In vitro study of interaction of 17β-hydroxysteroid dehydrogenase type 10 and cyclophilin D and its potential implications for Alzheimer’s disease

In early stages of Alzheimer’s disease (AD), amyloid-β (Aβ) accumulates in neuronal mitochondria where it interacts with a number of biomolecules including 17beta-hydroxysteroide dehydrogenase 10 (17β-HSD10) and cyclophilin D (cypD). It has been hypothesized that 17β-HSD10 interacts with cypD preventing it from opening mitochondrial permeability transition pores and that its regulation during AD may be affected by the accumulation of Aβ. In this work, we demonstrate for the first time that 17β-HSD10 and cypD form a stable complex in vitro. Furthermore, we show that factors, such as pH, ionic environment and the presence of Aβ, affect the ability of 17β-HSD10 to bind cypD. We demonstrate that K(+) and Mg(2+) ions present at low levels may facilitate this binding. We also show that different fragments of Aβ (Aβ(1–40) and Aβ(1–42)) affect the interaction between 17β-HSD10 and cypD differently and that Aβ(1–42) (in contrast to Aβ(1–40)) is capable of simultaneously binding both 17β-HSD10 and cypD in a tri-complex.