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Structural Association (structural + association)
Selected AbstractsNeovascularization and mast cells with tryptase activity increase simultaneously in human pterygiumJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2007Domenico Ribatti Abstract Mast cells (MC) have been implicated in both normal and pathological angiogenesis, such as that in chronic inflammatory diseases and tumors. This assumption is partially supported by the close structural association between MC and blood vessels and the recruitment of these cells during tumor growth. MC release a number of angiogenic factors among which tryptase, a serine protease stored in MC granules, is one of the most active. In this study, we correlate the extent of angiogenesis with the number of tryptase-reactive MC in tissue fragments from pterygium and normal bulbar conjunctiva investigated by immunohistochemistry, using two murine monoclonal antibodies against the endothelial cell marker CD31 and the MC marker tryptase. Angiogenesis, measured as microvessel density, was highly correlated with MC tryptase-positive cell count in pterygium tissues. These results suggest that the characteristic neovascularization observed in pterygium may be sustained, at least in part, by MC angiogenic mediators, in particular tryptase. [source] Vascular Mimicry of Granulosa Cells: a New Concept of Corpeus Luteum Development?ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005R. M. Hirschberg So far, it was generally accepted that newly formed blood vessels are exclusively comprised of endothelial cells, and complemented by pericyte and myocyte recruitment during vessel maturation. Accordingly, participation of non-endothelial cells in the formation of blood vessels has rarely been suggested. Recently, evidence supporting the existence of tumour vessels lined by non-endothelial cells has emerged. Consequently, the concept of the inherent capacity of non-endothelial cells to behave like endothelial cells has been discussed for tumours, and this pathomechanism has been termed vascular mimicry. The corpus luteum is one of the most intensely vascularized tissues, and angiogenesis in the corpus luteum is more effective than in highly malignant tumours. Our results indicate active involvement of granulosa cells in luteal angiogenesis, and the aim of this study was to shed more light on this exciting prospect. The study was based on cultured granulosa cells isolated from the bovine ovary in different stages of follicle maturation. Morphology of angiogenic granulosa cells was studied by phase contrast, transmission electron and scanning electron microscopy. Expression of angiogenesis-regulating factors and their receptors was demonstrated by polymerase chain reaction (RT-PCR). Cultured granulosa cells underwent changes reminiscent of endothelial angiogenesis, i.e., migration, proliferation, differentiation and three-dimensional organization, and expressed angiogenesis-regulating factors and their receptors. Our results suggest a tight regulatory and structural association of endothelial and granulosa cells in luteal angiogenesis, suggesting physiological vascular mimicry in the ovary. [source] The endoproteinase furin contains two essential Ca2+ ions stabilizing its N-terminus and the unique S1 specificity pocketACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2005Manuel E. Than The mammalian prohormone/proprotein convertase (PC) furin is responsible for the maturation of a great variety of homeostatic but also many pathogenic proteins within the secretory pathway and the endosomal pathway and at the cell surface. Similar to other members of the PC family, furin requires calcium for catalytic activity. In a previous paper, the structural association of the catalytic and the P-domain of furin was shown and data were presented indicating two or three calcium-binding sites. The exact number and the three-dimensional localization of the essential calcium sites within furin have now been determined by collecting X-ray diffraction data on either side of the Ca,K absorption edge and by calculating a novel type of double difference map from these anomalous scattering data. Two calcium ions were unambiguously identified: the purely structural Ca-1 also conserved in the bacterial digestive subtilisins and the Ca-2 site specific to PCs and essential for the formation of the P1 specificity-determining S1-binding pocket. In addition, these anomalous diffraction data show that no tightly bound K+ sites exist in furin. [source] An in silico method using an epitope motif database for predicting the location of antigenic determinants on proteins in a structural contextJOURNAL OF MOLECULAR RECOGNITION, Issue 1 2006Vincent Batori Abstract Presently X-ray crystallography of protein,antibody complexes is still the most direct way of identifying B-cell epitopes. The objective of this study was to assess the potential of a computer-based epitope mapping tool (EMT) using antigenic amino acid motifs as a fast alternative in a number of applications not requiring detailed information, e.g. development of pharmaceutical proteins, vaccines and industrial enzymes. Using Gal d 4 as a model protein, the EMT was capable of identifying, in the context of the folded protein, amino acid positions known to be involved in antibody binding. The high sensitivity and positive predictive value of the EMT as well as the relevance of the structural associations suggested by the EMT indicated the existence of amino acid motifs that are likely to be involved in antigenic determinants. In addition, differential mapping revealed that sensitivity and positive predictive value were dependent on the minimum relative surface accessibility (RSA) of the amino acids included in the mapping, demonstrating that the EMTs accommodated for the fact that epitopes are three-dimensional entities with various degrees of accessibility. The comparison with existing prediction scales demonstrated the superiority of the EMT with respect to physico-chemical scales. The mapping tool also performed better than the available structural scales, but the significance of the differences remains to be established. Thus, the EMT has the potential of becoming a fast and simple alternative to X-ray crystallography for predicting structural antigenic determinants, if detailed epitope information is not required. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||