Function and Change with Aging of α-Klotho in the Kidney.

The α-Klotho mouse is an animal model that prematurely shows phenotypes resembling human aging, such as osteoporosis, arteriosclerosis, pulmonary emphysema, and kidney damage. Interestingly, these abnormalities are triggered by a deficiency of a single protein, α-Klotho. The kidney is an organ that highly expresses α-Klotho, suggesting that α-Klotho is important for kidney function. Recent studies suggest that α-Klotho is associated with phosphate, vitamin D, and calcium homeostasis. The calcium imbalance in α-Klotho mice may induce calpain overactivation, leading to cell death and tissue destruction. α-Klotho is predicted to have glycosidase activity, capable of modifying the N-glycans of channels and transporters and regulating transmembrane movement of several ions, including calcium. Interestingly, N-glycan changes are observed in the kidney of α-Klotho mice and normal aged mice in association with decreased α-Klotho levels. These results imply that glycobiology and α-Klotho function are interesting targets for future studies.