Cell Biology Commons^™

Establishing The Role Of The Pancreatic Transcription Factor Mist1 In Xbp1-Mediated Maintenance Of Pancreatic Acinar Cell Homeostasis, David Alan Hess

Open Access Dissertations

Pancreatic acinar cells (PACs) continuously produce more protein than any other cell type in the human body. As a result, PACs and other specialized secretory cells have a constant demand placed on their protein synthetic and packaging machinery. When demand for secreted products exceeds the capacity of the cell's basal protein production facilities, dangerous accumulations of misfolded proteins can build up, resulting in a condition known as ER stress. To ameliorate this stress, secretory cells activate a coordinated, three-part compensatory network collectively known as the unfolded protein response (UPR) to both expand the capacity of the ER and directly assist …

Measuring And Modeling The Response Characteristics Of The Environmental Phosphate Transducer In Escherichia Coli, Chetan Sood

Open Access Dissertations

The PhoR/PhoB two-component system in Escherichia coli is a biological transducer that senses the limitation of environmental inorganic orthophosphate, the bacteria's preferred source of the essential nutrient phosphate, and transmits that information to the interior of the cell initiating a response that mitigates phosphate starvation. In the first part of this study, we present and apply a fluorescence microscopy technique to measure, in vivo, the dynamic response characteristics of the transducer with single-cell resolution. We report that the transience in the PhoR/PhoB TCS response is consistent with the transducer having a threshold sensitivity to the concentration of environmental phosphate, …

Protein Kinase Ck2 Phosphorylates And Activates P21-Activated Kinase 1, Yong Jae Shin, Yong-Bae Kim, Jeong-Ho Kim

Biochemistry and Molecular Medicine Faculty Publications

Activation of the p21-activated kinase 1 (PAK1) is achieved through a conformational change that converts an inactive PAK1 dimer to an active monomer. In this paper, we show that this change is necessary but not sufficient to activate PAK1 and that it is, rather, required for CK2-dependent PAK1S223 phosphorylation that converts a monomeric PAK1 into a catalytically active form. This phosphorylation appears to be essential for autophosphorylation at specific residues and overall activity of PAK1. A phosphomimetic mutation (S223E) bypasses the requirement for GTPases in PAK1 activation, whereas the constitutive activity of the PAK1 mutant (PAK1H83,86L), postulated to mimic GTPase-induced …

Identification Of Proteins Potentially Involved In The Formation Of Lafora Bodies, A Hallmark Of Lafora Disease, Elham Schokraie, Oliver Kötting, Matthew S. Gentry

Molecular and Cellular Biochemistry Presentations

Lafora Disease (LD) is a fatal teenage-onset progressive myoclonus epilepsy. It is characterized by the formation of Lafora bodies (LBs), deposits of abnormally branched, insoluble, hyperphosphorylated glycogen-like polymers that are generally believed to trigger the development of the clinical symptoms of LD. 58% and 35% of the LD cases are caused by mutations in EPM2A (laforin) and EPM2B (malin), respectively. However, little is known about their function in LB formation. Two different mechanisms have been proposed to explain the accumulation of insoluble LBs: first, excessive glycogen phosphorylation and, second, an imbalance between glycogen synthesizing enzymes. The present study aims at …

Effects Of Butyltins On Mitogen-Activated-Protein Kinase Kinase Kinase And Ras Activity In Human Natural Killer Cells, Lindsay J. Celada, Margaret M. Whalen

Chemistry Faculty Research

Butyltins (BTs) contaminate the environment and are found in human blood. BTs, tributyltin (TBT) and dibutyltin (DBT) diminish the cytotoxic function and levels of key proteins of human natural killer (NK) cells. NK cells are an initial immune defense against tumors, virally infected cells and antibody-coated cells and thus critical to human health. The signaling pathways that regulate NK cell functions include mitogen-activated protein kinases (MAPKs). Studies have shown that exposure to BTs leads to activation of specific MAPKs and MAPK kinases (MAP2Ks) in human NK cells. MAP2K kinases (MAP3Ks) are upstream activators of MAP2Ks, which then activate MAPKs. The …

Pseudomonas Aeruginosa Exotoxin Y-Mediated Tau Hyperphosphorylation Impairs Microtubule Assembly In Pulmonary Microvascular Endothelial Cells, Ron Balczon, Nutan Prasain, Cristhiaan Ochoa, Jason Prater, Bing Zhu, Mikhail Alexeyev, Sarah Sayner, Dara W. Frank, Troy Stevens

University Faculty and Staff Publications

Pseudomonas aeruginosa uses a type III secretion system to introduce the adenylyl and guanylyl cyclase exotoxin Y (ExoY) into the cytoplasm of endothelial cells. ExoY induces Tau hyperphosphorylation and insolubility, microtubule breakdown, barrier disruption and edema, although the mechanism(s) responsible for microtubule breakdown remain poorly understood. Here we investigated both microtubule behavior and centrosome activity to test the hypothesis that ExoY disrupts microtubule dynamics. Fluorescence microscopy determined that infected pulmonary microvascular endothelial cells contained fewer microtubules than control cells, and further studies demonstrated that the microtubule-associated protein Tau was hyperphosphorylated following infection and dissociated from microtubules. Disassembly/reassembly studies determined that …

Early Innate Immunity Determines Outcome Of Mycobacterium Tuberculosis Pulmonary Infection In Rabbits, Selvakumar Subbian, Nirmalya Bandyopadhyay, Liana Tsenova, Paul O'Brien, Viraj Khetani, Nicole L. Kushner, Blas Peixoto, Patricia Soteropoulos, Joel S. Bader, Petros C. Karakousis, Dorothy Fallows, Gilla Kaplan

Publications and Research

Background: Pulmonary infection of humans by Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), results in active disease in 5-10% of individuals, while asymptomatic latent Mtb infection (LTBI) is established in the remainder. The host immune responses that determine this differential outcome following Mtb infection are not fully understood. Using a rabbit model of pulmonary TB, we have shown that infection with the Mtb clinical isolate HN878 (a hyper-virulent W-Beijing lineage strain) leads to progressive cavitary disease similar to what is seen in humans with active TB. In contrast, infection with Mtb CDC1551 (a hyper-immunogenic clinical isolate) is efficiently …

P53'S Choice Of Myocardial Death Or Survival: Oxygen Protects Infarct Myocardium By Recruiting P53 On Nos3 Promoter Through Regulation Of P53-Lys118 Acetylation, Rajan Gogna, Esha Madan, Mahmood Khan, Uttam Pati, Periannan Kuppusamy

Dartmouth Scholarship

Myocardial infarction, an irreversible cardiac tissue damage, involves progressive loss of cardiomyocytes due to p53-mediated apoptosis. Oxygenation is known to promote cardiac survival through activation of NOS3 gene. We hypothesized a dual role for p53, which, depending on oxygenation, can elicit apoptotic death signals or NOS3-mediated survival signals in the infarct heart. p53 exhibited a differential DNA-binding, namely, BAX-p53RE in the infarct heart or NOS3-p53RE in the oxygenated heart, which was regulated by oxygen-induced, post- translational modification of p53. In the infarct heart, p53 was heavily acetylated at Lys118 residue, which was exclusively reversed in the oxygenated heart, apparently regulated …

Modulation Of Bax/Bak Dependent Apoptosis By Sirtuin 3 And Mitochondrial Permeability Transition By Sirtuin 4, Manish Verma

Graduate School of Biomedical Sciences Theses and Dissertations

Mitochondria are dynamic organelles that regulate a myriad of cellular functions, including energy production and metabolic regulation. Mitochondria are also a critical regulator of cell death signaling cascades modulating both apoptotic and necrotic cell death. However, what determines which cell death pathway is activated is still unclear. The mitochondrial/intrinsic pathway of apoptosis is dependent on the activation of pro-apoptotic proteins, Bax and Bak, which induce mitochondrial outer membrane permeabilization (MOMP). Once the integrity of outer mitochondrial membrane (OMM) is compromised, pro-apoptotic intermembrane space proteins like cytochrome c, Smac/Diablo, Omi/HtrA2 and AIF are released into the cytoplasm, which activates the post-mitochondrial …

Med13p Prevents Stress-Independent Mitochondrial Hyperfragmentation And Aberrant Apoptosis Activation In Saccharomyces Cerevisiae By Controlling Cyclin C Nuclear Localization, Svetlana Khakhina

Graduate School of Biomedical Sciences Theses and Dissertations

During aging, and as a result of environmental changes, cells are exposed to elevated levels of reactive oxygen species (ROS). High ROS levels induce lipid oxidation, protein aggregation, mitochondrial hyperfragmentation, DNA damage and programmed cell death (PCD), also called apoptosis. PCD is a highly regulated process and its misregulation has been linked to neurodegenerative diseases and cancer development.

Our hypothesis is that cyclin C plays a role in the initiation of apoptosis. During normal conditions, cyclin C represses the transcription of stress response genes (SRG). In response to stress, cyclin C translocates to the cytoplasm where it facilitates mitochondrial hyperfragmentation …

Proteomic And Biochemical Studies Of Estrogen-Mediated Signaling And Novel Estrogen Receptor-Interacting Proteins In Breast Cancer Cells, Zhenqi Zhou

Graduate Theses and Dissertations

Estrogen plays essential roles in the growth, development, and homeostasis of a number of tissues, and can also be linked to the growth of breast cancer. The biological activities of estrogen are mediated by estrogen receptors (ERs) ERá and ERâ, and also orphan G-protein-coupled receptor 30 (GPR30). In order to identify novel proteins that are involved in ER-mediated actions of estrogen, we used mass spectrometry-based quantitative proteomic methods to systematically profile global protein expression in responses to E2 (17â-estradiol) stimulation in human breast cancer cell, and identify and characterize cellular novel proteins that are associated with ERs in breast cancer …

Recurrent Modification Of A Conserved Cis-Regulatory Element Underlies Fruit Fly Pigmentation Diversity, William A. Rogers, Joseph R. Salomone, David J. Tacy, Eric M. Camino, Kristen A. Davis, Mark Rebeiz, Thomas M. Williams

Biology Faculty Publications

The development of morphological traits occurs through the collective action of networks of genes connected at the level of gene expression. As any node in a network may be a target of evolutionary change, the recurrent targeting of the same node would indicate that the path of evolution is biased for the relevant trait and network. Although examples of parallel evolution have implicated recurrent modification of the same gene and cis-regulatory element (CRE), little is known about the mutational and molecular paths of parallel CRE evolution. InDrosophila melanogaster fruit flies, the Bric-à-brac (Bab) transcription factors control the development …

A Force Of Nature: Molecular Mechanisms Of Mechanoperception In Plants, Gabriele B. Monshausen, Elizabeth S. Haswell

Biology Faculty Research

The ability to sense and respond to a wide variety of mechanical stimuli-gravity, touch, osmotic pressure, or the resistance of the cell wall-is a critical feature of every plant cell, whether or not it is specialized for mechanotransduction. Mechanoperceptive events are an essential part of plant life, required for normal growth and development at the cell, tissue, and whole-plant level and for the proper response to an array of biotic and abiotic stresses. One current challenge for plant mechanobiologists is to link these physiological responses to specific mechanoreceptors and signal transduction pathways. Here, we describe recent progress in the identification …

Post-Injury Calcium Chelation Rescues Skeletal Muscle Regeneration In Mice, Matthew D. Magda

Honors Scholar Theses

During aging the ability of skeletal muscle to regenerate after injury wanes until muscle integrity cannot be maintained. In this study it is shown that calcium chelation can restore young-like regenerative ability in an aged mouse model of skeletal muscle regeneration.

Characterization Of Jak, Stat, And Src Interactions In Head And Neck Squamous Cell Carcinoma, Reshma Jaseja, Reshma Jaseja

Dissertations and Theses (Open Access)

Recurrence of Head and Neck Squamous Cell Carcinoma (HNSCC) is common; thus, it is essential to improve the effectiveness and reduce toxicity of current treatments. Proteins in the Src/Jak/STAT pathway represent potential therapeutic targets, as this pathway is hyperactive in HNSCC and it has roles in cell migration, metastasis, proliferation, survival, and angiogenesis. During short-term Src inhibition, Janus kinase (Jak) 2, and signal transducer and activator of transcription (STAT) 3 and STAT5 are dephosphorylated and inactivated. Following sustained Src inhibition, STAT5 remains inactive, but Jak2 and STAT3 are reactivated following their early inhibition. To further characterize the mechanism of this …

The Role Of K63-Linked Ubiquitination Cycles In Akt Kinase Activation, Wei-Lei Yang

Dissertations and Theses (Open Access)

Akt (also known as protein kinase B) serves a central regulator in PI3K/Akt signaling pathways to regulate numerous physiological functions including cell proliferation, survival and metabolism. Akt activation requires the binding of Akt to phospholipid PIP3 on the plasma membrane and subsequent phosphorylation of Akt by its kinases. Growth factor-mediated membrane recruitment of Akt is a crucial step for Akt activation. However, the mechanism of Akt membrane translocation is unclear. Protein ubiquitination is a significant posttranslational modification that controls many biological functions such as protein trafficking and signaling activation. Therefore, we hypothesize that ubiquitination may be involved in Akt signaling …

Divergent Mechanisms Of Interaction Of Helicobacter Pylori And Campylobacter Jejuni With Mucus And Mucins, Julie Ann Naughton, Karina Mariño, Brendan Dolan, Colm Reid, Ronan Gough, Mary Gallagher, Michelle Kilcoyne, Jared Gerlachscience,, Lokesh Joshi, Pauline Rudd, Stephen Carrington, Billy Bourke, Marguerite Clyne

Articles

Helicobacter pylori and Campylobacter jejuni colonize the stomach and intestinal mucus, respectively. Using a combination of mucus-secreting cells, purified mucins, and a novel mucin microarray platform, we examined the interactions of these two organisms with mucus and mucins. H. pylori and C. jejuni bound to distinctly different mucins. C. jejuni displayed a striking tropism for chicken gastrointestinal mucins compared to mucins from other animals and preferentially bound mucins from specific avian intestinal sites (in order of descending preference: the large intestine, proximal small intestine, and cecum). H. pylori bound to a number of animal mucins, including porcine stomach mucin, but …

Oncogenic Transformation Of Mammary Epithelial Cells By Transforming Growth Factor Beta Independent Of Mammary Stem Cell Regulation, Karen A. Dunphy, Jae-Hong Seo, Daniel J. Kim, Amy L. Roberts, James Direnzo, Amanda Balboni

Dartmouth Scholarship

BackgroundTransforming growth factor beta (TGFβ) is transiently increased in the mammary gland during involution and by radiation. While TGFβ normally has a tumour suppressor role, prolonged exposure to TGFβ can induce an oncogenic epithelial to mesenchymal transition (EMT) program in permissive cells and initiate the generation of cancer stem cells. Our objective is to mimic the transient exposure to TGFβ during involution to determine the persistent effects on premalignant mammary epithelium.

Evaluating Itpr-Dependence Of Apoptotic Signaling From The Endoplasmic Reticulum, Agustin Vargas, Jay L. Brewster

Featured Research

Stress within the endoplasmic reticulum (ER) can be induced by misfolded proteins accumulating in the lumen of this organelle. Signaling of ER stress to other parts of the cell results in altered gene expression, physiological adaptation, and with sustained stress, apoptosis (cell suicide). ER stress is often studied with highly toxic compounds that create severe ER stress rapidly, and a condition that is likely not physiologically relevant within an organism. In this study, we examine the apoptotic signaling induced by moderate ER stress, and in particular the inositol 1,4,5-trisphosphate receptor (ITPR). The ITPR regulates Ca2+ release from the ER lumen, …

Lysophosphatidic Acid Stimulates Lymphangiogenesis In Human Lymphatic Endothelial Cells, John Macbeth, Donna Nofziger-Plank

Featured Research

Lymphangiogenesis is the process by which new lymphatic vessels sprout and grow from existing vessels whether under developmental, immunological, or cancerous conditions. Proper lymphatic vessel formation is important in working alongside normal angiogenesis in order to help regulate the body’s tissue fluid as well as aid in immunosurveillance. Various factors regulate lymphangiogenesis such as members of the vascular endothelial growth factor family (VEGF). Another factor that has recently been identified to play a role in lymphangiogenesis is the bio-active phospholipid lysophosphatidic acid (LPA) however the molecular mechanism by which LPA regulates lymphangiogenesis has not been well characterized. In this study, …