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Eye suppression, a novel function of teashirt, requires Wingless signaling

Amit Singh, Madhuri Kango-Singh and Y. Henry Sun*

Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, 11529 Taiwan, Republic of China



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  		Fig. 1. Ectopic tsh can induce HTH and suppress eye development. (a) dpp>tsh, which drives expression of tsh along the lateral and posterior margin of the eye disc, caused splitting of the endogenous eye (arrow indicates the ventral eye) and induced an ectopic eye at the base of the antenna (arrowhead) in the pharate adult. All eye discs in this and subsequent figures are oriented anterior towards the left and dorsal towards the top. (b,c) dpp>tsh eye disc (photoreceptors labeled by ELAV, blue; HTH, red). Eye disc (E) is highly reduced (arrow) relative to the antenna disc (AN). (d) dpp>2Xtsh caused suppression of the ventral eye. (e) ey>tsh caused complete loss of eye (ELAV, blue) and ectopic induction of HTH (red). The size of the eye disc is extremely reduced. (f) ey>tsh adult showed complete loss of eye. (g) dpp>tsh in an hth1422-4/+ background resulted in pharate adult with rescue of the dpp>tsh split-eye phenotype and (h) dpp>tsh+hth caused complete eye loss.

 


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  		Fig. 2. Expression pattern of tsh relative to hth and EY in eye and wing discs. tsh-GAL4 (Shiga et al., 1996Go) driven UAS-GFP and hth1422-4 (an enhancer trap insertion in hth) (Kurant et al., 1998Go) and anti-EY antibody (Halder et al., 1998Go) were used to examine the expression patterns of tsh, hth and EY (GFP, green; hth-lacZ, red; and EY, blue) in (a) first instar eye-antenna disc, (b) second instar eye disc, (c) early third instar eye disc, (d) late third instar eye disc and (e) late third instar wing disc. Differentiated photoreceptors in d were marked by ELAV (blue). (AN, antenna disc; E, eye disc)

 


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  		Fig. 3. DV differential effects of tsh misexpression. (a) bi>GFP marks bi-GAL4 expression domains along the dorsal and ventral margins of the eye disc, and in a dorsal sector of the antennal disc. The DV axis (as defined by the ventral wg and dorsal dpp expression) of the antenna disc (Theisen et al., 1996Go) is reversed from that of the eye disc. (b) bi>tsh caused eye suppression and ectopic HTH (red) induction only in the ventral eye margin (arrow) of the eye disc. The eye disc is also enlarged. (c) bi>tsh pharate adult showed ventral eye suppression (arrow) and dorsal eye overgrowth. (d) bi>hth adult showed eye suppression on both dorsal and ventral eye (arrows). The adult eye phenotype was usually more severe than the disc phenotype. (e) Act>tsh clone (marked by GFP: green) induced HTH (red) autonomously and suppressed eye development (ELAV: blue) in the ventral margin of the eye disc (arrowhead). Clone in the dorsal margin did not induce HTH but caused overgrowth (arrow). Act>tsh clones were not marked in adults, but flies with clone induction showed ventral suppression (f, arrow) or dorsal enlargement (g, arrow) in the eye.

 


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  		Fig. 4. tsh mutant clones can cause ventral enlargement and dorsal suppression in eye. (a) tsh8 clones were generated by X-ray irradiation of w; tsh8/tshA8 larvae. The tsh8 clones were marked by the loss of the tshA8 mini-white reporter in the adult eye. (b) Wild-type expression of the tshA8 reporter, a P[lacW] insertion at tsh locus and expresses in the anterior half of the adult eye. (c,d) tsh8 clones located at the ventral margin caused overgrowth (arrow). (e-g) tsh8 clones were not marked in the disc, but eye discs treated for clone induction could have ventral enlargement (e,f, arrow) and ectopic eye field (g, arrow). (h,i) tsh8 clones located in the anterior dorsal eye can suppress eye (arrow). (j) tsh8 clone induction can cause nearly complete elimination of the dorsal eye field (arrow).

 


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  		Fig. 5. TSH collaborates with WG signaling for ventral eye suppression. (a) Act>tsh+arm clone (marked by GFP, green) suppressed eye fate (ELAV, blue) by ectopic induction of HTH (red) in both dorsal (arrow) and ventral (not shown) domains. (b) Act>arm clone did not always suppress eye development. Two Act>arm clones (GFP: green) in the eye disc; one near the margin could suppress (arrow), but the other on the margin could not (arrowhead). (c) Act>tsh+wg clone (GFP, green) also suppressed eye by ectopic HTH (red) induction near the dorsal margin. (d) bi>tsh+wg resulted in ectopic induction of HTH (red) and eye suppression on the dorsal and ventral margins in the in adult eye. (e) Act>tsh+dTCF{Delta}N clones (GFP, green) did not suppress eye fate. (f) bi >tsh+dTCF{Delta}N did not induce HTH (red) or suppress eye fate on the dorsal or ventral margin in adult. (g) Act>tsh+sgg clone failed to suppress eye development in the ventral margin (arrow).

 


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  		Fig. 6. Effect of tsh on growth in eye disc. (a) Act>GFP clones (GFP, green) were equally distributed in both dorsal and ventral region in eye disc. Distribution was also equivalent before and after MF. (b) Act>tsh+GFP clone (GFP: green) in the dorsal region in the eye disc caused overgrowth. (c) The ventral Act>tsh+GFP clone (GFP, green) did not cause overgrowth.

 


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  		Fig. 7. DV differential functions of tsh in the antennal disc but not in the wing disc. (a-d) Effects of tsh misexpression in wing disc (anterior is towards the left and ventral is towards the top). (a) Act>tsh clone (GFP, green) could induce HTH (red) in a cell-autonomous manner. (b) Act>tsh located in the wing pouch region did not suppress WG (red). (c) dpp>tsh caused a splitting of the wing pouch by ectopic induction of HTH (red) along the AP compartmental boundary (arrow). (d) bi>tsh could split the wing pouch by ectopic induction of HTH (red). (e) bi>hth did not suppress WG (green) and did not split the wing pouch. (f-j) Effects of tsh misexpression in the antennal disc. Note that the DV axis in the antennal disc (dorsal is upwards and ventral is downwards in these figures) is inverted compared to that of the eye disc. (f,g) Act>tsh clone (GFP, green) located in the ventral wg expression domain (arrow) resulted in duplication of the antenna field in the disc (f) and in an adult (g). (h) Act>tsh clone (GFP: green) located in the anterior (arrow) or posterior (arrowhead) proximal regions did not affect HTH (red) and caused no ectopic eye induction (ELAV, blue). (i) Act>tsh clone in the DP region can cause overgrowth. (j) An Act>tsh clone in the anteroventroproximal region caused ectopic eye formation (ELAV, blue, arrow).

 

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