Hagelüken A, Grünbaum L, Klinker J F, Nürnberg B, Harhammer R, Schultz G, Leschke C, Schunack W, Seifert R
Institut für Pharmakologie, Freie Universität Berlin, Germany.
Biochem Pharmacol. 1995 Mar 30;49(7):901-914. doi: 10.1016/0006-2952(94)00514-m.
In dibutyryl cAMP-differentiated human leukemia (HL-60) cells, the potent histamine H1-receptor agonist, 2-(3-chlorophenyl)histamine, activates pertussis toxin (PTX)-sensitive guanine nucleotide-binding proteins (G-proteins) of the Gi-subfamily by a mechanism which is independent of known histamine receptor subtypes (Seifert et al. Mol Pharmacol 45: 578-586, 1994). In order to learn more about this G-protein activation, we studied the effects of histamine and various 2-substituted histamine derivatives in various cell types and on purified G-proteins. In HL-60 cells, histamine and 2-methylhistamine increased cytosolic Ca2+ concentration ([Ca2+]i) in a clemastine-sensitive manner. Phenyl- and thienyl-substituted histamines increased [Ca2+]i as well, but their effects were not inhibited by histamine receptor antagonists. 2-Substituted histamines activated high-affinity GTPase in HL-60 cell membranes in a PTX-sensitive manner, with the lipophilicity of substances increasing their effectiveness. Although HEL cells do not possess histamine receptors mediating rises in [Ca2+]i, 2-(3-bromophenyl)histamine increased [Ca2+]i in a PTX-sensitive manner. It also increased GTP hydrolysis by Gi-proteins in HEL cell membranes. All these stimulatory effects of 2-substituted histamine derivatives were seen at concentrations higher than those required for activation of H1-receptors. In various other cell types and membrane systems, 2-substituted histamine derivatives showed no or only weak stimulatory effects on G-proteins. 2-Substituted histamine derivatives activated GTP hydrolysis by purified bovine brain Gi/Go-proteins and by pure Gi2 (the major PTX-sensitive G-protein in HL-60 and HEL cells). Our data suggest the following: (1) histamine and 2-methylhistamine act as H1-receptor agonists in HL-60 cells; (2) incorporation of bulky and lipophilic groups results in loss of H1-agonistic activity of 2-substituted histamine derivatives in HL-60 cells but causes a receptor-independent G-protein-stimulatory activity; (3) the effects of 2-substituted histamine derivatives on G-proteins are cell-type specific.
在二丁酰环磷腺苷分化的人白血病（HL-60）细胞中，强效组胺H1受体激动剂2-（3-氯苯基）组胺通过一种独立于已知组胺受体亚型的机制激活Gi亚家族的百日咳毒素（PTX）敏感鸟嘌呤核苷酸结合蛋白（G蛋白）（Seifert等人，《分子药理学》45:578 - 586，1994）。为了更多地了解这种G蛋白激活，我们研究了组胺和各种2-取代组胺衍生物在各种细胞类型中以及对纯化G蛋白的作用。在HL-60细胞中，组胺和2-甲基组胺以一种对氯马斯汀敏感的方式增加胞质Ca2+浓度（[Ca2+]i）。苯基和噻吩基取代的组胺也增加了[Ca2+]i，但其作用不受组胺受体拮抗剂的抑制。2-取代组胺以PTX敏感的方式激活HL-60细胞膜中的高亲和力GTP酶，物质的亲脂性增加了其有效性。尽管HEL细胞不具有介导[Ca2+]i升高的组胺受体，但2-（3-溴苯基）组胺以PTX敏感的方式增加了[Ca2+]i。它还增加了HEL细胞膜中Gi蛋白的GTP水解。2-取代组胺衍生物的所有这些刺激作用在高于激活H1受体所需的浓度下可见。在各种其他细胞类型和膜系统中，2-取代组胺衍生物对G蛋白没有或只有微弱的刺激作用。2-取代组胺衍生物激活纯化的牛脑Gi/Go蛋白以及纯Gi2（HL-60和HEL细胞中主要的PTX敏感G蛋白）的GTP水解。我们的数据表明如下：（1）组胺和2-甲基组胺在HL-60细胞中作为H1受体激动剂起作用；（2）引入庞大和亲脂性基团导致HL-60细胞中2-取代组胺衍生物失去H1激动活性，但产生一种不依赖受体的G蛋白刺激活性；（3）2-取代组胺衍生物对G蛋白的作用具有细胞类型特异性。
