Hollande F, Combettes S, Bali J P, Magous R
Laboratorie de Biochimie des Membranes, Contrat Jeune Formation Institute National de la Sante et de la Recherche Medicale, Montpellier, France.
Am J Physiol. 1996 Mar;270(3 Pt 1):G463-9. doi: 10.1152/ajpgi.1996.270.3.G463.
This work aimed to investigate the molecular role of gastrin in histamine synthesis in isolated rabbit fundic mucosal cells enriched in enterochromaffin-like (ECL) cells (37%). Gastrin stimulated histidine decarboxylase (HDC) activity by increasing the maximal velocity (Vmax) from 0.240 +/- 0.017 (basal value) to 0.332 +/- 0.012 pmol/mg protein/h and by decreasing the Michaelis-Menten constant value -Km; 73.90 +/- 2.2 vs. 93.42 +/- 4.32 microM (basal value)]. Pertussis toxin (PTX) (200 ng/ml) reduced the stimulation of HDC induced by 10 nM gastrin from 41.8 to 15.9%, whereas cholera toxin (CTX) (100 ng/ml) was without effect. Staurosporine and polymyxin B inhibited in a dose dependent manner the HDC activity stimulated by 10 nM gastrin. Phorbol 12-myristate 13-acetate (PMA; 100 nM) decreased Vmax (0.558 +/- 0.021 pmol/ mg protein/h) but did not change the Km. Furthermore, cycloheximide (0.1-10 microM) inhibited the gastrin-induced stimulation of HDC activity, whereas actinomycin D (up to 10 microM) was without effect. Finally, incubation of cells with gastrin (10 microM) left the expression of HDC mRNA unchanged. We concluded that gastrin, acting through "gastrin/CCK-B type" receptors coupled to PTX-sensitive G protein, exerts a short-term regulation of histamine synthesis in gastric ECL cells by increasing both the affinity of HDC for L-histidine and the number of active enzyme molecules. This last event, related to protein kinase C activation, could be due to a translational or posttranslational mechanism.
这项研究旨在探讨胃泌素在富含肠嗜铬样（ECL）细胞（37%）的离体兔胃底黏膜细胞组胺合成中的分子作用。胃泌素通过将最大反应速度（Vmax）从0.240±0.017（基础值）提高到0.332±0.012 pmol/mg蛋白/小时，并降低米氏常数（Km）值[73.90±2.2对93.42±4.32 μM（基础值）]来刺激组氨酸脱羧酶（HDC）活性。百日咳毒素（PTX）（200 ng/ml）将10 nM胃泌素诱导的HDC刺激从41.8%降低到15.9%，而霍乱毒素（CTX）（100 ng/ml）则无作用。星形孢菌素和多粘菌素B以剂量依赖性方式抑制10 nM胃泌素刺激的HDC活性。佛波酯12-肉豆蔻酸酯13-乙酸酯（PMA；100 nM）降低了Vmax（0.558±0.021 pmol/mg蛋白/小时），但未改变Km。此外，放线菌酮（0.1 - 10 μM）抑制胃泌素诱导的HDC活性刺激，而放线菌素D（高达10 μM）则无作用。最后，用胃泌素（10 μM）孵育细胞后，HDC mRNA的表达未改变。我们得出结论，胃泌素通过与PTX敏感的G蛋白偶联的“胃泌素/CCK-B型”受体起作用，通过增加HDC对L-组氨酸的亲和力和活性酶分子数量，对胃ECL细胞中的组胺合成进行短期调节。最后这一事件与蛋白激酶C激活有关，可能是由于翻译或翻译后机制。
