The mitotic checkpoint blocks cell cycle progression before anaphase in case of mistakes in the alignment of chromosomes on the mitotic spindle. In budding yeast, the Mad1, 2, 3, and Bub1, 2, 3 proteins mediate this arrest. Vertebrate homologues of Mad1, 2, 3, and Bub1, 3 bind to unattached kinetochores and prevent progression through mitosis by inhibiting Cdc20/APC-mediated proteolysis of anaphase inhibitors, like Pds1 and B-type cyclins. We investigated the role of Bub2 in budding yeast mitotic checkpoint. The following observations indicate that Bub2 and Mad1, 2 probably activate the checkpoint via different pathways: (a) unlike the other Mad and Bub proteins, Bub2 localizes at the spindle pole body (SPB) throughout the cell cycle; (b) the effect of concomitant lack of Mad1 or Mad2 and Bub2 is additive, since nocodazole-treated mad1 bub2 and mad2 bub2 double mutants rereplicate DNA more rapidly and efficiently than either single mutant; (c) cell cycle progression of bub2 cells in the presence of nocodazole requires the Cdc26 APC subunit, which, conversely, is not required for mad2 cells in the same conditions. Altogether, our data suggest that activation of the mitotic checkpoint blocks progression through mitosis by independent and partially redundant mechanisms.

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The glomerular mesangial cells (GMC) play a central role in the synthesis and turnover of the glomerular mesangial matrix. The breakdown of the matrix likely depends on the balance between a variety of proteinases including matrix metalloproteinases and their biological inhibitors secreted by the GMC. Therefore, we studied pattern secretion of matrix metalloproteinases (MMPs), MMP-1, MMP-2, MMP-3, MMP-9 and their biological tissue inhibitor of matrix metalloproteinases (TIMPs), TIMP-1 and TIMP-2 by cultured human GMC. We also measured MMP-l/TIMP-1 complex level in the cell culture supernatants. For this purpose, the GMC were incubated under serum-free conditions with medium (RPMI-1640) alone or in combination with TNF-alpha (30 ng/ml) or PMA (50 ng/ml) for 24,48 and 72 h. The metalloproteinases and their inhibitors were assayed by established ELISA techniques. Our results showed that the lowest and largest secretions were related to MMP-9 and MMP-2, respectively. The results indicated that the MMPs and TIMPs secretion were increased by TNF-alpha (MMP-1, MMP-2, TIMP-1 and TIMP-2) and PMA (MMP-2, TIMP-1 and TIMP-2), significantly (P < 0.05). These results suggest that GMC can synthesis and release various MMPs and their inhibitors (TIMPs) that, in part, control turnover of extracellular matrix proteins.An increased burden of oxidants and depletion of antioxidant defenses may contribute to the age-related decline in adrenal steroidogenesis. I n this study, we sought to determine whether aging influences the sensitivity of the adrenal to LPSstress related activation of NF-kB, a redox-sensitive transcription factor. Young mature (5 mo) and old (24-26 mo) rats were injected without or with LPS and nuclear extracts studied using electrophoretic mobility shift assay (EMSA) andWestern blotting. The adrenals from old animals showed -50% reduction in activation of NF-kB D N A binding activity as determined by EMSA, when treated with LPS as compared to values from the adrenals of young animals. Supershift analysis confirmed the presense of p65 and p50 proteins in D N A complexes. Aging decreased both total and nuclear levels of p65, but had no effect o n IkB inhibitory proteins. These findings suggest that aging-induced increases in oxidative stress might be related to alterations in NF-kB signaling, which could contribute to the adverse affects of aging on adrenal steroidogenesis. Desulfovibrio gigus is a sulphate reducing bacterium, very rich in several proteins involved in oxido-reduction reactions. These proteins show a great variety of prosthetic groups, playing an important role in the biochemical understanding of this bacterium. Some of these proteins are very well characterized, however, the function of many remains unclear. The recombinant overexpressed proteins help us to get information on its function and structure. One of these important proteins is the flavoredoxin. Flavoredoxin is a FMN binding protein that participates in the reduction of bisulphite from molecular hydrogen. According to the significant homolo...