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WNT5 interacts with the Ryk receptors doughnut and derailed to mediate muscle attachment site selection in Drosophila melanogaster.

Lahaye LL, Wouda RR, de Jong AW, Fradkin LG, Noordermeer JN - PLoS ONE (2012)

Bottom Line: DRL belongs to the conserved Ryk receptor tyrosine kinase family which includes two other Drosophila orthologs, the Doughnut on 2 (DNT) and Derailed-2 (DRL-2) proteins.We generated a mutant allele of dnt and find that dnt, but not Drl-2, mutant embryos also show a muscle bypass phenotype.Genetic interaction experiments indicate that drl and dnt act together, likely as WNT5 receptors, to control muscle attachment site selection.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Developmental Neurobiology, Department of Molecular and Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.

ABSTRACT
In recent years a number of the genes that regulate muscle formation and maintenance in higher organisms have been identified. Studies employing invertebrate and vertebrate model organisms have revealed that many of the genes required for early mesoderm specification are highly conserved throughout evolution. Less is known about the molecules that mediate the steps subsequent to myogenesis, e. g. myotube guidance and attachment to tendon cells. We use the stereotypic pattern of the Drosophila embryonic body wall musculature in genetic approaches to identify novel factors required for muscle attachment site selection. Here, we show that Wnt5 is needed in this process. The lateral transverse muscles frequently overshoot their target attachment sites and stably attach at novel epidermal sites in Wnt5 mutant embryos. Restoration of WNT5 expression in either the muscle or the tendon cell rescues the mutant phenotype. Surprisingly, the novel attachment sites in Wnt5 mutants frequently do not express the Stripe (SR) protein which has been shown to be required for terminal tendon cell differentiation. A muscle bypass phenotype was previously reported for embryos lacking the WNT5 receptor Derailed (DRL). drl and Wnt5 mutant embryos also exhibit axon path finding errors. DRL belongs to the conserved Ryk receptor tyrosine kinase family which includes two other Drosophila orthologs, the Doughnut on 2 (DNT) and Derailed-2 (DRL-2) proteins. We generated a mutant allele of dnt and find that dnt, but not Drl-2, mutant embryos also show a muscle bypass phenotype. Genetic interaction experiments indicate that drl and dnt act together, likely as WNT5 receptors, to control muscle attachment site selection. These results extend previous findings that at least some of the molecular pathways that guide axons towards their targets are also employed for guidance of muscle fibers to their appropriate attachment sites.

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The new attachment sites of the bypassed muscle fibers in Wnt5 and drl mutants express βPS integrin.Wild type (A), Wnt5400 (B) and drlred2 (C) embryos were labelled with anti-βPS Integrin. Muscles 21–23 do exhibit an accumulation of βPS Integrin protein at the tip of the overshooting fibers (white asterix).
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pone-0032297-g007: The new attachment sites of the bypassed muscle fibers in Wnt5 and drl mutants express βPS integrin.Wild type (A), Wnt5400 (B) and drlred2 (C) embryos were labelled with anti-βPS Integrin. Muscles 21–23 do exhibit an accumulation of βPS Integrin protein at the tip of the overshooting fibers (white asterix).

Mentions: We confirmed these results by examining embryos of the genotypes Wnt5400; UAS-Tau-MYC/sr-GAL4 and drlRed2; UAS-Tau-MYC/sr-GAL4 for Myc and Muscle Myosin expression (Figs. 6D–F). We conclude that the presence of the SR protein in the bypassed tendon cell indicates that overshooting by the muscle fiber is a result of a defect of muscle guidance in drl and Wnt5 mutant embryos, rather than due to alterations in the fate or formation of the appropriate tendon cell. βPS integrin, a protein associated with the myotendinous junction formed at the end of tendon cell determination, accumulates at the tip of the overshooting muscle in the Wnt5 and drl mutant embryos (Fig. 7).


WNT5 interacts with the Ryk receptors doughnut and derailed to mediate muscle attachment site selection in Drosophila melanogaster.

Lahaye LL, Wouda RR, de Jong AW, Fradkin LG, Noordermeer JN - PLoS ONE (2012)

The new attachment sites of the bypassed muscle fibers in Wnt5 and drl mutants express βPS integrin.Wild type (A), Wnt5400 (B) and drlred2 (C) embryos were labelled with anti-βPS Integrin. Muscles 21–23 do exhibit an accumulation of βPS Integrin protein at the tip of the overshooting fibers (white asterix).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3293800&req=5

pone-0032297-g007: The new attachment sites of the bypassed muscle fibers in Wnt5 and drl mutants express βPS integrin.Wild type (A), Wnt5400 (B) and drlred2 (C) embryos were labelled with anti-βPS Integrin. Muscles 21–23 do exhibit an accumulation of βPS Integrin protein at the tip of the overshooting fibers (white asterix).
Mentions: We confirmed these results by examining embryos of the genotypes Wnt5400; UAS-Tau-MYC/sr-GAL4 and drlRed2; UAS-Tau-MYC/sr-GAL4 for Myc and Muscle Myosin expression (Figs. 6D–F). We conclude that the presence of the SR protein in the bypassed tendon cell indicates that overshooting by the muscle fiber is a result of a defect of muscle guidance in drl and Wnt5 mutant embryos, rather than due to alterations in the fate or formation of the appropriate tendon cell. βPS integrin, a protein associated with the myotendinous junction formed at the end of tendon cell determination, accumulates at the tip of the overshooting muscle in the Wnt5 and drl mutant embryos (Fig. 7).

Bottom Line: DRL belongs to the conserved Ryk receptor tyrosine kinase family which includes two other Drosophila orthologs, the Doughnut on 2 (DNT) and Derailed-2 (DRL-2) proteins.We generated a mutant allele of dnt and find that dnt, but not Drl-2, mutant embryos also show a muscle bypass phenotype.Genetic interaction experiments indicate that drl and dnt act together, likely as WNT5 receptors, to control muscle attachment site selection.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Developmental Neurobiology, Department of Molecular and Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.

ABSTRACT
In recent years a number of the genes that regulate muscle formation and maintenance in higher organisms have been identified. Studies employing invertebrate and vertebrate model organisms have revealed that many of the genes required for early mesoderm specification are highly conserved throughout evolution. Less is known about the molecules that mediate the steps subsequent to myogenesis, e. g. myotube guidance and attachment to tendon cells. We use the stereotypic pattern of the Drosophila embryonic body wall musculature in genetic approaches to identify novel factors required for muscle attachment site selection. Here, we show that Wnt5 is needed in this process. The lateral transverse muscles frequently overshoot their target attachment sites and stably attach at novel epidermal sites in Wnt5 mutant embryos. Restoration of WNT5 expression in either the muscle or the tendon cell rescues the mutant phenotype. Surprisingly, the novel attachment sites in Wnt5 mutants frequently do not express the Stripe (SR) protein which has been shown to be required for terminal tendon cell differentiation. A muscle bypass phenotype was previously reported for embryos lacking the WNT5 receptor Derailed (DRL). drl and Wnt5 mutant embryos also exhibit axon path finding errors. DRL belongs to the conserved Ryk receptor tyrosine kinase family which includes two other Drosophila orthologs, the Doughnut on 2 (DNT) and Derailed-2 (DRL-2) proteins. We generated a mutant allele of dnt and find that dnt, but not Drl-2, mutant embryos also show a muscle bypass phenotype. Genetic interaction experiments indicate that drl and dnt act together, likely as WNT5 receptors, to control muscle attachment site selection. These results extend previous findings that at least some of the molecular pathways that guide axons towards their targets are also employed for guidance of muscle fibers to their appropriate attachment sites.

Show MeSH
Related in: MedlinePlus