Temporal control of gap junction assembly in preimplantation mouse embryos

Area of Science:

• Developmental Biology
• Cell Biology
• Molecular Biology

Background:

• Gap junctions are crucial for cell-cell communication during embryonic development.
• The formation of gap junctions during mouse compaction (8-cell stage) is a precisely timed process.
• The relationship between gap junction assembly and DNA replication timing remains unclear.

Purpose of the Study:

• To investigate the temporal relationship between DNA replication and gap junction assembly during early mouse development.
• To determine if DNA replication in specific cell cycles influences gap junction formation.
• To elucidate the molecular mechanisms underlying the timing of gap junction assembly.

Main Methods:

• Treatment of mouse embryos with aphidicolin, a DNA synthesis inhibitor, during specific cell cycles (2nd, 3rd, and 4th).
• Assessment of gap junctional coupling using electrophysiological techniques.
• Immunofluorescence analysis to detect connexin43 localization in plasma membranes.

Main Results:

• Inhibition of DNA synthesis during the 3rd and 4th cell cycles did not affect gap junction formation.
• A 10-hour delay in DNA synthesis during the 2nd cell cycle resulted in the failure of gap junction coupling.
• This failure correlated with impaired insertion of nascent connexin43 into plasma membranes.

Conclusions:

• DNA replication during the 2-cell stage is critical for the timely establishment of gap junctional coupling.
• A developmental clock, initiated by events around the second DNA replication cycle, regulates gap junction assembly.
• This clock influences the post-translational processing and membrane insertion of connexin43.