A highly efficient modified human serum albumin signal peptide to secrete proteins in cells derived from different mammalian species

- The same SP (mSA) might be used to express proteins in different mammalian cells.
- The mSA SP is efficient to direct secretion of active proteins in stable and transient conditions.
- The SP efficiency is not influenced by the transgene copy number.

Signal peptides (SPs) are key elements in the production of recombinant proteins; however, little information is available concerning different SP in mammalian cells other than CHO. In order to study the efficiency of different SPs to direct the traffic along the secretory pathway of the green fluorescence protein (GFP) and a scFv-Fc fusion protein; CHO-K1, HEK293 and NS0 cell lines were transfected in a transient and stable way. SP of human azurocidin (AZ), modified human albumin (mSA), modified Cricetulus griseus Ig kappa chain V III region MOPC 63 like (mIgκ C) and modified human Ig kappa chain V III region VG (mIgκ H) were evaluated. The efficiency of SPs to translocate a propeptide across the ER membrane was evaluated by fluorescence microscopy and flow cytometry for the GFP inside the secretory pathway, and by antigen-specific indirect ELISA for the scFv-Fc outside the cell. The mSA SP was successful in directing the secretion of the active proteins in these different types of mammalian cells, regardless of the transgene copy number. The goal of this work was to demonstrate that a modified version of SA SP might be used in different mammalian cells employing the same expression vector.