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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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Reduced Ft/Ds pathway gene activity alters posterior ridge orientation without affecting hair polarity.All micrographs are of the female dorsal wing surface. Black arrows indicate local hair polarity; red lines indicate local ridge orientation. Panels B, C, E, F, H, I, K and L show light micrographs of hair polarity overlaid on an inverted and colorized (red) CRM image of ridge orientation in the same region. (A) Wild-type (Canton S) wing. (B) Detail of anterior wild-type wing (anterior yellow shaded region in (A)). (C) Detail of posterior wild-type wing (posterior yellow shaded region in (A)). (D) ft1 homozygous wing. (E) Detail of anterior ft1 homozygous wing (anterior yellow shaded region in (D)). (F) Detail of posterior ft1 homozygous wing (posterior yellow shaded region in (D)). (G) MS109-Gal4; UAS-ds(IR) wing. (H) Detail of anterior MS109-Gal4; UAS-ds(IR) wing (anterior yellow shaded region in (G)). (I) Detail of posterior MS109-Gal4; UAS-ds(IR) wing (posterior yellow shaded region in (G)). (J) fjD1 homozygous wing. (K) Detail of anterior fjD1 homozygous wing (anterior yellow shaded region in (J)). (L) Detail of posterior fjD1 homozygous wing (posterior yellow shaded region in (J)).
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pgen-1001305-g003: Reduced Ft/Ds pathway gene activity alters posterior ridge orientation without affecting hair polarity.All micrographs are of the female dorsal wing surface. Black arrows indicate local hair polarity; red lines indicate local ridge orientation. Panels B, C, E, F, H, I, K and L show light micrographs of hair polarity overlaid on an inverted and colorized (red) CRM image of ridge orientation in the same region. (A) Wild-type (Canton S) wing. (B) Detail of anterior wild-type wing (anterior yellow shaded region in (A)). (C) Detail of posterior wild-type wing (posterior yellow shaded region in (A)). (D) ft1 homozygous wing. (E) Detail of anterior ft1 homozygous wing (anterior yellow shaded region in (D)). (F) Detail of posterior ft1 homozygous wing (posterior yellow shaded region in (D)). (G) MS109-Gal4; UAS-ds(IR) wing. (H) Detail of anterior MS109-Gal4; UAS-ds(IR) wing (anterior yellow shaded region in (G)). (I) Detail of posterior MS109-Gal4; UAS-ds(IR) wing (posterior yellow shaded region in (G)). (J) fjD1 homozygous wing. (K) Detail of anterior fjD1 homozygous wing (anterior yellow shaded region in (J)). (L) Detail of posterior fjD1 homozygous wing (posterior yellow shaded region in (J)).

Mentions: Membrane ridge orientation differs between the anterior and posterior of the wild-type Drosophila wing [12]. The boundary between these two regions lies in the vicinity of the L3 vein, but is not possible to pinpoint on wild-type wings, as ridge orientation is difficult to determine adjacent to wing veins. Homozygous rhove-1, vn1 wings lack wing veins L2-5 and display altered wing shape [19]. Using our Cuticle Refraction Microscopy (CRM) technique [12] in conjunction with conventional light microscopy, we find that rhove-1, vn1 wings retain wild-type hair polarity and ridge orientation (compare Figure 2A with Figure 3A). In the absence of veins on the rhove-1, vn1 wing, it becomes clear that the boundary between anterior A-P and posterior P-D ridge orientation can be mapped to a narrow region, about 2–3 cells wide, that forms an approximately straight line along the P-D axis of the wing (yellow shaded region in Figure 2A and 2B). Our ability to finely map this region implies an abrupt change in PCP on the wing and for this reason we refer to it as a ‘PCP Discontinuity’ (PCP-D). The absence of veins and unusual wing morphology of the rhove-1, vn1 wing make the location of the PCP-D difficult to pinpoint. To overcome this problem, we over-expressed Argos uniformly during dorsal wing development (MS1096-gal4; UAS-argos). The Argos protein is a negative regulator of EGF signaling and Argos over-expression in the dorsal wing antagonizes longitudinal vein development resulting in variable loss of dorsal longitudinal veins including L3 (Figure 2C and [20]). These wings reveal that the discontinuity in ridge orientation (i.e. the PCP-D) maps to the normal location of the L3 vein (Figure 2D).


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)

Reduced Ft/Ds pathway gene activity alters posterior ridge orientation without affecting hair polarity.All micrographs are of the female dorsal wing surface. Black arrows indicate local hair polarity; red lines indicate local ridge orientation. Panels B, C, E, F, H, I, K and L show light micrographs of hair polarity overlaid on an inverted and colorized (red) CRM image of ridge orientation in the same region. (A) Wild-type (Canton S) wing. (B) Detail of anterior wild-type wing (anterior yellow shaded region in (A)). (C) Detail of posterior wild-type wing (posterior yellow shaded region in (A)). (D) ft1 homozygous wing. (E) Detail of anterior ft1 homozygous wing (anterior yellow shaded region in (D)). (F) Detail of posterior ft1 homozygous wing (posterior yellow shaded region in (D)). (G) MS109-Gal4; UAS-ds(IR) wing. (H) Detail of anterior MS109-Gal4; UAS-ds(IR) wing (anterior yellow shaded region in (G)). (I) Detail of posterior MS109-Gal4; UAS-ds(IR) wing (posterior yellow shaded region in (G)). (J) fjD1 homozygous wing. (K) Detail of anterior fjD1 homozygous wing (anterior yellow shaded region in (J)). (L) Detail of posterior fjD1 homozygous wing (posterior yellow shaded region in (J)).
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3040658&req=5

pgen-1001305-g003: Reduced Ft/Ds pathway gene activity alters posterior ridge orientation without affecting hair polarity.All micrographs are of the female dorsal wing surface. Black arrows indicate local hair polarity; red lines indicate local ridge orientation. Panels B, C, E, F, H, I, K and L show light micrographs of hair polarity overlaid on an inverted and colorized (red) CRM image of ridge orientation in the same region. (A) Wild-type (Canton S) wing. (B) Detail of anterior wild-type wing (anterior yellow shaded region in (A)). (C) Detail of posterior wild-type wing (posterior yellow shaded region in (A)). (D) ft1 homozygous wing. (E) Detail of anterior ft1 homozygous wing (anterior yellow shaded region in (D)). (F) Detail of posterior ft1 homozygous wing (posterior yellow shaded region in (D)). (G) MS109-Gal4; UAS-ds(IR) wing. (H) Detail of anterior MS109-Gal4; UAS-ds(IR) wing (anterior yellow shaded region in (G)). (I) Detail of posterior MS109-Gal4; UAS-ds(IR) wing (posterior yellow shaded region in (G)). (J) fjD1 homozygous wing. (K) Detail of anterior fjD1 homozygous wing (anterior yellow shaded region in (J)). (L) Detail of posterior fjD1 homozygous wing (posterior yellow shaded region in (J)).
Mentions: Membrane ridge orientation differs between the anterior and posterior of the wild-type Drosophila wing [12]. The boundary between these two regions lies in the vicinity of the L3 vein, but is not possible to pinpoint on wild-type wings, as ridge orientation is difficult to determine adjacent to wing veins. Homozygous rhove-1, vn1 wings lack wing veins L2-5 and display altered wing shape [19]. Using our Cuticle Refraction Microscopy (CRM) technique [12] in conjunction with conventional light microscopy, we find that rhove-1, vn1 wings retain wild-type hair polarity and ridge orientation (compare Figure 2A with Figure 3A). In the absence of veins on the rhove-1, vn1 wing, it becomes clear that the boundary between anterior A-P and posterior P-D ridge orientation can be mapped to a narrow region, about 2–3 cells wide, that forms an approximately straight line along the P-D axis of the wing (yellow shaded region in Figure 2A and 2B). Our ability to finely map this region implies an abrupt change in PCP on the wing and for this reason we refer to it as a ‘PCP Discontinuity’ (PCP-D). The absence of veins and unusual wing morphology of the rhove-1, vn1 wing make the location of the PCP-D difficult to pinpoint. To overcome this problem, we over-expressed Argos uniformly during dorsal wing development (MS1096-gal4; UAS-argos). The Argos protein is a negative regulator of EGF signaling and Argos over-expression in the dorsal wing antagonizes longitudinal vein development resulting in variable loss of dorsal longitudinal veins including L3 (Figure 2C and [20]). These wings reveal that the discontinuity in ridge orientation (i.e. the PCP-D) maps to the normal location of the L3 vein (Figure 2D).

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