Thesis (Ph. D.)--Case Western Reserve University, 2004. / [School of Medicine] Department of Neurosciences. Includes bibliographical references. Available online via OhioLINK's ETD Center.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2009. / Härtill 4 uppsatser.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 49-59). Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 49-59). Also available in print.

Cigarette smoke's influence on cancer has primarily been a subject of epidemilogic and tumorigenic studies. There have been no proper investigations with interests focused on how cigarette smoke affects the cellular mechanics of metastasis. Gathering an understanding of how smoke influences metastatic invasion could be vital in regulating or possibly eliminatings cancer's ability to initiate new tumor growth sites. This project focuses on cigarette smoke's influence on cellular mechanics of endothelial cells, and the invasive potential of cancer against a fully active endothelium. It is already known that cigarette smoke has a carcinogenic effect, but it is hypothesized that the cigarette smoke causes the endothelium to exhibit pro-invasive characteristics. Cancer cells are often ignorant to extra-cellular stimuli. It is suspected that there will be a less pronounced degradation of cellular mechanics of cancerous cells than endothelial cells when exposed to similar concentrations of cigarette smoke.

published_or_final_version / Biological Sciences / Master / Master of Philosophy

No description available.

Although dynamic interactions between plant cells and their environment require adhesion between the cell wall (CW) and the plasma membrane (PM), few plant adhesion molecules have been identified. Therefore, the seed coat mucilage secretory cells (MSCs) of Arabidopsis thaliana (which undergo developmentally regulated changes in adhesion) were developed into a novel model system to study PM-CW adhesion. Twenty-seven candidate genes were identified using data from publicly available and seed-specific microarrays. Mutant plants for these genes were screened for defects in adhesion via plasmolysis, and for changes in MSC morphology that may result from defective adhesion (Chapter 1). Two fasciclin-like arabinogalactan proteins were isolated in this screen. One of these, SOS5, was characterized in detail (Chapter 2). sos5 mutants are sensitive to hyperosmotic conditions and show defects in PM-CW adhesion and MSC mucilage structure. Interestingly, these phenotypes may be attributed to defects in adhesion or to defects in cell wall deposition.

In rheumatoid arthritis (RA), a key event is infiltration of inflammatory immune cells into the synovial lining, possibly aggravated by dysregulation of cellular adhesion molecules. Therefore, single nucleotide polymorphisms of 14 genes involved in cellular adhesion processes (CAST, ITGA4, ITGB1, ITGB2, PECAM1, PTEN, PTPN11, PTPRC, PXN, SELE, SELP, SRC, TYK2, and VCAM1) were analyzed for association with RA. Association analysis was performed consecutively in three European RA family sample groups (Nfamilies = 407). Additionally, we investigated differential allelic expression, a possible functional consequence of genetic variants. SELP (selectin P, CD62P) SNP-allele rs6136-T was associated with risk for RA in two RA family sample groups as well as in global analysis of all three groups (ptotal = 0.003). This allele was also expressed preferentially (p,1026) with a two- fold average increase in regulated samples. Differential expression is supported by data from Genevar MuTHER (p1 = 0.004; p2 = 0.0177). Evidence for influence of rs6136 on transcription factor binding was also found in silico and in public datasets reporting in vitro data. In summary, we found SELP rs6136-T to be associated with RA and with increased expression of SELP mRNA. SELP is located on the surface of endothelial cells and crucial for recruitment, adhesion, and migration of inflammatory cells into the joint. Genetically determined increased SELP expression levels might thus be a novel additional risk factor for RA.

The interaction mediated by integrin alphaLbeta2 and its ligand plays major role in many immune responses by regulating leukocyte adhesion. This study investigated the conformational regulation of alphaLbeta2 and the effects of conformational change on the ligand binding of alphaLbeta2. Micropipette adhesion frequency assay was used to measure the two-dimensional binding affinity and kinetics of alphaLbeta2 on K562 cells and neutrophils. The conformations of alphaLbeta2 were regulated by mutations, antibodies, small molecule antagonists, as well as divalent cations. Our results indicated that the change in binding affinity and off-rate was mostly due to the alphaL I domain conformational change. Without affecting the I domain conformation, the extension of alphaLbeta2 only increases the on-rate for several fold by providing a better orientation and accessibility of the molecule on cell surface. The binding characteristics of divalent cations to I domain MIDAS and other metal ion binding sites in alphaLbeta2 are determined by the nature of divalent cations, Mn2+ has higher binding affinity to the metal ion binding sites than Mg2+. The conformation of I domain also affected the binding of divalent cations. Open and intermediate I domains have higher binding affinity for Mn2+ and Mg2+ than WT and closed I domains. Divalent cations dissociate from I domain MIDAS very slowly but from those metal ion binding sites that important for conformational change of alphaLbeta2 rapidly. One of the most important biological processes mediated by alphaLbeta2 and other beta2 integrins is the recruitment and migration of neutrophils during inflammation. The activation of beta2 integrins by E-selectin binding to neutrophils in this process was also investigated. The binding of E-selectin, but not P- or L-selectin, activates beta2 integrins in a timescale of ~ 5 seconds and the activation may require the crosslink of E-selectin ligands. These results provide insights into the relationship between the conformational change and the function of alphaLbeta2 and most importantly would contribute to the understanding of integrin regulation mechanisms.