Limits...
Two frizzled planar cell polarity signals in the Drosophila wing are differentially organized by the Fat/Dachsous pathway.

Hogan J, Valentine M, Cox C, Doyle K, Collier S - PLoS Genet. (2011)

Bottom Line: There is strong evidence that the Fz PCP pathway signals twice during wing development, and we have previously presented a Bidirectional-Biphasic Fz PCP signaling model which proposes that the Early and Late Fz PCP signals are in different directions and employ different isoforms of the Prickle protein.The goal of this study was to investigate the role of the Ft/Ds pathway in the context of our Fz PCP signaling model.Our results allow us to draw the following conclusions: (1) The Early Fz PCP signals are in opposing directions in the anterior and posterior wing and converge precisely at the site of the L3 wing vein. (2) Increased or decreased expression of Ft/Ds pathway genes can alter the direction of the Early Fz PCP signal without affecting the Late Fz PCP signal. (3) Lowfat, a Ft/Ds pathway regulator, is required for the normal orientation of the Early Fz PCP signal but not the Late Fz PCP signal. (4) At the time of the Early Fz PCP signal there are symmetric gradients of dachsous (ds) expression centered on the L3 wing vein, suggesting Ds activity gradients may orient the Fz signal. (5) Localized knockdown or over-expression of Ft/Ds pathway genes shows that boundaries/gradients of Ft/Ds pathway gene expression can redirect the Early Fz PCP signal specifically. (6) Altering the timing of ds knockdown during wing development can separate the role of the Ft/Ds pathway in wing morphogenesis from its role in Early Fz PCP signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Marshall University, Huntington, West Virginia, United States of America.

ABSTRACT
The regular array of distally pointing hairs on the mature Drosophila wing is evidence for the fine control of Planar Cell Polarity (PCP) during wing development. Normal wing PCP requires both the Frizzled (Fz) PCP pathway and the Fat/Dachsous (Ft/Ds) pathway, although the functional relationship between these pathways remains under debate. There is strong evidence that the Fz PCP pathway signals twice during wing development, and we have previously presented a Bidirectional-Biphasic Fz PCP signaling model which proposes that the Early and Late Fz PCP signals are in different directions and employ different isoforms of the Prickle protein. The goal of this study was to investigate the role of the Ft/Ds pathway in the context of our Fz PCP signaling model. Our results allow us to draw the following conclusions: (1) The Early Fz PCP signals are in opposing directions in the anterior and posterior wing and converge precisely at the site of the L3 wing vein. (2) Increased or decreased expression of Ft/Ds pathway genes can alter the direction of the Early Fz PCP signal without affecting the Late Fz PCP signal. (3) Lowfat, a Ft/Ds pathway regulator, is required for the normal orientation of the Early Fz PCP signal but not the Late Fz PCP signal. (4) At the time of the Early Fz PCP signal there are symmetric gradients of dachsous (ds) expression centered on the L3 wing vein, suggesting Ds activity gradients may orient the Fz signal. (5) Localized knockdown or over-expression of Ft/Ds pathway genes shows that boundaries/gradients of Ft/Ds pathway gene expression can redirect the Early Fz PCP signal specifically. (6) Altering the timing of ds knockdown during wing development can separate the role of the Ft/Ds pathway in wing morphogenesis from its role in Early Fz PCP signaling.

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Symmetric ds expression gradients are centered on the L3 vein at 18 hours a.p.f.(A) An 18 hour ds-lacZ pupal wing stained for beta-galactosidase activity (blue). The dashed black line represents the approximate outline of the wing. Red arrows define the distal limit of beta-galactosidase activity on the dorsal and ventral epithelia. (B) Wing from a newly eclosed en-gal4, UAS-gfp fly showing GFP fluorescence (green) in the posterior wing. (C) An 18 hour ds-lacZ/en-gal4, UAS-gfp pupal wing stained for beta-galactosidase activity (blue). Note that this wing has been stained for a shorter period than the wing in (A) in order to identify just the highest levels of enzyme activity (indicated by red arrowhead). (D) Same image as (C) overlaid with a color-inverted and falsely colored (green) image of GFP staining in the same wing.
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pgen-1001305-g006: Symmetric ds expression gradients are centered on the L3 vein at 18 hours a.p.f.(A) An 18 hour ds-lacZ pupal wing stained for beta-galactosidase activity (blue). The dashed black line represents the approximate outline of the wing. Red arrows define the distal limit of beta-galactosidase activity on the dorsal and ventral epithelia. (B) Wing from a newly eclosed en-gal4, UAS-gfp fly showing GFP fluorescence (green) in the posterior wing. (C) An 18 hour ds-lacZ/en-gal4, UAS-gfp pupal wing stained for beta-galactosidase activity (blue). Note that this wing has been stained for a shorter period than the wing in (A) in order to identify just the highest levels of enzyme activity (indicated by red arrowhead). (D) Same image as (C) overlaid with a color-inverted and falsely colored (green) image of GFP staining in the same wing.

Mentions: Conventionally, gradients of Ft/Ds activity, arising from localized expression of one or more Ft/Ds pathway genes, have been proposed to organize epithelial PCP [26]. In the wing, proximal Ds expression and distal Fj expression have been proposed to generate Ft/Ds activity gradients that organize hair polarity [6], [14], [27]. This proposal is supported by studies that show Ds expression is primarily in the proximal wing at 24–26 hours a.p.f., shortly before the Late Fz PCP signal [6], [27]. However, at 17 hours a.p.f., immediately before the Early Fz PCP signal [12], [14], Ds protein is present in a P-D stripe along the centre of the wing blade (see Figure 6H in [27]). We stained ds-lacZ wings at 18 hours a.p.f. and detected a corresponding stripe of beta-galactosidase activity that extends along the majority of the wing blade (Figure 6A). Beta-galactosidase activity reduces gradually both anterior and posterior to this stripe, suggesting symmetric gradients of ds expression along the A-P axis. To localize this ds expression, we stained for beta-galactosidase activity in an 18 hours a.p.f. ds-lacZ wing that also expressed Green Fluorescent Protein (GFP) under the control of the engrailed (en) promoter (en-gal4, UAS-gfp). The en promoter drives GFP expression throughout the posterior wing with a sharp anterior boundary 4–5 cells posterior to the L3 vein (Figure 6B). In ds-lacZ/en-gal4, UAS-gfp wings, the peak of beta-galactosidase activity (red arrowheads in Figure 6C and 6D) is located anterior to the anterior boundary of GFP expression (Figure 6D) implying that the peak of ds expression maps close to the site of the L3 vein.


Two frizzled planar cell polarity signals in the Drosophila wing are differentially organized by the Fat/Dachsous pathway.

Hogan J, Valentine M, Cox C, Doyle K, Collier S - PLoS Genet. (2011)

Symmetric ds expression gradients are centered on the L3 vein at 18 hours a.p.f.(A) An 18 hour ds-lacZ pupal wing stained for beta-galactosidase activity (blue). The dashed black line represents the approximate outline of the wing. Red arrows define the distal limit of beta-galactosidase activity on the dorsal and ventral epithelia. (B) Wing from a newly eclosed en-gal4, UAS-gfp fly showing GFP fluorescence (green) in the posterior wing. (C) An 18 hour ds-lacZ/en-gal4, UAS-gfp pupal wing stained for beta-galactosidase activity (blue). Note that this wing has been stained for a shorter period than the wing in (A) in order to identify just the highest levels of enzyme activity (indicated by red arrowhead). (D) Same image as (C) overlaid with a color-inverted and falsely colored (green) image of GFP staining in the same wing.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3040658&req=5

pgen-1001305-g006: Symmetric ds expression gradients are centered on the L3 vein at 18 hours a.p.f.(A) An 18 hour ds-lacZ pupal wing stained for beta-galactosidase activity (blue). The dashed black line represents the approximate outline of the wing. Red arrows define the distal limit of beta-galactosidase activity on the dorsal and ventral epithelia. (B) Wing from a newly eclosed en-gal4, UAS-gfp fly showing GFP fluorescence (green) in the posterior wing. (C) An 18 hour ds-lacZ/en-gal4, UAS-gfp pupal wing stained for beta-galactosidase activity (blue). Note that this wing has been stained for a shorter period than the wing in (A) in order to identify just the highest levels of enzyme activity (indicated by red arrowhead). (D) Same image as (C) overlaid with a color-inverted and falsely colored (green) image of GFP staining in the same wing.
Mentions: Conventionally, gradients of Ft/Ds activity, arising from localized expression of one or more Ft/Ds pathway genes, have been proposed to organize epithelial PCP [26]. In the wing, proximal Ds expression and distal Fj expression have been proposed to generate Ft/Ds activity gradients that organize hair polarity [6], [14], [27]. This proposal is supported by studies that show Ds expression is primarily in the proximal wing at 24–26 hours a.p.f., shortly before the Late Fz PCP signal [6], [27]. However, at 17 hours a.p.f., immediately before the Early Fz PCP signal [12], [14], Ds protein is present in a P-D stripe along the centre of the wing blade (see Figure 6H in [27]). We stained ds-lacZ wings at 18 hours a.p.f. and detected a corresponding stripe of beta-galactosidase activity that extends along the majority of the wing blade (Figure 6A). Beta-galactosidase activity reduces gradually both anterior and posterior to this stripe, suggesting symmetric gradients of ds expression along the A-P axis. To localize this ds expression, we stained for beta-galactosidase activity in an 18 hours a.p.f. ds-lacZ wing that also expressed Green Fluorescent Protein (GFP) under the control of the engrailed (en) promoter (en-gal4, UAS-gfp). The en promoter drives GFP expression throughout the posterior wing with a sharp anterior boundary 4–5 cells posterior to the L3 vein (Figure 6B). In ds-lacZ/en-gal4, UAS-gfp wings, the peak of beta-galactosidase activity (red arrowheads in Figure 6C and 6D) is located anterior to the anterior boundary of GFP expression (Figure 6D) implying that the peak of ds expression maps close to the site of the L3 vein.

Bottom Line: There is strong evidence that the Fz PCP pathway signals twice during wing development, and we have previously presented a Bidirectional-Biphasic Fz PCP signaling model which proposes that the Early and Late Fz PCP signals are in different directions and employ different isoforms of the Prickle protein.The goal of this study was to investigate the role of the Ft/Ds pathway in the context of our Fz PCP signaling model.Our results allow us to draw the following conclusions: (1) The Early Fz PCP signals are in opposing directions in the anterior and posterior wing and converge precisely at the site of the L3 wing vein. (2) Increased or decreased expression of Ft/Ds pathway genes can alter the direction of the Early Fz PCP signal without affecting the Late Fz PCP signal. (3) Lowfat, a Ft/Ds pathway regulator, is required for the normal orientation of the Early Fz PCP signal but not the Late Fz PCP signal. (4) At the time of the Early Fz PCP signal there are symmetric gradients of dachsous (ds) expression centered on the L3 wing vein, suggesting Ds activity gradients may orient the Fz signal. (5) Localized knockdown or over-expression of Ft/Ds pathway genes shows that boundaries/gradients of Ft/Ds pathway gene expression can redirect the Early Fz PCP signal specifically. (6) Altering the timing of ds knockdown during wing development can separate the role of the Ft/Ds pathway in wing morphogenesis from its role in Early Fz PCP signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Marshall University, Huntington, West Virginia, United States of America.

ABSTRACT
The regular array of distally pointing hairs on the mature Drosophila wing is evidence for the fine control of Planar Cell Polarity (PCP) during wing development. Normal wing PCP requires both the Frizzled (Fz) PCP pathway and the Fat/Dachsous (Ft/Ds) pathway, although the functional relationship between these pathways remains under debate. There is strong evidence that the Fz PCP pathway signals twice during wing development, and we have previously presented a Bidirectional-Biphasic Fz PCP signaling model which proposes that the Early and Late Fz PCP signals are in different directions and employ different isoforms of the Prickle protein. The goal of this study was to investigate the role of the Ft/Ds pathway in the context of our Fz PCP signaling model. Our results allow us to draw the following conclusions: (1) The Early Fz PCP signals are in opposing directions in the anterior and posterior wing and converge precisely at the site of the L3 wing vein. (2) Increased or decreased expression of Ft/Ds pathway genes can alter the direction of the Early Fz PCP signal without affecting the Late Fz PCP signal. (3) Lowfat, a Ft/Ds pathway regulator, is required for the normal orientation of the Early Fz PCP signal but not the Late Fz PCP signal. (4) At the time of the Early Fz PCP signal there are symmetric gradients of dachsous (ds) expression centered on the L3 wing vein, suggesting Ds activity gradients may orient the Fz signal. (5) Localized knockdown or over-expression of Ft/Ds pathway genes shows that boundaries/gradients of Ft/Ds pathway gene expression can redirect the Early Fz PCP signal specifically. (6) Altering the timing of ds knockdown during wing development can separate the role of the Ft/Ds pathway in wing morphogenesis from its role in Early Fz PCP signaling.

Show MeSH