title: On the epigenetic regulation of the human reelin promoter.
abstract: Reln mRNA and protein levels are reduced by approximately 50% in various cortical structures of post-mortem brain from patients diagnosed with schizophrenia or bipolar illness with psychosis. To study mechanisms responsible for this down-regulation, we have analyzed the promoter of the human reelin gene. We show that the reelin promoter directs expression of a reporter construct in multiple human cell types: neuroblastoma cells (SHSY5Y), neuronal precursor cells (NT2), differentiated neurons (hNT) and hepatoma cells (HepG2). Deletion constructs confirmed the presence of multiple elements regulating Reln expression, although the promoter activity is promiscuous, i.e. activity did not correlate with expression of the endogenous gene as reflected in terms of reelin mRNA levels. Co-transfection of the -514 bp human reelin promoter with either Sp1 or Tbr1 demonstrated that these transcription factors activate reporter expression by 6- and 8.5-fold, respectively. Within 400 bp of the RNA start site there are 100 potential CpG targets for DNA methylation. Retinoic acid (RA)-induced differentiation of NT2 cells to hNT neurons was accompanied by increased reelin expression and by the appearance of three DNase I hypersensitive sites 5' to the RNA start site. RA-induced differentiation was also associated with demethylation of the reelin promoter. To test if methylation silenced reelin expression, we methylated the promoter in vitro prior to transfection. In addition, we treated NT2 cells with the methylation inhibitor aza-2'-deoxycytidine and observed a 60-fold increase in reelin mRNA levels. The histone deacetylase inhibitors trichostatin A (TSA) and valproic acid also induced expression of the endogenous reelin promoter, although TSA was considerably more potent. These findings indicate that one determinant responsible for regulating reelin expression is the methylation status of the promoter. Our data also raise the interesting possibility that the down-regulation of reelin expression documented in psychiatric patients might be the consequence of inappropriate promoter hypermethylation.
authors.affiliation: Psychiatric Institute, Department of Psychiatry, 1601 West Taylor Street, M/C 912, College of Medicine, University of Illinois, Chicago, IL 60612, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Rajiv P
authors.initials: RP
authors.lastname: Sharma
authors.forename: Robert H
authors.initials: RH
authors.lastname: Costa
authors.forename: Erminio
authors.initials: E
authors.lastname: Costa
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Grayson
mesh_terms: D001483:Base Sequence; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics*; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002843:Chromatin / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects; D003845:Deoxycytosine Nucleotides / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D000091042:Reelin Protein; D012697:Serine Endopeptidases; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014635:Valproic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D002843:Chromatin; D003845:Deoxycytosine Nucleotides; D016326:Extracellular Matrix Proteins; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D000091042:Reelin Protein; C012589:trichostatin A; D014212:Tretinoin; D014635:Valproic Acid; D008156:Luciferases; C000717127:RELN protein, human; D012697:Serine Endopeptidases; D006655:Histone Deacetylases; C004651:dipropylacetamide