Bascom C C, Wolfshohl J R, Coffey R J, Madisen L, Webb N R, Purchio A R, Derynck R, Moses H L
Department of Cell Biology, Vanderbilt University, Nashville, Tennessee 37232.
Mol Cell Biol. 1989 Dec;9(12):5508-15. doi: 10.1128/mcb.9.12.5508-5515.1989.
Regulation of transforming growth factor beta 1 (TGF beta 1), TGF beta 2, and TGF beta 3 mRNAs in murine fibroblasts and keratinocytes by TGF beta 1 and TGF beta 2 was studied. In quiescent AKR-2B fibroblasts, in which TGF beta induces delayed stimulation of DNA synthesis, TGF beta 1 autoregulation of TGF beta 1 expression was observed as early as 1 h, with maximal induction (25-fold) after 6 to 12 h. Increased expression of TGF beta 1 mRNA was accompanied by increased TGF beta protein production into conditioned medium of AKR-2B cells. Neither TGF beta 2 nor TGF beta 3 mRNA, however, was significantly induced, but both were apparently down regulated at later times by TGF beta 1. Protein synthesis was not required for autoinduction of TGF beta 1 mRNA in AKR-2B cells. Nuclear run-on analyses and dactinomycin experiments indicated that autoregulation of TGF beta 1 expression is complex, involving both increased transcription and message stabilization. In contrast to TGF beta 1, TGF beta 2 treatment of quiescent AKR-2B cells increased expression of TGF beta 1, TGF beta 2, and TGF beta 3 mRNAs, but with different kinetics. Autoinduction of TGF beta 2 mRNA occurred rapidly with maximal induction at 1 to 3 h, enhanced TGF beta 3 mRNA levels were observed after 3 h, and increased expression of TGF beta 1 occurred later, with maximal mRNA levels obtained after 12 to 24 h. Nuclear run-on analyses indicated that TGF beta 2 regulation of TGF beta 2 and TGF beta 3 mRNA levels is transcriptional, while TGF beta 2 induction of TGF beta 1 expression most likely involves both transcriptional and posttranscriptional controls. In BALB/MK mouse keratinocytes, minimal autoinduction of TGF beta 1 occurred at only the 12- and 24-h time points and protein synthesis was required for this autoinduction. The results of this study provide an example in which TGF beta 1 and TGF beta 2 elicit different responses and demonstrate that expression of TGF beta 1, and TGF beta 3 are regulated differently. The physiological relevance of TGF beta 1 autoinduction in the context of wound healing is discussed.
研究了转化生长因子β1（TGFβ1）、TGFβ2和TGFβ3 mRNA在小鼠成纤维细胞和角质形成细胞中受TGFβ1和TGFβ2的调控情况。在静止的AKR - 2B成纤维细胞中，TGFβ可诱导DNA合成的延迟刺激，早在1小时就观察到TGFβ1对TGFβ1表达的自身调节，6至12小时后诱导达到最大值（25倍）。TGFβ1 mRNA表达的增加伴随着TGFβ蛋白分泌到AKR - 2B细胞的条件培养基中。然而，TGFβ2和TGFβ3 mRNA均未被显著诱导，但在后期两者均明显受到TGFβ1的下调。蛋白质合成对于AKR - 2B细胞中TGFβ1 mRNA的自身诱导不是必需的。细胞核转录分析和放线菌素实验表明，TGFβ1表达的自身调节是复杂的，涉及转录增加和信息稳定。与TGFβ1不同，用TGFβ2处理静止的AKR - 2B细胞会增加TGFβ1、TGFβ2和TGFβ3 mRNA的表达，但动力学不同。TGFβ2 mRNA的自身诱导迅速发生，在1至3小时达到最大诱导，3小时后观察到TGFβ3 mRNA水平升高，TGFβ1的表达增加较晚，在12至24小时后达到最大mRNA水平。细胞核转录分析表明，TGFβ2对TGFβ2和TGFβ3 mRNA水平的调节是转录性的，而TGFβ2诱导TGFβ1表达很可能涉及转录和转录后控制。在BALB/MK小鼠角质形成细胞中，仅在12小时和24小时时间点发生TGFβ1的最小自身诱导，并且这种自身诱导需要蛋白质合成。本研究结果提供了一个例子，其中TGFβ1和TGFβ2引发不同的反应，并证明TGFβ1和TGFβ3的表达受到不同的调节。讨论了TGFβ1自身诱导在伤口愈合背景下的生理相关性。
