Development of biological systems for the controlled rapid release of proteins from cells
The secretion of soluble proteins or the movement of transmembrane proteins to the cell plasma membrane is a key feature of multicellular organisms, particularly for communication between cells and the regulation of important processes, such as the release of insulin upon elevated blood glucose level, blood pressure regulation with hormones, as well as defense against viral infection by the release of cytokines and interferons etc. Several natural mechanisms rely on rapidly releasing a protein upon the presence of an appropriate signal. Currently designed systems for controlling protein secretion mostly rely on regulating protein expression, a process which takes several hours before the protein is synthesized and secreted in an amount necessary to elicit its biological function.
Researchers from the Department for synthetic biology and immunology at the National Institute of Chemistry published an article in the journal Nature communications with the title Regulation of protein secretion through chemical regulation of endoplasmic reticulum retention signal cleavage, in which they developed two systems termed lumER and membER, for the controlled secretion of proteins, which are able to release therapeutic proteins from the cell in minutes rather than hours.
The two developed systems bypass the need for prior transcription and translation of a target protein and instead rely on storing pre-synthesized proteins in the cells secretory pathway, similar to natural biological systems, where a response needs to occur rapidly (for example in the release of hormones and cytokines). The release of the protein of interest from the cell is controlled by the removal of a peptide retention sequence by chemically regulated proteases, which allows the proteins to exit the endoplasmic reticulum and reach the plasma membrane or the cells exterior. The use of modular protein elements also allows for the processing of input signals according to two-input Boolean logic functions. The applicability of the system was demonstrated by controlling the release of human insulin, the anti-inflammatory cytokine IL-10 and controlling the activity of CAR T-cells, which are used in cancer immunotherapy.
The authors of the study are Arne Praznik, Tina Fink, Nik Franko, Jan Lonzarić, Mojca Benčina, Nina Jerala, Tjaša Plaper, Samo Roškar and Roman Jerala.