Selective Adhesion of Cells from Different Telencephalic Regions

Abstract

We asked whether specifications of different regions of the rodent and avian telencephalon during development involved the acquisition of differential adhesive properties. Cells from different regions were aggregated in a short-term aggregation assay, and their segregation was analyzed. Both neurons and precursor cells from cortex segregate from striatal cells at early, but not later, stages, whereas cells from rodent neocortex and hippocampus segregated only during later stages. Segregation was abolished when Ca2+-dependent but not Ca2+-independent adhesion molecules were selectively removed. Thus, selective adhesion appears to be a conserved mechanism that restricts cellular mixing and might serve to maintain positional information during forebrain development. A candidate for mediating the Ca2+-dependent segregation is the CD15 (Lewis(x)) carbohydrate epitope, which is selectively expressed by mammalian cortex but not striatum.

Bidirectional EphrinB3/EphA4 Signaling Mediates the Segregation of Medial Ganglionic Eminence- and Preoptic Area-Derived Interneurons in the Deep and Superficial Migratory Stream

“…To investigate the role of bidirectional ephrinB3-EphA4 signaling in the segregation of interneurons deriving from the two migratory routes after cell-cell contact, we performed a shortterm aggregation assay modified according to Gotz et al (1996). The initial aggregation of dissociated cells in this assay was described to reflect the expression and function of cell surface signaling molecules, restricting cellular mixing to maintain positional information during forebrain development (Gotz et al, 1996).…”

“…The aggregation assay was modified after Gotz et al (1996). In brief, dissociated cells of the VZ/SVZ and IMZ of the MGE of EGFP-expressing embryos and wild-type littermates were prepared as described above and collected in GBSS, which was then substituted by Ca 2ϩ /Mg 2ϩ -free HBSS with 1 mM EDTA (dissociation buffer).…”

“…Cellular clusters consisting of 10 or more cells were defined as an aggregate. According to Gotz et al (1996), we considered aggregates as "pure," when only one to two cells were from different domains. When cells of distinct domains were arranged in separate clusters within the same aggregate, they were classified as "clustered," while intermingled cells were defined as "mixed" aggregates.…”

Pax6 Controls the Expression of Lewis x Epitope in the Embryonic Forebrain by Regulating α1,3-Fucosyltransferase IX Expression

“…Pax6 mutant fails to establish the boundary between the cortical and striatal regions (6, 8, 14 -18). It has been proposed that Ca 2ϩ -dependent selective adhesion of the cortical cells segregating from the striatal cells contributes to the formation and maintenance of boundaries between these telencephalic regions (19). In Pax6 mutant, this selective adhesion of cortical cells is lost (16) and neural cell migration from the striatum into the cortex is strongly enhanced (20).…”

“…It has been reported that the cortex of the rat telencephalon at embryonic days 12 to 15 (E12-15) 1 distinctively expresses Lewis x epitope (19,21,22). The Lewis x epitope, which is also known as CD15 and SSEA-1 (stage-specific embryonic antigen-1), has been identified as a glycan epitope with a Gal␤1-4(Fuc␣1-3)GlcNAc␤1-structure (23)(24)(25).…”