Biochemistry Commons^™

A Pkcα-Mediated Growth Suppressive Mek-Erk Signaling Axis In Intestinal Epithelial Cells, Navneet Kaur

Theses & Dissertations

Members of the protein kinase C (PKC) family of serine/threonine kinases are involved in regulation of fundamental cellular functions, including proliferation, differentiation, survival, migration, and transformation. Increasing evidence points to anti-proliferative and tumor suppressive role of PKCs. Our laboratory and others have reported that the classical PKC isozyme, PKCαnegatively regulates proliferation and tumorigenesis in the intestinal epithelium. Our laboratory has further determined that PKCα signaling induces a program of cell cycle withdrawal in intestinal epithelial cells that involves downregulation of the pro-proliferative proteins, cyclin D1 and Id1, and upregulation of the cyclin dependent kinase (CDK) inhibitor, p21^Cip1. Unexpectedly, …

Molecular Mechanisms Of Aberrant Protein Glycosylation In Pancreatic Cancer Stemness And Metastasis, Frank Leon

Theses & Dissertations

A myriad of genetic and other abnormal changes underlies the aggressiveness and dissemination properties observed in pancreatic cancer (PC). Aberrant protein glycosylation is a commonly observed feature in PC. The modification of protein O-glycosylation is mediated by glycosyltransferases, which attach and sequentially elongate monosaccharides on Serine/Threonine (Ser/Thr) motifs. Aberrant glycosylation is recognized as an emerging hallmark of cancer where a disruption in normal glycosylation results in irregular O-glycans.

This dissertation research has investigated the consequences of aberrant protein glycosylation on stemness and enhancement of metastatic properties in pancreatic ductal adenocarcinoma (PDAC). Several publications have reported aberrant O-glycosylation increases in oncogenic …

Erecta Family Genes Regulate The Shoot Apical Meristem And Organ Formation, Daniel A. Degennaro

Doctoral Dissertations

Plants are sessile and must adjust their organ growth to their environments. A reservoir of stem cells in the shoot apical meristem (SAM) supplies cells for differentiation into organs. The SAM must balance organ production with stem cell maintenance. The ERECTA family (ERfs) encodes the leucine-rich repeat receptor-like kinases ERECTA (ER), ERECTA-LIKE 1 (ERL1), and ERL2. ERf signaling regulates organ initiation and stem cell maintenance. Results presented in this work include the following:

1) WUSCHEL (WUS) and CLAVATA3 (CLV3) make up a negative feedback loop to maintain SAM size. WUS and CLV3 expression localization is critical for …

Engineering Fluorescently Labeled Human Fibroblast Growth Factor One Mutants And Characterizing Their Photophysics Properties Towards Designing Fret Assays, Mamello Mohale

Graduate Theses and Dissertations

Human fibroblast growth factor one (hFGF1) belongs to a family of 22 FGF members produced by fibroblast cells. Cell signaling during physiological processes of angiogenesis and wound healing occurs when hFGF1 binds to its receptor (FGFR). However, when heterogenous homeostasis is not maintained, fibroblast cells exhibit excessive proliferation which can lead to a myriad of cancers. smFRET is an ultrasensitive distant dependent (1-10 nm) technique capable of resolving such heterogeneity in structural dynamics and binding affinities (Kd). Therefore, we successfully designed and characterized fluorescently labeled hFGF1 tracers which span the visible light region of the electromagnetic spectrum for use in …

Investigating Effects Of Microenvironmental Stress On Cell Metabolism Using Multiphoton Imaging, Lisa Rebello

Graduate Theses and Dissertations

Resistance to therapy in cancer is a major cause of poor prognosis in patients. Tumor hypoxia plays an active role in mediating treatment resistance and has been linked to metastases and metastatic potential in cancer. Our research focused on three objectives: i) To understand metabolic effects of chronic and intermittent hypoxia in murine breast cancer cells and its affiliation with metastatic potential ii) To identify the metabolic changes associated with radiation therapy in a panel of radiosensitive and radioresistant human head and neck cancer cells and iii) to monitor the changes in cell metabolism associated with gain of treatment resistance. …

The Structural And Functional Role Of Photosensing In Rgs-Lov Proteins, Zaynab Jaber

Dissertations, Theses, and Capstone Projects

Light provides organisms with energy and spatiotemporal information. To survive and adapt, organisms have developed the ability to sense light to drive biochemical effects that underlie vision, entrainment of circadian rhythm, stress response, virulence, and many other important molecularly driven responses. Blue-light sensing Light-Oxygen-Voltage (LOV) domains are ubiquitous across multiple kingdoms of life and modulate various physiological events via diverse effector domains. Using a small molecule flavin chromophore, the LOV domain undergoes light-dependent structural changes leading to activation or repression of these catalytic and non-catalytic effectors. In silico analyses of high-throughput genomic sequencing data has led to the marked expansion …

Chemical Damage To Mrna And Its Impact On Ribosome Quality-Control And Stress-Response Pathways In Eukaryotic Cells, Liewei Yan

Arts & Sciences Electronic Theses and Dissertations

Ribosome often faces defective adducts that disrupt its movement along the mRNA template. These adducts are primarily caused by chemical damage to mRNA and are highly detrimental to the decoding process on the ribosome. Hence, unless dealt with, chemical damage to RNA has been hypothesized to lead to the production of toxic protein products. Even more detrimental is the ability of damaged mRNA to drastically affect ribosome homeostasis through stalling. This in turn would lead to greatly diminished translation capacity of cells. Therefore, the inability of cells to recognize and resolve translational-stalling events is detrimental to proteostasis and could even …

The Regulation Of Pannexin1 And Pannexin2 In The Skin In Health And Disease, Rafael E. Sanchez Pupo

Electronic Thesis and Dissertation Repository

Pannexins (PANX1, 2, 3) are a family of channel-forming glycoproteins that mediate intracellular and paracrine signaling. In contrast to PANX2, PANX1 has been extensively investigated in the skin, modulating cell differentiation, wound healing, and melanoma development. PANX1 and PANX2 can co-exist in the same cell and form mixed channels where their glycosylation seems to regulate their intermixing. N-glycosylation and caspase cleavage have been proposed as modulators of the function of PANX1, but their effects on PANX2 are unknown. We explored the PANX2 expression in mouse skin and showed that a Panx2 splice variant (PANX2-202) is continuously expressed throughout aging skin. …

Evaluating Bioenergetics And Mitochondrial Dynamics In Patient Fibroblasts With Pathogenic Mitochondrial Dna Mutations Causing Leigh Syndrome, Ajibola Bakare

Graduate Theses and Dissertations

Leigh syndrome (LS) is a rare fatal mitochondrial disorder of infants caused by pathogenic mutations in the nuclear (nDNA) or mitochondrial DNA (mtDNA) leading to mitochondrial dysfunction. The extent to which pathogenic mtDNA variants regulate disease severity in LS is not well understood. The heterogeneous nature of this disorder, based in part by complex mitochondrial genetics, and the nuclear and mitochondrial cross-talk has made it particularly challenging to investigate and develop therapies for treating LS . While the prognosis is poor, several studies are underway to understand the pathophysiology of LS. This dissertation provides a comprehensive structural and functional analysis …

Characterization And Modulatory Influence Of Pyruvate Kinase Muscle Isoforms 1 And 2 Within The Murine Pluripotent Continuum, Joshua G. Dierolf

Electronic Thesis and Dissertation Repository

Mouse embryonic stem cells (mESCs) and mouse epiblast stem cells (mEpiSCs) represent opposite ends of a pluripotency continuum, respectively referred to as naïve and primed pluripotent states. A third, recently discovered intermediate state has been described as the ‘formative state’. Metabolism has been traditionally regarded as a by-product of cell fate; however, recent evidence now supports metabolism as promoting stem cell fate. Pyruvate kinase muscle isoforms 1 and 2 (PKM1 and PKM2) catalyze the final, rate limiting step of glycolysis generating adenosine triphosphate (ATP) and pyruvate; however, the precise role(s) of these isozymes in naïve, formative, and primed pluripotency is …

Reconstituting The Cyanobacterial Circadian Clock In Vitro, Pyong Hwa Kim

Dissertations

Cyanobacteria are photosynthetic organisms that are known to be responsible for oxygenating Earth’s early atmosphere. Having evolved to ensure optimal survival in the periodic light/dark cycle on this planet, their genetic codes are packed with various tools, including a sophisticated biological timekeeping system. Among the cyanobacteria is Synechococcus elongatus PCC 7942, the simplest clock-harboring organism with a powerful genetic tool that enabled the identification of its intricate timekeeping mechanism. The three central oscillator proteins—KaiA, KaiB, and KaiC—drive the 24 h cyclic gene expression rhythm of cyanobacteria, and the "ticking" of the oscillator can be reconstituted inside a test tube just …

Role Of Endocytic Machinery Regulators In Egfr Traffic And Viral Entry, Insha Mushtaq

Theses & Dissertations

STUDY 1: Role of endocytic regulator EHD1 and its binding partner RUSC2 in EGFR traffic

Abstract

Epidermal growth factor receptor (EGFR) is a prototype receptor tyrosine kinase and an oncoprotein in many solid tumors. Cell surface display of EGFR is essential for cellular responses to its ligands. While post activation endocytic trafficking of EGFR has been well elucidated, little is known about mechanisms of basal/pre-activation surface display of EGFR. Here, we identify a novel role of the endocytic regulator EHD1 and a potential EHD1 partner, RUSC2, in cell surface display of EGFR. EHD1 and RUSC2 colocalize with EGFR in vesicular/tubular …

Potential Counter Regulatory Effects Of A Gut Microbiota Metabolite In Alleviating Down-Regulation Krüppel-Like Factor 4 In Intestinal Inflammation, Ylva Forslund

Theses, Dissertations and Capstones

Inflammatory bowel disease (IBD) is a medical condition characterized by chronic inflammation of the intestinal epithelium. Krüppel-like factor 4 (KLF4), a zinc finger transcription factor, is vital for maintaining intestinal epithelial homeostasis. KLF4 promotes differentiation of goblet cells that generate the protective mucus layer. Reduced goblet cell number and defective mucus layer are associated with IBD. Shortchain fatty acids (SCFA) are known to play an important role in the maintenance of a strong and healthy intestinal epithelial layer and also in goblet cell differentiation. However, whether the positive effects of SCFAs on goblet cells are mediated, at least partly, via …

Reversible Glucan Phosphorylation In The Red Alga, Cyanidioschyzon Merolae, Corey Owen Brizzee

Theses and Dissertations--Molecular and Cellular Biochemistry

Starch and glycogen are an essential component for the majority of species and have been developed to maintain homeostasis in response to environmental changes. Water-soluble glycogen is an excellent source of quick, short-term energy in response to energy demands. In contrast, plants and algae have developed the macromolecule starch that is elegantly suitable for their dependence on external circumstances. Semi-crystalline starch is water-insoluble and inaccessible to most amylolytic enzymes, thus plants and algae have developed a coordinated system so that these enzymes can gain access to the denser starch energy cache. Starch-like semi-crystalline polysaccharides are also found in red algae, …

Entry And Replication Of Negative-Strand Rna Viruses, Kerri Boggs

Theses and Dissertations--Molecular and Cellular Biochemistry

Hendra virus (HeV) and human metapneumovirus (HMPV) are negative-sense, singled-stranded RNA viruses. The paramyxovirus HeV is classified as a biosafety level 4 pathogen due to its high fatality rate and the lack of a human vaccine or antiviral treatment. HMPV is a widespread pneumovirus that causes respiratory tract infections which are particularly dangerous for young children, immunocompromised individuals, and the elderly. Like HeV, no vaccines or therapies are available to combat HMPV infections. These viruses fuse their lipid envelopes with a cell to initiate infection. Blocking cell entry is a promising approach for antiviral development, and many vaccines are designed …

Investigation Of Multidrug Efflux Transporter Acrb In Escherichia Coli: Assembly, Degradation And Dynamics, Prasangi Irosha Rajapaksha

Theses and Dissertations--Chemistry

The Resistant Nodulation Division (RND) super family member, tripartite AcrA-AcrB-TolC efflux pump, is a major contributor in conferring multidrug-resistance in Escherichia coli. The structure of the pump complex, and drug translocation by functional rotation mechanism have been widely studied. Despite of all these data, the dynamics of the assembly process of the pump and AcrB during functional rotation in the process of drug efflux remains poorly understood. My thesis focuses on understanding the pump assembly process, dynamics of AcrB in functional rotation mechanism, and also investigate the mechanism of degradation of AcrB facilitated by a C-terminal ssrA tag.

In the …

From Inner Segment To Outer Segment: Palmitoylation Of Photoreceptor Na+, K+-Atpase And The Importance Of Prcd In Photoreceptor Outer Segment Morphogenesis, Emily R. Sechrest

Graduate Theses, Dissertations, and Problem Reports

Photoreceptors are specialized neuroepithelial cells which are optimized for efficient capture of light and initiation of visual transduction. These cells have several compartments which are very important for proper visual function and segregation of cellular processes, including the outer segment (OS), inner segment (IS), nucleus, and synapse. The IS houses all of the cellular organelles and biosynthetic molecular machinery the cell requires and is the site of protein synthesis. The light-sensing OS is a highly modified, primary cilium, which contains many stacks of double membranous discs which house proteins required for formation and maintenance of OS structure, as well as …