Structural and functional properties of the capsid protein of Dengue and related Flavivirus

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Dengue, West Nile and Zika, closely related viruses of the Flaviviridae family, are an increasing global threat, due to the expansion of their mosquito vectors. They present a very similar viral particle with an outer lipid bilayer containing two viral proteins and, within it, the nucleocapsid core. This core is composed by the viral RNA complexed with multiple copies of the capsid protein, a crucial structural protein that mediates not only viral assembly, but also encapsidation, by interacting with host lipid systems. The capsid is a homodimeric protein that contains a disordered N-terminal region, an intermediate flexible fold section and a very stable conserved fold region. Since a better understanding of its structure can give light into its biological activity, here, first, we compared and analyzed relevant mosquito-borne Flavivirus capsid protein sequences and their predicted structures. Then, we studied the alternative conformations enabled by the N-terminal region. Finally, using dengue virus capsid protein as main model, we correlated the protein size, thermal stability and function with its structure/dynamics features. The findings suggest that the capsid protein interaction with host lipid systems leads to minor allosteric changes that may modulate the specific binding of the protein to the viral RNA. Such mechanism can be targeted in future drug development strategies, namely by using improved versions of pep14-23, a dengue virus capsid protein peptide inhibitor, previously developed by us. Such knowledge can yield promising advances against Zika, dengue and closely related Flavivirus.This work was supported by “Fundação para a Ciência e a Tecnologia–Ministério da Ciência, Tecnologia e Ensino Superior” (FCT-MCTES, Portugal) project PTDC/SAU-ENB/117013/2010, Calouste Gulbenkian Foundation (FCG, Portugal) project Science Frontiers Research Prize 2010. A.F.F., A.S.M. and J.C.R. also acknowledge FCT-MCTES fellowships SFRH/BD/77609/2011, PD/BD/113698/2015 and SFRH/BD/95856/2013, respectively. I.C.M. acknowledges FCT-MCTES Programs “Investigador FCT” (IF/00772/2013) and “Concurso de Estímulo ao Emprego Científico” (CEECIND/01670/2017). This work was also supported by UID/BIM/50005/2019, project funded by Fundação para a Ciência e a Tecnologia (FCT)/ Ministério da Ciência, Tecnologia e Ensino Superior (MCTES) through Fundos do Orçamento de Estado.info:eu-repo/semantics/publishedVersio

Linking Wnt pathway with bone mineralization and fracture risk in osteoporosis

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2015A osteoporose caracteriza-se por uma baixa densidade mineral óssea e deterioração da micro-arquitectura óssea trabecular, predispondo a ocorrência de fracturas. Este estudo pretendeu comparar a expressão de genes de remodelação óssea, nomeadamente a via Wnt, entre doentes com fractura de fragilidade e com osteoartrose submetidos a artroplastia total da anca e ainda compreender a variação pós-fractura dos reguladores dessa via. Os resultados da expressão genética mostraram um aumento da diferenciação dos osteoblastos, mas alterações na maturação final dos osteoblastos assim como um aumento da osteoclastogénese favorecem a reabsorção óssea nos doentes com fractura de fragilidade. Quanto à via Wnt, ambos os grupos demonstraram um aumento na expressão de antagonistas desta via, particularmente a SOST para doentes com fractura de fragilidade e WIF e DKK1 (apoiado por resultados de imunohistoquímica) para doentes com osteoartrose. Ainda se verificou uma diminuição na expressão destes inibidores durante a fase inicial pós-fractura. Conclui-se, portanto, que, no grupo das fracturas de fragilidade, alterações na osteoblastogénese potenciadas pelo aumento de antagonistas da via Wnt conduzem a maior susceptibilidade a fracturas, sendo que a redução da sua expressão pode ser um passo fundamental para o processo de regeneração pós-fractura.Osteoporosis is characterized by low bone mineral density and microarchitectural deterioration of the trabecular bone, which consequently prompts the occurrence of fragility fractures. We aimed to compare bone remodeling gene expression, namely Wnt/β-catenin pathway, between fragility fracture and osteoarthritis patients and to understand Wnt signaling variation in the immediate post-fracture period. In this study, we evaluated two groups of patients submitted to total hip arthroplasty either due to fragility fracture or osteoarthritis, assessed clinical data and performed gene expression and immunohistochemistry. Gene expression results showed an upregulation of osteoblast differentiation but impairment in osteoblast final maturation, together with osteoclast genes upregulation, favors bone resorption in fragility fracture patients. Regarding Wnt pathway, both groups demonstrated an increase in Wnt antagonists expression, SOST for fragility fracture patients and WIF and DKK1 (supported by immunohistochemistry results) for osteoarthritis patients. Furthermore, a decrease in Wnt inhibitors was seen during the early phase post-fracture. In fragility fracture group, osteoblastogenesis disturbances are potentiated by an increase in Wnt negative regulators and predispose these patients to fracture. Concordantly, downregulation of Wnt inhibitors may be a key step for the fracture healing process

A difficult airway approach in a merosin-deficient congenital muscular dystrophy patient: a case report

Merosin-deficient muscular dystrophy is caused by an autosomal recessive mutation on laminin-..2 gene characterized by severe progressive muscle weakness associated with neuromuscular scoliosis and restrictive lung disease. In this case report, we describe an alternative airway approach performed in a child with anticipated difficult airway and merosin-deficient muscular dystrophy. Significant anesthetic implications may increase the perioperative risk, requiring accurate knowledge to anticipate an adequate management and provide patient-safety strategies