Bandyopadhyay Sanghamitra, Hartley Dean M, Cahill Catherine M, Lahiri Debomay K, Chattopadhyay Naibedya, Rogers Jack T
Neurochemistry Laboratory, Department of Psychiatry and Genetics and Aging Research Unit, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
J Neurosci Res. 2006 Jul;84(1):106-18. doi: 10.1002/jnr.20864.
Interleukin-1alpha (IL-1alpha) stimulates a disintegrin and metalloproteinase, ADAM-17 synthesis, consistent with activation of the soluble fragment of Amyloid Precursor Protein, APP, (sAPPalpha) in human primary astrocytes. To characterize the mechanism by which IL-1alpha promotes the non-amyloidogenic pathway of APP metabolism, we used U373 MG astrocytoma cells. IL-1alpha significantly increased levels of ADAM-10 and ADAM-17 mRNA in 16 hr. Upregulation of ADAM-17 mRNA by IL-1alpha was more pronounced despite higher basal levels of ADAM-10 mRNA. This pattern was also observed at the protein level with the upregulation of alpha-secretase. RNA interference (RNAi) of ADAM-10 and ADAM-17 inhibited IL-1alpha-stimulated sAPPalpha release and the effect was more pronounced with ADAM-17 RNAi. Concomitantly, the level of sAPPalpha was significantly increased by IL-1alpha in 48 hr; however, IL-1alpha stimulated cell-associated APP levels maximally at 6 h but the induction declined at 48 hr. IL-1alpha treatment of cells for 48 h reduced both intracellular and secreted levels of amyloid-beta, Abeta-40, and Abeta-42 peptides. Multiple MAP kinases (MAPK), including MEK/ERK, p38 kinase, PI3 kinase (PI3K) but not JNK were involved in the regulation of IL-1alpha-stimulated alpha-secretase activity and sAPPalpha release. p38 MAPK seems to be the most proximal of these MAPKs, as it was the earliest to be activated by IL-1alpha and blocking this pathway attenuated activation of IL-1alpha-induced MEK and PI3K pathways. Our data show a complex mechanism of sAPPalpha regulation by IL-1alpha that involves ADAM-10, ADAM-17 and p38 MAPK upstream of MEK and PI3K.
白细胞介素-1α（IL-1α）刺激解整合素和金属蛋白酶ADAM-17的合成，这与人类原代星形胶质细胞中淀粉样前体蛋白（APP）可溶性片段（sAPPα）的激活相一致。为了阐明IL-1α促进APP代谢非淀粉样生成途径的机制，我们使用了U373 MG星形细胞瘤细胞。IL-1α在16小时内显著增加了ADAM-10和ADAM-17的mRNA水平。尽管ADAM-10的基础mRNA水平较高，但IL-1α对ADAM-17 mRNA的上调更为明显。在蛋白质水平上，随着α-分泌酶的上调也观察到了这种模式。对ADAM-10和ADAM-17进行RNA干扰（RNAi）可抑制IL-1α刺激的sAPPα释放，且ADAM-17 RNAi的效果更显著。同时，IL-1α在48小时内显著增加了sAPPα的水平；然而，IL-1α在6小时时最大程度地刺激了细胞相关APP水平，但在48小时时诱导作用下降。用IL-1α处理细胞48小时可降低细胞内和分泌的淀粉样β蛋白（Aβ）、Aβ-40和Aβ-42肽的水平。多种丝裂原活化蛋白激酶（MAPK），包括MEK/ERK、p38激酶、磷脂酰肌醇-3激酶（PI3K），但不包括JNK参与了IL-1α刺激的α-分泌酶活性和sAPPα释放的调节。p38 MAPK似乎是这些MAPK中最上游的，因为它最早被IL-1α激活，阻断该途径可减弱IL-1α诱导的MEK和PI3K途径的激活。我们的数据显示IL-1α对sAPPα的调节机制复杂，涉及ADAM-10、ADAM-17以及位于MEK和PI3K上游的p38 MAPK。
