Arterial klotho expression and FGF23 effects on vascular calcification and function.

Area of Science:

• Cardiovascular Biology
• Endocrinology
• Molecular Biology

Background:

• Recent studies suggest fibroblast growth factor 23 (FGF23) and Klotho play roles in cardiovascular disease.
• However, the specific mechanisms of FGF23-Klotho signaling in the vasculature remain unclear.

Purpose of the Study:

• To investigate the expression of Klotho in mouse arteries.
• To determine the functional impact of FGF23 on vascular tissues.
• To generate and analyze a mouse model with vascular smooth muscle cell-specific Klotho deletion.

Main Methods:

• Quantitative real-time PCR and Western blotting to assess Klotho expression in mouse arteries.
• Generation of Sm22-KL(-/-) mice with vascular smooth muscle cell-specific Klotho deletion.
• Assessment of FGF23 signaling via Egr-1 expression in renal and arterial tissues.
• In vitro studies using bovine vascular smooth muscle cells (bVSMCs) to evaluate FGF23's effect on calcification.
• Ex vivo analysis of murine arterial function following FGF23 treatment.

Main Results:

• Arterial Klotho expression was very low; protein levels were undetectable.
• No differences in arterial Klotho or serum mineral metabolism markers were found between Sm22-KL(-/-) and wild-type mice.
• FGF23 increased renal Egr-1 expression but not arterial Egr-1, indicating absent FGF23 signaling in arteries.
• FGF23 did not affect vascular calcification in bVSMCs or ex vivo arterial function in mice.

Conclusions:

• FGF23-Klotho signaling is absent in mouse arteries.
• FGF23 treatment did not impact vascular calcification or function in the studied models.
• Current data do not support Klotho-mediated FGF23 effects in the vasculature, though human studies are needed.