Singleton Kristen D, Wischmeyer Paul E
Department of Anesthesiology, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
JPEN J Parenter Enteral Nutr. 2008 Jul-Aug;32(4):371-6. doi: 10.1177/0148607108320661.
Glutamine (GLN) improves outcome in experimental and clinical states of illness and injury. The authors hypothesized GLN-mediated enhancement of O-glycosylation and subsequent phosphorylation of key transcription factors in the HSP70 pathway would lead to increased HSP70 expression following experimental sepsis.
Mice underwent cecal ligation and puncture (CLP)-induced sepsis and were treated with GLN (0.75 g/kg) or a saline placebo 30 minutes after CLP. A separate group of mice was treated with mithramycin, an Sp1 inhibitor. Lung tissue was harvested at 1, 2, 6, and 24 hours after CLP and was analyzed for HSF-1 and Sp1 O-GlcNAc modification, alpha-p-threonine modification, and HSP70.
GLN increased O-GlcNAc modification of HSF-1 and Sp1 at 1 and 2 hours after sepsis (P < .001 vs saline). Samples immunoprecipitated for Sp1 and probed for subsequent phosphorylation showed a significant increase in nuclear alpha-p-threonine-modified Sp1 at 2 and 6 hours after sepsis (P < .001 vs saline). GLN increased phosphorylated nuclear HSF-1 at 1 and 2 hours after CLP (P < .001). Finally, GLN treatment increased HSP70 4-fold (P < .01), but when treated with mithramycin, this increase was attenuated at 2, 6, and 24 hours (P < .001 vs no mithramycin treatment).
These results indicate that GLN induces HSF-1 and Sp1, which is known to lead to their nuclear translocation. The molecular mechanism of GLN-mediated HSP70 expression appears to be dependent on O-GlcNAc pathway activation and subsequent O-glycosylation and phosphorylation of key transcription factors required for HSP70 induction.
谷氨酰胺（GLN）可改善实验性及临床疾病和损伤状态下的预后。作者推测，GLN介导的O-糖基化增强以及热休克蛋白70（HSP70）通路中关键转录因子的后续磷酸化，会导致实验性脓毒症后HSP70表达增加。
小鼠接受盲肠结扎和穿刺（CLP）诱导的脓毒症，并在CLP后30分钟用GLN（0.75 g/kg）或生理盐水安慰剂治疗。另一组小鼠用放线菌素D（一种Sp1抑制剂）治疗。在CLP后1、2、6和24小时采集肺组织，分析热休克因子1（HSF-1）和Sp1的O-连接N-乙酰葡糖胺（O-GlcNAc）修饰、α-磷酸苏氨酸修饰及HSP70。
脓毒症后1小时和2小时，GLN增加了HSF-1和Sp1的O-GlcNAc修饰（与生理盐水组相比，P < 0.001）。针对Sp1进行免疫沉淀并检测后续磷酸化的样本显示，脓毒症后2小时和6小时，核内α-磷酸苏氨酸修饰的Sp1显著增加（与生理盐水组相比，P < 0.001）。CLP后1小时和2小时，GLN增加了磷酸化核内HSF-1（P < 0.001）。最后，GLN治疗使HSP70增加了4倍（P < 0.01），但用放线菌素D治疗后，在2、6和24小时这种增加减弱（与未用放线菌素D治疗相比，P < 0.001）。
这些结果表明，GLN诱导HSF-1和Sp1，已知这会导致它们的核转位。GLN介导的HSP70表达的分子机制似乎依赖于O-GlcNAc通路激活以及HSP70诱导所需关键转录因子的后续O-糖基化和磷酸化。
