β-amyloid(25-35) inhibits the activity of inositol (1,4,5)-trisphosphate-5-phosphatase

Abstract

β-amyloid (Aβ) peptides are known to disrupt calcium homeostasis in cells. In the present study, the effects of A β(25-35) upon the activity of soluble Ins(1, 4, 5)P₃-5-phos-phatase have been investigated. Aβ(25-35) inhibited, and dithiothreitol (DTT) increased the activity of soluble rat cerebellar Ins(1, 4, 5)P₃-5-phosphatase. The change in activity was not accompanied by an obvious change in the sensitivity of the Ins (1, 4, 5) P₃-5-phosphatase to inhibition by glucoses-phosphate or phytic acid. Aβ(35-25) also inhibited soluble Ins(1, 4, 5)P₃-5-phosphatase activity, but at a lower potency than Aβ(25-35). It is concluded that Aβ(25-35) affects the metabolism of Ins (1, 4, 5) P₃ although the potency is not sufficiently high to contribute to any significant extent to the effects of this peptide upon calcium homeostasis.

Key Words:

• β-amyloid
• Ins(1, 4, 5) P₃-5-phosphatase
• calcium homeostasis