TNFR-associated factor-2 (TRAF-2) in Alzheimer's disease

Levels of tumor necrosis factor-alpha (TNF-alpha) are increased in the brain in Alzheimer's disease (AD). The TNF-alpha/TNF-R signaling pathways involve complex interactions between several proteins, including TNF-receptor-associated factor-2 (TRAF-2). We have examined the distribution and levels of TRAF-2 in AD and control brains and also whether single nucleotide polymorphisms (SNPs) in the TRAF-2 gene are associated with AD and influence TRAF-2 expression. Immunohistochemistry demonstrated TRAF-2 in AD and control cortex in neurons, within plaque-associated neurites and some neurofibrillary tangles. Western blots revealed a band of the expected apparent molecular mass (approximately 50kDa) for TRAF-2, in homogenates of AD and control cortex. RT-PCR showed the levels of TRAF-2 mRNA to be significantly higher in the frontal cortex of AD than control brains (p=0.015). TRAF-2 mRNA expression was not linked to any SNPs. The 3' UTR SNP (rs7852970) GG allele was significantly protective against AD (p=0.030). Our findings suggest that the TRAF-2 pathway is involved AD. The mechanisms are currently unclear and need further examination.