Phospholipase C-β1 and β4 contribute to non-genetic cell-to-cell variability in histamine-induced calcium signals in HeLa cells.
A uniform extracellular stimulus triggers cell-specific patterns of Ca(2+) signals, even in genetically identical cell populations. However, the underlying mechanism that generates the cell-to-cell variability remains unknown. We monitored cytosolic inositol 1,4,5-trisphosphate (IP3) concentration changes using a fluorescent IP3 sensor in single HeLa cells showing different patterns of histamine-induced Ca(2+) oscillations in terms of the time constant of Ca(2+) spike amplitude decay and the Ca(2+) oscillation frequency. HeLa cells stimulated with histamine exhibited a considerable variation in the temporal pattern of Ca(2+) signals and we found that there were cell-specific IP3 dynamics depending on the patterns of Ca(2+) signals. RT-PCR and western blot analyses showed that phospholipase C (PLC)-β1, -β3, -β4, -γ1, -δ3 and -ε were expressed at relatively high levels in HeLa cells. Small interfering RNA-mediated silencing of PLC isozymes revealed that PLC-β1 and PLC-β4 were specifically involved in the histamine-induced IP3 increases in HeLa cells. Modulation of IP3 dynamics by knockdown or overexpression of the isozymes PLC-β1 and PLC-β4 resulted in specific changes in the characteristics of Ca(2+) oscillations, such as the time constant of the temporal changes in the Ca(2+) spike amplitude and the Ca(2+) oscillation frequency, within the range of the cell-to-cell variability found in wild-type cell populations. These findings indicate that the heterogeneity in the process of IP3 production, rather than IP3-induced Ca(2+) release, can cause cell-to-cell variability in the patterns of Ca(2+) signals and that PLC-β1 and PLC-β4 contribute to generate cell-specific Ca(2+) signals evoked by G protein-coupled receptor stimulation.
Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Japan.
Sachiko
S
Ishida
Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Japan.
Toru
T
Matsu-Ura
Laboratory of Genome and Biosignal, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan.
Kiyoko
K
Fukami
Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Japan ; Calcium Oscillation Project, ICORP-SORST, Japan Science and Technology Agency, Kawaguchi, Japan ; Laboratory for Behavioral Genetics, RIKEN Brain Science Institute, Wako, Japan.
Takayuki
T
Michikawa
Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Japan ; Calcium Oscillation Project, ICORP-SORST, Japan Science and Technology Agency, Kawaguchi, Japan.
Katsuhiko
K
Mikoshiba
D015153:Blotting, Western; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D006367:HeLa Cells; D006632:Histamine / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D054799:Phospholipase C beta / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D007527:Isoenzymes; D034741:RNA, Small Interfering; D043562:Receptors, G-Protein-Coupled; D006632:Histamine; D015544:Inositol 1,4,5-Trisphosphate; D054799:Phospholipase C beta