Extracellular ATP-induced nuclear Ca2+ transient is mediated by inositol 1,4,5-trisphosphate receptors in mouse pancreatic beta-cells.
Extracellular ATP (eATP) induces an intracellular Ca(2+) transient by activating phospholipase C (PLC)-associated P2X4 purinergic receptors, leading to production of inositol 1,4,5-trisphosphate (IP3) and subsequent Ca(2+) release from intracellular stores in mouse pancreatic beta-cells. Using laser scanning confocal microscopy, Ca(2+) indicator fluo-4 AM, and the cell permeable nuclear indicator Hoechst 33342, we examined the properties of eATP-induced Ca(2+) release in pancreatic beta-cell nuclei. eATP induced a higher nuclear Ca(2+) transient in pancreatic beta-cell nuclei than in the cytosol. After pretreatment with thapsigargin (TG), an inhibitor of sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) pumps, the amplitude of eATP-induced Ca(2+) transients in the nucleus was still much higher than those in the cytosol. This effect of eATP was not altered by inhibition of either the plasma membrane Ca(2+)-ATPase (PMCA) or the plasma membrane Na(+)/Ca(2+) exchanger (NCX) by LaCl(3) or by replacement of Na(+) with N-Methyl-Glucosamine. eATP-induced nuclear Ca(2+) transients were abolished by a cell-permeable IP3R inhibitor, 2-aminoethoxydiphenyl borate (2-APB), but were not blocked by the ryanodine receptor (RyR) antagonist ryanodine. Immunofluorescence studies showed that IP3Rs are expressed on the nuclear envelope of pancreatic beta-cells. These results indicate that eATP triggers nuclear Ca(2+) transients by mobilizing a nuclear Ca(2+) store via nuclear IP3Rs.
Chen
Zheng
Z
National Laboratory of Biomacromolecules, Institute of Biophysics of Chinese Academy of Sciences, Beijing, China.
Li
Zhengzheng
Z
Peng
Gong
G
Chen
Xiaoli
X
Yin
Wenxuan
W
Kotlikoff
Michael I
MI
Yuan
Zeng-Qiang
ZQ
Ji
Guangju
G
D000255:Adenosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001562:Benzimidazoles / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002467:Cell Nucleus / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D053499:Plasma Membrane Calcium-Transporting ATPases / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism
C506944:Atp2a1 protein, mouse; D001562:Benzimidazoles; D005456:Fluorescent Dyes; D053496:Inositol 1,4,5-Trisphosphate Receptors; D000255:Adenosine Triphosphate; D053499:Plasma Membrane Calcium-Transporting ATPases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506954:Atp2b1 protein, mouse; C017807:bisbenzimide ethoxide trihydrochloride; D002118:Calcium