Transcriptional activation of vesicular monoamine transporter 2 in the pre-B cell line Ea3.123

Abstract

Uptake and storage of monoamines in secretory granules is accomplished by vesicular monoamine transporters, and it is likely that vesicular monoamine transporter 2 (VMAT2) is important for histamine transport in vivo. In the present study we have used the pre-B-cell line Ea3.123 to investigate the mechanisms involved in the transcriptional activation of the VMAT2 gene. In Ea3.123 cells, VMAT2 mRNA abundance was increased following mobilization of intracellular calcium, and this increased mRNA expression was paralleled by changes in l-histidine decarboxylase mRNA, suggesting that VMAT2 may be responsible for sequestration of histamine into secretory vesicles in this cell line. We cloned the 5'-flanking region of the VMAT2 gene and determined its transcriptional start site by primer extension of rat VMAT2 mRNA. There was no TATA or TATA-like sequence upstream of this region; instead there were GC-rich elements, Ca2+/cAMP-response-element- and SP1-binding motifs. Approx. 900 bp upstream of the transcriptional start site was a purine-pyrimidine repeat sequence that may form a Z-DNA structure. A series of 5'-deletional VMAT2-promoter segments cloned upstream of a luciferase reporter were capable of driving transcription and indicated the presence of multiple regulatory elements, while stimulation with ionomycin or PMA resulted in an increased level of the transcriptional activity of the 5'-promoter segments studied.

Vesicular Monoamine Transporter 2 (VMAT2) Expression in Hematopoietic Cells and in Patients with Systemic Mastocytosis

“…In contrast, absence of VMAT1 and VMAT2 from other cells of the hematopoietic and lymphoid lineage (e.g., eosinophil and neutrophil granulocytes, erythropoietic cells, lymphocytes and plasma cells) shows that vesicular monoamine storage mechanisms are restricted to megakaryocytes and basophil granulocytes. Though it has been suggested that VMATs can be transcriptionally activated in a preB-cell line and may be present in peripheral blood lymphocytes (Watson et al 1999; Amenta et al 2001), we could not confirm these observations in situ. Although there is strong evidence in the literature that lymphocytes synthesize catecholamines (Bergquist et al 1994; Josefsson et al 1996; Musso et al 1996), our results suggest that storage of monoamines in lymphocytes is not dependent on VMATs.…”

Chemical neuroanatomy of the vesicular amine transporters

“…As in the basophil, the dendritic cell function of VMAT2 remains unclear, as do the domains of the VMAT2 gene that determine its expression in the hematopoietic cell lineage. It is of interest that pre-B cells express the VMAT2 gene, which is up-regulated along with the histidine decarboxylase gene by increased intracellular calcium (62).…”

The VMAT2 gene in mice and humans: amphetamine responses, locomotion, cardiac arrhythmias, aging, and vulnerability to dopaminergic toxins

“…Data about the mouse gene can now be assembled with data from the human cDNAs and genes from Uhl and colleagues, Xu and colleagues (5–7), Hasama, Uhl et al (unpublished results); from the rat gene from Watson and co‐workers (8); and from genomic databases to provide the human VMAT2 gene structures noted in Fig. 1.…”

“…This 5′ flanking region is also rich in transcription factor recognition motifs. Approximately 2 kb portions of this region can drive reporter gene expression in rat lymphoid precursor cells that normally express VAMT2 (8). This promoter sequence fragment is also able to support expression of a sensitive reporter gene in SHSY‐5Y cells that normally express little VMAT2 (7).…”