4.5 kb of the rat tyrosine hydroxylase 5 ' flanking sequence directs tissue specific expression during development and contains consensus sites for multiple transcription factors

To delineate DNA sequences responsible for developmentally correct expressi on of the rat tyrosine hydroxylase (TH) gene, we analyzed a line of transge nic mice expressing high levels of human placental alkaline phosphatase (AP ) under control of 4.5 kb of 5' flanking DNA from the rat TH gene in embryo s and adults. Several regions, such as the accessory olfactory bulb, which were not thought to synthesize TH protein or do so only transiently, were s hown to express TH protein using an improved method of antigen retrieval fo r TH immunohistochemistry. Many of these regions had been shown to express TH-driven reporter genes in transgenic mice. In the central nervous system, AP was detected in essentially all TH-expressing cell groups throughout de velopment and in adults. In the peripheral nervous system, transgene expres sion paralleled endogenous TH expression in the developing adrenal medulla and sympathetic ganglia but not in transiently TH-positive cells in dorsal root ganglia. Peripheral expression in the adult adrenal medulla was very w eak and absent in sympathetic ganglia. The specificity with which the 4.5 k b region directs transgene expression in embryos is comparable to that obse rved with longer 5' flanking promoter regions, implying that this region co ntains the control elements for appropriate expression during development. Sequence analysis of the region demonstrates a GT dinucleotide repeat, an e lement that resembles the neural restrictive silencer element (NRSE), which restricts transcription of neuronal genes in non-neuronal cells, and conse nsus sites for three families of transcription factors, Ptx1/3, Nurr1 and G li1/2, which are required for the early differentiation of mesencephalic ne urons. (C) 1999 Elsevier Science B.V. All rights reserved.