Disruption of hippocampal development in vivo by CR-50 mAb against Reelin

Abstract

We previously generated a monoclonal alloantibody, CR-50, by immunizing reeler mutant mice with homogenates of normal embryonic brains. This antibody recently was shown to recognize a Reelin protein, which is coded by the recently identified candidate gene for the reeler mutation. However, it is still unclear whether Reelin, especially the CR-50 epitope region, is indeed responsible for the reeler phenotype in vivo. Here we show that Reelin is localized on Cajal-Retzius neurons in the hippocampus and that intraventricular injection of CR-50 at the embryonic stage disrupts the organized development of the hippocampus in vivo, converting it to a reeler pattern. Labeling experiments with 5-bromodeoxyuridine demonstrated that the labeled cells in the stratum pyramidale of the CR-50-treated mice were distributed in a pattern similar to that of reeler. Thus, Cajal-Retzius neurons play a crucial function in hippocampus development, and the CR-50 epitope on Reelin plays a central role in this function.

Mutant mice with scrambled brains: understanding the signaling pathways that control cell positioning in the CNS

“…After binding to lipoprotein receptors on the cell surface, Reln is internalized into vesicles. Binding of Reln to the receptors is inhibited by mAb CR-50, which blocks Reln function in vivo and in vitro (D'Arcangelo et al 1995(D'Arcangelo et al , 1999Ogawa et al 1995;Del Rio et al 1997;Nakajima et al 1997). These findings imply that Reln is a physiological ligand for lipoprotein receptors in the brain.…”

“…1). This abnormality can be recapitulated in rotating cultures of reeler neurons or by incubating normal neurons with the CR-50 antibody, which inhibits Reln function (Ogawa et al 1995;Nakajima et al 1997). The mechanism responsible for this phenotype is not clear.…”

Reelin signaling antagonizes β-amyloid at the synapse

“…It also increases their gating (25). NR2 phosphorylation by Reelin is greatly reduced in the presence of a high concentration of 1 M A␤ [25][26][27][28][29][30][31][32][33][34][35] (Fig. 2 A, lane 4).…”

“…1B, closed circles). This suppression was again fully reversible by co-application of Reelin (closed triangles), indicating that LTP suppression induced by low concentrations of A␤ 1-42 or A␤ [25][26][27][28][29][30][31][32][33][34][35] was not caused by a non-specific cytotoxic effect.We have reported earlier (20) that Reelin increases tyrosine phosphorylation of NR2A as well as NR2B subunits (Fig. 2A, lane 2, Upper and Lower, respectively).…”

“…Consistent with the findings in other laboratories, monomeric A␤ 1-42 (1°) was ineffective. A truncated form of the A␤ peptide consisting only of amino acids 25 to 35 (A␤ [25][26][27][28][29][30][31][32][33][34][35] ), which form the minimal fibrillogenic region was also able to potently suppress baseline LTP at consistently lower concentrations (100 nM; Fig. 1B, closed circles).…”