Effect of Regulatory Element DNA Methylation on Tissue-Type Plasminogen Activator Gene Expression

Abstract

Expression of the tissue-type plasminogen activator gene (t-PA; gene name PLAT) is regulated, in part, by epigenetic mechanisms. We investigated the relationship between PLAT methylation and PLAT expression in five primary human cell types and six transformed cell lines. CpG methylation was analyzed in the proximal PLAT gene promoter and near the multihormone responsive enhancer (MHRE) -7.3 kilobase pairs upstream of the PLAT transcriptional start site (TSS, -7.3 kb). In Bowes melanoma cells, the PLAT promoter and the MHRE were fully unmethylated and t-PA secretion was extremely high. In other cell types the region from -647 to -366 was fully methylated, whereas an unmethylated stretch of DNA from -121 to +94 was required but not sufficient for detectable t-PA mRNA and t-PA secretion. DNA methylation near the MHRE was not correlated with t-PA secretion. Specific methylation of the PLAT promoter region -151 to +151, inserted into a firefly luciferase reporter gene, abolished reporter gene activity. The region -121 to + 94 contains two well-described regulatory elements, a PMA-responsive element (CRE) near -106 and a GC-rich region containing an Sp1 binding site near +59. Methylation of double-stranded DNA oligonucleotides containing the CRE or the GC-rich region had little or no effect on transcription factor binding. Methylated CpGs may attract co-repressor complexes that contain histone deacetylases (HDAC). However, reporter gene activity of methylated plasmids was not restored by the HDAC inhibitor trichostatin. In conclusion, efficient PLAT gene expression requires a short stretch of unmethylated CpG sites in the proximal promoter.

DNA Methylation of ProximalPLATPromoter in Chronic Rhinosinusitis With Nasal Polyps

“…The epigenetic mechanism regulating the PLAT gene expression has been studied in other tissues, [21][22][23] and several elements are associated with regulation of PLAT gene expression, and most of them are located in the proximal promoter legion. 24 Based on the methylation patterns, CpG sites of proximal promoter are classified into 2 legions: from position À647 to À366 and À121 to þ94 with respect to the transcription initiation site.…”

The Ameliorating Effects of Bee Pollen on Scopolamine-Induced Cognitive Impairment in Mice

“…Previously, it has been reported that tPA transcription level is modulated by cAMP-responsive element bindings to the promotor region of tPA gene (PLAT; gene name of tPA). [54][55][56] Therefore, our results suggest that bee pollen extract would increase tPA expression, probably, through ERK-CREB pathway, resulting in the enhancing conversion of proBDNF to mBDNF in the hippocampus. We also observed that the bee pollen extract enhanced cognitive function in normal naïve mice, as measured by the passive avoidance test.…”

“…29,30) BDNF processing is controlled by several converting enzymes such as pro-protein convertase 1, furin, and matrix metalloproteinase-9, as well as tPA. 52,53) Therefore, we measured the mRNA level of tPA in the hippocampal tissue, and the increased mRNA level of tPA was observed. Thus, it is likely that the increase of BDNF level in the hippocampus might be derived from the increase of conversion rate of proBDNF to mBDNF.…”

The Role of Epigenetics in the Regulation of Hemostatic Balance

“…This important evidence thus prompted the assessment of DNA methylation as new and potential contributing factor. To date, three molecules participating in blood coagulation or fibrinolysis were found to be more highly influenced by DNA methylation markers, that is, factor VII (FVII), 19 FVIII, 20,21 and tissuetype plasminogen activator (t-PA) [22][23][24] (►Fig. 1).…”

“…Such regulation might in turn have an impact on t-PA concentrations in both physiological and pathological conditions. 22…”