Characterization of Ca(2+) signaling pathways in human mesenchymal stem cells.
Human mesenchymal stem cells (HMSC) have the potential to differentiate into many cell types. The physiological properties of HMSCs including their Ca(2+) signaling pathways, however, are not well understood. We investigated Ca(2+) influx and release functions in HMSCs. In Ca(2+) imaging experiments, spontaneous Ca(2+) oscillations were observed in 36 of 50 HMSCs. The Ca(2+) oscillations were completely blocked by the application of 10 micro M cyclopiazonic acid (CPA) or 1 micro M thapsigargin (TG). A brief application of 1 micro M acetylcholine (ACh) induced a transient increase of [Ca(2+)](i) but the application of caffeine (10 mM) did not induce any Ca(2+) transient. When the stores were depleted with Ca(2+)-ATPase blockers (CPA or TG) or muscarinic agonists (ACh), store-operated Ca(2+) (SOC) entry was observed. Using the patch-clamp technique, store-operated Ca(2+) currents (I(SOC)) could be recorded in cells treated with ACh or CPA, but voltage-operated Ca(2+) currents (VOCCs) were not elicited in most of the cells (17/20), but in 15% of cells examined, small dihydropyridine (DHP)-sensitive Ca(2+) currents were recorded. Using RT-PCR, mRNAs were detected for inositol 1,4,5-trisphosphate receptor (InsP(3)R) type I, II, and III and DHP receptors alpha1A and alpha1H were detected, but mRNA was not detected for ryanodine receptor (RyR) or N-type Ca(2+) channels. These results suggest that in undifferentiated HMSCs, Ca(2+) release is mediated by InsP(3)Rs and Ca(2+) entry through plasma membrane is mainly mediated by the SOCs channels with a little contribution of VOCCs.
Kawano
S
S
Department of Cardiovascular Diseases, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan. seiko-kawano@tmd.ac.jp
Shoji
S
S
Ichinose
S
S
Yamagata
K
K
Tagami
M
M
Hiraoka
M
M
D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D006801:Humans; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D018408:Patch-Clamp Techniques; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D022161:Transport Vesicles / Q000648:ultrastructure
D015220:Calcium Channels; D002118:Calcium