Differing pharmacological activities of thiazolidinone analogs at the FSH receptor

The follicle-stimulating hormone is critical to reproductive success and is an important target for development of novel reproductive therapies. We have recently reported the development of thiazolidinone positive allosteric modulators of the follicle-stimulating hormone receptor. Here, we demonstrate that discrete modifications in the chemical structure of the thiazolidinone agonists produced compounds with different pharmacological properties. Positive allosteric modulators activated adenylate cyclase signaling (Gs). Using an ADP-ribosylation assay we found that both differing glycosylated variants of human FSH (hFSH) and selected thiazolidinone allosteric modulators of the FSHR induce activation of the Gi signaling pathway. Additionally, we observed that some analogs of this class could activate both pathways. These data suggest that the pharmacological activity of thiazolidinone modulators to the FSHR may be due to the ability of these compounds to induce association of the FSHR with either Gs or Gi signaling pathways in an analog-specific manner.     

Identification of novel allosteric modulators for the G-protein coupled US28 receptor of human cytomegalovirus

The highly constitutively active G-protein coupled receptor US28 of human cytomegalovirus (HCMV) is an interesting pharmacological target because of its implication on viral dissemination, cardiovascular diseases and tumorigenesis. We found that dihydroisoquinolinone and tetrahydroisoquinoline scaffolds may be promising lead structures for novel US28 allosteric inverse agonists. These scaffolds were rapidly synthesized by radical carboamination reactions followed by non-radical transformations. Our novel US28 allosteric modulators provide valuable scaffolds for further ligand optimization and may be helpful chemical tools to investigate molecular mechanisms of US28 constitutive signaling and its role in pathogenesis.     

Novel lead for potent inhibitors of breast cancer resistance protein (BCRP)

From our modulator library an interesting inhibitor of breast cancer resistance protein (BCRP) was identified. Due to its high inhibitory potency, this compound may serve as a promising novel lead for the design of new and potent modulators. This adds a new structural class to the few known highly active BCRP inhibitors.     

Pharmacological characterization of AC-262536, a novel selective androgen receptor modulator

Because of the limitations and liabilities of current testosterone therapies, non-steroidal tissue-selective androgen receptor modulators may provide a clinically meaningful advance in therapy. Using a functional cell-based assay AC-262536 was identified as a potent and selective AR ligand, with partial agonist activity relative to the natural androgen testosterone. A 2-week chronic study in castrated male rats indicated that AC-262536 significantly improves anabolic parameters in these animals, especially in stimulating the growth of the levator ani and in suppressing elevated LH levels. In sharp contrast to testosterone, AC-262536 has weak androgenic effects, as measured by prostate and seminal vesicle weights. Thus, AC-262536 represents a novel class of selective androgen receptor modulators (SARMs) with beneficial anabolic effects.     

Small Molecule Inhibitors of Phospholipase C from a Novel High-throughput Screen

Phospholipase C (PLC) isozymes are important signaling molecules, but few small molecule modulators are available to pharmacologically regulate their function. With the goal of developing a general approach for identification of novel PLC inhibitors, we developed a high-throughput assay based on the fluorogenic substrate reporter WH-15. The assay is highly sensitive and reproducible: screening a chemical library of 6280 compounds identified three novel PLC inhibitors that exhibited potent activities in two separate assay formats with purified PLC isozymes in vitro. Two of the three inhibitors also inhibited G protein-coupled receptor-stimulated PLC activity in intact cell systems. These results demonstrate the power of the high-throughput assay for screening large collections of small molecules to identify novel PLC modulators. Potent and selective modulators of PLCs will ultimately be useful for dissecting the roles of PLCs in cellular processes, as well as provide lead compounds for the development of drugs to treat diseases arising from aberrant phospholipase activity.     

Dynamics and allostery of the ionotropic glutamate receptors and the ligand binding domain

The dynamics of the ligand‐binding domain (LBD) and the intact ionotropic glutamate receptor (iGluR) were studied using Gaussian Network Model (GNM) analysis. The dynamics of LBDs with various allosteric modulators is compared using a novel method of multiple alignment of GNM modes of motion. The analysis reveals that allosteric effectors change the dynamics of amino acids at the upper lobe interface of the LBD dimer as well as at the hinge region between the upper‐ and lower‐ lobes. For the intact glutamate receptor the analysis show that the clamshell‐like movement of the LBD upper and lower lobes is coupled to the bending of the trans‐membrane domain (TMD) helices which may open the channel pore. The results offer a new insight on the mechanism of action of allosteric modulators on the iGluR and support the notion of TMD helices bending as a possible mechanism for channel opening. In addition, the study validates the methodology of multiple GNM modes alignment as a useful tool to study allosteric effect and its relation to proteins dynamics. Proteins 2016; 84:267–277. © 2015 Wiley Periodicals, Inc.     

Identification of Hsp70 modulators through modeling of the substrate binding domain

The design, synthesis and preliminary activity of small molecular weight modulators of the heat shock protein 70 (Hsp70) are described. The compounds provide a starting point for the synthesis of novel tools to decipher Hsp70 biology.     

Purine derivatives as potent γ-secretase modulators

The development of a novel series of purines as γ-secretase modulators for potential use in the treatment of Alzheimer’s disease is disclosed herein. Optimization of a previously disclosed pyrimidine series afforded a series of potent purine-based γ-secretase modulators with 300- to 2000-fold in vitro selectivity over inhibition of Notch cleavage and that selectively reduces Αβ42 in an APP-YAC transgenic mouse model.     

Chemical and functional diversity of small molecule ligands for RNA

Functional RNAs such as ribosomal RNA and structured domains of mRNA are targets for small molecule ligands that can act as modulators of the RNA biological activity. Natural ligands for RNA display a bewildering structural and chemical complexity that has yet to be matched by synthetic RNA binders. Comparison of natural and artificial ligands for RNA may help to direct future approaches to design and synthesize potent novel scaffolds for specific recognition of RNA targets.     

Iminoheterocycles as γ-secretase modulators

The synthesis of a novel series of iminoheterocycles and their structure–activity relationship (SAR) as modulators of γ-secretase activity will be detailed. Encouraging SAR generated from a monocyclic core led to a structurally unique bicyclic core. Selected compounds exhibit good potency as γ-secretase modulators, excellent rat pharmacokinetics, and lowering of Aβ₄₂ levels in various in vivo models.     

A high-content biosensor-based screen identifies cell-permeable activators and inhibitors of EGFR function: implications in drug discovery

Early success of kinase inhibitors has validated their use as drugs. However, discovery efforts have also suffered from high attrition rates due to lack of cellular activity. We reasoned that screening for such candidates in live cells would identify novel cell-permeable modulators for development. For this purpose, we have used our recently optimized epidermal growth factor receptor (EGFR) biosensor assay to screen for modulators of EGFR activity. Here, we report on its validation under high-throughput screening (HTS) conditions displaying a signal-to-noise ratio of 21 and a Z' value of 0.56-attributes of a robust cell-based assay. We performed a pilot screen against a library of 6912 compounds demonstrating good reproducibility and identifying 82 inhibitors and 66 activators with initial hit rates of 1.2% and 0.95%, respectively. Follow-up dose-response studies revealed that 12 of the 13 known EGFR inhibitors in the library were confirmed as hits. ZM-306416, a vascular endothelial growth factor receptor (VEGFR) antagonist, was identified as a potent inhibitor of EGFR function. Flurandrenolide, beclomethasone, and ebastine were confirmed as activators of EGFR function. Taken together, our results validate this novel approach and demonstrate its utility in the discovery of novel kinase modulators with potential use in the clinic.     

Development of inhibitors in the ubiquitination cascade

The ubiquitin proteasome system (UPS) is essential in regulating myriad aspects of protein functions. It is therefore a fundamentally important regulatory mechanism that impacts most if not all aspects of cellular processes. Indeed, malfunction of UPS components is implicated in human diseases such as neurodegenerative and immunological disorders and many cancers. The success of proteasome inhibitors in cancer therapy suggests that modulating enzymes in the ubiquitination cascade would be clinically important for therapeutic benefits. In this review, we summarize advances in developing inhibitors of a variety of UPS components. In particular, we highlight recent work done on the protein engineering of ubiquitin as modulators of the UPS, a novel approach that may shed light on innovative drug discovery in the future.     

Following autophagy step by step

Autophagy is an evolutionarily conserved lysosomal degradation route for soluble components of the cytosol and organelles. There is great interest in identifying compounds that modulate autophagy because they may have applications in the treatment of major diseases including cancer and neurodegenerative disease. Hundeshagen and colleagues describe this month in BMC Biology a screening assay based on flow cytometry that makes it possible to track distinct steps in the autophagic process and thereby identify novel modulators of autophagy.     

A new generation of progesterone receptor modulators

Progesterone receptor (PR) modulators have evolved both structurally and mechanistically over the past half-century. Classical steroidal PR agonists continue to play an important role in women's health such as in oral contraception and post-menopausal hormone therapy whereas steroid-based PR antagonists and selective PR modulators are being evaluated clinically in a wide range of gynecologic conditions. This review will focus primarily on the newer generation of PR modulators derived from structurally unique chemical scaffolds. For example, tanaproget (TNPR) is described as a non-steroidal PR agonist with high affinity and selectivity for the PR that is significantly more potent than many of its steroidal counterparts in a variety of pre-clinical efficacy models. Similarly, we present numerous examples of unique non-steroidal PR antagonists in various stages of characterization and development. A basic understanding of the structural determinants for high affinity binding of these new PR modulators to the PR ligand-binding domain (LBD) is also discussed. Finally, as the biology of the PR becomes further defined, we speculate on the future development of novel PR modulators.     

Optimization study towards more potent thiazolidine-2,4-dione IKK-β modulator: Synthesis,biological evaluation and in silico docking simulation

Inhibition of IKK-β (inhibitor of nuclear factor kappa-B kinase subunit beta) has been broadly documented as a promising approach for treatment of acute and chronic inflammatory diseases, cancer, and autoimmune diseases. Recently, we have identified a novel class of thiazolidine-2,4-diones as structurally novel modulators for IKK-β. Herein, we report a hit optimization study via analog synthesis strategy aiming to acquire more potent derivative(s), probe the structure activity relationship (SAR), and get reasonable explanations for the elicited IKK-β inhibitory activities though an in silico docking simulation study. Accordingly, a new series of eighteen thiazolidine-2,4-dione derivatives was rationally designed, synthesized, identified with different spectroscopic techniques and biologically evaluated as noteworthy IKK-β potential modulators. Successfully, new IKK-β potent modulators were obtained, including the most potent analog up-to-date 7m with IC₅₀ value of 260 nM. A detailed structure activity relationship (SAR) was discussed and a mechanistic study for 7m was carried out indicating its irreversible inhibition mode with IKK-β (K_inact value = 0.01 (min⁻¹). Furthermore, the conducted in silico simulation study provided new insights for the binding modes of this novel class of modulators with IKK-β.