Other affiliations: University of Lisbon, Nestlé, École Polytechnique Fédérale de Lausanne ...read more
Bio: Pedro Reis is an academic researcher from Instituto Superior de Agronomia. The author has contributed to research in topics: Lipase & Botrytis cinerea. The author has an hindex of 17, co-authored 34 publications receiving 2079 citations. Previous affiliations of Pedro Reis include University of Lisbon & Nestlé.
TL;DR: The presented characterization of the interfacial composition and its consequences provide a new approach for the understanding of lipase reactions at interfaces with direct impact on biotechnological and health care applications.
Abstract: Lipases are acyl hydrolases that play a key role in fat digestion by cleaving long-chain triglycerides into polar lipids Due to an opposite polarity between the enzyme (hydrophilic) and their substrates (lipophilic), lipase reaction occurs at the interface between the aqueous and the oil phases Hence, interfaces are the key spots for lipase biocatalysis and an appropriate site for modulating lipolysis Surprisingly enough, knowledge about the effects of the interfacial composition on lipase catalysis is still limited and only described by the term "interfacial quality" Recent systematic studies based on a biophysical approach allowed for the first time to show the effects of the interfacial microenvironment on lipase catalysis These studies demonstrate that lipase activity as a function of interfacial composition is more attributed to substrate inaccessibility rather than to enzyme denaturation or inactivation, as it is often hypothesized A detailed analysis of the interfacial properties of all compounds involved in triglyceride digestion revealed that lipolysis is a self-regulated reaction This feedback mechanism can be explored as a new avenue to control lipase catalysis To substantiate this hypothesis, oil hydrolysis in a model gastro-intestinal system was performed, which can be seen as an interfacial engineering approach to enzyme reactivity control The presented characterization of the interfacial composition and its consequences provide a new approach for the understanding of lipase reactions at interfaces with direct impact on biotechnological and health care applications
TL;DR: Conservation among members of the ICE/CED-3 family of the amino acids that form the active site region of ICE supports the hypothesis that they share functional similarities.
Abstract: Interleukin-1β-converting enzyme (ICE) proteolytically cleaves pro-IL-1β to its mature, active form. The crystal structure at 2.5 A resolution of a recombinant human ICE-tetrapeptide chloromethylketone complex reveals that the holoenzyme is a homodimer of catalytic domains, each of which contains a p20 and a p10 subunit. The spatial separation of the C-terminus of p20 and the N-terminus of p10 in each domain suggests two alternative pathways of assembly and activation in vivo. ICE is homologous to the C. elegans cell death gene product, CED-3, and these may represent a novel class of cytoplasmic cysteine proteases that are important in programmed cell death (apoptosis). Conservation among members of the ICE/CED-3 family of the amino acids that form the active site region of ICE supports the hypothesis that they share functional similarities.
TL;DR: The data corroborate the hypothesis that liposomes carrying phosphorylated peptides of protein Tau have considerable potential as safe and effective treatment against tauopathies, including Alzheimer's disease.
Abstract: Progressive aggregation of protein Tau into oligomers and fibrils correlates with cognitive decline and synaptic dysfunction, leading to neurodegeneration in vulnerable brain regions in Alzheimer's disease. The unmet need of effective therapy for Alzheimer's disease, combined with problematic pharmacological approaches, led the field to explore immunotherapy, first against amyloid peptides and recently against protein Tau. Here we adapted the liposome-based amyloid vaccine that proved safe and efficacious, and incorporated a synthetic phosphorylated peptide to mimic the important phospho-epitope of protein Tau at residues pS396/pS404. We demonstrate that the liposome-based vaccine elicited, rapidly and robustly, specific antisera in wild-type mice and in Tau.P301L mice. Long-term vaccination proved to be safe, because it improved the clinical condition and reduced indices of tauopathy in the brain of the Tau.P301L mice, while no signs of neuro-inflammation or other adverse neurological effects were observed. The data corroborate the hypothesis that liposomes carrying phosphorylated peptides of protein Tau have considerable potential as safe and effective treatment against tauopathies, including Alzheimer's disease.
TL;DR: From the mathematical modeling of the interface composition, it is concluded that Sn-2 monopalmitin can desorb lipase from the interface, which explains the gradually decreased triglyceride hydrolysis that occurs during the digestion.
Abstract: In the present study, we use a model gastro-intestinal system to study the influence of different food-grade surface-active molecules (Sn-2 monopalmitin, β-lactoglobulin, or lysophosphatodylcholine) on lipase activity. The interfacial activity of lipase and surfactants are assessed with the pendant drop technique, a commonly used tensiometry instrument. A mathematical model is adopted which enables quantitative determination of the composition of the water–oil interface as a function of bulk surfactant concentration in the water–oil mixtures. Our results show a decrease in gastric lipolysis when interfacially active molecules are incorporated into a food matrix. However, only the Sn-2 monopalmitin caused a systematic decrease in triglyceride hydrolysis throughout the gastro-intestinal tract. This effect is most likely due to exclusion of both lipase and triglyceride from the water–oil interface together with a probable saturation of the solubilization capacity of bile with monoglycerides. Addition of β-lactoglobulin or lysophopholipids increased the hydrolysis of fat after the gastric phase. These results can be attributed to an increasing interfacial area with lipase and substrate present at the interface. Otherwise, β-lactoglobulin, or lysophopholipids reduced fat hydrolysis in the stomach. From the mathematical modeling of the interface composition, we can conclude that Sn-2 monopalmitin can desorb lipase from the interface, which, together with exclusion of substrate from the interface, explains the gradually decreased triglyceride hydrolysis that occurs during the digestion. Our results provide a biophysics approach on lipolysis that can bring new insights into the problem of fat uptake.
TL;DR: The results obtained can be transferred to the in vivo situation and the formation of stable and amphiphilic Sn-2 monoglycerides can be seen as a self-regulatory process for fat digestion.
Abstract: Tensiometry (the pendant drop technique), interfacial shear rheology, and ellipsometry have been used to study the effect of polar lipids that are generated during fat digestion on the behavior of lipases at the oil−water interface. Both Sn-1,3 regiospecific and nonregiospecific lipases have been used, and a noncatalytically active protein, β-lacloglobulin, has been used as reference in the interfacial shear rheology experiments. The results from the pendant drop measurements and the interfacial rheology studies were in agreement with each other and demonstrated that the Sn-2 monoglyceride, which is one of the lipolysis products generated when a Sn-1,3 regiospecific lipase catalyzes triglyceride hydrolysis, is very interfacially active and efficiently expels the enzyme from the interface. Ellipsometry conducted at the liquid−liquid interface showed that the lipase forms a sublayer in the aqueous phase, just beneath the monoglyceride-covered interface. Sn-1/3 monoglycerides do not behave this way because t...
TL;DR: The basic components of the death machinery are reviewed, how they interact to regulate apoptosis in a coordinated manner is described, and the main pathways that are used to activate cell death are discussed.
Abstract: Apoptosis - the regulated destruction of a cell - is a complicated process. The decision to die cannot be taken lightly, and the activity of many genes influence a cell's likelihood of activating its self-destruction programme. Once the decision is taken, proper execution of the apoptotic programme requires the coordinated activation and execution of multiple subprogrammes. Here I review the basic components of the death machinery, describe how they interact to regulate apoptosis in a coordinated manner, and discuss the main pathways that are used to activate cell death.
TL;DR: This work has shown that understanding caspase regulation is intimately linked to the ability to rationally manipulate apoptosis for therapeutic gain.
Abstract: Apoptosis, an evolutionarily conserved form of cell suicide, requires specialized machinery. The central component of this machinery is a proteolytic system involving a family of proteases called caspases. These enzymes participate in a cascade that is triggered in response to proapoptotic signals and culminates in cleavage of a set of proteins, resulting in disassembly of the cell. Understanding caspase regulation is intimately linked to the ability to rationally manipulate apoptosis for therapeutic gain.
TL;DR: The importance of caspase prodomains in the regulation of apoptosis is further highlighted by the recognition of adapter molecules, such as RAIDD [receptor-interacting protein (RIP)-associated ICH-1/CED-3-homologous protein with a death domain]/CRADD (caspase and RIP adapter with death domain), which binds to the prodomain of cspase-2 and recruits it to the signalling complex.
Abstract: Apoptosis is a major form of cell death, characterized initially by a series of stereotypic morphological changes. In the nematode Caenorhabditis elegans, the gene ced-3 encodes a protein required for developmental cell death. Since the recognition that CED-3 has sequence identity with the mammalian cysteine protease interleukin-1 beta-converting enzyme (ICE), a family of at least 10 related cysteine proteases has been identified. These proteins are characterized by almost absolute specificity for aspartic acid in the P1 position. All the caspases (ICE-like proteases) contain a conserved QACXG (where X is R, Q or G) pentapeptide active-site motif. Capases are synthesized as inactive proenzymes comprising an N-terminal peptide (prodomain) together with one large and one small subunit. The crystal structures of both caspase-1 and caspase-3 show that the active enzyme is a heterotetramer, containing two small and two large subunits. Activation of caspases during apoptosis results in the cleavage of critical cellular substrates, including poly(ADP-ribose) polymerase and lamins, so precipitating the dramatic morphological changes of apoptosis. Apoptosis induced by CD95 (Fas/APO-1) and tumour necrosis factor activates caspase-8 (MACH/FLICE/Mch5), which contains an N-terminus with FADD (Fas-associating protein with death domain)-like death effector domains, so providing a direct link between cell death receptors and the caspases. The importance of caspase prodomains in the regulation of apoptosis is further highlighted by the recognition of adapter molecules, such as RAIDD [receptor-interacting protein (RIP)-associated ICH-1/CED-3-homologous protein with a death domain]/CRADD (caspase and RIP adapter with death domain), which binds to the prodomain of caspase-2 and recruits it to the signalling complex. Cells undergoing apoptosis following triggering of death receptors execute the death programme by activating a hierarchy of caspases, with caspase-8 and possibly caspase-10 being at or near the apex of this apoptotic cascade.
TL;DR: This is a lengthy review, with 586 citations chosen to illustrate specific areas of interest rather than a compendium of references, which summarizes what the author considers established or controversial topics linking the biology of IL-1 to mechanisms of disease.
Abstract: To understand the role of the proinflammatory cytokine interleukin-1 (IL-1) in disease, investigators have studied how production of the different members of the IL-1 family is controlled, the various biologic activities of IL-1, the distinct and various functions of the IL-1 receptor (IL-1R) family, and the complexity of intracellular signaling. Mice deficient in IL-1Beta, IL-1Beta converting enzyme, and IL-1R type I have also been studied. Humans have been injected with IL-1 (either IL-1alpha or IL-1beta) for enhancing bone marrow recovery and for cancer treatment. The IL-1-specific receptor antagonist (IL-1Ra) has also been tested in clinical trials. The topics discussed in this review include production and activities of IL-1 and IL-1Ra molecules, the effects of IL-1 on gene expression, functions of cell-bound and soluble IL-1 receptors, the importance of the IL-1R accessory protein, newly discovered signal transduction pathways, naturally occurring cytokines limiting IL-1 production or activity, the effects of blocking cyclooxygenase and nitric oxide, and the outcomes of IL-1 and IL-1 Ra in human trials. Special attention is paid to IL-1beta converting enzyme and programmed cell death. The roles of IL-1 in hematopoiesis, leukemia, atherosclerosis, and growth of solid tumors are also discussed. This is a lengthy review, with 586 citations chosen to illustrate specific areas of interest rather than a compendium of references. At the end of each section, a short commentary summarizes what the author considers established or controversial topics linking the biology of IL-1 to mechanisms of disease.
TL;DR: A potent peptide aldehyde inhibitor has been developed and shown to prevent apoptotic events in vitro, suggesting that apopain/CPP32 is important for the initiation of apoptotic cell death.
Abstract: The protease responsible for the cleavage of poly(ADP-ribose) polymerase and necessary for apoptosis has been purified and characterized. This enzyme, named apopain, is composed of two subunits of relative molecular mass (M(r)) 17K and 12K that are derived from a common proenzyme identified as CPP32. This proenzyme is related to interleukin-1 beta-converting enzyme (ICE) and CED-3, the product of a gene required for programmed cell death in Caenorhabditis elegans. A potent peptide aldehyde inhibitor has been developed and shown to prevent apoptotic events in vitro, suggesting that apopain/CPP32 is important for the initiation of apoptotic cell death.