CTCF is essential for up-regulating expression from the amyloid precursor protein promoter during differentiation of primary hippocampal neurons.
The transcriptional mechanism underlying amyloid precursor protein (APP) regulation in primary neurons during development was investigated. We observed an approximately threefold elevation of APP mRNA levels in differentiating rat hippocampal neurons between day 1 and day 7 in culture and in rat brain hippocampi between embryonic day 18 and postnatal day 3. When an APP promoter construct extending to position -2,832 upstream from the main transcriptional start site was transfected into primary rat hippocampal neurons, promoter activity increased from day 1 until reaching a maximum on day 7 in culture. This increase in APP promoter activity was correlated more closely with the time course of expression of the synaptic vesicle protein synaptophysin, an indicator of synaptogenesis, than with neurofilament accumulation, an indicator of neuritogenesis. Transfection of 5' APP promoter deletions and internal block mutations indicated that the CTCF binding domain designated APBbeta was the primary contributor to the increase in APP promoter activity. Furthermore, the binding of transcription factor CTCF to the APBbeta element increased approximately fivefold between day 1 and day 7, whereas the binding of USF to the APBalpha sequence increased only twofold. These results suggest that CTCF is pivotal for the up-regulation of APP expression during synaptogenesis in primary neurons.
Yang
Y
Y
Department of Medical Microbiology and Immunology, Southern Illinois University School of Medicine, Springfield 62794-9626, USA.
Quitschke
W W
WW
Vostrov
A A
AA
Brewer
G J
GJ
D008841:Actin Cytoskeleton / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D000076246:CCCTC-Binding Factor; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology*; D008969:Molecular Sequence Data; D016900:Neurofilament Proteins / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016708:Synaptophysin / Q000096:biosynthesis; D014157:Transcription Factors / Q000502:physiology*
D016564:Amyloid beta-Protein Precursor; D000076246:CCCTC-Binding Factor; D004268:DNA-Binding Proteins; D016900:Neurofilament Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D016708:Synaptophysin; D014157:Transcription Factors