Transient receptor potential melastatin 4 channel controls calcium signals and dental follicle stem cell differentiation.
Elevations in the intracellular Ca(2+) concentration are a phenomena commonly observed during stem cell differentiation but cease after the process is complete. The transient receptor potential melastatin 4 (TRPM4) is an ion channel that controls Ca(2+) signals in excitable and nonexcitable cells. However, its role in stem cells remains unknown. The aim of this study was to characterize TRPM4 in rat dental follicle stem cells (DFSCs) and to determine its impact on Ca(2+) signaling and the differentiation process. We identified TRPM4 gene expression in DFSCs, but not TRPM5, a closely related channel with similar function. Perfusion of cells with increasing buffered Ca(2+) resulted in a concentration-dependent activation of currents typical for TRPM4, which were also voltage-dependent and had Na(+) conductivity. Molecular suppression with shRNA decreased channel activity and cell proliferation during osteogenesis but not adipogenesis. As a result, enhanced mineralization and phosphatase enzyme activity were observed during osteoblast formation, although DFSCs failed to differentiate into adipocytes. Furthermore, the normal agonist-induced first and secondary phases of Ca(2+) signals were transformed into a gradual and sustained increase which confirmed the channels' ability to control Ca(2+) signaling. Using whole genome microarray analysis, we identified several genes impacted by TRPM4 during DFSC differentiation. These findings suggest an inhibitory role for TRPM4 on osteogenesis while it appears to be required for adipogenesis. The data also provide a potential link between the Ca(2+) signaling pattern and gene expression during stem cell differentiation.
Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Piper
P
Nelson
Tran Doan
TD
Ngoc Tran
Hanjie
H
Zhang
Olga
O
Zolochevska
Marxa
M
Figueiredo
Ji-Ming
JM
Feng
Dina L
DL
Gutierrez
Rui
R
Xiao
Shaomian
S
Yao
Arthur
A
Penn
Li-Jun
LJ
Yang
Henrique
H
Cheng
D050156:Adipogenesis / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D003795:Dental Sac / Q000378:metabolism*; D008564:Membrane Potentials; D010012:Osteogenesis / Q000502:physiology; D018408:Patch-Clamp Techniques; D034622:RNA Interference; D034741:RNA, Small Interfering; D051381:Rats; D017207:Rats, Sprague-Dawley; D013234:Stem Cells / Q000378:metabolism*; D050053:TRPM Cation Channels / Q000235:genetics / Q000378:metabolism*; D014070:Tooth / Q000378:metabolism
D015220:Calcium Channels; D034741:RNA, Small Interfering; D050053:TRPM Cation Channels; C500239:TRPM4 protein, rat; D002118:Calcium