Stk40 links the pluripotency factor Oct4 to the Erk/MAPK pathway and controls extraembryonic endoderm differentiation

Abstract

Self-renewal and differentiation of embryonic stem cells (ESCs) are controlled by intracellular transcriptional factors and extracellular factor-activated signaling pathways. Transcription factor Oct4 is a key player maintaining ESCs in an undifferentiated state, whereas the Erk/MAPK pathway is known to be important for ESC differentiation. However, the manner in which intracellular pluripotency factors modulate extracellular factor-activated signaling pathways in ESCs is not well understood. Here, we report identification of a target gene of Oct4, serine/threonine kinase 40 (Stk40), which is able to activate the Erk/MAPK pathway and induce extraembryonicendoderm (ExEn) differentiation in mouse ESCs. Interestingly, cells overexpressing Stk40 exclusively contribute to the ExEn layer of chimeric embryos when injected into host blastocysts. In contrast, deletion of Stk40 in ESCs markedly reduces ExEn differentiation in vitro. Mechanistically, Stk40 interacts with Rcn2, which also activates Erk1/2 to induce ExEn specification in mouse ESCs. Moreover, Rcn2 proteins are specifically located in the cytoplasm of the ExEn layer of early mouse embryos. Importantly, knockdown of Rcn2 blocks Stk40-activated Erk1/2 and ESC differentiation. Therefore, our study establishes a link between the pluripotency factor Oct4 and the Erk/MAPK signaling pathway, and it uncovers cooperating signals in the Erk/ MAPK activation that control ExEn differentiation.embryonic stem cells | Rcn2 | Ras | Gata6

Stk40 represses adipogenesis through translational control of CCAAT/enhancer-binding proteins

“…Stk40, a putative serine/threonine kinase, was originally identified as an activator of the Erk1/2 (also known as MAPK3 and MAPK1, respectively) signaling required for primitive endoderm differentiation from mouse embryonic stem cells, and was later found to be important for mouse fetal lung maturation (Li et al, 2010;Yu et al, 2013). In this study, we report that Stk40 acts as a repressor of adipogenesis through the translational control of C/EBPβ and C/EBPδ.…”

Arf tumor suppressor and miR-205 regulate cell adhesion and formation of extraembryonic endoderm from pluripotent stem cells

“…Ras/Erk signaling is central to these effects, and drugs that inhibit either Mek or Erk interfere with this process (20). Although Ras potently elicits phospho-Erk expression at the periphery of Arf-null EBs, other markers of the ExEn lineage, including Dab2, Lrp2, and Gata4, were not detected, implying that p19 Arf acts "downstream" of, or parallel to, Ras/Erk signaling to facilitate later stages of ExEn differentiation.…”

“…Generation of ExEn cells in culture depends upon Ras signaling through the Raf-Mek-Erk pathway and can be accelerated by Ras overexpression and blocked by pharmacologic Mek/Erk inhibitors (20). Arf is induced by Ras (14,21), suggesting that each may be required for ExEn specification.…”

Unfolded Protein Response Is Required for the Definitive Endodermal Specification of Mouse Embryonic Stem Cells via Smad2 and β-Catenin Signaling

“…CRL-1821, ATCC (23) and CGR8 (a gift from Austin Smith), were propagated as described previously (24,25). Embryoid bodies (EBs) were formed from ESCs by culturing in ESC medium without leukemia inhibitory factor (Merck Millipore, Billerica, MA).…”