The Drosophila EcR-Hippo component Taiman promotes epithelial cell fitness by control of the Dally-like glypican and Wg gradient

Colby K. Schweibenz
Victoria C. Placentra
Kenneth H. Moberg author has email address

Department of Cell Biology, Emory University School of Medicine
Graduate Program in Biochemistry, Cell, and Developmental Biology
Graduate Program in Genetics and Molecular Biology, Emory University

https://doi.org/10.7554/eLife.97803.1

Open access
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Figures and data

tai^low cells survive in a homotypic environment but die in a heterotypic environment.
(A-A’) 3^rd larval instar tai^k15101/Df(2L)ED678 wing disc stained with anti-cleaved Dcp-1 (cDcp1; red) and nuclei (DAPI; blue). (B-C) hsFlp generated clones of control FRT40A (B-B”) or tai^k15101,FRT40A (C-C”) cells marked by the absence of GFP (green) and co-stained for cDcp-1 (red) and nuclei (DAPI; blue). Magnified insets are provided. (D) Quantification of cDcp-1 in tai^k15101/Df(2L)ED678 heterotypic discs or tai^k15101 clones calculated by percent Dcp1-positive area/total clone area (Student t-test, p <0.0001).

Modification of tai^lowclone survival in the adult eye.
Adult female eyes of the indicated genotypes: (A) tai^k15101/Df(2L)ED678; (B-C) eyFLP mosaic eyes with w-;FRT40A flipped over (B) tai^k15101,FRT40A or (C) FRT40A,m-w⁺; (D-H) eyFLP mosaic eyes with tai^k15101;FRT40A flipped over FRT40A,m-w⁺ in the background of (D) hid¹, (E) Df(3L)H99, (F) wts^x1, (G) Apc^MI01007, or (H) Apc2^N175K,Apc^Q8.

Alleles from the eye screen also modify tai^low clone survival in L3 wing pouch
(A-G) Larval wing discs bearing hsFlp/FRT-generated 50hr-old tai^low clones (GFP-negative) either (B) alone, or in the background of the indicated alleles (C-G). Twinspots appear brighter due to two copies of GFP. (H) Quantification of control(FRT40A) or tai^low size ratio (area ratio of clone:twin-spot) alone (-) or in the indicated genetic backgrounds.. ****p <0.001, ***p= 0.0003, *p = 0.0157, ns = not significant (One-way ANOVA with Dunnett post hoc test).

tai promotes expression of the Wg pathway reporter nkd-lacZ.
(A-C) Expression of the nkd-lacZ reporter (greyscale) in (A-A”) control (en>GFP,RFP), (B-B”) Tai overexpressing (en>tai,GFP), or (C-C”) Tai-depleted larval wing discs. (D) Relative anti-ßGal fluorescence intensity on either side of the A-P boundary among pouch cells located just below the D/V boundary. (E) Mean relative fluorescence intensity plotted as a ratio of posterior to anterior intensity. RFP vs tai *p=0.0004; RFP vs tai^RNAi *p<0.0001 (Unpaired student t-test with Welch’s correction).

Tai is required for the auto-inhibitory loop that refines wg transcription.
(A-C) Expression of the wg-lacZ reporter in enGal4 larval wing discs as detected by anti-ßGal staining (white in A-C, black in A’-C’) in control RFP (A), Tai-depleted (B), or Tai overexpressing (C) discs. Arrow in B’ indicates failure to refine wg-lacZ to the DV boundary in P-domains depleted of Tai.

Tai is required for formation of the Wg gradient.
Wg protein (greyscale) in (A-A”) control (en>GFP,RFP), (B-B”) Tai overexpressing, or (C-C”) Tai-depleted larval wing discs. enGal4 activity in the P-domain is marked by GFP. Arrows in B’ mark gaps in Wg DV stripe characteristic of Tai overexpression. Arrows in C’ mark the clear drop in total Wg on the DV flanks of P-domains depleted of Tai. A”-C” provide higher magnification views of regions in B’-C’. (D) Relative Wg fluorescence intensity of pouch cells below D/V boundary (to avoid Wg source cells) plotted from anterior to posterior. (E) Mean Wg relative fluorescence intensity plotted as a ratio of posterior to anterior intensity. RFP vs tai *p=0.0443, RFP vs tai^RNAi *p<0.0156 (Unpaired student t-test with Welch’s correction).

Tai controls Dally-like protein (Dlp) levels.
(A-C,F-G) Anti-Dlp staining (greyscale) in (A-A”) control (en>GFP,RFP), (B-B”) Tai overexpressing (en>tai,GFP), and (C-C”) Tai-depleted cells. Arrows in A’ mark Dlp exclusion from the DV boundary region. Overexpression of Dlp restores Wg in Tai-depleted cells (F-F’; see arrow in magnified view), but causes complete loss of the Wg DV stripe in Tai overexpressing disc regions (G-G’; see arrow in magnified view). (D) Relative Dlp fluorescence intensities of pouch regions below D/V boundary plotted from anterior to posterior. (E) Mean relative Dlp fluorescence intensity plotted as a ratio of posterior to anterior intensity. RFP vs tai *p=0.0008, RFP vs tai^RNAi*p=0.0002 (Unpaired student t-test with Welch’s correction).

Tai expression at the D/V boundary enables excessive Wg spread.
(A-C) Anti-Wg signal (greyscale) in (A-A’) control (bbg>RFP), (B-B’) Tai-overexpressing (bbg>tai), or Tai-depleted (C-C’) discs co-stained for nuclei (DAPI; blue). Dotted lines denote magnified views of Wg in A’-C’.

The tai^lowhypomorph causes Dlp intracellular accumulation in pouch cells.
(A-D) hsFlp generated tai^low clones (GFP negative) in a H99/+ background co-stained for Dlp (greyscale) and nuclei (DAPI; cyan). Discs in panels A-A” and C were permeabilized to detect total Dlp (intracellular and extracellular), while discs in panel B-B” were processed without permeabilization and only detect extracellular Dlp. Arrows in C and D denote tai^low cells in side-view with intracellular Dlp.

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