Disruption of Segmental Neural Crest Migration and Ephrin Expression in Delta-1 Null Mice

Abstract

Neural crest cells migrate segmentally through the rostral half of each trunk somite due to inhibitory influences of ephrins and other molecules present in the caudal-half of somites. To examine the potential role of Notch/Delta signaling in establishing the segmental distribution of ephrins, we examined neural crest migration and ephrin expression in Delta-1 mutant mice. Using Sox-10 as a marker, we noted that neural crest cells moved through both rostral and caudal halves of the somites in mutants, consistent with the finding that ephrinB2 levels are significantly reduced in the caudal-half somites. Later, mutant embryos had aberrantly fused and/or reduced dorsal root and sympathetic ganglia, with a marked diminution in peripheral glia. These results show that Delta-1 is essential for proper migration and differentiation of neural crest cells. Interestingly, absence of Delta-1 leads to diminution of both neurons and glia in peripheral ganglia, suggesting a general depletion of the ganglion precursor pool in mutant mice.

Cell-type-specific regulation of distinct sets of gene targets by Pax3 and Pax3/FKHR

“…Inspection of the region 5 0 of the EphA4 gene reveals at least one potential Pax3 PD binding site (Chalepakis et al, 1994b;Chalepakis and Gruss, 1995;Underhill et al, 1995;Underhill and Gros, 1997) at À83 (5 0 CACGTCACCGGC). Likewise, EFNB2, another factor involved in somite development (Durbin et al, 1998;Johnson et al, 2001;Barrios et al, 2003) and polarized trafficking of axons and neural crest cells through the somite (Wang and Anderson, 1997;Koblar et al, 2000;De Bellard et al, 2002), was induced by Pax3 and Pax3/FKHR in SaOS-2 cells. EFNB2 harbours two Pax3 DNA-binding consensus sequences upstream of the transcript start (À3 and À355).…”

Lunatic fringe causes expansion and increased neurogenesis of trunk neural tube and neural crest populations

“…More importantly, lunatic fringe-null mice have severe reduction in sensory ganglia size, which indicates fewer neurons (Evrard et al, 1998;Zhang and Gridley, 1998). During formation of the DRG in these mutant mice we noted that the initial rate of neurogenesis and gliogenesis was significantly impaired (de Bellard et al, 2002). Together with the present results we hypothesize that, in addition to modulating Notch/Delta signaling, lunatic fringe might play a role in the Notch/Delta interactions that are important for maintaining the pool of progenitors from which neurons and glia derive, thus accounting for the observed increase in neurogenesis.…”

Coordinated Action of N-CAM, N-cadherin, EphA4, and ephrinB2 Translates Genetic Prepatterns into Structure during Somitogenesis in Chick

“…Mesp2 further leads to transient expression of EphA4 in the anterior compartments (Nakajima et al, 2006), which peaks near the presumptive anterior boundary. In the posterior compartments, DLL maintains ephrinB2 expression (De Bellard et al, 2002), peaking near the presumptive boundary. Other protein level changes result from unknown mechanisms.…”