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The Tim54p–Tim22p Complex Mediates Insertion Of Proteins Into The Mitochondrial Inner Membrane, Oliver Kerscher, Jason Holder, Maithreyan Srinivasan, Roxanne S. Leung, Robert E. Jensen

Arts & Sciences Articles

We have identified a new protein, Tim54p, located in the yeast mitochondrial inner membrane. Tim54p is an essential import component, required for the insertion of at least two polytopic proteins into the inner membrane, but not for the translocation of precursors into the matrix. Several observations suggest that Tim54p and Tim22p are part of a protein complex in the inner membrane distinct from the previously characterized Tim23p-Tim17p complex. First, multiple copies of the TIM22 gene, but not TIM23 or TIM17, suppress the growth defect of a tim54-1 temperature-sensitive mutant. Second, Tim22p can be coprecipitated with Tim54p from detergent-solubilized mitochondria, …

Alterations In Calcium Homeostasis And The Insulin-Like Growth Factor Signaling Pathway Induced By Carcinogenic Polycyclic And Halogenated Aromatic Hydrocarbons In Human Mammary Epithelial Cells, Stacey L. Tannheimer

Pharmaceutical Sciences ETDs

Breast cancer is a major health concern for women, with only a small percent of the risk factors currently identified. It has been estimated that environmental factors may contribute to up to 80% of breast cancer cases. Many environmental carcinogens, such as polycyclic and halogenated aromatic hydrocarbons (PAHs and HAHs), are proven mammary carcinogens in animal models. Therefore, these studies were conducted to elucidate potential roles of PAHs and HAHs in alterations in known signaling pathways in human mammary epithelial cells (HMEC). Carcinogenic PAHs have previously been shown to produce sustained alterations in the calcium (Ca2') homeostasis of lymphocytes Therefore, …

Coupled Er To Golgi Transport Reconstituted With Purified Cytosolic Proteins, Charles Barlowe

Dartmouth Scholarship

A cell-free vesicle fusion assay that reproduces a subreaction in transport of pro-alpha-factor from the ER to the Golgi complex has been used to fractionate yeast cytosol. Purified Sec18p, Uso1p, and LMA1 in the presence of ATP and GTP satisfies the requirement for cytosol in fusion of ER-derived vesicles with Golgi membranes. Although these purified factors are sufficient for vesicle docking and fusion, overall ER to Golgi transport in yeast semi-intact cells depends on COPII proteins (components of a membrane coat that drive vesicle budding from the ER). Thus, membrane fusion is coupled to vesicle formation in ER to Golgi …

Inhibition Of Axonal Growth By Brefeldin A In Hippocampal Neurons In Culture, Mark Jareb, Gary Banker

Biology Faculty Publications

The outgrowth of neuronal processes involves a great increase in the surface area of the cell. The supply of membrane material necessarily must be coordinated with the demands for neurite growth. The selective growth of only one or two neurites at any given time during the development of polarity raises the possibility that the production of materials by the soma is limiting for growth (Dotti and Banker, 1987; Dotti et al., 1988; Goslin and Banker, 1990). To examine the role of the availability of membrane components during the development of polarity and axonal elongation, we treated neurons with brefeldin A, …

Altered Trafficking Of Mutant Connexin32, Suzanne M. Deschênes, Jessica L. Walcott, Tamara L. Wexler, Steven S. Scherer, Kenneth H. Fischbeck

Biology Faculty Publications

We examined the cellular localization of nine different connexin32 (Cx32) mutants associated with X-linked Charcot–Marie–Tooth disease (CMTX) in communication-incompetent mammalian cells. Cx32 mRNA was made, but little or no protein was detected in one class of mutants. In another class of mutants, Cx32 protein was detectable in the cytoplasm and at the cell surface, where it appeared as plaques and punctate staining. Cx32 immunoreactivity in a third class of mutants was restricted to the cytoplasm, where it often colocalized with the Golgi apparatus. Our studies suggest that CMTX mutations have a predominant effect on the trafficking of Cx32 protein, resulting …

Effects Of Oxidized Low Density Lipoprotein On Nitric Oxide Production In Macrophages, Annong Huang

Electronic Theses and Dissertations

The effects of oxidatively modified low density lipoprotein (oxLDL) on atherogenesis may be partly mediated by alterations in nitric oxide (NO) production by macrophages. A major goal of this study was to identify the lipid components in oxLDL modulating NO production. The effect of a water soluble antioxidants (N-acetylcysteine) and lipid soluble antioxidant (alpha-tocopherol) on NO production in macrophages was also determined. A second goal was to determine if the effects of oxLDL occurred at the transcriptional level. Human LDL was oxidized using an azo-initiator 2,2$\sp\prime$-azobis (2-amidinopropane) HCI (ABAP). OxLDL markedly decreased the production of NO in LPS stimulated RAW264.7 …

Comparison Of Beta-Adrenoceptor Coupled Camp Production In Cultured Human Mononuclear Leukocytes And Myometrial Cells, Yu-Li Liu

Electronic Theses and Dissertations

$\beta\sb2$-Adrenoceptor ($\beta\sb2$-AR) agonists, such as terbutaline, are used as tocolytic agents in the treatment of preterm labor. $\beta$-Adrenoceptor stimulation relaxes myometrium through specific receptors coupled through Gs to adenylyl cyclase (AC) that catalyzes the conversion of ATP to cAMP. The purpose of this study was to compare $\beta$-adrenoceptors and cAMP production in cultured human leukocytes and myometrial cells, and to determine the importance of $\beta$-adrenoceptors and cAMP production in isoproterenol-induced myometrial relaxation. $\sp{125}$I-iodopindolol was used to assess $\beta$-adrenoceptor affinity and number cAMP levels were analyzed before and after stimulation by isoproterenol, AlF$\sb4\sp-$, forskolin, and PGE$\sb1$. Isometric recording was used to …

Recovery Of Rna Polymerase Ii Synthesis Following Dna Damage In Mutants Of Saccharomyces Cerevisiae Defective In Nucleotide Excision Repair, Michael S. Reagan, Errol C. Friedberg

Biology Faculty Publications

We have measured the kinetics of the recovery of mRNA synthesis in the inducible GAL10 and RNR3 genes after exposure of yeast cells to ultraviolet (UV) radiation. Such recovery is abolished in mutant strains defective in nucleotide excision repair (NER) of DNA, including a rad23 mutant. Mutants defective in the RAD7 or RAD16 genes, which are required for the repair of the non-transcribed strand but not the transcribed strand of transcriptionally active genes, show slightly faster recovery of RNA synthesis than wild-type strains. A strain deleted of the RAD26 gene, which is known to be required for strand-specific NER in …

Endogenous Alkylglycerol Functions As A Mediator Of Protein Kinase C Activity And Cell Proliferation, Fritz G. Buchanan

Electronic Theses and Dissertations

To explore the possibility that 1-O-alkyl-sn-glycerol (alkylglycerol) may serve a regulatory role in the control of cell proliferation or PKC activity, we examined the ability of alkylglycerol to influence PKC activity and subcellular distribution as well as the ability of alkylglycerol to effect cell proliferation. MDCK cells grown to confluence show a loss of PKC activity associated with the membrane, as reported in fibroblasts. Preconfluent cultures of MDCK cells have a high level of PKC activity associated with the membrane. However, treatment of preconfluent cultures with alkylglycerol causes a reduction of PKC activity. A similar inhibition was observed with alkylglycerol …

Endosome To Golgi Retrieval Of The Vacuolar Protein Sorting Receptor, Vps10p, Requires The Function Of The Vps29, Vps30, And Vps35 Gene Products, Matthew N. J. Seaman, Eric G. Marcusson, Joan Lin-Cereghino, Scott D. Emr

College of the Pacific Faculty Articles

Mutations in the S. cerevisiae VPS29 and VPS30 genes lead to a selective protein sorting defect in which the vacuolar protein carboxypeptidase Y (CPY) is missorted and secreted from the cell, while other soluble vacuolar hydrolases like proteinase A (PrA) are delivered to the vacuole. This phenotype is similar to that seen in cells with mutations in the previously characterized VPS10 and VPS35 genes. Vps10p is a late Golgi transmembrane protein that acts as the sorting receptor for soluble vacuolar hydrolases like CPY and PrA, while Vps35p is a peripheral membrane protein which cofractionates with membranes enriched in Vps10p. The …

Alterations In Human B Cell Calcium Homeostasis By Polycyclic Aromatic Hydrocarbons: Possible Associations With Cytochrome P450 Metabolism And Increased Tyrosine Phosphorylation, Barbara J. Mounho

Pharmaceutical Sciences ETDs

Polycyclic aromatic hydrocarbons (PAHs), are known immunotoxicants in animals, and are suspect toxins to the human immune system. The mechanism(s), however, by which PAHs exert immunosuppression have not been fully elucidated. Previous studies conducted in our laboratory have shown that PAHs, such as 7,12-dimethylbenz(a)- anthracene (DMB A) and benzo(a)pyrene (BaP) may exert their immunotoxic effects by altering intracellular calcium (Ca2+) homeostasis in lymphocytes. Intracellular Ca2+ is an important second messenger in the immune response, and the mobilization of Ca2+ is critical in the transduction of intracellular signals from the plasma membrane to the nucleus. The overall objective of this project …

Cγ- And Cα-Subunits Provide The Specificity For Camp/Pka Function, Wei Qing Zhang

Theses and Dissertations in Biomedical Sciences

The Cα and Cγ of the cAMP-dependent protein kinase (PKA) are two highly homologous (83% amino acid identity), yet functionally distinct isozymes in vitro for substrate and pseudosubstrate specificity, and in intact cells for cell phenotypes (Beebe, 1992).

To determine the molecular mechanisms underlying the distinct functions in cell phenotypes, in vitro experiments were designed to make a detailed comparison of Cγ and Cα for substrate and pseudosubstrate specificity. To this end, Cγ and Cα were expressed m mammalian cells, bacteria and Sf9 insect cells using baculovirus. Abundant expression of active enzyme was cell system specific. Cγ and Cα expressed …

Analysis Of Gene Expression During Embryonic Development In Mulberry Silkworm Bombyx Mori, Amit Singh, K. P. Gopinathan

Biology Faculty Publications

We have developed a method for dechorionation and devitellinization of the silkworm eggs without damage, to facilitate the analysis of gene expression during embryonic development of Bombyx mori. Making use of antibodies available from heterologous systems, the spatio-temporal expression patterns of peroxidase and proliferating cell nuclear antigen have been directly visualized in whole mount embryos at various stages of development without the need for generating transformed ·lines carrying specific reporter constructs. The B. mori system, previously unamenable for such studies, could thus serve as an attractive model for molecular analysis of insect development.

The attention lavished on Drosophila melanogaster as …

A Heterodimer Of Thioredoxin And Ib2 Cooperates With Sec18p (Nsf) To Promote Yeast Vacuole Inheritance, Zuoyu Xu, Andreas Mayer, Eric Muller, William Wickner

Dartmouth Scholarship

Early in S phase, the vacuole (lysosome) of Saccharomyces cerevisiae projects a stream of vesicles and membranous tubules into the bud where they fuse and establish the daughter vacuole. This inheritance reaction can be studied in vitro with isolated vacuoles. Rapid and efficient homotypic fusion between saltwashed vacuoles requires the addition of only two purified soluble proteins, Sec18p (NSF) and LMA1, a novel heterodimer with a thioredoxin subunit. We now report the identity of the second subunit of LMA1 as IB2, a previously identified cytosolic inhibitor of vacuolar proteinase B. Both subunits are needed for efficient vacuole inheritance in vivo …

In Vivo Incorporation Of Tritium To Measure Lipogenesis In Red Skeletal Muscle: Significance Of A Nonlipogenic Diet In La/N-Fa(K)("Corpulent") And Zucker Fa Rat Strains, Karin Traci Mann

Theses, Dissertations and Capstones

Skeletal muscle lipogenesis in rodents may equal that of liver but its importance in the obese animals is not known. We evaluated the rate of fatty acid and triglyceride synthesis and storage content in red skeletal muscles, liver, inguinal fat, and retroperitoneal fat of the LA/N-fa^k (“corpulent”) and Zucker fa obese rat strains. Obese-lean pairs of both rat strains, weaned at 32 days, fed a nonlipogenic diet (54% starch for 21 days) were either dosed with 2 µCi 3H-H² O per gram of body weight and tested after 60 minutes for whole body 3H-incorporation into fatty acids and …

The Regulation Of Glucose Transport In Cultured Vascular Smooth Muscle Cells By Angiotensin Ii And Glucose, Leslie Ann Quinn

Theses, Dissertations and Capstones

Glucose transport was assessed in vascular smooth muscle (VSM) cells by measuring the uptake of a radiolabeled non-metabolizable glucose analog, [3H]-2-deoxglucose. VSM cells, isolated from rat aortae by enzymatic digestion, were maintained in culture in Dulbecco's Modified Eagle Medium supplemented with 10% newborn calf serum at 37°C with 5% CO2 and air. Angiotensin II (AU) increased glucose transport by 84%. Significant stimulation occurred by two hours of exposure with the maximum effect being observed between six and eight hours. All effects were concentration dependent with a threshold response being detected at 0.1 nM. All-stimulated transport was blocked by an AU …

The Drosophila Melanogaster Rad54 Homolog, Dmrad54, Is Involved In The Repair Of Radiation Damage And Recombination, Rolf Kooistra, José B. M. Zonneveld, Anja De Jong, Jan C. J. Eeken, Chris J. Osgood, Jean-Marie Buerstedde, Paul H. M. Lohman, Albert Pastink

Biological Sciences Faculty Publications

The RAD54 gene of Saccharomyces cerevisiae plays a crucial role in recombinational repair of double-strand breaks in DNA. Here the isolation and functional characterization of the RAD54 homolog of the fruit fly Drosophila melanogaster, DmRAD54, are described. The putative Dmrad54 protein displays 46 to 57% identity to its homologs from yeast and mammals. DmRAD54 RNA was detected at all stages of fly development, but an increased level was observed in early embryos and ovarian tissue. To determine the function of DmRAD54, a null mutant was isolated by random mutagenesis. DmRAD54-deficient flies develop normally, but the females …

Assignment Of Fragile Site 8e (Fra8e) To Human Chromosome Band 8q24.11 Adjacent To The Hereditary Multiple Exostoses 1 Gene And Two Overlapping Langer-Giedion Syndrome Deletion Endpoints, April L. Hill, Y. Harada, E. Takahashi, J. Hou, M. J. Wagner, D. E. Wells

Biology Faculty Publications

The distamycin A inducible fragile site, FRA8E, Fra(8) (q24.11) has been previously mapped to 8q24.11, proximal to the MYC gene, by fluorescent in situ hybridization (Takahasi et al., 1991). This fragile site has been shown to be present in about 1 out of every 140 healthy Japanese individuals (Takahasi et al., 1988). To more precisely map FRA8E, we have used cosmids isolated from the Langer-Giedion chromosomal region (LGCR) for FISH analysis. Langer-Giedion syndrome (LGS) is a contiguous gene syndrome characterized by chromosome deletions in Sq24.11 (Ludecke et al., 1991). One of the genes known to be involved in the etiology …

Abnormalities In Post-Translational Processing Of Platelet Rap 1b In Niddm: A Possible Cause Of Platelet Hyperactivity And Cardiovascular Disease In Diabetes, Elizabeth Ann Hall

Theses and Dissertations in Biomedical Sciences

Post-translational processing is critical for the appropriate subcellular localization and function of platelet G-proteins. The majority of the platelet responses to agonists are mediated through specific receptor/G-protein complexes. Therefore, G-protein activity is central to "normal" platelet activity (i.e. aggregation). We have shown that Simvastatin, the in vivo inhibitor of HMG CoA Reductase and therefore isoprenoid synthesis, inhibits the post-translational processing of specific platelet G-proteins and alters platelet responses to agonists. These results show the importance of post-translational processing of G-proteins to platelet activity. Altered post-translational processing of specific G-proteins may explain platelet hyperactivity and the increased incidence of cardiovascular disease …