Developmental exposure to lead (Pb) alters the expression of the human tau gene and its products in a transgenic animal model.

Tauopathies are a class of neurodegenerative diseases associated with the pathological aggregation of the tau protein in the human brain. The best known of these illnesses is Alzheimer's disease (AD); a disease where the microtubule associated protein tau (MAPT) becomes hyperphosphorylated (lowering its binding affinity to microtubules) and aggregates within neurons in the form of neurofibrillary tangles (NFTs). In this paper we examine whether environmental factors play a significant role in tau pathogenesis. Our studies were conducted in a double mutant mouse model that expressed the human tau gene and lacked the gene for murine tau. The human tau mouse model was tested for the transgene's ability to respond to an environmental toxicant. Pups were developmentally exposed to lead (Pb) from postnatal day (PND) 1-20 with 0.2% Pb acetate. Mice were then sacrificed at PND 20, 30, 40 and 60. Protein and mRNA levels for tau and CDK5 as well as tau phosphorylation at Ser396 were determined. In addition, the potential role of miRNA in tau expression was investigated by measuring levels of miR-34c, a miRNA that targets the mRNA for human tau, at PND20 and 50. The expression of the human tau transgene was altered by developmental exposure to Pb. This exposure also altered the expression of miR-34c. Our findings are the first of their kind to test the responsiveness of the human tau gene to an environmental toxicant and to examine an epigenetic mechanism that may be involved in the regulation of this gene's expression.

Tolfenamic acid interrupts the de novo synthesis of the ß-amyloid precursor protein and lowers amyloid beta via a transcriptional pathway.

Amyloid beta (Aß) peptides are related to the pathogenesis of Alzheimer's disease (AD). The search for therapeutic strategies that lower these peptides has mainly focused on the proteolytic processing of the ß-amyloid precursor protein (APP), and other post-transcriptional pathways. The transcription factor specificity protein 1 (Sp1) is vital for the regulation of several genes involved in AD including APP and the beta site APP cleaving enzyme 1 (BACE1). We have previously reported that tolfenamic acid promotes the degradation of Sp1 protein (SP1) in pancreatic human cancer cells and mice tumors. This study examines the ability of tolfenamic acid to reduce SP1 levels, and thereby decrease APP transcription and Aß levels in rodent brains. Tolfenamic acid was administered by oral gavage to C57BL/6 mice at variable dosages and for different time periods. Results have shown that tolfenamic acid was able to down regulate brain protein levels of SP1, APP, and Aß. These findings demonstrate that interference with upstream transcriptional pathways can lower pathogenic intermediates associated with AD, and thus tolfenamic acid represents a novel approach for the development of a therapeutic intervention for AD.