Albeit slowly, the implementation of EIP is spreading throughout the Italian public network of mental health. There is still a wide variability in the distribution of EIP services across the Italian territory. Further efforts are necessary to stimulate policy endorsement and resource allocation, as well as to support the poorest zones.
Peptides that translocate spontaneously across cell membranes could transform the field of drug delivery by enabling the transport of otherwise membrane-impermeant molecules into cells. In this regard, a 9-aminoacid-long motif (representative sequence: PLIYLRLLR, hereafter Translocating Motif 9, TM9) that spontaneously translocates across membranes while carrying a polar dye was recently identified by high-throughput screening. Here we investigate its transport properties by a combination of in cuvette physico-chemical assays, rational mutagenesis, live-cell confocal imaging and fluorescence correlation spectroscopy measurements. We unveil TM9 ability to self-aggregate in a concentration-dependent manner and demonstrate that peptide self-aggregation is a necessary –yet not sufficient– step for effective membrane translocation. Furthermore we show that membrane crossing can occur with apolar payloads while it is completely inhibited by polar ones. These findings are discussed and compared to previous reports. The present results impose a careful rethinking of this class of sequences as direct-translocation vectors suitable for delivery purposes.
It is widely accepted that endocytosis mediates the uptake of cationic cell penetrating peptides (CPPs) at relatively low concentrations (i.e. nano- to micromolar), while direct transduction across the plasma membrane comes into play at higher concentrations (i.e. micro- to millimolar). This latter process appears to depend on peptide-driven cellular processes, which in turn may induce local perturbations of plasma-membrane composition and/or integrity, and to be favored by peptide aggregation, especially into dimers. Besides, in most studies CPPs are tethered to fluorescent dyes in order to track peptide transduction events under the microscope, although often overlooking the possible role played by the dyes in assisting translocation. In an effort to provide some insights into the transduction process, here we report on a molecular dynamics (MD) simulation study of a prototype of the CPP family, namely the Tat arginine-rich motif. To be specific, the translocation of Tat across a purposely-created membrane pore, either or not covalently-linked to the tetramethylrhodamine-5-maleimide (TAMRA) dye and in both its monomeric and dimeric form, is analyzed in some detail. Results from several unconstrained and steered MD simulations, as well as energy decomposition analysis, nicely support the latest experimental evidence and help to shed light on key factors enabling peptide transduction. In particular, our study highlights the much slower translocation kinetics of Tat dimer in comparison to the single peptide, and therefore its enhanced capability to stabilize membrane pores. Notably, it also shows how TAMRA has overall negligible kinetic and energetic effects on peptide transduction, yet it promotes this process indirectly by favoring peptide aggregation.
By a combination of UV-Vis analyses, NMR-based diffusion measurements and MD simulations we have demonstrated for the first time that the HIV-1 Tat arginine-rich peptide (Tat) is able to self-aggregate in both its fluorescently labeled and unlabeled variants. We propose Tat dimerization as the dominant aggregation process and show that the associated equilibrium constant increases ten-fold by labeling with the standard TAMRA dye. Also, we extend similar conclusions to other cationic cell penetrating peptides (CPPs), such as Antennapedia (Ant) and nona-arginine (R9).
In this study we combined QM calculations and NMR measurements to understand at a detailed level the complex interplay of structural/electronic properties with the effects of the solvent in the NLO activity of push-pull systems, quantified in terms of variations of the static hyperpolarizability. Different parameters (bond lengths and bond length alternation, vibrational frequencies, electronic charge distribution) are introduced and tested to rationalize both the solvent sensitivity of three molecular systems (namely, p-nitroaniline, ethyl 4-ammino benzoate, and 5-nitro-1H-indole) and the differences among them. This analysis has finally allowed us to establish a clear correlation between the charge transfer behavior of the systems, their NLO properties, and NMR parameters also validating simplified but effective chemical analyses based on resonance limit forms.
Orientational order properties of two nematogens containing a fluoro- and isothiocyanate-substituted biphenyl moiety have been investigated by means of (13)C NMR spectroscopy. (13)C NMR spectra acquired on static samples under high-power (1)H-decoupling allowed both (13)C chemical shift anisotropies and (13)C-(19)F couplings to be measured. These data were used to determine the local principal order parameter and biaxiality for the different rigid fragments of the molecules. To this aim, advanced DFT methods for the calculation of geometrical parameters and chemical shift tensors were used. The orientational order parameters obtained by NMR have been critically compared with those obtained by dielectric spectroscopy. Trends of order parameters with temperature have been analyzed in terms of both mean field theory and the empirical Haller equation.
The phase behavior of a mixture of a typical insect pheromone (olean) and a phospholipid (DOPC)/water dispersion is extensively explored through SAXS, NMR and DSC experiments. The results mimic those obtained with anaesthetics in phospholipid/water systems. They also mimic the behavior and microstructure of ternary mixtures of a membrane mimetic, bilayer-forming double chained surfactants, oils and water. Taken together with recent models for conduction of the nervous impulse, all hint at lipid involvement and the underlying unity in mechanisms of pheromone, anaesthetic and hydrophobic drugs, where a local phase change in the lipid membrane architecture may be at least partly involved in the transmission of the signal.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.