Guanidinium-Stapled Helical Peptides for Targeting Protein-Protein Interactions.

Peptide stapling has emerged as a versatile approach in drug discovery to reinforce secondary structure elements especially α-helices and improve properties of linear bioactive peptides. Inspired by the prevalence of arginine in protein-protein and protein-DNA interfaces, we investigated guanidinium-stapling as a means to constrain helical peptides. Guanidinium stapling was readily achieved on solid support, utilizing two orthogonally protected lysine or unatural α-amino acid residues with an amino function.

Retinoids Molecular Probes by Late-stage Azide Insertion - Functional Tools to Decrypt Retinoid Metabolism.

Studying the complex and intricate retinoids metabolic pathways by chemical biology approaches requires design and synthesis of biologically functional molecular probes. Only few of such molecular retinoid probes could be found in literature, most of them bearing a molecular structure quite different from natural retinoids. To provide close-to-native retinoid probes, we have developed a versatile late-stage method for the insertion of azide function at the C4 position of several retinoids.

A vitamin D-based strategy overcomes chemoresistance in prostate cancer.

Background And Purpose: Castration-resistant prostate cancer (CRPC) is a common male malignancy that requires new therapeutic strategies due to acquired resistance to its first-line treatment, docetaxel. The benefits of vitamin D on prostate cancer (PCa) progression have been previously reported. This study aimed to investigate the effects of vitamin D on chemoresistance in CRPC.

Design, Synthesis, and Biological Evaluation of New Type of Gemini Analogues with a Cyclopropane Moiety in Their Side Chain.

We synthesized two new gemini analogues, and , that incorporate a modified longer side chain containing a cyclopropane group. The evaluation of the bioactivities of the two gemini analogues indicated that the 17,20 threo (20) compound, , is the most active one and is as active as 1,25(OH)D. Docking and molecular dynamics (MD) data showed that the compounds bind efficiently to vitamin D receptor (VDR) with to form an energetically more favorable interaction with His397.

4-Hydroxy-1α,25-Dihydroxyvitamin D: Synthesis and Structure-Function Study.

The active vitamin D metabolites, 25-hydroxyvitamin D (25D) and 1,25-dihydroxyvitamin D (1,25D), are produced by successive hydroxylation steps and play key roles in several cellular processes. However, alternative metabolic pathways exist, and among them, the 4-hydroxylation of 25D is a major one. This study aims to investigate the structure-activity relationships of 4-hydroxy derivatives of 1,25D.

Design, synthesis, and biological activity of D-bishomo-1α,25-dihydroxyvitamin D analogs and their crystal structures with the vitamin D nuclear receptor.

The biologically active metabolite of vitamin D - calcitriol - is a hormone involved in the regulation of calcium-phosphate homeostasis, immunological processes and cell differentiation, being therefore essential for the proper functioning of the human body. This suggests many applications of this steroid in the treatment of diseases such as rickets, psoriasis and some cancers. Unfortunately, using therapeutic doses of calcitriol is associated with high concentrations of this compound which causes hypercalcemia.

Further Studies on the Highly Active Des-C-Ring and Aromatic-D-Ring Analogues of 1α,25-Dihydroxyvitamin D (Calcitriol): Refinement of the Side Chain.

Current efforts in the vitamin D field are directed toward the development of highly antiproliferative yet noncalcemic analogues of the natural hormone 1α,25-dihydroxyvitamin D (1,25D). We have recently reported the design, synthesis, biological evaluation, and crystal structures of a series of novel analogues that both lack the steroidal C-ring and have an -phenylene ring replacing the steroidal cyclopentane D-ring. We have now investigated the potentiating effects of incorporating selected modifications (hexafluorination and/or an internal triple bond) within the steroidal side chain in our series.

Vitamin D Receptor Antagonist MeTC7 Inhibits PD-L1.

Small-molecule inhibitors of PD-L1 are postulated to control immune evasion in tumors similar to antibodies that target the PD-L1/PD-1 immune checkpoint axis. However, the identity of targetable PD-L1 inducers is required to develop small-molecule PD-L1 inhibitors. In this study, using chromatin immunoprecipitation (ChIP) assay and siRNA, we demonstrate that vitamin D/VDR regulates PD-L1 expression in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) cells.

Structural analysis and biological activities of C25-amino and C25-nitro vitamin D analogs.

Intense synthetic efforts have been directed towards the development of noncalcemic analogs of 1,25-dihydroxyvitamin D. We describe here the structural analysis and biological evaluation of two derivatives of 1,25-dihydroxyvitamin D with modifications limited to the replacement of the 25-hydroxyl group by a 25-amino or 25-nitro groups. Both compounds are agonists of the vitamin D receptor.

FGFR3 Mutational Activation Can Induce Luminal-like Papillary Bladder Tumor Formation and Favors a Male Sex Bias.

Background: Bladder cancer (BCa) is more common in men and presents differences in molecular subtypes based on sex. Fibroblast growth factor receptor 3 (FGFR3) mutations are enriched in the luminal papillary muscle-invasive BCa (MIBC) and non-MIBC subtypes.

Objective: To determine whether FGFR3 mutations initiate BCa and impact BCa male sex bias.

Design, Synthesis, Biological Activity, and Structural Analysis of Novel Des-C-Ring and Aromatic-D-Ring Analogues of 1α,25-Dihydroxyvitamin D.

The toxic calcemic effects of the natural hormone 1α,25-dihydroxyvitamin D (1,25D, 1,25-dihydroxycholecalciferol) in the treatment of hyperproliferative diseases demand the development of highly active and noncalcemic vitamin D analogues. We report the development of two highly active and noncalcemic analogues of 1,25D that lack the C-ring and possess an -phenylene ring that replaces the natural D-ring. The new analogues (, ) are characterized by an additional six-carbon hydroxylated side chain attached either to the aromatic nucleus or to the triene system.

Vitamin D Analogs Bearing C-20 Modifications Stabilize the Agonistic Conformation of Non-Responsive Vitamin D Receptor Variants.

The Vitamin D receptor (VDR) plays a key role in calcium homeostasis, as well as in cell proliferation and differentiation. Among the large number of VDR ligands that have been developed, we have previously shown that BXL-62 and Gemini-72, two C-20-modified vitamin D analogs are highly potent VDR agonists. In this study, we show that both VDR ligands restore the transcriptional activities of VDR variants unresponsive to the natural ligand and identified in patients with rickets.

Vitamin D and Its Receptor from a Structural Perspective.

The activities of 1α,25-dihydroxyvitamin D3, 1,25D, are mediated via its binding to the vitamin D receptor (VDR), a ligand-dependent transcription factor that belongs to the nuclear receptor superfamily. Numerous studies have demonstrated the important role of 1,25D and VDR signaling in various biological processes and associated pathologies. A wealth of information about ligand recognition and mechanism of action by structural analysis of the VDR complexes is also available.

Advances in Vitamin D Receptor Function and Evolution Based on the 3D Structure of the Lamprey Ligand-Binding Domain.

1α,25-dihydroxyvitamin D3 (1,25D) regulates many physiological processes in vertebrates by binding to the vitamin D receptor (VDR). Phylogenetic analysis indicates that jawless fishes are the most basal vertebrates exhibiting a VDR gene. To elucidate the mechanism driving VDR activation during evolution, we determined the crystal structure of the VDR ligand-binding domain (LBD) complex from the basal vertebrate, sea lamprey (lVDR).

HR-Bac, a toolbox based on homologous recombination for expression, screening and production of multiprotein complexes using the baculovirus expression system.

The Baculovirus/insect cell expression system is a powerful technology for reconstitution of eukaryotic macromolecular assemblies. Most multigene expression platforms rely on Tn7-mediated transposition for transferring the expression cassette into the baculoviral genome. This allows a rigorous characterization of recombinant bacmids but involves multiple steps, a limitation when many constructs are to be tested.

Biological evaluation and synthesis of calcitroic acid.

We describe the synthesis and broad profiling of calcitroic acid (CTA) as vitamin D receptor (VDR) ligand. The x-ray co-crystal structure of the Danio Rerio VDR ligand binding domain in complex with CTA and peptide MED1 confirmed an agonistic conformation of the receptor. CTA adopted a similar conformation as 1,25(OH)D in the binding pocket.

Design, synthesis and evaluation of side-chain hydroxylated derivatives of lithocholic acid as potent agonists of the vitamin D receptor (VDR).

A high number of biologically active and low-calcemic secosteroidal ligands of the vitamin D receptor (VDR) have been developed, some of which are already used clinically although with limited success in the treatment of hyperproliferative diseases because the required pharmaceutical dosages induce toxicity. We describe here the in silico design, synthesis, structural analysis and biological evaluation of two novel active lithocholic acid derivatives hydroxylated at the side chain as highly potent inhibitors of atopic dermatitis-relevant keratinocyte inflammation of potential therapeutic interest.

Ligands and DNA in the allosteric control of retinoid receptors function.

Retinoids are a family of compounds that include both vitamin A (all-trans retinol) and its naturally occurring metabolites such as retinoic acids (e.g. all-trans retinoic acid) as well as synthetic analogs.

Design, Synthesis, Evaluation and Structure of Allenic 1α,25-Dihydroxyvitamin D Analogs with Locked Mobility at C-17.

Vitamin D receptor ligands have potential for the treatment of hyperproliferative diseases and disorders related to the immune system. However, hypercalcemic effects limit their therapeutical uses and call for the development of tissue-selective new analogs. We have designed and synthesized the first examples of 1α,25-dihydroxyvitamin D analogs bearing an allenic unit attached to the D ring to restrict the side-chain conformational mobility.

Conformational editing of intrinsically disordered protein by α-methylation.

Intrinsically disordered proteins (IDPs) constitute a large portion of "Dark Proteome" - difficult to characterize or yet to be discovered protein structures. Here we used conformationally constrained α-methylated amino acids to bias the conformational ensemble in the free unstructured activation domain of transcriptional coactivator ACTR. Different sites and patterns of substitutions were enabled by chemical protein synthesis and led to distinct populations of α-helices.

Lithocholic acid-based design of noncalcemic vitamin D receptor agonists.

The hypercalcemic effects of the hormone 1α,25-dihydroxyvitamin D (calcitriol) and most of known vitamin D metabolites and analogs call for the development of non secosteroidal vitamin D receptor (VDR) ligands as new selective and noncalcemic agonists for treatment of hyperproliferative diseases. We report on the in silico design and stereoselective synthesis of six lithocholic acid derivatives as well as on the calcemic activity of a potent LCA derivative and its crystallographic structure in complex with zVDR LBD. The low calcemic activity of this compound in comparison with the native hormone makes it of potential therapeutic value.

Cytosolic sequestration of the vitamin D receptor as a therapeutic option for vitamin D-induced hypercalcemia.

The bioactive vitamin D, 1α,25(OH)D, plays a central role in calcium homeostasis by controlling the activity of the vitamin D receptor (VDR) in various tissues. Hypercalcemia secondary to high circulating levels of vitamin D leads to hypercalciuria, nephrocalcinosis and renal dysfunctions. Current therapeutic strategies aim at limiting calcium intake, absorption and resorption, or 1α,25(OH)D synthesis, but are poorly efficient.