High impact information on pbx4

• Here, we report the identification and cloning of a zebrafish gene, lazarus, which is required globally for segmental patterning in the hindbrain and anterior trunk [1].
• Lastly, we observe a progressive anterior displacement of endoderm-derived organs upon disruption of meis3 or pbx4, apparently as a result of underdevelopment of the pharyngeal region [2].
• Furthermore, global over-expression of sema3Gb phenocopies the aberrant cranial NC phenotype of lzr/pbx4 mutants when endogenous Sema3 ligands are knocked down, consistent with a model in which the patterned expression of Sema3 ligands in the head periphery coordinates the migration of Nrp-expressing cranial NCCs [3].
• Using genetic mosaic analysis, we show that lzr/pbx4 and hoxb1a are primarily required cell-autonomously within the facial motor neurons; however, analysis of a subtle non-cell-autonomous effect indicates that facial motor neuron migration is promoted by interactions amongst the migrating neurons [4].
• We show that lazarus/pbx4, which encodes an essential Hox DNA-binding partner in zebrafish, is required for facial (VIIth cranial nerve) motor neuron migration and for axon pathfinding of trigeminal (Vth cranial nerve) motor axons [4].

Biological context of pbx4

• Mutation of lazarus/pbx4, encoding a hox gene partner, and mutation of valentino/kreisler, a hox gene regulator, produce anterior-posterior axis disruptions of pharyngeal cartilages [5].

Anatomical context of pbx4

• Consistent with this, lzr/pbx4 interacts genetically with hoxb1a to control facial motor neuron migration [4].
• Our data indicate that meis3 and pbx4 regulate shh expression in anterior endoderm, thereby influencing patterning and growth of the foregut [2].
• We present the characterization of a zebrafish pbx CDNA that appears to encode a novel family member, pbx4. pbx4 RNA is maternally deposited and is detected throughout the zebrafish embryo during blastula stages [6].

References