Hoxb1

..We propose a model for the patterning of the branchial region, according to which the segmental identity in this area is provided mainly by the branchial arches...

..This variability suggests the presence of a compensating gene or genes, whose utilization is stochastic. A reasonable candidate for providing this compensatory function is the paralogous gene Hoxb-3...

..Point mutations in the RARE abolish expression in neuroectoderm. Therefore, this RARE is not only involved in the ectopic response to retinoic acid, but is also essential for establishing aspects of the early Hoxb-1 expression pattern...

..These data indicate that Celsr1-3 differentially regulate FBM neuron migration. Celsr1 helps to specify the direction of FBM neuron migration, whereas Celsr2 and 3 control its ability to migrate...

..of any combination of the Hox3 paralogous genes results in ectopic expression of the r4-specific determinant Hoxb1. This ectopic expression in turn results in the differentiation of r4-like facial branchiomotoneurons within this ..

..We report that timely induction of a Hoxb1 transgene in ESC-derived NSCs resulted in the specification of NSCs toward a hindbrain-specific identity through ..

..Here r3 axons turned in the opposite direction and exited as facial nerves from r4. These changes of neuroectodermal fates indicate a linkage between axonal pathfinding and intrinsic neuronal specification by Hox codes...

..In addition, these data suggest that the control of the development of r3 may not be autonomous but dependent on interactions with Hoxa1-expressing cells...

..These results demonstrate that, as a part of its role in maintaining rhombomere identity, Hoxb-1 is involved in controlling migratory properties of motor neurons in the hindbrain...

....

..patterning in the hindbrain, we analysed neurogenesis, neuronal differentiation and motoneuron migration in Hoxa1, Hoxb1 and Hoxb2 mutant mice...

....

In vertebrates, paralogous Hox genes play diverse biological roles. We examined the interchangeability of Hoxa1 and Hoxb1 in mouse development by swapping their protein-coding regions...

..Interestingly, although the RARE is not required for the spatiotemporal control of colinear expression of the Hoxa genes, it is absolutely required for correct Hoxa-2 expression in rhombomere 5...

..Moreover, the subsequent differentiation of central serotonergic neurons required both the suppression of VMN neurogenesis and the induction of downstream intrinsic determinants of serotonergic identity by Foxa2...

..We conclude that Krox-20, although not required for the initial delimitation of r3 and r5, plays an important role in the process of segmentation governing hindbrain development...

Hoxa1 and Hoxb1 have overlapping synergistic roles in patterning the hindbrain and cranial neural crest cells...

..HNF-3 beta is not required for the development of definitive endoderm cells, but foregut morphogenesis is severely affected in HNF-3 beta -/- embryos...

..Retinoids and their nuclear receptors may therefore participate in sharpening segment-restricted expression of Hoxb-1 during rhombomere boundary formation...

..Thus, the transforming growth factor-beta (TGF-beta) receptor ALK5, which until now has only been associated with the biological functions of TGF-beta1 to TGF-beta3 proteins, mediates GDF11 signalling during embryogenesis...

The Hoxb1 autoregulatory enhancer directs segmental expression in vertebrate hindbrain...

..This functional genomic approach allows the rapid identification of functionally important components of embryonic development from large datasets of putative targets...

..Thus, Fgf8 plays a critical upstream role in an FGF signaling cascade required for otic induction in chick and mouse...

..Our data suggest that, as in the posterior gut endoderm, exclusion of Shh expression from developing primordia is required for the proper development of pharyngeal-derived organs...

....

..1992; Nieto et al., 1992), these data indicate that members of the Eph family of RTKs may co-operate in the segmental patterning of the hindbrain...

..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 ..

..using the Cre/loxP system to drive the activation of different ROSA26 reporter alleles under the regulation of the hoxb1 locus...

..Finally, examination of embryos carrying three out of the four mutant Fgf alleles revealed intermediate phenotypes, suggesting a quantitative requirement for FGF signalling in otic vesicle formation...

..These results underscore the importance of maternal retinoids in preventing congenital birth defects, and lead to a revised model of the importance of RDH10 and RALDHs in controlling embryonic RA distribution...

....

....

....

..The ability of NC and placodal cells to, respectively, differentiate and migrate despite a positional mismatch along the A/P axis reflects the plasticity in the relationship between the two neurogenic precursors of the vertebrate head...

..We have previously shown that Retinoic Acid (RA) signal participates to this patterning. We now show that Hoxb1, Hoxa1, and Hoxa3, as downstream RA targets, are expressed in distinct sub-domains within the SHF...

..e. anteroposterior positional information is acquired by mesoderm, mesoderm induces positional values within (neuro-) ectoderm and endoderm, and both events occur within a restricted window of time...

..This may be a common pathogenic pathway when second heart field and septation defects are coupled...

..We used the Cre-loxP system and two Cre-driver lines (Egr2(Cre) and Hoxb1(Cre)) to delete Atoh1 from different regions of the cochlear nucleus (CN) and accessory auditory nuclei (AAN)...

..This suggests that an alternative tissue in the vicinity of the outflow tract of the heart responds directly to RA, and thereby induces or permits the neural crest cell lineage to initiate aorticopulmonary septation...

....

....

..Finally, our data suggest that the molecular cascade downstream of BMP signaling in early neural crest development may be different in mouse and avian embryos...

..Our results provide genetic evidence that expression of Apc at the normal level is essential for both anterior and ventral development, in the epiblast derivatives and visceral endoderm...

..Our results indicate that Fgfr1 patterns the pharyngeal region to create a permissive environment for neural crest cell migration...

..These data demonstrate that Krox20 plays an essential role during development of the hindbrain and associated cranial sensory ganglia in mice...

..We conclude that the mouse kreisler gene regulates multiple steps in segmental patterning involving both the formation of segments and their A-P identity...

....

..We show that such mutant embryos lack foregut and midgut endoderm. In addition, left-right asymmetry is affected in the mutant embryos...

....

..Altogether, these results demonstrate that Otx2 is first required in the visceral endoderm for the induction, and subsequently in the neuroectoderm for the specification of forebrain and midbrain territories...

..These results indicate that the rae28 gene is involved in the regulation of Hox gene expression and segment specification during paraxial mesoderm and neural crest development...

....

..We hypothesize the early expression of insulin in the YS is required for the expansion of insulin responsive cells including primitive erythroblasts...

....

..Instead of forming a defined r4, Hoxb1- and Wnt8A-expressing cells are scattered throughout the caudal hindbrain, whereas r5/r8 markers such as kreisler ..

..This navigational error could explain the disappearance, at around 17.5 dpc, of the trigeminal motor nucleus in Krox-20(-/-) embryos by inadequate supply of essential, possibly arch-specific survival factors...

..These results suggest a molecular link between Hox gene activation and the segmentation clock. Such a linkage would efficiently keep in phase the production of novel segments with their morphological specification...

..The amount of Hoxb-4, -b-2, and -c-4 message in skin is relatively constant from the earliest gestational day examined (day 16) through birth at day 19. Expression of several homeobox genes is also seen in adult skin...

....

..Previously, two RAREs located 3' of the murine Hoxb1 gene, a DR(2) RARE and a DR(5) RARE, have been shown to regulate Hoxb1 mRNA expression in the neural epithelium ..

..The identity, expression, and mutant phenotype of kr indicate an early role in axial patterning and provide insights into the molecular and embryologic mechanisms that govern hindbrain and otic development...

..The first changes in chromatin structure and nuclear organisation were detected during gastrulation in the Hoxb1-expressing posterior primitive streak region: Hoxb chromatin was decondensed and the Hoxb1 locus looped out from ..

The analysis of Hoxa1 and Hoxb1 null mutants suggested that these genes are involved in distinct aspects of hindbrain segmentation and specification. Here we investigate the possible functional synergy of the two genes...

..We determined that the kr chromosomal inversion caused ectopic Kreisler expression in r3 of kr/kr and kr/+ embryos. Hence, Kreisler regulates maintenance and expansion of r5 and specification of r6 but is not required for r3 development...

..These findings indicate that, instead of the addition of inductive signals, minimization of exogenous patterning signaling plays a key role in rostral hypothalamic specification of neural progenitors derived from pluripotent cells...

..Thus, it is likely that decreased cell death in the ventral forebrain of caspase-3- and caspase-9-deficient 129/Sv mice increases the number of neuroprogenitor cells in the MGE, leading to hyperplasia of the forebrain...

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...

..Loss of Pbx3 function thus leads to the incorrect specification of some glutamatergic neurons in the dorsal horn and alters the integration of peripheral sensation into the spinal circuitry regulating locomotion...

..prior to initial expression of the first Hox gene, a dramatic transcriptional stimulation of the 3'most genes, Hoxb1 and Hoxb2, is observed upon a short pulse of exogenous retinoic acid (RA), whereas it is not in the case for more ..

..Thus, we suggest that del22q11 is a contiguous gene syndrome involving dose-sensitive interaction of CRKL and TBX1 and locally aberrant RA signaling...

....

..Thus Blimp1 probably acts to turn off the default pathway that allows epiblast cells to adopt a somatic cell fate, and shifts the transcriptional program so that they become exclusively allocated into the germ cell lineage...

..Given the diversity, localisation and nature of the defects, we propose that some of them are caused by the elimination of the IrxB cluster, while others result from the loss of one or several of the Fts, Ftm and Fto genes...

....

..Using linkage analysis we have localized the Hfh2 gene to chromosome 4 at 44.91 cM from the centromere...

..Our results suggest that rae28 is not required for the establishment but maintenance of Hoxb3 expression...

..We provide genetic evidence that ALDH1A2 and CYP26A1 activities concurrently establish local embryonic retinoic acid levels that must be finely tuned to allow posterior organ development and to prevent spina bifida...

..They also give insight into the formation of pharyngeal pouches, of which little is known in vertebrates. Finally, this work introduces two new players in craniofacial development - SOX3 and SOX2...

..abstract_text> ..

..Therefore, our proposed studies should shed light on abnormal regulation of Fgf8 splicing on pathological conditions, including tumor formation in human. ..

..Therefore, our proposed studies should shed light on abnormal regulation of Fgf8 splicing on pathological conditions, including tumor formation in human. ..

..It is hoped that this information will provide insight into a number of human diseases that affect touch sensation. ..