The Drosophila Epidermal Growth Factor Receptor does not act in the nucleus

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Mammalian epidermal growth factor receptor (EGFR) family members can translocate to the nucleus.
• Nuclear EGFR functions, involving full-length proteins or cleaved cytoplasmic domains, impact tumor progression and drug resistance in cancer cells.

Purpose of the Study:

• To investigate whether the single Drosophila EGFR homolog exhibits nuclear localization.
• To determine if Drosophila EGFR possesses nuclear functions analogous to its mammalian counterparts.

Main Methods:

• Constructed chimeric EGFR proteins fused with DNA-binding and transcriptional activation domains.
• Overexpressed chimeric proteins in cultured cells and in vivo to assess transcriptional activity.
• Utilized genome editing to introduce DNA-binding and activation domains into the endogenous Drosophila Egfr locus.

Main Results:

• Overexpression of a chimeric Drosophila EGFR with activation domains led to strong transcriptional reporter activation, independent of cleavage and endocytosis.
• Drosophila EGFR fused solely to a DNA-binding domain did not exhibit transcriptional activity.
• Genome editing at the endogenous Egfr locus did not result in detectable reporter expression, even in oncogenic contexts.

Conclusions:

• The cytoplasmic domain of Drosophila EGFR does not access the nucleus at physiological levels.
• Nuclear EGFR functions appear to be a later evolutionary development, emerging after the divergence of invertebrates and vertebrates.