Le macrophage joue un rôle clé dans l'athérogenèse, intervenant notamment, dans la captation de cholestérol à l'origine de la formation des stries lipidiques. Sa capacité à éliminer le cholestérol en excès est donc critique pour l'évolution de la pathologie. Il intervient aussi dans la captation des cellules apoptotiques présentes au sein de la lésion, processus déterminant en termes d'inflammation et de stabilité de la plaque. Mes travaux ont consisté à évaluer le rôle du transporteur ATP-Binding-Cassette G1 (ABCG1), dans ces mécanismes clés de l'athérogenèse. Ainsi, nous avons donc montré qu'ABCG1 est à la fois impliqué dans les processus d'efflux au sein des cellules spumeuses chargées en cholestérol libre mais aussi qu'il participe au mécanisme de phagocytose des corps apoptotiques. Ainsi, grâce à ces travaux ABCG1 pourrait être envisagé comme une nouvelle cible thérapeutique de l'athérosclérose.

SUR2A is a member of the ABC transporter superfamily. SUR2A mediated regulation of KATP channels is essential as mutations in the nucleotide binding domains (NBDs) of SUR2A are associated with cardiovascular disorders. Studies of eukaryotic NBDs, such as SUR2A, are hindered by low solubility of the isolated domain. We hypothesized that the solubility of heterologously expressed SUR2A NBDs depends on the definition of the domain boundaries. Boundaries were initially predicted using a combination of a structure-based sequence alignment and homology modeling, and subsequently verified by testing the solubility of five SUR2A NBD1 constructs with different N- or C-terminal boundaries. The boundaries of SUR2A NBD1 essential for solubility were identified. CD and NMR data indicate that SUR2A NBD1 is folded. Our method may be applied as a general method for developing suitable constructs of other NBDs of ABC proteins such as SUR isoforms, SUR2B and SUR2C, and the vacuolar transporter, Ycf1p.

ATP-sensitive potassium (KATP) channels have crucial roles in several biological processes. KATP channels possess four regulatory sulfonylurea receptors. The SUR proteins are members of the ubiquitous ATP-binding cassette (ABC) superfamily. However, unlike most ABC proteins, SURs do not transport substrates but function strictly as regulators of KATP channel activity. Currently, studies into the molecular basis by which various mutations in SUR2A cause disease are highly limited. This is primarily a consequence of poor solubility of isolated SUR2A NBDs, as is typical for many eukaryotic NBDs. By employing structure-based sequence alignments and biophysical studies, we determined domain boundaries for SUR2A NBD1 that enabled, for the first time, NMR studies of NBD1. Our biophysical studies demonstrate that the isolated SUR2A NBD1 is folded and exhibits differential dynamics upon ATP binding activity. Additional studies are now possible to examine the effects of disease-causing mutations on structure, dynamics, and interactions of NBD1.

Bakgrund: Dagens företag präglas i hög utsträckning av ett resultatenhetstänkande. När handel sker mellan dessa enheter uppstår vissa problem med prissättningen för dessa transfereringar. Dessa priser brukar kallas internpriser och har behandlats i litteraturen sedan 1920-talet. Vi har därför funnit detta intressant att se hur internprisproblematiken ser ut i litteraturen jämfört med den verklighet som råder i dag. Syfte: Att studera internprislitteraturens praktiska tillämpbarhet och på så sätt försöka utveckla och förnya den. Genomförande: För att uppnå vårt syfte har vi med utgångspunkt i litteraturen försökt ta fram ett internpris i ett fallföretag, Gränges, för att se om detta var möjligt så som litteraturen ser ut idag. Uppgiften har krävt dels en litteraturgenomgång och dels en noggrann studie av fallföretaget. Företagsstudien har gjorts dels genom intervjuer med personer i Gränges som arbetar med internprissättningen och dels genom egna efterforskningar i datasystem och bland personal på företaget, Internet och årsredovisningar. Resultat: Vi har funnit litteraturen mycket användbar under vårt arbete. Dock kan vissa uppdateringar behövas och det gäller att man anpassar och kombinerar olika teorier utefter hur situationen man befinner sig i ser ut. Det är sällan verkligheten överensstämmer till fullo med litteraturens beskrivning av den.

SUR2A is a member of the ABC transporter superfamily. SUR2A mediated regulation of KATP channels is essential as mutations in the nucleotide binding domains (NBDs) of SUR2A are associated with cardiovascular disorders. Studies of eukaryotic NBDs, such as SUR2A, are hindered by low solubility of the isolated domain. We hypothesized that the solubility of heterologously expressed SUR2A NBDs depends on the definition of the domain boundaries. Boundaries were initially predicted using a combination of a structure-based sequence alignment and homology modeling, and subsequently verified by testing the solubility of five SUR2A NBD1 constructs with different N- or C-terminal boundaries. The boundaries of SUR2A NBD1 essential for solubility were identified. CD and NMR data indicate that SUR2A NBD1 is folded. Our method may be applied as a general method for developing suitable constructs of other NBDs of ABC proteins such as SUR isoforms, SUR2B and SUR2C, and the vacuolar transporter, Ycf1p.

ATP-sensitive potassium (KATP) channels have crucial roles in several biological processes. KATP channels possess four regulatory sulfonylurea receptors. The SUR proteins are members of the ubiquitous ATP-binding cassette (ABC) superfamily. However, unlike most ABC proteins, SURs do not transport substrates but function strictly as regulators of KATP channel activity. Currently, studies into the molecular basis by which various mutations in SUR2A cause disease are highly limited. This is primarily a consequence of poor solubility of isolated SUR2A NBDs, as is typical for many eukaryotic NBDs. By employing structure-based sequence alignments and biophysical studies, we determined domain boundaries for SUR2A NBD1 that enabled, for the first time, NMR studies of NBD1. Our biophysical studies demonstrate that the isolated SUR2A NBD1 is folded and exhibits differential dynamics upon ATP binding activity. Additional studies are now possible to examine the effects of disease-causing mutations on structure, dynamics, and interactions of NBD1.

The protein SiaA (Streptococcal iron acquisition) is involved in heme uptake in the bacterium Streptococcus pyogenes. It is difficult to obtain this protein in its fully holo form (completely loaded with heme). To increase the concentration of heme in the growing cell, we added ä-aminolevulinic acid (ALA) and ferrous sulfate (FeSO4), precursors of heme, to the growth media. Neither increasing the concentration of heme in vivo, nor growth at lower temperature for longer times, increased the production of holoprotein. The classical method of measuring the concentration of heme in a newly discovered heme protein is cumbersome. We have developed an improved method, which gives a solution that is more stable and has a cleaner spectrum. With further development, this new technique may replace the classical assay. Background information on S. pyogenes, SiaA, ABC transporters, heme biosynthesis, and the pyridine hemochrome assay are described.

Autism has been declared an urgent public health concern by the U.S. government and an epidemic by some advocacy groups. Determining autism’s diagnostic criteria, prevalence, and causes have been challenging. It is important to examine how the U.S. media have contributed to the public’s understanding of autism. Previous research found that British media coverage of the theory that vaccines cause autism was shown to contribute to the decline of vaccination rates in Britain (Lewis & Speers, 2003). This study examined U.S. television news media coverage using an agenda-setting theory and media framing perspective. A content analysis was conducted of national television evening news broadcasts airing on ABC, CBS, and NBC from 1994, when autism was first recognized as a spectrum disorder through April 2010, the time of this study. Specifically, this study examined the saliency of autism stories and how autism was framed in terms of prevalence and causes.

Thiamin transport in Escherichia coli is a model system to establish the tolerance of derivatives for transport into the cell. Since little is known about what types of thiamin derivatives may be successfully taken into the cell through the transport system, a series of thiamin derivatives are synthesized. A thiamin amino analog is synthesized and tested to determine the use of the analog as an alternate source of thiamin for growth of an E. coli thiamin mutant. Formate, acetate, and benzoate thiamin esters are synthesized and tested as alternate sources for growth of an E. coli thiamin mutant. Thiamin esters or amides may provide a scaffold for attaching other small molecules of interest to be imported into the cell by thiamin transport system. Thiamin containing formate, acetate, and benzoate esters were synthesized and tested as alternative growth source for thiamin using an E. coli mutant strain incapable of synthesizing thiamin. All three synthesized ester thiamin forms gave a zone of growth determined by disk-assay study. Also, an amino thiamin is synthesized to determine uptake through thiamin transport system by growth study using an E. coli mutant incapable of synthesizing thiamin. The growth curves resulting show concentration-dependent growth in the absence of natural thiamin, indicating amino thiamin is taken up by thiamin transport system as an alternate source of thiamin for growth. More characterization of the thiamin transport system is desired in order to develop thiamin conjugates of interest such as a photoaffinity probe for isolating thiamin-utilizing enzymes.

Lignin is a key component of plant secondary cell walls, providing strength to the plant and allowing water transport. Lignin is a polymer of monolignols that are synthesized in the cell and transported into the cellulose rich cell wall. The primary goal of this thesis is to understand the mechanism(s) of monolignol deposition during xylogenesis. The currently accepted theory is that monolignols are exported by Golgi-mediated vesicle delivery to the secondary cell wall. When this theory was re-examined using cryofixed developing pine, quantitative autoradiography showed that monolignols did not accumulate in Golgi but were rapidly translocated from cytosol to cell wall. This suggests alternative mechanisms, such as membrane transporters, work in monolignol export. ATP binding cassette (ABC) transporters were chosen because they transport other secondary metabolites and some ABC transporter encoding genes are highly expressed in lignifying cells. Four candidate ABC transporters were selected in Arabidopsis (ABCB11, ABCB14, ABCB15 from the ABCB/MDR subfamily and ABCG33 from the ABCG/PDR subfamily) and shown to have overlapping, high vasculature expression patterns. Mutants with T-DNA insertions in single ABC transporter genes had no change in lignification of inflorescence stems. However, a reduced polar auxin transport phenotype was detected in mutants of ABCB11, ABCB14 and ABCB15. An additional approach was the use of inhibitors of ABC transporters. A new assay, which was developed to quantify lignification in primary xylem of Arabidopsis roots, demonstrated that ABC inhibitors did not change lignin deposition. Monolignols are exported and polymerized in the polysaccharide matrix of the cell wall, which includes hemicelluloses that may organize monolignols during polymerization. Since diverse lignified cell types are enriched in either G- or S-lignin, I hypothesized that this pattern could reflect different hemicellulose distributions, which was examined using antibody labeling of xylans or mannans in hybrid poplar xylem. While xylans were generally distributed in all secondary cell walls, mannans were enriched in fibers but not in the ray and vessel walls. In summary, during secondary cell wall deposition, monolignols are exported by unknown transporter(s) rather than Golgi vesicles. In developing poplar wood, the monolignols are deposited into diverse hemicellulose domains in different cell types.