QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 1 November 2006
doi: 10.1242/dev.02675

This Article Summary Full Text Full Text (PDF) Supplementary Material Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in Development Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ekas, L. A. Articles by Bach, E. A. Search for Related Content PubMed PubMed Citation Articles by Ekas, L. A. Articles by Bach, E. A.

JAK/STAT signaling promotes regional specification by negatively regulating wingless expression in Drosophila

¹ Pharmacology Department, New York University School of Medicine, New York, NY 10016-6402, USA.
² Children's Cancer Research Laboratory, Pediatrics-Hematology/Oncology, New York Medical College, Valhalla, NY 10595-1690, USA.

View larger version (122K): [in a new window]   Fig. 1. Upd acts in the early eye disc to promote regional specification. (A,B) upd>GFP expression (green) in first (A) and second (B) instar eye discs; Dlg marks the cell outline (red). (C,D) upd mRNA in situ hybridization analysis. upd is transcribed at the posterior midline in late second/early third (C), but not in mid-third (D) instar eye discs. (E-H) Expression of 10XSTAT92E-GFP (abbreviated 10XSTAT-GFP; green), Dlg (blue) and dpp-lacZ (anti-ß-Gal, red) (E,F) or wg-lacZ (anti-ß-Gal, red) (G,H). 10XSTAT-GFP is expressed in the posterior domain of first (E,G) and second (F,H) instar eye discs. This expression partially overlaps with dpp (E,F) and abuts wg (G,H). (I,J) Scanning electronic micrographs of wild-type (I) and ey-GAL4, UAS-upd (ey>upd) (J) adult heads, dorsal view. Overexpression of upd results in the expansion of the dorsal eye domain into the lateral head cuticle, reducing the inter-eye distance (arrow). ey>upd animals also have patterning defects in both the eye and the head cuticle. In all images, eye discs are oriented with anterior towards the left and dorsal upwards.

View larger version (118K): [in a new window]   Fig. 2. Stat92E is required for eye development. In panels A-C,F,G clones were generated using ey-flp in a Minute background. (A) +M+. (B,C) stat92E85C9 M+. The loss of stat92E results in a small-eye (B) or a no-eye (C) phenotype. These adults also exhibit excess head cuticle (C, arrow). (D) stat92E85C9 M+ adults carrying a UAS-3HA stat92E transgene. The stat92E85C9 M+ small-eye phenotype can be rescued by the ectopic expression of a full-length copy of stat92E. (E) Wild-type adults carrying a UAS-3HA stat92E transgene. Overexpression of this transgene using the ey-GAL4 driver (ey>stat92E) does not alter the size of the adult eye. (F) stat92E397 M+. (G) stat92E06346 M+. Like stat92E85C9, these stat92E hypomorphic alleles result in a reduction in the size of the adult eye (F,G). (H,H') Adults carrying stat92E85C9 clones generated using ey-flp in a wild-type (i.e. non-Minute) background. (H) Dorsal view; (H') lateral view. Both ectopic cuticle (arrow) and ambiguous, ectopic structures (arrowheads) are observed in the eye field of adults carrying stat92E85C9 clones. (I) Dorsal view of a + M+ adult that exhibits symmetrically patterned eyes and head cuticle. (J,K) Dorsal views of a stat92E85C9 M+ adult that lacks ommatidia, has an altered pattern of macrochaete and excess head cuticle (arrow) (J) or exhibits only a rudimentary head (K). (L) Adult carrying a UAS-wg transgene in a wild-type background. Overexpression of a wg transgene using the ey-GAL4 driver (ey>wg) results in a no-eye phenotype indistinguishable from the stat92E85C9 M+ no-eye phenotype (C).

View larger version (95K): [in a new window]   Fig. 3. Loss of JAK/STAT signaling results in changes in eye disc morphology and ectopic wg expression. Clones were generated using ey-flp in a Minute (A-E) or non-Minute (F,H,I) background. (A,B) A third instar dpp-lacZ; + M+ (A) or dpp-lacZ; stat92E85C9 M+ (B) eye disc. Heterozygous tissue (green), Elav (red), dpp-lacZ (blue). dpp is absent from the dorsal domain of stat92E85C9 M+ eye discs (B). (C) A third instar dpp-lacZ; stat92E85C9 M+ eye disc. Heterozygous tissue (green), Wg (red), dpp-lacZ (blue). dpp is lost from the dorsal domain of the eye disc and Wg expression is expanded into this region (yellow arrow). The morphogenetic furrow [marked by dpp-lacZ (anti-ß-Gal) expression] moves only through the ventral region of stat92E85C9 M+ eye discs (B,C); these discs also exhibit abnormal dorsal outgrowths (white arrows in B,C). (D,E) A third instar wg-lacZ; + M+ (D) or wg-lacZ; stat92E85C9 M+ (E) eye disc. Heterozygous tissue (green), wg-lacZ (anti-ß-Gal, red), Elav (blue). wg is ectopically expressed in stat92E85C9 M+ discs and expansion of both the dorsal wg domain and the ventral wg domain (arrowhead) is evident (E). (F) A third instar wg-lacZ; stat92E85C9 eye disc. Wild-type tissue (green), wg-lacZ (red), Dlg (blue). wg is expanded in stat92E85C9 clones (arrow). (G) A third instar hopM13/Y; wg-lacZ eye disc. X-gal staining indicates that wg is ectopically expressed throughout most of the eye disc in hop mutants. (H,I) Dorsal views of adult heads. X-Gal staining of adults carrying wg-lacZ (blue) with an FRT82B (control) (H) or stat92E85C9 (I) chromosome. Ectopic wg is observed in stat92E85C9 clones (marked by white ommatidia) in the eye field, frequently at the base of ectopic outgrowths (arrows) (I). This is never seen in wild-type (FRT82B) clones (H).

View larger version (97K): [in a new window]   Fig. 4. Ectopic JAK/STAT signaling represses wg expression. (A,A') A third instar eye disc carrying hop flip-out clones and dpp-lacZ (Act>>hop/dpp-lacZ; UAS-GFP). hop flip-out clones (green) do not induce dpp-lacZ (anti-ß-Gal, red) expression. (A) Merge; (A') dpp-lacZ single channel. (B,B') A third instar eye disc carrying hop flip-out clones and wg-lacZ (Act>>hop/wg-lacZ; UAS-GFP). hop flip-out clones (green) repress wg-lacZ (anti-ß-Gal, red) expression in an autonomous manner. Repression is observed in the dorsal wg domain (outlined clones) and in the ventral domain (arrowheads). (B) Merge; (B') wg-lacZ single channel. (C) A third instar eye disc carrying ey>upd and wg-lacZ (ey>upd; wg-lacZ). Dlg (green), wg-lacZ (red), Elav (blue). Ectopic upd expression completely represses dorsal wg and strongly represses ventral wg (yellow arrow), allowing precocious photoreceptor differentiation from the lateral margin (arrowhead). (D-D') A third instar wing disc carrying hop flip-out clones and wg-lacZ (Act>>hop/wg-lacZ; UAS-GFP). hop flip-out clones (green) autonomously repress wg (red) in the notal region of the wing disc. (D) Merge; (D') magnified view of D; (D') wg-lacZ single channel in D'. (E,F) Dorsal views of adult heads carrying a stat92E85C9 chromosome in a Minute background alone (E) or with the hypomorphic mutation wgCX3/+; stat92E85C9 M+ (F). Reducing the dose of wg slightly improves the stat92E85C9 M+ adult phenotype. (G) Reducing the dose of wg, using the wgCX3 allele, significantly increases the number of stat92E85C9 M+ flies that eclose from the pupal case. Whereas only 9.7% of flies stat92E85C9 M+ eclose (n=258), flies also carrying the wgCX3 mutation hatch at a rate of 31.2% (n=266).

View larger version (36K): [in a new window]   Fig. 5. Stat92E regulates wg through a small enhancer in the wg 3' cis genomic region. (A) Schematic representation of 20 kb of the wg gene, from just 5' of the start site, through untranslated and coding exons (turquoise and red boxes, respectively), and including 9 kb of 3' cis genomic region. wg2.11Z is a 263 bp enhancer from the wg 3' cis genomic region that is sufficient to recapitulate wg expression in the dorsal eye (B). This 20 kb region contains only one putative Stat92E binding site (TTC(N)3GAA; red arrow), which resides downstream of the wg2.11Z enhancer. (B-D) X-gal staining of wg2.11Z (blue). Third instar eye discs carrying the wg2.11Z reporter (B) and a stat92E85C9 chromosome in a non-Minute (C) or Minute (D) background. Clones were generated using ey-flp. wg is expanded in stat92E85C9 non-Minute (C) and Minute (D) clones in a manner similar to wg-lacZ (see Fig. 3E,F). Outgrowths of tissue containing ectopic wg2.11Z are evident during larval stages (C, arrow). (E,E') A third instar eye disc carrying the wg2.11Z reporter (anti-ß-Gal, red) and hop flip-out clones (Actin>>GAL4; UAS-hop/wg2.11Z; green). hop flip-out clones autonomously repress wg2.11Z expression. (E) Merge; (E') wg2.11Z single-channel.

View larger version (95K): [in a new window]   Fig. 6. The JAK/STAT repression of wg in the disc epithelium is not mediated by known wg regulators. (A,B) A third instar eye disc carrying wg-lacZ in a wild-type background (A) or in a stat92E85C9 Minute background (B). Heterozygous tissue (green), Dac (red), wg-lacZ (anti-ß-Gal, blue). Dac expression is lost in tissue that ectopically expresses wg (B). (C,D) A third instar eye disc carrying a wild-type (C) or a stat92E85C9 M+ (D) chromosome. Heterozygous tissue (green), Hth (red), Elav (blue). Hth is expanded in both dorsal and ventral domains of stat92E85C9 M+ eye discs (D, arrowheads). (E,F) A third instar eye disc carrying pnr>GFP in a wild-type (E) or a hopM13/Y background (F). pnr>GFP (green) and Phalloidin (red). pnr is expanded posteriorly in the peripodial membrane of hopM13 eye discs (F); increased pnr expression also evident in xz sections from the anterior (yellow box) and posterior (blue box) regions of the disc. (G,H) A late-third instar eye disc carrying pnr>GFP in a wild-type (G) or GMR-upd (H) background. pnr>GFP (green) and Phalloidin (red). Ectopic upd expression represses pnr to the region anterior to the furrow (H, arrow). (I) Model of JAK/STAT activity in Drosophila eye imaginal discs. fng, fringe; Nact, activated Notch receptors; Iro-C, Iroquois-C; A, apical; B, basal; D, dorsal; V, ventral; DP, disc proper; PM, peripodial membrane.