2019 Fiscal Year Research-status Report
心室細動発症におけるTMEM168遺伝子変異解析とトラスレーショナル研究への応用
| Project/Area Number |
18K08033
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| Research Institution | National Cardiovascular Center Research Institute |
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Principal Investigator |
ZANKOV DimitarP 国立研究開発法人国立循環器病研究センター, 研究所, 室長 (20631295)
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| Co-Investigator(Kenkyū-buntansha) |
扇田 久和 滋賀医科大学, 医学部, 教授 (50379236)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | Brugada syndrome / TMEM168 |
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| Outline of Annual Research Achievements |
Exome sequencing identified new heterozygous variant in TMEM168 gene (1616G>A) among family members clinically diagnosed as Brugada syndrome. Human variant of TMEM168 was cloned in order to analyze its so far unknown function. Confocal images show that TMEM168 protein was located in the nuclear membrane of CHO and HL-1 cells. Western blots could detect TMEM168 proteins only in the nuclear fractions of the cells. HL-1 cells expressing mutant TMEM168, possessed decreased density of endogenous Na current and Nav1.5 protein in the cell membrane in contrast with the cells expressing wild type TMEM168.
We generated knock-in mice incorporating the same TMEM168 variant as in the studied Brugada family. In TMEM168 variant hearts Na channel blocker ajmaline was able to induce ST segment elevation in right precordial leads and ventricular arrhythmias. Isolated ventricular myocytes (like HL-1 cells) show reduced Na current and Nav1.5 in the TMEM168 variant hearts.
We found unusual and unreported so far mechanism for Nav1.5 modulation by nuclear membrane protein. Degradation of Nav1.5 is promoted by enhanced activity of Nav1.5-associated Nedd4-2 ubiquitin ligase in the knock-in hearts with mutant TMEM168.
The above data suggest involvement of TMEM168 in cardiac electrophysiology and possible relation to Brugada syndrome.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
1. Significant focus on the study by all collaborators.
2. We obtained successfully supportive data to advance the project.
3. The project at its current status is published in the FASEB journal.(https://faseb.onlinelibrary.wiley.com/doi/full/10.1096/fj.201902991R).
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| Strategy for Future Research Activity |
1. Because the mutation in TMEM168 is identified in Brugada syndrome, it is of significant interest to make an attempt to uncover the physiological role of this gene. RNA sequencing of samples from wild type and knock-in (1616G>A) TMEM168 hearts might suggest the further direction and identify functional partners of TMEM168. 2. Unresolved question is the the relationship between clinical Brugada syndrome and TMEM168 mutations. I plan to search for TMEM168 variants in Brugada syndrome patients without genetic diagnosis.
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| Causes of Carryover |
Moving from old to new building of NCVC laboratory.
Plan: purchase articles for experimental work.
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Research Products
(2 results)
