In early stages of Alzheimer's disease (AD), amyloid beta (Aβ) accumulates in the mitochondrial matrix and interacts with mitochondrial proteins, such as cyclophilin D (cypD) and 17β-hydroxysteroid dehydrogenase 10 (17β-HSD10). Multiple processes associated with AD such as increased production or oligomerization of Aβ affect these interactions and disbalance the equilibrium between the biomolecules, which contributes to mitochondrial dysfunction. Here, we investigate the effect of the ionic environment on the interactions of Aβ (Aβ1-40, Aβ1-42) with cypD and 17β-HSD10 using a surface plasmon resonance (SPR) biosensor. We show that changes in concentrations of K+ and Mg2+ significantly affect the interactions and may increase the binding efficiency between the biomolecules by up to 35% and 65% for the interactions with Aβ1-40 and Aβ1-42, respectively, in comparison with the physiological state. We also demonstrate that while the binding of Aβ1-40 to cypD and 17β-HSD10 takes place preferentially around the physiological concentrations of ions, decreased concentrations of K+ and increased concentrations of Mg2+ promote the interaction of both mitochondrial proteins with Aβ1-42. These results suggest that the ionic environment represents an important factor that should be considered in the investigation of biomolecular interactions taking place in the mitochondrial matrix under physiological as well as AD-associated conditions.

• Klíčová slova
• 17β-hydroxysteroid dehydrogenase 10 (17β-HSD10), amyloid beta (Aβ), biomolecular interactions, cyclophilin D (cypD), ionic environment, mitochondrial matrix, surface plasmon resonance (SPR),
• MeSH
• 17-hydroxysteroidní dehydrogenasy chemie   genetika   MeSH
• Alzheimerova nemoc diagnóza   genetika   patologie   MeSH
• amyloidní beta-protein chemie   MeSH
• biosenzitivní techniky metody   MeSH
• ionty chemie   MeSH
• lidé MeSH
• mitochondriální proteiny chemie   MeSH
• mitochondrie chemie   MeSH
• peptidové fragmenty chemie   genetika   MeSH
• peptidylprolylisomerasa F chemie   genetika   MeSH
• povrchová plasmonová rezonance metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 17-hydroxysteroidní dehydrogenasy MeSH
• 3 (or 17)-beta-hydroxysteroid dehydrogenase MeSH Prohlížeč
• amyloidní beta-protein MeSH
• ionty MeSH
• mitochondriální proteiny MeSH
• peptidové fragmenty MeSH
• peptidylprolylisomerasa F MeSH

Progressive mitochondrial dysfunction due to the accumulation of amyloid beta (Aβ) peptide within the mitochondrial matrix represents one of the key characteristics of Alzheimer's disease (AD) and appears already in its early stages. Inside the mitochondria, Aβ interacts with a number of biomolecules, including cyclophilin D (cypD) and 17β-hydroxysteroid dehydrogenase type 10 (17β-HSD10), and affects their physiological functions. However, despite intensive ongoing research, the exact mechanisms through which Aβ impairs mitochondrial functions remain to be explained. In this work, we studied the interactions of Aβ with cypD and 17β-HSD10 in vitro using the surface plasmon resonance (SPR) method and determined the kinetic parameters (association and dissociation rates) of these interactions. This is the first work which determines all these parameters under the same conditions, thus, enabling direct comparison of relative affinities of Aβ to its mitochondrial binding partners. Moreover, we used the determined characteristics of the individual interactions to simulate the concurrent interactions of Aβ with cypD and 17β-HSD10 in different model situations associated with the progression of AD. This study not only advances the understanding of Aβ-induced processes in mitochondria during AD, but it also provides a new perspective on research into complex multi-interaction biomolecular processes in general.

• Klíčová slova
• 17β-hydroxysteroid dehydrogenase 10 (17β-HSD10), amyloid beta (Aβ), biomolecular interaction analysis, cyclophilin D (cypD), kinetic parameters, surface plasmon resonance (SPR),
• MeSH
• 17-hydroxysteroidní dehydrogenasy chemie   metabolismus   MeSH
• Alzheimerova nemoc metabolismus   MeSH
• amyloidní beta-protein chemie   metabolismus   MeSH
• biosenzitivní techniky MeSH
• lidé MeSH
• mitochondriální proteiny chemie   metabolismus   MeSH
• peptidylprolylisomerasa F chemie   metabolismus   MeSH
• povrchová plasmonová rezonance MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 17-hydroxysteroidní dehydrogenasy MeSH
• amyloidní beta-protein MeSH
• mitochondriální proteiny MeSH
• peptidylprolylisomerasa F MeSH

The nucleus-encoded 17β-hydroxysteroid dehydrogenase type 10 (17β-HSD10) regulates cyclophilin D (cypD) in the mitochondrial matrix. CypD regulates opening of mitochondrial permeability transition pores. Both mechanisms may be affected by amyloid β peptides accumulated in mitochondria in Alzheimer's disease (AD). In order to clarify changes occurring in brain mitochondria, we evaluated interactions of both mitochondrial proteins in vitro (by surface plasmon resonance biosensor) and detected levels of various complexes of 17β-HSD10 formed in vivo (by sandwich ELISA) in brain mitochondria isolated from the transgenic animal model of AD (homozygous McGill-R-Thy1-APP rats) and in cerebrospinal fluid samples of AD patients. By surface plasmon resonance biosensor, we observed the interaction of 17β-HSD10 and cypD in a direct real-time manner and determined, for the first time, the kinetic parameters of the interaction (ka 2.0 × 105 M1s-1, kd 5.8 × 104 s-1, and KD 3.5 × 10-10 M). In McGill-R-Thy1-APP rats compared to controls, levels of 17β-HSD10-cypD complexes were decreased and those of total amyloid β increased. Moreover, the levels of 17β-HSD10-cypD complexes were decreased in cerebrospinal fluid of individuals with AD (in mild cognitive impairment as well as dementia stages) or with Frontotemporal lobar degeneration (FTLD) compared to cognitively normal controls (the sensitivity of the complexes to AD dementia was 92.9%, that to FTLD 73.8%, the specificity to AD dementia equaled 91.7% in a comparison with the controls but only 26.2% with FTLD). Our results demonstrate the weakened ability of 17β-HSD10 to regulate cypD in the mitochondrial matrix probably via direct effects of amyloid β. Levels of 17β-HSD10-cypD complexes in cerebrospinal fluid seem to be the very sensitive indicator of mitochondrial dysfunction observed in neurodegeneration but unfortunately not specific to AD pathology. We do not recommend it as the new biomarker of AD.

• Klíčová slova
• Alzheimer's disease, Amyloid β, Cerebrospinal fluid, Frontotemporal lobar degeneration, Mitochondrial matrix proteins, Transgenic rat model,
• MeSH
• 17-hydroxysteroidní dehydrogenasy mozkomíšní mok   metabolismus   MeSH
• Alzheimerova nemoc metabolismus   MeSH
• amyloidový prekurzorový protein beta genetika   MeSH
• kinetika MeSH
• lidé MeSH
• mitochondrie metabolismus   MeSH
• mozek metabolismus   MeSH
• peptidylprolylisomerasa F metabolismus   MeSH
• potkani transgenní MeSH
• potkani Wistar MeSH
• povrchová plasmonová rezonance MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 17-hydroxysteroidní dehydrogenasy MeSH
• amyloidový prekurzorový protein beta MeSH
• peptidylprolylisomerasa F MeSH