Medicine and Health Sciences Commons^™

The Role Of Sse1 In The De Novo Formation And Variant Determination Of The [Psi+] Prion, Qing Fan, Kyung-Won Park, Zhiqiang Du, Kevin A Morano, Liming Li

Journal Articles

Yeast prions are a group of non-Mendelian genetic elements transmitted as altered and self-propagating conformations. Extensive studies in the last decade have provided valuable information on the mechanisms responsible for yeast prion propagation. How yeast prions are formed de novo and what cellular factors are required for determining prion "strains" or variants--a single polypeptide capable of existing in multiple conformations to result in distinct heritable phenotypes--continue to defy our understanding. We report here that Sse1, the yeast ortholog of the mammalian heat-shock protein 110 (Hsp110) and a nucleotide exchange factor for Hsp70 proteins, plays an important role in regulating [PSI+] …

The Flagellum Of Pseudomonas Aeruginosa Is Required For Resistance To Clearance By Surfactant Protein A, Shiping Zhang, Francis X. Mccormack, Roger C. Levesque, George A. O'Toole, Gee W. Lau

Dartmouth Scholarship

Surfactant protein A (SP-A) is an important lung innate immune protein that kills microbial pathogens by opsonization and membrane permeabilization. We investigated the basis of SP-A-mediated pulmonary clearance of Pseudomonas aeruginosa using genetically-engineered SP-A mice and a library of signature-tagged P. aeruginosa mutants. A mutant with an insertion into flgE, the gene that encodes flagellar hook protein, was preferentially cleared by the SP-A(+/+) mice, but survived in the SP-A(-/-) mice. Opsonization by SP-A did not play a role in flgE clearance. However, exposure to SP-A directly permeabilized and killed the flgE mutant, but not the wild-type parental strain. P. aeruginosa …

Different Dark Conformations Function In Color-Sensitive Photosignaling By The Sensory Rhodopsin I-Htri Complex, Jun Sasaki, Brian J Phillips, Xinpu Chen, Ned Van Eps, Ah-Lim Tsai, Wayne L Hubbell, John L Spudich

Journal Articles

The haloarchaeal phototaxis receptor sensory rhodopsin I (SRI) in complex with its transducer HtrI delivers an attractant signal from excitation with an orange photon and a repellent signal from a second near-UV photon excitation. Using a proteoliposome system with purified SRI in complex with its transducer HtrI, we identified by site-directed fluorescence labeling a site (Ser(155)) on SRI that is conformationally active in signal relay to HtrI. Using site-directed spin labeling of Ser(155)Cys with a nitroxide side chain, we detected a change in conformation following one-photon excitation such that the spin probe exhibits a splitting of the outer hyperfine extrema …

Importance Of The Ebp (Endocarditis- And Biofilm-Associated Pilus) Locus In The Pathogenesis Of Enterococcus Faecalis Ascending Urinary Tract Infection, Kavindra V Singh, Sreedhar R Nallapareddy, Barbara E Murray

Journal Articles

BACKGROUND: We recently demonstrated that the ubiquitous Enterococcus faecalis ebp (endocarditis- and biofilm-associated pilus) operon is important for biofilm formation and experimental endocarditis. Here, we assess its role in murine urinary tract infection (UTI) by use of wild-type E. faecalis OG1RF and its nonpiliated, ebpA allelic replacement mutant (TX5475).

METHODS: OG1RF and TX5475 were administered transurethrally either at an ~1 : 1 ratio (competition assay) or individually (monoinfection). Kidney pairs and urinary bladders were cultured 48 h after infection. These strains were also tested in a peritonitis model.

RESULTS: No differences were observed in the peritonitis model. In mixed UTIs, …

The Modifier Of Min 2 (Mom2) Locus: Embryonic Lethality Of A Mutation In The Atp5a1 Gene Suggests A Novel Mechanism Of Polyp Suppression., Amy A Baran, Karen A Silverman, Joseph Zeskand, Revati Koratkar, Ashley Palmer, Kristen Mccullen, Walter J Curran, Tina Bocker Edmonston, Linda D Siracusa, Arthur M Buchberg

Kimmel Cancer Center Faculty Papers

Inactivation of the APC gene is considered the initiating event in human colorectal cancer. Modifier genes that influence the penetrance of mutations in tumor-suppressor genes hold great potential for preventing the development of cancer. The mechanism by which modifier genes alter adenoma incidence can be readily studied in mice that inherit mutations in the Apc gene. We identified a new modifier locus of ApcMin-induced intestinal tumorigenesis called Modifier of Min 2 (Mom2). The polyp-resistant Mom2R phenotype resulted from a spontaneous mutation and linkage analysis localized Mom2 to distal chromosome 18. To obtain recombinant chromosomes for use in refining the Mom2 …

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 …

Colon Carcinoma Cells Harboring Pik3ca Mutations Display Resistance To Growth Factor Deprivation Induced Apoptosis., J. Wang, Karen Kuropatwinski, Jennie Hauser, Michael R. Rossi, Yunfei Zhou, Alexis Conway, Julie L.C. Kan, Neil W. Gibson, James K.V. Willson, John K. Cowell, Michael G. Brattain

Journal Articles: Eppley Institute

PIK3CA, encoding the p110alpha catalytic subunit of phosphatidylinositol 3-kinase (PI3K), is mutated in a variety of human cancers. We screened the colon cancer cell lines previously established in our laboratory for PIK3CA mutations and found that four of them harbored gain of function mutations. We have now compared a panel of mutant and wild-type cell lines for cell proliferation and survival in response to stress. There was little difference in PI3K activity between mutant PIK3CA-bearing cells (mutant cells) and wild-type PIK3CA-bearing cells (wild-type cells) under optimal growth conditions. However, the mutant cells showed constitutive PI3K activity during growth factor deprivation …

Aldosterone-Induced Sgk1 Relieves Dot1a-Af9-Mediated Transcriptional Repression Of Epithelial Na+ Channel Alpha, Wenzheng Zhang, Xuefeng Xia, Mary Rose Reisenauer, Timo Rieg, Florian Lang, Dietmar Kuhl, Volker Vallon, Bruce C Kone

Journal Articles

Aldosterone plays a major role in the regulation of salt balance and the pathophysiology of cardiovascular and renal diseases. Many aldosterone-regulated genes--including that encoding the epithelial Na+ channel (ENaC), a key arbiter of Na+ transport in the kidney and other epithelia--have been identified, but the mechanisms by which the hormone modifies chromatin structure and thus transcription remain unknown. We previously described the basal repression of ENaCalpha by a complex containing the histone H3 Lys79 methyltransferase disruptor of telomeric silencing alternative splice variant a (Dot1a) and the putative transcription factor ALL1-fused gene from chromosome 9 (Af9) as well as the release …

Severe Aortic And Arterial Aneurysms Associated With A Tgfbr2 Mutation, Scott A Lemaire, Hariyadarshi Pannu, Van Tran-Fadulu, Stacey A Carter, Joseph S Coselli, Dianna M Milewicz

Journal Articles

BACKGROUND: A 24-year-old man presented with previously diagnosed Marfan's syndrome. Since the age of 9 years, he had undergone eight cardiovascular procedures to treat rapidly progressive aneurysms, dissection and tortuous vascular disease involving the aortic root and arch, the thoracoabdominal aorta, and brachiocephalic, vertebral, internal thoracic and superior mesenteric arteries. Throughout this extensive series of cardiovascular surgical repairs, he recovered without stroke, paraplegia or renal impairment.

INVESTIGATIONS: CT scans, arteriogram, genetic mutation screening of transforming growth factor beta receptors 1 and 2.

DIAGNOSIS: Diffuse and rapidly progressing vascular disease in a patient who met the diagnostic criteria for Marfan's syndrome, …

Oncolog, Volume 52, Number 12, December 2007, Sunni Hosemann, Diane Witter, Huong Le-Petross Md

OncoLog MD Anderson's Report to Physicians (All issues)

• Worth More than a Thousand Words\
• A Step Forward for Stents
• House Call: Getting the Most From Your Doctor Visit
• DiaLog: Is MRI Better for Breast Screening?, by Huong Le-Petross, MD