Center for Innovative Biomedicine and Biotechnology

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Publications

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.

2022Journal article

Restricted access

Cx43‐mediated sorting of miRNAs into extracellular vesicles

Publication . Martins Marques, Tânia; Costa, Marina C.; Catarino, Steve; Simões, Isaura; Aasen, Trond; Enguita, Francisco J.; Girao, Henrique

Through the exchange of lipids, proteins, and nucleic acids, extracellular vesicles (EV) allow for cell-cell communication across distant cells and tissues to regulate a wide range of physiological and pathological processes. Although some molecular mediators have been discovered, the mechanisms underlying the selective sorting of miRNAs into EV remain elusive. Previous studies demonstrated that connexin43 (Cx43) forms functional channels at the EV surface, mediating the communication with recipient cells. Here, we show that Cx43 participates in the selective sorting of miRNAs into EV through a process that can also involve RNA-binding proteins. We provide evidence that Cx43 can directly bind to specific miRNAs, namely those containing stable secondary structure elements, including miR-133b. Furthermore, Cx43 facilitates the delivery of EV-miRNAs into recipient cells. Phenotypically, we show that Cx43-mediated EV-miRNAs sorting modulates autophagy. Overall, our study ascribes another biological role to Cx43, that is, the selective incorporation of miRNAs into EV, which potentially modulates multiple biological processes in target cells and may have implications for human health and disease.

2022Journal article

Restricted access

SARS-CoV-2 air and surface contamination in residential settings

Publication . Correia, Gil; Rodrigues, Luís; Afonso, Mariana; Mota, Marta; Oliveira, Joana; Soares, Rui; Tomás, Ana Luísa; Reichel, Anna; Silva, Patrícia M.; Costa, José J.; da Silva, Manuel Gameiro; Santos, Nuno C.; Gonçalves, Teresa

SARS-CoV-2 transmission occurs mainly indoors, through virus-laden airborne particles. Although the presence and infectivity of SARS-CoV-2 in aerosol are now acknowledged, the underlying circumstances for its occurrence are still under investigation. The contamination of domiciliary environments during the isolation of SARS-CoV-2-infected patients in their respective rooms in individual houses and in a nursing home was investigated by collecting surface and air samples in these environments. Surface contamination was detected in different contexts, both on high and low-touch surfaces. To determine the presence of virus particles in the air, two sampling methodologies were used: air and deposition sampling. Positive deposition samples were found in sampling locations above the patient's height, and SARS-CoV-2 RNA was detected in impactation air samples within a size fraction below 2.5 μm. Surface samples rendered the highest positivity rate and persistence for a longer period. The presence of aerosolized SARS-CoV-2 RNA occurred mainly in deposition samples and closer to symptom onset. To evaluate the infectivity of selected positive samples, SARS-CoV-2 viability assays were performed, but our study was not able to validate the virus viability. The presented results confirm the presence of aerosolized SARS-CoV-2 RNA in indoor compartments occupied by COVID-19 patients with mild symptoms, in the absence of aerosol-generating clinical procedures.

2022Journal article

Open access

Altered expression of proteins in cancer: function and potential therapeutic targets

Publication . Pessoa, João; Martins, Marta; Casimiro, Sandra; Pérez-Plasencia, Carlos; Shoshan-Barmatz, Varda

The design of innovative cancer treatments requires extensive characterization of the molecular and cellular alterations associated with tumor development and progression. Cancer cells show extensive alterations in protein expression levels, which are drivers of their malignant transformation. Proteins with altered expression levels in cancer are involved in protein synthesis and degradation, signaling and metabolic pathways, DNA repair, apoptosis, and other cellular processes, whose alterations cause tumor development and progression. Characterizing the mechanisms that lead to alterations in protein levels and their cellular effects is an invaluable tool for repurposing those proteins as drug targets. Examples of up-regulated proteins in cancer include the epidermal growth factor receptor 2 (HER2) and the vascular endothelial growth factor (VEGF). HER2 is up-regulated in several cancer types, including breast, gastroesophageal, and non-small-cell lung cancers, making it an effective drug target. VEGF is up-regulated in pancreatic, prostate, and colorectal cancers, among others. Its inhibition is also an effective anticancer treatment, through a decrease in tumor vascularization.These examples demonstrate the modulation of protein levels as an effective anticancer target, which is becoming widely used in patient treatments. These studies also encourage additional research to uncover and test novel up-/down-regulated proteins as potential new therapeutic targets.

2022Journal article

Open access

Microglia dysfunction caused by the loss of Rhoa disrupts neuronal physiology and leads to neurodegeneration

Publication . Socodato, Renato; Portugal, Camila C.; Canedo, Teresa; Rodrigues, Artur; Almeida, Tiago O.; Henriques, Joana F.; Vaz, Sandra H.; Magalhães, João; Silva, Cátia M.; Baptista, Filipa I.; Alves, Renata L.; Coelho-Santos, Vanessa; Silva, Ana Paula; Paes de Carvalho, Roberto; Magalhães, Ana; Brakebusch, Cord; Sebastião, Ana M; Summavielle, Teresa; Ambrósio, António F.; Relvas, João B.

Nervous tissue homeostasis requires the regulation of microglia activity. Using conditional gene targeting in mice, we demonstrate that genetic ablation of the small GTPase Rhoa in adult microglia is sufficient to trigger spontaneous microglia activation, producing a neurological phenotype (including synapse and neuron loss, impairment of long-term potentiation [LTP], formation of β-amyloid plaques, and memory deficits). Mechanistically, loss of Rhoa in microglia triggers Src activation and Src-mediated tumor necrosis factor (TNF) production, leading to excitotoxic glutamate secretion. Inhibiting Src in microglia Rhoa-deficient mice attenuates microglia dysregulation and the ensuing neurological phenotype. We also find that the Rhoa/Src signaling pathway is disrupted in microglia of the APP/PS1 mouse model of Alzheimer disease and that low doses of Aβ oligomers trigger microglia neurotoxic polarization through the disruption of Rhoa-to-Src signaling. Overall, our results indicate that disturbing Rho GTPase signaling in microglia can directly cause neurodegeneration.

2020Journal article

Open access