Cap 1 Messenger RNA Synthesis with Co-transcriptional CleanCap® Analog by In Vitro Transcription.

Synthetic messenger RNA (mRNA)-based therapeutics are an increasingly popular approach to gene and cell therapies, genome engineering, enzyme replacement therapy, and now, during the global SARS-CoV-2 pandemic, vaccine development. mRNA for such purposes can be synthesized through an enzymatic in vitro transcription (IVT) reaction and formulated for in vivo delivery. Mature mRNA requires a 5'-cap for gene expression and mRNA stability. There are two methods to add a cap in vitro: via a two-step multi-enzymatic reaction or co-transcriptionally. Co-transcriptional methods minimize reaction steps and enzymes needed to make mRNA when compared to enzymatic capping. CleanCap® AG co-transcriptional capping results in 5 mg/ml of IVT with 94% 5'-cap 1 structure. This is highly efficient compared to first-generation cap analogs, such as mCap and ARCA, that incorporate cap 0 structures at lower efficiency and reaction yield. This article describes co-transcriptional capping using TriLink Biotechnology's CleanCap® AG in IVT. © 2021 Wiley Periodicals LLC. Basic Protocol 1: IVT with CleanCap Basic Protocol 2: mRNA purification and analysis.

The tumor suppressor protein HBP1 is a novel c-myc-binding protein that negatively regulates c-myc transcriptional activity.

c-Myc is an important transcription factor that regulates cellular proliferation, cell growth, and differentiation. A number of transcriptional co-factors for c-Myc have been described that have binding sites within highly conserved regions of the c-Myc transactivational domain (TAD). Given the importance of the c-Myc TAD, we set out to identify new proteins that interact with this region using a yeast two-hybrid assay. HBP1 was identified in our screen as a protein that interacts with full-length c-Myc but not a c-Myc mutant lacking the TAD. HBP1 is a transcriptional repressor and has been shown to negatively regulate the cell cycle. A correlation between HBP1 under-expression and breast cancer relapse has been described, suggesting that HBP1 may be an important tumor suppressor protein. We have found that HBP1 binds c-Myc in cells, and expression of HBP1 inhibits c-Myc transactivational activity at least partly by preventing c-Myc binding to target gene promoters. c-Myc binds to the C terminus of HBP1, a region lost in some breast tumors, and some HBP1 mutants found in breast cancer weakly interact with and/or no longer negatively regulate c-Myc. This work adds to our understanding of c-Myc regulation and mechanisms of tumor suppression by HBP1.

A conserved pathway that controls c-Myc protein stability through opposing phosphorylation events occurs in yeast.

The c-Myc transcription factor is a key regulator of cell proliferation and cell fate decisions. c-Myc overexpression is observed in a variety of human tumors, revealing the importance of maintaining normal levels of c-Myc protein. c-Myc protein stability in mammalian cells is controlled by interdependent and sequential phosphorylation and dephosphorylation events on two highly conserved residues, serine 62 and threonine 58. Here we show that these sequential phosphorylation and dephosphorylation events and their effect on c-Myc stability also occurs in the model system Saccharomyces cerevisiae. These results suggest the presence of a conserved pathway in yeast that controls protein turnover in response to a specific phospho-degron sequence. These findings have implications regarding conserved pathways for regulated protein degradation, and they validate the use of genetically tractable yeast for the study of the turnover of proteins such as c-Myc that contain this motif.