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Peptides that signal hunger – a new role in memory and social behaviors
Publication . Carvalho, Mário Jorge da Silva; Silvestre, João; Carvalho, Ana; Ponte, Manuel
Neuroactive peptides and their receptors in neurons are a large group of molecules essential for central nervous system homeostasis. They participate in the control of basic functions, such as regulation of the cardiovascular system and gastrointestinal tract, and in higher function, such as cognition and social behavior. In this work we provide an overview of common features of these signaling molecules, their receptors and explore how they regulate two important behaviors: memory and social behaviors. We describe the role of the constitutive activity of the ghrelin receptor on learning and memory and explore a mechanism for its effect on neuronal transmission. Through pharmacologic manipulation, we observed that the ligand-independent activity of the ghrelin receptor regulates the surface and synaptic expression of AMPA receptors on neurons. This effect is exerted through the regulation of AMPA receptor mobility and phosphorylation state. On another section of the work, we describe alterations to the prefrontal cortex in a model of early life stress. We find that social subordinate behavior is induced by stress and explore the mechanism leading to this behavioral alteration. We find increased inhibition in pyramidal neurons of the prefrontal cortex in subordinate animals accompanied by increased expression of the Y1 receptor for neuropeptide Y. Using whole-cell patch-clamp recordings, we observed a reversion of the increased inhibition in the prefrontal cortex of subordinate animals when using an NPY Y1 antagonist. In addition to its well-known role in feeding behavior, our observations suggest that the neuropeptide Y signaling plays a role in the processing of social behaviors in the mammalian brains. This work illustrates the versatility of neuroactive peptides in the regulation of animal behavior. We provide potential avenues for the development of treatments for diseases associated with cognitive deficits and dysfunctional subordinate behavior.
Modulation of the haematopoietic stem cell niche by photo-triggerable nanoparticles
Publication . Costa, Emanuel Nery de Oliveira Quartin; Neves, Ricardo; Ferreira, Lino; Ponte, Manuel
The bone-marrow haematopoietic stem cell niche is a protective hard to reach microenvironment that is difficult to modulate in the context of HSC transplant and malignant haematopoietic disease. In this thesis we developed new strategies to tackle this by the use of a combination of nanomedicine tools and cell-mediated delivery systems. In the context of leukaemia, cells that are resistant to conventional therapies are thought to reside in protective niches. Here, we describe light-inducible polymeric retinoic acid (RA)-containing nanoparticles (NPs) with the capacity to accumulate in the cytoplasm of leukaemia cells for several days and release their RA payloads within a few minutes upon exposure to blue/UV light. Compared to NPs that are not activated by light exposure, these NPs more efficiently reduce the clonogenicity of bone marrow cancer cells from patients with AML and induce the differentiation of RA-low sensitive leukaemia cells. Importantly, we show that leukaemia cells transfected with light-inducible NPs containing RA can engraft into bone marrow in vivo in the proximity of other leukaemic cells, differentiate upon exposure to blue light and release paracrine factors that modulate nearby cells. This capacity of remotely modulating the leukaemic niche has been tested in an AML disease animal model with success. RA+NPs induced AML differentiation towards monocytic/macrophage lineage in the MLL-AF9 mouse model of AML. Also, we have shown in vitro that RA+NPs stimulate antitumoral M1 macrophage activation. This macrophage induced differentiation in vivo seems to have “systemic” anti-leukemic effect within the BM leukemic niche, as we observed a significant reduction of leukemic cells in the BM of animals treated with RA+NPs when compared with animals treated with empty NPs (RA-NPs). Finally, prospective studies on the use of healthy HSCs as carriers have shown that despite having a more sensitive behaviour UCB CD34+cells can be loaded with RA+NP and after light-activated release of RA, induce CD38 expression and differentiate. Towards the use of this type of tools in the context of HSC transplant engraftment modulation we were able to produce functional HOXB4, a pivotal transcription factor for HSC potency, that was able to induce G0 quiescence, but NP-functionalization with this molecule remains a challenge and is the subject of future work.
Comparative proteomic analysis of nodulated and non-nodulated casuarina glauca sieb. Ex spreng. grown under salinity conditions using sequential window acquisition of all theoretical mass spectra (SWATH-MS)
Publication . Graça, Inês; Mendes, Vera M.; Marques, Isabel; Duro, Nuno; da Costa, Mário; Ramalho, José C.; Pawlowski, Katharina; Manadas, Bruno; Pinto Ricardo, Cândido P.; Ribeiro-Barros, Ana Isabel; Instituto de Tecnologia Química e Biológica António Xavier (ITQB); GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; MDPI - Multidisciplinary Digital Publishing Institute
Casuarina glauca displays high levels of salt tolerance, but very little is known about how this tree adapts to saline conditions. To understand the molecular basis of C. glauca response to salt stress, we have analyzed the proteome from branchlets of plants nodulated by nitrogen-fixing Frankia Thr bacteria (NOD+) and non-nodulated plants supplied with KNO3 (KNO3+), exposed to 0, 200, 400, and 600 mM NaCl. Proteins were identified by Short Gel, Long Gradient Liquid Chromatography coupled to Tandem Mass Spectrometry and quantified by Sequential Window Acquisition of All Theoretical Mass Spectra -Mass Spectrometry. 600 proteins were identified and 357 quantified. Differentially Expressed Proteins (DEPs) were multifunctional and mainly involved in Carbohydrate Metabolism, Cellular Processes, and Environmental Information Processing. The number of DEPs increased gradually with stress severity: (i) from 7 (200 mM NaCl) to 40 (600 mM NaCl) in KNO3+; and (ii) from 6 (200 mM NaCl) to 23 (600 mM NaCl) in NOD+. Protein–protein interaction analysis identified different interacting proteins involved in general metabolic pathways as well as in the biosynthesis of secondary metabolites with different response networks related to salt stress. Salt tolerance in C. glauca is related to a moderate impact on the photosynthetic machinery (one of the first and most important stress targets) as well as to an enhancement of the antioxidant status that maintains cellular homeostasis.
Osmotic modulation of chromatin impacts on efficiency and kinetics of cell fate modulation
Publication . Lima, A. F.; May, G.; Colunga, J.; Pedreiro, S.; Paiva, A.; Ferreira, L.; Enver, T.; Iborra, F. J.; Pires Das Neves, R.; Faculdade de Ciências e Tecnologia (FCT); Nature Publishing Group
Chromatin structure is a major regulator of transcription and gene expression. Herein we explore the use of osmotic modulation to modify the chromatin structure and reprogram gene expression. In this study we use the extracellular osmotic pressure as a chromatin structure and transcriptional modulator. Hyposmotic modulation promotes chromatin loosening and induces changes in RNA polymerase II (Pol II) activity. The chromatin decondensation opens space for higher amounts of DNA engaged RNA Pol II. Hyposmotic modulation constitutes an alternative route to manipulate cell fate decisions. This technology was tested in model protocols of induced pluripotency and transdifferentiation in cells growing in suspension and adherent to substrates, CD34 + umbilical-cord-blood (UCB), fibroblasts and B-cells. The efficiency and kinetics of these cell fate modulation processes were improved by transient hyposmotic modulation of the cell environment.
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
5876
Número da atribuição
UID/NEU/04539/2013