TY - JOUR
T1 - Requirement of Ca2+ for the production and degradation of inositol 1,4,5-trisphosphate in macrophages
AU - Kukita, Masataka
AU - Hirata, Masato
AU - Koga, Toshitaka
N1 - Funding Information:
This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan. We thank K. Higuchi for secretarial services.
PY - 1986/1/23
Y1 - 1986/1/23
N2 - The requirement of Ca2+ for the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdInsP2) or the accumulation of inositol 1,4,5-trisphosphate (InsP3) in macrophages stimulated with fMet-Leu-Phe was examined using [32P]Pi or [3H]inositol-labeled cells. The dependence on Ca2+ of inositol-trisphosphate phosphatase was also examined. The application of 1·10-8 M fMet-Leu-Phe caused a rapid decrease in the amount of PtdInsP2 to 70% of the control within 10 s, and the decrease was reverted to the control level by prolonged incubation. The decrease in the amount of PtdInsP2 accompanied the accumulation of phosphatidic acid and of InsP3, indicating that the loss of PtdInsP2 is due to phosphodiesteric breakdown. The dose-dependence of fMet-Leu-Phe or its analog on the hydrolysis of PtdInsP2 was much the same as that of the increase in intracellular free Ca2+ concentration in macrophages. The loss of PtdInsP2 as induced by fMet-Leu-Phe was similarly observed in macrophages treated with ionophore A23187 in the absence of external Ca2+ for 10 min. InsP3 was degraded by the particulate or cytosol fraction prepared from macrophages, and the activity of inositol-trisphosphate phosphatase in the particulate fraction was higher than that in the cytosol fraction. The enzyme in the cytosol fraction required Mg2+ for activity, and was activated by free Ca2+ concentrations ranging from 10-7 to 10-6 M in the presence of 1 mM MgCl2.
AB - The requirement of Ca2+ for the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdInsP2) or the accumulation of inositol 1,4,5-trisphosphate (InsP3) in macrophages stimulated with fMet-Leu-Phe was examined using [32P]Pi or [3H]inositol-labeled cells. The dependence on Ca2+ of inositol-trisphosphate phosphatase was also examined. The application of 1·10-8 M fMet-Leu-Phe caused a rapid decrease in the amount of PtdInsP2 to 70% of the control within 10 s, and the decrease was reverted to the control level by prolonged incubation. The decrease in the amount of PtdInsP2 accompanied the accumulation of phosphatidic acid and of InsP3, indicating that the loss of PtdInsP2 is due to phosphodiesteric breakdown. The dose-dependence of fMet-Leu-Phe or its analog on the hydrolysis of PtdInsP2 was much the same as that of the increase in intracellular free Ca2+ concentration in macrophages. The loss of PtdInsP2 as induced by fMet-Leu-Phe was similarly observed in macrophages treated with ionophore A23187 in the absence of external Ca2+ for 10 min. InsP3 was degraded by the particulate or cytosol fraction prepared from macrophages, and the activity of inositol-trisphosphate phosphatase in the particulate fraction was higher than that in the cytosol fraction. The enzyme in the cytosol fraction required Mg2+ for activity, and was activated by free Ca2+ concentrations ranging from 10-7 to 10-6 M in the presence of 1 mM MgCl2.
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U2 - 10.1016/0167-4889(86)90046-7
DO - 10.1016/0167-4889(86)90046-7
M3 - Article
C2 - 3002487
AN - SCOPUS:0023055406
SN - 0167-4889
VL - 885
SP - 121
EP - 128
JO - Biochimica et Biophysica Acta - Molecular Cell Research
JF - Biochimica et Biophysica Acta - Molecular Cell Research
IS - 1
ER -