Species and Regional Differences in the Expression of Cell‐Type Specific Elements at the Human and Rat Tyrosine Hydroxylase Gene Loci

Abstract

The expression of the catecholamine biosynthetic enzyme, tyrosine hydroxylase (TH), is confined to several different types of neuroendocrine cells. Using a transient assay system, we examined more than 10 kb of the human TH gene and 6.5 kb of 5' flanking sequences of the rat TH gene for DNA elements that confer cell-type specific expression. Surprisingly, these elements do not appear to be conserved in position or sequence across species. When plasmids containing DNA sequences - 749 bp from the transcription start site of the rat gene were introduced into PC12 cells, up to sixfold higher levels of expression were observed as compared to the same fragments introduced into HepG2 cells or LAN-1 cells. In contrast to the rat gene, analogous fragments of the human 5' promoter failed to confer cell-type specific expression. However, when plasmids containing a truncated thymidine kinase promoter and either orientation of a 760 by 3' human TH gene fragment were introduced into PC12 and LAN-1 cells, we observed a six- and 3.5-fold increase, respectively, over that observed for HepG2 cells. Subsequent deletion of this fragment led to significant activation of transcription in PC12 and HepG2 cell lines. These data indicate the presence of multiple elements contributing to the cell-type specific expression of tyrosine hydroxylase genes.

The Cyclic AMP Response Element Directs Tyrosine Hydroxylase Expression in Catecholaminergic Central and Peripheral Nervous System Cell Lines from Transgenic Mice

“…A region between Ϫ503 and Ϫ578 bp has also been shown to direct rat TH expression in another PC12 line (Gandelman et al, 1990;Wong et al, 1994). Deletions that lacked the Ϫ503/ Ϫ578 bp region but retained the CRE reduced expression by 66%.…”

Orphan nuclear receptor Nurr1 directly transactivates the promoter activity of the tyrosine hydroxylase gene in a cell‐specific manner

“…Transcriptional regulation of the TH gene has been extensively investigated in numerous laboratories. In vivo transgenic mice experiments have been performed to address whether different promoter regions of the human, rat, and mouse TH gene can confer cell type-specific gene expression (Gandelman et al 1990;Kaneda et al 1991;Banerjee et al 1992;Min et al 1994;Wong et al 1995;Morgan et al 1996). Despite some variations between such studies, in general they established that 5¢ upstream sequences (> 5 kb) of the TH gene are able to drive reporter gene expression in most catecholaminergic (CA) neurons and endocrine cells, with some ectopic expressions.…”

Transcription and epigenetic profile of the promoter, first exon and first intron of the human tyrosine hydroxylase gene

“…Some studies shed useful insights in clarifying a confusing issue related to the comparison of TH gene regulation among various species, which is achieved through different mechanisms (Lenartowski and Goc, 2002;Lenartowski et al, 2003;Romano et al, 2005;Jin et al, 2006;Kelly et al, 2006). In this respect, a first important observation derived from the comparative analysis between the sequence of the human, mouse and rat TH promoters (Kessler et al, 2003;Romano et al, 2005), which revealed that the human TH promoter shares an approximate 46.6% degree of homology with the mouse TH promoter (Romano et al, 2005) and a 30% degree of homology with the rat TH promoter (Gandelman et al, 1990;Kim et al, 2003b). Only five short regions are evolutionarily conserved among the human, mouse and rat TH promoters (Kessler et al, 2003).…”

“…These studies focused mainly on the human (Kessler et al, 2003;Romano et al, 2005;Jin et al, 2006), mouse (Kim et al, 2003a) and rat models (Gandelman et al, 1990 et al, 2003b). In a previous report, a 13 kb DNA fragment containing the human TH promoter was isolated from a genomic DNA library, sequenced and utilized to generate both a transgenic animal model (Kessler et al, 2003) and a variety of recombinant minimal TH promoters assembled in a self-inactivating lentiviral vector system (Romano et al, 2005).…”

“…The degree of homology between the human and mouse TH promoters is about 46.6% (determined with a Clustalx program; Romano et al, 2005), whereas the human and rat TH promoters share only a 30% degree of homology (Gandelman et al, 1990;Kim et al, 2003b). The five CRs were placed upstream of the first-194 bp from the transcription start of the human TH promoter and the first 35 bp of the untranslated messenger RNA leader of the human TH gene (Romano et al, 2005).…”