The diacylglycerol analogue, 1,2-sn-dioctanoylglycerol, induces an increase in cytosolic free Ca2+ and cytosolic acidification of T lymphocytes through a protein kinase C-independent process

R. Ebanks, C. Roifman, A. Mellors, Gordon Mills

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Abstract

In this paper, we demonstrate that low concentrations (0.5-2.5 μM) of 1,2-sn-dioctanoylglycerol (DiC8), a potent diacylglycerol used in many previous studies to probe the role of protein kinase (PKC) in cell activation, cause cytosolic alkalinization of human, mouse and pig T lymphocytes through PKC-mediated activation of the Na+/H+ antiport. However, at higher concentrations (≥ 12.5 μM), the effect on cytosolic pH (pH(i)) is reversed, resulting in a marked cytosolic acidification, followed by a gradual return of pH(i) to baseline values. DiC8 also induces marked changes in cytosolic free calcium concentrations ([Ca2+](i)), initially by releasing calcium from intracellular stores, followed by a net transmembrane influx of calcium. The DiC8-induced cytosolic acidification, the resultant return to baseline pH and the increase in [Ca2+](i) are independent of activation of PKC. Unlike many other agents which increase [Ca2+](i), DiC8 does not induce phosphatidylinositol hydrolysis with the resultant production of inositol phosphates. Other compounds known to activate PKC, including the closely related diacylglycerol analogues, 1,2-sn-dihexanoylglycerol and 1,2-sn-didecanoylglycerol, phorbol esters and mezerein, did not induce changes in [Ca2+](i) or cytosolic acidification in T lymphocytes. Thus the action of DiC8 on intact lymphocytes is different from that of phorbol esters and other diacylglycerols, and is specific to the length of the acyl chains. Because changes in [Ca2+](i) are often associated with cell proliferation and cell differentiation, some effects of DiC8 on intact cells may be a consequence of changes in [Ca2+](i).

Original languageEnglish (US)
Pages (from-to)689-698
Number of pages10
JournalBiochemical Journal
Volume258
Issue number3
Publication statusPublished - Jan 1 1989
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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