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- Kiseleva, E. P., et al.
(författare)
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Isolation and structural identification of glycopolymers of Bifidobacterium bifidum BIM B-733D as putative players in pathogenesis of autoimmune thyroid diseases
- 2013
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Ingår i: Beneficial microbes. - 1876-2891. ; 4:4, s. 375-391
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Tidskriftsartikel (refereegranskat)abstract
- Bifidobacterium bifidum 791 (commercially available as B. bifidum BIM B-733D) cell-surface biopolymers (BPs) interact selectively with human serum thyroid peroxidase (TPO) and thyroglobulin (Tg) autoantibodies (anti-TPO and anti-Tg, respectively). BPanti-TPO and BPanti-Tg were isolated from the soluble fraction of B. bifidum BIM B-733D by affinity chromatography with anti-TPO or anti-Tg, respectively. Homogeneity of affinity eluates (AE(anti-TPO) and AE(anti-Tg)) was tested by size exclusion chromatography. For each AE, the elution profiles generated on the basis of absorbance at 280 nm do not conform to ELISA data for functional activity characteristic of BPs. Moreover, high functional activity was detected in chromatographic fractions that had significantly different molecular weights and no absorbance at 280 nm, which suggests a non-protein (carbohydrate) nature of BPanti-TPO and BPanti-Tg. The semi-preparative size exclusion chromatography of AE(anti-TPO) and AE(anti-Tg) with detection by refractometer gave 5,000-7,000 Da fractions containing substances that interact selectively with either anti-TPO (BPanti-TPO) or anti-Tg (BPanti-Tg) according to ELISA data. Analysis by two-dimensional NMR spectroscopy including a H-1, C-13-heteronuclear single-quantum coherence experiment indicated that both substances are linear alpha-1,6-glucans. For the first time, an immunological similarity (molecular mimicry) of glycopolymers of B. bifidum BIM B-733D and human thyroid proteins, TPO and Tg, was shown. On the whole, our data point to a possible role of bifidobacteria in the pathogenesis of autoimmune thyroid diseases (ATD). The main requirements for triggering/acceleration or prevention/abrogation of ATD by bifidobacteria through molecular mimicry mechanism are hypothesised to be (1) genetic predisposition to ATD and (2) intestinal epithelium penetration by alpha-1,6-glucan.
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- AlzhanovaEricsson, AT, et al.
(författare)
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A protein of the SR family of splicing factors binds extensively to exonic Balbiani ring pre-mRNA and accompanies the RNA from the gene to the nuclear pore
- 1996
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Ingår i: Genes & development. - : Cold Spring Harbor Laboratory. - 0890-9369 .- 1549-5477. ; 10:22, s. 2881-2893
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Tidskriftsartikel (refereegranskat)abstract
- We report on the molecular cloning and intracellular localization of a heterogeneous nuclear ribonucleoprotein (hnRNP), Ct-hrp45, one of the major components of pre-mRNP particles in Chironomus tentans. It is shown that hrp45 belongs to the SR family of splicing factors and exhibits high sequence similarity to Drosophila SRp55/B52 and human SF2/ASF. The distribution of hrp45 within the C. tentans salivary gland cells is studied by immunocytology. The hrp45 protein is found to be abundant in the nucleus, whereas it is undetectable in the cytoplasm. The fate of hrp45 in specific pre-mRNP particles, the Balbiani ring (BR) granules, is revealed by immunoelectron microscopy. It is observed that hrp45 is associated with the growing BR pre-mRNP particles and is being added continuously concomitant with the growth of the transcript, indicating that hrp45 is bound extensively to exon 4, which comprises 80-90% of the primary transcript. Furthermore, hrp45 remains bound to the BR RNP particles in the nucleoplasm and is not released until the particles translocate through the nuclear pore. Thus, hrp45 behaves as an hnRNP protein linked to exon RNA (and perhaps also to the introns) rather than as a spliceosome component connected to the assembly and disassembly of spliceosomes. It seems that hrp45, and possibly also other SR family proteins, is playing an important role in the structural organization of pre-mRNP particles and is perhaps participating not only in splicing but also in other intranuclear events.
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- Onischenko, Evgeny A, et al.
(författare)
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Cdk1 and okadaic acid-sensitive phosphatases control assembly of nuclear pore complexes in Drosophila embryos
- 2005
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Ingår i: Molecular Biology of the Cell. - 1059-1524 .- 1939-4586. ; 16:11, s. 5152-5162
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Tidskriftsartikel (refereegranskat)abstract
- Disassembly and reassembly of the nuclear pore complexes (NPCs) is one of the major events during open mitosis in higher eukaryotes. However, how this process is controlled by the mitotic machinery is not clear. To investigate this we developed a novel in vivo model system based on syncytial Drosophila embryos. We microinjected different mitotic effectors into the embryonic cytoplasm and monitored the dynamics of disassembly/reassembly of NPCs in live embryos using fluorescently labeled wheat germ agglutinin (WGA) or in fixed embryos using electron microscopy and immunostaining techniques. We found that in live embryos Cdk1 activity was necessary and sufficient to induce disassembly of NPCs as well as their cytoplasmic mimics: annulate lamellae pore complexes (ALPCs). Cdk1 activity was also required for keeping NPCs and ALPCs disassembled during mitosis. In Agreement recombinant Cdk1/cyclin B was able to induce phosphorylation and dissociation of nucleoporins from the NPCs in vitro. Conversely, reassembly of NPCs and ALPCs was dependent on the activity of protein phosphatases, sensitive to okadaic acid (OA). Our findings suggest a model where mitotic disassembly/reassembly of the NPCs is regulated by a dynamic equilibrium of Cdk1 and OA-sensitive phosphatase activities and provide evidence that mitotic phosphorylation mediates disassembly of the NPC.
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