P3‐025: Fyn regulatory region haplotype specific expression

Evidence suggests that Fyn, a tyrosine kinase, may be involved in aberrant tau phosphorylation in AD and is elevated in AD brain compared to controls. Extracellular oligomeric Aβ, cellular prion protein and Fyn coupling are implicated in an intracellular signaling cascade which may in turn influence tau expression. Our previous study found an association between a SNP in the 5’ region of FYN and cerebrospinal fluid (CSF) tau levels in AD suggesting that FYN regulatory region genetic content may play a role in AD elevated CSF tau. Since it has been proposed that FYN expression might be a target for AD therapeutic strategies, it is important to tease apart the cis-acting functional components of this genetic signal. The hypothesis of this investigation was that FYN expression and promoter activity are significantly influenced according to genetic content. The objective of this investigation was to produce a library of FYN regulatory region haplotype reporter constructs and compare their expression in multiple human neuronal and astroglial cell lines. The FYN promoter and 3’ region of 3 different FYN isoforms (from genomic DNA) were inserted into reporter vectors in various haplotype combinations. This created 9 FYN promoter regulatory region haplotype reporters and 24 FYN promoter plus 3’UTR regulatory region haplotype reporters. A total of 33 regulatory region haplotype reporters were transfected into multiple human cell lines to compare their expression. Results indicate that there is a significant difference in: 1) FYN isoform activity that varies according to cell type, 2) FYN promoter activity variation according to haplotype and cell type and 3) 3’ UTR inhibition of promoter activity according to haplotype. These results suggest that FYN expression is significantly influenced by regulatory region genetic content. Teasing apart the cis-acting functional components of AD genes, such as FYN, will enhance our knowledge of AD as well as inform AD prediction and therapeutic modalities.