1(2)gl gene regulates late expression of segment polarity genes in Drosophila

To analyse the possible roles of Drosophila tumour suppressor genes, 1 (2)gl and 1 (2)gd, in differentiation programmes of imaginal cells, we investigated their interactions with two segment polarity genes, viz., cubitus interruptus Dominant (ci-D) and engrailed (en), by examining their patterns of expression in tumourous imaginal discs of 1 (2)gl4 or 1 (2)gd1 homozygous larvae. While the 1 (2)gd1 mutation did not have much effect, the areas of expression of ci-D and en in the tumourous discs of 1 (2)gl homozygous larvae were significantly increased and the anterior-posterior compartment boundary was no longer identifiable. To examine if the loss of en expression compartment boundary in 1 (2)gl tumourous discs was due to overproliferation of the posterior compartment cells or due to a deregulated expression of en in the anterior compartment cells, 1 (2)gl4 homozygous cell clones were generated in 1 (2)gl4 enlacZ/++ background. A distinct X-gal staining in 1 (2)gl homozygous clones in the anterior compartment in wing imaginal discs or in adult wings confirmed deregulated ectopic expression of en in 1 (2)gl mutant anterior compartment cells. We suggest that 1 (2)gl is involved in regulating post embryonic expression of segment polarity genes