Establishment of a developmental toxicity assay based on human iPSC reporter to detect FGF signal disruption

Fungal Depsidones Stimulate AKT-Dependent Glucose Uptake in 3T3-L1 Adipocytes

Enhanced glucose uptake in insulin-sensitive tissues is one of the therapeutic strategies to ameliorate hyperglycemia and maintain glucose homeostasis in type 2 diabetes. This study disclosed the role of fungal depsidones in glucose uptake and the underlying mechanism in 3T3-L1 adipocytes. Depsidones, including nidulin, nornidulin, and unguinol, isolated from Aspergillus unguis, stimulate glucose uptake in adipocytes. Compared to the others, nidulin exhibited an upward trend in glucose uptake. The effect of nidulin was found to be dose- and time-dependent. Nidulin also enhanced insulin- and metformin-stimulated glucose uptake. Upregulation of GLUT4 expression and AKT and AMPK phosphorylation were observed with nidulin treatment. Blockage of AKT, but not AMPK, phosphorylation was largely accompanied by diminished glucose uptake. In agreement, nidulin triggered the translocation of GLUT4 to the plasma membrane. Importantly, nidulin elevated glucose uptake associated with increased AKT phosphorylation in insulin-resistant adipocytes. Taken together, nidulin could stimulate glucose uptake mainly through AKT-dependent GLUT4 translocation, serving as a seed compound in drug discovery for type 2 diabetes.

Human Pluripotent Stem Cell-Based Assays to Predict Developmental Toxicity

Human beings are continuously exposed to various toxic substances throughout their lives, which affect their reproductive health and eventually the offspring they give birth to. Mainly, these toxins damage the heart and neurological development of the newborn, but most recently, they have begun to affect the musculoskeletal system as well. These toxins are usually present in food, pharmaceuticals, cosmetics, or even the polluted air that people breathe; as a result, the prevalence of birth defects is steadily rising. For this reason, it becomes a necessity to deploy a new set of assays to test for such toxins in industries to decrease the occurrence of developmental toxicity. These assays are exceedingly expensive when carried out conventionally using animal models or cells from such sources and have a lower predictive value due to the vast variation between animals and humans. To overcome such major problems, human pluripotent stem cells are now frequently used for these assays. These cells are easily available, are quickly generated from somatic cells (induce pluripotent stem cells), can be of human origin without harming people, and eliminate animal harm, which makes them the top choice of scientists for carrying out any in vitro developmental toxicity assays.This chapter, therefore, provides an overview of several steps that can be used to predict a compound's developmental toxicity by utilizing human pluripotent stem cells. Here, the easiest and most effective procedure has been outlined that can screen many compounds simultaneously.

Luciferase assay system to monitor fibroblast growth factor signal disruption in human iPSCs

We describe a protocol for a live-cell luciferase assay system for continuously monitoring fibroblast growth factor (FGF) signal disruption in human-induced pluripotent stem cells (iPSCs). Signal disrupting effects of chemicals are used as an indicator to evaluate toxicity. The assay is reliably predictive of the effects of limb malformation chemicals (AUC = 0.93). The current approach is limited to FGF signal disruption, and combinations with other types of signaling will be required to detect the effects of different toxicants. For complete details on the use and execution of this protocol, please refer to Kanno et al. (2022a).

Integrated fibroblast growth factor signal disruptions in human iPS cells for prediction of teratogenic toxicity of chemicals

The number of man-made chemicals has increased rapidly in recent decades, with certain chemicals potentially causing malformations in fetuses. Although the toxicities of chemicals have been tested in animals, chemicals that are not teratogenic in rodents can cause severe malformations in humans, owing to the differences in the susceptibility to the teratogenicity of chemicals among species. One possible cause of such species differences, other than pharmacokinetics, could be the difference in sensitivity to such chemicals at the cellular level. Therefore, a human cell-based high-throughput assay system is needed for detecting potential teratogenic chemicals. In this study, we proposed a signal reporter assay using human induced pluripotent stem cells (iPSCs). Because developmental processes are governed by highly intricate and precisely programmed signaling pathways, external chemical-induced disruption of these pathways often triggers developmental toxicities. The reporter assay using hiPSCs was used to detect changes in the fibroblast growth factor (FGF) signaling pathway, a pathway essential for limb morphogenesis. The method was based on monitoring and time-accumulation of the signal disruption over time, rather than the classical endpoint detection of the signal disruption. This approach was useful for detecting signal disruptions caused by the malformation chemicals listed in the ICH S5 guideline, including thalidomide. The human iPSC-based signal disruption assay could be a promising tool for the initial screening of developmental toxicants.