Shimada A, Ota Y, Sugiyama Y, Sato S, Kume K, Shimizu T, Inoue S
Basic Research Laboratory, Kanebo Ltd, Kanagawa, Odawara, Japan.
J Invest Dermatol. 1998 Jun;110(6):889-93. doi: 10.1046/j.1523-1747.1998.00202.x.
Platelet-activating factor (PAF) is a potent lipid mediator that exhibits versatile biologic activities in many diverse systems by binding to a specific cell-surface receptor (PAFR). Although the production of PAF in cultured keratinocytes and fibroblasts has been reported, physiologic roles of this mediator in skin remain unclear. In this study, we examined in situ expression of PAFR gene in rat skin and the effects of PAF on the proliferation and differentiation of cultured human keratinocytes. In rat epidermis, PAFR mRNA expression was found from the basal cells to the granular cells, and strong signals were seen in the stratum spinosum. In cultured human keratinocytes, a 3.8 kb PAFR mRNA expression was demonstrated by northern blotting, and two distinct type transcripts driven by different promoters were detected by reverse transcriptase polymerase chain reaction analysis. Addition of PAF (30-100 nM) to cultured keratinocytes during a growth phase inhibited the proliferation. This effect was receptor dependent, because the inhibition was completely blocked by a PAFR antagonist, WEB 2086 (100 nM). On the other hand, whereas PAF (30-100 nM) alone did not affect the cornified envelope formation during the process of keratinocyte differentiation, WEB 2086 (30-300 nM) accelerated it in a concentration-dependent manner. Addition of PAF (100 nM) reversed the effect of WEB 2086, suggesting that WEB 2086 induced cornification by inhibiting PAF endogeneously produced by keratinocytes in an autocrine manner. Thus, we propose that PAF is an intrinsic regulator of keratinocyte during proliferation and differentiation.
血小板活化因子（PAF）是一种强效脂质介质，通过与特定细胞表面受体（PAFR）结合，在许多不同系统中展现出多种生物学活性。尽管已有报道称培养的角质形成细胞和成纤维细胞可产生PAF，但这种介质在皮肤中的生理作用仍不清楚。在本研究中，我们检测了大鼠皮肤中PAFR基因的原位表达以及PAF对培养的人角质形成细胞增殖和分化的影响。在大鼠表皮中，从基底细胞到颗粒细胞均发现有PAFR mRNA表达，在棘层可见强信号。在培养的人角质形成细胞中，Northern印迹法证实有3.8 kb的PAFR mRNA表达，逆转录聚合酶链反应分析检测到由不同启动子驱动的两种不同类型的转录本。在生长阶段向培养的角质形成细胞中添加PAF（30 - 100 nM）可抑制其增殖。这种作用是受体依赖性的，因为PAFR拮抗剂WEB 2086（100 nM）可完全阻断这种抑制作用。另一方面，虽然单独的PAF（30 - 100 nM）在角质形成细胞分化过程中不影响角质包膜的形成，但WEB 2086（30 - 300 nM）以浓度依赖性方式加速了其形成。添加PAF（100 nM）可逆转WEB 2086的作用，这表明WEB 2086通过以自分泌方式抑制角质形成细胞内源性产生的PAF来诱导角质化。因此，我们认为PAF是角质形成细胞增殖和分化过程中的一种内在调节因子。
