The Futile Creatine Cycle powers UCP1-independent thermogenesis in classical BAT.
Level 5 - mechanism / opinion, no new human data
Animal/preclinical research using mouse genetic models with no human data
PubMed 40185737 · doi:10.1038/s41467-025-58294-4
What was done
Researchers investigated whether the futile creatine cycle (FCC)—mediated by mitochondrial creatine kinase B (CKB) phosphorylation and tissue-nonspecific alkaline phosphatase (TNAP) phosphocreatine hydrolysis—acts as an uncoupling protein 1 (UCP1)-independent thermogenic pathway in classical brown adipose tissue (BAT). They tested cold tolerance and thermogenesis in mouse models lacking native UCP1 and CKB with mitochondrial-targeted CKB reintroduced into interscapular brown adipocytes, and in mice with inducible adipocyte-specific co-deletion of TNAP and UCP1.
What was found
No quantitative values or sample sizes are reported in the abstract. Reintroduction of mitochondrial-targeted CKB into interscapular brown adipocytes restored thermogenesis and cold tolerance in UCP1- and CKB-knockout mice through a TNAP-dependent mechanism, whereas mice with combined adipocyte-specific deletion of TNAP and UCP1 showed severe cold intolerance.
Why it matters
These findings challenge the dogma that classical BAT thermogenesis relies exclusively on UCP1-mediated proton leak, establishing the futile creatine cycle as a physiologically relevant alternative thermogenic mechanism.
Limits
The study is restricted to transgenic mouse models, and relevance to human brown fat physiology remains unproven. Sample sizes, quantitative changes in body temperature, and metabolic expenditure rates are not reported in the abstract.
Cited by
- supports In animal models, creatine has been shown to have beneficial effects on fat from a cellular perspective.