Regulation of Expression of the Human Proenkephalin Gene in Heterologous Cell Systems

Abstract

Gene transfer studies allow for different aspects of the regulation of neuropeptide gene expression to be studied. Stable integration of the human proenkephalin gene into the genome of a mouse pituitary cell line (AtT-20) results in the accurate transcription of the proenkephalin gene. Protein analysis revealed that the translated proenkephalin is accurately cleaved to mature Met-enkephalin peptides. A second gene transfer approach used to study the processing pathway of precursor proteins is to transiently express the proenkephalin mRNA directly into the cell cytoplasm. The unique biology of vaccinia virus allows for this type of study. Infection of a variety of cell lines with a recombinant vaccinia virus containing the human proenkephalin gene lead to rapid expression and secretion of human proenkephalin. Of all cell lines tested, only AtT-20 cells possessed the capacity to cleave human proenkephalin to small enkephalin peptides.