IDENTIFICATION BY DIFFERENTIAL RT-PCR OF A NOVEL PAIRED HOMEODOMAIN PROTEIN SPECIFICALLY EXPRESSED IN SENSORY NEURONS AND A SUBSET OF THEIRCNS TARGETS

Sensory neurons are a major derivative of the neural crest for which t here have been no definitive molecular markers in mammals. We have dev eloped a method that combines differential hybridization with degenera te RT-PCR to rapidly screen gene families for members exhibiting diffe rential expression among tissues or cell types. We used this approach to search for transcription factor-encoding genes specifically express ed in mammalian sensory neurons. A novel paired homeodomain protein, c alled DRG11, was identified. DRG11 is expressed in most sensory neuron s, including trkA-expressing neurons, but not in glia or sympathetic n eurons. Unexpectedly, it is also expressed in the dorsal horn of the s pinal cord, a region to which NGF-dependent sensory neurons project. T hese data suggest that DRG11 is not only a useful marker for sensory n eurons, but may also function in the establishment or maintenance of c onnectivity between some of these neurons and their central nervous sy stem targets.