Recent Advances in the Synthesis and Application of SF5-Containing Organic Compounds

It is well known that fluorinated molecules play an important role in daily life. For example, organic molecules bearing either a fluorine atom itself or a short polyfluorinated substituent such as mono-, difluoro-, and trifluoromethyl groups, or pentafluoroethyl and perfluoropropyl groups are already widely used in medicinal and agricultural chemistry. In contrast, molecules with long perfluorinated chains have found vast application in materials science. Among the fluorine-containing moieties, the pentafluorosulfanyl (SF5) substituent occupies a special place.1 The pentafluorosulfanyl group brings unique properties to organic compounds and often improves their biological activities due to the group’s high chemical and metabolic stability, significant lipophilicity, substantial steric effect, unique geometry, and low surface energy. Here we present new routes towards SF5-substituted aliphatic and heterocyclic compounds

Forced exercise-induced osteoarthritis is attenuated in mice lacking the small leucine-rich proteoglycan decorin

Objective Interterritorial regions of articular cartilage matrix are rich in decorin, a small leucine-rich proteoglycan and important structural protein, also involved in many signalling events. Decorin sequesters transforming growth factor P (TGFP3), thereby regulating its activity. Here, we analysed whether increased bioavailability of TGF3 in decorin-deficient (Dcn(-/-)) cartilage leads to changes in biomechanical properties and resistance to osteoarthritis (OA). Methods Unchallenged knee cartilage was analysed by atomic force microscopy (AFM) and immunohistochemistry. Active transforming growth factor beta-1 (TGF beta 1) content within cultured chondrocyte supernatants was measured by ELISA. Quantitative realtime (RT)-PCR was used to analyse mRNA expression of glycosaminoglycan (GAG)-modifying enzymes in C28/12 cells following TGFf31 treatment. In addition, OA was induced in Dcn(-/-) and wild-type (WT) mice via forced exercise on a treadmill. Results AFM analysis revealed a strikingly higher compressive stiffness in Dcn(-/-) than in WT cartilage. This was accompanied by increased negative charge and enhanced sulfation of GAG chains, but not by alterations in the levels of collagens or proteoglycan core proteins. In addition, decorin-deficient chondrocytes were shown to release more active TGF beta 1. Increased TGF beta signalling led to enhanced Chstl 1 sulfotransferase expression inducing an increased negative charge density of cartilage matrix. These negative charges might attract more water resulting in augmented compressive stiffness of the tissue. Therefore, decorin-deficient mice developed significantly less OA after forced exercise than WT mice. Conclusions Our study demonstrates that the disruption of decorin -restricted TGF beta signalling leads to higher stiffness of articular cartilage matrix, rendering joints more resistant to OA. Therefore, the loss of an important structural component can improve cartilage homeostasis

Disrupting the HDAC6-ubiquitin interaction impairs infection by influenza and Zika virus and cellular stress pathways.

The deacetylase HDAC6 has tandem catalytic domains and a zinc finger domain (ZnF) binding ubiquitin (Ub). While the catalytic domain has an antiviral effect, the ZnF facilitates influenza A virus (IAV) infection and cellular stress responses. By recruiting Ub via the ZnF, HDAC6 promotes the formation of aggresomes and stress granules (SGs), dynamic structures associated with pathologies such as neurodegeneration. IAV subverts the aggresome/HDAC6 pathway to facilitate capsid uncoating during early infection. To target this pathway, we generate designed ankyrin repeat proteins (DARPins) binding the ZnF; one of these prevents interaction with Ub in vitro and in cells. Crystallographic analysis shows that it blocks the ZnF pocket where Ub engages. Conditional expression of this DARPin reversibly impairs infection by IAV and Zika virus; moreover, SGs and aggresomes are downregulated. These results validate the HDAC6 ZnF as an attractive target for drug discovery

Structural basis of adenylyl cyclase 9 activation

Adenylyl cyclase 9 (AC9) is a membrane-bound enzyme that converts ATP into cAMP. The enzyme is weakly activated by forskolin, fully activated by the G protein Gαs subunit and is autoinhibited by the AC9 C-terminus. Although our recent structural studies of the AC9-Gαs complex provided the framework for understanding AC9 autoinhibition, the conformational changes that AC9 undergoes in response to activator binding remains poorly understood. Here, we present the cryo-EM structures of AC9 in several distinct states: (i) AC9 bound to a nucleotide inhibitor MANT-GTP, (ii) bound to an artificial activator (DARPin C4) and MANT-GTP, (iii) bound to DARPin C4 and a nucleotide analogue ATPαS, (iv) bound to Gαs and MANT-GTP. The artificial activator DARPin C4 partially activates AC9 by binding at a site that overlaps with the Gαs binding site. Together with the previously observed occluded and forskolin-bound conformations, structural comparisons of AC9 in the four conformations described here show that secondary structure rearrangements in the region surrounding the forskolin binding site are essential for AC9 activation

Disrupting the HDAC6-ubiquitin interaction impairs infection by influenza and Zika virus and cellular stress pathways

The deacetylase HDAC6 has tandem catalytic domains and a zinc finger domain (ZnF) binding ubiquitin (Ub). While the catalytic domain has an antiviral effect, the ZnF facilitates influenza A virus (IAV) infection and cellular stress responses. By recruiting Ub via the ZnF, HDAC6 promotes the formation of aggresomes and stress granules (SGs), dynamic structures associated with pathologies such as neurodegeneration. IAV subverts the aggresome/HDAC6 pathway to facilitate capsid uncoating during early infection. To target this pathway, we generate designed ankyrin repeat proteins (DARPins) binding the ZnF; one of these prevents interaction with Ub in vitro and in cells. Crystallographic analysis shows that it blocks the ZnF pocket where Ub engages. Conditional expression of this DARPin reversibly impairs infection by IAV and Zika virus; moreover, SGs and aggresomes are downregulated. These results validate the HDAC6 ZnF as an attractive target for drug discovery

Structural basis of adenylyl cyclase 9 activation

Adenylyl cyclase 9 (AC9) is a membrane-bound enzyme that converts ATP into cAMP. The enzyme is weakly activated by forskolin, fully activated by the G protein Gαs subunit and is autoinhibited by the AC9 C-terminus. Although our recent structural studies of the AC9-Gαs complex provided the framework for understanding AC9 autoinhibition, the conformational changes that AC9 undergoes in response to activator binding remains poorly understood. Here, we present the cryo-EM structures of AC9 in several distinct states: (i) AC9 bound to a nucleotide inhibitor MANT-GTP, (ii) bound to an artificial activator (DARPin C4) and MANT-GTP, (iii) bound to DARPin C4 and a nucleotide analogue ATPαS, (iv) bound to Gαs and MANT-GTP. The artificial activator DARPin C4 partially activates AC9 by binding at a site that overlaps with the Gαs binding site. Together with the previously observed occluded and forskolin-bound conformations, structural comparisons of AC9 in the four conformations described here show that secondary structure rearrangements in the region surrounding the forskolin binding site are essential for AC9 activation

DARPins detect the formation of hetero-tetramers of p63 and p73 in epithelial tissues and in squamous cell carcinoma

The two p53 homologues p63 and p73 regulate transcriptional programs in epithelial tissues and several cell types in these tissues express both proteins. All members of the p53 family form tetramers in their active state through a dedicated oligomerization domain that structurally assembles as a dimer of dimers. The oligomerization domain of p63 and p73 share a high sequence identity, but the p53 oligomerization domain is more divergent and it lacks a functionally important C-terminal helix present in the other two family members. Based on these structural differences, p53 does not hetero-oligomerize with p63 or p73. In contrast, p63 and p73 form hetero-oligomers of all possible stoichiometries, with the hetero-tetramer built from a p63 dimer and a p73 dimer being thermodynamically more stable than the two homo-tetramers. This predicts that in cells expressing both proteins a p63$_{2}$/p73$_{2}$ hetero-tetramer is formed. So far, the tools to investigate the biological function of this hetero-tetramer have been missing. Here we report the generation and characterization of Designed Ankyrin Repeat Proteins (DARPins) that bind with high affinity and selectivity to the p63$_{2}$/p73$_{2}$ hetero-tetramer. Using these DARPins we were able to confirm experimentally the existence of this hetero-tetramer in epithelial mouse and human tissues and show that its level increases in squamous cell carcinoma

When Are Three Voters Enough for Privacy Properties?

International audienceProtocols for secure electronic voting are of increasing societal importance. Proving rigorously their security is more challenging than many other protocols, which aim at authentication or key exchange. One of the reasons is that they need to be secure for an arbitrary number of malicious voters. In this paper we identify a class of voting protocols for which only a small number of agents needs to be considered: if there is an attack on vote privacy then there is also an attack that involves at most 3 voters (2 honest voters and 1 dishonest voter). In the case where the protocol allows a voter to cast several votes and counts, e.g., only the last one, we also reduce the number of ballots required for an attack to 10, and under some additional hypotheses, 7 ballots. Our results are formalised and proven in a symbolic model based on the applied pi calculus. We illustrate the applicability of our results on several case studies, including different versions of Helios and Prêt-` a-Voter, as well as the JCJ protocol. For some of these protocols we can use the ProVerif tool to provide the first formal proofs of privacy for an unbounded number of voters

Enforcing Privacy in the Presence of Others: Notions, Formalisations and Relations

Protecting privacy against bribery/coercion is a necessary requirement in electronic services, like e-voting, e-auction and e-health. Domain-specific privacy properties have been proposed to capture this. We generalise these properties as enforced privacy: a system enforces a user's privacy even when the user collaborates with the adversary. In addition, we account for the influence of third parties on a user's privacy. Third parties can help to break privacy by collaborating with the adversary, or can help to protect privacy by cooperating with the target user. We propose independency of privacy to capture the negative privacy impact that third parties can have, and coalition privacy to capture their positive privacy impact. We formally define these privacy notions in the applied pi calculus and build a hierarchy showing their relations