Synergistic effects of retinoic acid and IL-1beta on expression of the bone-type alkaline phsphatase and retinoid receptors in small intestinal epithelial cells.

去年，我们报道了同时加入视黄酸（RA）和IL-1 β诱导大鼠肠上皮IEC-6细胞系中的多种蛋白质以及肝/骨/肾碱性磷酸酶（L/B/K ALP）。在随后的研究中，我们发现RA和IL-1 β上调的L/B/K ALP具有骨型前导序列，而非肝型前导序列。凝胶迁移率变动分析表明，结合活性协同刺激RA和IL-1 β的同时处理。我们进一步研究了维甲酸受体和IL-1受体在这些协同作用中的参与。同时用RA和IL-1 β处理IEC-6细胞后，可见不同程度的视黄酸受体（RARs）和类维生素A X受体（RXRs）。RA和IL-1 β协同表达RAR α和β以及RXR α和β，而同时处理不会改变RAR γ和RXR γ的表达。在这些受体中，RAR β mRNA表达的增强最为显著。有趣的是，IL-1 β增加了RAR β的mRNA水平，但RA本身没有。相反，即使在同时处理后，IL-1受体I型的mRNA水平也没有改变。提示RA和IL-1 β协同作用可能与RA受体尤其是RAR β表达上调有关。在另一项实验中，还发现RA和IL-1 β同时处理可协同增加人腺癌Caco-2细胞中的组织蛋白酶活性。因此，我们将提供证据表明，IL-1 β可能调节肠上皮细胞的蛋白质合成。

Last year, we reported that simultaneous addition of retinoic acid (RA) and IL-1beta induced a number of proteins as well as liver/bone/kidney alkaline phosphatase (L/B/K ALP) in rat intestinal epithelial IEC-6 cell line. In the subsequent studies, we found that the L/B/K ALP up-regulated with RA and IL-1beta had the bone-type leader sequence, but not liver-type one. Gel mobility shift assay for the putative RXRE showed that the binding activity was synergistically stimulated by the simultaneous treatment with RA and IL-1beta. We further studied the involvement of retinoid receptors and IL-1 receptor in these synergistic effects. The distinct of retinoic acid receptors (RARs) and retinoid X receptors (RXRs) were observed in IEC-6 cells after simultaneous treatment with RA and IL-1beta. RARs alpha and beta, and RXRs alpha and beta were synergistically expressed by RA and IL-1beta, while the expression of RARgamma and RXRgamma were not changed by the simultaneous treatment. The enhancement of RARbeta mRNA expression was the most remarkable among these receptors. It was of interest that IL-1beta increased the mRNA level of RARbeta, but RA itself did not. In contrast, the mRNA level of IL-1 receptor type-I were not changed even after the simultaneous treatment. These finding suggested that up-regulation of retinoid receptors, especially RARbeta, may participated in the synergistic effects of RA and IL-1beta. In a separate experiment, it was also found that simultaneous treatment with RA and IL-1beta synergisticaly increased cathepsin activities in human adenocarcinoma Caco-2 cells. Thus, we will provide the evidence suggesting that IL-1beta may regulate the protein synthesis in intestinal epithelial cells.