Metformin Extends Lifespan by Rewiring Chromatin and Silencing Mobile DNA

Metformin is one of the most prescribed drugs in the world, yet scientists still debate exactly how it slows aging at the cellular level. Most research has focused on its effects on metabolic signaling pathways like AMPK and mTOR, but this new study suggests that chromatin regulation and mobile genetic elements play an equally important role.

Researchers at Cinvestav and UNAM used Saccharomyces cerevisiae — baker's yeast — as a model for chronological aging, the biological equivalent of how long non-dividing cells survive. They applied high-resolution genetic profiling to map which gene deletions interact with metformin treatment to alter lifespan, revealing a surprisingly strong cluster of interactions involving chromatin modification genes.

The most striking finding involved Set3C, a histone deacetylase complex. Genetically impairing Set3C produced lifespan changes that closely mimicked those caused by metformin, implying the two converge on a shared regulatory pathway. RNA sequencing then showed that metformin dramatically reshapes gene expression in stationary-phase yeast, with the clearest signal coming from Ty1-copia retrotransposons — ancient, virus-like mobile DNA elements embedded in the genome.

Critically, despite elevated Ty1 transcripts, metformin actually reduced the Gag-like protein encoded by Ty1 and did not increase DNA insertion events. This uncoupling of transcription from mobility suggests the cell actively suppresses retrotransposon activity at a post-transcriptional level. Proteomics data further identified early upregulation of mitochondrial and stress-response proteins — both known to influence Ty1 dynamics — hinting at a coordinated cellular program.

These results expand metformin's known mechanisms into the realm of epigenetics and genome stability. While this work is in yeast, retrotransposon derepression is a recognized hallmark of mammalian aging, making the findings potentially translatable. Caution is warranted until mammalian validation is complete.