Question

How does the fly control differentiation of epithelial cells to nerve cells so that nerve cells are not over-produced?

Group of answer choices

The Notch receptor is present on epithelial cells. When an epithelial cell develops into a nerve cell, it expresses Delta on its outer cytoplasmic membrane instead of Notch. Delta is a ligand for Notch. When a Delta-bearing nerve cell touches a Notch-bearing epithelial cell, it inhibits the epithelial cell from differentiating into a nerve cell.

As the epithelial cells differentiate into nerve cells, they start to release Delta into the brain. This Delta enters the remaining epithelial cells and acts as a repressive transcription factor to inhibit the transcriptional program that allows epithelial cells to convert to nerve cells.

They convert into nerve cells as long as there is a connecting cell to signal to. Otherwise, they die off.

The Notch receptor is present on epithelial cells. When an epithelial cell develops into a nerve cell, it stops expressing Notch, and instead expresses Delta, which it starts to secrete into the brain. Delta is a ligand for Notch. As more nerve cells develop, they produce enough Delta to signal to the remaining epithelial cells, inhibiting them from differentiating into nerve cells.

Answer 1

Notch signaling pathways are important in cell-cell communication which is achieved by interaction between Notch and ligand Delta or Serrate. Notch bearing cells interact with transmembrane delta ligands which result in cleavage of Notch and nuclear localization of Notch intracellular domain (NCID). NCID interacts with Suppressor of hairless in the nucleus resulting in expression of Enhancer of split genes. These encode transcriptional repressor that act on proneural genes. Lower proneural gene expression decreases expression of Delta ligand and reduction in Notch activation in surrounding cells.

Therefore, When a Delta bearing nerve cell touches a Notch-bearing epithelial cell, it inhibits the epithelial cell from differentiating into a nerve cell.