title: Regulation of alpha-synuclein expression by poly (ADP ribose) polymerase-1 (PARP-1) binding to the NACP-Rep1 polymorphic site upstream of the SNCA gene.
abstract: Alleles at NACP-Rep1, the polymorphic microsatellite repeat located approximately 10 kb upstream of the alpha -synuclein gene (SNCA), are associated, in some reports, with differing risks of sporadic Parkinson disease (PD). We showed previously that NACP-Rep1 acts as a negative modulator of SNCA transcription, with an effect that varied threefold among different NACP-Rep1 alleles. Given that duplications and triplications of SNCA have been implicated in familial Parkinson disease (PD), even a 1.5-2-fold increase in alpha -synuclein expression may, over many decades, contribute to PD. Thus, the association of different NACP-Rep1 alleles with PD may be a consequence of polymorphic differences in transcriptional regulation of SNCA. Here we aimed to identify the factor(s) that bind to NACP-Rep1 and potentially contribute to SNCA transcriptional modulation, by pulling down proteins that bind to NACP-Rep1 and identifying them by mass spectrometry. One of these proteins was poly-(ADP-ribose) transferase/polymerase-1 (PARP-1), a DNA-binding protein and transcriptional regulator. Electrophoresis mobility shift and chromatin immunoprecipitation assays showed specific binding of PARP-1 to NACP-Rep1. Inhibition of PARP-1's catalytic domain increased the endogenous SNCA mRNA levels in cultured SH-SY5Y cells. Furthermore, PARP-1 binding to NACP-Rep1 specifically reduced the transcriptional activity of the SNCA promoter/enhancer in luciferase reporter assays. This down-regulation effect of PARP-1 depended on NACP-Rep1 being present in the construct and was abrogated by inhibiting PARP-1's catalytic activity with 3-aminobenzamide. The association of different NACP-Rep1 alleles with PD may be mediated, in part, by the effect of PARP-1, as well as other factors, on SNCA expression.
authors.affiliation: Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Ornit
authors.initials: O
authors.lastname: Chiba-Falek
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Kowalak
authors.forename: Mark E
authors.initials: ME
authors.lastname: Smulson
authors.forename: Robert L
authors.initials: RL
authors.lastname: Nussbaum
mesh_terms: D000483:Alleles; D001483:Base Sequence; D001549:Benzamides / Q000494:pharmacology; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D018895:Microsatellite Repeats; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D010300:Parkinson Disease / Q000235:genetics; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D011110:Polymorphism, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051843:Synucleins; D051844:alpha-Synuclein
chemical_list: D001549:Benzamides; D004791:Enzyme Inhibitors; D009419:Nerve Tissue Proteins; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D012333:RNA, Messenger; C497604:SNCA protein, human; D051843:Synucleins; D051844:alpha-Synuclein; C025160:3-aminobenzamide; D004247:DNA; D011065:Poly(ADP-ribose) Polymerases