Sigma-1 receptor is a key genetic modulator in amyotrophic lateral sclerosis.

Sigma-1 receptor (S1R) is an endoplasmic reticulum (ER) chaperone that not only regulates mitochondrial respiration but also controls cellular defense against ER and oxidative stress. This makes S1R a potential therapeutic target in amyotrophic lateral sclerosis (ALS). Especially, as a missense mutation E102Q in S1R has been reported in few familial ALS cases. However, the pathogenicity of S1RE102Q and the beneficial impact of S1R in the ALS context remain to be demonstrated in vivo. To address this, we generated transgenic Drosophila that expresses human wild-type S1R or S1RE102Q. Expression of mutant S1R in fly neurons induces abnormal eye morphology and locomotor defects in a dose-dependent manner. This was accompanied by abnormal mitochondrial fragmentation, reduced adenosine triphosphate (ATP) levels and a higher fatigability at the neuromuscular junction during high energy demand. Overexpressing IP3 receptor or glucose transporter mitigates the S1RE102Q-induced eye phenotype, further highlighting the role of calcium and energy metabolism in its toxicity. More importantly, we showed that wild-type S1R rescues locomotor activity and ATP levels of flies expressing the key ALS protein, TDP43. Moreover, overexpressing wild-type S1R enhances resistance of flies to oxidative stress. Therefore, our data provide the first genetic evidence that mutant S1R recapitulates ALS pathology in vivo while increasing S1R confers neuroprotection against TDP43 toxicity.

Peptide-Based Nanoparticles to Rapidly and Efficiently "Wrap 'n Roll" siRNA into Cells.

Delivery of small interfering RNA (siRNA) as a therapeutic tool is limited due to critical obstacles such as the cellular barrier, the negative charges of the siRNA molecule, and its instability in serum. Several siRNA delivery systems have been constructed using cell-penetrating peptides (CPPs) since the CPPs have shown a high potential for oligonucleotide delivery into the cells, especially by forming nanoparticles. In this study, we have developed a new family of short (15mer or 16mer) tryptophan-(W) and arginine-(R) rich Amphipathic Peptides (WRAP) able to form stable nanoparticles and to enroll siRNA molecules into cells. The lead peptides, WRAP1 and WRAP5, form defined nanoparticles smaller than 100 nm as characterized by biophysical methods. Furthermore, they have several benefits as oligonucleotide delivery tools such as the rapid encapsulation of the siRNA, the efficient siRNA delivery in several cell types, and the high gene silencing activity, even in the presence of serum. In conclusion, we have designed a new family of CPPs specifically dedicated for siRNA delivery through nanoparticle formation. Our results indicate that the WRAP family has significant potential for the safe, efficient, and rapid delivery of siRNA for diverse applications.

Multiscale characterization of the hierarchical structure of Dynastes hercules elytra.

Beetle elytra are thickened forewings, they are lightweight and tough to protect the hindwings without hindering flight capacities. Dynastes hercules elytra are known for their hygrochromic properties. However, the whole structure of the elytron remains to be characterized. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and to our knowledge for the first time X-Ray tomography were undertaken on adult male Dynastes hercules to characterize their multi-scale structure. Trabeculae present a periodic arrangement over a short distance. Two inferred models describe the heights of plies in endocuticles of dorsal and ventral cuticles. We hypothesize that this study could provide inspiration for biomimetic materials.

A retro-inverso cell-penetrating peptide for siRNA delivery.

BACKGROUND: Small interfering RNAs (siRNAs) are powerful tools to control gene expression. However, due to their poor cellular permeability and stability, their therapeutic development requires a specific delivery system. Among them, cell-penetrating peptides (CPP) have been shown to transfer efficiently siRNA inside the cells. Recently we developed amphipathic peptides able to self-assemble with siRNAs as peptide-based nanoparticles and to transfect them into cells. However, despite the great potential of these drug delivery systems, most of them display a low resistance to proteases. RESULTS: Here, we report the development and characterization of a new CPP named RICK corresponding to the retro-inverso form of the CADY-K peptide. We show that RICK conserves the main biophysical features of its L-parental homologue and keeps the ability to associate with siRNA in stable peptide-based nanoparticles. Moreover the RICK:siRNA self-assembly prevents siRNA degradation and induces inhibition of gene expression. CONCLUSIONS: This new approach consists in a promising strategy for future in vivo application, especially for targeted anticancer treatment (e.g. knock-down of cell cycle proteins). Graphical abstract RICK-based nanoparticles: RICK peptides and siRNA self-assemble in peptide-based nanoparticles to penetrate into the cells and to induce target protein knock-down.

PEGylation rate influences peptide-based nanoparticles mediated siRNA delivery in vitro and in vivo.

Small interfering RNAs (siRNAs) present a strong therapeutic potential because of their ability to inhibit the expression of any desired protein. Recently, we developed the retro-inverso amphipathic RICK peptide as novel non-covalent siRNA carrier. This peptide is able to form nanoparticles (NPs) by self-assembling with the siRNA resulting in the fully siRNA protection based on its protease resistant peptide sequence. With regard to an in vivo application, we investigated here the influence of the polyethylene glycol (PEG) grafting to RICK NPs on their in vitro and in vivo siRNA delivery properties. A detailed structural study shows that PEGylation did not alter the NP formation (only decrease in zeta potential) regardless of the used PEGylation rates. Compared to the native RICK:siRNA NPs, low PEGylation rates (≤20%) of the NPs did not influence their cellular internalization capacity as well as their knock-down specificity (over-expressed or endogenous system) in vitro. Because the behavior of PEGylated NPs could differ in their in vivo application, we analyzed the repartition of fluorescent labeled NPs injected at the one-cell stage in zebrafish embryos as well as their pharmacokinetic (PK) profile after administration to mice. After an intra-cardiac injection of the PEGylated NPs, we could clearly determine that 20% PEG-RICK NPs reduce significantly liver and kidney accumulation. NPs with 20% PEGylation constitutes a modular, easy-to-handle drug delivery system which could be adapted to other types of functional moieties to develop safe and biocompatible delivery systems for the clinical application of RNAi-based cancer therapeutics.