Structural and functional characterization of H2 haplotype MAPT promoter: Unique neurospecific domains and a hypoxia–inducible element would enhance rationally targeted tauopathy research for Alzheimer’s disease

摘要

Alzheimer’s disease (AD) is the leading cause of dementia in the elderly. Extraneuronal plaque consisting primarily of amyloid β peptide and intraneuronal tangles of hyperphosphorylated microtubule–associated τ protein (τ, gene MAPT) are typical of AD. Misfolded τ is also implicated in Parkinson’s disease and frontotemporal dementia. We aim to understand the regulation of the human MAPT promoter by mapping its functional domains. We subcloned a 4868 base pair fragment from human BAC RPCI–11 100C5. Sequence analysis revealed an H2 haplotype MAPT promoter, 5′–UTR, and intronal fragment. Database analysis of the fragment showed 50%–75% homology with mouse and >90% with rhesus monkey. Comparison with human H1 sequences revealed differences that crossed predicted transcription factor sites. DNA–protein interaction studies by electrophoretic mobility shift assay suggested an active specificity protein 1 (SP1) site in the 5′–untranslated region and hypoxia response. Transfection of a series of MAPT promoter deletions revealed unique functional domains. The distal–most had different response in neuronal vs. non–neuronal cells. We have cloned, sequenced, and functionally characterized a 4868 bp fragment of the human MAPT 5′–flanking region, including the core promoter region (−302/+4), neurospecific domains (−4364/−1992 and +293/+504, relative to +1 TSS), and a hypoxia–inducible element (+60/+84). Our work extends functional analysis of the MAPT sequence further upstream, and explores cell–type specificity of MAPT promoter activity. Finally, we provided direct comparison of likely transcription factor binding sites, which are useful to understand differences between H1/H2 pathogenic associations.