Multimodal action of KRP203 on phosphoinositide kinases in vitro and in cells

Increased phosphoinositide signaling is commonly associated with cancers. While "one-drug one-target" has been a major drug discovery strategy for cancer therapy, a "one-drug multi-targets" approach for phosphoinositide enzymes has the potential to offer a new therapeutic approach. In this study, we sought a new way to target phosphoinositides metabolism. Using a high-throughput phosphatidylinositol 5-phosphate 4-kinase-alpha (PI5P4Kα) assay, we have identified that the immunosuppressor KRP203/Mocravimod induces a significant perturbation in phosphoinositide metabolism in U87MG glioblastoma cells. Despite high sequence similarity of PI5P4K and PI4K isozymes, in vitro kinase assays showed that KRP203 activates some (e.g., PI5P4Kα, PI4KIIβ) while inhibiting other phosphoinositide kinases (e.g., PI5P4Kβ, γ, PI4KIIα, class I PI3K-p110α, δ, γ). Furthermore, KRP203 enhances PI3P5K/PIKFYVE's substrate selectivity for phosphatidylinositol (PI) while preserving its selectivity for PI(3)P. At cellular levels, 3 h of KRP203 treatment induces a prominent increase of PI(3)P and moderate increase of PI(5)P, PI(3, 5)P₂, and PI(3, 4, 5)P₃ levels in U87MG cells. Collectively, the finding of multimodal activity of KRP203 towards multi-phosphoinositide kinases may open a novel basis to modulate cellular processes, potentially leading to more effective treatments for diseases associated with phosphoinositide signaling pathways

A Homogeneous, High-Throughput Assay for Phosphatidylinositol 5-Phosphate 4-Kinase with a Novel, Rapid Substrate Preparation

Phosphoinositide kinases regulate diverse cellular functions and are important targets for therapeutic development for diseases, such as diabetes and cancer. Preparation of the lipid substrate is crucial for the development of a robust and miniaturizable lipid kinase assay. Enzymatic assays for phosphoinositide kinases often use lipid substrates prepared from lyophilized lipid preparations by sonication, which result in variability in the liposome size from preparation to preparation. Herein, we report a homogeneous 1536-well luciferase-coupled bioluminescence assay for PI5P4Kα. The substrate preparation is novel and allows the rapid production of a DMSO-containing substrate solution without the need for lengthy liposome preparation protocols, thus enabling the scale-up of this traditionally difficult type of assay. The Z’-factor value was greater than 0.7 for the PI5P4Kα assay, indicating its suitability for high-throughput screening applications. Tyrphostin AG-82 had been identified as an inhibitor of PI5P4Kα by assessing the degree of phospho transfer of γ-$^{32}$P-ATP to PI5P; its inhibitory activity against PI5P4Kα was confirmed in the present miniaturized assay. From a pilot screen of a library of bioactive compounds, another tyrphostin, I-OMe tyrphostin AG-538 (I-OMe-AG-538), was identified as an ATP-competitive inhibitor of PI5P4Kα with an IC$_{50}$ of 1 µM, affirming the suitability of the assay for inhibitor discovery campaigns. This homogeneous assay may apply to other lipid kinases and should help in the identification of leads for this class of enzymes by enabling high-throughput screening efforts

The Role of Nitrates in the Management of Stable Ischemic Heart Disease: A Review of the Current Evidence and Guidelines

Coronary artery disease is the leading cause of mortality in the United States and can result in significant morbidity. In particular, stable ischemic heart disease (SIHD) is a condition that affects nearly 9 million individuals in the United States alone, with substantial annual health care costs related to recurrent medical visits and chronic disease management. Nitrates form a cornerstone of SIHD management by reducing myocardial oxygen consumption and increasing exercise capacity by several mechanisms, including increasing epicardial blood flow through vasodilation and decreased vascular resistance, blunting coronary steal, and reducing preload. Yet the role of nitrates may be underappreciated in clinical practice and their utilization may be limited due to concerns of tolerance to treatment, a lack of randomized data validating their ability to prevent adverse cardiovascular events, and the pervasive use of percutaneous interventions without robust attempts at implementing optimal medical therapy. In this review, we discuss both the recent ACC/AHA/ACP/AATS/PCNA/SCAI/STS and European Society of Cardiology guidelines, with a particular focus on indications, contraindications, and future directions of nitrate therapy in SIHD

<i>De Novo</i> Synthesis of l-Colitose and l-Rhodinose Building Blocks

A divergent, practical, and efficient <i>de novo</i> synthesis of fully functionalized l-colitose (3,6-dideoxy-l-galactose), 2-<i>epi</i>-colitose (3,6-dideoxy-l-talose), and l-rhodinose (2,3,6-trideoxy-l-galactose) building blocks has been achieved using inexpensive, commercially available (<i>S</i>)-ethyl lactate as the starting material. The routes center around a diastereoselective Cram-chelated allylation that provides a common homoallylic alcohol intermediate. Oxidation of this common intermediate finally resulted in the synthesis of the three monosaccharide building blocks