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Projeto de investigação
A nanotechnology approach to Flavivirus-targeted drug development strategies
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Structural and functional properties of the capsid protein of Dengue and related Flavivirus
Publication . Faustino, André F.; Silva Martins, Ana; Karguth, Nina; Artilheiro, Vanessa; Enguita, Francisco J.; Ricardo, Joana; Santos, Nuno C.; Martins, Ivo C.
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.
A small TAT-TrkB peptide prevents BDNF receptor cleavage and restores synaptic physiology in Alzheimer's disease
Publication . Fonseca-Gomes, João; Costa-Coelho, Tiago; Ferreira-Manso, Mafalda; Inteiro-Oliveira, Sara; Vaz, Sandra H.; Alemãn-Serrano, Nuno; Atalaia Barbacena, Henrique; Ribeiro Rodrigues, Leonor; Ramalho, Rita Mira; Climaco Pinto, Rui; Vicente Miranda, Hugo; Tanqueiro, Sara; de Almeida-Borlido, Carolina; Ramalho, Maria João; Miranda-Lourenço, Catarina; Belo, Rita F.; Ferreira, Catarina B.; Neves, Vera; Rombo, Diogo M.; Viais, Ricardo; Umemori, Juzoh; Martins, Ivo C.; Jerónimo-Santos, André; Caetano, António; Manso, Nuno; Mäkinen, Petra; Marttinen, Mikael; Takalo, Mari; Bremang, Michael; Pike, Ian; Haapasalo, Annakaisa; Loureiro, Joana A.; Pereira, Maria Carmo; Santos, Nuno C.; Outeiro, Tiago; Castanho, Miguel A. R. B.; Fernandes, Adelaide; Hiltunen, Mikko; Duarte, Carlos B.; Castrén, Eero; De Mendonça, Alexandre; Sebastião, Ana M; Rodrigues, Tiago M.; Diógenes, Maria José
In Alzheimer's disease (AD), amyloid β (Aβ)-triggered cleavage of TrkB-FL impairs brain-derived neurotrophic factor (BDNF) signaling, thereby compromising neuronal survival, differentiation, and synaptic transmission and plasticity. Using cerebrospinal fluid and postmortem human brain samples, we show that TrkB-FL cleavage occurs from the early stages of the disease and increases as a function of pathology severity. To explore the therapeutic potential of this disease mechanism, we designed small TAT-fused peptides and screened their ability to prevent TrkB-FL receptor cleavage. Among these, a TAT-TrkB peptide with a lysine-lysine linker prevented TrkB-FL cleavage both in vitro and in vivo and rescued synaptic deficits induced by oligomeric Aβ in hippocampal slices. Furthermore, this TAT-TrkB peptide improved the cognitive performance, ameliorated synaptic plasticity deficits and prevented Tau pathology progression in vivo in the 5XFAD mouse model of AD. No evidence of liver or kidney toxicity was found. We provide proof-of-concept evidence for the efficacy and safety of this therapeutic strategy and anticipate that this TAT-TrkB peptide has the potential to be a disease-modifying drug that can prevent and/or reverse cognitive deficits in patients with AD.
Dengue virus capsid protein facilitates genome compaction and packaging
Publication . Boon, Priscilla L. S.; Silva Martins, Ana; Lim, Xin Ni; Enguita, Francisco J.; Santos, Nuno C.; Bond, Peter J.; Wan, Yue; Martins, Ivo C.; Huber, Roland G.
Dengue virus (DENV) is a single-stranded (+)-sense RNA virus that infects humans and mosquitoes, posing a significant health risk in tropical and subtropical regions. Mature virions are composed of an icosahedral shell of envelope (E) and membrane (M) proteins circumscribing a lipid bilayer, which in turn contains a complex of the approximately 11 kb genomic RNA with capsid (C) proteins. Whereas the structure of the envelope is clearly defined, the structure of the packaged genome in complex with C proteins remains elusive. Here, we investigated the interactions of C proteins with viral RNA, in solution and inside mature virions, via footprinting and cross-linking experiments. We demonstrated that C protein interaction with DENV genomes saturates at an RNA:C protein ratio below 1:250. Moreover, we also showed that the length of the RNA genome interaction sites varies, in a multimodal distribution, consistent with the C protein binding to each RNA site mostly in singlets or pairs (and, in some instances, higher numbers). We showed that interaction sites are preferentially sites with low base pairing, as previously measured by 2'-acetylation analyzed by primer extension (SHAPE) reactivity indicating structuredness. We found a clear association pattern emerged: RNA-C protein binding sites are strongly associated with long-range RNA-RNA interaction sites, particularly inside virions. This, in turn, explains the need for C protein in viral genome packaging: the protein has a chief role in coordinating these key interactions, promoting proper packaging of viral RNA. Such sites are, thus, highly consequential for viral assembly, and, as such, may be targeted in future drug development strategies against these and related viruses.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
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Investigador FCT
Número da atribuição
IF/00772/2013/CP1170/CT0004