Kuiper J, Zijlstra F J, Kamps J A, Van Berkel T J
Division of Biopharmaceutics, University of Leiden, The Netherlands.
Biochem J. 1989 Aug 15;262(1):195-201. doi: 10.1042/bj2620195.
The major eicosanoid produced within the rat liver, prostaglandin (PG) D2, wa studied for its ability to interact with the various liver cell types. It appeared that PGD2 bound specifically to parenchymal liver cells, whereas the binding of PGD2 to Kupffer and endothelial liver cells was quantitatively unimportant. Maximally 700 pg of PGD2/mg of parenchymal-cell protein could be bound by a high-affinity site (1 x 10(6) PGD2-binding sites/cell). The recognition site for PGD2 is probably a protein because trypsin treatment of the cells virtually abolished the high-affinity binding. High-affinity binding of PGD2 was a prerequisite for the induction of a metabolic effect in isolated parenchymal liver cells, i.e. the induction of glycogenolysis. High-affinity binding of PGD2 by parenchymal cells was coupled to the conversion of PGD2 into three metabolites, whereas no conversion of PGD2 by Kupffer and endothelial liver cells was noticed. The temperature-sensitivity of the conversion of PGD2 was consistent with a conversion of PGD2 on or in the vicinity of the cell membrane. One of the PGD2 metabolites could be identified as 9 alpha, 11 beta-PGF2. It can be calculated that the conversion rate of PGD2 by parenchymal liver cells exceeds the production rate of PGD2 by Kupffer plus endothelial liver cells, indicating that PGD2 is meant to exert its activity within the liver. The present finding that PGD2 formed by the non-parenchymal liver cells is recognized by a specific receptor on parenchymal liver cells and that binding, conversion and metabolic effect of PGD2 are interlinked by this receptor provides further support for the specific role of PGD2 in the intercellular communication in the liver.
对大鼠肝脏中产生的主要类二十烷酸——前列腺素（PG）D2与各种肝细胞类型相互作用的能力进行了研究。结果显示，PGD2特异性结合肝实质细胞，而PGD2与库普弗细胞和肝内皮细胞的结合在数量上并不重要。一个高亲和力位点（每个细胞1×10⁶个PGD2结合位点）最多可结合700 pg的PGD2/毫克肝实质细胞蛋白。PGD2的识别位点可能是一种蛋白质，因为用胰蛋白酶处理细胞实际上消除了高亲和力结合。PGD2的高亲和力结合是在分离的肝实质细胞中诱导代谢效应（即诱导糖原分解）的先决条件。肝实质细胞对PGD2的高亲和力结合与PGD2转化为三种代谢产物有关，而未观察到库普弗细胞和肝内皮细胞对PGD2的转化。PGD2转化的温度敏感性与PGD2在细胞膜上或其附近的转化一致。其中一种PGD2代谢产物可鉴定为9α,11β - PGF2。可以计算出，肝实质细胞对PGD2的转化率超过了库普弗细胞和肝内皮细胞产生PGD2的速率，这表明PGD2旨在在肝脏内发挥其活性。目前的研究发现，非肝实质细胞形成的PGD2可被肝实质细胞上的特异性受体识别，并且PGD2的结合、转化和代谢效应通过该受体相互联系，这进一步支持了PGD2在肝脏细胞间通讯中的特定作用。
