Negative regulation of AbetaPP gene expression by pur-alpha.
The nucleic acid binding protein, Pur-alpha, is best characterized as a transcription factor with affinity to single stranded G/C rich regions. Pur-alpha exhibits developmental and tissue-specific regulation and plays a critical role in neuronal development and differentiation. Similar to Pur-alpha, the amyloid-beta protein precursor (AbetaPP) is a developmentally regulated protein which promotes neuronal survival. Both the human and mouse AbetaPP promoters contain multiple G/C rich sequences which regulate AbetaPP at the transcriptional and translational levels. Using an in vitro reporter assay, we confirmed that Pur-alpha consensus binding sites within the human AbetaPP promoter down-regulate AbetaPP transcription. Electrophoretic mobility shift and chromatin immunoprecipitation assays (ChIP) showed direct binding of Pur-alpha to the AbetaPP promoter. Down regulation of AbetaPP went beyond the transcriptional level as overexpression of Pur-alpha in glial and fibroblast cell lines decreased basal levels of AbetaPP while siRNA targeting Pur-alpha increased basal levels of AbetaPP. Similar findings were observed in brain tissue and fibroblasts from mice with targeted deletion of Pur-alpha. These data point to a novel mechanism of controlling AbetaPP levels by the transcriptional regulatory protein, Pur-alpha, and suggest that Pur-alpha may be involved in the dysregulation of AbetaPP in Alzheimer's disease.
Darbinian
Nune
N
Department of Neuroscience and Center for Neurovirology, Temple University School of Medicine, Philadelphia, PA 19122, USA.
Cui
Jianqi
J
Basile
Anna
A
Del Valle
Luis
L
Otte
Jessica
J
Miklossy
Judith
J
Sawaya
Bassel E
BE
Amini
Shohreh
S
Khalili
Kamel
K
Gordon
Jennifer
J
D000544:Alzheimer Disease / Q000235:genetics*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics*; D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation; D047369:Chromatin Immunoprecipitation; D017931:DNA Primers / Q000235:genetics; D004277:DNA, Single-Stranded / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D005347:Fibroblasts / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D051379:Mice; D009457:Neuroglia / Q000473:pathology; D009474:Neurons / Q000473:pathology; D010957:Plasmids / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics
D016564:Amyloid beta-Protein Precursor; D017931:DNA Primers; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C501130:PURA protein, human; D034741:RNA, Small Interfering; D014157:Transcription Factors