Dynamics of tyrosine hydroxylase promoter activity during midbrain dopaminergic neuron development

Abstract

Dopamine (DA)-producing neurons in the ventral midbrain are generated from a specified neuronal lineage and form selective axonal pathways that mediate multiple CNS functions. Expression of the gene encoding tyrosine hydroxylase (TH), which is a key enzyme of catecholamine biosynthesis, is regulated during the development of midbrain DA neurons. In the present study, we report the developmental regulation and cell type specificity of TH gene promoter in the ventral midbrain by using a green fluorescent protein (GFP) reporter system. Transgenic mice were generated that express GFP in the majority of midbrain DA neurons under the control of the 9-kb upstream region of the rat TH gene. At an early embryonic stage, GFP expression was induced in the developing DA neurons, and the expression was then markedly down-regulated at later embryonic stages. However, the expression was reactivated and approached the adult levels during early postnatal development. These developmental changes in GFP expression patterns suggest the presence of multistep regulatory mechanisms for TH gene expression during DA neuron development. The TH promoter appears to possess transcriptional elements at least necessary for the induction of TH expression at the early embryonic stage and its reactivation during the post-natal development.

Developmental and Target-Dependent Regulation of Vesicular Glutamate Transporter Expression by Dopamine Neurons

“…1 B). In line with a previous report (Matsushita et al, 2002), we detected a modest relative increase of TH mRNA level as a function of age (Fig. 1C).…”

“…Unless otherwise stated, experiments were performed using the tyrosine hydroxylase green fluorescent protein (TH-GFP) transgenic mouse line TH-EGFP/21-31, which carries the enhanced GFP (EGFP) gene under the control of the TH promoter (Sawamoto et al, 2001;Matsushita et al, 2002). In these mice, the vast majority of GFPexpressing cells are catecholaminergic neurons, although ectopic expression of GFP is also found in a minority of neurons, mostly at younger ages [younger than postnatal day 15 (P15)], possibly because of the fact that some elements are missing from the TH promoter used (Sawamoto et al, 2001;Matsushita et al, 2002). As a control, we used wild-type mice of the same genetic C57BL/6 background (Charles River).…”

Glycine Transporter-1 Inhibition Promotes Striatal Axon Sprouting via NMDA Receptors in Dopamine Neurons

“…Coronal midbrain slices were prepared from TH-eGFP mice (Matsushita et al, 2002) using a vibratome (Leica VT1200) and superfused with artificial CSF (ACSF) containing the following (in mM): 119 NaCl, 26.2 NaHCO 3 , 10 glucose, 1.8 KCl, 1.2 MgCl 2 -6H 2 O, 1.0 NaH 2 PO 4 -6H 2 O, and 2.4 CaCl 2 . The recording chamber temperature was maintained at 32°C.…”

The migratory behavior of immature enteric neurons

“…The generation of the TH-GFP transgenic mice has been described previously (Sawamoto et al, 2001;Matsushita et al, 2002). The 9kb 5 0 upstream region of the rat TH gene was combined with a GFP coding variant, and the transgene injected into fertilized mouse eggs to produce a TH-GFP transgenic line.…”

“…These cells represent approximately 15% of neural crest-derived cells in the gut of E10.5 mice . In the current study, transgenic mice in which GFP is expressed under the control of the TH promoter (Sawamoto et al, 2001;Matsushita et al, 2002) were used to image immature enteric neurons in live tissue. In TH-GFP mice, GFP expression coincides with TH immunoreactivity in the midbrain (Sawamoto et al, 2001); however, GFP expression in the gut of embryonic TH-GFP mice has not previously been characterized.…”