Klotho-Fibroblast Growth Factor Receptor complex (Klotho-FGFR complex) (Klotho-FGFR complex)

The Klotho-Fibroblast Growth Factor Receptor (FGFR) complex is a specialized heteromeric signaling unit essential for maintaining systemic mineral homeostasis. It is primarily composed of the transmembrane or soluble protein alpha-Klotho, which acts as an obligatory co-receptor, and specific isoforms of the fibroblast growth factor receptor, most notably FGFR1c, FGFR3c, and FGFR4 (PMID: 29343898). This complex facilitates the high-affinity binding of the bone-derived hormone Fibroblast Growth Factor 23 (FGF23), which is otherwise unable to activate FGFRs effectively on its own. In the kidney, activation of the Klotho-FGFR complex triggers intracellular signaling pathways that downregulate phosphate transporters in the proximal tubule and suppress the expression of CYP27B1, the enzyme responsible for producing active vitamin D (PMID: 30115748). Clinically, the Klotho-FGFR complex is a central target in the management of chronic kidney disease (CKD) and metabolic bone disorders. In CKD, a progressive decline in Klotho expression leads to FGF23 resistance, resulting in hyperphosphatemia and accelerated cardiovascular aging. Conversely, excessive FGF23 activity or complex overstimulation leads to phosphate-wasting diseases such as X-linked hypophosphatemia, which is treated with the monoclonal antibody Burosumab to block FGF23 interaction with the complex (FDA, 2018). Current therapeutic research also focuses on Klotho mimetics and recombinant Klotho protein to restore mineral balance and provide cardioprotective effects in patients with renal failure.

Other names

alpha-Klotho-FGFR complexFGF23-Klotho-FGFR ternary complexKlotho-FGFR1c complexKlotho-FGFR3c complexKlotho-FGFR4 complex

Modulation of Fibroblast Growth Factor 23 (FGF23) signaling through the Klotho-FGFR ternary complex to regulate renal phosphate reabsorption and 1,25-dihydroxyvitamin D synthesis.