Synthesis of sterols and 5-lipoxygenase products are required for the G1-S phase transition of interleukin-2-dependent lymphocyte proliferation.
A murine killer T cell line, G-CTLL 1, whose proliferation depends on the presence of interleukin 2 (IL-2), was used to analyze the mechanism of IL-2 action with respect to sterol synthesis and arachidonate metabolism. De novo sterol synthesis was substantially enhanced much earlier than DNA synthesis, and the rate reached a maximum at 13 hr after the addition of IL-2. Compactin, which is a potent competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG CoA reductase, the enzyme in the rate-limiting step of the sterol synthesis), inhibited the IL-2-induced DNA synthesis. The addition of mevalonate, the product of HMG CoA reductase, prevented the inhibition of DNA synthesis by compactin, suggesting that the supply of a sufficient amount of sterol is an essential prerequisite for IL-2 action. The IL-2-induced DNA synthesis was also inhibited by AA861, a specific inhibitor of arachidonate 5-lipoxygenase, and by other lipoxygenase inhibitors such as nordihydroguaiaretic acid and esculetin. In contrast, indomethacin, an inhibitor of arachidonate cyclooxygenase, had no effect. These findings suggest that synthesis of 5-lipoxygenase products is also a prerequisite. The inhibition of DNA synthesis was effectively inhibited only when compactin or lipoxygenase inhibitors were added early enough to block the synthesis of sterols or 5-lipoxygenase products; addition of the reagents after 3 hr decreased the inhibition with time. Therefore, about 3 hr after the addition of IL-2, several drastic intracellular changes are assumed to begin and to lead to DNA synthesis.
D000818:Animals; D002453:Cell Cycle; D002455:Cell Division; D002460:Cell Line; D002999:Clone Cells / Q000166:cytology; D004247:DNA / Q000096:biosynthesis; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007376:Interleukin-2 / Q000494:pharmacology*; D050356:Lipid Metabolism; D008084:Lipoxygenase / Q000378:metabolism*; D016859:Lipoxygenase Inhibitors; D008148:Lovastatin / Q000031:analogs & derivatives / Q000494:pharmacology; D051379:Mice; D013261:Sterols / Q000096:biosynthesis*; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D013997:Time Factors
D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D007376:Interleukin-2; D016859:Lipoxygenase Inhibitors; D013261:Sterols; C012258:mevastatin; D004247:DNA; D008148:Lovastatin; D008084:Lipoxygenase