Fig. 4

Fig. 4 Arl13b is required for the ciliogenic transcription factors, FoxJ1 and Rfx to promote ciliary length increase. (A) Primary cilia on somitic cells were lengthened in transgenic zebrafish embryos that overexpressed FoxJ1 or Rfx2. The embryos were analyzed at 18 hpf. (B) Quantitation of ciliary length increase in embryos that overexpressed FoxJ1 or Rfx2. Eight embryos were analyzed for each group, 50 cilia from each embryo. (C) Upregulation of arl13b mRNA levels after overexpression of FoxJ1 or Rfx2, a-actin mRNA served as loading control. (D) Quantification of arl13b mRNA up-regulation in response to overexpression of FoxJ1 or Rfx2 by qPCR from two individual experiments. (E) Knockdown of Arl13b abrogated primary cilia length increase by Rfx2 overexpression. Primary cilia in somitic cells of 18 hpf embryos are shown. (F) Knockdown of Arl13b abrogated increase of motile cilia length by FoxJ1. Motile cilia in the pronephric (kidney) duct of 24 hpf embryos are shown. (G) Quantitation of ciliary length alterations depicted in E. Eight embryos were analyzed from each group, 50 cilia from each embryo. Ciliary axonemes were stained with anti-acetylated tubulin antibodies (red). The green cytoplasmic staining is fluorescence of GFP expressed from an IRES element in the heat shock rfx2 and foxJ1 transgenes.