Activin A-derived human embryonic stem cells show increased competence to differentiate into primordial germ cell-like cells.

Protocols for specifying human primordial germ cell-like cells (hPGCLCs) from human embryonic stem cells (hESCs) remain hindered by differences between hESC lines, their derivation methods, and maintenance culture conditions. This poses significant challenges for establishing reproducible in vitro models of human gametogenesis. Here, we investigated the influence of activin A (ActA) during derivation and maintenance on the propensity of hESCs to differentiate into PGCLCs. We show that continuous ActA supplementation during hESC derivation (from blastocyst until the formation of the post-inner cell mass intermediate [PICMI]) and supplementation (from the first passage of the PICMI onwards) is beneficial to differentiate hESCs to PGCLCs subsequently. Moreover, comparing isogenic primed and naïve states prior to differentiation, we showed that conversion of hESCs to the 4i-state improves differentiation to (TNAP [tissue nonspecific alkaline phosphatase]+/PDPN [podoplanin]+) PGCLCs. Those PGCLCs expressed several germ cell markers, including TFAP2C (transcription factor AP-2 gamma), SOX17 (SRY-box transcription factor 17), and NANOS3 (nanos C2HC-type zinc finger 3), and markers associated with germ cell migration, CXCR4 (C-X-C motif chemokine receptor 4), LAMA4 (laminin subunit alpha 4), ITGA6 (integrin subunit alpha 6), and CDH4 (cadherin 4), suggesting that the large numbers of PGCLCs obtained may be suitable to differentiate further into more mature germ cells. Finally, hESCs derived in the presence of ActA showed higher competence to differentiate to hPGCLC, in particular if transiently converted to the 4i-state. Our work provides insights into the differences in differentiation propensity of hESCs and delivers an optimized protocol to support efficient human germ cell derivation.

Effect of 17ß-estradiol and flavonoids on the regulation of expression of newly identified oestrogen responsive genes in a rat raphe nuclei-derived cell line.

Due to the health risks attributed to perimenopausal hormone therapy, phytoestrogens such as flavonoids are receiving widespread attention to help alleviate menopausal symptoms, including hormone-driven mood disorders. Based on our previous reporter gene study regarding their transactivational activity in raphe nuclei cells from a brain region involved in regulation of mood disturbances, we herein study their effects on the regulation of expression of 17ß-estradiol (E2)-regulated genes. DNA microarray was used to globally assess E2-induced gene expression in RNDA cells, a rat raphe nuclei-derived cellular model expressing oestrogen receptor ß. Out of 212 regulated genes, six were selected for verification and as endpoints for the effect of flavonoids on the regulation of mRNA expression in proliferating as well as differentiating RNDA cells. Under proliferative conditions, E2 up-regulated mRNA expression of Cml-5, Sox-18 and Krt-19. Similar effects were observed in response to 8-prenylnaringenin (8-PN), genistein (GEN), daidzein (DAI) and equol (EQ). In line with E2, mRNA expression of Nefm and Zdhhc-2 was down-regulated following 8-PN, GEN, DAI, EQ and naringenin treatment. No regulation was observed on Slc6a4 mRNA expression in response to E2 or the flavonoids in proliferating RNDA cells. When cells were shifted to conditions promoting differentiation, changes in cell morphology, in mRNA expression levels and in responsiveness towards E2 and the tested flavonoids were noticed. These expression studies additionally highlighted some of the genes as markers for RNDA cellular differentiation. RNDA cells should prove useful to elucidate molecular and cellular mechanisms of exogenous oestrogen receptor ligands with neural cell populations.

TAp63 is important for cardiac differentiation of embryonic stem cells and heart development.

p63, a member of the p53 family, is essential for skin morphogenesis and epithelial stem cell maintenance. Here, we report an unexpected role of TAp63 in cardiogenesis. p63 null mice exhibit severe defects in embryonic cardiac development, including dilation of both ventricles, a defect in trabeculation and abnormal septation. This was accompanied by myofibrillar disarray, mitochondrial disorganization, and reduction in spontaneous calcium spikes. By the use of embryonic stem cells (ESCs), we show that TAp63 deficiency prevents expression of pivotal cardiac genes and production of cardiomyocytes. TAp63 is expressed by endodermal cells. Coculture of p63-knockdown ESCs with wild-type ESCs, supplementation with Activin A, or overexpression of GATA-6 rescue cardiogenesis. Therefore, TAp63 acts in a non-cell-autonomous manner by modulating expression of endodermal factors. Our findings uncover a critical role for p63 in cardiogenesis that could be related to human heart disease.

Conserved regulatory motifs at phenylethanolamine N-methyltransferase (PNMT) are disrupted by common functional genetic variation: an integrated computational/experimental approach.

The adrenomedullary hormone epinephrine transduces environmental stressors into cardiovascular events (tachycardia and hypertension). Although the epinephrine biosynthetic enzyme PNMT genetic locus displays both linkage and association to such traits, genetic variation underlying these quantitative phenotypes is not established. Using an integrated suite of computational and experimental approaches, we elucidate a functional mechanism for common (minor allele frequencies > 30%) genetic variants at PNMT. Transcription factor binding motif prediction on mammalian PNMT promoter alignments identified two variant regulatory motifs, SP1 and EGR1, disrupted by G-367A (rs3764351), and SOX17 motif created by G-161A (rs876493). Electrophoretic mobility shifts of approximately 30-bp oligonucleotides containing ancestral versus variant alleles validated the computational hypothesis. Queried against chromaffin cell nuclear protein extracts, only the G-367 and -161A alleles shifted. Specific antibodies applied in electrophoretic gel shift experiments confirmed binding of SP1 and EGR1 to G-367 and SOX17 to -161A. The in vitro allele-specific binding was verified in cella through promoter reporter assays: lower activity for -367A haplotypes cotransfected by SP1 (p = 0.002) and EGR1 (p = 0.034); and enhanced inhibition of -161A haplotypes (p = 0.0003) cotransfected with SP1 + SOX17. Finally, we probed cis/trans regulation with endogenous factors by chromatin immunoprecipitation using SP1/EGR1/SOX17 antibodies. We describe the systematic application of complementary computational and experimental techniques to detect and document functional genetic variation in a trait-associated regulatory region. The results provide insight into cis and trans transcriptional mechanisms whereby common variation at PNMT can give rise to quantitative changes in human physiological and disease traits. Thus, PNMT variants in cis may interact with nuclear factors in trans to govern adrenergic activity.