The present invention features a nucleic acid construct for expressing a product, e.g., a small peptide such as GLP-1. The construct includes a nucleic acid sequence encoding a signal peptide and a nucleic acid sequence which encodes the pro-region of somatostatin or a functional fragment thereof. The construct can further include a sequence encoding the small peptide or the construct can be used to express an endogenous genomic sequence encoding the small peptide. The present invention further features genetically engineered cells, and methods of using such constructs or cells.