Xianwen Yu, Chee Peng Ng, Hermann Habacher & Sudipto Roy
Institute of Molecular and Cell Biology
Cancer and Developmental Cell Biology Division
Proteos, 61 Biopolis Drive
Correspondence should be addressed to S. R. (email@example.com)
Motile cilia induce fluid movement through their rhythmic beating activity. In mammals, the transcription factor Foxj1 has been implicated in motile cilia formation. Here, we show that a zebrafish Foxj1 homolog, foxj1a, is a novel target of Hedgehog signaling in the floor-plate. Loss of Foxj1a compromised the assembly of motile cilia which decorate floor-plate cells. Besides the floor-plate, foxj1a is expressed in the Kupffers’ vesicle and pronephric ducts, where it also promotes ciliary differentiation. We show that Foxj1a activates a constellation of genes essential for motile cilia formation and function, and that its activity is sufficient for ectopic development of cilia that resemble motile cilia. We also document that a paralogous gene, foxj1b, is expressed in the otic vesicle, and appears to regulate motile cilia formation in this tissue. Our findings identify a dedicated master regulatory role for Foxj1 in the transcriptional program that controls the production of motile cilia.
Figure Legend: (A) Expression of the foxj1 gene in the Kupffer’s vesicle (KV, arrow) of a gastrulating zebrafish embryo. The KV is a ciliated organ that functions like the mammalian node in specifying left-right asymmetry of visceral organs. (B) foxj1 expression in the developing kidney duct (short arrow) and the floor-plate of the spinal cord (long arrow) in an 18 hour post fertilization zebrafish embryo. (C) Ectopic cilium (arrow) that formed in response to mis-expression of Foxj1. Red = Acetylated tubulin; Green = Tektin-GFP; Blue = DAPI. Scale bar = 5 µm. (D) Tektin-GFP localization along the axoneme of the ectopic cilium (arrow). Green = Tektin-GFP; Blue = DAPI.
Published online: 16 November 2008 | doi:10.1038/ng.263.
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