N-acylbenzimidazoles as selective Acylators of the catalytic cystein of the coronavirus 3CL protease.

The 3CL protease (3CLpro, Mpro) plays a key role in the replication of the SARS-CoV-2 and was validated as therapeutic target by the development and approval of specific antiviral drugs (nirmatrelvir, ensitrelvir), inhibitors of this protease. Moreover, its high conservation within the coronavirus family renders it an attractive therapeutic target for the development of anti-coronavirus compounds with broad spectrum activity to control COVID-19 and future coronavirus diseases. Here we report on the design, synthesis and structure-activity relationships of a new series of small covalent reversible inhibitors of the SARS-CoV-2 3CLpro. As elucidated thanks to the X-Ray structure of some inhibitors with the 3CLpro, the mode of inhibition involves acylation of the thiol of the catalytic cysteine. The synthesis of 60 analogs led to the identification of compound 56 that inhibits the SARS-CoV-2 3CLpro with high potency (IC50 = 70 nM) and displays antiviral activity in cells (EC50 = 3.1 µM). Notably, compound 56 inhibits the 3CLpro of three other human coronaviruses and exhibit a good selectivity against two human cysteine proteases. These results demonstrate the potential of this electrophilic N-acylbenzimidazole series as a basis for further optimization.

Insulin-degrading enzyme inhibition increases the unfolded protein response and favours lipid accumulation in the liver.

BACKGROUND AND PURPOSE: Nonalcoholic fatty liver disease refers to liver pathologies, ranging from steatosis to steatohepatitis, with fibrosis ultimately leading to cirrhosis and hepatocellular carcinoma. Although several mechanisms have been suggested, including insulin resistance, oxidative stress, and inflammation, its pathophysiology remains imperfectly understood. Over the last decade, a dysfunctional unfolded protein response (UPR) triggered by endoplasmic reticulum (ER) stress emerged as one of the multiple driving factors. In parallel, growing evidence suggests that insulin-degrading enzyme (IDE), a highly conserved and ubiquitously expressed metallo-endopeptidase originally discovered for its role in insulin decay, may regulate ER stress and UPR. EXPERIMENTAL APPROACH: We investigated, by genetic and pharmacological approaches, in vitro and in vivo, whether IDE modulates ER stress-induced UPR and lipid accumulation in the liver. KEY RESULTS: We found that IDE-deficient mice display higher hepatic triglyceride content along with higher inositol-requiring enzyme 1 (IRE1) pathway activation. Upon induction of ER stress by tunicamycin or palmitate in vitro or in vivo, pharmacological inhibition of IDE, using its inhibitor BDM44768, mainly exacerbated ER stress-induced IRE1 activation and promoted lipid accumulation in hepatocytes, effects that were abolished by the IRE1 inhibitors 4µ8c and KIRA6. Finally, we identified that IDE knockout promotes lipolysis in adipose tissue and increases hepatic CD36 expression, which may contribute to steatosis. CONCLUSION AND IMPLICATIONS: These results unravel a novel role for IDE in the regulation of ER stress and development of hepatic steatosis. These findings pave the way to innovative strategies modulating IDE to treat metabolic diseases.

Novel dithiocarbamates selectively inhibit 3CL protease of SARS-CoV-2 and other coronaviruses.

Since end of 2019, the global and unprecedented outbreak caused by the coronavirus SARS-CoV-2 led to dramatic numbers of infections and deaths worldwide. SARS-CoV-2 produces two large viral polyproteins which are cleaved by two cysteine proteases encoded by the virus, the 3CL protease (3CLpro) and the papain-like protease, to generate non-structural proteins essential for the virus life cycle. Both proteases are recognized as promising drug targets for the development of anti-coronavirus chemotherapy. Aiming at identifying broad spectrum agents for the treatment of COVID-19 but also to fight emergent coronaviruses, we focused on 3CLpro that is well conserved within this viral family. Here we present a high-throughput screening of more than 89,000 small molecules that led to the identification of a new chemotype, potent inhibitor of the SARS-CoV-2 3CLpro. The mechanism of inhibition, the interaction with the protease using NMR and X-Ray, the specificity against host cysteine proteases and promising antiviral properties in cells are reported.

Discovery of the First Selective Nanomolar Inhibitors of ERAP2 by Kinetic Target-Guided Synthesis.

Endoplasmic reticulum aminopeptidase 2 (ERAP2) is a key enzyme involved in the trimming of antigenic peptides presented by Major Histocompatibility Complex class I. It is a target of growing interest for the treatment of autoimmune diseases and in cancer immunotherapy. However, the discovery of potent and selective ERAP2 inhibitors is highly challenging. Herein, we have used kinetic target-guided synthesis (KTGS) to identify such inhibitors. Co-crystallization experiments revealed the binding mode of three different inhibitors with increasing potency and selectivity over related enzymes. Selected analogues engage ERAP2 in cells and inhibit antigen presentation in a cellular context. 4 d (BDM88951) displays favorable in vitro ADME properties and in vivo exposure. In summary, KTGS allowed the discovery of the first nanomolar and selective highly promising ERAP2 inhibitors that pave the way of the exploration of the biological roles of this enzyme and provide lead compounds for drug discovery efforts.

Drug Target Engagement Using Coupled Cellular Thermal Shift Assay-Acoustic Reverse-Phase Protein Array.

In the last 5 years, cellular thermal shift assay (CETSA), a technology based on ligand-induced changes in protein thermal stability, has been increasingly used in drug discovery to address the fundamental question of whether drug candidates engage their intended target in a biologically relevant setting. To analyze lysates from cells submitted to increasing temperature, the detection and quantification of the remaining soluble protein can be achieved using quantitative mass spectrometry, Western blotting, or AlphaScreen techniques. Still, these approaches can be time- and cell-consuming. To cope with limitations of throughput and protein amount requirements, we developed a new coupled assay combining the advantages of a nanoacoustic transfer system and reverse-phase protein array technology within CETSA experiments. We validated the technology to assess engagement of inhibitors of insulin-degrading enzyme (IDE), an enzyme involved in diabetes and Alzheimer's disease. CETSA-acoustic reverse-phase protein array (CETSA-aRPPA) allows simultaneous analysis of many conditions and drug-target engagement with a small sample size, in a rapid, cost-effective, and biological material-saving manner.

BIN1 recovers tauopathy-induced long-term memory deficits in mice and interacts with Tau through Thr348 phosphorylation.

The bridging integrator 1 gene (BIN1) is a major genetic risk factor for Alzheimer's disease (AD). In this report, we investigated how BIN1-dependent pathophysiological processes might be associated with Tau. We first generated a cohort of control and transgenic mice either overexpressing human MAPT (TgMAPT) or both human MAPT and BIN1 (TgMAPT;TgBIN1), which we followed-up from 3 to 15 months. In TgMAPT;TgBIN1 mice short-term memory deficits appeared earlier than in TgMAPT mice; however-unlike TgMAPT mice-TgMAPT;TgBIN1 mice did not exhibit any long-term or spatial memory deficits for at least 15 months. After killing the cohort at 18 months, immunohistochemistry revealed that BIN1 overexpression prevents both Tau mislocalization and somatic inclusion in the hippocampus, where an increase in BIN1-Tau interaction was also observed. We then sought mechanisms controlling the BIN1-Tau interaction. We developed a high-content screening approach to characterize modulators of the BIN1-Tau interaction in an agnostic way (1,126 compounds targeting multiple pathways), and we identified-among others-an inhibitor of calcineurin, a Ser/Thr phosphatase. We determined that calcineurin dephosphorylates BIN1 on a cyclin-dependent kinase phosphorylation site at T348, promoting the open conformation of the neuronal BIN1 isoform. Phosphorylation of this site increases the availability of the BIN1 SH3 domain for Tau interaction, as demonstrated by nuclear magnetic resonance experiments and in primary neurons. Finally, we observed that although the levels of the neuronal BIN1 isoform were unchanged in AD brains, phospho-BIN1(T348):BIN1 ratio was increased, suggesting a compensatory mechanism. In conclusion, our data support the idea that BIN1 modulates the AD risk through an intricate regulation of its interaction with Tau. Alteration in BIN1 expression or activity may disrupt this regulatory balance with Tau and have direct effects on learning and memory.

Genome-wide, high-content siRNA screening identifies the Alzheimer's genetic risk factor FERMT2 as a major modulator of APP metabolism.

Genome-wide association studies (GWASs) have identified 19 susceptibility loci for Alzheimer's disease (AD). However, understanding how these genes are involved in the pathophysiology of AD is one of the main challenges of the "post-GWAS" era. At least 123 genes are located within the 19 susceptibility loci; hence, a conventional approach (studying the genes one by one) would not be time- and cost-effective. We therefore developed a genome-wide, high-content siRNA screening approach and used it to assess the functional impact of gene under-expression on APP metabolism. We found that 832 genes modulated APP metabolism. Eight of these genes were located within AD susceptibility loci. Only FERMT2 (a ß3-integrin co-activator) was also significantly associated with a variation in cerebrospinal fluid Aß peptide levels in 2886 AD cases. Lastly, we showed that the under-expression of FERMT2 increases Aß peptide production by raising levels of mature APP at the cell surface and facilitating its recycling. Taken as a whole, our data suggest that FERMT2 modulates the AD risk by regulating APP metabolism and Aß peptide production.

Identification of Small Inhibitory Molecules Targeting the Bfl-1 Anti-Apoptotic Protein That Alleviates Resistance to ABT-737.

One approach currently being developed in anticancer drug discovery is to search for small compounds capable of occupying and blocking the hydrophobic pocket of anti-apoptotic Bcl-2 family members necessary for interacting with pro-apoptotic proteins. Such an approach led to the discovery of several compounds, such as ABT-737 (which interacts with Bcl-2, Bcl-xl, and Bcl-w) or the latest one, ABT-199, that selectively targets Bcl-2 protein. The efficacy of those compounds is, however, limited by the expression of two other anti-apoptotic Bcl-2 members, Mcl-1 and Bfl-1. Based on the role of Bfl-1 in cancer, especially in chemoresistance associated with its overexpression in B-cell malignancies, we searched for modulators of protein-protein interaction through a high-throughput screening of a designed chemical library with relaxed drug-like properties to identify small molecules targeting Bfl-1 anti-apoptotic protein. We found two compounds that display electrophilic functions, interact with Bfl-1, inhibit Bfl-1 protective activity, and promote cell death of malignant B cells. Of particular interest, we observed a synergistic effect of those compounds with ABT-737 in Bfl-1 overexpressing lymphoma cell lines. Our results provide the basis for the development of Bfl-1 specific antagonists for antitumor therapies.

Receptor-interacting protein 140 differentially regulates estrogen receptor-related receptor transactivation depending on target genes.

We have investigated the effects of receptor-interacting protein 140 (RIP140) on transcriptional regulation by estrogen receptor-related receptors (ERRs). We first show that RIP140 inhibits transactivation by ERRalpha, beta, and gamma on natural or artificial reporter genes containing different types of response elements. This repression correlates with a strong in vitro binding between several regions of RIP140 and the three ERR isoforms. Surprisingly, although RIP140 inhibits transactivation of the thyroid hormone receptor-alpha gene by ERRbeta, it significantly increases its regulation by ERRalpha and ERRgamma. Mutagenesis and transient transfections in SL2 cells indicate that thyroid hormone receptor-alpha promoter expression involved Sp1 sites. In support of this observation, we demonstrate that RIP140 also positively regulates ERRs transactivation of other known Sp1 targets such as the p21 gene. This effect requires the two proximal Sp1 binding sites of the promoter and is partially dependent on the activation function 2 domain of ERRs. Finally, we provide evidences for a role of histone deacetylases in the regulation of p21 promoter by RIP140. Altogether, these data indicate that RIP140 differentially regulates ERR activity depending on the target sequence on the promoters.