Identification of the enzymatic cleavage relationship between anti-aging protein α-Klotho and Alzheimer's disease biomarker BACE1

Background The alpha-Klotho is known to be involved in longevity and various age-related diseases, including cognitive impairment. BACE1, an important enzyme associated with the pathological process of Alzheimer's disease (AD), serves as a biomarker for predicting changes in cognitive function. Although both proteins are closely linked to age-related cognitive function, the mechanism of their interaction remains unclear. Objective To identify the enzymatic digestion relation between alpha-Klotho and BACE1 and the specific cleavage site. Methods Thirty elderly and forty-five young individuals were recruited. The cleavage product was identified by Coomassie blue staining, western blot, and MALDI-TOF mass spectrometry. The concentrations of plasma proteins were measured by ELISA. Results A new protein product was identified after the digestion reaction. BACE1 cleaved the alpha-Klotho peptide 951-981 at the F-T residues. When the F-T residues were replaced with K-K, BACE1 was unable to cleave the mutant peptide. The plasma levels of alpha-Klotho were significantly lower in elderly participants than in young participants (p < 0.0001). However, there was no significant difference in plasma BACE1 levels between elderly and young participants (p = 0.164). In elderly adults, there was a significant positive correlation between plasma BACE1 and alpha-Klotho protein levels (p = 0.009, r = 0.469), while this correlation was not observed in young adults (p = 0.170, r = -0.208). Conclusions The anti-aging protein alpha-Klotho is a substrate of BACE1 with a specific cleavage site at F-T. The BACE1/alpha-Klotho pathway may serve as a common axis for age-related cognitive decline.