Structures of full-length and deleted Ft and Ds proteins. Shown are the cleaved signal sequences (black), cadherin domains (purple), EGF-like domains (green), Laminin-G domains (yellow-green), transmembrane domains (light blue) and the HA tag (dark blue). Sites mutated in ft^fd and ft^G-rv are also shown. ft^fd contains a stop codon in the 9th cadherin domain. ft^G-rv contains a mdg3 retrotransposon insertion (the beginning of its sequence is underlined) that introduces a stop codon in the 27th cadherin domain; it also contains additional rearrangements in the first intron and a previously described insertion in the 33rd cadherin domain (not shown) (Mahoney et al., 1991).

Expression of full-length and deleted ft and ds constructs. (A-F) Expression of full-length and deleted ft and ds constructs in the posterior compartments (right) of ft^G-rv/ft^fd (A-C), ds⁰⁵¹⁴² (D,E) or wild type (F) wing imaginal discs with en-gal4. (A) UAS-ft. (B) UAS-ftΔICD. In both A and B, Ft or the HA-tagged FtΔICD (green and center panels) is concentrated at the cell cortex, and leads to stronger anti-Ds staining (purple and right panels) in the region of misexpression. (C) UAS-ftΔECD; anti-Ft staining (green and center panel) is diffuse and not concentrated at the cell cortex, and does not lead to stronger anti-Ds staining (purple and right panel) in the region of misexpression. There appears to be a slight decrease in Ds levels. (D) UAS-ds. (E) UAS-dsΔICD. In both D and E, anti-Ds staining (green and center panels) is concentrated at the cell cortex, and leads to stronger anti-Ft staining (purple and right panel) in the region of misexpression. (F) UAS-dsΔECD; anti-Ds staining (white) is diffuse and not concentrated at the cell cortex. (G) AyGal4 FLPout clone expressing UAS-dsΔECD and UAS-GFP (green) in a wild-type wing imaginal disc. The clone does not lead to stronger anti-Ft staining (purple and right panel).

Aggregation of S2 cells induced by transfection with full-length and deleted ft and ds constructs. Expression in cells was induced by co-transfection with act-gal4. Cells in A-E were counterstained with rhodamine-labeled phalloidin (purple). (A) Control cells transfected with UAS-GFP (green) did not aggregate. (B,C) Cells co-transfected with UAS-ft, UAS-GFP and either UAS-ds (B) or UAS-dsΔICD (C) aggregated. (D,E) Cells co-transfected with UAS-GFP and either UAS-ftΔECD and UAS-ds (D) or UAS-dsΔECD and UAS-ft (E) did not aggregate. (F,G) Mixture of cells transfected with UAS-ds and UAS-GFP (green), and cells transfected with either UAS-ft (F, red) or UAS-ft ΔICD (G, red) aggregated. Ft (anti-Ft, red and center panel) or FtΔICD (anti-HA, red and center panel) concentrated with Ds (blue and right panels) at the sites of cell contact.

Comparison of overgrowth of wing imaginal discs. Typical wing discs for each genotype are shown at the same magnification. ft^- is ft^G-rv/ft^fd, ds^- is ds^UAO71, and ds^- ft^- is ds^UAO71 ft^G-rv/ds^UAO71ft^fd. (A) Wild type. (B) Overgrowth in ft^-. (C) Rescue of ft^- overgrowth with UAS-ft and act-gal4. (D) Rescue of ft^- overgrowth with UAS-ftΔECD and act-gal4. (E) Potentiation of ft^- overgrowth with UAS-ftΔICD and act-gal4. (F) Mild overgrowth in ds^-. (G) Potentiation of ft^- overgrowth by ds^-.

Assay for rescue of ft^G-rv/ft^fd overgrowth in posterior of imaginal wing discs.en-gal4 (anti-En, green) was used to drive expressions of full-length and deleted ft constructs. All are shown at the same magnification. (A) Wild type. (B). Overgrowth of anterior and posterior wing pouch in ft^G-rv/ft^fd. (C,D) Rescue of overgrowth in posterior wing pouch by UAS-ft (C) or UAS-ftΔECD (D). (E) Failure to rescue overgrowth in posterior wing pouch with UAS-ftΔICD. (A-E) There is no effect on the expression of the wing blade Wg target Vg (purple and right panels).

Overgrowth phenotype induced by expression of UAS-ftΔICD in wild-type wing discs. (A) Control ap-gal4 UAS-GFP wing disc showing dorsal region of expression (green). (B) Overgrowth induced in dorsal cells by ap-gal4 UAS-GFP UAS-ftΔICD. Ventral regions lacking expression in A and B are similar in size. (C,D) Overgrowth induced by hh-gal4 UAS-GFP UAS-ftΔICD in posterior compartment (green) of wing pouch and prospective hinge region. There is similar expression of the wing pouch Wg target Dll (purple and right panel) in anterior and posterior cells in C. The distal ring of wg-lacZ expression (purple and right panel) is similar in width in cells inside (arrowhead) and just anterior to (arrow) the region of misexpression in D. (E,F) Expression of UAS-ftΔICD in the posterior of wing imaginal discs using en-gal4 (E) or hh-gal4 (F). Discs were stained using an antiserum generated against the intracellular domain of Ft (Yang et al., 2002). (E) Expression in ft^G-rv/ft^fd discs. The region of misexpression was identified by the stabilization of Ds (green, left panel); the anti-Ft (purple and right panel) did not crossreact with FtΔICD. (F) Expression in wild-type discs. Endogenous Ft (purple and right panel) was stabilized in the region of FtΔICD expression, identified by the HA tag on FtΔICD (green, left panel). (G) Anti-DE-cadherin (purple and right panel) staining after dorsal expression of UAS-GFP (green) and UAS-ftΔICD using ap-gal4. Shg levels were slightly decreased dorsally.

Effects of full-length and deleted ft constructs on PCP and crossvein spacing. (A-H) Polarity of hairs in adult wings; normal polarity is indicated by blue arrows and abnormal polarity by red arrows. Crossvein spacing is reduced by all constructs. (A) Wild type; positions of the longitudinal (L1-L5) and crossveins (ACV, PCV) are marked. (B) Defects in viable ft¹⁸ mutant. (C) Defects induced by large homozygous ft^G-rv clone (y^-) in the distal region of the wing blade between L2 and L3. The clone occupies the entire region shown. (D,E) Apparent partial rescue of PCP defects of ft^G-rv/ft^fd wing with act-gal4 and UAS-ft (D) or UAS-ftΔECD (E). (F-H) Proximal PCP defects induced in wild-type wing with act-gal4 and UAS-ft (F), UAS-ftΔECD (G) or UAS-ftΔICD (H). Defects were milder with UAS-ftΔECD. (I-L) Polarity of abdominal hairs. (I) Wild type. (J) Disruption in ft^G-rv/ft^fd. (K,L) Partial rescue of ft^G-rv/ft^fd by act-gal4 and UAS-ft (K) or UAS-ftΔECD (L).