Medical Sciences Commons^™

Tumor-Resident Lactobacillus Iners Confer Chemoradiation Resistance Through Lactate-Induced Metabolic Rewiring, Lauren E. Colbert, Molly B. El Alam, Rui Wang, Tatiana Karpinets, David Lo, Erica J. Lynn, Timothy A. Harris, Jacob H. Elnaggar, Kyoko Yoshida-Court, Katarina Tomasic, Julianna K. Bronk, Julie Sammouri, Ananta V. Yanamandra, Adilene V. Olvera, Lily G. Carlin, Travis Sims, Andrea Y. Delgado Medrano, Tatiana Cisneros Napravnik, Madison O'Hara, Daniel Lin, Chike O. Abana, Hannah X. Li, Patricia J. Eifel, Anuja Jhingran, Melissa Joyner, Lilie Lin, Lois M. Ramondetta, Andrew M. Futreal

School of Medicine Faculty Publications

Tumor microbiota can produce active metabolites that affect cancer and immune cell signaling, metabolism, and proliferation. Here, we explore tumor and gut microbiome features that affect chemoradiation response in patients with cervical cancer using a combined approach of deep microbiome sequencing, targeted bacterial culture, and in vitro assays. We identify that an obligate L-lactate-producing lactic acid bacterium found in tumors, Lactobacillus iners, is associated with decreased survival in patients, induces chemotherapy and radiation resistance in cervical cancer cells, and leads to metabolic rewiring, or alterations in multiple metabolic pathways, in tumors. Genomically similar L-lactate-producing lactic acid bacteria commensal to other …

A Cancer Ubiquitome Landscape Identifies Metabolic Reprogramming As Target Of Parkin Tumor Suppression, Ekta Agarwal, Aaron R Goldman, Hsin-Yao Tang, Andrew V Kossenkov, Jagadish C Ghosh, Lucia Languino, Valentina Vaira, David W Speicher, Dario C Altieri

Department of Cancer Biology Faculty Papers

Changes in metabolism that affect mitochondrial and glycolytic networks are hallmarks of cancer, but their impact in disease is still elusive. Using global proteomics and ubiquitome screens, we now show that Parkin, an E3 ubiquitin ligase and key effector of mitophagy altered in Parkinson's disease, shuts off mitochondrial dynamics and inhibits the non-oxidative phase of the pentose phosphate pathway. This blocks tumor cell movements, creates metabolic and oxidative stress, and inhibits primary and metastatic tumor growth. Uniformly down-regulated in cancer patients, Parkin tumor suppression requires its E3 ligase function, is reversed by antioxidants, and is independent of mitophagy. These data …

Apoe And Alzheimer’S Disease: Neuroimaging Of Metabolic And Cerebrovascular Dysfunction, Jason A. Brandon, Brandon C. Farmer, Holden C. Williams, Lance A. Johnson

Physiology Faculty Publications

Apolipoprotein E4 (ApoE4) is the strongest genetic risk factor for late onset Alzheimer’s Disease (AD), and is associated with impairments in cerebral metabolism and cerebrovascular function. A substantial body of literature now points to E4 as a driver of multiple impairments seen in AD, including blunted brain insulin signaling, mismanagement of brain cholesterol and fatty acids, reductions in blood brain barrier (BBB) integrity, and decreased cerebral glucose uptake. Various neuroimaging techniques, in particular positron emission topography (PET) and magnetic resonance imaging (MRI), have been instrumental in characterizing these metabolic and vascular deficits associated with this important AD risk factor. In …

Metronidazole Metabolism In Neonates And The Interplay Between Ontogeny And Genetic Variation., Laura A. Wang, Daniel Gonzalez, J Steven Leeder, Rachel F. Tyndale, Robin E. Pearce, Daniel K. Benjamin, Gregory L. Kearns, Michael Cohen-Wolkowiez, Best Pharmaceuticals For Children Act-Pediatric Trials Network Steering Committee

Manuscripts, Articles, Book Chapters and Other Papers

No abstract provided.

Cyclin-Dependent Kinase Inhibitor P1446a Induces Apoptosis In A Jnk/P38 Mapk-Dependent Manner In Chronic Lymphocytic Leukemia B-Cells, Cody Paiva, J. Claire Godbersen, Ryan S. Soderquist, Taylor Rowland, Sumner Kilmarx

Dartmouth Scholarship

CDK (cyclin-dependent kinase) inhibitors have shown remarkable activity in CLL, where its efficacy has been linked to inhibition of the transcriptional CDKs (7 and 9) and deregulation of RNA polymerase and short-lived pro-survival proteins such as MCL1. Furthermore, ER (endoplasmic reticulum) stress has been implicated in CDK inhibition in CLL. Here we conducted a pre-clinical study of a novel orally active kinase inhibitor P1446A in CLL B-cells. P1446A inhibited CDKs at nanomolar concentrations and induced rapid apoptosis of CLL cells in vitro, irrespective of chromosomal abnormalities or IGHV mutational status. Apoptosis preceded inactivation of RNA polymerase, and was accompanied by …

Systems Level Analysis Of Systemic Sclerosis Shows A Network Of Immune And Profibrotic Pathways Connected With Genetic Polymorphisms, J. Matthew Mahoney, Jaclyn Taroni, Viktor Martyanov, Tammara A. A. Wood, Casey S. Greene, Patricia A. Pioli, Monique E. Hinchcliff, Michael L. Whitfield

Dartmouth Scholarship

Systemic sclerosis (SSc) is a rare systemic autoimmune disease characterized by skin and organ fibrosis. The pathogenesis of SSc and its progression are poorly understood. The SSc intrinsic gene expression subsets (inflammatory, fibroproliferative, normal-like, and limited) are observed in multiple clinical cohorts of patients with SSc. Analysis of longitudinal skin biopsies suggests that a patient's subset assignment is stable over 6-12 months. Genetically, SSc is multi-factorial with many genetic risk loci for SSc generally and for specific clinical manifestations. Here we identify the genes consistently associated with the intrinsic subsets across three independent cohorts, show the relationship between these genes …

Syndecan 4 Is Required For Endothelial Alignment In Flow And Atheroprotective Signaling, Nicolas Baeyens, Mary Jo Mulligan-Kehoe, Federico Corti, David D. Simon, Tyler D. Ross, John M. Rhodes, Thomas Z. Wang

Dartmouth Scholarship

Atherosclerotic plaque localization correlates with regions of disturbed flow in which endothelial cells (ECs) align poorly, whereas sustained laminar flow correlates with cell alignment in the direction of flow and resistance to atherosclerosis. We now report that in hypercholesterolemic mice, deletion of syndecan 4 (S4−/−) drastically increased atherosclerotic plaque burden with the appearance of plaque in normally resistant locations. Strikingly, ECs from the thoracic aortas of S4−/− mice were poorly aligned in the direction of the flow. Depletion of S4 in human umbilical vein endothelial cells (HUVECs) using shRNA also inhibited flow-induced alignment in vitro, which was rescued by re-expression …

E2f4 Regulatory Program Predicts Patient Survival Prognosis In Breast Cancer, Sari S. Khaleel, Erik H. Andrews, Matthew Ung, James Direnzo, Chao Chung

Dartmouth Scholarship

Genetic and molecular signatures have been incorporated into cancer prognosis prediction and treatment decisions with good success over the past decade. Clinically, these signatures are usually used in early-stage cancers to evaluate whether they require adjuvant therapy following surgical resection. A molecular signature that is prognostic across more clinical contexts would be a useful addition to current signatures. We defined a signature for the ubiquitous tissue factor, E2F4, based on its shared target genes in multiple tissues. These target genes were identified by chromatin immunoprecipitation sequencing (ChIP-seq) experiments using a probabilistic method. We then computationally calculated the regulatory activity score …

The Toxoplasma Gondii Cyst Wall Protein Cst1 Is Critical For Cyst Wall Integrity And Promotes Bradyzoite Persistence, Tadakimi Tomita, David J. Bzik, Yan Fen Ma, Barbara A. Fox

Dartmouth Scholarship

Toxoplasma gondii infects up to one third of the world's population. A key to the success of T. gondii as a parasite is its ability to persist for the life of its host as bradyzoites within tissue cysts. The glycosylated cyst wall is the key structural feature that facilitates persistence and oral transmission of this parasite. Because most of the antibodies and reagents that recognize the cyst wall recognize carbohydrates, identification of the components of the cyst wall has been technically challenging. We have identified CST1 (TGME49_064660) as a 250 kDa SRS (SAG1 related sequence) domain protein with a large …

Interactions Of Peptide Triazole Thiols With Env Gp120 Induce Irreversible Breakdown And Inactivation Of Hiv-1 Virions, Arangassery Bastian, Mark Contarino, Lauren D. Bailey, Rachna Aneja, Diogo Rodrigo Magalhaes Moreira, Kevin Freedman, Karyn Mcfadden, Caitlin Duffy, Ali Emileh

Dartmouth Scholarship

Background: We examined the underlying mechanism of action of the peptide triazole thiol, KR13 that has been shown previously to specifically bind gp120, block cell receptor site interactions and potently inhibit HIV-1 infectivity.

Results: KR13, the sulfhydryl blocked KR13b and its parent non-sulfhydryl peptide triazole, HNG156, induced gp120 shedding but only KR13 induced p24 capsid protein release. The resulting virion post virolysis had an altered morphology, contained no gp120, but retained gp41 that bound to neutralizing gp41 antibodies. Remarkably, HIV-1 p24 release by KR13 was inhibited by enfuvirtide, which blocks formation of the gp41 6-helix bundle during membrane fusion, while …

Id4 Deficiency Attenuates Prostate Development And Promotes Pin-Like Lesions By Regulating Androgen Receptor Activity And Expression Of Nkx3.1 And Pten, Pankaj Sharma, Ashley Knowell, Swathi Chinaranagari, Shravan Komaragiri, Peri Nagappan, Divya Patel, Mathew C. Havrda, Jaideep Chaudhary

Dartmouth Scholarship

Background: Inhibitor of differentiation 4 (Id4), a member of the helix-loop-helix family of transcriptional regulators has emerged as a tumor suppressor in prostate cancer. Id4 is expressed in the normal prostate where its expression is also regulated by androgens. In this study we investigated the effect of loss of Id4 (Id4-/-) on adult prostate morphology. Methods: Histological analysis was performed on prostates from 6-8 weeks old Id4-/-, Id4+/- and Id4+/+ mice. Expression of Id1, Sox9, Myc, androgen receptor, Akt, p-Akt, Pten and Nkx3.1 was investigated by immunohistochemistry. Androgen receptor binding on NKX3.1 promoter was studied by chromatin immuno-precipitation. Id4 was …

Pilot Study Of Cyp2b6 Genetic Variation To Explore The Contribution Of Nitrosamine Activation To Lung Carcinogenesis, Catherine Wassenaar, Qiong Dong, Christopher Amos, Margaret Spitz, Rachel F. Tyndale

Dartmouth Scholarship

We explored the contribution of nitrosamine metabolism to lung cancer in a pilot investigation of genetic variation in CYP2B6, a high-affinity enzymatic activator of tobacco-specific nitrosamines with a negligible role in nicotine metabolism. Previously we found that variation in CYP2A6 and CHRNA5-CHRNA3-CHRNB4 combined to increase lung cancer risk in a case-control study in European American ever-smokers (n = 860). However, these genes are involved in the pharmacology of both nicotine, through which they alter smoking behaviours, and carcinogenic nitrosamines. Herein, we separated participants by CYP2B6 genotype into a high- vs. low-risk group (*1/*1 + *1/*6 vs. *6/*6). Odds ratios estimated …

Inhibition Of The Host Translation Shutoff Response By Herpes Simplex Virus 1 Triggers Nuclear Envelope-Derived Autophagy, Kerstin Radtke, Luc English, Christiane Rondeau, David Leib

Dartmouth Scholarship

Macroautophagy is a cellular pathway that degrades intracellular pathogens and contributes to antigen presentation. Herpes simplex virus 1 (HSV-1) infection triggers both macroautophagy and an additional form of autophagy that uses the nuclear envelope as a source of membrane. The present study constitutes the first in-depth analysis of nuclear envelope-derived autophagy (NEDA). We established LC3a as a marker that allowed us to distinguish between NEDA and macroautophagy in both immunofluorescence and flow cytometry. NEDA was observed in many different cell types, indicating that it is a general response to HSV-1 infection. This autophagic pathway is known to depend on the …

Triterpenoid Modulation Of Il-17 And Nrf-2 Expression Ameliorates Neuroinflammation And Promotes Remyelination In Autoimmune Encephalomyelitis, Tej K. Pareek, Abdelmadjid Belkadi, Sashi Kesavapany, Anita Zaremba, Sook L. Loh, Lianhua Bai, Mark L. Cohen, Colin Meyer, Karen T. Liby, Robert H. Miller, Michael B. Sporn, John J. Letterio

Dartmouth Scholarship

Inflammatory cytokines and endogenous anti-oxidants are variables affecting disease progression in multiple sclerosis (MS). Here we demonstrate the dual capacity of triterpenoids to simultaneously repress production of IL-17 and other pro-inflammatory mediators while exerting neuroprotective effects directly through Nrf2-dependent induction of anti-oxidant genes. Derivatives of the natural triterpene oleanolic acid, namely CDDO-trifluoroethyl-amide (CDDO-TFEA), completely suppressed disease in a murine model of MS, experimental autoimmune encephalomyelitis (EAE), by inhibiting Th1 and Th17 mRNA and cytokine production. Encephalitogenic T cells recovered from treated mice were hypo-responsive to myelin antigen and failed to adoptively transfer the disease. Microarray analyses showed significant suppression of …

Variations In Mre11/Rad50/Nbs1 Status And Dna Damage-Induced S-Phase Arrest In The Cell Lines Of The Nci60 Panel, Kristen M. K. Garner, Alan Eastman

Dartmouth Scholarship

The Mre11/Rad50/Nbs1 (MRN) complex is a regulator of cell cycle checkpoints and DNA repair. Defects in MRN can lead to defective S-phase arrest when cells are damaged. Such defects may elicit sensitivity to selected drugs providing a chemical synthetic lethal interaction that could be used to target therapy to tumors with these defects. The goal of this study was to identify these defects in the NCI60 panel of cell lines and identify compounds that might elicit selective cytotoxicity.

Proliferation Of Aneuploid Human Cells Is Limited By A P53-Dependent Mechanism, Sarah L. Thompson, Duane A. Compton

Dartmouth Scholarship

Most solid tumors are aneuploid, and it has been proposed that aneuploidy is the consequence of an elevated rate of chromosome missegregation in a process called chromosomal instability (CIN). However, the relationship of aneuploidy and CIN is unclear because the proliferation of cultured diploid cells is compromised by chromosome missegregation. The mechanism for this intolerance of nondiploid genomes is unknown. In this study, we show that in otherwise diploid human cells, chromosome missegregation causes a cell cycle delay with nuclear accumulation of the tumor suppressor p53 and the cyclin kinase inhibitor p21. Deletion of the p53 gene permits the accumulation …

Polysorbate 80 Inhibition Of Pseudomonas Aeruginosa Biofilm Formation And Its Cleavage By The Secreted Lipase Lipa, C M. Toutain-Kidd, S C. Kadivar, C T. Bramante, S A. Bobin, Michael E. Zegans

Dartmouth Scholarship

Surface-associated bacterial communities known as biofilms are an important source of nosocomial infections. Microorganisms such as Pseudomonas aeruginosa can colonize the abiotic surfaces of medical implants, leading to chronic infections that are difficult to eradicate. Our study demonstrates that polysorbate 80 (PS80), a surfactant commonly added to food and medicines, is able to inhibit biofilm formation by P. aeruginosa on a variety of surfaces, including contact lenses.

Paracrine Sonic Hedgehog Signalling By Prostate Cancer Cells Induces Osteoblast Differentiation, Samantha M Zunich, Taneka Douglas, Maria Valdovinos, Tiffany Chang

Dartmouth Scholarship

Sonic hedgehog (Shh) and components of its signalling pathway have been identified in human prostate carcinoma and increased levels of their expression appear to correlate with disease progression and metastasis. The mechanism through which Shh signalling could promote metastasis in bone, the most common site for prostate carcinoma metastasis, has not yet been investigated. The present study determined the effect of Shh signalling between prostate cancer cells and pre-osteoblasts on osteoblast differentiation, a requisite process for new bone formation that characterizes prostate carcinoma metastasis.

Corr4a And Vrt325 Do Not Reduce The Inflammatory Response To P. Aeruginosa In Human Cystic Fibrosis Airway Epithelial Cells, Laleh Talebian, Bonita Coutermarsh, Jacqueline Y. Channon, Bruce A. Stanton

Dartmouth Scholarship

P. aeruginosa chronically colonizes the lung in CF patients and elicits a proinflammatory response. Excessive secretion of IL-6 and IL-8 by CF airway cells in response to P. aeruginosa infection in the CF airway is though to contribute to lung injury. Accordingly, the goal of this study was to test the hypothesis that Corr4a and VRT325, investigational compounds that increase ΔF508-CFTR mediated Cl⁻ secretion in human CF airway cells, reduce the pro-inflammatory response to P. aeruginosa.

The Nestin Progenitor Lineage Is The Compartment Of Origin For Pancreatic Intraepithelial Neoplasia, Catherine Carriere, Elliot S. Seeley, Tobias Goetze, Daniel S. Longnecker, Murray Korc

Dartmouth Scholarship

To determine the cell compartment in which initial oncogenic mutations occur in pancreatic ductal adenocarcinoma (PDAC), we generated a mouse model in which endogenous expression of mutated Kras (Kras(G12D)) was initially directed to a population of pancreatic exocrine progenitors characterized by the expression of Nestin. Targeting of oncogenic Kras to such a restricted cell compartment was sufficient for the formation of pancreatic intraepithelial neoplasias (PanINs), putative precursors to PDAC. PanINs appeared with the same grade and frequency as observed when Kras(G12D) was targeted to the whole pancreas by a Pdx1-driven Cre recombinase strategy. Thus, the Nestin cell lineage is highly …

Transgenic Cyclin E Triggers Dysplasia And Multiple Pulmonary Adenocarcinomas, Yan Ma, Steven Fiering, Candice Black, Xi Liu, Ziqiang Yuan, Vincent A. Memoli, David J. Robbins, Heather A. Bentley, Gregory J. Tsongalis, Eugene Demidenko, Sarah J. Freemantle, Ethan Dmitrovsky

Dartmouth Scholarship

Cyclin E is a critical G(1)-S cell cycle regulator aberrantly expressed in bronchial premalignancy and lung cancer. Cyclin E expression negatively affects lung cancer prognosis. Its role in lung carcinogenesis was explored. Retroviral cyclin E transduction promoted pulmonary epithelial cell growth, and small interfering RNA targeting of cyclin E repressed this growth. Murine transgenic lines were engineered to mimic aberrant cyclin E expression in the lung. Wild-type and proteasome degradation-resistant human cyclin E transgenic lines were independently driven by the human surfactant C (SP-C) promoter. Chromosome instability (CIN), pulmonary dysplasia, sonic hedgehog (Shh) pathway activation, adenocarcinomas, and metastases occurred. Notably, …

Cdx4 Dysregulates Hox Gene Expression And Generates Acute Myeloid Leukemia Alone And In Cooperation With Meis1a In A Murine Model, Dimple Bansal, Claudia Scholl, Stefan Frohling, Elizabeth Mcdowell, Benjamin H. Lee, Konstanze Döhner, Patricia Ernst

Dartmouth Scholarship

HOX genes have emerged as critical effectors of leukemogenesis, but the mechanisms that regulate their expression in leukemia are not well understood. Recent data suggest that the caudal homeobox transcription factors CDX1, CDX2, and CDX4, developmental regulators of HOX gene expression, may contribute to HOX gene dysregulation in leukemia. We report here that CDX4 is expressed normally in early hematopoietic progenitors and is expressed aberrantly in approximately 25% of acute myeloid leukemia (AML) patient samples. Cdx4 regulates Hox gene expression in the adult murine hematopoietic system and dysregulates Hox genes that are implicated in leukemogenesis. Furthermore, bone marrow progenitors that …

Innate Antiviral Response Targets Hiv-1 Release By The Induction Of Ubiquitin-Like Protein Isg15, Atsushi Okumura, Gengshi Lu, Ian Pitha-Rowe, Paula M. Pitha

Dartmouth Scholarship

The goal of this study was to elucidate the molecular mechanism by which type I IFN inhibits assembly and release of HIV-1 virions. Our study revealed that the IFN-induced ubiquitin-like protein ISG15 mimics the IFN effect and inhibits release of HIV-1 virions without having any effect on the synthesis of HIV-1 proteins in the cells. ISG15 expression specifically inhibited ubiquitination of Gag and Tsg101 and disrupted the interaction of the Gag L domain with Tsg101, but conjugation of ISG15 to Gag or Tsg101 was not detected. The inhibition of Gag-Tsg101 interaction was also detected in HIV-1 infected, IFN-treated cells. Elimination …

Growth Factor–Induced Shedding Of Syndecan-1 Confers Glypican-1 Dependence On Mitogenic Responses Of Cancer Cells, Kan Ding, Martha Lopez-Burks, José A. Sánchez-Duran, Murray Korc, Arthur D. Lander

Dartmouth Scholarship

The cell surface heparan sulfate proteoglycan (HSPG) glypican-1 is up-regulated by pancreatic and breast cancer cells, and its removal renders such cells insensitive to many growth factors. We sought to explain why the cell surface HSPG syndecan-1, which is also up-regulated by these cells and is a known growth factor coreceptor, does not compensate for glypican-1 loss. We show that the initial responses of these cells to the growth factor FGF2 are not glypican dependent, but they become so over time as FGF2 induces shedding of syndecan-1. Manipulations that retain syndecan-1 on the cell surface make long-term FGF2 responses glypican …

A Human T-Cell Lymphotropic Virus Type 1 Enhancer Of Myc Transforming Potential Stabilizes Myc-Tip60 Transcriptional Interactions, Soumya Awasthi, Anima Sharma, Kasuen Wong, Junyu Zhang, Elizabeth F. Matlock, Lowery Rogers, Pamela Motloch, Shigeki Takemoto, Hirokuni Taguchi, Michael D. Cole

Dartmouth Scholarship

The human T-cell lymphotropic virus type 1 (HTLV-1) infects and transforms CD4+ lymphocytes and causes adult T-cell leukemia/lymphoma (ATLL), an aggressive lymphoproliferative disease that is often fatal. Here, we demonstrate that the HTLV-1 pX splice-variant p30II markedly enhances the transforming potential of Myc and transcriptionally activates the human cyclin D2 promoter, dependent upon its conserved Myc-responsive E-box enhancer elements, which are associated with increased S-phase entry and multinucleation. Enhancement of c-Myc transforming activity by HTLV-1 p30II is dependent upon the transcriptional coactivators, transforming transcriptional activator protein/p434 and TIP60, and it requires TIP60 histone acetyltransferase (HAT) activity and correlates with the …

The Tumor Suppressor Lkb1 Kinase Directly Activates Amp-Activated Kinase And Regulates Apoptosis In Response To Energy Stress, Reuben J. Shaw, Monica Kosmatka, Nabeel Bardeesy, Rebecca L. Hurley, Lee A. Witters, Ronald A. Depinho, Lewis C. Cantley

Dartmouth Scholarship

AMP-activated protein kinase (AMPK) is a highly conserved sensor of cellular energy status found in all eukaryotic cells. AMPK is activated by stimuli that increase the cellular AMP/ATP ratio. Essential to activation of AMPK is its phosphorylation at Thr-172 by an upstream kinase, AMPKK, whose identity in mammalian cells has remained elusive. Here we present biochemical and genetic evidence indicating that the LKB1 serine/threonine kinase, the gene inactivated in the Peutz-Jeghers familial cancer syndrome, is the dominant regulator of AMPK activation in several mammalian cell types. We show that LKB1 directly phosphorylates Thr-172 of AMPKalpha in vitro and activates its …

Immune Responses Of Different Mouse Strains After Challenge With Equivalent Lethal Doses Of Toxoplasma Gondii, Y. H. Lee, L. H. Kasper

Dartmouth Scholarship

Most immunological studies that utilize different strains of inbred mice following T. gondii infection fail to compensate for differences in host susceptibility to the size of the parasite innoculum. To address this concern, susceptible C57BL/6 and resistant CBA/J mice were orally infected with either an equivalent 50 % lethal dose (LD₅₀) of brain cysts of the 76K strain of T. gondii (15 cysts in C57BL/6, 400 cysts in CBA/J) or the same dose of parasites in each mouse strain. C57BL/6 mice receiving 400 cysts (LD₅₀ of CBA/J mice) died post infection, whereas CBA/J mice that received 15 …

Probucol Prevents Early Coronary Heart Disease And Death In The High-Density Lipoprotein Receptor Sr-Bi/Apolipoprotein E Double Knockout Mouse, Anne Braun, Songwen Zhang, Helena E. Miettinen, Shamsah Ebrahim, Teresa M. Holm, Eliza Vasile, Mark J. Post

Dartmouth Scholarship

Mice with homozygous null mutations in the high-density lipoprotein receptor SR-BI (scavenger receptor class B, type I) and apolipoprotein E genes fed a low-fat diet exhibit a constellation of pathologies shared with human atherosclerotic coronary heart disease (CHD): hypercholesterolemia, occlusive coronary atherosclerosis, myocardial infarctions, cardiac dysfunction (heart enlargement, reduced systolic function and ejection fraction, and ECG abnormalities), and premature death (mean age 6 weeks). They also exhibit a block in RBC maturation and abnormally high plasma unesterified-to-total cholesterol ratio (0.8) with associated abnormal lipoprotein morphology (lamellar/vesicular and stacked discoidal particles reminiscent of those in lecithin/cholesterol acyltransferase deficiency and cholestasis). Treatment …

Mechanism Of Toxt-Dependent Transcriptional Activation At The Vibrio Cholerae Tcpa Promoter, Robin R. Hulbert, Ronald K. Taylor

Dartmouth Scholarship

The AraC homolog ToxT coordinately regulates virulence gene expression in Vibrio cholerae. ToxT is required for transcriptional activation of the genes encoding cholera toxin and the toxin coregulated pilus, among others. In this work we focused on the interaction of ToxT with the tcpA promoter and investigated the mechanism of ToxT-dependent transcriptional activation at tcpA. Deletion analysis showed that a region from −95 to +2 was sufficient for ToxT binding and activation, both of which were simultaneously lost when the deletion was extended to −63. A collection of point mutations generated by error-prone PCR revealed two small regions required …

Ube1l Is A Retinoid Target That Triggers Pml/Rarα Degradation And Apoptosis In Acute Promyelocytic Leukemia, Sutisak Kitareewan, Ian Pitha-Rowe, David Sekula, Christopher H. Lowrey, Michael J. Nemeth, Todd R. Golub, Sarah J. Freemantle, Ethan Dmitrovsky

Dartmouth Scholarship

All-trans-retinoic acid (RA) treatment induces remissions in acute promyelocytic leukemia (APL) cases expressing the t(15;17) product, promyelocytic leukemia (PML)/RA receptor α (RARα). Microarray analyses previously revealed induction of UBE1L (ubiquitin-activating enzyme E1-like) after RA treatment of NB4 APL cells. We report here that this occurs within 3 h in RA-sensitive but not RA-resistant APL cells, implicating UBE1L as a direct retinoid target. A 1.3-kb fragment of the UBE1L promoter was capable of mediating transcriptional response to RA in a retinoid receptor-selective manner. PML/RARα, a repressor of RA target genes, abolished this UBE1L promoter activity. A hallmark of …