FGF-21

Fibroblast growth factor 21 (FGF21) is a member of the fibroblast growth factor (FGF) 19 subfamily, primarily produced in the liver and adipose tissue, and plays a significant role in regulating energy metabolism. Researchers primarily study FGF21 for its involvement in metabolic processes, including glucose and lipid metabolism, as well as its potential implications in various diseases such as obesity, type 2 diabetes, and nonalcoholic fatty liver disease (NAFLD). Key findings indicate that elevated levels of FGF21 are associated with metabolic dysfunction, while its administration can influence autophagy and reduce apoptosis in chondrocytes, suggesting a protective role in conditions like osteoarthritis. Current research status highlights FGF21 as a promising target for biopharmaceutical therapies aimed at addressing metabolic disorders, although concerns regarding safety and effects on bone homeostasis warrant further investigation.

Fibroblast Growth Factor 21 (FGF21) is an endogenous hormone primarily produced in the liver and adipose tissue, belonging to the FGF19 subfamily of growth factors. It is a protein that plays a significant role in inter-organ communication and is involved in various physiological processes, including metabolism, reproduction, and immunity. Researchers have found that FGF21 is expressed not only in hepatic tissues but also in adipose tissue, thymus, heart, pancreas, and skeletal muscle in mice. Elevated levels of FGF21 have been associated with conditions such as obesity, type 2 diabetes, preeclampsia, and cancer. FGF21 has been extensively studied for its role in regulating glucose and lipid metabolism. It is known to protect against diseases by mediating autophagy and has been investigated for its potential therapeutic effects in osteoarthritis, nonalcoholic fatty liver disease (NAFLD), and atherosclerosis. The mechanism of action of FGF21 involves binding to the β-Klotho co-receptor and FGF receptors, primarily in hepatic and adipose tissues, which triggers downstream signaling pathways affecting fat and glucose metabolism. Researchers have observed that FGF21 influences pathways such as the SIRT1-mTOR signaling pathway, which is crucial in autophagy and cellular senescence. Pharmacokinetic properties of FGF21, including its half-life and bioavailability, are not well-documented in the literature, indicating a need for further research. Clinically, FGF21-based therapies are being explored for their potential in treating metabolic dysfunction-associated steatotic liver disease and other metabolic disorders. However, the safety and efficacy of these therapies are still under investigation, with concerns about injection site reactions and effects on bone homeostasis requiring careful evaluation. Regulatory standing varies by region, with ongoing research and clinical trials shaping its future therapeutic applications.

FGF21 acts primarily through the β-Klotho co-receptor and FGF receptors, particularly in hepatic and adipose tissues. This interaction activates signaling pathways such as the SIRT1-mTOR pathway, leading to effects on glucose and lipid metabolism, autophagy, and cellular senescence.

Fibroblast growth factor 21 (FGF21) primarily exerts its effects through binding to the FGF receptor (FGFR) in the presence of the co-receptor β-Klotho, activating downstream signaling pathways such as the SIRT1-mTOR pathway, which mediates autophagy and influences energy metabolism. This signaling cascade is implicated in various biological processes, including glucose and lipid metabolism, apoptosis, and extracellular matrix degradation, although the complete mechanisms underlying FGF21's diverse roles, particularly in bone homeostasis and its interaction with other pathways like microRNA-33 regulation, remain incompletely understood.

Current evidence is limited regarding the long-term effects of FGF21-based therapies on bone homeostasis, particularly in diverse populations and those with pre-existing bone conditions. Further research is needed to clarify the mechanisms by which FGF21 influences bone metabolism and to resolve contradictory findings regarding its potential adverse effects on bone health. Additionally, larger randomized controlled trials (RCTs) are necessary to assess the safety and efficacy of FGF21 agonists in treating metabolic disorders, including nonalcoholic fatty liver disease (NAFLD) and osteoarthritis, while considering the impact on other physiological systems.