associated with bilateral signal abnormalities in the dentate nuclei. Exome sequencing identified a paternal nonsense variant (Q216X) lacking the catalytic core and anticodon‐binding regions, and a maternal missense variant (P136H) possessing partial enzymatic activity. This case confirms and expands the phenotype related to FARS mutations with regards to clinical presentation and neuroimaging findings.

Inhibition Of Ribosome Biogenesis Through Genetic And Chemical Approaches, Leonid Anikin

Graduate School of Biomedical Sciences Theses and Dissertations

In order to maintain the ability to generate proteins, proliferating cells must continuously generate ribosomes, designating up to 80% of their energy to ribosome biogenesis (RBG). RBG involves transcription of rDNA by RNA polymerases I (Pol I) and III (Pol III), expression of approximately 80 ribosomal proteins, and assembly of these components in a process referred to as ribosome maturation. During maturation, the Pol I transcribed 47S pre-rRNA undergoes a number of processing events, while simultaneously interacting with processing factors and ribosomal proteins that drive pre-ribosome assembly. Inhibition of RBG has become one of the pursued targets for cancer therapy …

The N-Terminal Methyltransferase Homologs Nrmt1 And Nrmt2 Exhibit Novel Regulation Of Activity Through Heterotrimer Formation., Jon David Faughn

Electronic Theses and Dissertations

Protein, DNA, and RNA methyltransferases have an ever-expanding list of novel substrates and catalytic activities. Even within families and between homologs, it is becoming clear the intricacies of methyltransferase specificity and regulation are far more diverse than originally thought. In addition to specific substrates and distinct methylation levels, methyltransferase activity can be altered through formation of complexes with close homologs. This work involves the N-terminal methyltransferase homologs NRMT1 and NRMT2. NRMT1 is a ubiquitously expressed distributive trimethylase. NRMT2 is a monomethylase expressed at low levels and in a tissue-specific manner. They are both nuclear methyltransferases with overlapping target consensus sequences …

Fluorescently Labeled Sirnas And Their Theranostic Applications In Cancer Gene Therapy, Stephen David Kozuch

Seton Hall University Dissertations and Theses (ETDs)

Gene therapy has emerged as a promising precision nano-medicine strategy in the treatment of numerous diseases including cancer. At the forefront of its utility are the applications of short-interfering RNA (siRNA), that silence oncogenic mRNA expression leading to cancer cell death through the RNA interference (RNAi) pathway. Despite the therapeutic potential, siRNAs are limited by poor pharmacological properties, which has hindered their translation into the clinic. Recent studies, however, have highlighted the applications of modified siRNAs, including the use of fluorescent probes and siRNA nanostructures in cancer detection and treatment. The siRNAs reported in this thesis are designed to target …

Transcriptomics Of Learning, Pablo Iturralde

Theses

Learning is a basic and important component of behavior yet we have very little empirical information about the interaction between mechanisms of learning and evolution. In our work, we are testing hypotheses about the neurogenetic mechanisms through which animal learning abilities evolve. We are able to test this directly by using experimentally evolved populations of flies, which differ in learning ability. These populations were previously evolved within the lab by creating worlds with different patterns of change following theoretically predicted effects on which enhanced learning will evolve. How has evolution acted to modulate genes and gene expression in the brain …

Codon Usage Revisited: Lack Of Correlation Between Codon Usage And The Number Of Trna Genes In Enterobacteria, Joaquín Rojas, Gabriel Castillo, Lorenzo Eugenio Leiva, Sara Elgamal, Omar Orellana, Michael Ibba, Assaf Katz

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

It is widely believed that if a high number of genes are found for any tRNA in a rapidly replicating bacteria, then the cytoplasmic levels of that tRNA will be high and an open reading frame containing a higher frequency of the complementary codon will be translated faster. This idea is based on correlations between the number of tRNA genes, tRNA concentration and the frequency of codon usage observed in a limited number of strains as well as from the fact that artificially changing the number of tRNA genes alters translation efficiency and consequently the amount of properly folded protein …

Abcg5 And Abcg8: More Than A Defense Against Xenosterols, Shailendra B. Patel, Gregory A. Graf, Ryan E. Temel

Pharmaceutical Sciences Faculty Publications

The elucidation of the molecular basis of the rare disease, sitosterolemia, has revolutionized our mechanistic understanding of how dietary sterols are excreted and how cholesterol is eliminated from the body. Two proteins, ABCG5 and ABCG8, encoded by the sitosterolemia locus, work as obligate dimers to pump sterols out of hepatocytes and enterocytes. ABCG5/ABCG8 are key in regulating whole-body sterol trafficking, by eliminating sterols via the biliary tree as well as the intestinal tract. Importantly, these transporters keep xenosterols from accumulating in the body. The sitosterolemia locus has been genetically associated with lipid levels and downstream atherosclerotic disease, as well as …

The Regulation Of Dna Methylation In Mammalian Development And Cancer, Nicolas Veland

Dissertations and Theses (Open Access)

DNA methylation is an essential epigenetic modification in mammals, as it plays important regulatory roles in multiple biological processes, such as gene transcription, maintenance of chromosomal structure and genomic stability, genomic imprinting, retrotransposon silencing, and X-chromosome inactivation. Dysregulation of DNA methylation is associated with various human diseases. For example, cancer cells usually show global hypomethylation and regional hypermenthylation, which have been implicated in genomic instability and tumor suppressor silencing, respectively. Although great progress has been made in elucidating the biological functions of DNA methylation over the last several decades, how DNA methylation patterns and levels are regulated and dysregulated is …

A Cytotoxic Evaluation Of A Chalcone Derivative Library On A549 Cells, Mary Elaine Kuo

Undergraduate Theses

Chalcones, a precursor to flavonoids, are chemical compounds found naturally in plants. The chalcones’ structure consists of a ketone bridge attached to two aromatic rings. Varying substituents on the aromatic rings allow for different affects, including anti-cancer properties. As a Michael acceptor, chalcones interact with pathways that cause inhibition of the initiation, promotion, and progression of cancer tumors. We have screened 32 compounds for growth inhibition in lung cells that vary the flexibility and confirmation of the 3 carbon bridge between the two aromatic rings as well as the effects of electronic modifications to the aromatic ring. We have found …

Role Of Protein Charge Density On Hepatitis B Virus Capsid Formation, Xinyu Sun, Dong Li, Zhaoshuai Wang, Panchao Yin, Rundong Hu, Rundong Hu, Hui Li, Qiao Liu, Yunyi Gao, Baiping Ren, Jie Zheng, Yinan Wei, Tianbo Liu

Chemistry Faculty Publications

The role of electrostatic interactions in the viral capsid assembly process was studied by comparing the assembly process of a truncated hepatitis B virus capsid protein Cp149 with its mutant protein D2N/D4N, which has the same conformational structure but four fewer charges per dimer. The capsid protein self-assembly was investigated under a wide range of protein surface charge densities by changing the protein concentration, buffer pH, and solution ionic strength. Lowering the protein charge density favored the capsid formation. However, lowering charge beyond a certain point resulted in capsid aggregation and precipitation. Interestingly, both the wild-type and D2N/D4N mutant displayed …

Transmembrane Domains Of Highly Pathogenic Viral Fusion Proteins Exhibit Trimeric Association In Vitro, Stacy R. Webb, Stacy E. Smith, Michael G. Fried, Rebecca Ellis Dutch

Molecular and Cellular Biochemistry Faculty Publications

Enveloped viruses require viral fusion proteins to promote fusion of the viral envelope with a target cell membrane. To drive fusion, these proteins undergo large conformational changes that must occur at the right place and at the right time. Understanding the elements which control the stability of the prefusion state and the initiation of conformational changes is key to understanding the function of these important proteins. The construction of mutations in the fusion protein transmembrane domains (TMDs) or the replacement of these domains with lipid anchors has implicated the TMD in the fusion process. However, the structural and molecular details …

Ef-P Post-Translational Modification Has Variable Impact On Polyproline Translation In Bacillus Subtilis, Anne Witzky, Katherine R. Hummels, Rodney Tollerson Ii, Andrei Rajkovic, Lisa A. Jones, Daniel B. Kearns, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Elongation factor P (EF-P) is a ubiquitous translation factor that facilitates translation of polyproline motifs. In order to perform this function, EF-P generally requires posttranslational modification (PTM) on a conserved residue. Although the position of the modification is highly conserved, the structure can vary widely between organisms. In Bacillus subtilis, EF-P is modified at Lys³² with a 5-aminopentanol moiety. Here, we use a forward genetic screen to identify genes involved in 5-aminopentanolylation. Tandem mass spectrometry analysis of the PTM mutant strains indicated that ynbB, gsaB, and ymfI are required for modification and that yaaO, yfkA, and …

Cross Talk Between Serum Kisspeptin-Leptin During Assisted Reproduction Techniques, Rehana Rehman, Zehra Jamil, Aqsa Khalid, Syeda Sadia Fatima

Department of Biological & Biomedical Sciences

Background & Objective: Leptin facilitates onset of puberty by impact on hypothalamic Kisspeptin, gonadotropin releasing hormone, follicle stimulating and luteinizing hormone. The link of peripheral Leptin-Kisspeptin in regulating the ovarian and endometrial tissue in relation to adiposity is unknown. Therefore, we wanted to identify Kisspeptin-Leptin association with body mass index (BMI) and success of assisted reproductive treatments (ART) in infertile females.
Methods: A cross sectional study was carried from August 2014 till May 2016 after receiving ethical approval at Australian Concept Infertility Medical Centre, and Aga Khan University. The study group comprised of females with an age range …

Increased Liver Tumor Formation In Neutral Sphingomyelinase-2-Deficient Mice, Liansheng Zhong, Ji Na Kong, Michael B. Dinkins, Silvia Leanhart, Zhihui Zhu, Stefka D. Spassieva, Haiyan Qin, Hsuan-Pei Lin, Ahmed Elsherbini, Rebecca Wang, Xue Jiang, Mariana N. Nikolova‑Karakashian, Guanghu Wang, Erhard Bieberich

Physiology Faculty Publications

Sphingolipids are key signaling lipids in cancer. Genome-wide studies have identified neutral SMase-2 (nSMase2), an enzyme generating ceramide from SM, as a potential repressor for hepatocellular carcinoma. However, little is known about the sphingolipids regulated by nSMase2 and their roles in liver tumor development. We discovered growth of spontaneous liver tumors in 27.3% (9 of 33) of aged male nSMase2-deficient (fro/fro) mice. Lipidomics analysis showed a marked increase of SM in the tumor. Unexpectedly, tumor tissues presented with more than a 7-fold increase of C₁₆-ceramide, concurrent with upregulation of ceramide synthase 5. The fro/fro liver tumor, …

A Chimeric Nucleobase - Phenylazo Derivative As An Intrinsic Nucleobase Quencher, Gyeongsu Park, Timothy Martin-Chan, Amer El Samm, Robert H.E. Hudson

Western Research Forum

Molecular beacons are important bioanalytical probes which are most often

constructed from a single-stranded oligonucleotide which has been labeled at

opposite termini with a fluorophore and a quencher. When the fluorophore and

quencher are in close proximity, no fluorescence is observed due to FRET

(Fluorescence Resonance Energy Transfer). DABCYL (4-dimethylaminoazobenzene-

4'-carboxylic acid) has been used as a quencher in the molecular beacon to absorbs

excitation energy from a fluorophore and to dissipate the energy as heat. However,

DABCYL is unable to form a base-pair and is conventionally placed as an overhanging

residue. This produces a derivative wherein the chromophore has …

Studies Of Amino Acid Mutations In Drug Resistance Of The Smo Protein, Eunice Wintona

UNO Student Research and Creative Activity Fair

Smoothened receptor (SMO) is a protein that in humans, is encoded by the SMO gene. A systemic mutation in its binding pocket helps predict the sensitivity of mutant proteins to different drugs. Known as a GPCR-like receptor, it is a component of the hedgehog signaling pathway; a pathway involved in body patterning and the regulation of adult stem cells. An uncontrolled or inappropriate activation of the Hedgehog pathway drives tumor progression in cancers and a number of birth defects. To achieve these goals, the molecular modeling software MOE was used to build small molecules and drug molecules like Vismodegib and …

Insulin-Degrading Enzyme Is Not Secreted From Cultured Cells, Eun Suk Song, David W. Rodgers, Louis Hersh

Molecular and Cellular Biochemistry Faculty Publications

Insulin-degrading enzyme (IDE) functions in the catabolism of bioactive peptides. Established roles include degrading insulin and the amyloid beta peptide (Aβ), linking it to diabetes and Alzheimer’s disease. IDE is primarily located in the cytosol, and a longstanding question is how it gains access to its peptide substrates. Reports suggest that IDE secreted by an unconventional pathway participates in extracellular hydrolysis of insulin and Aβ. We find that IDE release from cultured HEK-293 or BV-2 cells represents only ~1% of total cellular IDE, far less than has been reported previously. Importantly, lactate dehydrogenase (LDH) and other cytosolic enzymes are released …

Inactivation Of Myeloma Cancer Cells By Helium And Argon Plasma Jets: The Effect Comparison And The Key Reactive Species, Zeyu Chen, Qingjie Cui, Chen Chen, Dehui Xu, Dingxin Liu, H. L. Chen, Michael G. Kong

Bioelectrics Publications

In plasma cancer therapy, the inactivation of cancer cells under plasma treatment is closely related to the reactive oxygen and nitrogen species (RONS) induced by plasmas. Quantitative study on the plasma-induced RONS that related to cancer cells apoptosis is critical for advancing the research of plasma cancer therapy. In this paper, the effects of several reactive species on the inactivation of LP-1 myeloma cancer cells are comparatively studied with variable working gas composition, surrounding gas composition, and discharge power. The results show that helium plasma jet has a higher cell inactivation efficiency than argon plasma jet under the same discharge …

Regulation Of Kv2.1 Channel Inactivation By Phosphatidylinositol 4,5-Bisphosphate., Mayra Delgado-Ramírez, José J De Jesús-Pérez, Iván A Aréchiga-Figueroa, Jorge Arreola, Scott K Adney, Carlos A. Villalba-Galea, Diomedes E Logothetis, Aldo A Rodríguez-Menchaca

School of Pharmacy Faculty Articles

Phosphatidylinositol 4,5-bisphosphate (PIP2) is a membrane phospholipid that regulates the function of multiple ion channels, including some members of the voltage-gated potassium (Kv) channel superfamily. The PIP2 sensitivity of Kv channels is well established for all five members of the Kv7 family and for Kv1.2 channels; however, regulation of other Kv channels by PIP2 remains unclear. Here, we investigate the effects of PIP2 on Kv2.1 channels by applying exogenous PIP2 to the cytoplasmic face of excised membrane patches, activating muscarinic receptors (M1R), or depleting endogenous PIP2 using a rapamycin-translocated 5-phosphatase (FKBP-Inp54p). Exogenous PIP2 rescued Kv2.1 channels from rundown and partially …

Dynamic Cycling Of T-Snare Acylation Regulates Platelet Exocytosis, Jinchao Zhang, Yunjie Huang, Jing Chen, Haining Zhu, Sidney W. Whiteheart

Molecular and Cellular Biochemistry Faculty Publications

Platelets regulate vascular integrity by secreting a host of molecules that promote hemostasis and its sequelae. Given the importance of platelet exocytosis, it is critical to understand how it is controlled. The t-SNAREs, SNAP-23 and syntaxin-11, lack classical transmembrane domains (TMDs), yet both are associated with platelet membranes and redistributed into cholesterol-dependent lipid rafts when platelets are activated. Using metabolic labeling and hydroxylamine (HA)/HCl treatment, we showed that both contain thioester-linked acyl groups. Mass spectrometry mapping further showed that syntaxin-11 was modified on cysteine 275, 279, 280, 282, 283, and 285, and SNAP-23 was modified on cysteine 79, 80, 83, …

Novel Function Of Ceramide For Regulation Of Mitochondrial Atp Release In Astrocytes, Ji-Na Kong, Zhihui Zhu, Yutaka Itokazu, Guanghu Wang, Michael B. Dinkins, Liansheng Zhong, Hsuan-Pei Lin, Ahmed Elsherbini, Silvia Leanhart, Xue Jiang, Haiyan Qin, Wenbo Zhi, Stefka D. Spassieva, Erhard Bieberich

Physiology Faculty Publications

We reported that amyloid β peptide (Aβ₄₂) activated neutral SMase 2 (nSMase2), thereby increasing the concentration of the sphingolipid ceramide in astrocytes. Here, we show that Aβ₄₂ induced mitochondrial fragmentation in wild-type astrocytes, but not in nSMase2-deficient cells or astrocytes treated with fumonisin B1 (FB1), an inhibitor of ceramide synthases. Unexpectedly, ceramide depletion was concurrent with rapid movements of mitochondria, indicating an unknown function of ceramide for mitochondria. Using immunocytochemistry and super-resolution microscopy, we detected ceramide-enriched and mitochondria-associated membranes (CEMAMs) that were codistributed with microtubules. Interaction of ceramide with tubulin was confirmed by cross-linking to N-[9-(3-pent-4-ynyl-3-H-diazirine-3-yl)-nonanoyl]-D-erythro-sphingosine …

Modulation Of Electron Transport By Metformin In Cardiac Protection: Role Of Complex I, Ahmed Abdul Hussein Mohsin

Theses and Dissertations

Modulation of mitochondrial complex I during reperfusion reduces cardiac injury. Complex I exists in two structural states: active (A) and deactive (D) with transition from A→D during ischemia. Reperfusion reactivates D→A with an increase in ROS production. Metformin preserves the D-Form. Our aim was to study the contribution of maintenance of deactivation of complex I during early reperfusion by metformin to protect against ischemia reperfusion injury. Our results showed that metformin decreased H9c2 cardiomyoblast apoptosis and total cell death following simulated ischemia for six hours followed by reoxygenation for twenty four hours compared to untreated cells. Reactive oxygen species (ROS) …

Characterization Of Tetraethyl Orthosilicate-Based Dynamic Hydrogels For Use As Reversible 3-D Cell Culture Matrices, Krisitan Stipe

Graduate Student Theses, Dissertations, & Professional Papers

No abstract provided.

In Vitro Genetic Code Expansion And Selected Applications, Emil S. Iqbal

Theses and Dissertations

The ability of incorporation non-canonical amino acids (ncAAs) using translation offers researchers the ability of extend the functionality of proteins and peptides for many applications including synthetic biology, biophysical and structural studies, and discovery of novel ligands. Here we describe the three projects where the addition of ncAAs to in vitro translation systems creates useful chemical biology techniques. In the first, a fluorinated histidine derivative is used to create a novel affinity tag that allows for the selective purification of peptides from a complex mixture of proteins. In the second, the high promiscuity of an editing-deficient valine-tRNA synthetase (ValRS T222P) …

Tfpiα Interacts With Fva And Fxa To Inhibit Prothrombinase During The Initiation Of Coagulation, Jeremy P. Wood, Helle H. Petersen, Bingke Yu, Xiaoai Wu, Ida Hilden, Alan E. Mast

Gill Heart & Vascular Institute Faculty Publications

Tissue factor pathway inhibitor α (TFPIα) inhibits prothrombinase, the thrombin-generating complex of factor Xa (FXa) and factor Va (FVa), during the initiation of coagulation. This inhibition requires binding of a conserved basic region within TFPIα to a conserved acidic region in FXa-activated and platelet-released FVa. In this study, the contribution of interactions between TFPIα and the FXa active site and FVa heavy chain to prothrombinase inhibition were examined to further define the inhibitory biochemistry. Removal of FXa active site binding by mutation or by deletion of the second Kunitz domain (K2) of TFPIα produced 17- or 34-fold weaker prothrombinase inhibition, …

9-Aminoacridine Inhibits Ribosome Biogenesis And Synergizes With Cytotoxic Drugs To Induce Selective Killing Of P53-Deficient Cells, Leonid Anikin, Dimitri G Pestov

Rowan-Virtua School of Osteopathic Medicine Departmental Research

Common cancer treatments target rapidly dividing cells and do not discriminate between cancer and normal host cells. One approach to mitigating negative side‐effects of cancer treatment is to temporarily arrest cell cycle progression and thus protect normal cells during cytotoxic treatments, a concept called cyclotherapy. We recently proposed that transient inhibition of post‐transcriptional steps of ribosome biogenesis (RBG) can be used to selectively arrest p53‐positive host cells and not p53‐null cancer cells. In this study, we investigated whether cytoprotective RBG inhibition can be achieved through small molecule treatment.

Structural And Functional Insights Into The Role Of Bamd And Bame Within The Β-Barrel Assembly Machinery In Neisseria Gonorrhoeae, Aleksandra E. Sikora, Igor H. Wierzbicki, Ryszard A. Zielke, Rachael F. Ryner, Konstantin V. Korotkov, Susan K. Buchanan, Nicholas Noinaj

Molecular and Cellular Biochemistry Faculty Publications

The β-barrel assembly machinery (BAM) is a conserved multicomponent protein complex responsible for the biogenesis of β-barrel outer membrane proteins (OMPs) in Gram-negative bacteria. Given its role in the production of OMPs for survival and pathogenesis, BAM represents an attractive target for the development of therapeutic interventions, including drugs and vaccines against multidrug-resistant bacteria such as Neisseria gonorrhoeae. The first structure of BamA, the central component of BAM, was from N. gonorrhoeae, the etiological agent of the sexually transmitted disease gonorrhea. To aid in pharmaceutical targeting of BAM, we expanded our studies to BamD and BamE within …