- 著者
- Mamoru Hayano Takeru Makiyama Tsukasa Kamakura Hiroshi Watanabe Kenichi Sasaki Shunsuke Funakoshi Yimin Wuriyanghai Suguru Nishiuchi Takeshi Harita Yuta Yamamoto Hirohiko Kohjitani Sayako Hirose Fumika Yokoi Jiarong Chen Osamu Baba Takahiro Horie Kazuhisa Chonabayashi Seiko Ohno Futoshi Toyoda Yoshinori Yoshida Koh Ono Minoru Horie Takeshi Kimura
- 出版者
- 日本循環器学会
- 雑誌
- Circulation Journal (ISSN:13469843)
- 巻号頁・発行日
- pp.CJ-17-0064, (Released:2017-06-20)
- 参考文献数
- 38
- 被引用文献数
- 23
Background:TheSCN5Agene encodes the α subunit of the cardiac voltage-gated sodium channel, NaV1.5. The missense mutation, D1275N, has been associated with a range of unusual phenotypes associated with reduced NaV1.5 function, including cardiac conduction disease and dilated cardiomyopathy. Curiously, the reported biophysical properties ofSCN5A-D1275N channels vary with experimental system.Methods and Results:First, using a human embryonic kidney (HEK) 293 cell-based heterologous expression system, theSCN5A-D1275N channels showed similar maximum sodium conductance but a significantly depolarizing shift of activation gate (+10 mV) compared to wild type. Second, we generated human-induced pluripotent stem cells (hiPSCs) from a 24-year-old female who carried heterozygousSCN5A-D1275N and analyzed the differentiated cardiomyocytes (CMs). AlthoughSCN5Atranscript levels were equivalent between D1275N and control hiPSC-CMs, both the total amount of NaV1.5 and the membrane fractions were reduced approximately half in the D1275N cells, which were rescued by the proteasome inhibitor MG132 treatment. Electrophysiological assays revealed that maximum sodium conductance was reduced to approximately half of that in control hiPSC-CMs in the D1275N cells, and maximum upstroke velocity of action potential was lower in D1275N, which was consistent with the reduced protein level of NaV1.5.Conclusions:This study successfully demonstrated diminished sodium currents resulting from lower NaV1.5 protein levels, which is dependent on proteasomal degradation, using a hiPSC-based model forSCN5A-D1275N-related sodium channelopathy.
- 著者
- Tsukasa Kamakura Takeru Makiyama Kenichi Sasaki Yoshinori Yoshida Yimin Wuriyanghai Jiarong Chen Tetsuhisa Hattori Seiko Ohno Toru Kita Minoru Horie Shinya Yamanaka Takeshi Kimura
- 出版者
- 日本循環器学会
- 雑誌
- Circulation Journal (ISSN:13469843)
- 巻号頁・発行日
- pp.CJ-12-0987, (Released:2013-02-09)
- 参考文献数
- 34
- 被引用文献数
- 28 221
Background: In the short- to mid-term, cardiomyocytes generated from human-induced pluripotent stem cells (hiPSC-CMs) have been reported to be less mature than those of adult hearts. However, the maturation process in a long-term culture remains unknown. Methods and Results: A hiPSC clone generated from a healthy control was differentiated into CMs through embryoid body (EB) formation. The ultrastructural characteristics and gene expressions of spontaneously contracting EBs were analyzed through 1-year of culture after cardiac differentiation was initiated. The 14-day-old EBs contained a low number of myofibrils, which lacked alignment, and immature high-density Z-bands lacking A-, H-, I-, and M-bands. Through the long-term culture up to 180 days, the myofibrils became more tightly packed and formed parallel arrays accompanied by the appearance of mature Z-, A-, H-, and I-bands, but not M-bands. Notably, M-bands were finally detected in 360-day-old EBs. The expression levels of the M-band-specific genes in hiPSC-CMs remained lower in comparison with those in the adult heart. Immunocytochemistry indicated increasing number of MLC2v-positive/MLC2a-negative cells with decreasing number of MLC2v/MLC2a double-positive cells, indicating maturing of ventricular-type CMs. Conclusions: The structural maturation process of hiPSC-CMs through 1-year of culture revealed ultrastructural sarcomeric changes accompanied by delayed formation of M-bands. Our study provides new insight into the maturation process of hiPSC-CMs.