Rosé S D, Byers D M, Morash S C, Fedoroff S, Cook H W
Atlantic Research Centre, Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada.
J Neurosci Res. 1996 May 1;44(3):235-42. doi: 10.1002/(SICI)1097-4547(19960501)44:3<235::AID-JNR4>3.0.CO;2-H.
Microglia rapidly respond to lipoplysaccharide (LPS) by transformation from resting to active states and secretion of several neuro- and immuno-regulators including tumour necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), and interleukin 6 (IL-6). With longer LPS treatment, microglia are converted to reactive or phagocytic states with characteristics similar to macrophages in inflammation and injury processes. We have investigated LPS-mediated changes in two myristoylated substrates of protein kinase C (PKC): MARCKS (myristoylated alaninerich C kinase substrate) and MRP (MARCKS-related protein). Within 6 hours of addition, LPS induced a twofold increase in [3H]myristoylated and immunoreactive MARCKS protein and a sevenfold increase in MRP. The differential effect of LPS on expression of MRP vs. MARCKS was even more dramatic at the level of transcription: S1 nuclease protection assays revealed a 40-fold increase in MRP mRNA levels (maximum at 4-6 hours), whereas a threefold increase was observed for MARCKS. TNF alpha and colony-stimulating factor 1 (CSF-1), two cytokines which are induced by LPS, did not reproduce the observed effect of LPS on MARCKS and MRP gene transcription. CSF-1 also induced differential transcription of MRP, but of lower magnitude (threefold) and more sustained than by LPS. Accordingly, these two substrates for PKC are differentially up-regulated by LPS, apparently independent of TNF alpha or CSF-1.
小胶质细胞通过从静止状态转变为活跃状态以及分泌多种神经和免疫调节因子（包括肿瘤坏死因子α（TNF-α）、白细胞介素1β（IL-1β）和白细胞介素6（IL-6））对脂多糖（LPS）迅速做出反应。随着LPS处理时间延长，小胶质细胞转变为反应性或吞噬状态，其特征类似于炎症和损伤过程中的巨噬细胞。我们研究了LPS介导的蛋白激酶C（PKC）的两种豆蔻酰化底物的变化：MARCKS（豆蔻酰化富含丙氨酸的C激酶底物）和MRP（MARCKS相关蛋白）。添加LPS后6小时内，LPS使[3H]豆蔻酰化和免疫反应性MARCKS蛋白增加了两倍，使MRP增加了七倍。在转录水平上，LPS对MRP与MARCKS表达的差异作用更为显著：S1核酸酶保护试验显示MRP mRNA水平增加了40倍（在4 - 6小时达到最大值），而MARCKS仅增加了三倍。LPS诱导产生的两种细胞因子，即TNFα和集落刺激因子1（CSF-1），并未重现LPS对MARCKS和MRP基因转录的观察效果。CSF-1也诱导了MRP的差异转录，但幅度较小（三倍）且比LPS诱导的更持久。因此，PKC的这两种底物被LPS差异上调，显然独立于TNFα或CSF-1。
