Differentiation of embryonic stem cells 1 (Dies1) is a component of bone morphogenetic protein 4 (BMP4) signaling pathway required for proper differentiation of mouse embryonic stem cells

摘要

Embryonic stem cells (ESCs) are pluripotent cells able to growindefinitely in culture and to differentiate into all cell types ofembryos upon specific stimuli. Molecular mechanisms controllingthe unique characteristics of ESCs are still largely unknown.We identified Dies1 (Differentiation of ESCs 1), an unpublishedgene, that encodes a type I membrane protein. ESCs stablytransfected with Dies1 small hairpin RNAs failed to properlydifferentiate toward neural and cardiac cell fate upon appropriatestimuli and continued to express markers of undifferentiatedcells, such as the membrane-associated alkaline phosphatase,and transcription factors, like Oct3/4 and Nanog, whengrown under conditions promoting differentiation. Our resultsdemonstrated that Dies1 is required for BMP4/Smad1 signalingcascade; in undifferentiated ESCs Dies1 knockdown did notaffect the expression of leukemia inhibitory factor downstreamtargets, whereas it resulted in a strong decrease of BMP4 signaling, as demonstrated by the decrease of Id1, -2, and -3 mRNAs,the decreased activity of Id1 gene promoter, and the reducedphospho-Smad1 levels. Dies1 knockdown had no effect inmurine ESCs when the expression of the BMP4 receptor Alk3was suppressed. The phenotype induced by Dies1 suppressionin ESCs is due to the indirect activation of the Nodal/Activinpathway, which is a consequence of the BMP4 pathway inhibition and is sufficient to support the mESC undifferentiated state in the absence of leukemia inhibitory factor.