Eliminating Zebrafish Pbx Proteins Reveals a Hindbrain Ground State

Waskiewicz, Andrew J.; Rikhof, Holly A.; Moens, Cecilia B.

doi:10.1016/s1534-5807(02)00319-2

Cited by 172 publications

(220 citation statements)

References 43 publications

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“…Multiple genes encoding this class of Hox-binding transcriptional cofactors have been identified in mouse and zebrafish (Popperl et al, 2000;Waskiewicz et al, 2002). Zebrafish pbx genes are expressed in broad overlapping domains, and pbx2 and pbx4 are expressed sufficiently early to play direct roles in generating rhombomere identities (Waskiewicz et al, 2002).…”

Section: Pbx Genesmentioning

confidence: 99%

“…Zebrafish pbx genes are expressed in broad overlapping domains, and pbx2 and pbx4 are expressed sufficiently early to play direct roles in generating rhombomere identities (Waskiewicz et al, 2002). In lazarus mutants deficient in pbx4 function (Popperl et al, 2000), r4 fails to develop normally and nVII BMNs exhibit a cell-autonomous failure to migrate caudally (Cooper et al, 2003), a phenotype that is identical to that of embryos deficient in the function of a binding partner Hoxb1a (McClintock et al, 2002;see above).…”

Section: Pbx Genesmentioning

confidence: 99%

“…Furthermore, nV motor axons frequently exit from r4 (a non-cell autonomous effect), consistent with an effect on the identities of r2 and r3 (Cooper et al, 2003; see mouse Hoxa2 phenotype above). When all maternal and zygotic pbx function is removed through an elegant combination of genetics and antisense morpholino treatment, the entire hindbrain spanning r2-r7 acquires an r1 "ground state" identity, and nV, nVII (and likely nIX) BMNs are eliminated and replaced by a small number of efferent neurons with r1 identity (Waskiewicz et al, 2002). In these pbx-less mutants, the caudal hindbrain is relatively unaffected, and a few nX motor neurons still differentiate.…”

Section: Pbx Genesmentioning

confidence: 99%

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Turning heads: Development of vertebrate branchiomotor neurons

Chandrasekhar

2003

Developmental Dynamics

164

204

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The cranial motor neurons innervate muscles that control eye, jaw, and facial movements of the vertebrate head and parasympathetic neurons that innervate certain glands and organs. These efferent neurons develop at characteristic locations in the brainstem, and their axons exit the neural tube in well-defined trajectories to innervate target tissues. This review is focused on a subset of cranial motor neurons called the branchiomotor neurons, which innervate muscles derived from the branchial (pharyngeal) arches. First, the organization of the branchiomotor pathways in zebrafish, chick, and mouse embryos will be compared, and the underlying axon guidance mechanisms will be addressed. Next, the molecular mechanisms that generate branchiomotor neurons and specify their identities will be discussed. Finally, the caudally directed or tangential migration of facial branchiomotor neurons will be examined. Given the advances in the characterization and analysis of vertebrate genomes, we can expect rapid progress in elucidating the cellular and molecular mechanisms underlying the development of these vital neuronal networks.

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Section: Pbx Genesmentioning

confidence: 99%

Section: Pbx Genesmentioning

confidence: 99%

Section: Pbx Genesmentioning

confidence: 99%

See 1 more Smart Citation

Turning heads: Development of vertebrate branchiomotor neurons

Chandrasekhar

2003

Developmental Dynamics

164

204

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“…In situ hybridizations were performed as described in Oxtoby and Jowett (1993) and Waskiewicz et al (2002). Cloning of zebrafish dpr1 and dpr2 and probes used were reported in Waxman et al (2004).…”

Section: In Situ Hybridizationsmentioning

confidence: 99%

Regulation of the early expression patterns of the zebrafish Dishevelled-interacting proteins Dapper1 and Dapper2

Waxman

2005

Dev. Dyn.

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The Dapper/Frodo family of proteins are Dishevelled-interacting regulators of Wnt signaling. In this study, I characterize the regulation of the early expression patterns of dpr1 and dpr2. Although both dpr1 and dpr2 are expressed on the prospective dorsal side, I find that their pregastrula expression patterns have differences that have not been reported previously. Early dpr1 expression is much more dynamic than dpr2 expression. I use gain and loss of function experiments to identify dorsal organizer genes that regulate dpr1 and dpr2 expression. The dorsalizing factors ␤-catenin, Bozozok (Boz), Noggin (Nog), and the mesendoderminducing factor Squint (Sqt) are all able to induce ectopic expression of dpr1 and dpr2. In reciprocal loss of function experiments, loss of maternal ␤-catenin signaling leads to loss of early dorsal dpr1 and dpr2 expression, whereas loss of Boz and/or Nodal signaling does not. Ectopic expression of the ventralizing molecule Bmp2b leads to reduction of dpr1 and dpr2 expression. These results suggest that, in early zebrafish development, dpr1 and dpr2 are targets of ␤-catenin and/or an unknown downstream effector.

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“…Anterior Hox genes play a prominent role in this process. Misregulation or disruption of Hox gene function leads to loss of specific segments or altered segment identity (Lufkin et al, 1991;Chisaka et al, 1992;Mark et al, 1993;Alexandre et al, 1996;Studer et al, 1996;Jungbluth et al, 1999;Bell et al, 1999;Rossel and Capecchi, 1999;McClintock et al, 2001;Waskiewicz et al, 2002). Retinoic acid (RA) secreted from posterior mesoderm regulates Hox gene expression in the hindbrain.…”

Section: Introductionmentioning

confidence: 99%

Rhombomere boundaries are Wnt signaling centers that regulate metameric patterning in the zebrafish hindbrain

Riley

Chiang

Storch

et al. 2004

Developmental Dynamics

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The vertebrate hindbrain develops from a series of segments (rhombomeres) distributed along the anteroposterior axis. We are studying the roles of Wnt and Delta-Notch signaling in maintaining rhombomere boundaries as organizing centers in the zebrafish hindbrain. Several wnt genes (wnt1, wnt3a, wnt8b, and wnt10b) show elevated expression at rhombomere boundaries, whereas several delta genes (dlA, dlB, and dlD) are expressed in transverse stripes flanking rhombomere boundaries. Partial disruption of Wnt signaling by knockdown of multiple wnt genes, or the Wnt mediator tcf3b, ablates boundaries and associated cell types. Expression of dlA is chaotic, and cell types associated with rhombomere centers are disorganized. Similar patterning defects are observed in segmentation mutants spiel-ohne-grenzen (spg) and valentino (val), which fail to form rhombomere boundaries due to faulty interactions between adjacent rhombomeres. Stripes of wnt expression are variably disrupted, with corresponding disturbances in metameric patterning. Mutations in dlA or mind bomb (mib) disrupt Delta-Notch signaling and cause a wide range of patterning defects in the hindbrain. Stripes of wnt1 are initially normal but subsequently dissipate, and metameric patterning becomes increasingly disorganized. Driving wnt1 expression using a heat-shock construct partially rescues metameric patterning in mib mutants. Thus, rhombomere boundaries act as Wnt signaling centers required for precise metameric patterning, and Delta signals from flanking cells provide feedback to maintain wnt expression at boundaries. Similar feedback mechanisms operate in the Drosophila wing disc and vertebrate limb bud, suggesting coaptation of a conserved signaling module that spatially organizes cells in complex organ systems.

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Eliminating Zebrafish Pbx Proteins Reveals a Hindbrain Ground State

Cited by 172 publications

References 43 publications

Turning heads: Development of vertebrate branchiomotor neurons

Turning heads: Development of vertebrate branchiomotor neurons

Regulation of the early expression patterns of the zebrafish Dishevelled-interacting proteins Dapper1 and Dapper2

Rhombomere boundaries are Wnt signaling centers that regulate metameric patterning in the zebrafish hindbrain

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