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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 modifies the pkpk hair polarity phenotype.All micrographs are of the female dorsal wing surface. Arrows indicate local hair polarity, red arrows indicate where local hair polarity differs from that seen on a pkpk30 homozygous wing. (A) pkpk30 homozygous wing. (B) Detail of anterior pkpk30 homozygous wing (anterior yellow shaded region in (A)). (C) Detail of posterior pkpk30 homozygous wing (posterior yellow shaded region in (A)). (D) ft1, pkpk30 homozygous wing. (E) Detail of anterior ft1, pkpk30 homozygous wing (anterior yellow shaded region in (D)). (F) Detail of posterior ft1, pkpk30 homozygous wing (posterior yellow shaded region in (D)). (G) MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing. (H) Detail of anterior MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing (anterior yellow shaded region in (G)). (I) Detail of posterior MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing (posterior yellow shaded region in (G)). (J) lftTG2, pkpk30 homozygous wing. (K) Detail of anterior lftTG2, pkpk30 homozygous wing (anterior yellow shaded region in (J)). (I) Detail of posterior lftTG2, pkpk30 homozygous wing (posterior yellow shaded region in (J)).
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pgen-1001305-g004: Reduced Ft/Ds pathway gene activity modifies the pkpk hair polarity phenotype.All micrographs are of the female dorsal wing surface. Arrows indicate local hair polarity, red arrows indicate where local hair polarity differs from that seen on a pkpk30 homozygous wing. (A) pkpk30 homozygous wing. (B) Detail of anterior pkpk30 homozygous wing (anterior yellow shaded region in (A)). (C) Detail of posterior pkpk30 homozygous wing (posterior yellow shaded region in (A)). (D) ft1, pkpk30 homozygous wing. (E) Detail of anterior ft1, pkpk30 homozygous wing (anterior yellow shaded region in (D)). (F) Detail of posterior ft1, pkpk30 homozygous wing (posterior yellow shaded region in (D)). (G) MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing. (H) Detail of anterior MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing (anterior yellow shaded region in (G)). (I) Detail of posterior MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing (posterior yellow shaded region in (G)). (J) lftTG2, pkpk30 homozygous wing. (K) Detail of anterior lftTG2, pkpk30 homozygous wing (anterior yellow shaded region in (J)). (I) Detail of posterior lftTG2, pkpk30 homozygous wing (posterior yellow shaded region in (J)).

Mentions: Our analysis of wing ridge phenotypes led us to conclude that reduced Ft/Ds pathway activity can affect the direction of the Early Fz(Sple) signal without altering the Late Fz(Pk) signal. Since the Late Fz(Pk) signal is inactivated in a pkpk mutant wing, the pkpk hair polarity phenotype should reflect the direction of the Early Fz(Sple) signal [12]. Consequently, if reducing Ft/Ds pathway activity affects the orientation of the Early Fz(Sple) signal, we predict that it should significantly modify the pkpk mutant wing hair phenotype. This turns out to be the case. For example, although a ft1 homozygous wing has wild-type hair polarity, the pkpk30 hair polarity phenotype is substantially modified in a ft1, pkpk30 double mutant wing (compare Figure 4A with 4D). Specifically, in comparison to a pkpk30 homozygote, ft1, pkpk30 hair polarity is more distal in both the anterior wing (compare Figure 4B with 4E) and in distal regions of the posterior wing (compare Figure 4C with 4F). We see a similar modification of the pkpk hair phenotype when driving uniform ft RNAi expression (VDRC transformant 9396GD) in a pkpk mutant wing (MS1096-gal4; pk30, UAS-ft(IR)/pk30), but with more extensive regions of distal hair polarity in the posterior wing and an anterior component to anterior hair polarity (data not shown). Driving uniform expression of ds RNAi (VDRC transformant 36219GD) in the dorsal wing of a pkpk mutant also modifies the pkpk hair phenotype to a more distal polarity in the anterior and distal posterior wing (Figure 4G, 4H and 4I). We also generated flies homozygous for both a pkpk allele and for an amorphic allele of lowfat (lft), a recently identified modulator of Ft/Ds signaling [25]. lftTG2 homozygous wings display altered wing morphology and aberrant posterior ridges, but wild-type hair polarity ([25] and data not shown). In lftTG2, pkpk homozygous wings, the pkpk hair phenotype is modified to a more distal polarity in the anterior and distal posterior wing (Figure 4J, 4K and 4L), in a similar manner to when ft or ds activity is reduced. Hair polarity on fjD1, pkpk30 homozygous wings is also more distal than the pkpk30 phenotype. However, this effect is less than observed for reduced ft, ds or lft activity and appears region specific. For example, hair polarity in the A region (anterior to the L2 vein) of a fjD1, pkpk30 wing is entirely distal, but in the B region (between the L2 and L3 vein) retains a significant posterior component and so is closer to the pkpk30 phenotype (data not shown).


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 modifies the pkpk hair polarity phenotype.All micrographs are of the female dorsal wing surface. Arrows indicate local hair polarity, red arrows indicate where local hair polarity differs from that seen on a pkpk30 homozygous wing. (A) pkpk30 homozygous wing. (B) Detail of anterior pkpk30 homozygous wing (anterior yellow shaded region in (A)). (C) Detail of posterior pkpk30 homozygous wing (posterior yellow shaded region in (A)). (D) ft1, pkpk30 homozygous wing. (E) Detail of anterior ft1, pkpk30 homozygous wing (anterior yellow shaded region in (D)). (F) Detail of posterior ft1, pkpk30 homozygous wing (posterior yellow shaded region in (D)). (G) MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing. (H) Detail of anterior MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing (anterior yellow shaded region in (G)). (I) Detail of posterior MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing (posterior yellow shaded region in (G)). (J) lftTG2, pkpk30 homozygous wing. (K) Detail of anterior lftTG2, pkpk30 homozygous wing (anterior yellow shaded region in (J)). (I) Detail of posterior lftTG2, pkpk30 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-g004: Reduced Ft/Ds pathway gene activity modifies the pkpk hair polarity phenotype.All micrographs are of the female dorsal wing surface. Arrows indicate local hair polarity, red arrows indicate where local hair polarity differs from that seen on a pkpk30 homozygous wing. (A) pkpk30 homozygous wing. (B) Detail of anterior pkpk30 homozygous wing (anterior yellow shaded region in (A)). (C) Detail of posterior pkpk30 homozygous wing (posterior yellow shaded region in (A)). (D) ft1, pkpk30 homozygous wing. (E) Detail of anterior ft1, pkpk30 homozygous wing (anterior yellow shaded region in (D)). (F) Detail of posterior ft1, pkpk30 homozygous wing (posterior yellow shaded region in (D)). (G) MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing. (H) Detail of anterior MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing (anterior yellow shaded region in (G)). (I) Detail of posterior MS1096-gal4; UAS-ds(IR), pkpk30/pkpk30 wing (posterior yellow shaded region in (G)). (J) lftTG2, pkpk30 homozygous wing. (K) Detail of anterior lftTG2, pkpk30 homozygous wing (anterior yellow shaded region in (J)). (I) Detail of posterior lftTG2, pkpk30 homozygous wing (posterior yellow shaded region in (J)).
Mentions: Our analysis of wing ridge phenotypes led us to conclude that reduced Ft/Ds pathway activity can affect the direction of the Early Fz(Sple) signal without altering the Late Fz(Pk) signal. Since the Late Fz(Pk) signal is inactivated in a pkpk mutant wing, the pkpk hair polarity phenotype should reflect the direction of the Early Fz(Sple) signal [12]. Consequently, if reducing Ft/Ds pathway activity affects the orientation of the Early Fz(Sple) signal, we predict that it should significantly modify the pkpk mutant wing hair phenotype. This turns out to be the case. For example, although a ft1 homozygous wing has wild-type hair polarity, the pkpk30 hair polarity phenotype is substantially modified in a ft1, pkpk30 double mutant wing (compare Figure 4A with 4D). Specifically, in comparison to a pkpk30 homozygote, ft1, pkpk30 hair polarity is more distal in both the anterior wing (compare Figure 4B with 4E) and in distal regions of the posterior wing (compare Figure 4C with 4F). We see a similar modification of the pkpk hair phenotype when driving uniform ft RNAi expression (VDRC transformant 9396GD) in a pkpk mutant wing (MS1096-gal4; pk30, UAS-ft(IR)/pk30), but with more extensive regions of distal hair polarity in the posterior wing and an anterior component to anterior hair polarity (data not shown). Driving uniform expression of ds RNAi (VDRC transformant 36219GD) in the dorsal wing of a pkpk mutant also modifies the pkpk hair phenotype to a more distal polarity in the anterior and distal posterior wing (Figure 4G, 4H and 4I). We also generated flies homozygous for both a pkpk allele and for an amorphic allele of lowfat (lft), a recently identified modulator of Ft/Ds signaling [25]. lftTG2 homozygous wings display altered wing morphology and aberrant posterior ridges, but wild-type hair polarity ([25] and data not shown). In lftTG2, pkpk homozygous wings, the pkpk hair phenotype is modified to a more distal polarity in the anterior and distal posterior wing (Figure 4J, 4K and 4L), in a similar manner to when ft or ds activity is reduced. Hair polarity on fjD1, pkpk30 homozygous wings is also more distal than the pkpk30 phenotype. However, this effect is less than observed for reduced ft, ds or lft activity and appears region specific. For example, hair polarity in the A region (anterior to the L2 vein) of a fjD1, pkpk30 wing is entirely distal, but in the B region (between the L2 and L3 vein) retains a significant posterior component and so is closer to the pkpk30 phenotype (data not shown).

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