The Balance Between the Novel Protein Target of Wingless and the Drosophila Rho-Associated Kinase Pathway Regulates Planar Cell Polarity in the Drosophila Wing

Department of Biology , University of Virginia, Charlottesville, Virginia, United States
Genetics (Impact Factor: 5.96). 07/2007; 176(2):891-903. DOI: 10.1534/genetics.106.069021
Source: PubMed


Planar cell polarity (PCP) signaling is mediated by the serpentine receptor Frizzled (Fz) and transduced by Dishevelled (Dsh). Wingless (Wg) signaling utilizes Drosophila Frizzled 2 (DFz2) as a receptor and also requires Dsh for transducing signals to regulate cell proliferation and differentiation in many developmental contexts. Distinct pathways are activated downstream of Dsh in Wg- and Fz-signaling pathways. Recently, a number of genes, which have essential roles as downstream components of PCP signaling, have been identified in Drosophila. They include the small GTPase RhoA/Rho1, its downstream effector Drosophila rho-associated kinase (Drok), and a number of genes such as inturned (in) and fuzzy (fy), whose biochemical functions are unclear. RhoA and Drok provide a link from Fz/Dsh signaling to the modulation of actin cytoskeleton. Here we report the identification of the novel gene target of wingless (tow) by enhancer trap screening. tow expression is negatively regulated by Wg signaling in wing imaginal discs, and the balance between tow and the Drok pathway regulates wing-hair morphogenesis. A loss-of-function mutation in tow does not result in a distinct phenotype. Genetic interaction and gain-of-function studies provide evidence that Tow acts downstream of Fz/Dsh and plays a role in restricting the number of hairs that wing cells form.

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Available from: Jeongbin Yim, Oct 28, 2015
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    • "Homologs of Tow have only been identified in insects [83] however; proteins with similar functions may exist in vertebrates. Tow is suppressed by wingless, and its over-expression causes planar cell polarity defects [83]. Thus at least in insects, Hh signaling appears to be suppressed by the Wnt pathway. "
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    • "Intriguingly, various data we have shown are at odds with previously published data concerning Tow. Neither by in situ hybridisation nor by Tow antibody staining have we ever observed a reliable expression pattern similar to the one shown by Chung et al. (2007) (where tow appears to be repressed by Wg signalling). We also saw no effect on Tow protein levels in discs where Wg signalling was reduced; by either ectopically expressed TCF Dominant negative (TCF- DN) or by reducing Wg secretion by expressing wntless RNAi (Supplementary Figs. "
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