ABSTRACT
Dysfunction of glucose transporter 1 (GLUT1) proteins causes infantile epilepsy, which is designated as a GLUT1 deficiency syndrome (GLUT1DS; OMIM #606777). Patients with GLUT1DS display varied clinical phenotypes, such as infantile seizures, ataxia, severe mental retardation with learning disabilities, delayed development, hypoglycorrhachia, and other varied symptoms. Glut1Rgsc200 mutant mice mutagenized with N-ethyl-N-nitrosourea (ENU) carry a missense mutation in the Glut1 gene that results in amino acid substitution at the 324th residue of the GLUT1 protein. In this study, these mutants exhibited various phenotypes, including embryonic lethality of homozygotes, a decreased cerebrospinal-fluid glucose value, deficits in contextual learning, a reduction in body size, seizure-like behavior and abnormal electroencephalogram (EEG) patterns. During EEG recording, the abnormality occurred spontaneously, whereas the seizure-like phenotypes were not observed at the same time. In sleep-wake analysis using EEG recording, heterozygotes exhibited a longer duration of wake times and shorter duration of non-rapid eye movement (NREM) sleep time. The shortened period of NREM sleep and prolonged duration of the wake period may resemble the sleep disturbances commonly observed in patients with GLUT1DS and other epilepsy disorders. Interestingly, an in vivo kinetic analysis of glucose utilization by positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-D-glucose imaging revealed that glucose transportation was reduced, whereas hexokinase activity and glucose metabolism were enhanced. These results indicate that a Glut1Rgsc200 mutant is a useful tool for elucidating the molecular mechanisms of GLUT1DS.
This article has an associated First Person interview with the joint first authors of the paper.
Footnotes
Competing interests
The authors declare no competing or financial interests.
Author contributions
Conceptualization: T.F., H. Mizuma, H. Masuya, H.O., S.W.; Methodology: T.F., H. Mizuma, Y.H., T.K., I.Y., I.M.; Software: H. Masuya; Validation: T.F., H. Mizuma, Y.H., H.F.; Formal analysis: T.F., H. Mizuma, Y.H., T.K., I.Y., I.M.; Investigation: H.O., S.W.; Data curation: T.F., H. Mizuma, Y.H.; Writing - original draft: T.F., H. Mizuma, Y.H.; Writing - review & editing: T.F., H. Mizuma, Y.H.; Visualization: H. Mizuma, Y.H.; Supervision: H. Masuya, H.F., M.Y., H.O., S.W.; Project administration: H. Masuya, M.Y., H.O., S.W.; Funding acquisition: T.F., M.Y.
Funding
This study was supported by the KAKENHI from the Japan Society for the Promotion of Science (JSPS) (grant numbers 17H06095 to M.Y.; 17K07144 to T.F.), the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program) from the Cabinet Office and the JSPS, Japan (to M.Y.), and the World Premier International Research Center Initiative (WPI) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan (to M.Y.).
Data availability
The mutant mouse used in this study (RBRC No.: RBRC-GSC0242) is available from Experimental Animal Division, RIKEN BioResource Research Center (https://mus.brc.riken.jp/en/).
Supplementary information
Supplementary information available online at http://dmm.biologists.org/lookup/doi/10.1242/dmm.038828.supplemental
- Received January 9, 2019.
- Accepted July 30, 2019.
- © 2019. Published by The Company of Biologists Ltd
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
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