Browsing by Author "Cavaco, S."
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- Matrix gla protein in turbot (Scophthalmus maximus): gene expression analysis and identification of sites of protein accumulationPublication . Roberto, Vania Palma; Cavaco, S.; S B Viegas, Carla; Simes, D; Ortiz-Delgado, J. B.; Sarasquete, C.; Gavaia, Paulo J.; Cancela, LeonorMatrix Gla protein (Mgp) is a secreted vitamin K-dependent extracellular matrix protein and a physiological inhibitor of calcification whose gene structure, amino acid sequence and tissue distribution have been conserved throughout evolution. In the present work, the turbot (Scophthalmus maximus) mgp cDNA was cloned and the sequence of the deduced protein compared to that of other vertebrates. As expected, it was closer to teleosts than to other vertebrate groups but there was a strict conservation of amino-acids thought to be important for protein function. Analysis of mgp gene expression indicated branchial arches as the site with higher levels of expression, followed by heart, vertebra and kidney. These results were confirmed by in situ hybridization with a strong mgp expression in branchial arch chondrocytes. Mgp was found to accumulate in gills where it appeared to be restricted to chondrocytes from branchial filaments, while in vertebrae it was localized in vertebral end plates, in growth zones, in vertebral arches and spines and in notochord cells. In the soft tissues analysed, Mgp was mainly detected in kidney and heart, consistent with previous data and providing further evidence for a role of Mgp as a calcification inhibitor and a modulator of the mineralization process. Our studies provide evidence that turbot, an important new species for aquaculture, is also a useful model to study function and expression of Mgp.
- Mgp expression and accumulation in heart and kidney of turbot (Scophthalmus maximus)Publication . Roberto, Vania Palma; Cavaco, S.; Simes, D; Gavaia, Paulo J.; Cancela, LeonorMatrix γ-carboxyglutamic acid (Gla) protein (Mgp) is a vitamin K-dependent protein normally found associated with the organic matrix of cartilage and bone in vivo. After the discovery of Mgp in various soft tissues, this protein was proposed to act as a local inhibitor of mineralization although its molecular mechanisms of action remain incompletely understood.
- Teleost fish osteocalcin 1 and 2 share the ability to bind the calcium mineral phasePublication . Cavaco, S.; Williamson, M. K.; Rosa, Joana; Roberto, Vania Palma; Cordeiro, O.; Price, P. A.; Cancela, Leonor; Laizé, Vincent; Simes, DThe occurrence of a second osteocalcin (OC2) has been reported in teleost fish, where it coexists with OC1 in some species. While it has been proposed that OC2 gene originated from OC1 through the fish whole-genome duplication event, little information is available on its molecular function and physiological role. The present study brings biological data supporting the presence of OC2 in the mineral phase of teleost fish bone and its association with the mineral phase together with OC1. The occurrence of OC2 forms with different levels of phosphorylation or c-carboxylation, and with amino acid substitutions was observed. Comparative analysis of mature peptide sequences revealed the high conservation existing between OC1 and OC2, in particular within the core c-carboxyglutamic acid domain, and suggests that both protein forms may have the same function, i.e., binding of calcium ions or hydroxyapatite crystals.