Scientists can peer into cells to get a limited view of their activity using microscopes and other tools. However, cells and the molecular events within them are dynamic, and developmental processes, disease progression and certain molecular cues are still difficult to discern. Ideally, scientists could leverage a system to obtain an unbiased record of a genome's functional output, showing how cells respond to different conditions over time to gain useful insights. Now, it seems a group of researchers may have found a way to do just that. A new study, published in Science, describes a technique to utilize mysterious cellular structures, called "vault particles," to gather up mRNA by encapsulating and protecting it from degradation. This results in an ability to capture information, like transient stress responses and gene expression changes, and read it out at a later time.
Past approaches for obtaining a cellular recordThis is not the first attempt to measure or record cellular processes over time. However, none have successfully stored an unbiased, time-resolved record of a transcriptome within the same cellular lineage for later retrieval. The researchers say such a system would help to predict long-term outcomes without prior knowledge of which genes to track. However, other approaches have faced various limitations. "Approaches such as RNA sequencing (RNA-seq) are destructive and provide only static snapshots of a cell's state at the time of sampling. Live imaging, while capable of observing biological processes in real time, typically requires continuous optical access and is constrained to tracking a limited number of molecules or reporter constructs," the study authors explain. They say methods like RNA velocity infer gene expression changes but do not directly record them. Meanwhile, approaches like CRISPR-based memory systems and metabolic labeling have limitations in scalability, multiplexing, and stability of recorded information.
Turning vault particles into TimeVaultsThe technique described in the new study leverages vault particles—large ribonucleoprotein particles found in eukaryotic cells, whose role in the cell is still largely unclear—to trap mRNA before it degrades. The resulting structure is what the team refers to as the "TimeVault," which enables stable mRNA storage for over seven days. The encapsulated mRNAs, which convey genetic instructions, are stable, lineage-retained, and can later be retrieved for analysis. To create the TimeVaults, the team added a protein domain that binds to the major vault protein (MVP) in the vault to a binding protein that attaches to mRNA. The binding protein then attaches the captured mRNAs to the interior of the vault. This results in a kind of time capsule of genetic activity. The study authors say the system minimally perturbs cells and allows high-fidelity, transcriptome-wide recording. Normally, RNA degrades relatively quickly, but the study authors say TimeVault effectively shields captured RNAs from normal degradation. Their analysis found that the TimeVault extended mRNA half-life by over sevenfold. "While metabolic labeling provides information on newly transcribed RNA, the tracking window is typically at the timescales of 24 hours due to the short lifetime and fast turnover of the cellular mRNA. In this study, we demonstrated that TimeVault can successfully retrieve past transcriptome states in PC9 cells up to seven days post-transfection, corresponding to six days after recording," the study authors write.
Current abilities and future potentialTo test out TimeVault's abilities, the team performed two experiments: one testing out the measuring of stress responses in living cells by recording endogenous transcriptional responses after exposing them to heat shock and hypoxia, and another recording gene expression changes in rare, drug-resistant lung cancer cell subpopulations. For the first experiment, the study authors say TimeVault successfully captured transient stress responses. "Together with the heat shock recording experiment, these results reinforce TimeVault's ability to accurately capture past
transcriptional states and highlight its specificity in preserving the fidelity of the recorded transcriptome by excluding
gene expression changes occurring after the cessation of recording." In the cancer cell experiment, the vaults were added to lung cancer cells along with a drug to find the protective genes that were active before treatment. This enabled them to target another gene, and use a different drug on this gene. This effectively treated the resistant cancer cells. TimeVault still has some limitations that the team hopes to work on. Currently, only bulk RNA-seq is possible, but integrating with single-cell RNA-seq could enable single-cell, time-resolved transcriptomics in the future. Additionally, the system's recording window is limited to about a week, but longer-term storage may be possible with further engineering. The study authors write, "With continued engineering, TimeVault will enable powerful, time-resolved transcriptomic analysis of complex biological processes such as development, tissue regeneration, and disease progression."
Publication detailsYu-Kai Chao et al, A genetically encoded device for transcriptome storage in mammalian cells, Science (2026). DOI: 10.1126/science.adz9353.
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