Researchers have discovered a surprising mechanism by which viral infections can sabotage cellular function. When excessive RNA builds up inside a cell, it can damage the structures responsible for energy production, leaving the cell unable to operate normally.
A study led by scientists at the Texas A&M College of Veterinary Medicine and Biomedical Sciences (VMBS) reveals that surplus RNA generated during poxvirus infections can harm mitochondria—the organelles that supply most cellular energy. The findings were published in *Proceedings of the National Academy of Sciences*.
The research highlights an unexpected link between RNA accumulation and cellular energy generation, offering insights that may extend beyond viruses. These results could improve understanding of aging‑related diseases and aid the development of RNA‑based medical therapies, including mRNA vaccines.
“RNA degradation has long been known to regulate protein synthesis and clear defective RNA,” said Dr. Zhilong Yang, a professor in VMBS’s Department of Veterinary Pathobiology. “Our work shows it also safeguards cellular energy levels, a critical function for cell health.”
Cells continuously synthesize and degrade RNA as part of normal metabolism. This turnover controls protein output, eliminates faulty transcripts, modulates immune responses, and, as the study shows, protects mitochondrial function.
Why Too Much RNA Damages Cells
RNA performs several essential roles in cellular operations. Messenger RNA (mRNA) carries genetic instructions that direct protein synthesis—proteins that support virtually every cellular activity. Another form, double‑stranded RNA (dsRNA), often appears during viral infections and can trigger immune alarms.
Viruses replicate by producing large quantities of RNA within infected cells. While cellular clearance systems normally prevent harmful buildup, an overload can overwhelm these defenses. Excess RNA can then interfere with mitochondria, reducing energy output.
Previously, scientists recognized that high levels of dsRNA could provoke harmful immune reactions. This study unexpectedly demonstrates that even abundant mRNA—normally a benign cellular component—can impair mitochondria when present in excess.
“MRNA is a normal part of our cells, but like many good things, too much of it can become problematic,” Yang explained. “When mRNA accumulates, it can damage mitochondria and hinder the cell’s ability to generate energy.”
This paradox creates a challenge for viruses. Although viruses rely on host cell energy and protein‑making machinery, producing too much viral RNA can damage the very systems they need for replication. Poxviruses, which cause diseases such as smallpox and mpox, appear to manage this by employing cellular RNA‑cleanup mechanisms to keep levels in check.
“If the cell is not healthy, the virus would not replicate well,” Yang noted. “Balancing RNA levels is crucial for viral success.”
Direct Impact of Excess RNA on Mitochondria
The study’s most striking observation came when researchers examined how surplus RNA affects mitochondria directly. Initially, they hypothesized that RNA buildup triggered immune pathways that indirectly harmed mitochondria.
However, experiments isolating mitochondria and adding RNA alone still showed mitochondrial damage, indicating a direct effect independent of immune activation.
“When we isolated only the mitochondria and added RNA, we still saw mitochondrial damage,” said Dr. Djamal Brahim Belhaouari, the study’s first author. “This revealed a previously unknown cellular response to RNA.”
Mitochondrial dysfunction appeared before significant immune signaling, and the damage occurred without the usual infection‑related immune pathways. Together, these data suggest that excess RNA itself can disrupt mitochondrial function.
While the exact mechanism remains unclear, the researchers propose an electrical explanation. Mitochondria generate energy by maintaining an electrical gradient across their inner membranes. RNA carries a negative charge; large amounts accumulating near mitochondria could disturb this gradient, impairing ATP production.
“We suspect that the negatively charged RNA may build up around mitochondria and interfere with the electrical balance needed for energy production, though the precise process is still unknown,” Yang said. “This is a new concept we are actively exploring.”
Broader Implications for Aging, Disease, and RNA Therapies
Although the experiments focused on viral infections, the findings raise the possibility that RNA accumulation contributes to other health conditions. Abnormal RNA buildup has been observed in certain cancers, neurodegenerative disorders, and aging‑related diseases.
Because mitochondria are vital for cellular health, disruptions to their energy production could play a role in the cellular dysfunction seen in these diseases. The study suggests that excess RNA may be an overlooked source of mitochondrial stress.
“We think this has quite broad translational implications,” Brahim Belhaouari noted. “Ineffective degradation of excess dsRNA or mRNA may contribute to disease processes in various contexts.”
Relevance for mRNA Vaccines and Future RNA‑Based Treatments
The discovery also offers valuable insights for the design of RNA‑based medicines, including mRNA vaccines. These therapies introduce RNA into cells to instruct protein production. Understanding how cells manage RNA levels and the potential consequences of overload is essential for optimizing safety and efficacy.
While the study does not indicate that current mRNA vaccines cause mitochondrial damage in humans, it highlights the importance of RNA regulation for cellular health. “Gaining a clearer picture of how cells respond to large RNA amounts could help researchers refine future RNA therapeutics and vaccines,” Yang added.
Overall, the research underscores that even essential molecules like RNA can become harmful when their concentration exceeds normal limits, emphasizing the critical role of RNA homeostasis in maintaining cellular energy and health.