Young-Kwon Choi

Inhibitory effect of progesterone during early embryonic development: Suppression of myocardial differentiation and calcium-related transcriptome by progesterone in mESCs: Progesterone disturb cardiac differentiation of mESCs through lower cytosolic Ca2+

Progesterone (PG) and its derivates are used in prevention of spontaneous miscarriage. However, some studies have reported that exposure to PG and its derivates during pregnancy can cause malformations and affect both blood pressure and the cardiovascular system. The effect of PG on cardiomyogenesis of mouse embryonic stem cells (mESCs) is not well known. Expression of Pgr mRNA showed an opposite pattern of beating-ratio during differentiation. PG treatment resulted in reduction of the beating ratio to 60.45±1.54% from 92.17±2.98% in normal differentiation, reduced transcripts of heart morphogenesis and Ca(2+) binding-related genes in the next generation sequencing data and significantly decreased expression levels of Ca(2+)/contraction-related genes including Ryr2, Calm2, Trpv2, and Mylk3, the intracellular Ca(2+) level, and the beating frequency. These results suggest that PG exerts inhibitory effects on differentiation of mESCs into functional cardiomyocytes.

Advanced developmental toxicity test method based on embryoid body’s area

Embryonic stem cell test (EST) evaluates the embryotoxic potential of substances and measures the half inhibition in viability of mouse embryonic stem cells (ESCs), fibroblasts (3T3 cells) and in cardiac differentiation of ESC. In this study, we suggest the developmental toxicity test method (termed EBT) applying area of embryoid bodies (EBs) instead of cardiac differentiation of EST. In the assessment of 21 substances, EB area was logarithmically decreased in dose-dependent manner. Decline in EB area resulted in decrease of beating ratio during differentiation of ESCs. In classification by the EBT-based prediction model reflecting decline in cell viability and EB area, toxicity for 21 chemicals showed 90.5% accuracy. In the results of next generation sequencing, reduction in EB area resulted from cell cycle arrest mediated by HDAC2 and CDKN2A. Conclusively, EBT is advanced and is a useful tool to assess and classify various embryotoxicants in a short time with less effort.

Immortalization of Porcine 11β-Hydroxysteroid Dehydrogenase Type 1-Transgenic Liver Cells Using SV40 Large T Antigen

Cortisol is a steroid hormone essential to the maintenance of homeostasis that is released in response to stress and low blood glucose concentration. Cortisol is converted from cortisone by 11β-hydroxysteroid dehydrogenase type 1 (HSD11B1). It has been reported that too much cortisol or overexpression of HSD11B1 induces obesity and the insulin resistance that accompanies metabolic syndrome in rodent adipose tissue. In our previous study, HSD11B1-transgenic (TG) fibroblasts were established, and a porcine model was generated by SCNT using those fibroblasts. Hepatocytes overexpressing HSD11B1 were obtained from livers of this porcine model and cultured in vitro. However, the primary hepatocytes were found to have a short life span or low proliferation rate. To overcome these problems, the SV40 large T antigen was transduced into primary HSD11B1-TG hepatocytes, and those cells were immortalized. Immortalized HSD11B1-TG hepatocytes showed restored morphology, more rapid proliferation rate, and more expression of HSD11B1 than primary hepatocytes. As well, these cells kept the hepatic characteristics such as gluconeogenic response to cortisone and increased expression of hepatic makers. The immortalized HSD11B1-TG hepatocytes may be useful for studying traits and potential therapeutic drugs for treatment of metabolic disorders induced by overexpression of HSD11B1.