Understanding the first steps in embryonic stem cell exit from the pluripotent state

CRISPR-Cas9-mediated knockout of the Prkdc in mouse embryonic stem cells leads to the modulation of the expression of pluripotency genes

Prkdc encodes for the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs) playing a key role in nonhomologous end joining pathway during DNA double-strand break repair and also influencing the homologous recombination (HR) repair system by phosphorylation of proteins involved in HR. In addition, Prkdc has other critical functions in biological processes, such as transcriptional regulation, telomere stability, apoptosis, and metabolism. DNA-PKcs upregulates during in vitro differentiation of mouse embryonic stem cells (mESCs). To address the potential role of Prkdc in mESCs pluripotency and in vitro differentiation into ectoderm, mesoderm, and endoderm germ layers under normal physiological conditions, a bi-allelic Prkdc-knockout cell line was generated in the present study by employing CRISPR/Cas9 system, and subsequently, its potential role in stemness and development was studied. The results of the study showed that the expression of pluripotency-associated genes, including Nanog and Sox-2 were overexpressed in the bi-allelic Prkdc-knockout cell line. Also, bi-allelic Prkdc-knockout cell line was shown to have typical mESCs cell morphology, cell cycle distribution, and alkaline phosphatase activity. Furthermore, the results of the study revealed that the expression of several germ layer markers is modulated in Prkdc-knockout lines. In conclusion, the findings of our study demonstrated the role of Prkdc during differentiation and development of ESCs.

Phenotypic Screening of Drug Library in Actively Differentiating Mouse Embryonic Stem Cells

Phenotypic screening enables the discovery of new drug leads with novel targets. ES cells differentiate into different lineages by successively making use of different subsets of the genome's possible macromolecular interactions. If a compound effectively targets just one of these interactions, it derails the developmental pathway to produce a phenotypical change. The OTRADI microsource spectrum library of 2000 approved drug components, natural products, and bioactive components was screened for compounds that can induce phenotypic changes in ES cell cultures at 10 µM after 3 days. Twenty-one compounds that induced specific morphologies also induced unique changes to an expression profile of a dozen markers of early embryonic development, indicating that each compound has derailed the molecular developmental process in a characteristic way. Phenotypic screens conducted with ES cultures differentiating along different lineages can be used to efficiently prescreen compounds able to regulate cell differentiation lineage.

Endothelial differentiation of adipose-derived mesenchymal stem cells is improved by epigenetic modifying drug BIX-01294

Chromatin remodeling plays an essential role in regulation of gene transcription. Consequently, targeted changes in chromatin may also augment pluripotency of somatic cells. The aim of the present study was to evaluate the effect of epigenetic drug BIX-01294 (BIX), a histone G9a inhibitor, on DNA methylation, expression of pluripotency genes POU5F1 (isoform a), NANOG, KLF4, and CMYC in mesenchymal stem cells, and the ability to increase their differentiation potential into endothelial cells (ECs). Human adipose-derived mesenchymal stem cells (AdMSCs) were isolated from abdominal adipose tissue. Cells were pre-treated with BIX for 48h and further differentiated in endothelial medium for 7 and 14 days. Global DNA methylation was determined by MethyLight application, expression of genes for pluripotency, endothelial and angiogenic markers by SYBRGreen-based real-time PCR, immunocytochemistry, and immunobloting. Following treatment with BIX, DNA methylation status of AdMSCs was significantly reduced by 53% (p=0.008), the expression of POU5F1 and NANOG was increased by 2.2-fold (p=0.016) and 1.5-fold (p<0.001), respectively. Furthermore, BIX pre-treatment improved the differentiation capacity of AdMSCs into ECs and significantly increased expression of several endothelial markers and factors involved in blood vessel formation: VCAM-1, PECAM-1, von Willebrand factor, VEGFR-2, PDGF, and ANG-1 in comparison with AdMSCs without BIX pre-treatment. In the present study we demonstrate that epigenetic modifying drug BIX-01294 is able to increase the ability of AdMSCs to differentiate into ECs engaging DNA and histone methylation. Hence, BIX-01294 might serve as a simple tool to increase the differentiation potential of AdMSCs.