Biomoleculaire dans van leven, ziekte en dood

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Stem-loop structures can effectively substitute for an RNA pseudoknot in-1 ribosomal frameshifting

Biophysical Structural ChemistrySupramolecular & Biomaterials Chemistr

Apoptin Induces Tumor specific Apoptosis as a Globular Multimer

Biofysische structuurchemi

Importance of nuclear localization of apoptin for tumor-specific induction of apoptosis

Biofysische structuurchemi

Apoptin Enhances Radiation-Induced Cell Death in Poorly Responding Head and Neck Squamous Cell Carcinoma Cells

Treatment of head and neck cancers is still rather poor and worldwide new treatment options are sought. Sensitizing radioresistant tumours by combining irradiation with other therapeutics to induce apoptosis are widely investigated. We examined whether chicken anaemia virus-derived apoptin protein would have a beneficial effect on irradiation of radiosensitive SCC61 and radioresistant SQD9 human head and neck squamous carcinoma cell lines. In both cell lines, concurrent exposure to irradiation and apoptin resulted in analysed mitochondrial cytochrome c release and in cleavage of caspase-3, whereas irradiation alone of SQD9 cells under identical conditions did not. Moreover, in comparison with the irradiation, only the synchronized treatment of apoptin and irradiation resulted in increased cell death in especially the radioresistant SQD9 cells, as measured by means of a colony survival assay. Our data reveal that apoptin treatment represents an effective way for enhancing radiotherapy of tumours responding poorly to radiotherapy.Experimental cancer immunology and therap

Apoptin’s functional N- and C-termini independently bind DNA

AbstractApoptin induces apoptosis specifically in tumour cells, where Apoptin is enriched in the DNA-dense heterochromatin and nucleoli. In vitro, Apoptin interacts with dsDNA, forming large nucleoprotein superstructures likely to be relevant for apoptosis induction. Its N- and C-terminal domains also have cell-killing activity, although they are less potent than the full-length protein. Here, we report that both Apoptin’s N- and C-terminal halves separately bound DNA, indicating multiple independent binding sites. The reduced cell killing activity of both truncation mutants was mirrored in vitro by a reduced affinity compared to full-length Apoptin. However, none of the truncation mutants cooperatively bound DNA or formed superstructures, which suggests that cooperative DNA binding by Apoptin is required for the formation of nucleoprotein superstructures. As Apoptin’s N- and C-terminal fragments not only share apoptotic activity, but also affinity for DNA, we propose that both properties are functionally linked

Immunogenic and protective properties of chicken anaemia virus proteins expressed by baculovirus

The coding information for three putative chicken anaemia virus proteins (VP1, VP2, VP3) was inserted into a baculovirus vector and expressed in insect cells. The immunogenic properties of the chicken anaemia virus (CAV) proteins produced separately or together in insect-cell cultures were analysed by inoculating them into chickens. Only lysates of insect cells which have synthesised equivalent amounts of all three recombinant CAV proteins or cells which synthesised mainly VP1 plus VP2 induced neutralising antibodies directed against CAV in inoculated chickens. Progeny of those chickens were protected against clinical disease after CAV challenge. Inoculation of a mixture of lysates of cells that were separately infected with VP1-, VP2- and VP3-recombinant baculovirus did not induce significant levels of neutralising antibody directed against CAV and their progeny were not protected against CAV challenge. Our results indicate that expression in the same cell of at least two CAV proteins, VP1 plus VP2, is required to obtain sufficient protection in chickens. Therefore, recombinant CAV proteins produced by baculovirus vectors can be used as a sub-unit vaccine against CAV infections