Angelis Dimitrios, Fontánez Nieves Tania D, Delivoria-Papadopoulos Maria
Division of Neonatology, Department of Pediatrics, Texas Tech University Health Sciences Center, Odessa, TX, 79763, USA.
Department of Pediatrics, Drexel University and St. Christopher's Hospital for Children, Philadelphia, PA, USA.
Neurochem Res. 2015 Nov;40(11):2270-9. doi: 10.1007/s11064-015-1717-8. Epub 2015 Sep 5.
The Src family kinases are a family of intracellular, non-receptor tyrosine kinases that are involved in a variety of cellular functions including the regulation of inflammation and apoptosis after brain hypoxia. Caspase-1 (C1) activates IL-1β through the formation of complex structures, the inflammasomes, while caspase-8 (C8) is part of the extrinsic apoptotic pathway. C8 has been found to directly activate the production of IL-1β. Previously, we observed that C1 and IL-1β are increased in the acute phase after hypoxia in the brain of piglets, but they follow a different pattern long term, with C1 remaining activated throughout the period of observation, while IL-1β returning to baseline at 15 days. Src kinase inhibition ameliorated the activation of C1 and IL-1β early, but did not appear to have any effect long term. Prompted by these findings, we assessed the changes that occur over time (1 h and 15 days) in C1 and C8 activities after brain hypoxia as well as the effect of pretreatment with a Src kinase inhibitor, PP2 on these biochemical markers. Enzymatic activities were determined by spectrophotometry with measurements of C1 and C8 in each cytosolic brain sample (N = 4 in each group). We found that C1 and C8 activities increase in the acute phase following hypoxia in the brain of newborn piglets, with C8 relatively more than C1 (C8/C1 ratio increased from 2:1 as baseline to 3:1 in hypoxia). Fifteen days after hypoxia C8/C1 ratio decreased to about 1:1. In piglets that were pretreated with a Src kinase selective inhibitor (PP2) and then subjected to hypoxia, the C8/C1 ratio early increase was not observed. Immediately after hypoxia C8 and C1 follow a similar pattern of increase while long term this appears to dissociate. We propose that following this experimental methodology, the previously observed IL-1β production after hypoxia might be associated with C8 rather than C1 and that Src kinase is involved in the above process.
Src家族激酶是一类细胞内非受体酪氨酸激酶,参与多种细胞功能,包括脑缺氧后炎症和细胞凋亡的调节。半胱天冬酶-1(C1)通过形成复合结构即炎性小体来激活白细胞介素-1β(IL-1β),而半胱天冬酶-8(C8)是外源性细胞凋亡途径的一部分。已发现C8可直接激活IL-1β的产生。此前,我们观察到仔猪脑缺氧急性期C1和IL-1β增加,但长期来看它们呈现不同模式,C1在整个观察期内持续激活,而IL-1β在15天时恢复到基线水平。Src激酶抑制早期改善了C1和IL-1β的激活,但长期来看似乎没有任何效果。受这些发现的启发,我们评估了脑缺氧后C1和C8活性随时间(1小时和15天)的变化,以及用Src激酶抑制剂PP2预处理对这些生化标志物的影响。通过分光光度法测定酶活性,测量每个脑细胞质样品中的C1和C8(每组n = 4)。我们发现新生仔猪脑缺氧急性期C1和C8活性增加,C8相对C1增加更多(C8/C1比值从基线时的2:1增加到缺氧时的3:1)。缺氧15天后,C8/C1比值降至约1:1。在用Src激酶选择性抑制剂(PP2)预处理然后进行缺氧的仔猪中,未观察到C8/C1比值早期增加。缺氧后立即,C8和C1呈现相似的增加模式,但长期来看似乎分离。我们提出,按照这种实验方法,先前观察到的缺氧后IL-1β产生可能与C8而非C1相关,并且Src激酶参与上述过程。