DESCRIPTION (provided by applicant): The major long-term objectives of the proposed research are [1] to test the hypothesis that lead interacts with calcium binding proteins of the C2 and annexin families, and [2] to identify genes and proteins of these calcium-binding families that are regulated following lead exposure of rats. Lead poisoning remains a pervasive problem in the United States, affecting at least 5% of all children. The proposed research is intended to elucidate molecular mechanisms underlying lead toxicity. Previous studies have demonstrated potent interactions between lead and proteins of the C2 domain family (e.g. protein kinase C and synaptotagmin) and annexins. Furthermore, lead exposure of cells has been shown to regulate the expression of genes encoding calcium-binding annexins. The four specific aims of this proposal are [1] to measure the interactions of lead with proteins of the C2 domain and annexin families, in order to determine the possible targets of lead. [2] To measure gene expression in the brain, kidney and liver of lead-exposed rats. This in vivo model may reveal whether lead exposure differentially regulates the expression of genes encoding calcium-binding proteins. [3] To extend gene expression studies to well characterized cell lines (astrocytes, PC12 cells, fibroblasts and normal rat kidney cells). These studies will complement gene expression measurements from the in vivo model. [4] To deposit gene expression data into a publicly accessible database. Together these studies may reveal which calcium binding proteins interact with lead, and which genes encoding calcium-binding proteins are regulated by lead exposure.