Cadherin expression coincides with birth dating patterns in patchy compartments of the developing chicken telencephalon

Abstract

Some gray matter regions of the vertebrate brain, e.g., the mammalian striatum, are organized into clusters of functionally similar neurons ("patches") that are surrounded by a gray matter matrix. A similar type of compartmentation recently has been found also in the avian telencephalon, based on two sorts of evidence. First, a birth dating study showed that, in some telencephalic areas, cells born at the same time form "isochronic" cell clusters, which differ in their birth dating pattern from their surrounding tissue. Second, patchy expression was found for different members of the cadherin family of adhesion molecules (R-cadherin, N-cadherin, and/or cadherin-7). The relation between these two findings has remained unclear. Here, we demonstrate a general spatial coincidence between the birth dating patterns and the heterogeneities in cadherin expression. This coincidence is found in areas of the avian ventral and lateral pallium (ventral hyperstriatum, neostriatum, and ectostriatum) and in a part of the archistriatum, which is of pallial origin. For example, in the neostriatum, a part of the ventral pallium, both the cadherin-7-positive patches and their R-cadherin-positive surroundings are born between embryonic day 5 and 7, but the cadherin-7-positive cells are born during a shorter time period than the R-cadherin-positive cells. We propose that the patchy gray matter architecture observed in the mammalian striatum and avian pallium are regulated by a common type of morphogenetic mechanism. This mechanism possibly involves the differential expression of adhesive factors, such as cadherins.

BrdU Birth Dating Can Produce Errors in Cell Fate Specification in Chick Brain Development

“…Neurogenesis in the chick dorsal telencephalon occurs between E4 and E9 (Tsai et al 1981a(Tsai et al , 1981b, and isochronic cluster formation has been observed with BrdU delivery during peak neurogenesis (E5-E7) (Heyers et al 2003). By injecting E5 to E9 brains with the routine BrdU dose and collecting brains at E14 for BrdU detection and in situ hybridization, we established that BrdU clusters can be produced from E5 to E8 and are consistently associated with inappropriate EMX1 and DACH2 expression (Fig.…”

“…On E5 to E9, a small window was cut in the eggshell and 1 to 3 µl BrdU solution was injected into one of the embryo's vitelline veins through a glass micropipette (tip diameters: 20-40 microns) connected to a picospritzer. The 15-mg/ml dose is a "routine" dose similar to that employed in other studies of chick forebrain development (Striedter and Keefer 2000;Redies et al 2002;Heyers et al 2003). In scout experiments, we found that with the 0.15-mg/ml dose, BrdU was not detected over background (n=8 where all failed detection), whereas with the 0.5-mg/ml dose, a BrdU signal could be regularly, but not invariably, detected (n=18 where 2 failed detection) and is referred to in this study as the threshold dose.…”

Selective early expression of the orphan nuclear receptor Nr4a2 identifies the claustrum homolog in the avian mesopallium: Impact on sauropsidian/mammalian pallium comparisons

“…While this situation persists roughly across stages HH32-36, the MD and MV moieties of the adult mesopallium are not mutually distinguishable. However, the two sorts of postmitotic cells gradually segregate one from the other after stage HH36, possibly because of differential expression of cadherins known to mediate selective homologous adhesivity and consequent aggregative readjustments of cell positions (see Redies et al, 2001Redies et al, , 2002Heyers et al, 2003).…”

Regulated ADAM10-dependent Ectodomain Shedding of γ-Protocadherin C3 Modulates Cell-Cell Adhesion

“…The Pcdhs derived from these gene clusters are predominantly expressed in the nervous system and localized to synaptic junctions (4 -6). Functionally connected neurons are often characterized by the expression of a distinct set of cadherins, which may thus provide an adhesive code regulating neuronal differentiation and synaptogenesis (7)(8)(9). The family-specific constant domains of Pcdh␣-and Pcdh␥-proteins could transduce different extracellular informations into a common intracellular signaling pathway or other executive functions.…”