Tissue-specific, temporal changes in cell adhesion to echinonectin in the sea urchin embryo

Area of Science:

• Developmental Biology
• Cell Adhesion
• Marine Biology

Background:

• Echinonectin, a dimeric glycoprotein, is present in the hyaline layer of developing sea urchin embryos.
• Both echinonectin and the protein hyalin support embryonic cell adhesion in vitro.
• Previous research indicated hyalin supports cell adhesion, prompting investigation into echinonectin's specific role.

Purpose of the Study:

• To investigate the specificity of cell-echinonectin interactions during sea urchin development.
• To determine if primary mesenchyme cells (PMCs) coordinate a loss of adhesion to echinonectin during ingression, similar to their interaction with hyalin.
• To analyze changes in cell adhesion to echinonectin in different embryonic cell types over time.

Main Methods:

• Utilized a centrifugal force-based adhesion assay to quantify cell-echinonectin interactions.
• Compared adhesion of micromeres, PMCs, presumptive ectoderm, and endoderm to echinonectin at different developmental stages.
• Employed monoclonal antibodies specific to echinonectin to assess its role in combined substrata adhesion.

Main Results:

• Micromeres demonstrated strong adhesion to echinonectin.
• PMCs showed reduced adhesion to echinonectin at the time of ingression, mirroring their decreased adhesion to hyalin.
• Presumptive ectoderm and endoderm exhibited no change in echinonectin adhesion during this period, though initial adhesion was lower compared to hyalin.

Conclusions:

• Echinonectin and hyalin function independently as adhesive substrates for sea urchin embryonic cells.
• PMCs decrease their affinity for echinonectin during ingression.
• Ectodermal cells later increase their affinity for echinonectin, suggesting dynamic changes in cell-substrate interactions during development.