More then 40,000 transcripts including novel and noncoding transcripts in mouse embryonic stem cells

To study the transcriptome of embryonic stem cells,we used a new gene expression profiling meethod which can measure the expression levels of unknown and rarely expressed transcripts precisely.We detected a total of 33,136 signal peaks representing transcripts in E14 mouse embryonic stem cells.Subsequent random cloning of the peaks suggests that mouse embryonic stem cells express at least 40,000 transcripts,of which about 2,000 are still unknown.In addition,we identified 1,022 non-coding transcripts,several of which change depending on differentiation in gene expression.Our database provides a high-resolution expression profile of E14 cells and is applicable to other mouse ES cell analyses.It includes most transcription regulation-encoding genes and a significant number of unknown and non-coding transcripts

ERK signaling controls blastema cell differentiation during planarian regeneration.

The robust regenerative ability of planarians depends on a population of somatic stem cells called neoblasts, which are the only mitotic cells in adults and are responsible for blastema formation after amputation. The molecular mechanism underlying neoblast differentiation associated with blastema formation remains unknown. Here, using the planarian Dugesia japonica we found that DjmkpA, a planarian mitogen-activated protein kinase (MAPK) phosphatase-related gene, was specifically expressed in blastema cells in response to increased extracellular signal-related kinase (ERK) activity. Pharmacological and genetic [RNA interference (RNAi)] approaches provided evidence that ERK activity was required for blastema cells to exit the proliferative state and undergo differentiation. By contrast, DjmkpA RNAi induced an increased level of ERK activity and rescued the differentiation defect of blastema cells caused by pharmacological reduction of ERK activity. These observations suggest that ERK signaling plays an instructive role in the cell fate decisions of blastema cells regarding whether to differentiate or not, by inducing DjmkpA as a negative regulator of ERK signaling during planarian regeneration