Characterization of a developmentally regulated mouse embryonic antigen

Area of Science:

• Developmental Biology
• Cell Biology
• Glycoprotein Characterization

Background:

• Mammalian embryonic cell surface glycoprotein (ESGp) expression is developmentally regulated.
• ESGp's biochemical structure varies with embryonic stage and cell type.
• Previous studies suggest ESGp's involvement in cell-cell interactions.

Purpose of the Study:

• To isolate and characterize the developmentally regulated embryonic cell surface glycoprotein (ESGp).
• To investigate the molecular weight variations of ESGp during mouse embryogenesis.
• To determine the cell-type specific expression of ESGp in blastocysts and related cell lines.

Main Methods:

• Electrophoretic analyses to determine molecular weights of ESGp.
• Studies using embryonal carcinoma (EC) cells to differentiate molecular forms.
• Survey of various mouse tissues and cell lines for ESGp expression.

Main Results:

• ESGp presents as a 90 kDa molecule in early cleavage stages (2-8 cell) and morula embryos.
• At the blastocyst stage, ESGp appears as a heterogeneous band (90-110 kDa), composed of three distinct molecules (90, 95, 105-110 kDa).
• Specific molecular weights correlate with distinct cell types: 90 kDa (embryonic ectoderm), 95 kDa (visceral endoderm), and 110 kDa (parietal endoderm/differentiated cells).

Conclusions:

• ESGp exhibits distinct molecular forms associated with specific cell types during mouse embryonic development.
• ESGp expression is polarized to cell-cell contact areas in cultured EC cells, suggesting a role in adhesion.
• ESGp likely mediates intercellular adhesion in both embryonal carcinoma cells and compacting embryos.