Project description:Constraining a molecule in its bioactive conformation via macrocyclization represents an attractive strategy to rationally design functional chemical probes. While this approach has been applied to enzyme inhibitors or receptor antagonists, to date it remains unprecedented for bifunctional molecules that bring proteins together, such as PROTAC degraders. Herein, we report the design and synthesis of a macrocyclic PROTAC by adding a cyclizing linker to the BET degrader MZ1. A co-crystal structure of macroPROTAC-1 bound in a ternary complex with VHL and the second bromodomain of Brd4 validated the rational design. Biophysical studies revealed enhanced discrimination between the second and the first bromodomains of BET proteins. Despite a 12-fold loss of binary binding affinity for Brd4, macroPROTAC-1 exhibited cellular activity comparable to MZ1. Our findings support macrocyclization as an advantageous strategy to enhance PROTAC degradation potency and selectivity between homologous targets.
Project description:Thalidomide and its analogues are frequently used in PROTAC design. However, they are known to be inherently unstable, undergoing hydrolysis even in commonly utilized cell culture media. We recently reported that phenyl glutarimide (PG)-based PROTACs displayed improved chemical stability and, consequently, improved protein degradation efficacy and cellular potency. Our optimization efforts, aiming to further improve the chemical stability and eliminate the racemization-prone chiral center in PG, led us to the development of phenyl dihydrouracil (PD)-based PROTACs. Here we describe the design and synthesis of LCK-directing PD-PROTACs and compare their physicochemical and pharmacological properties to those of the corresponding IMiD and PG analogues.
Project description:Proteolysis Targeting Chimera (PROTAC) technology is a rapidly emerging alternative therapeutic strategy with the potential to address many of the challenges currently faced in modern drug development programs. PROTAC technology employs small molecules that recruit target proteins for ubiquitination and removal by the proteasome. The synthesis of PROTAC compounds that mediate the degradation of c-ABL and BCR-ABL by recruiting either Cereblon or Von Hippel Lindau E3 ligases is reported. During the course of their development, we discovered that the capacity of a PROTAC to induce degradation involves more than just target binding: the identity of the inhibitor warhead and the recruited E3 ligase largely determine the degradation profiles of the compounds; thus, as a starting point for PROTAC development, both the target ligand and the recruited E3 ligase should be varied to rapidly generate a PROTAC with the desired degradation profile.
Project description:Inhibiting protein function selectively is a major goal of modern drug discovery. Here, we report a previously understudied benefit of small molecule proteolysis-targeting chimeras (PROTACs) that recruit E3 ubiquitin ligases to target proteins for their ubiquitination and subsequent proteasome-mediated degradation. Using promiscuous CRBN- and VHL-recruiting PROTACs that bind >50 kinases, we show that only a subset of bound targets is degraded. The basis of this selectivity relies on protein-protein interactions between the E3 ubiquitin ligase and the target protein, as illustrated by engaged proteins that are not degraded as a result of unstable ternary complexes with PROTAC-recruited E3 ligases. In contrast, weak PROTAC:target protein affinity can be stabilized by high-affinity target:PROTAC:ligase trimer interactions, leading to efficient degradation. This study highlights design guidelines for generating potent PROTACs as well as possibilities for degrading undruggable proteins immune to traditional small-molecule inhibitors.
Project description:PROteolysis TArgeting Chimeras (PROTACs) are heterobifunctional molecules consisting of two ligands; an "anchor" to bind to an E3 ubiquitin ligase and a "warhead" to bind to a protein of interest, connected by a chemical linker. Targeted protein degradation by PROTACs has emerged as a new modality for the knock down of a range of proteins, with the first agents now reaching clinical evaluation. It has become increasingly clear that the length and composition of the linker play critical roles on the physicochemical properties and bioactivity of PROTACs. While linker design has historically received limited attention, the PROTAC field is evolving rapidly and currently undergoing an important shift from synthetically tractable alkyl and polyethylene glycol to more sophisticated functional linkers. This promises to unlock a wealth of novel PROTAC agents with enhanced bioactivity for therapeutic intervention. Here, the authors provide a timely overview of the diverse linker classes in the published literature, along with their underlying design principles and overall influence on the properties and bioactivity of the associated PROTACs. Finally, the authors provide a critical analysis of current strategies for PROTAC assembly. The authors highlight important limitations associated with the traditional "trial and error" approach around linker design and selection, and suggest potential future avenues to further inform rational linker design and accelerate the identification of optimised PROTACs. In particular, the authors believe that advances in computational and structural methods will play an essential role to gain a better understanding of the structure and dynamics of PROTAC ternary complexes, and will be essential to address the current gaps in knowledge associated with PROTAC design.
Project description:Targeting subunits of BAF/PBAF chromatin remodeling complexes has been proposed as an approach to exploit cancer vulnerabilities. Here, we develop proteolysis targeting chimera (PROTAC) degraders of the BAF ATPase subunits SMARCA2 and SMARCA4 using a bromodomain ligand and recruitment of the E3 ubiquitin ligase VHL. High-resolution ternary complex crystal structures and biophysical investigation guided rational and efficient optimization toward ACBI1, a potent and cooperative degrader of SMARCA2, SMARCA4 and PBRM1. ACBI1 induced anti-proliferative effects and cell death caused by SMARCA2 depletion in SMARCA4 mutant cancer cells, and in acute myeloid leukemia cells dependent on SMARCA4 ATPase activity. These findings exemplify a successful biophysics- and structure-based PROTAC design approach to degrade high profile drug targets, and pave the way toward new therapeutics for the treatment of tumors sensitive to the loss of BAF complex ATPases.
Project description:Cortisol is established as a reliable biomarker for stress prompting intensified research in developing wearable sensors to detect it via eccrine sweat. Since cortisol is present in sweat in trace quantities, typically 8-140 ng/mL, developing such biosensors necessitates the design of bioreceptors with appropriate sensitivity and selectivity. In this work, we present a systematic biomimetic methodology and a semi-automated high-throughput screening tool which enables rapid selection of bioreceptors as compared to ab initio design of peptides via computational peptidology. Candidate proteins from databases are selected via molecular docking and ranked according to their binding affinities by conducting automated AutoDock Vina scoring simulations. These candidate proteins are then validated via full atomistic steered molecular dynamics computations including umbrella sampling to estimate the potential of mean force using GROMACS version 2022.6. These explicit molecular dynamic calculations are carried out in an eccrine sweat environment taking into consideration the protein dynamics and solvent effects. Subsequently, we present a candidate baseline peptide bioreceptor selected as a contiguous sequence of amino acids from the selected protein binding pocket favourably interacting with the target ligand (i.e., cortisol) from the active binding site of the proteins and maintaining its tertiary structure. A unique cysteine residue introduced at the N-terminus allows orientation-specific surface immobilization of the peptide onto the gold electrodes and to ensure exposure of the binding site. Comparative binding affinity simulations of this peptide with the target ligand along with commonly interfering species e.g., progesterone, testosterone and glucose are also presented to demonstrate the validity of this proposed peptide as a candidate baseline bioreceptor for future cortisol biosensor development.
Project description:Indoleamine 2,3-dioxygenase 1 (IDO1) is an immunosuppressive protein that inhibits antitumor immunity through both tryptophan metabolism and nonenzymatic functions. Drugs targeting IDO1 enzyme activity have failed to improve the overall survival of patients with cancer. Developing new therapeutics that neutralize both enzyme- and nonenzyme-derived immunosuppressive IDO1 effects is therefore of high interest. We previously described a novel proteolysis targeting chimera (PROTAC), NU223612, that degrades IDO1 in cultured human glioblastoma (GBM) cells, as well as in well-established brain tumors, in vivo. In this study, we rationally optimized the structure of our lead series to create NU227326, which degrades IDO1 with a DC50 of 5 nM in human GBM cells. Mechanistic studies showed that IDO1 degradation occurred through the ubiquitin-proteasome system and was sustained for at least 2 days, supporting NU227326 as a highly potent IDO1 PROTAC suitable for further studies in GBM and other human cancers.
Project description:Our genotype inference method combines sparse marker data from a linkage scan and high-resolution SNP genotypes for several individuals to infer genotypes for related individuals. We illustrate the method's utility by inferring over 53 million SNP genotypes for 78 children in the Centre d'Etude du Polymorphisme Humain families. The method can be used to obtain high-density genotypes in different family structures, including nuclear families commonly used in complex disease gene mapping studies.
Project description:Protein N-terminal methylation catalyzed by N-terminal methyltransferase 1 (NTMT1) is an emerging methylation present in eukaryotes, playing important regulatory roles in various biological and cellular processes. Although dysregulation of NTMT1 has been linked to many diseases such as colorectal cancer, their molecular and cellular mechanisms remain elusive due to inaccessibility to an effective cellular probe. Here we report the design, synthesis, and characterization of the first-in-class NTMT1 degraders based on proteolysis-targeting chimera (PROTAC) strategy. Through a brief structure-activity relationship (SAR) study of linker length, a cell permeable degrader 1 involving a von Hippel-Lindau (VHL) E3 ligase ligand was developed and demonstrated to reduce NTMT1 protein levels effectively and selectively in time- and dose-dependent manners in colorectal carcinoma cell lines HCT116 and HT29. Degrader 1 displayed DC50 = 7.53 μM and Dmax > 90% in HCT116 (cellular IC50 > 100 μM for its parent inhibitor DC541). While degrader 1 had marginal cytotoxicity, it displayed anti-proliferative activity in 2D and 3D culture environment, resulting from cell cycle arrested at G0/G1 phase in HCT116. Label-free global proteomic analysis revealed that degrader 1 induced overexpression of calreticulin (CALR), an immunogenic cell death (ICD) signal protein that is known to elicit antitumor immune response and clinically linked to a high survival rate of patients with colorectal cancer upon its upregulation. Collectively, degrader 1 offers the first selective cellular probe for NTMT1 exploration and a new drug discovery modality for NTMT1-related oncology and diseases.