A HOMEODOMAIN GENE PTX3 HAS HIGHLY RESTRICTED BRAIN EXPRESSION IN MESENCEPHALIC DOPAMINERGIC-NEURONS

The mesencephalic dopaminergic (mesDA) system regulates behavior and m ovement control and has been implicated in psychiatric and affective d isorders, We have identified a bicoid-related homeobox gene, Ptx3, a m ember of the Ptx-subfamily, that is uniquely expressed in these neuron s, Its expression starting at E11.5 in the developing mouse midbrain c orrelates with the appearance of mesDA neurons, The number of Ptx3-exp ressing neurons is reduced in Parkinson patients, and these neurons ar e absent from 6-hydroxy-dopamine-lesioned rats, an animal model for th is disease, Thus, Ptx3 is a unique transcription factor marking the me sDA neurons at the exclusion of other dopaminergic neurons, and it may be involved in developmental determination of this neuronal lineage.