Glutamine metabolism stimulates intestinal cell MAPKs by a cAMP-inhibitable, Raf-independent mechanism
Glutamine metabolism stimulates intestinal cell MAPKs by a cAMP-inhibitable, Raf-independent mechanism
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DOI：
10.1016/s0016-5085(00)70417-3
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发表时间：
2000-01-01
期刊：
影响因子：
29.4
通讯作者：
Brenner, DA
中科院分区：
文献类型：
--
作者：
Rhoads, JM;Argenzio, RA;Brenner, DA
背景和目标：由病毒加肠毒素细菌引起的感染性腹泻通常比单独由任何一种病原体引起的腹泻更严重。我们推测，在肠道致病微生物感染期间观察到的细胞腺苷3 '，5'-环磷酸（cAMP）浓度增加通过阻断增殖肠细胞中促分裂原活化蛋白激酶（MAPK）的活化来延缓肠修复过程。我们评估了谷氨酰胺对MAPK活性、胸苷掺入、谷氨酰胺饥饿和谷氨酰胺充足的大鼠肠隐窝细胞（IEC-6）中的细胞数。在谷氨酰胺饥饿的细胞中，10 mmol/L谷氨酰胺在无血清的情况下刺激[H-3]胸苷掺入8倍，用8-（4-氯苯硫基）（8-CPT）-cAMP（100 μ mol/L）+异丁基甲基黄嘌呤（100 μ mol/L）可抑制60%。在未饥饿谷氨酰胺的细胞中，谷氨酰胺刺激胸苷掺入3倍，8-CPT-cAMP完全阻断促有丝分裂作用，cAMP对增殖的抑制作用在cAMP去除后持续至少68小时。体外激酶测定表明，谷氨酰胺信号传导需要未饥饿细胞中完整的ERK（细胞外信号相关激酶）途径。在饥饿的细胞中，谷氨酰胺至少激活了另一条途径（JNK），8-CPT-cAMP对有丝分裂的抑制是不完全的，其他肠燃料（葡萄糖和乙酸）不具有促有丝分裂作用。结论：细胞内cAMP水平的升高抑制了ERK，但仅部分降低了谷氨酰胺刺激的肠细胞增殖。
Background & Aims: Infectious diarrhea caused by viruses plus enterotoxigenic bacteria is often more severe than diarrhea induced by either pathogen alone. We postulated that the increased cell adenosine 3',5'-cyclic monophosphate (cAMP) concentration observed during infection by enterotoxigenic organisms retards the intestinal repair process by blocking activation of mitogen-activated protein kinases (MAPKs) in proliferating intestinal cells, Methods: We evaluated the effects of glutamine on MAPK activity, thymidine incorporation, and cell number in glutamine-starved and -sufficient rat intestinal crypt cells (IEC-6), Results: In glutamine-starved cells, 10 mmol/L glutamine in the absence of serum stimulated [H-3]thymidine incorporation 8-fold, This effect was inhibited by 60% with 8-(4-chlorophenylthio) (8-CPT)-cAMP (100 mu mol/L) + isobutyl methylxanthine (100 mu mol/L). In cells not starved of glutamine, glutamine stimulated thymidine incorporation by 3-fold, and 8-CPT-cAMP completely blocked the mitogenic effect, Inhibition of proliferation by cAMP persisted for at least 68 hours after cAMP removal, In vitro kinase assays showed that glutamine signaling requires an intact ERK (extracellular signal-related kinase) pathway in unstarved cells. In starved cells, at least one other pathway (JNK) was activated by glutamine, and the mitogenic inhibition by 8-CPT-cAMP was incomplete, Other intestinal fuels (glucose and acetate) were not mitogenic, Conclusions: Increased levels of intracellular cAMP inhibit ERKs but only partially reduce glutamine-stimulated proliferation in enterocytes adapted to low glutamine.