mRNA Synthesis and Encapsulation in Ionizable Lipid Nanoparticles.

mRNA vaccines have recently generated significant interest due to their success during the COVID-19 pandemic. Their success is due to advances in mRNA design and encapsulation into ionizable lipid nanoparticles (iLNPs). This has highlighted the potential for the use of mRNA-iLNPs in other settings such as cancer, gene therapy, or vaccines for different infectious diseases. Here, we describe the production of mRNA-iLNPs using commercially available reagents that are suitable for use as vaccines and therapeutics. This article contains detailed protocols for the synthesis of mRNA by in vitro transcription with enzymatic capping and tailing and the encapsulation of the mRNA into iLNPs using the ionizable lipid DLin-MC3-DMA. DLin-MC3-DMA is often used as a benchmark for new formulations and provides an efficient delivery vehicle for screening mRNA design. The protocol also describes how the formulation can be adapted to other lipids. Finally, a stepwise methodology is presented for the characterization and quality control of mRNA-iLNPs, including measuring mRNA concentration and encapsulation efficiency, particle size, and zeta potential. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Synthesis of mRNA by in vitro transcription and enzymatic capping and tailing Basic Protocol 2: Encapsulation of mRNA into ionizable lipid nanoparticles Alternate Protocol: Small-scale encapsulation of mRNA using preformed vesicles Basic Protocol 3: Characterization and quality control of mRNA ionizable lipid nanoparticles.

PP2A Phosphatase as an Emerging Viral Host Factor.

Protein phosphatase 2A (PP2A) is one of the most ubiquitous cellular proteins and is responsible for the vast majority of Ser/Thr phosphatase activity in eukaryotes. PP2A is a heterotrimer, and its assembly, intracellular localization, enzymatic activity, and substrate specificity are subject to dynamic regulation. Each of its subunits can be targeted by viral proteins to hijack and modulate its activity and downstream signaling to the advantage of the virus. Binding to PP2A is known to be essential to the life cycle of many viruses and seems to play a particularly crucial role for oncogenic viruses, which utilize PP2A to transform infected cells through controlling the cell cycle and apoptosis. Here we summarise the latest developments in the field of PP2A viral targeting; in particular recent discoveries of PP2A hijacking through molecular mimicry of a B56-specific motif by several different viruses. We also discuss the potential as well as shortcomings for therapeutic intervention in the face of our current understanding of viral PP2A targeting.