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Full-Text Articles in Molecular Biology

Modulation Of Antitumor Immunity By The Mek Inhibitor Trametinib: Implications For Targeted Therapy Of Cancer, Michael J. Allegrezza Jan 2016

Modulation Of Antitumor Immunity By The Mek Inhibitor Trametinib: Implications For Targeted Therapy Of Cancer, Michael J. Allegrezza

Publicly Accessible Penn Dissertations

Through rational drug design, much progress has been made to develop small molecules that specifically inhibit the oncogenic signaling pathways driving malignant growth. However, the normal function of immune cells depends upon many of the same pathways inhibited by such targeted cancer therapies. Because the immune system can influence the growth of many cancers, I hypothesized that most small molecule inhibitors would have activity on leukocytes relevant in cancer, and this activity would contribute to their antitumor mechanisms. In order to test this hypothesis, I first screened a panel of over 40 small molecule inhibitors for their activity on proliferating ...


Molecular And Cellular Approaches Toward Understanding Dynein-Driven Motility, Swathi Ayloo Jan 2016

Molecular And Cellular Approaches Toward Understanding Dynein-Driven Motility, Swathi Ayloo

Publicly Accessible Penn Dissertations

Active transport is integral to organelle localization and their distribution within the cell. Kinesins, myosins and dynein are the molecular motors that drive this long range transport on the actin and microtubule cytoskeleton. Although several families of kinesins and myosins have evolved, there is only one form of cytoplasmic dynein driving active retrograde transport in cells. While dynactin is an essential co-factor for most cellular functions of dynein, the mechanistic basis for this evolutionarily well conserved interaction remains unclear. Here, I use single molecule approaches with purified dynein to reconstitute processes in vitro, and implement an optogenetic tool in neurons ...


Tamoxifen Mediated Metabolic Stress: Molecular Mechanism And Therapeutic Opportunities, Natalie Ann Daurio Jan 2016

Tamoxifen Mediated Metabolic Stress: Molecular Mechanism And Therapeutic Opportunities, Natalie Ann Daurio

Publicly Accessible Penn Dissertations

Tamoxifen is the most widely used adjuvant chemotherapeutic for the treatment of estrogen receptor (ER) positive breast cancer, yet a large body of clinical and preclinical data indicates that tamoxifen can modulate multiple cellular processes independently of ER status. Here, we describe the ER-independent effects of tamoxifen on tumor metabolism. Using combined pharmacological and genetic knockout approaches, we demonstrate that tamoxifen inhibits oxygen consumption via inhibition of mitochondrial complex I, resulting in an increase in the AMP/ATP ratio and activation of the AMPK signaling pathway in vitro and in vivo. We also show that tamoxifen-induced cytotoxicity is modulated by ...


Car Drivers And Fuel Sources: How Distinct Signaling Domains In Chimeric Antigen Receptors Reprogram T Cells, Omkar Uday Kawalekar Jan 2016

Car Drivers And Fuel Sources: How Distinct Signaling Domains In Chimeric Antigen Receptors Reprogram T Cells, Omkar Uday Kawalekar

Publicly Accessible Penn Dissertations

With breakthroughs in synthetic biology, improved cell culture techniques and advanced genetic engineering, it has now become possible to generate bi-specific primary human T cells with desired specificities. One mode of redirecting specificity is the modification of T cells to express chimeric antigen receptors (CARs). Recent studies indicate that natural T cells have distinct biochemical and metabolic features that endow them with short lived effector or long lived memory fates. The central objective of this thesis was to investigate whether the signaling endodomain of CARs could reprogram T cells with pre-specified effector and memory fates. This thesis describes a novel ...


Centromere Identity And The Nature Of The Cenp-A-Containing Nucleosome, Samantha Jane Falk Jan 2016

Centromere Identity And The Nature Of The Cenp-A-Containing Nucleosome, Samantha Jane Falk

Publicly Accessible Penn Dissertations

The centromere is an essential chromosomal locus that serves as the site of kinetochore formation, ensuring accurate chromosome segregation during mitosis and meiosis. While most centromeres form on repetitive DNA, the underlying DNA sequence is neither necessary nor sufficient to support centromere function, suggesting that this locus is epigenetically defined. The histone H3 variant centromere protein A (CENP-A) replaces H3 in nucleosomes at the centromere and is the best candidate to provide this epigenetic mark. This thesis aims to understand the features of the CENP-A nucleosome that impart its ability to mark and stabilize functional centromeres. In the first part ...


Nampt-Mediated Nad+ Homeostasis In Skeletal Muscle: Implications For Healthy Aging, David Frederick Jan 2016

Nampt-Mediated Nad+ Homeostasis In Skeletal Muscle: Implications For Healthy Aging, David Frederick

Publicly Accessible Penn Dissertations

Mammalian skeletal muscle is a highly dynamic organ capable of structural and metabolic remodeling in response to exercise demands, nutrient supply, and environmental insults. Muscle also plays a central role in the maintenance of whole-body energy balance, capable of both storing and oxidizing carbohydrate and lipid fuels. The course of natural aging leads to a gradual decline in the mass, strength, and oxidative capacity of skeletal muscle, which increases the susceptibility of the elderly to frailty and metabolic diseases, such as Type II Diabetes. Ectopic muscle lipids can also exacerbate the metabolic complications of obesity, prompting interest in new means ...


The Mitotic Genome: Accessibility And Transcriptional Control, Chris Hsiung Jan 2016

The Mitotic Genome: Accessibility And Transcriptional Control, Chris Hsiung

Publicly Accessible Penn Dissertations

Mitosis entails dramatic global alterations to genome structure and regulation, including

chromosome condensation, dissociation of the transcriptional machinery from chromosomes, and transcriptional silencing. Here I report studies that address the macromolecular accessibility of the mitotic genome and the control of transcriptional reactivation upon mitotic exit in a mammalian cell line. The results obtained from measuring the sensitivity of chromatin to DNase I cleavage by sequencing (DNase-seq) in pure mitotic cell populations demonstrate that macromolecular accessibility of the mitotic genome is widely preserved. Thus, steric hindrance from chromatin condensation is insufficient for explaining the eviction of transcription factors from mitotic chromatin ...


Haloferax Volcanii Strategies To Regulate Type Iv Pilus Dependent Adhesion And Microcolony Formation, Rianne Nicole Esquivel Jan 2016

Haloferax Volcanii Strategies To Regulate Type Iv Pilus Dependent Adhesion And Microcolony Formation, Rianne Nicole Esquivel

Publicly Accessible Penn Dissertations

Microorganisms can utilize type IV pili to initiate and maintain biofilms - microbial communities that provide protection against stressful conditions. Because environmental conditions change suddenly, microorganisms have evolved multiple mechanisms to rapidly transition from a planktonic to sessile cell state. Despite the presence of archaea alongside bacteria throughout the environment, including the human microbiome, little is known about how these organisms form and maintain biofilms. Here we use genetic, microscopic and biochemical techniques to investigate multiple strategies the model archaeon Haloferax volcanii employs to permit effective adhesion and microcolony formation, early steps in biofilm formation and maturation, as well as eventual ...


The Regulation Of Psf Activity In T Cells By Trap150 And Gsk3, Christopher Yarosh Jan 2016

The Regulation Of Psf Activity In T Cells By Trap150 And Gsk3, Christopher Yarosh

Publicly Accessible Penn Dissertations

PSF is a ubiquitously expressed and essential nuclear protein that influences many aspects of the genome maintenance and gene expression pathways. Although previous studies have identified numerous protein cofactors and nucleic acid targets of PSF, insufficient work has been done to understand how it is regulated to accomplish its various functions in a coordinated manner. Previous research in the Lynch laboratory demonstrated that, in T cells, PSF is a downstream target of the serine/threonine kinase GSK3. Phosphorylation of PSF T687 by GSK3 promotes interaction of PSF with another multifunctional nuclear factor, TRAP150. This interaction prevents PSF from binding RNA ...


Coming Full Circle: Epithelial Plasticity And The Natural History Of Metastasis, Nicole Aiello Jan 2016

Coming Full Circle: Epithelial Plasticity And The Natural History Of Metastasis, Nicole Aiello

Publicly Accessible Penn Dissertations

The primary cause of cancer-related deaths is metastasis— the spread of cancer cells to distant organs— and yet the mechanisms underlying this process remain elusive due to the difficulty in detecting early metastatic events, which are rare, stochastic and microscopic. To investigate the cellular and molecular mechanisms of metastasis, I utilized an autochthonous mouse model of pancreatic cancer (KPCY) in which all tumor cells are genetically labeled with yellow fluorescent protein (YFP). The YFP lineage label allows for the detection and isolation of disseminated tumor cells as they delaminate from epithelial structures within the primary tumor, invade into the stroma ...


Interplay Between P53 And Epigenetic Pathways In Cancer, Jiajun Zhu Jan 2016

Interplay Between P53 And Epigenetic Pathways In Cancer, Jiajun Zhu

Publicly Accessible Penn Dissertations

The human TP53 gene encodes the most potent tumor suppressor protein p53. More than half of all human cancers contain mutations in the TP53 gene, while the majority of the remaining cases involve other mechanisms to inactivate wild-type p53 function. In the first part of my dissertation research, I have explored the mechanism of suppressed wild-type p53 activity in teratocarcinoma. In the teratocarcinoma cell line NTera2, we show that wild-type p53 is mono-methylated at Lysine 370 and Lysine 382. These post-translational modifications contribute to the compromised tumor suppressive activity of p53 despite a high level of wild-type protein in NTera2 ...


Siv Infected Chimpanzees: Consequences Of Long-Term Infection And Potential Intervention Strategies, Hannah J. Barbian Jan 2016

Siv Infected Chimpanzees: Consequences Of Long-Term Infection And Potential Intervention Strategies, Hannah J. Barbian

Publicly Accessible Penn Dissertations

Simian immunodeficiency virus of chimpanzees (SIVcpz) is widespread in wild-living chimpanzees and can cause mortality and AIDS-like immunopathology. However, due to limited access to naturally infected chimpanzees, little is known about SIVcpz pathogenesis and potential intervention strategies that might be effective in captivity or in the wild. Given the central role of the intestinal microbiome in mammalian health, I asked whether gut microbial constituents could reveal any insights into SIVcpz-associated pathogenicity. I characterized the gut microbiome and virome of SIVcpz infected and uninfected chimpanzees in Gombe National Park, Tanzania. I found that SIVcpz infected chimpanzees retain a stable gut microbiome ...


Genome-Wide Approaches To Study Rna Secondary Structure, Nathan Daniel Berkowitz Jan 2016

Genome-Wide Approaches To Study Rna Secondary Structure, Nathan Daniel Berkowitz

Publicly Accessible Penn Dissertations

The central hypothesis of molecular biology depicts RNA as an intermediary conveyor of genetic information. RNA is transcribed from DNA and translated to proteins, the molecular machines of the cell. However, many RNAs do not encode protein and instead function as molecular machines themselves. The most famous examples are ribosomal RNAs and transfer RNAs, which together form the core translational machinery of the cell. Many other non-coding RNAs have been discovered including catalytic and regulatory RNAs. In many cases RNA function is tightly linked to its secondary structure, which is the collection of hydrogen bonds between complimentary RNA sequences that ...


Dna Disentangled: Roles For Sgs1 And Top3 In Rec-X Resolution And Replication Fork Restart, Mary Rebecca Glineburg Jan 2016

Dna Disentangled: Roles For Sgs1 And Top3 In Rec-X Resolution And Replication Fork Restart, Mary Rebecca Glineburg

Publicly Accessible Penn Dissertations

Homologous recombination (HR), becomes important for repair during replication where completion of DNA synthesis relies on recombination intermediate-mediated lesion bypass. For decades, Holliday Junctions (HJs) were considered the primary recombination intermediate utilized during this repair process, but increasing evidence points out two strong discrepancies: 1) X-structures, when present, are often biochemically inconsistent with being HJs, and 2) despite HR mutants being sensitive to numerous DNA damaging agents, most insults don’t result in X-structure accumulation, suggesting alternative HR pathways are at play. The Sgs1-Top3-Rmi1 (STR) complex, in Saccharomyces cerevisiae, is vital for maintaining genome integrity, and is known to resolve ...


Deciphering The Tetrad Of Epigenetic Cytosine Modifications, Monica Yun Liu Jan 2016

Deciphering The Tetrad Of Epigenetic Cytosine Modifications, Monica Yun Liu

Publicly Accessible Penn Dissertations

A tetrad of epigenetic cytosine modifications imbues the DNA code with complex, dynamic meaning. DNA methyltransferase enzymes deposit methyl marks on the 5-carbon of cytosine, forming 5-methylcytosine (mC), which generally mediates long-term, locus-specific transcriptional repression during development and reprogramming. Ten-eleven translocation (TET) family enzymes oxidize the methyl group in three steps, forming predominantly 5-hydroxymethylcytosine (hmC) but also low levels of 5-formylcytosine (fC) and 5-carboxylcytosine (caC). These additional bases likely provide pathways for erasing methylation, but they may also harbor epigenetic functions in their own right. Questions regarding how each base forms and functions drive at the fundamental biology of the ...


Mining Genomic Variants And Causal Pathways Linking Hdl And Triglycerides To Coronary Disease, Sumeet Anand Khetarpal Jan 2016

Mining Genomic Variants And Causal Pathways Linking Hdl And Triglycerides To Coronary Disease, Sumeet Anand Khetarpal

Publicly Accessible Penn Dissertations

Blood lipids are important biomarkers of risk of coronary heart disease (CHD), the leading cause of death in the world. Myriad data support a causal role of low-density lipoprotein cholesterol (LDL-C) in increasing risk of CHD. Long-standing epidemiology suggests that high-density lipoprotein cholesterol (HDL-C) may protect from disease while high triglycerides (TGs) increase CHD risk. However, the causality of HDL-C and TG to CHD remains controversial. New genetic methodologies have allowed a better look into causal pathways underlying relationships between these traits and disease. Using a combination of approaches for interrogating rare genetic variation in humans, we investigated how HDL ...


Genetic Requirement For The Rna Helicase Mov10l1 In Pirna Biogenesis, Qi Fu Jan 2016

Genetic Requirement For The Rna Helicase Mov10l1 In Pirna Biogenesis, Qi Fu

Publicly Accessible Penn Dissertations

GENETIC REQUIREMENT FOR THE RNA HELICASE MOV10L1 IN PIRNA BIOGENESIS

Qi Fu

P. Jeremy Wang

Piwi-interacting RNAs (piRNAs) are a class of small non-coding RNAs required for transposon silencing, germ cell development, and fertility in many eukaryotic species. However, many of the mechanisms underlying piRNA biogenesis have not been elucidated. Studies of MOV10L1 support its function as an RNA helicase in the processing of piRNA precursors. In this study, we elucidate the requirement for MOV10L1 RNA helicase activity in piRNA biogenesis.

To determine the requirement for MOV10L1 RNA helicase activity in piRNA biogenesis in vivo, we generated two knock-in mouse ...


Determination Of A Comprehensive Alternative Splicing Regulatory Network And The Combinatorial Regulation By Key Factors During The Epithelial To Mesenchymal Transition, Yueqin Yang Jan 2016

Determination Of A Comprehensive Alternative Splicing Regulatory Network And The Combinatorial Regulation By Key Factors During The Epithelial To Mesenchymal Transition, Yueqin Yang

Publicly Accessible Penn Dissertations

The epithelial to mesenchymal transition (EMT) is a process by which epithelial cells transdifferentiate into mesenchymal cells. It is essential for embryonic development and implicated in cancer metastasis. While the transcriptional regulation of EMT has been well-studied, the role of post-transcriptional regulation, particularly alternative splicing (AS) regulation in EMT, remains relatively uncharacterized. We previously showed that the epithelial cell-type-specific proteins ESRP1 and ESRP2 are important for regulation of many AS events that altered during EMT. However, the contributions of the ESRPs and other splicing regulators to the splicing regulatory network in EMT require further investigation.

In the first part of ...


Identification Of Novel Molecular-Genetic Pathways Regulating The Development Of Subpallial Derivatives, David Tischfield Jan 2016

Identification Of Novel Molecular-Genetic Pathways Regulating The Development Of Subpallial Derivatives, David Tischfield

Publicly Accessible Penn Dissertations

The embryonic subpallium produces many different neuronal cell types present throughout the adult telencephalon, including striatal medium spiny neurons (MSN) and cortical interneurons. Dysfunction of either cell type leads to neurological and psychiatric disorders including schizophrenia, epilepsy, and Tourette’s syndrome. Thus, understanding the molecular pathways that regulate their development and function has important implications for understanding disease pathogenesis. This work describes novel methods and genetic factors that expand our ability to characterize the development and function of two major subpallial derivatives: cortical interneurons and striatal MSN. The first part of this thesis characterizes a novel enrichment method for producing ...


Insights Into Terminal Erythropoiesis Influenced By Human Genetic Variation, Elizabeth Traxler Jan 2016

Insights Into Terminal Erythropoiesis Influenced By Human Genetic Variation, Elizabeth Traxler

Publicly Accessible Penn Dissertations

Red blood cells (RBCs) carry hemoglobin, enabling delivery of oxygen to all tissues of the body. They are the products of a highly specialized differentiation process that begins with a hematopoietic stem cell and results in an enucleated, biconcave RBC. This thesis is focused on the use of human genetic studies to gain a better understanding of the molecular processes occurring during terminal erythroid differentiation. We studied the regulation and roles of two erythroid-restricted genes, Trim58 and Hemoglobin Gamma Chain (HBG1 and HBG2, γ-globin), by using a combination of loss-of-function techniques, including RNA-interference-mediated gene suppression, a mutant mouse model, and ...


Multiple Roles Of Ret Signaling In Mechanosensory Neuron Development, Michael Scott Fleming Jan 2016

Multiple Roles Of Ret Signaling In Mechanosensory Neuron Development, Michael Scott Fleming

Publicly Accessible Penn Dissertations

Somatosensation is critical for interaction with the surrounding environment. Somatosensory stimuli are detected by primary somatosensory neurons of the dorsal root ganglia and trigeminal ganglia, which detect distinct classes of stimuli, such as temperature, pain, and pressure. In Chapters 2 and 3 of this thesis, we focus on rapidly adapting low-threshold mechanoreceptors (RALTMRs), which mediate the detection of light touch. RALTMRs are molecularly defined by the early embryonic expression of the receptor tyrosine kinase Ret. Ret is required for the development of central axonal projections of RALTMRs into the dorsal spinal cord. RET responds to the glial cell line-derived family ...


Epigenetic Regulation Of The Dlk1-Meg3 Imprinted Locus In Human Islets, Vasumathi Kameswaran Jan 2016

Epigenetic Regulation Of The Dlk1-Meg3 Imprinted Locus In Human Islets, Vasumathi Kameswaran

Publicly Accessible Penn Dissertations

Type 2 diabetes mellitus (T2DM) is a complex metabolic disease characterized by inadequate insulin secretion by the pancreatic β-cell in response to increased blood glucose levels. Despite compelling evidence that T2DM has a high rate of familial aggregation, known genetic risk variants account for less than 10% of the observed heritability. Consequently, post-transcriptional regulators of gene expression, including microRNAs and other noncoding RNAs, have been implicated in the etiology of T2DM, in part due to their ability to simultaneously regulate the expression of hundreds of targets.

To determine if microRNAs are involved in the pathogenesis of human T2DM, I sequenced ...


Defining Mechanisms Of Autoimmunity In Pemphigus Vulgaris, Michael Jeffrey Tejada Cho Jan 2016

Defining Mechanisms Of Autoimmunity In Pemphigus Vulgaris, Michael Jeffrey Tejada Cho

Publicly Accessible Penn Dissertations

A prominent question in the field of autoimmunity is how these diseases arise. Currently, the etiologies of many autoimmune diseases remain unclear. The work described here provides insight into this question in the context of pemphigus vulgaris (PV), a prototypic autoimmune disease characterized by serum autoantibodies to desmoglein (Dsg) 3. We utilize a combination of both antibody phage display and heterohybridoma to probe the anti-Dsg3 antibody repertoires of patients with PV. We first address whether a cohort of four patients with active disease demonstrate any shared characteristics in their anti-Dsg3 antibody repertoires (Chapter 2), and if so, why. We find ...


Contextual Insights Into The Rett Syndrome Transcriptome, Brian Scott Roosevelt Johnson Jan 2016

Contextual Insights Into The Rett Syndrome Transcriptome, Brian Scott Roosevelt Johnson

Publicly Accessible Penn Dissertations

Mutations in MECP2 are responsible for Rett syndrome (RTT), a severe X-linked neurological disorder characterized by loss of developmental milestones, intellectual disability and motor impairments. However, molecular insight into how these mutations affect the neuronal transcriptiome, disrupt neuronal function and contribute to RTT is impeded by the cellular heterogeneity of the mammalian brain. A comparison between gene expression changes in the striatum, hypothalamus, and cerebellum of MeCP2-null mice revealed that gene expression changes are distinct between different brain regions, which suggests that MeCP2 function should be understood in a cell type-dependent context. To accomplish this task, I generated and phenotypically ...