Time filter

Source Type

Martins A.P.,Research Institute For Medicines And Pharmaceutical Science Imedul | Martins A.P.,University of Lisbon | Ciancetta A.,University of Padua | deAlmeida A.,University of Groningen | And 5 more authors.

Aquaporins (AQPs) are membrane water/glycerol channels with essential roles in biological systems, as well as being promising targets for therapy and imaging. Using a stopped-flow method, a series of gold(III), platinum(II) and copper(II) complexes bearing nitrogen donor ligands, such as 1,10-phenatroline, 2,2′-bipyridine, 4,4′-dimethyl-2,2′-bipyridine, 4,4′-diamino-2,2′-bipyridine and 2,2′;6′,2"-terpyridine, were evaluated in human red blood cells expressing AQP1 and AQP3, responsible for water and glycerol movement, respectively. The results showed that the gold(III) complexes selectively modulate AQP3 over AQP1. Molecular modeling and density functional theory (DFT) calculations were subsequently performed to rationalize the observations and to investigate the possible molecular mechanism through which these gold compounds act on their putative target (AQP3). In the absence of any crystallographic data, a previously reported homology model was used for this purpose. Combined, the findings of this study show that potent and selective modulation of these solute channels is possible, however further investigation is required into the selectivity of this class of agents against all AQP isoforms and their potential therapeutic uses. Clogging up the plumbing: Aquaglyceroporin-3 (AQP3) inhibition by gold(III) compounds with nitrogen donor ligands was demonstrated in human red blood cells. Computational studies provided insight into the possible molecular mechanism and binding mode to their putative target (AQP3). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Aires C.C.P.,Research Institute For Medicines And Pharmaceutical Science Imedul | Aires C.C.P.,Metabolic | IJlst L.,Metabolic | Stet F.,Metabolic | And 5 more authors.
Biochemical Pharmacology

Background/Aims: Carnitine palmitoyl-transferase I (CPT I) catalyses the synthesis of long-chain (LC)-acylcarnitines from LC-acyl-CoA esters. It is the rate-limiting enzyme of mitochondrial fatty acid β-oxidation (FAO) pathway and its activity is regulated by malonyl-CoA. The antiepileptic drug valproic acid (VPA) is a branched chain fatty acid that is activated to the respective CoA ester in the intra- and extra-mitochondrial compartments. This drug has been associated with a clear inhibition of mitochondrial FAO, which motivated our study on its potential effect on hepatic CPT I. Methods: To investigate the effect of valproyl-CoA (VP-CoA) on CPT I, we performed in vitro studies using control human fibroblasts and rat CPT IA expressed in Saccharomyces cerevisiae. In addition to the wild-type enzyme, two mutant rCPT IAs were studied, one of which showing increased sensitivity towards malonyl-CoA (S24A/Q30A), whereas the other one is insensitive to malonyl-CoA (E3A). Results: We demonstrate that VP-CoA inhibits the CPT I activity in control fibroblasts. Similar results were obtained using rCPT IA WT and S24A/Q30A. Importantly, VP-CoA also inhibited the activity of the rCPT IA E3A. We show that VP-CoA inhibits CPT IA competitively with respect to palmitoyl-CoA, and non-competitively to carnitine. Evidence is provided that VP-CoA interferes at the catalytic domain of CPT IA affecting the sensitivity for malonyl-CoA. Conclusions: The interference of VP-CoA with CPT IA, a pivotal enzyme in mitochondrial fatty acid β-oxidation, may be a crucial mechanism in the drug-induced hepatotoxicity and the weight gain frequently observed in patients under VPA therapy. © 2009 Elsevier Inc. All rights reserved. Source

Sola S.,Research Institute For Medicines And Pharmaceutical Science Imedul | Sola S.,University of Lisbon | Morgado A.L.,Research Institute For Medicines And Pharmaceutical Science Imedul | Rodrigues C.M.P.,Research Institute For Medicines And Pharmaceutical Science Imedul | Rodrigues C.M.P.,University of Lisbon
Biochimica et Biophysica Acta - General Subjects

Background: Stem cell therapy is a strategy far from being satisfactory and applied in the clinic. Poor survival and differentiation levels of stem cells after transplantation or neural injury have been major problems. Recently, it has been recognized that cell death-relevant proteins, notably those that operate in the core of the executioner apoptosis machinery are functionally involved in differentiation of a wide range of cell types, including neural cells. Scope of review: This article will review recent studies on the mechanisms underlying the non-apoptotic function of mitochondrial and death receptor signaling pathways during neural differentiation. In addition, we will discuss how these major apoptosis-regulatory pathways control the decision between differentiation, self-renewal and cell death in neural stem cells and how levels of activity are restrained to prevent cell loss as final outcome. Major conclusions: Emerging evidence suggests that, much like p53, caspases and Bcl-2 family members, the two prime triggers of cell death pathways, death receptors and mitochondria, may influence proliferation and differentiation potential of stem cells, neuronal plasticity, and astrocytic versus neuronal stem cell fate decision. General significance: A better understanding of the molecular mechanisms underlying key checkpoints responsible for neural differentiation as an alternative to cell death will surely contribute to improve neuro-replacement strategies. © 2012 Elsevier B.V. © 2012 Elsevier B.V. All rights reserved. Source

Ferreira R.J.,Research Institute For Medicines And Pharmaceutical Science Imedul | Ferreira M.-J.U.,Research Institute For Medicines And Pharmaceutical Science Imedul | Dos Santos D.J.V.A.,Research Institute For Medicines And Pharmaceutical Science Imedul | Dos Santos D.J.V.A.,University of Porto
Molecular Informatics

This paper focuses on the importance of the intermediate linker sequence for the stabilization of the cytoplasmic portion of murine P-glycoprotein, an ABC transporter involved in Multidrug Resistance (MDR) in cancer. Three putative protein-protein interaction areas were predicted to exist, two of them next to the C-terminal nucleotide-binding domain (NBD2) and the third one next to the inner leaflet interface of the lipid bilayer. These contact spots were confirmed by detailed contact maps from structures obtained before and after a 100 ns molecular dynamics production run, allowing a more thorough characterization of the type and number of residues involved in protein-protein contacts. It was found that these contact surfaces are located next to several highly conserved motifs of ABC transporters, serving as anchor points and assisting the linker's 'damper' function. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Pinheiro A.,Research Institute For Medicines And Pharmaceutical Science Imedul | Nunes M.J.,Research Institute For Medicines And Pharmaceutical Science Imedul | Milagre I.,Research Institute For Medicines And Pharmaceutical Science Imedul | Rodrigues E.,Research Institute For Medicines And Pharmaceutical Science Imedul | And 7 more authors.

Human PDHA2 is a testis-specific gene that codes for the E1α subunit of Pyruvate Dehydrogenase Complex (PDC), a crucial enzyme system in cell energy metabolism. Since activation of the PDHA2 gene in somatic cells could be a new therapeutic approach for PDC deficiency, we aimed to identify the regulatory mechanisms underlying the human PDHA2 gene expression. Functional deletion studies revealed that the -122 to -6 promoter region is indispensable for basal expression of this TATA-less promoter, and suggested a role of an epigenetic program in the control of PDHA2 gene expression. Indeed, treatment of SH-SY5Y cells with the hypomethylating agent 5-Aza-2′-deoxycytidine (DAC) promoted the reactivation of the PDHA2 gene, by inducing the recruitment of the RNA polymerase II to the proximal promoter region and the consequent increase in PDHA2 mRNA levels. Bisulfite sequencing analysis revealed that DAC treatment induced a significant demethylation of the CpG island II (nucleotides +197 to +460) in PDHA2 coding region, while the promoter region remained highly methylated. Taken together with our previous results that show an in vivo correlation between PDHA2 expression and the demethylation of the CpG island II in testis germ cells, the present results show that internal methylation of the PDHA2 gene plays a part in its repression in somatic cells. In conclusion, our data support the novel finding that methylation of the PDHA2 coding region can inhibit gene transcription. This represents a key mechanism for absence of PDHA2 expression in somatic cells and a target for PDC therapy. © 2012 Pinheiro et al. Source

Discover hidden collaborations