Calcium Signaling and Mitochondrial Function in Presenilin 2 Knock-Out Mice: Looking for Any Loss-of-Function Phenotype Related to Alzheimer's Disease

• Published in: Cells (Basel, Switzerland) Vol. 10; no. 2; p. 204
• Main Authors: Rossi, Alice, Galla, Luisa, Gomiero, Chiara, Zentilin, Lorena, Giacca, Mauro, Giorgio, Valentina, Calì, Tito, Pozzan, Tullio, Greotti, Elisa, Pizzo, Paola
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 21-01-2021; MDPI
• Subjects: Adenosine Triphosphate - biosynthesis; Age; Alzheimer Disease - metabolism; Alzheimer Disease - pathology; Alzheimer's disease; Amyloid precursor protein; Animal models; Animals; Apposition; bioenergetics; Ca2+ signaling; Calcium (mitochondrial); Calcium influx; Calcium Signaling; Calcium signalling; Cameras; Cell Respiration; Citric Acid Cycle; Cognitive ability; Cytosol - metabolism; Dementia; Endoplasmic reticulum; Endoplasmic Reticulum - metabolism; Experiments; Genetic engineering; Genomes; Genotype & phenotype; Glycolysis; Hypotheses; Membrane potential; Membrane Potential, Mitochondrial; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitochondria; Mitochondria - metabolism; Mutation; Neurodegenerative diseases; Neurons; Neurons - metabolism; Neurotoxicity; Oxidative Phosphorylation; Pathogenesis; Peptides; Phenotype; Phenotypes; Presenilin 1; Presenilin 2; Presenilin-2 - deficiency; Presenilin-2 - metabolism; PS2; Secretase; Senile plaques; Software; United States > US; Italy; Germany; neuronal hyperexcitability; Ca2+ signaling; bioenergetics; mitochondria; oxygen consumption rate; mitochondrial membrane potential; presenilin 2; Alzheimer′s disease; PS2
• ISSN: 2073-4409; 2073-4409
• DOI: 10.3390/cells10020204

Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder in which learning, memory and cognitive functions decline progressively. Familial forms of AD (FAD) are caused by mutations in amyloid precursor protein (
), presenilin 1 (
) and presenilin 2 (
) genes. Presenilin 1 (PS1) and its homologue, presenilin 2 (PS2), represent, alternatively, the catalytic core of the γ-secretase complex that, by cleaving APP, produces neurotoxic amyloid beta (Aβ) peptides responsible for one of the histopathological hallmarks in AD brains, the amyloid plaques. Recently,
FAD mutations have been associated with a loss-of-function phenotype. To investigate whether this finding can also be extended to
FAD mutations, we studied two processes known to be modulated by PS2 and altered by FAD mutations: Ca
signaling and mitochondrial function. By exploiting neurons derived from a
knock-out (PS2-/-) mouse model, we found that, upon IP
-generating stimulation, cytosolic Ca
handling is not altered, compared to wild-type cells, while mitochondrial Ca
uptake is strongly compromised. Accordingly, PS2-/- neurons show a marked reduction in endoplasmic reticulum-mitochondria apposition and a slight alteration in mitochondrial respiration, whereas mitochondrial membrane potential, and organelle morphology and number appear unchanged. Thus, although some alterations in mitochondrial function appear to be shared between PS2-/- and FAD-PS2-expressing neurons, the mechanisms leading to these defects are quite distinct between the two models. Taken together, our data appear to be difficult to reconcile with the proposal that FAD-PS2 mutants are loss-of-function, whereas the concept that PS2 plays a key role in sustaining mitochondrial function is here confirmed.