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Manipulation of gap junctional communication during compaction of the mouse early embryo
Abstract:
Three treatments that prevent cell flattening during compaction of the mouse preimplantation embryo were assessed for their effects on the onset of gap junctional communication. Medium low in calcium (LCM) and an antiserum to an embryonal carcinoma cell line (anti-EC; Johnson et al. 1979) both prevented the establishment of coupling between blastomeres of the 8-cell embryo as assessed by transmission of carboxyfluorescein or by ionic coupling. Since neither of these agents prevents the contact-mediated induction of cell polarity that occurs at this stage, it is concluded that the induction of this process is not signalled via gap junctions. A monoclonal antibody (ECCD-1; Yoshida-Noro, Suzuki & Takeichi, 1984), that recognizes more specific components of the calcium-dependent cell adhesion system, failed to prevent the onset of junctional coupling. This suggests that the onset of junctional coupling is not dependent upon extensive cell apposition and that the requirement for extracellular Ca2+ resides at a level other than that of cell adhesion. Moreover, neither LCM nor anti-EC could reverse cell coupling once it had become established despite their complete reversal of cell flattening.
Insights
Treatments preventing mouse embryo cell flattening, like low calcium medium (LCM) and anti-EC antiserum, blocked gap junction communication. This indicates cell polarity induction does not rely on gap junctions.
Area of Science:
- Developmental Biology
- Cell Biology
- Embryology
Background:
- Compaction is a critical process in mouse preimplantation embryo development.
- Gap junctional communication is essential for intercellular signaling during early development.
- Cell flattening is a morphological change observed during embryonic compaction.
Purpose of the Study:
- To investigate the relationship between cell flattening and the onset of gap junctional communication.
- To determine if gap junctions are involved in the induction of cell polarity during compaction.
- To explore the role of calcium-dependent cell adhesion in establishing junctional coupling.
Main Methods:
- Assessing the effects of low calcium medium (LCM) on blastomere coupling.
- Utilizing an antiserum to embryonal carcinoma cells (anti-EC) to inhibit cell adhesion.
- Employing a monoclonal antibody (ECCD-1) targeting specific calcium-dependent adhesion molecules.
- Measuring intercellular communication via carboxyfluorescein and ionic coupling.
Main Results:
- LCM and anti-EC prevented the establishment of gap junctional coupling in 8-cell mouse embryos.
- These treatments did not inhibit the contact-mediated induction of cell polarity.
- ECCD-1 antibody did not prevent the onset of junctional coupling.
- Reversal of cell flattening by LCM or anti-EC did not restore established cell coupling.
Conclusions:
- Cell polarity induction during compaction is independent of gap junction signaling.
- The onset of junctional coupling does not require extensive cell apposition.
- Extracellular calcium's role in coupling is not solely dependent on cell adhesion mechanisms.