Muscle plasticity is influenced by renal function and caloric intake through the FGF23-vitamin D axis

Area of Science:

• Endocrinology
• Nephrology
• Muscle Physiology

Background:

• Skeletal muscle plasticity is crucial for vertebrate metabolism.
• Renal dysfunction and obesity are prevalent conditions linked to skeletal muscle alterations.
• The interplay between kidney, bone, and muscle health significantly impacts patient quality of life.

Purpose of the Study:

• To review the influence of the kidney-bone-muscle axis on skeletal muscle plasticity.
• To elucidate the role of vitamin D and FGF23 in this axis.
• To connect renal dysfunction and obesity to muscle anabolism via this axis.

Main Methods:

• Literature review of existing studies.
• Analysis of the non-traditional kidney-bone-muscle axis.
• Examination of hormonal regulation involving vitamin D and FGF23.

Main Results:

• Renal disease reduces active vitamin D (1,25(OH)2-vitamin D) due to decreased renal mass and phosphate retention.
• Phosphate retention stimulates FGF23, which further inhibits vitamin D synthesis.
• Obesity increases FGF23 and decreases vitamin D, while caloric restriction has the opposite effect.

Conclusions:

• Phosphate retention and caloric intake modulate 1,25(OH)2-vitamin D levels.
• 1,25(OH)2-vitamin D plays a key role in skeletal muscle anabolism.
• Understanding this axis is vital for managing patients with renal dysfunction and obesity.