THE EXPRESSION PATTERN OF THE TRANSCRIPTION FACTOR PHOX2 DELINEATES SYNAPTIC PATHWAYS OF THE AUTONOMIC NERVOUS-SYSTEM

Many transcription factors, and most prominently among them, homeodoma in proteins, are expressed in specific groups of cells in the developi ng nervous system in patterns that suggest their involvement in neural fate determination. How various aspects of neural identity are contro lled by such transcription factors, or sets of them, is stili mostly u nknown. It has been shown previously that Phox2 is such a homeodomain protein, expressed exclusively in differentiated groups of neurons or their precursors, and that its expression correlated with that of the noradrenaline synthesis enzyme dopamine-beta-hydroxylase. Here we conf irm this striking correlation at the single-cell level with the use of an anti-Phox2 antibody. Moreover, we uncover a second, nonmutually ex clusive correlative clue to the Phox2 expression pattern: a high propo rtion of Phox2-expressing cells are involved in, or located in areas i nvolved in, synaptic circuits, i.e., that of the medullary control ref lexes of autonomic functions. This suggests that Phox2 could be involv ed in the establishment of these circuits.