Lead poisoning induces nuclear bodies, composed of lead and protein, in many animals including man. These bodies are prominent in renal tubular lining cells. There are well known clinical effects of lead poisoning, but neither the function nor the effect of the nuclear inclusion bodies is known. They may reflect a regulated process which decreases the level of soluble lead. Their formation is blocked in cell culture by inhibitors of RNA and protein synthesis, suggesting that inducible proteins are involved. The inclusion bodies contain a prominent protein which has not been detected elsewhere, suggesting that it is either induced or sequestered by lead. In order to understand inclusion body formation and function, it is necessary to relate the metabolism of these proteins to lead exposure and to study the interactions of the proteins with lead. The chemical properties of the inclusion bodies impose severe restraints on their study. A cell culture system will be used in correlating synthesis of inclusion body proteins with lead exposure. Further, the synthesis of the cognate mRNA's will be determined by an in vitro translation assay in order to confirm induction by lead. The tendency of these proteins to bind lead will be studied by exposure of purified, bound protein to soluble radioactive lead. Monoclonal antibodies will be prepared and used for assaying and purifying the proteins and in characterizing their intracellular location(s). Complementary DNA clones will be isolated in order that regulation of gene activity can be studied quantitatively in various cells and under various stimuli such as lead, other metals, and other traumatic effects such as heat. The effects of lead on cells have been difficult to study at the molecular level. However, the application of recently developed procedures to a study of the long recognized nuclear inclusion bodies provides a unique opportunity to study this problem.
