GATA6 phosphorylation by Erk1/2 propels exit from pluripotency and commitment to primitive endoderm

Abstract

The transcription factor GATA6 and the Fgf/Ras/MAPK signaling pathway are essential for the development of the primitive endoderm (PrE), one of the two lineages derived from the pluripotent inner cell mass (ICM) of mammalian blastocysts. A mutant mouse line in which Gata6-coding exons are replaced with H2BGFP (histone H2B Green Fluorescence Protein fusion protein) was developed to monitor Gata6 promoter activity. In the Gata6-H2BGFP heterozygous blastocysts, the ICM cells that initially had uniform GFP fluorescence signal at E3.5 diverged into two populations by the 64-cell stage, either as the GFP-high PrE or the GFP-low epiblasts (Epi). However in the GATA6-null blastocysts, the originally moderate GFP expression subsided in all ICM cells, indicating that the GATA6 protein is required to maintain its own promoter activity during PrE linage commitment. In embryonic stem cells, expressed GATA6 was shown to bind and activate the Gata6 promoter in PrE differentiation. Mutations of a conserved serine residue (S264) for Erk1/2 phosphorylation in GATA6 protein drastically impacted its ability to activate its own promoter. We conclude that phosphorylation of GATA6 by Erk1/2 compels exit from pluripotent state, and the phosphorylation propels a GATA6 positive feedback regulatory circuit to compel PrE differentiation. Our findings resolve the longstanding question on the dual requirements of GATA6 and Ras/MAPK pathway for PrE commitment of the pluripotent ICM.

Embryo gene expression in pig pregnancy

“…However, in porcine and mouse ICM, other transcription factors related to pluripotency such as GATA6 have been detected (Kuijk et al, ; Meng et al, ; Schrode, Saiz, Talia, & Hadjantonakis, ).. Nevertheless, Hall () indicate a possible entry of the embryo at rest due to the lack of genes expressed in the ICM, while during the same stage, the epiblast expresses several genes, such as SMAD (1, 2, 3, 4 and 5) or BMP4 , demonstrates higher pluripotent activity in porcine epiblast than in ICM, which exhibits a very premature pluripotency (Hall & Hyttel, ; Hall et al, ; Kuijk et al, ; Wolf, Serup, & Hyttel, ).…”

Manipulating the Mediator complex to induce naïve pluripotency

“…Specification of the PE is highly sensitive to MEK inhibition [ [98] , [99] , [100] ]. The phosphorylation of the transcription factor GATA6 by MEK has been recently shown to be a key event in the determination of the PE [ 101 ]. Since CDK8/19i does not affect the kinase activity of MEK [ 10 ], it is possible that the presence of an active MEK/GATA6 circuit is sufficient to determine PE formation in the face of CDK8/19 inhibition.…”

Dynamic Conversion of Cell Sorting Patterns in Aggregates of Embryonic Stem Cells with Differential Adhesive Affinity

“…The beta1 integrin-deficient primitive endoderm cells segregate from rather than form a layer covering the epiblast in both embryos and embryoid bodies (Moore et al, 2014b). Deficiency in endoderm differentiation was found in both embryos and embryoid bodies of GATA6 (Cai et al, 2008;Bessonnard et al, 2014;Schrode et al, 2014;Meng et al, 2018), or Grb2 (Cheng et al, 1998;Chazaud et al, 2006;Wang et al, 2011) null genotypes. Pten is required for cavitation in both embryos and embryoid bodies (Meng et al, 2017).…”