Erg channel is critical in controlling cell volume during cell cycle in embryonic stem cells.
The cell cycle progression in mouse embryonic stem cells (mESCs) is controlled by ion fluxes that alter cell volume [1]. This suggests that ion fluxes might control dynamic changes in morphology over the cell cycle, such as rounding up of the cell at mitosis. However, specific channels regulating such dynamic changes and the possible interactions with actomyosin complex have not been clearly identified. Following RNAseq transcriptome analysis of cell cycle sorted mESCs, we found that expression of the K(+) ion channel Erg1 peaked in G1 cell cycle phase, which was confirmed by immunostaining. Inhibition of Erg channel activity caused loss of G1 phase cells via non-apoptotic cell death. Cells first lost the ability of membrane blebbing, a typical feature of cultured embryonic stem cells. Continued Erg inhibition further increased cell volume and the cell eventually ruptured. In addition, atomic force measurements on live cells revealed a decreased cortical stiffness after treatment, suggesting alterations in actomyosin organization. When the intracellular osmotic pressure was experimentally decreased by hypertonic solution or block of K(+) ion import via the Na, K-ATPase, cell viability was restored and cells acquired normal volume and blebbing activity. Our results suggest that Erg channels have a critical function in K(+) ion homeostasis of mESCs over the cell cycle, and that cell death following Erg inhibition is a consequence of the inability to regulate cell volume.
Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Shaimaa
S
Abdelhady
Satish Srinivas
SS
Kitambi
Vanessa
V
Lundin
Roland
R
Aufschnaiter
Petra
P
Sekyrova
Indranil
I
Sinha
Kalle T
KT
Lundgren
Goncalo
G
Castelo-Branco
Sten
S
Linnarsson
Roland
R
Wedlich-Söldner
Ana
A
Teixeira
Michael
M
Andäng
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002453:Cell Cycle / Q000502:physiology*; D048429:Cell Size; D053595:Embryonic Stem Cells / Q000166:cytology / Q000502:physiology*; D051638:Ether-A-Go-Go Potassium Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D007091:Image Processing, Computer-Assisted; D051379:Mice; D018625:Microscopy, Atomic Force; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D059008:Time-Lapse Imaging
D051638:Ether-A-Go-Go Potassium Channels; D012333:RNA, Messenger; D034741:RNA, Small Interfering