irisin

^[1]^[2]

Function

cleaved & secreted from membrane protein FNDC5^[1]
irisin acts on white adipose cells to stimulate UCP1 expression & a broad program of brown-fat-like development
irisin is induced with exercise in humans

mildly increased irisin levels in the blood cause an increase in energy expenditure in mice with no changes in movement or food intake
- this results in improvements in obesity & glucose homeostasis
regular exercise improves cognition & induces irisin in mice
- irisin knockout mice do not show improved cognition with exercise
- injecting irisin into the hippocampus improved memory^[2]

↑ ^1.0 ^1.1 Bostrom P et al. A PGC1-alpha-dependent myokine that drives brown-fat-like development of white fat and thermogenesis. Nature 2012 Jan 26; 481:46 PMID: https://www.ncbi.nlm.nih.gov/pubmed/22237023
↑ ^2.0 ^2.1 Islam MR, Valaris S, Young MF et al. Exercise hormone irisin is a critical regulator of cognitive function. Nat Metab 2021 Aug; 3:1058 PMID: https://www.ncbi.nlm.nih.gov/pubmed/34417591 https://www.nature.com/articles/s42255-021-00438-z