Crilly K S, Tomono M, Kiss Z
The Hormel Institute, University of Minnesota, 801 16th Avenue N.E., Austin, Minnesota 55912, USA.
Arch Biochem Biophys. 1998 Apr 1;352(1):137-43. doi: 10.1006/abbi.1998.0601.
In NIH 3T3 cells, phosphocholine (PCho) stimulates mitogenesis in synergism with insulin, ATP, and sphingosine-1-phosphate (S1P) via an extracellular target. Intracellular PCho also has been suggested to mediate the mitogenic effects of fibroblast growth factor (FGF) and several other growth factors based, in part, on the observed inhibition of growth factor-induced mitogenesis by the choline kinase inhibitor hemicholinium-3 (HC-3). Here we examined the specificity of HC-3 effects on mitogenesis in serum-starved NIH 3T3 and Swiss 3T3 cells. In both cell lines, FGF greatly enhanced DNA synthesis in a medium containing 28 microM choline, and it also stimulated the formation of -14C-PCho from both 50 microM and 5 mM [14C]choline. HC-3 (2 mM) inhibited basal or FGF-induced formation of [14C]PCho and [14C]phosphatidylcholine as well as the uptake of -14C-choline only at the 50 microM, but not the 5 mM, concentration of [14C]choline. In addition, HC-3 (1 mM) from three different sources (95-99.9% purity) inhibited FGF-stimulated DNA synthesis by 53-58% which was not reversed by 5 mM choline. The choline analogue dimethylethanolamine (1 mM) also inhibited FGF-stimulated formation of [14C]PCho from 50 microM -14C-choline, but it had no effect on FGF-induced DNA synthesis. Of the other growth regulators examined, synergistic stimulation of DNA synthesis by extracellular PCho and S1P or PCho and ATP via choline kinase-independent mechanisms was inhibited by 2 mM HC-3. However, HC-3 failed to inhibit the synergistic mitogenic effects of PCho and insulin or S1P and insulin. The results suggest that FGF-induced mitogenesis does not require PCho formation and that HC-3 can inhibit DNA synthesis independent of its inhibitory effects on choline metabolism.
在NIH 3T3细胞中，磷酸胆碱（PCho）通过细胞外靶点与胰岛素、ATP和鞘氨醇-1-磷酸（S1P）协同刺激有丝分裂。细胞内PCho也被认为部分介导了成纤维细胞生长因子（FGF）和其他几种生长因子的促有丝分裂作用，这部分基于胆碱激酶抑制剂半胱氨酸-3（HC-3）对生长因子诱导的有丝分裂的抑制作用。在此，我们研究了HC-3对血清饥饿的NIH 3T3和瑞士3T3细胞有丝分裂作用的特异性。在这两种细胞系中，FGF在含有28微摩尔胆碱的培养基中极大地增强了DNA合成，并且它还刺激了50微摩尔和5毫摩尔[14C]胆碱生成-14C-PCho。HC-3（2毫摩尔）仅在50微摩尔而非5毫摩尔的[14C]胆碱浓度下抑制基础或FGF诱导的[14C]PCho和[14C]磷脂酰胆碱的形成以及-14C-胆碱的摄取。此外，来自三种不同来源（纯度95 - 99.9%）的HC-3（1毫摩尔）将FGF刺激的DNA合成抑制了53 - 58%，而5毫摩尔胆碱不能逆转这种抑制作用。胆碱类似物二甲基乙醇胺（1毫摩尔）也抑制了FGF刺激的50微摩尔-14C-胆碱生成[14C]PCho，但对FGF诱导的DNA合成没有影响。在所检测的其他生长调节剂中，细胞外PCho和S1P或PCho和ATP通过不依赖胆碱激酶的机制对DNA合成的协同刺激被2毫摩尔HC-3抑制。然而，HC-3未能抑制PCho和胰岛素或S1P和胰岛素的协同促有丝分裂作用。结果表明，FGF诱导的有丝分裂不需要PCho的形成，并且HC-3可以独立于其对胆碱代谢的抑制作用来抑制DNA合成。
