Yamanaka factors critically regulate the developmental signaling network in mouse embryonic stem cells

Yamanaka factors （Oct3/4, Sox2, Klf4, c-Myc） are highly expressed in embryonic stem （ES） cells, and their overexpression can induce pluripotency in both mouse and human somatic cells, indicating that these factors regulate the developmental signaling network necessary for ES cell pluripotency. However, systemic analysis of the signaling pathways regulated by Yamanaka factors has not yet been fully described. In this study, we identified the target promoters of endogenous Yamanaka factors on a whole genome scale using ChIP （chromatin immunoprecipitation）- on-chip in El4.1 mouse ES cells, and we found that these four factors co-occupied 58 promoters. Interestingly, when Oct4 and Sox2 were analyzed as core factors, Klf4 functioned to enhance the core factors for development regulation, whereas c-Myc seemed to play a distinct role in regulating metabolism. The pathway analysis revealed that Yamanaka factors collectively regulate a developmental signaling network composed of 16 developmental signaling pathways, nine of which represent earlier unknown pathways in ES cells, including apoptosis and cellcycle pathways. We further analyzed data from a recent study examining Yamanaka factors in mouse ES ceils. Interestingly, this analysis also revealed 16 developmental signaling pathways, of which 14 pathways overlap with the ones revealed by this study, despite that the target genes and the signaling pathways regulated by each individual Yamanaka factor differ significantly between these two datasets. We suggest that Yamanaka factors critically regulate a developmental signaling network composed of approximately a dozen crucial developmental signaling pathways to maintain the pluripotency of ES cells and probably also to induce pluripotent stem cells.

Rapid Quantification of Chinese Medicine Zuo Jin Pill via RRLC

A rapid method based on rapid resolution liquid chromatography（RRLC） coupled with a diode array detector（DAD） was developed for the simultaneous determination of six major constituents（magnoflorine,jatrorrhizine,coptisine,palmatine,berberine and evodiamine） in traditional Chinese medicine（TCM） Zuo Jin Pill（ZJP）.The satisfactory chromatographic separation was carried on an Eclipse Plus C18 column（1.8 μm i.d.,150 mm×4.6 mm） by linear gradient elution with a mobile phase of acetonitrile-acetate buffer.All the calibration curves show good linearity（r2 0.9998）.The detection limits and quantification limits ranged in 1.4―12 ng and 4.8―30 ng,respectively.The intra-and inter-day precisions were less than 0.63% with accuracies 98.60%―100.78%,and the recoveries were from 99.45% to 100.46%.Furthermore,hierarchical cluster analysis（HCA） was used to evaluate the variation of the herbal prescription.The results demonstrate that this analytical method is simple,sensitive and reliable for rapidly analyzing six major bioactive compounds in ZJPs and is helpful to comprehensively evaluating the quality of this TCM.