Antisense oligonucleotides are short strands of DNA, which bind to their complementary mRNA target to prevent protein translation. Although conceptually appealing, for their practical use as drugs, these oligonucleotides must have better cellular uptake, resistance to enzymatic degradation, and target selectivity. In this work, new synthetic chemistry is established to prepare a novel group of chemically modified oligonucleotides. The anionic phosphodiester backbone is partially replaced with a neutral triazole and, at the same time, the 2'-position of the ribose sugar is functionalised with pyrene, anthraquinone, or guanidine moieties. Being unnatural, the triazole backbone is inherently resistant to enzymatic degradation, while the reduced negative charge potentially improves cell penetration. The limitation of introduction of a triazole backbone into the antisense strand is its destabilising effect on the duplex formation with their complementary target. In this study, the 2'-modifications are used to restore the lost duplex stability and they have been found to be very efficient stabilising moieties. To evaluate the viability of this strategy, reporter gene assays based on splice-switching model are used. Promisingly, these modified oligonucleotides have successfully shown antisense splice-switching activity, suggesting there is further scope for their improvement.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2000. / Includes bibliographical references.

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Graduation date: 1991

Functional inactivation of tumor susceptibility gene tsg101 leads to cellular transformation and tumorigenesis in mice. No genomic DNA deletion in TSG101gene in human cancer indicated TSG101 is not a typical tumor suppressive gene. TSG101 participates in the MDM2/p53 feedback control loop and the regulation of the cellular membrane trafficking. However, detail functional characteristics remains to be elucidate. In this study, we explored the tsg101 expression in adult mouse tissues from various organs using immunohistochemistry and in situ hybrid- ization. The results indicated that tsg101 expression was ubiquitous but in differential steady-state level in various cell types. The expression of tsg101 mainly found in epithelial cells¡Bsecretory cells and nerve cells. The second topic of this study was to characterize the phosphorylation status of TSG101 protein. Endogeneously expressed TSG101 and exogeneously expressed HA-tag TSG101 protein were purified by immunoprecipiation with #820 antiserum against TSG101, and were subjected for western blot analysis using anti-phosphoserine and anti-phosphothreonine antibodies. This experiment had confirmed that TSG101 protein contained both phosphoserine and phosphthreonine residues. In vitro kianse assay using GST-tag and his-tag TSG101 funsion proteins was exploited to investigate the kinase responsible for TSG101 phosphorylation. The results clearly indicated that cdc2¡BGSK3£] and PKC kinases could phosphorylate TSG101 fusion Protein, implying that the function of TSG101 might be regulated by the signaling involving these kinases.