Protein-Based Systems for Translational Regulation of Synthetic mRNAs in Mammalian Cells

Abstract

Synthetic mRNAs, which are produced by in vitro transcription, have been recently attracting attention because they can express any transgenes without the risk of insertional mutagenesis. Although current synthetic mRNA medicine is not designed for spatiotemporal or cell-selective regulation, many preclinical studies have developed the systems for the translational regulation of synthetic mRNAs. Such translational regulation systems will cope with high efficacy and low adverse effects by producing the appropriate amount of therapeutic proteins, depending on the context. Protein-based regulation is one of the most promising approaches for the translational regulation of synthetic mRNAs. As synthetic mRNAs can encode not only output proteins but also regulator proteins, all components of protein-based regulation systems can be delivered as synthetic mRNAs. In addition, in the protein-based regulation systems, the output protein can be utilized as the input for the subsequent regulation to construct multi-layered gene circuits, which enable complex and sophisticated regulation. In this review, I introduce what types of proteins have been used for translational regulation, how to combine them, and how to design effective gene circuits.

Intracellular Molecules Induced Extracellular Peptide Self‐Assembly for Efficient and Effective In Situ Cell Purification

“…Previous works demonstrated that MCP form dimer on the MS2 aptamer. This protein‐aptamer complex can physically hinder the ribosome to repress translation [29,30] . Figure S5 shows that the MCP‐ALP switch with D‐3 treatment induced substantial loss of viability of HEK293 cells, while co‐transfection of MCP mRNA resulted in nearly no loss of viability.…”

“…This protein-aptamer complex can physically hinder the ribosome to repress translation. [29,30] Figure S5 shows that the MCP-ALP switch with D-3 treatment induced substantial loss of viability of HEK293 cells, while co-transfection of MCP mRNA resulted in nearly no loss of viability. Notably, the MCP-Bim switch failed in completely eliminating the HEK293 cells and could not maintain cell viability upon co-transfection of MCP mRNA.…”

Cancer/Testis Antigens as Targets for RNA-Based Anticancer Therapy

“…Unlike DNAbased drugs, mRNA transcripts have a relatively high transfection efficiency and low toxicity because they do not need to enter the nucleus [71]. In addition, mRNAs do not cause insertional mutagenesis [72,73]. A BNT162b2 mRNA vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) did not induce immune-related adverse events in patients with NSCLCs [74].…”

Synthetic Genetic Elements, Devices, and Systems

“…However, for spatiotemporal and cell-specific control, novel methods distinct from DNA transfection are required. Nakanishi reviews protein-based translational regulatory systems for synthetic mRNAs in mammalian cells [ 6 ]. It is noteworthy that the synthetic mRNAs can express both effector proteins and regulatory proteins, allowing for the construction of multilayered genetic circuits composed entirely of mRNAs.…”