Loading...
5 results
Search Results
Now showing 1 - 5 of 5
- Antioxidant, mineralogenic and osteogenic activities of Spartina alterniflora and Salicornia fragilis extracts rich in polyphenolsPublication . Roberto, Vania Palma; Surget, Gwladys; Le Lann, Klervi; Mira, Sara; Tarasco, Marco; Guérard, Fabienne; Poupart, Nathalie; Laizé, Vincent; Stiger-Pouvreau, Valérie; Cancela, M. LeonorOsteoporosis is an aging-related disease and a worldwide health issue. Current therapeutics have failed to reduce the prevalence of osteoporosis in the human population, thus the discovery of compounds with bone anabolic properties that could be the basis of next generation drugs is a priority. Marine plants contain a wide range of bioactive compounds and the presence of osteoactive phytochemicals was investigated in two halophytes collected in Brittany (France): the invasive Spartina alterniflora and the native Salicornia fragilis. Two semi-purified fractions, prepared through liquid-liquid extraction, were assessed for phenolic and flavonoid contents, and for the presence of antioxidant, mineralogenic and osteogenic bioactivities. Ethyl acetate fraction (EAF) wasrich in phenolic compounds and exhibited the highest antioxidant activity. While S. fragilis EAF only triggered a weak proliferative effect in vitro, S. alterniflora EAF potently induced extracellular matrix mineralization (7-fold at 250µg/mL). A strong osteogenic effect was also observed in vivo using zebrafish operculum assay (2.5-fold at 10µg/mL in 9-dpf larvae). Results indicate that polyphenol rich EAF of S. alterniflora has both antioxidant and bone anabolic activities. As an invasive species, this marine plant may represent a sustainable source of molecules for therapeutic applications in bone disorders.
- The xenobiotic sensor PXR in a marine flatfish species (Solea senegalensis): Gene expression patterns and its regulation under different physiological conditionsPublication . Marques, Carlos; Roberto, Vania Palma; Granadeiro, Luis; Trindade, Marlene; Gavaia, Paulo; Laizé, Vincent; Leonor Cancela, M.; Fernandez, IgnacioThe pregnane X receptor (PXR) is a nuclear receptor belonging to the NR1I sub-family and a known master regulator of xenobiotic metabolism. New roles have been recently proposed in mammals through its activation by vitamin K (VK) such as regulation of glucose metabolism, bone homeostasis, reproduction, neuronal development and cognitive capacities. In marine fish species little is known about PXR and its potential roles. Here, expression patterns of pxr transcripts and conservation of protein domains were determined in the Senegalese sole (Solea senegalensis), a marine flatfish model species in aquatic ecotoxicology. In addition to a full coding sequence transcript (sspxrl), two variants lacking DNA and/or ligand binding domains (sspxr2 and sspxr3) were also identified. The expression of sspxrl during early development and in adult tissues was ubiquitous, but highest levels were observed in liver, intestine and skin. Expression was also detected by in situ hybridization in chondrocytes and cells from the granular and inner nuclear layers in three month old fish. Finally, sspxrl expression was shown to be differentially regulated under physiological conditions related with fasting, VK and warfarin metabolism. The present work provides new and basic knowledge regarding pxr sequence and expression patterns in a marine flatfish species to unveil the potential impact of xenobiotics on marine fish physiology, and will allow a better and more ecosystemic environmental risk assessment of different pollutants over the marine environments with the development of reporter assays using PXR sequences from evolutionary distantly marine species (such as vertebrate and invertebrate marine species). (C) 2017 Elsevier Ltd. All rights reserved.
- 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.
- Marine green macroalgae: a source of natural compounds with mineralogenic and antioxidant activitiesPublication . Surget, Gwladys; Roberto, Vania Palma; Le Lann, Klervi; Mira, Sara; Guerard, Fabienne; Laizé, Vincent; Poupart, Nathalie; Leonor Cancela, M.; Stiger-Pouvreau, ValerieMarine macroalgae represent a valuable natural resource for bioactive phytochemicals with promising applications in therapeutics, although they remain largely under-exploited. In this work, the potential of two marine green macroalgae (Cladophora rupestris and Codium fragile) as a source of bioactive phenolic compounds was explored, and antioxidant, mineralogenic, and osteogenic activities were evaluated. For each species, a crude hydroalcoholic extract (CE) was prepared by solid/liquid extraction and fractionated by liquid/liquid purification into an ethyl acetate fraction (EAF) enriched in phenolic compounds and an aqueous fraction (AF). Antioxidant activity, assessed through radical scavenging activity and reducing power assay, was increased in EAF fraction of both species and closely related to the phenolic content in each fraction. Mineralogenic activity, assessed through extracellular matrix mineralization of a fish bone-derived cell line, was induced by EAF fractions (up to 600 % for C. rupestris EAF). Quantitative analysis of operculum formation in zebrafish larvae stained with alizarin red S further confirmed the osteogenic potential of EAF fractions in vivo, with an increase of more than 1.5-fold for both C. fragile and C. rupestris fractions, similar to vitamin D (control). Our results demonstrated a positive correlation between phenolic fractions and biological activity, suggesting that phenolic compounds extracted from marine green macroalgae may represent promising molecules toward therapeutic applications in the field of bone biology.
- Mir-20a regulates in vitro mineralization and BMP signaling pathway by targeting BMP-2 transcript in fishPublication . Tiago, Daniel; Marques, C. L.; Roberto, Vania Palma; Cancela, Leonor; Laizé, VincentMicroRNAs (miRNAs) are important regulators of vertebrate development but their role during skeletogenesis remains unknown. In this regard, we investigated the mineralogenic activity of miR-20a, a miRNA associated with osteogenesis, in fish bone-derived cells. Expression of miR-20a was up-regulated during differentiation and its overexpression inhibited mineralization, suggesting a role in fish tissue calcification. In this regard, a conserved miR-20a binding site was identified in bone morphogenetic protein 2 (BMP-2) 30UTR and its functionality was evidenced through luciferase assays, and further confirmed by western-blot and qPCR. Type II BMP receptor (BMPR2) is also targeted by miR-20a in mammalian systems and evidence was collected for the presence of a binding site in fish sequences. We propose that miR-20a is a regulator of BMP pathway through specific action on BMP-2 and possibly BMPR2. Overexpression of miR-20a was also shown to up-regulate matrix Gla protein (MGP) transcript, a physiological inhibitor of calcification previously found to form a complex with BMP-2. We propose that MGP may play a role in the anti-mineralogenic effect promoted by miR-20a by decreasing availability of BMP-2. This study gives new insights into miRNA-mediated regulation of BMP-2, and sheds light into the potential role of miR-20a as a regulator of skeletogenesis.