Uni-directional ciliary membrane protein trafficking by a cytoplasmic retrograde IFT motor and ciliary ectosome shedding

The role of the primary cilium in key signaling pathways depends on dynamic regulation of ciliary membrane protein composition, yet we know little about the motors or membrane events that regulate ciliary membrane protein trafficking in existing organelles. Recently, we showed that cilium-generated signaling in Chlamydomonas induced rapid, anterograde IFT-independent, cytoplasmic microtubule-dependent redistribution of the membrane polypeptide, SAG1-C65, from the plasma membrane to the periciliary region and the ciliary membrane. Here, we report that the retrograde IFT motor, cytoplasmic dynein 1b, is required in the cytoplasm for this rapid redistribution. Furthermore, signaling-induced trafficking of SAG1-C65 into cilia is unidirectional and the entire complement of cellular SAG1-C65 is shed during signaling and can be recovered in the form of ciliary ectosomes that retain signal-inducing activity. Thus, during signaling, cells regulate ciliary membrane protein composition through cytoplasmic action of the retrograde IFT motor and shedding of ciliary ectosomes

Supplementary Material for: Wnt5a Is Necessary for Normal Kidney Development in Zebrafish and Mice

<p><b><i>Background:</i></b> Wnt5a is important for the development of various organs and postnatal cellular function. Little is known, however, about the role of <i>Wnt5a</i> in kidney development, although <i>WNT5A</i> mutations were identified in patients with Robinow syndrome, a genetic disease which includes developmental defects in kidneys. Our goal in this study was to determine the role of <i>Wnt5a</i> in kidney development. <b><i>Methods:</i></b> Whole-mount in situ hybridization was used to establish the expression pattern of <i>Wnt5a</i> during kidney development. Zebrafish with <i>wnt5a</i> knockdown and <i>Wnt5a</i> global knockout mice were used to identify kidney phenotypes. <b><i>Results:</i></b> In zebrafish, <i>wnt5a</i> knockdown resulted in glomerular cyst formation and dilated renal tubules. In mice, <i>Wnt5a</i> global knockout resulted in pleiotropic, but severe, kidney phenotypes, including agenesis, fused kidney, hydronephrosis and duplex kidney/ureter. <b><i>Conclusions:</i></b> Our data demonstrated the important role of <i>Wnt5a</i> in kidney development. Disrupted Wnt5a resulted in kidney cysts in zebrafish and pleiotropic abnormal kidney development in mice.</p

Characterization of a Dchs1 mutant mouse reveals requirements for Dchs1-Fat4 signaling during mammalian development

The Drosophila Dachsous and Fat proteins function as ligand and receptor, respectively, for an intercellular signaling pathway that regulates Hippo signaling and planar cell polarity. Although gene-targeted mutations in two mammalian Fat genes have been described, whether mammals have a Fat signaling pathway equivalent to that in Drosophila, and what its biological functions might be, have remained unclear. Here, we describe a gene-targeted mutation in a murine Dachsous homolog, Dchs1. Analysis of the phenotypes of Dchs1 mutant mice and comparisons with Fat4 mutant mice identify requirements for these genes in multiple organs, including the ear, kidney, skeleton, intestine, heart and lung. Dchs1 and Fat4 single mutants and Dchs1 Fat4 double mutants have similar phenotypes throughout the body. In some cases, these phenotypes suggest that Dchs1-Fat4 signaling influences planar cell polarity. In addition to the appearance of cysts in newborn kidneys, we also identify and characterize a requirement for Dchs1 and Fat4 in growth, branching and cell survival during early kidney development. Dchs1 and Fat4 are predominantly expressed in mesenchymal cells in multiple organs, and mutation of either gene increases protein staining for the other. Our analysis implies that Dchs1 and Fat4 function as a ligand-receptor pair during murine development, and identifies novel requirements for Dchs1-Fat4 signaling in multiple organs