The long-term objectives of this research program are: 1) to identify the cause of the faulty secretion of alpha-1-proteinase inhibitor (A1-Pi) observed in individuals suffering from A1-Pi deficiency and 2) to develop approaches toward therapy for this disease that can be used for the prevention and treatment of the associated pulmonary emphysema. This proposal contains plans for the use of genetic techniques to generate models for use in the study of potential causes of A1-Pi deficiency. Two genetic approaches for production of these models will be used: 1) Standard somatic cell genetic techniques will be used to produce and isolate mutants of human hepatoma (Hep G-2) cells that synthesize but fail to secrete or secrete subnormal levels of A1-Pi; 2) Expression of wild type or mutated forms of the A1-Pi gene and secretion of the resulting gene products will be monitored in mammalian cells transfected with appropriate A1-Pi cDNA containing vectors. Biochemical and genetic analyses of the mutant hepatoma cells will yield information relevant to the critical steps in the processing and secretion of A1-Pi and to the number of gene products required for this process. The studies on the expression of altered A1-Pi cDNA genes will show which features of the A1-Pi protein sequence are required for its normal secretion. Successful completion of this project will provide a detailed description of the normal pathway for secretion of A1-Pi and should produce a thorough understanding of the defect that causes A1-Pi deficiency. This information will allow a rational approach to the design of appropriate therapy for this disease.