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<p> Mre11 and Rad50 form a complex with Nbs1 (MRN) in mammals and Xrs2 (MRX) in yeast. The MRN complex plays a role in many cellular processes, such as DNA damage sensing, DNA repair, cell cycle checkpoint and telomere maintenance. Rad50 contains a conserved ATP binding motif and its ATPase activity is essential for ATM activation in vitro. Using a tethering approach, I have shown that Rad50 can be targeted to telomeres through its fusion to hRap1. The fusion of hRap1 to Rad50 did not alter the property of Rad50. The fused wild-type Rad50 promoted telomerase-dependent telomere lengthening. However, the fusion proteins containing loss-of-function mutations in Rad50 (K42E and S1202R) did not. I have also shown that the fused wild-type Rad50 was able to form irradiation-induced foci in a manner similar to unfused Rad50. In contrast, the two defective mutants of Rad50 failed to accumulate irradiation-induced foci. Expression of the fusion proteins containing Rad50 mutants also interfered with the ability of endogenous Mre11 protein to form foci post irradiation. Thus our data suggest that the Rad50 mutants may function as dominant-negative alleles in cells.</p> / Thesis / Master of Science (MSc)

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2005. / Härtill 4 uppsatser.

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

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 3 uppsatser.

Expression of sTGFbetaRII-Fc-Jun from recombinant vaccinia virus TGFß has a biphasic role in tumorigenesis. In early phases it acts as tumor sup-pressor. However, in late phases when cells have escaped selectively from the antimito-genic response of TGFß, it may act as a promoter of tumor progression and invasion. One way of control tumor formation and progression is blocking of TGFß signalling pathways in late phases of tumorigenesis. We have constructed recombinant vaccinia virus P13 expressing soluble TGFbeta type II receptor fused with the Fc fragment of IgG1 and with Jun fragment (sTbetaRII-Fc-Jun). This sTbetaRII-Fc-Jun is supposed to increase the effect of antitumor vaccinia virus vaccine expressing SigE7LAMP, which is investigated for the treatment of the HPV-16 associated cervical cancer. Binding of sTbetaRII-Fc-Jun to protein G were tested by SDS-PAGE and by im-munoblotting. We found that Jun fragment and sTbetaRII fragment do not block Fc bind-ing site for protein G. sTbetaRII-Fc-Jun was characterised using SDS-PAGE and immunoblot analysis. We observed that the amount of sTbetaRII-Fc-Jun was higher in cell supernatans of in-fected cells in comparison to cell lysates. In cell lysates we observed higher amount of sTbetaRII than sTbetaRII-Fc-Jun. The expression of sTbetaRII-Fc-Jun was stronger under...

The chicken BG system is a highly polymorphic and polygenic multigene family encoding type I transmembrane proteins, with butryophilins as homologues in mammals, some of which are crucial in T cell regulation. There are three genomic locations where BG genes are found: one singleton BG gene (BG0) on chromosome 2, another singleton gene (BG1) in BF-BL region (the so-called minimal essential chicken MHC) on chromosome 16, and many BG genes arranged tandemly in the BG region just outside the MHC. BG genes in BG region have copy number variation between different chicken haplotypes, so it has been unclear which BG genes are alleles, as very little sequence information has been available for haplotypes other than B12, the best characterized one. Also, the functions of chicken BG genes have been a mystery for half a century, although there is evidence for cytoskeletal regulation and for viral disease resistance. Therefore, the aim of the research was to develop new procedures and reagents to understand the BG system. A novel PCR protocol was established to overcome the difficulty of amplifying full length polymorphic BG transcripts, and then was applied to systematically examine the BG cDNA sequences from T cells and B cells of four different chicken haplotypes. In total 23 BG genes were found, most with alternative splicing isoforms; most strikingly, the transcripts potentially encoding soluble BG proteins were only seen in B cells, indicating functional differences of the same gene in T and B cells. By comparing the dominantly expressed BG genes as 'functional alleles' in these cells, only the cytoplasmic tail region is clearly seen to be under selection, based on the overwhelming preponderance of non-synonymous changes. With many other unexpected findings discovered in this project, a clearer picture of chicken BG genes is presented, and more questions were raised for future study. In order to explore BG functions and further characterize BG proteins, fourteen stable cell lines were developed expressing fusion proteins of the Ig-V domains of the 14 BG genes from the B12 haplotype chicken with the human IgG1 Fc fragment. These BG-Fc fusion proteins were used in sandwich enzyme-linked immunosorbent assays (ELISAs) to screen 290 BG monoclonal antibody (mAb) tissue culture supernatants, and these BG mAbs were further characterized for specificity by western blot using BG-Fc fusion proteins. These solid tools (BG-Fc fusion proteins and BG mAbs) provide the basis to further understand chicken BG functions and answer other interesting questions.

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

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 6 uppsatser.

Thesis (M.S.)--University of Tennessee Health Science Center, 2008. / Title from title page screen (viewed on January 6, 2009). Research advisor: Charles J. Russell, Ph.D. Document formatted into pages (ix, 41p. : ill.). Vita. Abstract. Includes bibliographical references (p. 38-41).