A test for cell autonomy, based on di-cistronic messenger translation

Area of Science:

• Developmental biology
• Genetics
• Molecular biology

Background:

• Understanding gene function requires determining if their effects are cell-autonomous or non-autonomous.
• Homeotic genes, like Ultrabithorax (Ubx), play crucial roles in development but their precise mode of action remains debated.

Purpose of the Study:

• To develop and apply a novel genetic assay for assessing cell autonomy of gene activity.
• To investigate the influence of ectopic Ultrabithorax (Ubx) expression on neighboring cells in Drosophila wing imaginal discs.

Main Methods:

• Utilized the yeast Flp-recombinase target (FRT) system for inducible gene expression.
• Employed beta-galactosidase co-expression to mark cells with ectopic gene activity.
• Inserted a 5' untranslated region (UTR) from the Ultrabithorax (Ubx) gene to mediate di-cistronic mRNA translation.
• Analyzed phenotypic transformations in Drosophila wing imaginal discs.

Main Results:

• Demonstrated efficient and reliable di-cistronic mRNA translation mediated by the Ubx 5' UTR in Drosophila.
• Showed that ectopic Ubx expression in wing discs leads to cell transformation.
• Observed that ectopic Ubx expression strictly correlates with beta-galactosidase reporter gene expression.
• Wing cells ectopically expressing Ubx transformed into intermediates resembling haltere cells.

Conclusions:

• The developed assay effectively tests for cell autonomy of gene function.
• Ectopic Ultrabithorax (Ubx) expression influences neighboring cells, indicating non-autonomous effects.
• The findings contest the traditional view of homeotic genes acting solely as binary switches in development.