Medicine and Health Sciences | Open Access Articles

H-Ns Binding And Repression Of The Ctx Promoter In Vibrio Cholerae, Emily A. Stonehouse, Robin R. Hulbert, Melinda B. Nye, Karen Skorupski, Ronald K. Taylor

Dartmouth Scholarship

Expression of the ctx and tcp genes, which encode cholera toxin and the toxin coregulated pilus, the Vibrio cholerae O1 virulence determinants having the largest contribution to cholera disease, is repressed by the nucleoid-associated protein H-NS and activated by the AraC-like transcriptional regulator ToxT. To elucidate the molecular mechanism by which H-NS controls transcription of the ctxAB operon, H-NS repression and binding were characterized by using a promoter truncation series, gel mobility shift assays, and DNase I footprinting. Promoter regions found to be important for H-NS repression correlated with in vitro binding. Four main H-NS binding regions are present at …

Go to article

Carhsp1 Is Required For Effective Tumor Necrosis Factor Alpha Mrna Stabilization And Localizes To Processing Bodies And Exosomes, Jason R. Pfeiffer, Bethany L. Mcavoy, Ryan E. Fecteau, Kristen M. Deleault, Seth A. Brooks

Dartmouth Scholarship

Tumor necrosis factor alpha (TNF-α) is a critical mediator of inflammation, and its production is tightly regulated, with control points operating at nearly every step of its biosynthesis. We sought to identify uncharacterized TNF-α 3' untranslated region (3'UTR)-interacting proteins utilizing a novel screen, termed the RNA capture assay. We identified CARHSP1, a cold-shock domain-containing protein. Knockdown of CARHSP1 inhibits TNF-α protein production in lipopolysaccharide (LPS)-stimulated cells and reduces the level of TNF-α mRNA in both resting and LPS-stimulated cells. mRNA stability assays demonstrate that CARHSP1 knockdown decreases TNF-α mRNA stability from a half-life (t(1/2)) of 49 min to a t(1/2) …

Go to article

Development Of Pyrf-Based Genetic System For Targeted Gene Deletion In Clostridium Thermocellum And Creation Of A Pta Mutant, Shital A. Tripathi, Daniel G. Olson, D. Aaron Argyros, Bethany B. Miller, Trisha F. Barrett, Daniel M. Murphy, Jesse D. Mccool, Anne K. Warner, Vineet B. Rajgarhia, Lee R. Lynd, David A. Hogsett, Nicky C. Caiazza

Dartmouth Scholarship

We report development of a genetic system for making targeted gene knockouts in Clostridium thermocellum, a thermophilic anaerobic bacterium that rapidly solubilizes cellulose. A toxic uracil analog, 5-fluoroorotic acid (5-FOA), was used to select for deletion of the pyrF gene. The ΔpyrF strain is a uracil auxotroph that could be restored to a prototroph via ectopic expression of pyrF from a plasmid, providing a positive genetic selection. Furthermore, 5-FOA was used to select against plasmid-expressed pyrF, creating a negative selection for plasmid loss. This technology was used to delete a gene involved in organic acid production, namely pta, which encodes …

Go to article

Breast Cancer Dna Methylation Profiles Are Associated With Tumor Size And Alcohol And Folate Intake, Brock C. Christensen, Karl T. Kelsey, Shichun Zheng, E. Andres Houseman, Carmen J. Marsit, Margaret R. Wrensch, Joseph L. Wiemels, Heather H. Nelson, Margaret R. Karagas

Dartmouth Scholarship

Although tumor size and lymph node involvement are the current cornerstones of breast cancer prognosis, they have not been extensively explored in relation to tumor methylation attributes in conjunction with other tumor and patient dietary and hormonal characteristics. Using primary breast tumors from 162 (AJCC stage I-IV) women from the Kaiser Division of Research Pathways Study and the Illumina GoldenGate methylation bead-array platform, we measured 1,413 autosomal CpG loci associated with 773 cancer-related genes and validated select CpG loci with Sequenom EpiTYPER. Tumor grade, size, estrogen and progesterone receptor status, and triple negative status were significantly (Q-values <0.05) associated with altered methylation of 209, 74, 183, 69, and 130 loci, respectively. Unsupervised clustering, using a recursively partitioned mixture model (RPMM), of all autosomal CpG loci revealed eight distinct methylation classes. Methylation class membership was significantly associated with patient race (P<0.02) and tumor size (P<0.001) in univariate tests. Using multinomial logistic regression to adjust for potential confounders, patient age and tumor size, as well as known disease risk factors of alcohol intake and total dietary folate, were all significantly (P<0.0001) associated with methylation class membership. Breast cancer prognostic characteristics and risk-related exposures appear to be associated with gene-specific tumor methylation, as well as overall methylation patterns.

Go to article

Role Of Flgt In Anchoring The Flagellum Of Vibrio Cholerae, Raquel M. Martinez, Brooke A. Jude, Thomas J. Kirn, Karen Skorupski, Ronald K. Taylor

Dartmouth Scholarship

Flagellar motility has long been regarded as an important virulence factor. In Vibrio cholerae, the single polar flagellum is essential for motility as well as for proper attachment and colonization. In this study, we demonstrate that the novel flagellar protein FlgT is involved in anchoring the flagellum to the V. cholerae cell. A screen for novel colonization factors by use of TnphoA mutagenesis identified flgT. An in-frame deletion of flgT established that FlgT is required for attachment, colonization, and motility. Transmission electron microscopy revealed that while the flgT mutant is capable of assembling a phenotypically normal flagellum, …

Go to article

Microrna-31 Functions As An Oncogenic Microrna In Mouse And Human Lung Cancer Cells By Repressing Specific Tumor Suppressors, Xi Liu, Lorenzo F. Sempere, Haoxu Ouyang, Vincent A. Memoli, Angeline S. Andrew, Yue Luo, Eugene Demidenko, Murray Korc, Wei Shi, Meir Preis, Konstantin H. Dragnev, Hua Li, James Direnzo, Mads Bak, Sarah J. Freemantle, Sakari Kauppinen, Ethan Dmitrovsky

Dartmouth Scholarship

MicroRNAs (miRNAs) regulate gene expression. It has been suggested that obtaining miRNA expression profiles can improve classification, diagnostic, and prognostic information in oncology. Here, we sought to comprehensively identify the miRNAs that are overexpressed in lung cancer by conducting miRNA microarray expression profiling on normal lung versus adjacent lung cancers from transgenic mice. We found that miR-136, miR-376a, and miR-31 were each prominently overexpressed in murine lung cancers. Real-time RT-PCR and in situ hybridization (ISH) assays confirmed these miRNA expression profiles in paired normal-malignant lung tissues from mice and humans. Engineered knockdown of miR-31, but not other highlighted miRNAs, substantially …

Go to article

Acat1 Gene Ablation Increases 24(S)-Hydroxycholesterol Content In The Brain And Ameliorates Amyloid Pathology In Mice With Ad, Elena Y. Bryleva, Maximillian A. Rogers, Catherine C. Y. Chang, Floyd Buen

Dartmouth Scholarship

Cholesterol metabolism has been implicated in the pathogenesis of several neurodegenerative diseases, including the abnormal accumulation of amyloid-beta, one of the pathological hallmarks of Alzheimer disease (AD). Acyl-CoA:cholesterol acyltransferases (ACAT1 and ACAT2) are two enzymes that convert free cholesterol to cholesteryl esters. ACAT inhibitors have recently emerged as promising drug candidates for AD therapy. However, how ACAT inhibitors act in the brain has so far remained unclear. Here we show that ACAT1 is the major functional isoenzyme in the mouse brain. ACAT1 gene ablation (A1-) in triple transgenic (i.e., 3XTg-AD) mice leads to more than 60% reduction in full-length human …

Go to article

Structure Of Vibrio Cholerae Toxt Reveals A Mechanism For Fatty Acid Regulation Of Virulence Genes, Michael J. Lowden, Karen Skorupski, Maria Pellegrini, Michael G. Chiorazzo, Ronald K. Taylor, F. Jon Kull

Dartmouth Scholarship

Cholera is an acute intestinal infection caused by the bacterium Vibrio cholerae. In order for V. cholerae to cause disease, it must produce two virulence factors, the toxin-coregulated pilus (TCP) and cholera toxin (CT), whose expression is controlled by a transcriptional cascade culminating with the expression of the AraC-family regulator, ToxT. We have solved the 1.9 A resolution crystal structure of ToxT, which reveals folds in the N- and C-terminal domains that share a number of features in common with AraC, MarA, and Rob as well as the unexpected presence of a buried 16-carbon fatty acid, cis-palmitoleate. The finding that …

Go to article

Progressive Changes In Microglia And Macrophages In Spinal Cord And Peripheral Nerve In The Transgenic Rat Model Of Amyotrophic Lateral Sclerosis, David J. Graber, William F. Hickey, Brent T. Harris

Dartmouth Scholarship

The role of neuroinflammation in motor neuron death of amyotrophic lateral sclerosis (ALS) is unclear. The human mutant superoxide dismutase-1 (hmSOD1)-expressing murine transgenic model of ALS has provided some insight into changes in microglia activity during disease progression. The purpose of this study was to gain further knowledge by characterizing the immunological changes during disease progression in the spinal cord and peripheral nerve using the more recently developed hmSOD1 rat transgenic model of ALS. Using immunohistochemistry, the extent and intensity of tissue CD11b expression in spinal cord, lumbar nerve roots, and sciatic nerve were evaluated in hmSOD1 rats that were …

Go to article

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 …

Go to article

Medicine and Health Sciences Commons^™

Full-Text Articles in Medicine and Health Sciences

H-Ns Binding And Repression Of The Ctx Promoter In Vibrio Cholerae, Emily A. Stonehouse, Robin R. Hulbert, Melinda B. Nye, Karen Skorupski, Ronald K. Taylor

Dartmouth Scholarship

Carhsp1 Is Required For Effective Tumor Necrosis Factor Alpha Mrna Stabilization And Localizes To Processing Bodies And Exosomes, Jason R. Pfeiffer, Bethany L. Mcavoy, Ryan E. Fecteau, Kristen M. Deleault, Seth A. Brooks

Dartmouth Scholarship

Dartmouth Scholarship

Breast Cancer Dna Methylation Profiles Are Associated With Tumor Size And Alcohol And Folate Intake, Brock C. Christensen, Karl T. Kelsey, Shichun Zheng, E. Andres Houseman, Carmen J. Marsit, Margaret R. Wrensch, Joseph L. Wiemels, Heather H. Nelson, Margaret R. Karagas

Dartmouth Scholarship

Role Of Flgt In Anchoring The Flagellum Of Vibrio Cholerae, Raquel M. Martinez, Brooke A. Jude, Thomas J. Kirn, Karen Skorupski, Ronald K. Taylor

Dartmouth Scholarship

Dartmouth Scholarship

Acat1 Gene Ablation Increases 24(S)-Hydroxycholesterol Content In The Brain And Ameliorates Amyloid Pathology In Mice With Ad, Elena Y. Bryleva, Maximillian A. Rogers, Catherine C. Y. Chang, Floyd Buen

Dartmouth Scholarship

Structure Of Vibrio Cholerae Toxt Reveals A Mechanism For Fatty Acid Regulation Of Virulence Genes, Michael J. Lowden, Karen Skorupski, Maria Pellegrini, Michael G. Chiorazzo, Ronald K. Taylor, F. Jon Kull

Dartmouth Scholarship

Progressive Changes In Microglia And Macrophages In Spinal Cord And Peripheral Nerve In The Transgenic Rat Model Of Amyotrophic Lateral Sclerosis, David J. Graber, William F. Hickey, Brent T. Harris

Dartmouth Scholarship

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

Dartmouth Scholarship