Shapiro S D, Doyle G A, Ley T J, Parks W C, Welgus H G
Department of Medicine, Jewish Hospital Washington University Medical Center, St. Louis, Missouri 63110.
Biochemistry. 1993 Apr 27;32(16):4286-92. doi: 10.1021/bi00067a018.
We have used the human promonocyte-like U937 cell line as a model to study the regulation of interstitial collagenase and tissue inhibitor of metalloproteinases (TIMP) during mononuclear phagocyte development. Our results show that differentiation of U937 cells with exposure to 12-O-tetradecanoylphorbol 13-acetate (TPA) induces a temporally delayed (16-24 h) but marked increase in the biosynthesis and secretion of interstitial collagenase and TIMP. Similarly, steady-state mRNA levels for both proteins rose dramatically during the period of exposure, but again after considerable time delay (12-16 h). For interstitial collagenase, induction was transcriptionally regulated as demonstrated by nuclear run-on experiments, and required the synthesis of proteins as indicated by cycloheximide treatment. However, transcriptional activation of collagenase was never observed prior to 10-12 h; since c-fos is rapidly induced in U937 cells and largely disappears by 2 h (Mitchell et al., 1985), our data strongly suggest that collagenase induction in this system cannot be explained simply or entirely by an AP-1-dependent mechanism. Although TIMP steady-state mRNA levels also increased substantially with cellular differentiation, no transcription was detected by run-on experiments. However, TPA exposure markedly prolonged the half-life of TIMP mRNA from 4 h to > 20 h. While cycloheximide treatment completely blocked TPA-mediated induction of collagenase mRNA, it only marginally interfered with simultaneously induced TIMP mRNA levels. Our results demonstrate that differentiation of U937 monocytic cells is accompanied by markedly enhanced production of both interstitial collagenase and TIMP. However, there are multiple, and perhaps differing, molecular mechanisms regulating these responses.
我们使用人原单核细胞样U937细胞系作为模型，研究单核吞噬细胞发育过程中间质胶原酶和金属蛋白酶组织抑制剂（TIMP）的调控。我们的结果表明，用12 - O - 十四酰佛波醇 - 13 - 乙酸酯（TPA）处理U937细胞诱导其分化，可导致间质胶原酶和TIMP的生物合成及分泌出现暂时延迟（16 - 24小时）但显著增加。同样，两种蛋白的稳态mRNA水平在处理期间大幅上升，但同样有相当长的延迟时间（12 - 16小时）。对于间质胶原酶，核转录实验表明其诱导是由转录调控的，环己酰亚胺处理表明其诱导需要蛋白质合成。然而，在10 - 12小时之前从未观察到胶原酶的转录激活；由于c - fos在U937细胞中快速诱导并在2小时时基本消失（Mitchell等人，1985），我们的数据强烈表明，该系统中胶原酶的诱导不能简单或完全用AP - 1依赖机制来解释。虽然TIMP的稳态mRNA水平也随着细胞分化而大幅增加，但核转录实验未检测到转录。然而，TPA处理显著延长了TIMP mRNA的半衰期，从4小时延长至> 20小时。虽然环己酰亚胺处理完全阻断了TPA介导的胶原酶mRNA诱导，但仅轻微干扰了同时诱导的TIMP mRNA水平。我们的结果表明，U937单核细胞的分化伴随着间质胶原酶和TIMP的产生显著增强。然而，调节这些反应存在多种且可能不同的分子机制。
