Problem:
Today, a presenter briefly mentioned that gene expression in sea urchins during development might be manipulated using VP16 and engrailed fusions.
On a slide, it said that expression might be increased by mRNA injection or "VP16 fusion to binding domain of TF" and decreased by antisense morpholinos or "engrailed fusion to binding domain of TF".
I understand mRNA injection and antisense morpholinos, but I am unclear about the roles of VP16 and engrailed in this context.
Can anyone clarify? Please provide correct clearification.