In obese mice, a single injection of a specific drug causes fat cells to break down stored fat, releasing fatty acids into the blood. This triggers a series of metabolic changes in the liver and...
Mechanism
Synthesis from 1 study
The drug makes fat cells release fatty acids, which tell the liver to start burning fat and produce a signal that turns on heat-burning brown fat. This burns extra calories and leads to lasting weight loss. Other processes like immune cell activity and liver hormone signals help make this effect...
Most probable mechanism
The drug tells fat cells to break down stored fat into fatty acids, which flood the liver. The liver uses those fatty acids to make ketones and a signal molecule called FGF21. FGF21 then tells brown fat to turn on its heat-burning mode, which uses up extra energy and leads to lasting weight loss.
G49 binds to glucagon receptors on white adipose tissue adipocytes, activating PKA and phosphorylating hormone-sensitive lipase to trigger triglyceride breakdown and release of free fatty acids into circulation.
Free fatty acids are taken up by the liver, activating PPARα and increasing CPT1a expression to drive mitochondrial fatty acid oxidation and HMGCS2-mediated ketone body production.
Hepatic glucagon receptor activation and ketogenesis stimulate transcription and secretion of fibroblast growth factor 21 (FGF21) from hepatocytes.
Circulating FGF21 binds to receptors on brown adipose tissue, inducing expression of UCP1 and other thermogenic genes to uncouple mitochondrial respiration and generate heat.
UCP1-mediated uncoupling in brown adipose tissue increases energy expenditure, leading to sustained reduction in fat mass over one week.
Less supported by current evidence, but not ruled out
The fatty acids released from fat tissue attract special immune cells that release signals telling white fat cells to behave more like heat-burning brown fat, adding to the overall energy burn.
Free fatty acids released from white adipose tissue act as chemoattractants for eosinophils and type 2 innate lymphoid cells.
Infiltrating eosinophils and innate lymphoid cells secrete interleukin-4 and interleukin-13, which polarize macrophages to an M2 phenotype.
M2 macrophages secrete factors that induce UCP1 expression in white adipocytes, promoting their conversion to beige adipocytes.
Beige adipocytes contribute to increased energy expenditure alongside activated brown adipose tissue.
Fat tissue releases a hormone called adiponectin that tells the liver to burn more fat and make less new fat, helping clear excess lipids and support energy use.
G49 stimulates secretion of adiponectin from white adipose tissue.
Adiponectin binds to receptors on hepatocytes, activating AMPK and PPARα signaling pathways.
PPARα activation increases expression of fatty acid oxidation genes (e.g., CPT1a), enhancing hepatic lipid clearance.
Improved hepatic lipid metabolism supports sustained FGF21 production and reduces ectopic lipid accumulation.
Evidence from Studies
Supporting (1)
Community contributions welcome
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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