In obese mice, a drug called G49 boosts calorie burning and activates fat tissue that generates heat, but this effect only occurs if the protein UCP1 is present; without UCP1, the drug fails to...
Mechanism
Synthesis from 1 study
G49 makes fat cells release fuel, which tells the liver to send a signal that wakes up brown fat. That brown fat uses a special protein called UCP1 to burn the fuel and make heat instead of storing energy. Without that protein, the body can’t burn extra calories or lose weight—even if the fuel and...
Most probable mechanism
The drug G49 triggers fat cells to release fatty acids, which signal the liver to produce a hormone called FGF21. FGF21, along with nerve signals from the brain, tells brown fat cells to turn on a protein called UCP1. This protein lets the brown fat burn fatty acids to make heat instead of storing energy, which increases calorie burning and causes weight loss. Without UCP1, this heat-making process stops, even if fatty acids and FGF21 are still high.
G49 binds to glucagon receptors on white adipose tissue, activating PKA and phosphorylating hormone-sensitive lipase to trigger lipolysis and release of free fatty acids into circulation
Free fatty acids are taken up by the liver, activating PPARα and CPT1a to drive fatty acid oxidation and ketogenesis, which stimulates FGF21 transcription and secretion
Secreted FGF21 acts on brown adipose tissue to upregulate UCP1 expression, synergizing with sympathetic nervous system activation to enhance thermogenic gene expression
UCP1 protein inserts into the mitochondrial inner membrane of brown adipocytes, uncoupling the proton gradient from ATP synthesis to dissipate energy as heat
Loss of UCP1 abolishes increased energy expenditure and weight loss despite preserved lipolysis and elevated FGF21, confirming UCP1 is necessary for thermogenic output
Evidence from Studies
Supporting (1)
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The dual GLP-1/glucagon receptor agonist G49 mimics bariatric surgery effects by inducing metabolic rewiring and inter-organ crosstalk
Contradicting (0)
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