ATP6V0A1 encoding the a1-subunit of the V0 domain of vacuolar H+-ATPases is essential for brain development in humans and mice

Kazushi Aoto,Jun Tohyama,Takehiro Miyazaki,Yasuhiko Ago,Takeshi Mizuguchi,Orna Epstein,Atsuo Fukuda,Noriyuki Akasaka,Noriko Miyake,Atsushi Takata,Hiroki Mutoh,Mitsuko Nakashima,Kyoko Hoshino,Satoko Miyatake,Ryuta Tanaka,Hazrat Belal,Tenpei Akita,Revital Ben-Haim,Eli Heyman,Naomichi Matsumoto,Yasuo Nomura ,Shuji Takabayashi,Mitsuhiro Kato,Chihiro Ohba,Hirotomo Saitsu

doi:10.1038/s41467-021-22389-5

Abstract

Vacuolar H+-ATPases (V-ATPases) transport protons across cellular membranes to acidify various organelles. ATP6V0A1 encodes the a1-subunit of the V0 domain of V-ATPases, which is strongly expressed in neurons. However, its role in brain development is unknown. Here we report four individuals with developmental and epileptic encephalopathy with ATP6V0A1 variants: two individuals with a de novo missense variant (R741Q) and the other two individuals with biallelic variants comprising one almost complete loss-of-function variant and one missense variant (A512P and N534D). Lysosomal acidification is significantly impaired in cell lines expressing three missense ATP6V0A1 mutants. Homozygous mutant mice harboring human R741Q (Atp6v0a1R741Q) and A512P (Atp6v0a1A512P) variants show embryonic lethality and early postnatal mortality, respectively, suggesting that R741Q affects V-ATPase function more severely. Lysosomal dysfunction resulting in cell death, accumulated autophagosomes and lysosomes, reduced mTORC1 signaling and synaptic connectivity, and lowered neurotransmitter contents of synaptic vesicles are observed in the brains of Atp6v0a1A512P/A512P mice. These findings demonstrate the essential roles of ATP6V0A1/Atp6v0a1 in neuronal development in terms of integrity and connectivity of neurons in both humans and mice.

Highlights

Vacuolar H+-ATPases (V-ATPases) transport protons across cellular membranes to acidify various organelles
We identified two individuals with biallelic ATP6V0A1 variants: individual 3 has a missense variant (c.1534G>C, p.(Ala512Pro)) and a 50-kb deletion involving ATP6V0A1 (del(17)(q21.2)), which were transmitted from his father and mother, respectively, and individual 4 has a splice site variant (c.196+1G>A) and a missense variant (c.1600A>G, p.(Asn534Asp)), which were transmitted from his father and mother, respectively (Fig. 1 and Supplementary Fig. 1)
We found that many TdT-mediated dUTP nick-end labeling (TUNEL)-positive cells were present in the cortex and hippocampus of Atp6v0a1A512P/A512P pups (Fig. 6a, b)

Summary

Introduction

Vacuolar H+-ATPases (V-ATPases) transport protons across cellular membranes to acidify various organelles. Lysosomal dysfunction resulting in cell death, accumulated autophagosomes and lysosomes, reduced mTORC1 signaling and synaptic connectivity, and lowered neurotransmitter contents of synaptic vesicles are observed in the brains of Atp6v0a1A512P/A512P mice These findings demonstrate the essential roles of ATP6V0A1/ Atp6v0a1 in neuronal development in terms of integrity and connectivity of neurons in both humans and mice. De novo variants in ATP6V1A have been recently shown in individuals with developmental and epileptic encephalopathy (DEE)[7] These suggest that various degrees of V-ATPase impairment cause disorders with a wide phenotypic spectrum. Lysosomal abnormalities, cell death, accumulated autophagosomes and lysosomes, downregulation of mTORC1 signaling, and reduced synaptic connectivity and neurotransmitter contents of synaptic vesicles are observed in mice harboring a homozygous missense variant identified in humans. Our data highlight the essential roles of the a1-subunit of the V0 domain of V-ATPase for brain development in terms of integrity and connectivity of neurons in both humans and mice

Methods

Results

Conclusion