title: Eliminating zebrafish pbx proteins reveals a hindbrain ground state.
abstract: The vertebrate hindbrain is divided into serially homologous segments, the rhombomeres (r). Pbx and Hox proteins are hypothesized to form heterodimeric, DNA binding transcription complexes which specify rhombomere identities. Here, we show that eliminating zebrafish Lzr/Pbx4 and Pbx2 function prevents hindbrain segmentation and causes a wholesale anterior homeotic transformation of r2-r6, to r1 identity. We demonstrate that Pbx proteins interact with Hox paralog group 1 proteins to specify segment identities broadly within the hindbrain, and that this process involves the Pbx:Hox-1-dependent induction of Fgf signals in r4. We propose that in the absence of Pbx function, r2-r6 acquire a homogeneous ground state identity, that of r1, and that Pbx proteins, functioning primarily with their Hox partners, function to modify this ground state identity during normal hindbrain development.
authors.affiliation: Howard Hughes Medical Institute, Division of Basic Science, Fred Hutchinson Cancer Research Center, P.O. Box 19024, 1100 Fairview Avenue North, Seattle, WA 98109, USA.
authors.forename: Andrew Jan
authors.initials: AJ
authors.lastname: Waskiewicz
authors.forename: Holly A
authors.initials: HA
authors.lastname: Rikhof
authors.forename: Cecilia B
authors.initials: CB
authors.lastname: Moens
mesh_terms: D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009030:Mosaicism; D009474:Neurons; D012249:Rhombencephalon / Q000196:embryology*; D015027:Zebrafish / Q000196:embryology / Q000235:genetics; D029961:Zebrafish Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C469732:Pbx2 protein, zebrafish; C486619:Pbx4 protein, zebrafish; D029961:Zebrafish Proteins