BACKGROUND: The mitochondrial enzyme 17β-hydroxysteroid dehydrogenase type 10 (HSD10) is implicated in neurodegenerative disorders, particularly Alzheimer’s disease (AD), through its interplay with the amyloid-β peptide (Aβ). However, its independent pathological role in AD remains unclear. METHODS: To explore the individual effects of HSD10 and amyloid precursor protein (APP) overexpression (including the Aβ42-generating APPSwe/Ind variant), monoclonal HEK293 cell lines were developed. Cellular fitness was evaluated by measuring ATP levels, cell viability, and cytotoxicity measurements under glucose and galactose culture conditions. Mitochondrial metabolic changes were analysed using mitochondrial electron flow measurements in response to various metabolic substrates. HSD10 enzymatic activity was monitored using a fluorogenic probe, and two HSD10 inhibitors were tested for their ability to reduce cytotoxic effects. Statistical significance was determined using appropriate tests as detailed in the methods section. RESULTS: The overexpression of HSD10 or APPSwe/Ind led to mitochondrial dysfunction and reduced viability, particularly under glucose-deprived conditions. HSD10-driven cytotoxicity was linked to its enzymatic activity and associated with impaired TCA cycle function, reduced β-oxidation, and increased oxidative stress. In contrast, APPSwe/Ind overexpression induced Aβ42 production, glucose hypermetabolism, and enhanced β-oxidation. Aβ42 also affected HSD10 activity and further amplified its cytotoxic effects. The benzothiazole-based HSD10 inhibitor 34 restored cell viability under both HSD10 overexpression and Aβ42-rich conditions. CONCLUSIONS: HSD10 and Aβ42 each contribute to mitochondrial impairment via distinct metabolic pathways. These findings established HSD10 as an independent pathological factor in AD and support the potential of HSD10 inhibitors, particularly inhibitor 34, as therapeutic agents targeting mitochondrial dysfunction in AD. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13195-025-01821-8.

• Keywords
• 17β-hydroxysteroid dehydrogenase type 10, Alzheimer’s disease, Amyloid precursor protein, Amyloid-β peptide, Mitochondria,
• Publication type
• Journal Article MeSH

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.

• Keywords
• 17β-hydroxysteroid dehydrogenase 10 (17β-HSD10), amyloid beta (Aβ), biomolecular interactions, cyclophilin D (cypD), ionic environment, mitochondrial matrix, surface plasmon resonance (SPR),
• MeSH
• 17-Hydroxysteroid Dehydrogenases chemistry   genetics   MeSH
• Alzheimer Disease diagnosis   genetics   pathology   MeSH
• Amyloid beta-Peptides chemistry   MeSH
• Biosensing Techniques methods   MeSH
• Ions chemistry   MeSH
• Humans MeSH
• Mitochondrial Proteins chemistry   MeSH
• Mitochondria chemistry   MeSH
• Peptide Fragments chemistry   genetics   MeSH
• Peptidyl-Prolyl Isomerase F chemistry   genetics   MeSH
• Surface Plasmon Resonance methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• 17-Hydroxysteroid Dehydrogenases MeSH
• 3 (or 17)-beta-hydroxysteroid dehydrogenase MeSH Browser
• Amyloid beta-Peptides MeSH
• Ions MeSH
• Mitochondrial Proteins MeSH
• Peptide Fragments MeSH
• Peptidyl-Prolyl Isomerase F MeSH