Specific interaction of heterogeneous nuclear ribonucleoprotein A1 with the -219T allelic form modulates APOE promoter activity.
The polymorphic -219T/G variant in the APOE promoter has been associated with variations in basal transcriptional activity as well as with the risk of developing Alzheimer's disease, myocardial infarction and early-onset coronary heart disease. The molecular mechanisms underlying these effects are presently unknown. In this report, we show that nuclear extracts from Jurkat cells form a T-specific complex with a motif including the -219 site within the APOE promoter. By DNA-affinity chromatography and mass spectrometry, the human heterogeneous nuclear ribonucleoprotein hnRNPA1(A1) was identified as one component of the complex. In vitro binding analysis indicated that a fragment of A1 had a marked binding specificity for the T form. Interaction of A1 with this region is driven by an adjacent telomeric-like sequence; however, the presence of G, but not T, at -219 position inhibited this interaction. The differences in transcriptional activity between the -219T and -219G promoter allelic forms correlated with the expression levels of A1 in several cell lines; also, over-expression of A1 increased the activity of the T form relative to that of the G form. These results indicate that A1 transactivates APOE promoter activity by direct and specific interaction with the -219T site.
Campillos
Mónica
M
Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Universidad Autónoma de Madrid, 28049 Cantoblanco, Madrid, Spain.
Lamas
José Ramón
JR
García
Miguel Angel
MA
Bullido
María Jesús
MJ
Valdivieso
Fernando
F
Vázquez
Jesús
J
D000483:Alleles; D001057:Apolipoproteins E / Q000235:genetics*; D001665:Binding Sites; D004265:DNA Helicases / Q000378:metabolism; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D009687:Nuclear Proteins / Q000378:metabolism; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012261:Ribonucleoproteins; D013951:Thymus Hormones / Q000378:metabolism; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D001057:Apolipoproteins E; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D013951:Thymus Hormones; C000619656:hnRNPA1 protein, human; D004265:DNA Helicases