Molecular Biology Commons^™

Jab1 Negatively Regulates Pten And Promotes Resistance To Trastuzumab In Her2-Positive Breast Cancer, Thuy T. Vu

Dissertations & Theses (Open Access)

HER2-positive breast cancer, which is characterized by the over-expression of the HER2 onco-protein, accounts for approximately 20% of all breast cancer cases. Trastuzumab (Herceptin), the first targeted therapy approved for HER2-positive disease, potently prevents the activation of signaling pathways downstream of HER2 and significantly improves patients’ outcomes. However, resistance to trastuzumab is inevitable; such resistance can occur through reduced expression of PTEN protein.

Jab1 is over-expressed in 50% of primary cancers and 90% of metastatic tumors. Our lab previously showed that depletion of Jab1 in combination with trastuzumab treatment up-regulated PTEN in mouse xenografts refractory to trastuzumab. PTEN was not …

Swarna Ramaswamy_Thesis, Swarna S. Ramaswamy

Dissertations & Theses (Open Access)

STRUCTURAL INVESTIGATIONS OF LIGAND GATED ION CHANNELS

Swarna Ramaswamy, B.S

Advisor: Vasanthi Jayaraman, Ph.D.

Ion channels form an integral part of membrane proteins. In the nervous system including the central and the peripheral nervous system, ligand gated ion channels form a very important part of intercellular communications. They receive chemical signals and convert them to electrical signal, mainly by allowing ion passage across the cell membrane. Ion passage also translates into downstream signaling events. Faithful translation of these signals and transmittance is crucial for several physiological functions, implying that irregular ion channel function could lead to serious consequences.

This thesis …

Novel Posttranslational Modification In Lkb1 Activation And Function, Szu-Wei Lee

Dissertations & Theses (Open Access)

Cancer cells display dramatic alterations in cellular metabolism to meet their needs of increased growth and proliferation. In the last decade, cancer research has brought these pathways into focus, and one emerging issue that has come to attention is that many oncogenes and tumor-suppressors are intimately linked to metabolic regulation (Jones and Thompson, 2009). One of the key tumor-suppressors involved in metabolism is Liver Kinase B1 (LKB1). LKB1 is the major upstream kinase of the evolutionarily conserved metabolic sensor—AMP-activated protein kinase (AMPK). Activation of the LKB1/AMPK pathway provides a survival advantage for cells under energy stress. LKB1 forms a heterotrimeric …

Roles For B-Raf Kinase In The Specific Regulation Of Α4Β1 Integrin In T Cells, Wells S. Brown

Dissertations & Theses (Open Access)

The regulation of integrin-mediated adhesion is of vital importance to adaptive and innate immunity. Integrins are versatile proteins and mediate T cell migration and trafficking by binding to ECM or other cells, as well as initiating intracellular signaling cascades promoting survival or activation. The mitogen activated-protein kinase (MAPK) pathway is known to be downstream from integrins and regulate survival, differentiation, and motility. However, secondary roles for canonical MAPK pathway members are being discovered. We show chemical inhibition of RAF by Sorafenib or shRNA-mediated knockdown of B-Raf reduces T cell resistance to shear stress to α4β1 integrin ligands vascular cell adhesion …

Pi3k- And Mtor-Dependent Mechanisms Of Lapatinib Resistance And Resulting Therapeutic Opportunities, Samuel Brady

Dissertations & Theses (Open Access)

Breast cancers with HER2 amplification represent 20-25% of breast cancer cases and are frequently responsive to the HER2 kinase inhibitor lapatinib, but generally for only short duration. We aimed to understand how breast cancers with HER2 amplification become resistant to lapatinib, in order to identify potential therapies that can overcome lapatinib resistance. To establish lapatinib resistance models we treated three HER2+ breast cancer cell lines with lapatinib for several months until they became lapatinib-resistant. We then compared lapatinib-sensitive (parental) cells with their lapatinib-resistant (LapR) counterparts to identify changes conferring lapatinib resistance. We found that activation of PI3K, specifically the p110α …

Egfr Modulates Microrna Maturation In Response To Hypoxia Through Phosphorylation Of Argonaute2, Jia Shen

Dissertations & Theses (Open Access)

MicroRNAs (miRNAs) are generated by two-step processing to yield small RNAs that negatively regulate target gene expression at posttranscriptional level. Deregulation of miRNAs has been linked to diverse pathological processes, including cancer. Recent studies have also implicated miRNAs in regulatory roles to cope with a spectrum of stresses, such as hypoxia, which is frequently encountered in the poorly angiogenic core of a solid tumor. However, the upstream regulators of miRNA biogenesis machineries remain obscure, raising the question of how tumor cells efficiently coordinate and impose specificity on miRNA expression and function in response to stresses. Here, we show that EGFR, …

Energy Stress Causes Chaperones To Assemble Into Cytoplasmic Complexes, Kimberly J. Cope

Dissertations & Theses (Open Access)

The majority of proteins require molecular chaperones to assist their folding into tertiary and quaternary structures. Certain stresses can compromise the weak hydrophobic forces responsible for these structures and lead to protein unfolding, misfolding, and aggregation. Aggregates of proteins are hallmarks of devastating diseases such as Alzheimer’s, Parkinson’s, and Huntington’s diseases. Fortunately, bacteria, plants, and fungi have a potent disaggregase, named Hsp104 in Saccharomyces cerevisiae. Recently, heat-induced aggregates, termed Q-bodies, were found to contain three molecular chaperones: Hsp70, Hsp104, and Hsp42. Their coalescence from small puncta into larger inclusions required Hsp104. During glucose deprivation, a stress that isn’t known to …

Functional Analysis Of Cytosolic Hsp70 Nucleotide Exchange Factor Networks In Yeast, Jennifer Lynn Abrams

Dissertations & Theses (Open Access)

The Hsp70 class of molecular chaperones play critical roles in protein homeostasis via an ATP-dependent folding cycle. Cytosolic Hsp70s in the budding yeast Saccharomyces cerevisiae, Ssa and Ssb, interact with up to three distinct nucleotide exchange factors (NEFs) homologous to human counterparts; Sse1/Sse2/HSP110, Fes1/HspBP1, and Snl1/Bag1. In an effort to understand the differential functional contributions of the cytosolic NEFs to protein homeostasis (“proteostasis”), I carried out comparative genetic, biochemical and cell biological analyses. For these studies, I developed protocols to monitor protein disaggregation and reactivation in a near real-time coupled assay that revealed the importance of aggregate dynamics in the …

Diabetes And Obesity Induce Transcriptomic And Metabolomic Changes Enhancing Pancreatic Cancer Aggressiveness, Guermarie Velázquez Torres

Dissertations & Theses (Open Access)

Pancreatic cancer is one of the most aggressive types of cancer, with poor prognosis that lacks effective diagnostic markers and therapies. It is expected that in 2014 the incidence and the mortality of pancreatic cancer in the United States will be 46,420 and 39,590 respectively. Diabetes and obesity are modifiable risk factors associated with accelerated pancreatic carcinogenesis and tumor progression, but the biological mechanisms are not completely understood. The purpose of this study is to demonstrate direct evidence for the mechanisms mediating these epidemiologic phenomena. Our hypothesis is that obesity and diabetes mellitus type 2 (DM2) accelerate pancreatic cancer and …

The Regulation Of Microrna Biogenesis By Ribosome-Interacting Proteins, Brian Pickering

Dissertations & Theses (Open Access)

MicroRNA (miRNA) are small, non-coding RNAs that affect gene expression through degradation of complementary mRNA targets or inhibition of translation. As they affect approximately 50% of all cellular processes, miRNA are tightly regulated by the cell through transcriptional and post-transcriptional mechanisms. Transcribed miRNA are capped and polyadenylated (referred to as pri-miRNA) which are cleaved by Drosha and DGCR8 to generate 60-90 nucleotide precursor miRNA. The precursors are cleaved again by Dicer and loaded into the RNA-induced silencing complex (RISC) of which Argonaute 2 is the functional component. Many of the proteins involved in miRNA biogenesis share a common role in …

Characterization Of Ftsa-Ftsn Interaction During Escherichia Coli Cell Division, Kimberly.Busiek@Gmail.Com K. Busiek

Dissertations & Theses (Open Access)

Division of a bacterial cell into two equal daughter cells requires precise assembly and constriction of the division machinery, or divisome. The Escherichia coli divisome includes nearly a dozen essential cell division proteins that assemble at midcell between segregating sister chromosomes. FtsZ, a homolog of eukaryotic tubulin, is the first essential cell division protein to localize at midcell where it polymerizes into a ring-shaped scaffold (Z ring). Establishment of the Z ring is required for recruitment of downstream cell division proteins including FtsA, a cytoplasmic protein that tethers the Z ring to the inner membrane. Following localization of FtsA and …