ATP6AP2 variant impairs CNS development and neuronal survival to cause fulminant neurodegeneration
Takuo Hirose, … , Genevieve Nguyen, Matthias Groszer
Takuo Hirose, … , Genevieve Nguyen, Matthias Groszer
Published April 15, 2019
Citation Information: J Clin Invest. 2019;129(5):2145-2162. https://doi.org/10.1172/JCI79990.
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Research Article Genetics Neuroscience

ATP6AP2 variant impairs CNS development and neuronal survival to cause fulminant neurodegeneration

Abstract

Vacuolar H+-ATPase–dependent (V-ATPase–dependent) functions are critical for neural proteostasis and are involved in neurodegeneration and brain tumorigenesis. We identified a patient with fulminant neurodegeneration of the developing brain carrying a de novo splice site variant in ATP6AP2 encoding an accessory protein of the V-ATPase. Functional studies of induced pluripotent stem cell–derived (iPSC-derived) neurons from this patient revealed reduced spontaneous activity and severe deficiency in lysosomal acidification and protein degradation leading to neuronal cell death. These deficiencies could be rescued by expression of full-length ATP6AP2. Conditional deletion of Atp6ap2 in developing mouse brain impaired V-ATPase–dependent functions, causing impaired neural stem cell self-renewal, premature neuronal differentiation, and apoptosis resulting in degeneration of nearly the entire cortex. In vitro studies revealed that ATP6AP2 deficiency decreases V-ATPase membrane assembly and increases endosomal-lysosomal fusion. We conclude that ATP6AP2 is a key mediator of V-ATPase–dependent signaling and protein degradation in the developing human central nervous system.

Authors

Takuo Hirose, Alfredo Cabrera-Socorro, David Chitayat, Thomas Lemonnier, Olivier Féraud, Carmen Cifuentes-Diaz, Nicolas Gervasi, Cedric Mombereau, Tanay Ghosh, Loredana Stoica, Jeanne d’Arc Al Bacha, Hiroshi Yamada, Marcel A. Lauterbach, Marc Guillon, Kiriko Kaneko, Joy W. Norris, Komudi Siriwardena, Susan Blasér, Jérémie Teillon, Roberto Mendoza-Londono, Marion Russeau, Julien Hadoux, Sadayoshi Ito, Pierre Corvol, Maria G. Matheus, Kenton R. Holden, Kohji Takei, Valentina Emiliani, Annelise Bennaceur-Griscelli, Charles E. Schwartz, Genevieve Nguyen, Matthias Groszer

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Figure 9

Enhanced vesicular fusion and reduction of membrane-associated V-ATPase holoenzyme in HeLa cells following ATP6AP2 knockdown.

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Enhanced vesicular fusion and reduction of membrane-associated V-ATPase ...
(A) Endosome-lysosome fusion studied by time-lapse microscopy. Representative images of increased fusion and perinuclear clustering following ATP6AP2 knockdown are obtained from merged single frames of Supplemental Videos 1–4. Dashed lines: nucleus. (B) The number of yellow vesicles resulting from the fusion of lysosomes labeled with LysoTracker (Red) and endosomes labeled with Oregon green 488. Data show individual values and mean ± SEM; n = 6–7 from 3 independent experiments. *P < 0.05, **P < 0.01, 1-way ANOVA followed by Bonferroni’s post test. (C) Membrane-bound V1B2 subunit of the V1 sector and V0a1 subunit of the V0 sector of the V-ATPase of transfected HeLa cells were analyzed by Western blot (left). The band intensity was quantified (right) as a ratio of V1B2 to V0a1. Data show individual values and mean ± SEM; n = 5–7 from 3 independent experiments. **P < 0.01, ***P < 0.001; NS, P > 0.05; 1-way ANOVA followed by Bonferroni’s post test.