Reelin down-regulation in mice and psychosis endophenotypes.
Reelin, a large glycoprotein secreted by telencephalic GABAergic neurons, plays an important role in neuronal guidance embryonically and in synaptic plasticity postnatally. The reeler heterozygous mouse (+/rl) appears superficially normal but has been of interest as an animal model for psychosis since the discovery that reelin is 50% down-regulated in postmortem psychotic brain. Brain abnormalities in +/rl are similar to psychotic brain and include a reduction in glutamic acid de carboxylase 67 (GAD67), dendritic arbors and spine density in cortex and hippocampus, and abnormalities in synaptic function including long-term potentiation (LTP). In spite of these abnormalities, behavioral abnormalities in +/rl are subtle and controversial. Recent findings indicate that the reelin (RELN) and GAD67 promoters are hypermethylated in GABAergic neurons of psychotic postmortem brain and that DNA methyltransferase 1 (DNMT1) is up-regulated. Hypermethlyation of RELN and GAD67 promoters can be induced by treating mice with methionine, and these mice display brain and behavioral abnormalities similar to +/rl. Thus, an animal model that combines genetic heterozygocity with epigenesis holds promise for understanding the role of Reelin down-regulation in psychosis.
T10 T11 T12 T1 T2 T3 T4 T5 T6 T7 T8 T9
GENE-Y GENE-N GENE-Y CHEMICAL CHEMICAL GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N GENE-Y
DNMT1 RELN and GAD67 promoters Reelin methionine glutamic acid Reelin Reelin reelin glutamic acid de carboxylase 67 GAD67 reelin (RELN) and GAD67 promoters DNA methyltransferase 1