Calcium puffs are generic InsP(3)-activated elementary calcium signals and are downregulated by prolonged hormonal stimulation to inhibit cellular calcium responses.
Elementary Ca(2+) signals, such as "Ca(2+) puffs", which arise from the activation of inositol 1,4,5-trisphosphate receptors, are building blocks for local and global Ca(2+) signalling. We characterized Ca(2+) puffs in six cell types that expressed differing ratios of the three inositol 1,4,5-trisphosphate receptor isoforms. The amplitudes, spatial spreads and kinetics of the events were similar in each of the cell types. The resemblance of Ca(2+) puffs in these cell types suggests that they are a generic elementary Ca(2+) signal and, furthermore, that the different inositol 1,4,5-trisphosphate isoforms are functionally redundant at the level of subcellular Ca(2+) signalling. Hormonal stimulation of SH-SY5Y neuroblastoma cells and HeLa cells for several hours downregulated inositol 1,4,5-trisphosphate expression and concomitantly altered the properties of the Ca(2+) puffs. The amplitude and duration of Ca(2+) puffs were substantially reduced. In addition, the number of Ca(2+) puff sites active during the onset of a Ca(2+) wave declined. The consequence of the changes in Ca(2+) puff properties was that cells displayed a lower propensity to trigger regenerative Ca(2+) waves. Therefore, Ca(2+) puffs underlie inositol 1,4,5-trisphosphate signalling in diverse cell types and are focal points for regulation of cellular responses.
Tovey
S C
SC
Laboratory of Molecular Signalling, The Babraham Institute, Babraham, Cambridge, CB2 4AT, UK.
de Smet
P
P
Lipp
P
P
Thomas
D
D
Young
K W
KW
Missiaen
L
L
De Smedt
H
H
Parys
J B
JB
Berridge
M J
MJ
Thuring
J
J
Holmes
A
A
Bootman
M D
MD
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D015536:Down-Regulation; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*
D015220:Calcium Channels; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D020033:Protein Isoforms; D018160:Receptors, Cytoplasmic and Nuclear; D006632:Histamine; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D002217:Carbachol; D002118:Calcium