title: Contribution of hedgehog signaling to the establishment of left-right asymmetry in the sea urchin.
abstract: Most bilaterians exhibit a left-right asymmetric distribution of their internal organs. The sea urchin larva is notable in this regard since most adult structures are generated from left sided embryonic structures. The gene regulatory network governing this larval asymmetry is still a work in progress but involves several conserved signaling pathways including Nodal, and BMP. Here we provide a comprehensive analysis of Hedgehog signaling and it's contribution to left-right asymmetry. We report that Hh signaling plays a conserved role to regulate late asymmetric expression of Nodal and that this regulation occurs after Nodal breaks left-right symmetry in the mesoderm. Thus, while Hh functions to maintain late Nodal expression, the molecular asymmetry of the future coelomic pouches is locked in. Furthermore we report that cilia play a role only insofar as to transduce Hh signaling and do not have an independent effect on the asymmetry of the mesoderm. From this, we are able to construct a more complete regulatory network governing the establishment of left-right asymmetry in the sea urchin.
authors.affiliation: Duke University Department of Biology, Durham, NC, United States.
authors.forename: Jacob F
authors.initials: JF
authors.lastname: Warner
authors.affiliation: Duke University Department of Biology, Durham, NC, United States.
authors.forename: Esther L
authors.initials: EL
authors.lastname: Miranda
authors.affiliation: Duke University Department of Biology, Durham, NC, United States. Electronic address: dmcclay@duke.edu.
authors.forename: David R
authors.initials: DR
authors.lastname: McClay
mesh_terms: D000818:Animals; D019521:Body Patterning; D002923:Cilia / Q000502:physiology; D004625:Embryo, Nonmammalian / Q000378:metabolism; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D053823:Hedgehog Proteins / Q000502:physiology*; D017403:In Situ Hybridization; D016547:Kinesins / Q000737:chemistry; D008648:Mesoderm / Q000378:metabolism; D055457:Nodal Protein / Q000502:physiology; D016376:Oligonucleotides, Antisense / Q000235:genetics; D016133:Polymerase Chain Reaction; D012617:Sea Urchins / Q000196:embryology* / Q000502:physiology*; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D053823:Hedgehog Proteins; D055457:Nodal Protein; D016376:Oligonucleotides, Antisense; D016212:Transforming Growth Factor beta; C074152:kinesin-II; D016547:Kinesins
keywords: Cilia; Hedgehog; Nodal; Right–left asymmetry; Sea urchin