NADH Fluorescence Lifetime Imaging Microscopy Reveals Selective Mitochondrial Dysfunction in Neurons Overexpressing Alzheimer's Disease-Related Proteins

Moritz A Niederschweiberer; Patrick M Schaefer; Larry N Singh; Ludwig Lausser; Devyani Bhosale; Raphael Hesse; Enrico Calzia; Hans A Kestler; Angelika Rueck; Douglas C Wallace; Bjoern von Einem; Christine A F von Arnim

doi:10.3389/fmolb.2021.671274

NADH Fluorescence Lifetime Imaging Microscopy Reveals Selective Mitochondrial Dysfunction in Neurons Overexpressing Alzheimer's Disease-Related Proteins

Front Mol Biosci. 2021 Jun 14:8:671274. doi: 10.3389/fmolb.2021.671274. eCollection 2021.

Authors

Moritz A Niederschweiberer^{1

2}, Patrick M Schaefer^{1

3}, Larry N Singh³, Ludwig Lausser⁴, Devyani Bhosale⁵, Raphael Hesse¹, Enrico Calzia⁶, Hans A Kestler⁴, Angelika Rueck⁷, Douglas C Wallace^{3

8}, Bjoern von Einem¹, Christine A F von Arnim^{1

9}

Affiliations

¹ Department of Neurology, Ulm University, Ulm, Germany.
² Department of Neurology and Experimental Neurology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.
³ Center for Mitochondrial and Epigenomic Medicine, Children's Hospital of Philadelphia Research Institute, University of Pennsylvania, Philadelphia, PA, United States.
⁴ Institute of Medical Systems Biology, Ulm University, Ulm, Germany.
⁵ Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, United States.
⁶ University Medical School, Institute of Anesthesiological Pathophysiology and Process Engineering, Ulm, Germany.
⁷ Core Facility Confocal and Multiphoton Microscopy, Ulm University, Ulm, Germany.
⁸ Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, United States.
⁹ Division of Geriatrics, University Medical Center Göttingen, Göttingen, Germany.

Abstract

Alzheimer's disease (AD), the most prevalent form of dementia, affects globally more than 30 million people suffering from cognitive deficits and neuropsychiatric symptoms. Substantial evidence for the involvement of mitochondrial dysfunction in the development and/or progression of AD has been shown in addition to the pathological hallmarks amyloid beta (Aβ) and tau. Still, the selective vulnerability and associated selective mitochondrial dysfunction cannot even be resolved to date. We aimed at optically quantifying mitochondrial function on a single-cell level in primary hippocampal neuron models of AD, unraveling differential involvement of cell and mitochondrial populations in amyloid precursor protein (APP)-associated mitochondrial dysfunction. NADH lifetime imaging is a highly sensitive marker-free method with high spatial resolution. However, deciphering cellular bioenergetics of complex cells like primary neurons has still not succeeded yet. To achieve this, we combined highly sensitive NADH lifetime imaging with respiratory inhibitor treatment, allowing characterization of mitochondrial function down to even the subcellular level in primary neurons. Measuring NADH lifetime of the same neuron before and after respiratory treatment reveals the metabolic delta, which can be taken as a surrogate for cellular redox capacity. Correlating NADH lifetime delta with overexpression strength of Aβ-related proteins on the single-cell level, we could verify the important role of intracellular Aβ-mediated mitochondrial toxicity. Subcellularly, we could demonstrate a higher respiration in neuronal somata in general than dendrites, but a similar impairment of somatic and dendritic mitochondria in our AD models. This illustrates the power of NADH lifetime imaging in revealing mitochondrial function on a single and even subcellular level and its potential to shed light into bioenergetic alterations in neuropsychiatric diseases and beyond.

Keywords: Alzheimer’s disease; NADH; amyloid beta; energy metabolism; mitochondria; redox imaging.