Signaling Pathways Orchestrate the Transition from Naive to Formative Pluripotency in Mouse Embryonic Stem Cells

Core Concepts

ERK signaling drives the transition from naive to formative pluripotency in mouse embryonic stem cells by both destabilizing the naive state transcription factor network and sustaining the expression of the core pluripotency factor Oct4.

Abstract

The content examines the role of mitogen-activated protein kinase (ERK1/2) signaling in the transition from naive to formative pluripotency in mouse embryonic stem cells (ESCs). Key highlights: ERK activation leads to the elimination of Nanog, a key transcription factor of the naive state, precipitating the breakdown of the naive state gene regulatory network. Cell-to-cell variability in pERK dynamics results in the metachronous downregulation of Nanog and exit from the naive state. While knockdown of Nanog allows exit from the naive state without ERK activation, these cells fail to upregulate formative genes and become trapped in an indeterminate state. ERK signaling is required not only to dismantle the naive state but also to maintain the expression of the core pluripotency factor Oct4, which is essential for the progression to the formative state. The detailed mechanisms by which ERK regulates Nanog protein stability and Oct4 gene expression remain to be determined. In summary, the study demonstrates that a single signaling pathway, ERK, can both drive the exit from a developmental state and safeguard the progression to the successor state during the transition from naive to formative pluripotency in mouse ESCs.

Stats

"Withdrawal of 2i and culturing cells in only N2B27 basal media, opens the path to differentiation via transition to formative pluripotency." "Treatment with the MEK inhibitor [MEK(i)] PD0325901 to block ERK activation was sufficient to fully maintain ESC colony formation ability after 30h." "Treatment with RSK(i) for 30h, cells formed fewer ESC colonies and showed more extensive downregulation of the RGd2 reporter than cells in medium only." "Higher levels of ERK activity resulted in a lower number of Nanog positive cells at 20hrs."

Quotes

"ERK activity elicits loss of Nanog protein before Esrrb." "ERK signalling both dismantles the naïve state and preserves pluripotency." "Without ERK input cells become stranded in an indeterminate state."

Key Insights Distilled From

ERK signalling orchestrates metachronous transition from naïve to formative pluripotency

by Mulas,C., St... at www.biorxiv.org 07-20-2023

https://www.biorxiv.org/content/10.1101/2023.07.20.549835v1

Deeper Inquiries

How do the specific mechanisms by which ERK regulates Nanog protein stability and Oct4 gene expression differ?

ERK Regulation of Nanog Protein Stability: ERK signaling leads to the destabilization of Nanog protein by phosphorylating it directly. Phosphorylation of Nanog by ERK may trigger its degradation, resulting in the downregulation of Nanog protein levels. The destabilization of Nanog by ERK is a key step in the breakdown of the naive state gene regulatory network, facilitating the transition from naive to formative pluripotency. ERK Regulation of Oct4 Gene Expression: ERK activity is essential for maintaining Oct4 expression as cells exit the naive state and transition to the formative state. The specific mechanisms by which ERK regulates Oct4 gene expression are not fully elucidated in the study, but it is suggested that ERK sustains Oct4 expression to secure cell state transition. In the absence of ERK activity, cells lose Oct4 expression, which hinders their ability to upregulate formative transcription factors and progress with the transition to formative pluripotency.

How do the specific mechanisms by which ERK regulates Nanog protein stability and Oct4 gene expression differ?

ERK Regulation of Nanog Protein Stability: ERK signaling leads to the destabilization of Nanog protein by phosphorylating it directly. Phosphorylation of Nanog by ERK may trigger its degradation, resulting in the downregulation of Nanog protein levels. The destabilization of Nanog by ERK is a key step in the breakdown of the naive state gene regulatory network, facilitating the transition from naive to formative pluripotency. ERK Regulation of Oct4 Gene Expression: ERK activity is essential for maintaining Oct4 expression as cells exit the naive state and transition to the formative state. The specific mechanisms by which ERK regulates Oct4 gene expression are not fully elucidated in the study, but it is suggested that ERK sustains Oct4 expression to secure cell state transition. In the absence of ERK activity, cells lose Oct4 expression, which hinders their ability to upregulate formative transcription factors and progress with the transition to formative pluripotency.

What other signaling pathways or transcriptional regulators might interact with the ERK pathway to fine-tune the transition from naive to formative pluripotency?

Other signaling pathways or transcriptional regulators that might interact with the ERK pathway to fine-tune the transition from naive to formative pluripotency include: Wnt/β-catenin signaling: Known to play a role in pluripotency and differentiation, crosstalk between the Wnt/β-catenin pathway and ERK signaling could influence the transition process. TGF-β signaling: TGF-β signaling pathways are involved in cell fate decisions and could interact with ERK signaling to modulate the transition from naive to formative pluripotency. Notch signaling: Notch signaling is crucial for cell fate determination and could potentially interact with ERK signaling to regulate the pluripotency transition. SOX2 and KLF4: These transcription factors are key regulators of pluripotency and could potentially interact with the ERK pathway to fine-tune the transition process. The interplay between these pathways and regulators, along with ERK signaling, could contribute to the precise control of the transition from naive to formative pluripotency.

Could the insights from this study on the role of ERK signaling in pluripotency transitions be leveraged to improve the directed differentiation of embryonic stem cells towards specific lineages?

The insights from this study on the role of ERK signaling in pluripotency transitions could be leveraged to improve the directed differentiation of embryonic stem cells towards specific lineages in the following ways: Optimizing differentiation protocols: Understanding the role of ERK signaling in the transition from naive to formative pluripotency can help in optimizing differentiation protocols by modulating ERK activity levels. Targeted manipulation: Targeted manipulation of ERK signaling pathways during differentiation could enhance the efficiency and specificity of lineage commitment. Combination with other pathways: Combining insights from ERK signaling with other signaling pathways and transcriptional regulators could lead to more precise control over the differentiation process. Development of novel strategies: The study could inspire the development of novel strategies or small molecules that target ERK signaling to enhance directed differentiation towards specific lineages. Personalized medicine: Understanding the role of ERK signaling in pluripotency transitions could also have implications for personalized medicine and regenerative therapies by enabling tailored approaches for cell-based therapies. Overall, the findings on ERK signaling in pluripotency transitions provide a foundation for further research and potential applications in improving the directed differentiation of embryonic stem cells towards specific lineages.