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CNC. IBILI
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Control of glutamate release by complexes of adenosine and cannabinoid receptors
Publication . Köfalvi, Attila; Moreno, Estefanía; Cordomí, Arnau; Cai, Ning-Sheng; Fernández-Dueñas, Victor; Ferreira, Samira G.; Guixà-González, Ramón; Sánchez-Soto, Marta; Yano, Hideaki; Casadó-Anguera, Verònica; Cunha, Rodrigo A.; Sebastião, Ana M; Ciruela, Francisco; Pardo, Leonardo; Casadó, Vicent; Ferré, Sergi
Background: It has been hypothesized that heteromers of adenosine A2A receptors (A2AR) and cannabinoid CB1 receptors (CB1R) localized in glutamatergic nerve terminals mediate the integration of adenosine and endocannabinoid signaling involved in the modulation of striatal excitatory neurotransmission. Previous studies have demonstrated the existence of A2AR-CB1R heteromers in artificial cell systems. A dependence of A2AR signaling for the Gi protein-mediated CB1R signaling was described as one of its main biochemical characteristics. However, recent studies have questioned the localization of functionally significant A2AR-CB1R heteromers in striatal glutamatergic terminals.
Results: Using a peptide-interfering approach combined with biophysical and biochemical techniques in mammalian transfected cells and computational modeling, we could establish a tetrameric quaternary structure of the A2AR-CB1R heterotetramer. This quaternary structure was different to the also tetrameric structure of heteromers of A2AR with adenosine A1 receptors or dopamine D2 receptors, with different heteromeric or homomeric interfaces. The specific quaternary structure of the A2A-CB1R, which depended on intermolecular interactions involving the long C-terminus of the A2AR, determined a significant A2AR and Gs protein-mediated constitutive activation of adenylyl cyclase. Using heteromer-interfering peptides in experiments with striatal glutamatergic terminals, we could then demonstrate the presence of functionally significant A2AR-CB1R heteromers with the same biochemical characteristics of those studied in mammalian transfected cells. First, either an A2AR agonist or an A2AR antagonist allosterically counteracted Gi-mediated CB1R agonist-induced inhibition of depolarization-induced glutamate release. Second, co-application of both an A2AR agonist and an antagonist cancelled each other effects. Finally, a CB1R agonist inhibited glutamate release dependent on a constitutive activation of A2AR by a canonical Gs-Gi antagonistic interaction at the adenylyl cyclase level.
Conclusions: We demonstrate that the well-established cannabinoid-induced inhibition of striatal glutamate release can mostly be explained by a CB1R-mediated counteraction of the A2AR-mediated constitutive activation of adenylyl cyclase in the A2AR-CB1R heteromer.
Highly specific blood-brain barrier transmigrating single-domain antibodies selected by an in vivo phage display screening
Publication . Aguiar, Sandra I; Dias, Joana N. R.; André, Ana; Silva, Marta; Martins, Diana; Carrapiço, Belmira; Castanho, Miguel A. R. B.; Carrico, Joao Andre; Cavaco, Marco; Gaspar, Maria Manuela; Nobre, Rui Jorge; Pereira de Almeida, Luís; Oliveira, Soraia; Gano, Lurdes; Correia, João D. G.; Carlos F. Barbas, III; Gonçalves, João Rafael; Neves, Vera; Aires da Silva, Frederico
A major bottleneck in the successful development of central nervous system (CNS) drugs is the discovery and design of molecules that can cross the blood-brain barrier (BBB). Nano-delivery strategies are a promising approach that take advantage of natural portals of entry into the brain such as monoclonal antibodies (mAbs) targeting endogenous BBB receptors. However, the main selected mAbs rely on targeting broadly expressed receptors, such as the transferrin and insulin receptors, and in selection processes that do not fully mimic the native receptor conformation, leading to mistargeting and a low fraction of the administered dose effectively reaching the brain. Thus, there is an urgent need to identify new BBB receptors and explore novel antibody selection approaches that can allow a more selective delivery into the brain. Considering that in vitro models fail to completely mimic brain structure complexity, we explored an in vivo cell immunization approach to construct a rabbit derived single-domain antibody (sdAb) library towards BBB endothelial cell receptors. The sdAb antibody library was used in an in vivo phage display screening as a functional selection of novel BBB targeting antibodies. Following three rounds of selections, next generation sequencing analysis, in vitro brain endothelial barrier (BEB) model screenings and in vivo biodistribution studies, five potential sdAbs were identified, three of which reaching >0.6% ID/g in the brain. To validate the brain drug delivery proof-of-concept, the most promising sdAb, namely RG3, was conjugated at the surface of liposomes encapsulated with a model drug, the pan-histone deacetylase inhibitor panobinostat (PAN). The translocation efficiency and activity of the conjugate liposome was determined in a dual functional in vitro BEB-glioblastoma model. The RG3 conjugated PAN liposomes enabled an efficient BEB translocation and presented a potent antitumoral activity against LN229 glioblastoma cells without influencing BEB integrity. In conclusion, our in vivo screening approach allowed the selection of highly specific nano-antibody scaffolds with promising properties for brain targeting and drug delivery.
MPV17 mutations are associated with a quiescent energetic metabolic profile
Publication . Jacinto, Sandra; Guerreiro, Patrícia; de Oliveira, Rita Machado; Cunha-Oliveira, Teresa; Santos, Maria João; Grazina, Manuela; Rego, Ana Cristina; Outeiro, Tiago
Mutations in the MPV17 gene are associated with hepatocerebral form of mitochondrial depletion syndrome. The mechanisms through which MPV17 mutations cause respiratory chain dysfunction and mtDNA depletion is still unclear. The MPV17 gene encodes an inner membrane mitochondrial protein that was recently described to function as a non-selective channel. Although its exact function is unknown, it is thought to be important in the maintenance of mitochondrial membrane potential (ΔΨm). To obtain more information about the role of MPV17 in human disease, we investigated the effect of MPV17 knockdown and of selected known MPV17 mutations associated with MPV17 disease in vitro. We used different approaches in order to evaluate the cellular consequences of MPV17 deficiency. We found that lower levels of MPV17 were associated with impaired mitochondrial respiration and with a quiescent energetic metabolic profile. All the mutations studied destabilized the protein, resulting in reduced protein levels. We also demonstrated that different mutations caused different cellular abnormalities, including increased ROS production, decreased oxygen consumption, loss of ΔΨm, and mislocalization of MPV17 protein. Our study provides novel insight into the molecular effects of MPV17 mutations and opens novel possibilities for testing therapeutic strategies for a devastating group of disorders.
Highly specific blood-brain barrier transmigrating single-domain antibodies selected by an In Vivo phage display screening
Publication . Aguiar, Sandra Isabel; Dias, Joana N. R.; S. André, Ana; Silva, Lisete M.; Martins, Diana; Carrapiço, Belmira; Castanho, Miguel; Carriço, João; Cavaco, Marco; Aires da Silva, Frederico; [et al.]
A major bottleneck in the successful development of central nervous system (CNS) drugs
is the discovery and design of molecules that can cross the blood-brain barrier (BBB). Nano-delivery
strategies are a promising approach that take advantage of natural portals of entry into the brain
such as monoclonal antibodies (mAbs) targeting endogenous BBB receptors. However, the main
selected mAbs rely on targeting broadly expressed receptors, such as the transferrin and insulin
receptors, and in selection processes that do not fully mimic the native receptor conformation, leading
to mistargeting and a low fraction of the administered dose effectively reaching the brain. Thus, there
is an urgent need to identify new BBB receptors and explore novel antibody selection approaches that
can allow a more selective delivery into the brain. Considering that in vitro models fail to completely
mimic brain structure complexity, we explored an in vivo cell immunization approach to construct a
rabbit derived single-domain antibody (sdAb) library towards BBB endothelial cell receptors. The
sdAb antibody library was used in an in vivo phage display screening as a functional selection of
novel BBB targeting antibodies. Following three rounds of selections, next generation sequencing
analysis, in vitro brain endothelial barrier (BEB) model screenings and in vivo biodistribution studies,
five potential sdAbs were identified, three of which reaching >0.6% ID/g in the brain. To validate the
brain drug delivery proof-of-concept, the most promising sdAb, namely RG3, was conjugated at the
surface of liposomes encapsulated with a model drug, the pan-histone deacetylase inhibitor panobinostat (PAN). The translocation efficiency and activity of the conjugate liposome was determined in
a dual functional in vitro BEB-glioblastoma model. The RG3 conjugated PAN liposomes enabled an
efficient BEB translocation and presented a potent antitumoral activity against LN229 glioblastoma cells without influencing BEB integrity. In conclusion, our in vivo screening approach allowed the selection of highly specific nano-antibody scaffolds with promising properties for brain targeting and drug delivery.
A new protocol for whole-brain biodistribution analysis of AAVs by tissue clearing, light-sheet microscopy and semi-automated spatial quantification
Publication . Lopes, Miguel M.; Paysan, Jacques; Rino, José; Lopes, Sara M.; Pereira de Almeida, Luís; Cortes, Luísa; Nobre, Rui Jorge
Recombinant adeno-associated virus (rAAV) has become one of the most promising gene delivery systems for both in vitro and in vivo applications. However, a key challenge is the lack of suitable imaging technologies to evaluate delivery, biodistribution and tropism of rAAVs and efficiently monitor disease amelioration promoted by AAV-based therapies at a whole-organ level with single-cell resolution. Therefore, we aimed to establish a new pipeline for the biodistribution analysis of natural and new variants of AAVs at a whole-brain level by tissue clearing and light-sheet fluorescence microscopy (LSFM). To test this platform, neonatal C57BL/6 mice were intravenously injected with rAAV9 encoding EGFP and, after sacrifice, brains were processed by standard immunohistochemistry and a recently released aqueous-based clearing procedure. This clearing technique required no dedicated equipment and rendered highly cleared brains, while simultaneously preserving endogenous fluorescence. Moreover, three-dimensional imaging by LSFM allowed the quantitative analysis of EGFP at a whole-brain level, as well as the reconstruction of Purkinje cells for the retrieval of valuable morphological information inaccessible by standard immunohistochemistry. In conclusion, the pipeline herein described takes the AAVs to a new level when coupled to LSFM, proving its worth as a bioimaging tool in tropism and gene therapy studies.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UID/NEU/04539/2019