Yap1 safeguards mouse embryonic stem cells from excessive apoptosis during differentiation

Area of Science:

• Stem cell biology
• Cell death regulation
• Molecular mechanisms of differentiation

Background:

• Embryonic stem cells (ESCs) undergo significant cell death (approx. 30%) upon exiting self-renewal.
• The regulators controlling this post-self-renewal cell death are largely unknown.
• Yap1, a Hippo pathway effector, has known roles in development and cancer but its function in ESC differentiation is poorly understood.

Purpose of the Study:

• To investigate the role of Yap1 in regulating cell survival during embryonic stem cell differentiation.
• To elucidate the molecular mechanisms by which Yap1 influences apoptosis in differentiating ESCs.

Main Methods:

• Generation and analysis of Yap1-deficient embryonic stem cells.
• Assessment of cell viability and apoptosis markers during ESC differentiation.
• Gene expression analysis of apoptosis-related genes regulated by Yap1.
• Functional studies involving modulation of Yap1 target genes.

Main Results:

• ESCs lacking Yap1 exhibit massive cell death after exiting self-renewal.
• Yap1 specifically protects differentiating ESCs, not self-renewing ones, from apoptosis.
• Yap1 activates anti-apoptotic genes and suppresses pro-apoptotic genes, modulating mitochondrial priming.
• Modulating individual Yap1 target genes affects cell survival during differentiation.

Conclusions:

• Yap1 plays a critical, context-dependent pro-survival role during ESC differentiation.
• Yap1 acts as a key regulator balancing cell survival and death during cell fate transitions.
• Understanding Yap1's function provides insights into maintaining genomic stability and developmental processes.