Biochemistry Commons^™

Defining The Role Of Phosphorylation And Dephosphorylation In The Regulation Of Gap Junction Proteins, Hanjun Li

Theses & Dissertations

Gap junctions are intercellular channels that permit the free passage of ions, small metabolites, and signaling molecules between neighboring cells. In the diseased human heart, altered ventricular gap junction organization and connexin expression (i.e., remodeling) are key contributors to rhythm disturbances and contractile dysfunction. Connexin43 (Cx43) is the dominant gap junction protein isoform in the ventricle which is under tight regulation by serine/tyrosine phosphorylation. Phosphorylation and dephosphorylation regulate many aspects of Cx43 function including trafficking, assembly and disassembly, electrical and metabolic coupling at the plaque, as well as to modulate the interaction with other proteins.

Serine phosphorylation has long been …

Regulation Of Alteration/Deficiency In Activation 3 (Ada3) By Acetylation And Its Role In Cell Cycle Regulation And Oncogenesis, Shashank Srivastava

Theses & Dissertations

The ADA3 (Alteration/Deficiency in Activation 3) protein is a transcriptional adaptor protein that was initially discovered as a component of several HAT (Histone Acetyltransferase) complexes, the enzyme complex responsible for histone acetylation, which is a prerequisite for transcription. Earlier the studies from Dr. Band’s laboratory and that of others’ have deciphered a crucial role of ADA3 in cell cycle regulation (both through G₁/S and G₂/M phase transitions) and in maintaining the genomic stability.

While our laboratory investigated the mechanism behind the role of ADA3 in G₁/S transition, the same remained unknown for G_{2 …}

Mitogen And Morphogen Signaling Dysregulation: Pathophysiological Influence In Pancreatic Cancer And Alzheimer’S Disease, Eric Cruz

Theses & Dissertations

Although the etiology of a particular disease will vary, there are genetic and epigenetic bottlenecks that frequently converge resulting in dysregulation of mitogenic and morphogenetic signaling. This propensity is acutely experienced in malignancy and neurodegenerative disease.

Here, we have first investigated the role of dysregulated signaling in the context of pancreatic cancer (PC). Morphogenetic signaling has been regarded as a pleiotropic pathway with the potential to promote and inhibit metastatic features. Our investigation of bone morphogenetic protein 2 (BMP-2), an archetypical member of the BMP superfamily, has revealed the presence of extracellular, intracellular, and long non-coding RNA products. Our findings …

Dna Polymerase Zeta-Dependent Mutagenesis: Molecular Specificity, Extent Of Error-Prone Synthesis, And The Role Of Dntp Pools, Olga V. Kochenova

Theses & Dissertations

Despite multiple DNA repair pathways, DNA lesions can escape repair and compromise normal chromosomal replication, leading to genome instability. Cells utilize specialized low-fidelity Translesion Synthesis (TLS) DNA polymerases to bypass lesions and rescue arrested replication forks. TLS is a highly conserved two-step process that involves insertion of a nucleotide opposite a lesion and extension of the resulting aberrant primer terminus. The first step can be performed by both replicative and TLS DNA polymerases and, because of non-instructive DNA lesions, often results in a nucleotide misincorporation. The second step is almost exclusively catalyzed by DNA polymerase ζ …

A Novel Role Of Human Dna Damage Checkpoint Protein Atr In Suppressing Ca2+ Overload-Induced Parp1-Mediated Necrosis, Hui Wang-Heaton

Electronic Theses and Dissertations

Ataxia telangiectasia and Rad3-related (ATR) is well known for its regulatory role in DNA damage responses (DDR) as a checkpoint kinase that phosphorylates hundreds of protein substrates. However, its role in cellular non-DNA damage stress responses (NDDR) is unknown. Necrosis is one form of cell death and traditionally has been regarded as a passive and uncontrolled cell death. Recently, evidence has emerged to support the concept that necrosis also may occur in a programmed manner and that PARP1 can be a mediator. Active poly (ADP-ribose) polymerase 1 (PARP1) hydrolyzes nicotinamide adenine dinucleotide (NAD⁺) to produce poly (ADP-ribose) (PAR) …

The Role Of Phosphorylation In Pam2 Motif-Containing Proteins Mediated Messenger Rna Deadenylation, Kai-Lieh Huang

Dissertations & Theses (Open Access)

Phosphorylation regulates many cellular processes. However, its role in mRNA deadenylation, a process to remove poly adenosines from the mature mRNA 3’ end tail, is unclear. The length of poly(A) tail determines mRNA stability and translation efficiency. Poly(A)-binding protein (PABP), which binds to newly synthesized poly(A) tails homogeneously and is known as a scaffold protein for PAM2 motif-containing proteins, plays a pivotal role in the shortening of poly (A) tails. This study is to examine the role of phosphorylation of PAM2 motif–containing proteins in regulating their interactions with PABP and mRNA deadenylation function.

The PAM2 motif, a region required for …

The Effects Of Phytohormones And Isoprenoids In Dihydroartemisinin-Induced Dormancy In The Erythrocytic Stages Of Plasmodium Falciparum, Marvin Duvalsaint Duvalsaint

USF Tampa Graduate Theses and Dissertations

Our ability to control malaria has been challenged by increasing antimalarial resistance. Plasmodium falciparum undergoes dormancy in the blood stages which is hypothesized to be a means by which they are able to survive under drug pressure. This helps select for resistant parasites which grow following removal of drug. The mechanisms behind dormancy and the subsequent recrudescence are not fully understood but translating knowledge from related organisms which undergo a similar phenomenon might shed some light. Higher plants utilize dormancy during the early development stages to survive under unfavorable conditions, increasing fitness of the seedling and ensuring viability when this …

Significance Of Pten Phosphorylation And Its Nuclear Function In Lung Cancer, Prerna Malaney

USF Tampa Graduate Theses and Dissertations

Phosphorylation mediated inactivation of PTEN leads to multiple malignancies with increased severity. However, the consequence of such inactivation on downstream functions of PTEN are poorly understood. Therefore, the objective of my thesis is to ascertain the molecular mechanisms by which PTEN phosphorylation drives lung cancer. PTEN phosphorylation at the C-terminal serine/threonine cluster abrogates its tumor suppressor function. Despite the critical role of the PTEN C-tail in regulating its function, the crystal structure of the C-tail remains unknown. Using bioinformatics and structural analysis, I determined that the PTEN C-tail is an intrinsically disordered region and is a hot spot for post-translational …

Characterizing The Inhibition Of Katanin Using Tubulin Carboxy-Terminal Tail Constructs, Corey E. Reed

Masters Theses

Understanding how the cellular cytoskeleton is maintained and regulated is important to elucidate the functions of many structures such as the mitotic spindle, cilia and flagella. Katanin p60, microtubule-severing enzymes from the ATPase associated with cellular activities (AAA+) family, has previously been shown in our lab to be inhibited by free tubulin as well as α- and β-tubulin carboxy-terminal tail (CTT) constructs. Here we investigate the inhibition ability of several different tubulin CTT sequences. We quantify the effect of the addition of these constructs on the severing and binding activity of katanin. We find that some constructs inhibit katanin better …

The Biological Function Of Hammerhead Rana Ribozyme In Human Genome, Ibtehal M. A. Awad

Theses

Hammerhead RNA [HHR] sequence originally found in viroids is also detected in many species. HHR are often found in introns of different genes ranging from prokaryotes to

eukaryotes. HHR can form specific tertiary structure that make specific region susceptible to cleavage. However, the role of the HHR is not clear in other life forms. This study aims to

Investigate the role of HHR in the intron 6 of (RECK) gene. Our study shows that when blocking the HHR sequence in the intron6, the production of RECK protein declines which may be due to the effect of HHR in splicing and …

Identification And Characterization Of The Anticancer Potential Of Indigenous Medicinal Plants Of The Arabian Peninsula, Sameera Omar Mohammed Saeed Balhamar

Theses

Indigenous plant species historically used for their medicinal properties are a tremendous source for bringing newer and safer drugs to the market. A concerted effort is needed to characterize their medicinal potential and identify new molecules that could be exploited in modern medicine. The current study was undertaken to study the anticancer properties of several indigenous plants that are used by the local population of the Arabian Peninsula and beyond for various medicinal purposes. Towards this end, we acquired different plant extracts from five plants, namely Boswellia sacra (BS), Cleome droserifolia (CD), Teucrium muscatensis (TM), Orchadenus arabicus (OA), and Acredocarpus …

Specific Binding Affinity Of The Non-Catalytic Domain Of Eukaryotic Like Type Ib Topoisomerase Of Vaccinia Virus, Benjamin R. Reed

Dissertations, Theses, and Capstone Projects

Topoisomerases are ubiquitous proteins that alter supercoiling in double stranded DNA (dsDNA) during transcription and replication and. vaccinia and the closely related poxvirus variola virus, at 314 amino acids in length, encode the smallest of the type I topoisomerases(TopIB). TopIB is a two domain protein that recognizes the sequence 5’-T/CCCTT, cleaves at the 3’-end and relaxes supercoiling through rotation. The C-terminal domain (CTD) alone contains the catalytic activity and specificity. Deletion of the N-terminal domain results in a greatly reduced rate of relaxation and rapid dissociation. Biochemical data suggests that the N-terminal domain (NTD) is important for pre-cleavage binding and …

Molecular Analysis Of Ftsz-Ring Assembly In E. Coli Cytokinesis, Kuo-Hsiang Huang

Dissertations, Theses, and Capstone Projects

An essential first step in bacterial division is the assembly of a cytokinetic ring (Z-ring) formed by the tubulin-like FtsZ at midcell. The highly conserved core domain of FtsZ has been reported to mediate assembly of FtsZ polymers in vivo and in vitro. Species-specific differences in the FtsZ C-terminal domain such as the FtsZ CTV region and interactions with several modulatory proteins such as ZapC and ZapD, restricted to certain bacterial classes, also serve as key determinants of FtsZ protofilament bundling. Here, we characterize (i) the roles of the FtsZ CTV region in mediating both longitudinal and lateral interactions …

Tuning Into Toxins And Channels: The Characterizations Of Tv1 And A Human Cardiac Sodium Channel Voltage-Sensor Domain, Mohammed H. Bhuiyan

Dissertations, Theses, and Capstone Projects

In nature, peptide toxins are an abundant resource, produced both by marine and terrestrial organisms. A major target of these peptide toxins is the group of the highly important voltage-gated ion channels. Due to their high specificity and affinity, peptide toxins have been used for over a decade in discovery and characterization of voltage-gated ion channels. Although peptide toxins have been extensively characterized structurally, the structural characterization of eukaryotic voltage-gated sodium channels has seen much less progress, due to their large size and high hydrophobicity. Voltage-gated sodium channels play crucial roles in many physiological processes, and when these processes are …

Development Of A Novel Class Of Chemicals For Labeling Abasic Sites In Cellular Dna And Killing Cancer Cells, Shanqiao Wei

Wayne State University Dissertations

Abasic (AP) sites are the most common type of lesions in DNA. Numerous endogenous and exogenous agents and cellular processes can induce the formation of AP sites in DNA. If left unrepaired, the deleterious AP sites cause mutagenesis and cytotoxicity. Methoxyamine is known to react with AP sites and block base excision repair. Another alkoxyamine, aldehyde-reactive probe (ARP) tags AP sites with a biotin and has been widely used to quantify these sites. In this study, I have combined both these abilities into one alkoxyamine, AA3, which reacts toward AP sites with better reactivity than ARP at physiological pH. Additionally, …

Role Of Ddr1 In Pancreatic Cancer, Huocong Huang

Theses & Dissertations

Pancreatic ductal adenocarcinomas are highly malignant cancers, characterized by extensive invasion into surrounding tissues, metastasis to distant organs at a very early stage, and a limited response to therapy. One of the main features of pancreatic ductal adenocarcinomas is desmoplasia, which leads to extensive deposition of collagen I. We have demonstrated that collagen I can induce epithelial-mesenchymal transition (EMT) in pancreatic cancer cells. A hallmark of EMT is an increase in the expression of a mesenchymal cadherin, N-cadherin. Our previous studies have shown that up-regulation of N-cadherin can promote tumor cell invasion and that collagen I-induced EMT is through two …

Study Of The Structure-Related Functions Of Eukaryotic Primase-Pol Alpha Complex During Replication, Yinbo Zhang

Theses & Dissertations

During eukaryotic replication primase•polymerase α (prim•polα) complex synthesizes de novo chimeric primers composed of about 10 nt RNA and 20 nt DNA, which are subsequently extended by main replicative DNA polymerases (pol), polε and polδ, on leading and lagging strands, respectively. It is estimated that prim•polα initiates more than 10 millions of lagging strand Okazaki fragments in human genome in each replication cycle. A concerted action of the two active sites, RNA pol and DNA pol, is required to ensure the efficient priming. A remarkable feature of the prim•polα complex is the “programmed” synthesis of the chimeric primer, where the …

Insights Into Chibby's Structural Elements And Their Interplay In Wnt Signaling Protein-Protein Interactions, Ryan C Killoran

Electronic Thesis and Dissertation Repository

The Wnt/b-catenin signaling pathway is critical to embryonic development and adult tissue homeostasis. Mutations to Wnt signaling components can cause dysregulation of the pathway, leading to various human diseases such as cancer. The partially disordered protein Chibby (Cby) is a conserved nuclear protein that acts as an antagonist in the Wnt/b-catenin signaling pathway. Cby’s antagonism is accomplished via two mechanisms. First, by competing with the Tcf/Lef family of transcription factors, Cby abrogates the b-catenin-mediated transcription of Wnt signaling genes. Moreover, upon phosphorylation on serine 20 by the kinase Akt, Cby forms a complex with the protein 14-3-3 to facilitate the …

Electron Transport To Photosystem I By Soluble Carriers: Evolution Of The Interacting Pair, Khoa Dang Nguyen

Doctoral Dissertations

Oxygenic photosynthesis is driven via sequential action of Photosystem II (PSII) and (PSI) reaction centers via the Z-­‐scheme. Both of these pigment– membrane protein complexes are found in cyanobacteria, algae, and plants. PSI, unlike PSII, is remarkably stable and does not undergo limiting photo-­‐damage. This stability, as well as other fundamental structural differences, makes PSI the most attractive reaction centers for applied photosynthetic applications. These applied applications exploit the efficient light harvesting and high quantum yield of PSI where the isolated PSI particles are redeployed providing electrons directly as a photocurrent or, via a coupled catalyst to yield H2. Here, …

Modification Of Carbohydrate Active Enzymes In Switchgrass (Panicum Virgatum L.) To Improve Saccharification And Biomass Yields For Biofuels, Jonathan Duran Willis

Doctoral Dissertations

The natural recalcitrance of plant cell walls is a major commercial hurdle for plant biomass to be converted into a viable energy source as alternative to fossil fuels. To circumvent this hurdle manipulation of carbohydrate enzymes active in the cellulose and hemicellulose portions of the plant cell wall can be utilized to improve feedstocks. Production of cellulolytic enzymes by plants have been evaluated for reducing the cost associated with lignocellulosic biofuels. Plants have successfully served as bioreactors producing bacterial and fungal glycosyl hydrolases, which have altered plant growth to improve saccharification. A bioprospecting opportunity lies with the utilization of insect …

Characterization Of An Ethylene Receptor In Synechocystis Sp. Pcc 6803, Randy Francis Lacey

Doctoral Dissertations

In plants, ethylene functions as a hormone regulating many growth and developmental processes. Ethylene receptors in plants resemble bacterial two-component signaling systems. Because of this it, ethylene receptors are thought to have been acquired by gene transfer from the cyanobacterial endosymbiont that lead to the development of the chloroplast. However, prior to this work, functional ethylene receptors were thought to only be found in green plants. Here, we show that the cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis) contains a functional ethylene receptor, SynEtr1. SynEtr1 contains a predicted ethylene binding domain, a photosensory cyanobacteriochrome (CBCR) domain, and a histidine …

Intestinal Cytoplasmic Lipid Droplets, Associated Proteins, And The Regulation Of Dietary Fat Absorption, Theresa M. D'Aquila

Open Access Dissertations

Dietary fat provides essential nutrients, contributes to energy balance, and regulates blood lipid concentrations. These functions are important to health, but can also become dysregulated and contribute to diseases such as obesity, diabetes, and cardiovascular disease. The small intestine absorbs dietary fat through an efficient multi step process of digestion, uptake, metabolism, and secretion or storage. When dietary fat is taken up by the absorptive cells of the small intestine, enterocytes, it can be secreted into circulation where it contributes to blood lipid levels or temporarily stored in cytoplasmic lipid droplets (CLDs). The objective of this dissertation is to investigate …

Investigating The Roles Of Δnp63 As A Suppressor Of Migration, Invasion, And Metastasis, Ramon E. Flores Gonzalez

Dissertations & Theses (Open Access)

Cancer is one of the leading causes of death and disease in the world. Considerable resources are spent to study and understand cancer, with the hope of developing new treatments and eventually cures that will help millions of people. Efforts to understand cancer are hindered by its inherent complexity and instability. Nonetheless, understanding the basics of tumor development and progression are the key to focused on studying the role of ΔNp63 in cancer, a p53 family member known to be involved in epithelial development, microRNA biogenesis, and stem cell maintenance. Using the strength of in vivo mouse models, we found …

Applications Of The Gst- Affinity Tag In The Purification And Characterization Of Proteins, Wibke Beatrice Kachel

Graduate Theses and Dissertations

With the latest innovations in biological sciences, large quantities of biologically active polypeptides as well as high throughput screening methods to quickly evaluate if these biomolecules potentially have therapeutic, diagnostic, or industrial purposes are required. The synthesis and purification of peptides and small proteins continue to be demanding as the production of high yields through chemical synthesis can involve large costs. On the other hand, there are only few examples of acquiring those biomolecules through cloning and expression in bacterial systems in form of recombinant fusion proteins. Glutathione S-Transferase (GST) is not only a very commonly used affinity tag to …

Defining The Functions Of Usp22 And Usp44 In Regulation Of H2bub1 Levels, Xianjiang Lan

Dissertations & Theses (Open Access)

Aberrant levels of histone ubiquitination are involved in various human diseases including neurodegenerative disorders and cancers. Particularly, Histone H2B monoubiquitination (H2Bub1) is highly associated with gene regulation in both normal cells and diseases. Many deubiquitinases (mainly USPs) are defined to regulate global H2Bub1 levels. However, how these USPs are regulated and how they contribute to diseases are not well understood.

USP22, part of the deubiquitination module (DUBm) in the SAGA complex, is a well-defined regulator of H2Bub1 levels. ATXN7, another crucial subunit of the SAGA DUBm, is involved in a neurodegenerative disease, spinocerebellar ataxia type 7 (SCA7), due to a …

Control Of Proteolysis During The Caulobacter Cell Cycle, Joanne Lau

Doctoral Dissertations

Intracellular protein destruction is a carefully coordinated and timed regulatory mechanism that cells utilize to modulate growth, adaptation to environmental cues, and survival. In Caulobacter crescentus, a bacterium known for studies of bacterial cell division cycle, the response regulator CpdR couples phosphorylation events with the AAA+ protease ClpXP to provide punctuated degradation of crucial substrates involved in cell cycle regulation. CpdR functions like an adaptor to alter substrate choice by ClpXP, however it remains unclear how CpdR influences its multiple targets. In this thesis, we show that, unlike canonical ClpXP adaptors, CpdR alone does not strongly bind its substrate. …

Characterization Of Numb As A Regulator Of Anaplastic Lymphoma Kinase, Ran Wei

Electronic Thesis and Dissertation Repository

Cellular events rely on protein-protein interactions that are often mediated by modular domains which recognize particular sequence motifs in binding partners. The NUMB protein is the first described cell fate determinant and multifaceted adaptor that is involved in a wide variety of cellular events. NUMB mainly mediates protein interactions via its modular PTB domain. Here we present a systematic investigation of the NUMB-PTB interactome by employing an integrative strategy combining both protein and peptide arrays. We profiled NUMB-PTB binding specificity and interacting proteins genome-wide. The receptor tyrosine kinases (RTKs) are found highly enriched in the interactome, raising the possibility that …

Circular Oligodeoxynucleotides (Coligos) As Chemically Synthesized, Promoter-Independent Small Rna Expression Vectors, Lodoe Lama

Dissertations, Theses, and Capstone Projects

Small RNAs (sRNA) such as microRNA (miRNA), small interfering RNA (siRNA), and other types of RNA have been found to play many important biological roles in regulation of different cellular process leading to their possible use as therapeutics. However, one of the biggest hurdles in exploiting these sRNAs in therapeutics has been the difficulty in delivering them safely and stably into human tissues. Many delivery approaches have been undertaken to deliver these sRNA, albeit with many shortcomings in terms of cost, stability, and side effects, necessitating the need for alternative approaches. We are exploring an entirely different approach for conveying …

Purification And Characterization Of Antibodies Against Killifish Hif-1Α, Janet Gonzalez-Rosario

University of New Orleans Theses and Dissertations

Many fish face low oxygen concentrations (hypoxia) in their natural environments, and they respond to hypoxia through a variety of behavioral, physiological, and cellular mechanisms. Some of these responses involve changes in gene expression. In mammals, the hypoxia inducible factor (HIF) family of transcription factors are the “master regulators” of gene expression during hypoxia, but the study of HIF in fish has been hampered by the lack of reagents to detect this protein in non-mammalian vertebrates. The goals of this thesis are to affinity purify antibodies against HIF from the killifish Fundulus heteroclitus and use them to recover and quantify …

Determining The Role Of Erbeta In The Activation Of Erk1/2 By The Environmental Estrogens, Cadmium Chloride And Sodium Arsenite, In Human Lung Adenocarcinoma Cells, Jeffrey Hyzer

Undergraduate Theses

Estrogen is involved in the proliferation of adenocarcinoma lung cells. However, the proliferative role of two endocrine disrupters, cadmium chloride and sodium arsenite, in lung adenocarcinoma is less clear. Previous studies have shown that these two heavy metals can induce cellular proliferation and activate phosphorylation of ERK1/2 in a human lug adenocarcinoma cell line, NCI-H1793. Induced phosphorylation of ERK1/2 by these compounds is decreased in the presence of an estrogen receptor antagonist, ICI-182,780, suggesting that cadmium and arsenite stimulate these responses, in part, via a non-genomic estrogen signaling pathway. There are three known estrogen receptors, but it is unclear which …