Moderate cold exposure extends lifespan and preserves protein health in nematodes through an intertissue metabolic network. Published in Nature, a 2026 study reveals that muscle increases production of dihydrobiopterin, which travels to distant organs and is converted into tetrahydrobiopterin to drive tyrosine-mediated longevity.
Cold Exposure Triggers Intertissue Signals
Moderate cold exposure reshapes metabolism across the body of the nematode Caenorhabditis elegans, according to research published in Nature. Investigators tracked how physical cooling triggers a coordinated physiological response linking muscle tissue to distant organs.
The metabolic pathway starts inside muscle cells. When worms experience cooler surroundings, their muscle tissue increases production of dihydrobiopterin, commonly known as BH2. BH2 travels through the organism to reach recipient organs, including the intestine and the nervous system.
Once the mobile precursor arrives at these distal tissues, cellular machinery converts it into a functional cofactor identified as tetrahydrobiopterin, or BH4. This intertissue transport model demonstrates how a relatively mobile metabolic precursor made in one organ can fulfill metabolic demands elsewhere.
Enzymes Drive Downstream Tyrosine Production
Pinpointing the biochemical drivers required detailed genetic and metabolic mapping. Researchers connected the upstream cold response to CAT-4, the worm counterpart of the human GCH1 enzyme that governs biopterin synthesis.
BH4 serves as an essential cofactor for phenylalanine hydroxylase, designated as PAH-1, which supports tyrosine synthesis. Experiments confirmed that the lifespan extension driven by the BH2–BH4 pathway requires this specific connection. Supplementing worms directly with tyrosine reproduced the longevity benefit at normal temperatures, identifying the PAH-1–tyrosine axis as the true effector rather than treating BH2 as the final endpoint.
Metabolic Signals Preserve Protein Quality
The metabolic cascade impacts far more than sheer lifespan. Elevated BH2 synthesis originating in muscle tissue actively reduces disease-related protein aggregation in distant organs while preserving neuronal and intestinal function as the animals age.
Analyses of ageing populations showed lower accumulation of aggregation-prone proteins. Tissue-specific disruptions confirmed that this protective proteostatic effect relies entirely on continuous communication between muscle and recipient tissues. Tyrosine administration mimicked a portion of this protective response, showing that metabolic signalling coordinates systemic protein quality control rather than operating as isolated cellular maintenance.
Experiments utilized synchronized hermaphrodite adult populations, typically evaluating 96 animals per lifespan condition. Investigators noted that the work establishes a causal pathway primarily within the experimental animal model. Whether similar tissue-to-tissue metabolic transport occurs in mammals or whether direct BH2 delivery can replicate cold-associated benefits without temperature shifts presents an open question for future study.