Overexpression of c‐Fos is sufficient to stimulate tyrosine hydroxylase (TH) gene transcription in rat pheochromocytoma 
PC18 cells

Abstract

The AP1 site within the tyrosine hydroxylase gene proximal promoter is essential for the response of the gene to numerous stimuli. Stimulation of this gene is often associated with induction of the AP1 transcription factor, c-Fos. However, many stimuli activate or induce multiple transcription factors that interact with this AP1 site or other sites within the gene's proximal promoter. Hence, it remains unclear whether c-Fos induction by itself is sufficient to stimulate the tyrosine hydroxylase gene. In this study we produce rat pheochromocytoma PC18 cells that overexpress c-Fos under control of the tet-inducible system. We demonstrate that induction of c-Fos leads to dramatic stimulation of tyrosine hydroxylase gene transcription rate measured using nuclear run-on assays. This stimulation is closely associated quantitatively with the induction of c-Fos and does not apparently require phosphorylation of c-Fos. The response is partially dependent on the AP1 site within the tyrosine hydroxylase proximal promoter. However, the response of the proximal promoter to c-Fos induction is relatively small compared with that of the endogenous gene. Consequently, our results suggest that c-Fos exerts its influence on the tyrosine hydroxylase gene via multiple mechanisms that are dependent and independent of the proximal promoter AP1 site.

Chronic Nicotine Treatment Leads to Induction of Tyrosine Hydroxylase in Locus Ceruleus Neurons: The Role of Transcriptional Activation

“…PC18 cells were cultured and treated as described in previous studies (Tank et al, 1986;Fossom et al, 1992;Sun and Tank, 2002). The cells were isolated after 1 h of treatment with either 0.1 mM 8-chlorophenylthio-cAMP (8-CPTcAMP) or 0.1 M dexamethasone.…”

“…The cells were isolated after 1 h of treatment with either 0.1 mM 8-chlorophenylthio-cAMP (8-CPTcAMP) or 0.1 M dexamethasone. Nuclear run-on assays were performed as described by Sun and Tank (2002).…”

Chronic Nicotine Treatment Leads to Sustained Stimulation of Tyrosine Hydroxylase Gene Transcription Rate in Rat Adrenal Medulla

“…Western analysis was used to measure levels of AP1 transcription factors essentially as described in previous publications (NagamotoCombs et al, 1997;Sun and Tank, 2002). Briefly, whole cell extracts (10 g of protein) were subjected to SDS-polyacrylamide gel electrophoresis and transferred to nitrocellulose membranes.…”

Molecular Mechanism of Regulation of MTA1 Expression by Granulocyte Colony-stimulating Factor

“…TH. At a molecular level, our proposed mechanism of G-CSF action in inducing MTA1 via c-Fos is supported by the findings that G-CSF triggers a de novo induction of c-Fos, and overexpression of c-Fos is sufficient to stimulate TH gene transcription (44,45). Furthermore, this induction of c-Fos by G-CSF was shown to be modulated by both MAPK and STAT3 signaling pathways (34,46).…”