Lyons-Giordano B, Pratta M A, Galbraith W, Davis G L, Arner E C
Department of Dermatology, University of Pennsylvania, Philadelphia 19104.
Exp Cell Res. 1993 May;206(1):58-62. doi: 10.1006/excr.1993.1120.
Interleukin-1 beta (IL-1) increases the synthesis of prostaglandins as well as the expression of synovial fluid phospholipase A2 (PLA2) mRNA and activity by chondrocytes. In order to examine the potential involvement of cyclooxygenase in the induction of prostaglandins by IL-1, the effect of IL-1 on rabbit articular chondrocyte expression of cyclooxygenase enzymes was investigated. By Northern analyses, mRNA for cyclooxygenase-2 (COX-2) was found to be constitutively expressed, and its expression was increased in cultures treated for 24 h with IL-1 (100 ng/ml). Cyclooxygenase-1 mRNA was not detected in control or IL-1-treated cultures. IL-1 caused a concentration-dependent increase in steady-state levels of COX-2 message as assessed by slot-blot analyses. Half-maximal induction of the COX-2 message levels was estimated to require 1.2 ng/ml IL-1. In duplicate slot blots probed with a cDNA for synovial fluid PLA2, half-maximal induction of PLA2 mRNA was estimated to require 0.15 ng/ml IL-1, approximately 10-fold less IL-1 than required for COX-2. In addition, maximal increase in COX-2 message levels was only 3-fold as compared with a 13-fold induction of PLA2. No change in message levels for the intracellular protein, actin, was found between control and experimental cultures. Cycloheximide enhanced COX-2 transcript levels, but did not modulate IL-1 induction of COX-2. Actinomycin D did not inhibit IL-1 augmentation of COX-2 mRNA levels; whereas, induction of PLA2 mRNA levels was completely inhibited, implicating transcriptional mechanisms in the induction of PLA2 but not COX-2 mRNA. These data demonstrate that chondrocyte expression of COX-2 and synovial fluid PLA2 are differentially modulated by IL-1.
白细胞介素 -1β（IL -1）可增加前列腺素的合成，以及软骨细胞中滑液磷脂酶A2（PLA2）mRNA的表达和活性。为了研究环氧化酶在IL -1诱导前列腺素过程中的潜在作用，研究了IL -1对兔关节软骨细胞中环氧化酶表达的影响。通过Northern分析发现，环氧化酶 -2（COX -2）的mRNA组成性表达，在用IL -1（100 ng/ml）处理24小时的培养物中其表达增加。在对照或IL -1处理的培养物中未检测到环氧化酶 -1 mRNA。通过狭缝印迹分析评估，IL -1导致COX -2信息的稳态水平呈浓度依赖性增加。估计COX -2信息水平的半最大诱导需要1.2 ng/ml IL -1。在用滑液PLA2的cDNA探测的重复狭缝印迹中，PLA2 mRNA的半最大诱导估计需要0.15 ng/ml IL -1，比COX -2所需的IL -1少约10倍。此外，与PLA2的13倍诱导相比，COX -2信息水平的最大增加仅为3倍。在对照和实验培养物之间未发现细胞内蛋白质肌动蛋白的信息水平有变化。放线菌酮增强了COX -2转录水平，但未调节IL -1对COX -2的诱导。放线菌素D不抑制IL -1对COX -2 mRNA水平的增强；而PLA2 mRNA水平的诱导被完全抑制，这表明PLA2 mRNA的诱导涉及转录机制，而COX -2 mRNA的诱导则不然。这些数据表明，IL -1对软骨细胞中COX -2和滑液PLA2的表达有不同的调节作用。
