title: Junctophilin 2 knockdown interfere with mitochondrium status in ESC-CMs and cardiogenesis of ES cells.
abstract: In the present study, we explored the possible links between Junctophilin 2 (Jp2) and the mitochondrium-sarcoplasmic reticulum (SR) interaction in embryonic stem cell-derived cardiomyocytes (ESC-CMs), as well as the role of Jp2 in cardiogenesis of ES cells. We found that Ca(2+) transient was abnormal and mitochondria were de-energized within siJp2 ESC-CMs. The essential juxtaposition structure of mitochondrium with SR was destroyed accompanied by selectively downregulation of Pgc-1α, Nrf-1, and Mfn-2. Impaired co-localization of the JP2 and sarcomeres (α-Actinin or Troponin-T) appeared in embryoid bodies (EBs) after Jp2 knockdown. Calsequestrin2 and ryanodine receptor 2 within SR were expressed as early as the initiation of differentiation, while triadin and caveolin3 within t-tubules (TTs) did not appear until the terminal, indicating that JP2 probably did not contribute to anchoring the SR to TTs at the early cardiogenesis stage as usual. In addition, Jp2 knockdown selectively decreased gene transcription toward cardiogenesis (Brachyury, Isl1, and Nkx2.5), subsequently weaken EB beating activity by 60%. Taken together, reducing JP2 expression in ESC-CMs resulted in impaired mitochondrial status due to either abnormal cellular Ca(2+) homeostasis or disturbing of juxtaposition. A sensitive time window of JP2 necessary in cardiac differentiation was found at early stage via an extra non-TTs/SR anchor-dependent role.
authors.affiliation: Division of Cardio-Cerebral Vascular and Hepatic Pharmacology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Xingguang
authors.initials: X
authors.lastname: Liang
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Mei
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
authors.forename: Guofang
authors.initials: G
authors.lastname: Shen
authors.forename: Danyan
authors.initials: D
authors.lastname: Zhu
authors.forename: Yongping
authors.initials: Y
authors.lastname: Yu
authors.forename: Jianan
authors.initials: J
authors.lastname: Wang
authors.forename: Yijia
authors.initials: Y
authors.lastname: Lou
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D058732:Embryoid Bodies / Q000378:metabolism / Q000648:ultrastructure; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D005434:Flow Cytometry; D007150:Immunohistochemistry; D053078:Membrane Potential, Mitochondrial / Q000235:genetics / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000648:ultrastructure; D034741:RNA, Small Interfering / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D008565:Membrane Proteins; D034741:RNA, Small Interfering; C412507:junctophilin