Scientists Find Possible New Route to More Powerful mRNA Drugs
核心洞察
Johns Hopkins Medicine (搜索) researchers identified N4-acetylcytidine (ac4C) (搜索), a naturally occurring RNA modification, as a potential way to make mRNA therapies produce more protein inside cells.
Ribosomes traveled nearly twice as fast on ac4C-modified mRNA compared with the industry-standard N1-methylpseudouridine (m1Ψ) (搜索) platform, preventing ribosomal "traffic jams."
The ac4C platform produced more and better proteins, suggesting future mRNA drugs could achieve therapeutic effects with smaller doses.
Scientists at Johns Hopkins Medicine (搜索) have identified a potential way to make mRNA therapies produce more protein inside cells, a finding that could eventually influence vaccines and treatments for cancer (搜索), infectious diseases (搜索) and autoimmune conditions (搜索).
The research, published in Nature, focuses on a naturally occurring RNA modification called N4-acetylcytidine, or ac4C. Today, the leading mRNA platform relies on a different modification, N1-methylpseudouridine, or m1Ψ — the technology used in the COVID-19 mRNA vaccines and now being studied for other medical applications.
"Our results show that ac4C causes cells to produce more therapeutic proteins to fight disease than the industry standard mRNA platform," said Bin Wu, associate professor of biophysics and biophysical chemistry at the Johns Hopkins University School of Medicine. "This may eventually lead to more efficient drugs that require smaller doses."
A Faster Ribosome on the ac4C Platform
There are more than 170 known RNA modifications, but only a small subset of those have been studied for mRNA therapeutic purposes, Wu says. ac4C may enhance mRNA translation, thereby having the potential to speed up and build proteins.
Inside cells, ribosomes move along strands of mRNA, reading the genetic instructions and assembling proteins. The Johns Hopkins team found that ribosomes moving along ac4C-modified mRNA travelled nearly twice as fast as those working on m1Ψ-modified mRNA.
The difference, the scientists say, may resemble a traffic problem. "Our imaging revealed that ribosomes travel nearly twice as fast on the ac4C-modified mRNA, preventing the ribosomal traffic jam we may encounter with the industry standard mRNA platform," Wu says.
While m1Ψ is a safe and effective mechanism for drug delivery, the researchers say this study reveals how ribosomes that travel along single strands of mRNA containing m1Ψ may slow down and cause traffic jams, which in turn creates less protein that triggers an immune response.
Experimental Design and Imaging
In their experiments, the scientists used lipid nanoparticles to mimic how vaccines work, inserting the mRNA modifications — ac4C and the industry m1Ψ — into cultured human dendritic cells derived from monocytes, or white blood cells that support the immune system, and mouse liver cells.
Comparing the two mRNA modifications, the scientists used an imaging technique developed by Wu's lab, called single-molecule imaging of nascent peptides, using an advanced microscope to track individual mRNAs as they produced therapeutic proteins within the cells.
Further, Wu says, the imaging demonstrated that these irregularly translated ribosomes on the m1Ψ platform caused premature termination or frameshifting, making less or compromised proteins. In contrast, the ac4C platform resulted in smoother mRNA translation, preventing ribosomal roadblocks and producing more and better proteins that may boost therapeutic effects.
"We propose this ribosome collision as a model for why the industry standard may create less proteins," Wu says. "In the future, this could help us investigate potential therapeutics that require smaller doses, but which create more protein and a better immune response."
Implications for the mRNA Pipeline
That could have significant implications for the mRNA industry if the finding holds up in further research. One of the attractions of mRNA technology is its ability to instruct cells to temporarily produce a particular protein. But the amount of protein produced can be critical to whether a therapy works effectively.
If researchers can get cells to make more protein from the same amount of mRNA, future therapies might potentially achieve their desired effects with smaller doses. That could matter across a growing mRNA pipeline, including vaccines targeting infectious diseases (搜索) and experimental therapies designed to stimulate the immune system against cancer (搜索) or alter immune responses in autoimmune disease.
The study, funded and co-led by the NIH, was published July 1 in Nature. The research began when co-corresponding author Shalini Oberdoerffer, Ph.D., senior investigator in the Laboratory of Receptor Biology and Gene Expression at the National Cancer Institute, gave a talk about ac4C at Johns Hopkins University in 2024. Wu, who uses biophysics to study mechanisms of mRNA modifications, proposed a research collaboration to better understand the behavior of individual RNA molecules.
For now, ac4C remains experimental. But if the molecular "traffic jam" identified by the researchers turns out to be a meaningful limitation of today's mRNA platforms — and if ac4C can overcome it safely in living organisms — the discovery could become an important piece of the race to build the next generation of mRNA medicines.