Mitochondria-Division Inhibitor 1 Protects Against Amyloid-β induced Mitochondrial Fragmentation and Synaptic Damage in Alzheimer’s Disease

Article type: Research Article

Authors: Reddy, P. Hemachandra^{a; b; c; d; e; f; g; *} | Manczak, Maria^a | Yin, XiangLing^a

Affiliations: [a] Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, TX, USA | [b] Garrison Institute on Aging, South West Campus, Texas Tech University Health Sciences Center, Lubbock, TX, USA | [c] Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, USA | [d] Deparment of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX, USA | [e] Department of Neurology, Texas Tech University Health Sciences Center, Lubbock, TX, USA | [f] Department of Speech, Language and Hearing Sciences, Texas Tech University Health Sciences Center, Lubbock, TX, USA | [g] Department of Public Health, Graduate School of Biomedical Sciences, Lubbock, TX, USA

Correspondence: [*] Correspondence to: P. Hemachandra Reddy, PhD, Executive Director and Chief Scientific Officer, Mildred and Shirley L. Garrison Chair in Aging, Professor of Cell Biology and Biochemistry, Neuroscience & Pharmacology and Neurology Departments, Texas Tech University Health Sciences Center, 3601 Fourth Street / MS / 9424 / 4A 124, Lubbock, TX 79430, USA. E-mail: hemachandra.reddy@ttuhsc.edu.

Abstract: The purpose our study was to determine the protective effects of mitochondria division inhibitor 1 (Mdivi1) in Alzheimer’s disease (AD). Mdivi1 is hypothesized to reduce excessive fragmentation of mitochondria and mitochondrial dysfunction in AD neurons. Very little is known about whether Mdivi1 can confer protective effects in AD. In the present study, we sought to determine the protective effects of Mdivi1 against amyloid-β (Aβ)- and mitochondrial fission protein, dynamin-related protein 1 (Drp1)-induced excessive fragmentation of mitochondria in AD progression. We also studied preventive (Mdivi1+Aβ42) and intervention (Aβ42+Mdivi1) effects against Aβ42 in N2a cells. Using real-time RT-PCR and immunoblotting analysis, we measured mRNA and protein levels of mitochondrial dynamics, mitochondrial biogenesis, and synaptic genes. We also assessed mitochondrial function by measuring H2O2, lipid peroxidation, cytochrome oxidase activity, and mitochondrial ATP. MTT assays were used to assess the cell viability. Aβ42 was found to impair mitochondrial dynamics, lower mitochondrial biogenesis, lower synaptic activity, and lower mitochondrial function. On the contrary, Mdivi1 enhanced mitochondrial fusion activity, lowered fission machinery, and increased biogenesis and synaptic proteins. Mitochondrial function and cell viability were elevated in Mdivi1-treated cells. Interestingly, Mdivi1 pre- and post-treated cells treated with Aβ showed reduced mitochondrial dysfunction, and maintained cell viability, mitochondrial dynamics, mitochondrial biogenesis, and synaptic activity. The protective effects of Mdivi1 were stronger in N2a+Aβ42 pre-treated with Mdivi1, than in N2a+Aβ42 cells than Mdivi1 post-treated cells, indicating that Mdivi1 works better in prevention than treatment in AD like neurons.

Keywords: Amyloid-β, dynamin-related protein 1, mitochondrial division inhibitor 1, mitochondrial dynamics, mitochondrial dysfunction, mitochondrial fission, synaptic pathology

DOI: 10.3233/JAD-170051

Journal: Journal of Alzheimer's Disease, vol. 58, no. 1, pp. 147-162, 2017