... Hindbrain Motor neurons Dorsoventral Shh Hoxb1 Chick Retinoic acid (RA), the biologically active derivative of vitamin A(retinol), is well established as a potent regulator of many aspects of early embryo development. Both gain- and loss-of-function studies have provided direct evidence...

...Ioan Ovidiu Sirbu; Lionel Gresh; Jacqueline Barra; Gregg Duester Retinoic acid (RA) generated by Raldh2 in paraxial mesoderm is required for specification of the posterior hindbrain, including restriction of Hoxb1 expression to presumptive rhombomere 4 (r4). Hoxb1 expression requires 3′ and 5′ RA...

... that specify distinct neuronal types within the vertebrate neural tube. We have previously shown that in ventral rhombomere (r)4 of Hoxb1 and Hoxb2 mutant mouse embryos, Phox2b expression is not properly maintained in the visceral motoneuron progenitor domain (pMNv), resulting in a switch to serotonergic fate...

... earlier than overt Hox expression. The ability to express autonomously the earliest Hox gene, Hoxb1 , is present in the posterior streak region at the onset of gastrulation, but not in the anterior region at this stage. However, the posterior region can induce Hoxb1 expression in these anterior region...

... and targeted disruption of the homeobox gene Hoxb1 demonstrate that it is essential for patterning progenitor cells along the entire DV axis of rhombomere 4 (r4). Hoxb1 accomplishes this function by acting very early during hindbrain neurogenesis to specify effectors of the sonic hedgehog and Mash1 signaling...

... patterning defects were analyzed in embryos individually mutant for Hoxa1 and Hoxa2 in greater detail and extended to embryos mutant for both genes. From these data a model is proposed to describe how Hoxa1, Hoxa2, Hoxb1, Krox20 ( Egr2 ) and kreisler function together to pattern the early mouse hindbrain...

... on functional GATA2, which in turn is under the control of Hoxb1 . In particular, the absence of Hoxb1 results in the loss of GATA2 expression in r4 and the absence of GATA2 results in the loss of GATA3 expression. The lack of GATA3 expression in r4 inhibits the projection of contralateral vestibuloacoustic...

...Mireille Rossel; Mario R. Capecchi The analysis of mice mutant for both Hoxa1 and Hoxb1 suggests that these two genes function together to pattern the hindbrain. Separately, mutations in Hoxa1 and Hoxb1 have profoundly different effects on hindbrain development. Hoxa1 mutations disrupt...