Fibroblast growth factor 23

Fibroblast growth factor 23 (FGF23) is a member of the fibroblast growth factor family, which is involved in the regulation of phosphate homeostasis and vitamin D metabolism. FGF23 is primarily secreted by osteocytes and osteoblasts in the bone.

Function

FGF23 plays a crucial role in maintaining phosphate balance in the body. It acts on the kidneys to reduce the reabsorption of phosphate, leading to increased excretion of phosphate in the urine. Additionally, FGF23 suppresses the synthesis of 1,25-dihydroxyvitamin D, the active form of vitamin D, which in turn decreases intestinal absorption of phosphate.

Clinical significance

Abnormal levels of FGF23 are associated with several disorders. Elevated levels of FGF23 can lead to hypophosphatemia, a condition characterized by low levels of phosphate in the blood. This is seen in disorders such as tumor-induced osteomalacia and X-linked hypophosphatemic rickets. Conversely, low levels of FGF23 can result in hyperphosphatemia, which is often observed in patients with chronic kidney disease.

Genetic information

The FGF23 gene is located on chromosome 12 in humans. Mutations in this gene can lead to various phosphate-wasting disorders. For example, mutations causing increased activity of FGF23 are responsible for autosomal dominant hypophosphatemic rickets.

Interactions

FGF23 interacts with klotho, a co-receptor that enhances its activity. The FGF23-klotho complex binds to fibroblast growth factor receptors (FGFRs) on target cells, initiating a signaling cascade that results in the regulation of phosphate and vitamin D metabolism.

See also

• Fibroblast growth factor receptor
• Phosphate homeostasis
• Vitamin D metabolism

External links

• FGF23 gene information at NCBI
• FGF23 protein information at UniProt