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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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Gradients/boundaries of Ft/Ds pathway gene expression modify the pkpk hair polarity phenotype.All micrographs show a detail of the A region of the female dorsal wing (red boxed region in (A)). Black arrows indicate local hair polarity. (A) Wing cartoon showing major expression domain of the sal-Gal4 driver (blue shading). (B) Wild-type (Oregon R). (C) pk30/pk30. (D) sal-Gal4/UAS-ds(IR). (E) pk30, UAS-ds(IR)/pk30, sal-Gal4. (F) sal-Gal4; UAS-ds. (G) pk30 sal-Gal4/pk30; UAS-ds. (H) sal-Gal4/UAS-ft(IR). (I) pk30, UAS-ft(IR)/pk30, sal-Gal4. (J) sal-Gal4/UAS-ft. (K) pk30, sal-Gal4/pk30, UAS-ft. (L) sal-Gal4/UAS-fj. (M) pk30, sal-Gal4/pk30, UAS-fj.
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pgen-1001305-g007: Gradients/boundaries of Ft/Ds pathway gene expression modify the pkpk hair polarity phenotype.All micrographs show a detail of the A region of the female dorsal wing (red boxed region in (A)). Black arrows indicate local hair polarity. (A) Wing cartoon showing major expression domain of the sal-Gal4 driver (blue shading). (B) Wild-type (Oregon R). (C) pk30/pk30. (D) sal-Gal4/UAS-ds(IR). (E) pk30, UAS-ds(IR)/pk30, sal-Gal4. (F) sal-Gal4; UAS-ds. (G) pk30 sal-Gal4/pk30; UAS-ds. (H) sal-Gal4/UAS-ft(IR). (I) pk30, UAS-ft(IR)/pk30, sal-Gal4. (J) sal-Gal4/UAS-ft. (K) pk30, sal-Gal4/pk30, UAS-ft. (L) sal-Gal4/UAS-fj. (M) pk30, sal-Gal4/pk30, UAS-fj.

Mentions: If gradients of Ft/Ds pathway gene activity control the direction of the Early Fz(Sple) signal, we would expect that altering local levels of Ft/Ds pathway gene expression in the pupal wing should reorient the Fz(Sple) signal. We initially generated marked clones of ft, ds and fj knockdown or over-expression in a pkpk mutant wing to identify hair polarity changes that result from inducing novel gradients/boundaries of Ft/Ds signaling. However, interpreting the effects of clones of variable shape, size and position on the pkpk mutant hair phenotype proved unfeasible. To overcome this problem, we used the well-characterized sal-Gal4 driver to drive localized over-expression or knockdown of ft, ds and fj in both wild-type and pkpk mutant wings. The sal-Gal4 driver expresses Gal4 protein in the spalt expression pattern [34] (i.e. between the L2 vein and midway between the L4 and L5 veins (Figure 7A)), and has been used successfully to generate gradients of Ft/Ds pathway gene expression along the A-P wing axis [27]. Using the sal-Gal4 driver to knockdown ds or ft, or to over-express ds, ft or fj resulted in changes in wing morphology, but did not affect hair polarity outside the main sal-Gal4 expression domain (see Figure 7D, 7F, 7H, 7J and 7L). However, when the same experiments were done in a pkpk mutant wing, specific changes of hair polarity were observed outside of the main sal-Gal4 expression domain. For example, in the A region of the wing (anterior to the L2 vein) hair polarity on a pkpk mutant wing is posterior (see Figure 4 and [12], [18], [21]). However, hair polarity in the A region of a pkpk mutant wing becomes anterior when sal-Gal4 is used to drive ds knockdown or ft or fj over-expression (Figure 7E, 7K and 7M). In contrast, pkpk mutant wings in which sal-Gal4 drives ds over-expression or ft knockdown retain posterior hair polarity in the A region. In each case, hair polarity within the main sal-Gal4 expression domain resembles the modified pkpk phenotype seen when the same Ft/Ds pathway genes were knockdown or over-expressed uniformly in the wing (see Figure 4 and Figure 5), with the exception of fj over-expression which maintained the normal pkpk mutant phenotype within the sal-Gal4 expression domain. This last observation is curious, but may be due to the relative levels of expression driven by the MS1096-Gal4 and sal-Gal4 drivers.


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)

Gradients/boundaries of Ft/Ds pathway gene expression modify the pkpk hair polarity phenotype.All micrographs show a detail of the A region of the female dorsal wing (red boxed region in (A)). Black arrows indicate local hair polarity. (A) Wing cartoon showing major expression domain of the sal-Gal4 driver (blue shading). (B) Wild-type (Oregon R). (C) pk30/pk30. (D) sal-Gal4/UAS-ds(IR). (E) pk30, UAS-ds(IR)/pk30, sal-Gal4. (F) sal-Gal4; UAS-ds. (G) pk30 sal-Gal4/pk30; UAS-ds. (H) sal-Gal4/UAS-ft(IR). (I) pk30, UAS-ft(IR)/pk30, sal-Gal4. (J) sal-Gal4/UAS-ft. (K) pk30, sal-Gal4/pk30, UAS-ft. (L) sal-Gal4/UAS-fj. (M) pk30, sal-Gal4/pk30, UAS-fj.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3040658&req=5

pgen-1001305-g007: Gradients/boundaries of Ft/Ds pathway gene expression modify the pkpk hair polarity phenotype.All micrographs show a detail of the A region of the female dorsal wing (red boxed region in (A)). Black arrows indicate local hair polarity. (A) Wing cartoon showing major expression domain of the sal-Gal4 driver (blue shading). (B) Wild-type (Oregon R). (C) pk30/pk30. (D) sal-Gal4/UAS-ds(IR). (E) pk30, UAS-ds(IR)/pk30, sal-Gal4. (F) sal-Gal4; UAS-ds. (G) pk30 sal-Gal4/pk30; UAS-ds. (H) sal-Gal4/UAS-ft(IR). (I) pk30, UAS-ft(IR)/pk30, sal-Gal4. (J) sal-Gal4/UAS-ft. (K) pk30, sal-Gal4/pk30, UAS-ft. (L) sal-Gal4/UAS-fj. (M) pk30, sal-Gal4/pk30, UAS-fj.
Mentions: If gradients of Ft/Ds pathway gene activity control the direction of the Early Fz(Sple) signal, we would expect that altering local levels of Ft/Ds pathway gene expression in the pupal wing should reorient the Fz(Sple) signal. We initially generated marked clones of ft, ds and fj knockdown or over-expression in a pkpk mutant wing to identify hair polarity changes that result from inducing novel gradients/boundaries of Ft/Ds signaling. However, interpreting the effects of clones of variable shape, size and position on the pkpk mutant hair phenotype proved unfeasible. To overcome this problem, we used the well-characterized sal-Gal4 driver to drive localized over-expression or knockdown of ft, ds and fj in both wild-type and pkpk mutant wings. The sal-Gal4 driver expresses Gal4 protein in the spalt expression pattern [34] (i.e. between the L2 vein and midway between the L4 and L5 veins (Figure 7A)), and has been used successfully to generate gradients of Ft/Ds pathway gene expression along the A-P wing axis [27]. Using the sal-Gal4 driver to knockdown ds or ft, or to over-express ds, ft or fj resulted in changes in wing morphology, but did not affect hair polarity outside the main sal-Gal4 expression domain (see Figure 7D, 7F, 7H, 7J and 7L). However, when the same experiments were done in a pkpk mutant wing, specific changes of hair polarity were observed outside of the main sal-Gal4 expression domain. For example, in the A region of the wing (anterior to the L2 vein) hair polarity on a pkpk mutant wing is posterior (see Figure 4 and [12], [18], [21]). However, hair polarity in the A region of a pkpk mutant wing becomes anterior when sal-Gal4 is used to drive ds knockdown or ft or fj over-expression (Figure 7E, 7K and 7M). In contrast, pkpk mutant wings in which sal-Gal4 drives ds over-expression or ft knockdown retain posterior hair polarity in the A region. In each case, hair polarity within the main sal-Gal4 expression domain resembles the modified pkpk phenotype seen when the same Ft/Ds pathway genes were knockdown or over-expressed uniformly in the wing (see Figure 4 and Figure 5), with the exception of fj over-expression which maintained the normal pkpk mutant phenotype within the sal-Gal4 expression domain. This last observation is curious, but may be due to the relative levels of expression driven by the MS1096-Gal4 and sal-Gal4 drivers.

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