1,5-Disubstituted benzimidazoles that direct cardiomyocyte differentiation from mouse embryonic stem cells

Generation of muscle progenitors from human-induced pluripotent stem cells

Background

Small molecules have a role in the differentiation of human-induced pluripotent stem cells (hiPSCs) into different cell linages. The aim of this study was to evaluate the differentiation of hiPSCs into cardiac or skeletal myogenic progenitors with a single small molecule.

Methods

hiPSCs were treated with three different small molecules such as Isoxazole-9, Danazol and Givinostat in serum-free medium for 7 days. Cell viability, qRT-PCR, western blots, and immunostaining were assessed after treatment of hiPSCs with small molecules.

Results

Higher hiPSC viability was observed in hiPSCs treated with Isoxazole-9 (25 µM), Danazol (25 µM) and Givinostat (150 nM) versus control (P < 0.05). Givinostat had dual effect by generating both skeletal and cardiac progenitor cells versus Isoxazole-9 and Danazol after 7 days. Givinostat treatment induced upregulation of skeletal myogenic genes and their protein expression levels on day 4 and further increased on day 8 (P < 0.05) versus control. Furthermore,positive stained cells for Pax3, Myf5, MyoD1, dystrophin, desmin, myogenin, and β-catenin at 1 month. Givinostat increased upregulation of cardiac gene expression levels versus control after day 4 (P < 0.05), with positive stained cells for Nkx2.5, GATA4, TnT, TnI, connexin 43 and α-sarcomeric actinin at 1 month.

Conclusions

Pretreatment of hiPSCs with Givinostat represents a viable strategy for producing both cardiac/skeletal myogenic progenitors in vitro for cell therapies against myocardial infarction and Duchenne muscular dystrophy.

Identification of the Benzoimidazole Compound as a Selective FLT3 Inhibitor by Cell-Based High-Throughput Screening of a Diversity Library

Internal tandem duplication in the FLT3 receptor tyrosine kinase (FLT3/ITD mutation) occurs in approximately 25% of acute myeloid leukemia (AML) patients. To specifically target this driver mutation in AML, we assessed and compared the cell-based cytotoxicity of a diversity library (10,000 compounds) against the normal cell line BaF3 and the isogenic leukemic cell line BaF3/ITD. A benzoimidazole scaffold-based compound (HP1142) was identified as the most selective compound against a series of murine and human leukemia cells with FLT3/ITD. Novel benzoimidazole compounds were further designed to improve the aqueous solubility of HP1142. The most potent compound, HP1328, demonstrated desirable pharmaceutical and pharmacokinetic properties. Treatment with HP1328 significantly reduced the leukemia burden and prolonged the survival of mice with FLT3/ITD leukemia. Our findings establish the specific activity of the benzoimidazole compound against FLT3/ITD leukemia and warrant further investigation in this subset of leukemia patients with poor prognosis.

Small Molecule Regulation of Stem Cells that Generate Bone, Chondrocyte, and Cardiac Cells

Embryonic stem cells (ESCs) are stem cells (SCs) that can self-renew and differentiate into a myriad of cell types. The process of developing stemness is determined by signaling molecules that drive stem cells to a specific lineage. For example, ESCs can differentiate into mature cells (e.g., cardiomyocytes) and mature cardiomyocytes can be characterized for cell beating, action potential, and ion channel function. A goal of this Perspective is to show how small molecules can be used to differentiate ESCs into cardiomyocytes and how this can reveal novel aspects of SC biology. This approach can also lead to the discovery of new molecules of use in cardiovascular disease. Human induced pluripotent stem cells (hiPSCs) afford the ability to produce unlimited numbers of normal human cells. The creation of patient-specific hiPSCs provides an opportunity to study cell models of human disease. The second goal is to show that small molecules can stimulate hiPSC commitment to cardiomyocytes. How iPSCs can be used in an approach to discover new molecules of use in cardiovascular disease will also be shown in this study. Adult SCs, including mesenchymal stem cells (MSCs), can likewise participate in self-renewal and multilineage differentiation. MSCs are capable of differentiating into osteoblasts, adipocytes or chondrocytes. A third goal of this Perspective is to describe differentiation of MSCs into chondrogenic and osteogenic lineages. Small molecules can stimulate MSCs to specific cell fate both in vitro and in vivo. In this Perspective, some recent examples of applying small molecules for osteogenic and chondrogenic cell fate determination are summarized. Underlying molecular mechanisms and signaling pathways involved are described. Small molecule-based modulation of stem cells shows insight into cell regulation and potential approaches to therapeutic strategies for MSC-related diseases.

The Disappearing Director: The Case of Directed N-Arylation via a Removable Hydroxyl Group

A facile and broadly applicable method for the regiospecific N-arylation of benzotriazoles is reported. Copper-mediated reactions of diverse 1-hydroxy-1H-benzotriazoles with aryl boronic acids lead to 1-aryl-1H-benzotriazole 3-oxides. A N1-OH → N3 prototropy in the 1-hydroxy-1H-benzotriazoles is plausibly the underlying basis, where the tautomer is captured by the boronic acid, leading to C-N (not C-O) bond formation. Because the N-O bond in amine N-oxides and 1-hydroxy-1H-benzotriazoles can be easily reduced by diboron reagents such as (pinB)2 and B2(OH)4, exposure of the 1-aryl-1H-benzotriazole 3-oxides to B2(OH)4 then leads to facile reduction of the N-O bond resulting in diverse, regiospecifically-arylated benzotriazoles. Thus, the N-hydroxyl group in 1-hydroxy-1H-benzotriazoles acts as a disposable arylation director.

Efficient synthetic route to aromatic secondary amines via Pd/RuPhos/TBAB-catalyzed cross coupling

Herein, C–N cross coupling methodology was developed for the synthesis of a diverse range of nitro-substituted secondary amines.

Therapeutic evolution of benzimidazole derivatives in the last quinquennial period

Benzimidazole, a fused heterocycle bearing benzene and imidazole has gained considerable attention in the field of contemporary medicinal chemistry. The moiety is of substantial importance because of its wide array of pharmacological activities. This nitrogen containing heterocycle is a part of a number of therapeutically used agents. Moreover, a number of patents concerning this moiety in the last few years further highlight its worth. The present review covers the recent work published by scientists across the globe during last five years.

Peroxiredoxin-2 nitrosylation facilitates cardiomyogenesis of mouse embryonic stem cells via XBP-1s/PI3K pathway

Protein nitrosylation is a ubiquitous post-translational modification in almost all biological systems. However, its function on stem cell biology is so far incompletely understood. Here, we demonstrated that peroxiredoxin 2 (Prdx-2) nitrosylation was involved in cardiomyocyte differentiation of mouse embryonic stem (ES) cells induced by S-nitrosoglutathione (GSNO). We found that temporary GSNO exposure could promote ES cell-derived cardiomyogenesis. Using a stable isotope labeling by amino acids in cell culture (SILAC)-based proteomics approach, coupled with biotin switch technique, a total of 104 nitrosylated proteins were identified. Specifically, one of the antioxidant enzymes, Prdx-2, was abundantly nitrosylated and temporarily reduced in antioxidant activity, causing transient endogenous hydrogen peroxide (H2O2) accumulation and subsequent X-box binding protein-1s/phosphatidylinositol 3-kinase pathway activation. The present study reveals the mechanism in which GSNO favors cardiomyocyte differentiation. Prdx-2 nitrosylation could be a potent strategy to affect the pluripotent stem cell-derived cardiomyogenesis.