CD95L concatemers highlight different stoichiometries of CD95-mediated apoptotic and nonapoptotic pathways.

To better understand the stoichiometry of CD95L required to trigger apoptotic and nonapoptotic signals, we generated several CD95L concatemers from dimer to hexamer conjugated via a flexible link (GGGGS)2 . These ligands reveal that although the hexameric structure is the best stoichiometry to trigger cell death, a dimer is sufficient to induce the apoptotic response in CD95-sensitive Jurkat cells. Interestingly, only trimeric and hexameric forms can implement a potent Ca2+ response, suggesting that while CD95 aggregation controls the implementation of the apoptotic signal, both aggregation and conformation are required to implement the Ca2+ pathway.

Identification of the master sex determining gene in Northern pike (Esox lucius) reveals restricted sex chromosome differentiation.

Teleost fishes, thanks to their rapid evolution of sex determination mechanisms, provide remarkable opportunities to study the formation of sex chromosomes and the mechanisms driving the birth of new master sex determining (MSD) genes. However, the evolutionary interplay between the sex chromosomes and the MSD genes they harbor is rather unexplored. We characterized a male-specific duplicate of the anti-Müllerian hormone (amh) as the MSD gene in Northern Pike (Esox lucius), using genomic and expression evidence as well as by loss-of-function and gain-of-function experiments. Using RAD-Sequencing from a family panel, we identified Linkage Group (LG) 24 as the sex chromosome and positioned the sex locus in its sub-telomeric region. Furthermore, we demonstrated that this MSD originated from an ancient duplication of the autosomal amh gene, which was subsequently translocated to LG24. Using sex-specific pooled genome sequencing and a new male genome sequence assembled using Nanopore long reads, we also characterized the differentiation of the X and Y chromosomes, revealing a small male-specific insertion containing the MSD gene and a limited region with reduced recombination. Our study reveals an unexpectedly low level of differentiation between a pair of sex chromosomes harboring an old MSD gene in a wild teleost fish population, and highlights both the pivotal role of genes from the amh pathway in sex determination, as well as the importance of gene duplication as a mechanism driving the turnover of sex chromosomes in this clade.

Disrupting the CD95-PLCγ1 interaction prevents Th17-driven inflammation.

CD95L is a transmembrane ligand (m-CD95L) that is cleaved by metalloproteases to release a soluble ligand (s-CD95L). Unlike m-CD95L, interaction between s-CD95L and CD95 fails to recruit caspase-8 and FADD to trigger apoptosis and instead induces a Ca2+ response via docking of PLCγ1 to the calcium-inducing domain (CID) within CD95. This signaling pathway induces accumulation of inflammatory Th17 cells in damaged organs of lupus patients, thereby aggravating disease pathology. A large-scale screen revealed that the HIV protease inhibitor ritonavir is a potent disruptor of the CD95-PLCγ1 interaction. A structure-activity relationship approach highlighted that ritonavir is a peptidomimetic that shares structural characteristics with CID with respect to docking to PLCγ1. Thus, we synthesized CID peptidomimetics abrogating both the CD95-driven Ca2+ response and transmigration of Th17 cells. Injection of ritonavir and the CID peptidomimetic into lupus mice alleviated clinical symptoms, opening a new avenue for the generation of drugs for lupus patients.

Probing the side chain tolerance for inhibitors of the CD95/PLCγ1 interaction.

Proceeding our effort to study protein-protein interaction between the death receptor CD95 and phospholipase PLCγ1, we present in the current work chameleon-like traits of peptidomimetic inhibitors. Minute analysis of the interaction suggests that most of the binding energy relies on van der Waals contacts rather than more specific features, such as hydrogen bonds or salt bridges. The two most important positions of the peptoid for its interaction with PLCγ1 (Arg184 and Arg187) were modified to test this hypothesis. While Arg184 proves to be exchangeable for Trp, with no alteration in affinity, the nature of the amino acid replacing Arg187 is more dependent on its positive charge. However, affinity can be partially recovered by increasing van der Waals interactions. Overall, this study shows that for both positions, a subtle balance exists between hydrophobicity, surface contacts and affinity for CD95/PLCγ1, and provides information for the generation of new therapeutic compounds toward this druggable target.

Synthesis of peptidomimetics and chemo-biological tools for CD95/PLCγ1 interaction analysis.

The death receptor CD95 (also known as Fas) induces apoptosis through protein/protein association and the formation of the death-inducing signaling complex. On the other hand, in certain biological conditions, this receptor recruits different proteins and triggers the formation of another complex designated motility-inducing signaling complex, which promotes cell migration and inflammation. This pathway relies on a short sequence of CD95, called calcium-inducing domain (CID), which interacts with the phospholipase PLCγ1. To better understand how CID/PLCγ1 interaction occurs, we synthesized different α-AA peptides mimicking CID. Some of these peptidomimetics are as potent as the natural peptide to disrupt the CID/PLCγ1 interaction and cell migration, and showed improved pharmacokinetic properties. We also generated biotinyl- and palmitoyl-labelled peptidomimetics, useful chemico-biological tools to further explore the pro-inflammatory signal of CD95, which plays an important role in the pathogenesis of lupus and other autoimmune diseases.

Synthesis and evaluation of 1,3,4-oxadiazole derivatives for development as broad-spectrum antibiotics.

The reality and intensity of antibiotic resistance in pathogenic bacteria calls for the rapid development of new antimicrobial drugs. In bacteria, trans-translation is the primary quality control mechanism for rescuing ribosomes arrested during translation. Because trans-translation is absent in eukaryotes but necessary to avoid ribosomal stalling and therefore essential for bacterial survival, it is a promising target either for novel antibiotics or for improving the activities of the protein synthesis inhibitors already in use. Oxadiazole derivatives display strong bactericidal activity against a large number of bacteria, but their effects on trans-translation were recently questioned. In this work, a series of new 1,3,4-oxadiazole derivatives and analogs were synthesized and assessed for their efficiency as antimicrobial agents against a wide range of gram-positive and gram-negative pathogenic strains. Despite the strong antimicrobial activity observed in these molecules, it turns out that they do not target trans-translation in vivo, but they definitely act on other cellular pathways.

Investigation of Phospholipase Cγ1 Interaction with SLP76 Using Molecular Modeling Methods for Identifying Novel Inhibitors.

The enzyme phospholipase C gamma 1 (PLCγ1) has been identified as a potential drug target of interest for various pathological conditions such as immune disorders, systemic lupus erythematosus, and cancers. Targeting its SH3 domain has been recognized as an efficient pharmacological approach for drug discovery against PLCγ1. Therefore, for the first time, a combination of various biophysical methods has been employed to shed light on the atomistic interactions between PLCγ1 and its known binding partners. Indeed, molecular modeling of PLCγ1 with SLP76 peptide and with previously reported inhibitors (ritonavir, anethole, daunorubicin, diflunisal, and rosiglitazone) facilitated the identification of the common critical residues (Gln805, Arg806, Asp808, Glu809, Asp825, Gly827, and Trp828) as well as the quantification of their interaction through binding energies calculations. These features are in agreement with previous experimental data. Such an in depth biophysical analysis of each complex provides an opportunity to identify new inhibitors through pharmacophore mapping, molecular docking and MD simulations. From such a systematic procedure, a total of seven compounds emerged as promising inhibitors, all characterized by a strong binding with PLCγ1 and a comparable or higher binding affinity to ritonavir (∆Gbind < -25 kcal/mol), one of the most potent inhibitor reported till now.

Modular Synthesis of Arylacetic Acid Esters, Thioesters, and Amides from Aryl Ethers via Rh(II)-Catalyzed Diazo Arylation.

One-pot formation of arylacetic acid esters, thioesters, and amides via Rh(II)-catalyzed arylation of a Meldrum's acid-derived diazo reagent with electron-rich arenes is described. The methodology was used to efficiently synthesize an anticancer compound.

Synthesis of stachybotrin C and all of its stereoisomers: structure revision.

We disclose the first total synthesis of stachybotrin C, a potent neuroprotective natural compound. All of the four stereoisomers have been prepared and fully characterized with the aim to attribute the absolute configuration of the two adjacent stereocenters of the stachybotrin C.

CD95 (Fas) and CD95L (FasL)-mediated non-canonical signaling pathways.

Although the interaction of CD95L (also known as FasL) with its so-called death receptor CD95 (Fas) induces an apoptotic signal responsible for the elimination of infected and cancer cells and maintenance of tissue homeostasis, this receptor can also implement non apoptotic signaling pathways. This latter signaling is involved in metastatic dissemination in certain cancers and the severity of auto-immune disorders. The signaling complexity of this pair is increased by the fact that CD95 expression itself seems to contribute to oncogenesis via a CD95L-independent manner and, that both ligand and receptor might interact with other partners modulating their pathophysiological functions. Finally, CD95L itself can trigger cell signaling in immune cells rendering complex the interpretation of mouse models in which CD95 or CD95L are knocked out. Herein, we discuss these non-canonical responses and their biological functions.

When the nine-membered enediynes play hide and seek.

The lack of stability of the 9-membered enediynes not associated with an apoprotein may explain the low number of isolated natural compounds containing this core. To overcome such a problem, particular attention should be paid during the process of extraction and isolation of secondary metabolites, especially from microorganisms such as actinomycetes in order to identify the non-cycloaromatized derivatives.

Role of metalloproteases in the CD95 signaling pathways.

CD95L (also known as FasL or CD178) is a member of the tumor necrosis family (TNF) superfamily. Although this transmembrane ligand has been mainly considered as a potent apoptotic inducer in CD95 (Fas)-expressing cells, more recent studies pointed out its role in the implementation of non-apoptotic signals. Accordingly, this ligand has been associated with the aggravation of inflammation in different auto-immune disorders and in the metastatic occurrence in different cancers. Although it remains to decipher all key factors involved in the ambivalent role of this ligand, accumulating clues suggest that while the membrane bound CD95L triggers apoptosis, its soluble counterpart generated by metalloprotease-driven cleavage is responsible for its non-apoptotic functions. Nonetheless, the metalloproteases (MMPs and ADAMs) involved in the CD95L shedding, the cleavage sites and the different stoichiometries and functions of the soluble CD95L remain to be elucidated. To better understand how soluble CD95L triggers signaling pathways from apoptosis to inflammation or cell migration, we propose herein to summarize the different metalloproteases that have been described to be able to shed CD95L, their cleavage sites and the biological functions associated with the released ligands. Based on these new findings, the development of CD95/CD95L-targeting therapeutics is also discussed.

MMP7 cleavage of amino-terminal CD95 death receptor switches signaling toward non-apoptotic pathways.

CD95 is a death receptor that can promote oncogenesis through molecular mechanisms that are not fully elucidated. Although the mature CD95 membrane receptor is considered to start with the arginine at position 17 after elimination of the signal peptide, this receptor can also be cleaved by MMP7 upstream of its leucine at position 37. This post-translational modification occurs in cancer cells but also in normal cells such as peripheral blood leukocytes. The non-cleaved CD95 amino-terminal region consists in a disordered domain and its in silico reconstitution suggests that it might contribute to receptor aggregation and thereby, regulate the downstream death signaling pathways. In agreement with this molecular modeling analysis, the comparison of CD95-deficient cells reconstituted with full-length or N-terminally truncated CD95 reveals that the loss of the amino-terminal region of CD95 impairs the initial steps of the apoptotic signal while favoring the induction of pro-survival signals, including the PI3K and MAPK pathways.

Conserved meningeal lymphatic drainage circuits in mice and humans.

Meningeal lymphatic vessels (MLVs) were identified in the dorsal and caudobasal regions of the dura mater, where they ensure waste product elimination and immune surveillance of brain tissues. Whether MLVs exist in the anterior part of the murine and human skull and how they connect with the glymphatic system and extracranial lymphatics remained unclear. Here, we used light-sheet fluorescence microscopy (LSFM) imaging of mouse whole-head preparations after OVA-A555 tracer injection into the cerebrospinal fluid (CSF) and performed real-time vessel-wall (VW) magnetic resonance imaging (VW-MRI) after systemic injection of gadobutrol in patients with neurological pathologies. We observed a conserved three-dimensional anatomy of MLVs in mice and humans that aligned with dural venous sinuses but not with nasal CSF outflow, and we discovered an extended anterior MLV network around the cavernous sinus, with exit routes through the foramina of emissary veins. VW-MRI may provide a diagnostic tool for patients with CSF drainage defects and neurological diseases.

Soluble CD95L in cancers and chronic inflammatory disorders, a new therapeutic target?

Although CD95L (also known as FasL) is still predominantly considered as a death ligand that induces apoptosis in infected and transformed cells, substantial evidence indicate that it can also trigger non-apoptotic signaling pathways whose pathophysiological roles remain to be fully elucidated. The transmembrane ligand CD95L belongs to the tumor necrosis factor (TNF) superfamily. After cleavage by metalloprotease, its soluble form (s-CD95L) fails to trigger the apoptotic program but instead induces signaling pathways promoting the aggressiveness of certain inflammatory disorders such as autoimmune diseases and cancers. We propose to evaluate the various pathologies in which the metalloprotease-cleaved CD95L is accumulated and analyze whether this soluble ligand may play a significant role in the pathology progression. Based on the TNFα-targeting therapeutics, we envision that targeting the soluble form of CD95L may represent a very attractive therapeutic option in the pathologies depicted herein.

Correlative analysis of embedded silicon interface passivation by Kelvin probe force microscopy and corona oxide characterization of semiconductor.

We report a correlative analysis between corona oxide characterization of semiconductor (COCOS) and Kelvin probe force microscopy (KPFM) in a study of embedded silicon surfaces in the field of chemical and field-effect passivation. The COCOS approach gives access to the defect density, the total charge contained in the passivation stack, and the potential barrier. Based on the COCOS parameters, we could probe by KPFM to analyze the influence of the passivation stack upon the surface photovoltage. Thus, KPFM emerges as a valuable method to access chemical and field-effect passivation directly. We confirm that it is possible to differentiate by KPFM the influence of local band bending (i.e., field-effect passivation) from the effects due to the local recombination rates (i.e., chemical passivation). The measurements were carried on five different passivation layers of different thicknesses, precisely, 10.5 nm SiO2, 50 nm SiN, 7 nm Al2O3, 7 nm HfO2, and a double layer of 7 nm Al2O3 below 53 nm Ta2O5. Based on our correlative analysis, we could identify by KPFM that HfO2 displays the best chemical passivation properties. Additionally, we confirm that using an anti-reflective coating such as a Ta2O5 layer on top of Al2O3 causes the chemical passivation to deteriorate. Finally, for p-type silicon, SiN appears to be the worst case in terms of field-effect passivation.

Ex vivo potential of a quinoline-derivative nail lacquer as a new alternative for dermatophytic onychomycosis treatment.

Introduction. Onychomycosis infections currently show a significant increase, affecting about 10 % of the world population. Trichophyton rubrum is the main agent responsible for about 80 % of the reported infections. The clinical cure for onychomycosis is extremely difficult and effective new antifungal therapy is needed.Hypothesis/Gap Statement. Ex vivo onychomycosis models using porcine hooves can be an excellent alternative for evaluating the efficacy of new anti-dermatophytic agents in a nail lacquer.Aim. Evaluation of the effectiveness of a nail lacquer containing a quinoline derivative on an ex vivo onychomycosis model using porcine hooves, as well as the proposal of a plausible antifungal mechanism of this derivative against dermatophytic strains.Methodology. The action mechanism of a quinoline derivative was evaluated through the sorbitol protection assay, exogenous ergosterol binding, and the determination of the dose-response curves by time-kill assay. Scanning electron microscopy evaluated the effect of the derivative in the fungal cells. The efficacy of a quinoline-derivative nail lacquer on an ex vivo onychomycosis model using porcine hooves was evaluated as well.Results. The quinoline derivative showed a time-dependent fungicidal effect, demonstrating reduction and damage in the morphology of dermatophytic hyphae. In addition, the ex vivo onychomycosis model was effective in the establishment of infection by T. rubrum.Conclusion. Treatment with the quinoline-derivative lacquer showed a significant inhibitory effect on T. rubrum strain in this infection model. Finally, the compound presents high potential for application in a formulation such as nail lacquer as a possible treatment for dermatophytic onychomycosis.

Synthesis and evaluation of amides surrogates of dopamine D3 receptor ligands.

Isosteric replacement of the amide function and modulation of the arylpiperazine moiety of known dopamine D3 receptor ligands led to potent and selective compounds. Enhanced bioavailability and preferential brain distribution make compound 6c a good candidate for pharmacological and clinical evaluation.

CD95 Structure, Aggregation and Cell Signaling.

CD95 is a pre-ligand-associated transmembrane (TM) receptor. The interaction with its ligand CD95L brings to a next level its aggregation and triggers different signaling pathways, leading to cell motility, differentiation or cell death. This diversity of biological responses associated with a unique receptor devoid of enzymatic property raises the question of whether different ligands exist, or whether the fine-tuned control of CD95 aggregation and conformation, its distribution within certain plasma membrane sub-domains or the pattern of post-translational modifications account for this such broad-range of cell signaling. Herein, we review how the different domains of CD95 and their post-translational modifications or the different forms of CD95L can participate in the receptor aggregation and induction of cell signaling. Understanding how CD95 response goes from cell death to cell proliferation, differentiation and motility is a prerequisite to reveal novel therapeutic options to treat chronic inflammatory disorders and cancers.

Quinolines derivatives as promising new antifungal candidates for the treatment of candidiasis and dermatophytosis.

Fungal infections have emerged as a current serious global public health problem. The main problem involving these infections is the expansion of multidrug resistance. Therefore, the prospection of new compounds with efficacy antifungal becomes necessary. Thus, this study evaluated the antifungal profile and toxicological parameters of quinolines derivatives against Candida spp. and dermatophyte strains. As a result, a selective anti-dermatophytic action was demonstrated by compound 5 (geometric means (GM = 19.14 µg ml-1)). However, compounds 2 (GM = 50 µg ml-1) and 3 (GM = 47.19 µg ml-1) have presented only anti-Candida action. Compounds 3 and 5 did not present cytotoxic action. Compound 5 did not produce dermal and mucosal toxicity. In addition, this compound showed the absence of genotoxic potential, suggesting safety for topical and systemic use. Quinolines demonstrated a potent anti-dermatophytic and anti-yeast action. Moreover, compound 5 presented an excellent toxicological profile, acting as a strong candidate for the development of a new effective and safe compound against dermatophytosis of difficult treatment.