Requirement for ERK MAP kinase in mouse preimplantation development

Area of Science:

• Developmental Biology
• Cell Signaling

Background:

• Preimplantation development is critical for pregnancy, yet early cell division mechanisms before compaction remain unclear.
• Compaction and blastocyst formation are well-studied, but the preceding stages require further investigation.

Purpose of the Study:

• To elucidate the role of extracellular signal regulated kinase (ERK) mitogen-activated protein (MAP) kinase in early embryonic cell division.
• To investigate the impact of ERK pathway inhibition on cell division, cell-cell adhesion, and gene expression during preimplantation development.

Main Methods:

• Inhibition of ERK activation in mouse embryos at the late two-cell stage.
• Analysis of cell cycle progression (G2 phase arrest) and cell-cell adhesion.
• Microarray analysis to assess gene expression changes.
• Investigation of ERK's role in conjunction with cadherin-mediated adhesion.

Main Results:

• ERK inhibition caused reversible G2 arrest at the four-cell stage.
• Arrested embryos exhibited weakened cell-cell adhesion.
• Gene expression largely proceeded normally upon release, but some genes, including those for intercellular adhesion molecules, showed altered profiles.
• ERK inactivation in eight-cell embryos caused arrest only when cadherin-mediated adhesion was disrupted.

Conclusions:

• ERK mitogen-activated protein (MAP) kinase signaling is essential for cell division in early mouse embryos (two-cell to eight-cell stages).
• ERK pathway positively regulates the expression of intercellular adhesion molecules.
• A parallelism exists between gene expression programs and developmental progression before compaction.