EPITHELIAL HYPERPLASIA OF IMAGINAL DISCS INDUCED BY MUTATIONS IN DROSOPHILA TUMOR-SUPPRESSOR GENES - GROWTH AND PATTERN-FORMATION IN GENETIC MOSAICS

Lethal mutations in the giant discs (Igd) and fat (ft) tumor suppresso r genes of Drosophila cause epithelial hyperplasia in all imaginal dis cs. By contrast, mutations in the vestigial (vg) gene adversely affect cell viability in the wing imaginal discs and consequently cause loss of pattern in the adult wings. However, combining homozygous Igd or f t mutations with homozygous vg(1) increases the size of the wing imagi nal discs and partially restores the bristle pattern in the wings of p harate adults. Comparable pattern restoration in vg(1) wings is also i nduced by a newly isolated weak hypomorphic Igd(3) allele. Further, mo saic analysis revealed that whereas Igd clones generated by the Minute technique display abnormal differentiation, those induced in a homozy gous vg(1) background exhibit autonomous restoration of wing pattern. These results suggest that pattern restoration in vg(1) wings can serv e as an assay for hyperplasia induced by mutations in Drosophila tumor suppressor genes. (C) 1995 Academic Press, Inc.