Elucidation of the in vivo function of the Ras/Rap effector phospholipase Cε

(1)与野生型小鼠相比，磷脂酶Cε(PLCε)基因敲除小鼠的皮肤炎症反应明显减轻，同时伴有水肿和白细胞渗出。同时，白介素1α等促炎细胞因子在ε基因敲除小鼠培养的角质形成细胞和真皮成纤维细胞中的表达减少。我们还发现，PLCε在TPA下游被激活，这是通过TPA的直接靶标RasGRP3介导的。此外，通过使用不同的炎症诱导小鼠模型系统，例如使用葡聚糖硫酸盐的溃疡性结肠炎模型，使用二硝基氟苯作为半抗原的接触性皮炎模型，以及紫外线辐射诱导的皮炎，我们观察到炎症反应的严重减少。这些结果表明，PLCε通过诱导促炎细胞因子在炎症反应中发挥重要而普遍的作用。…更多(2)与野生型背景相比，在PLCε基因敲除背景下，观察到携带抗癌基因apc功能缺失突变的Min小鼠的新生肠道肿瘤形成和随后的恶性进展显著减少。综上所述，我们之前的研究结果表明，在两阶段皮肤化学致癌模型中，PLCε基因敲除小鼠对肿瘤的形成和随后的恶性进展具有很高的抵抗力，这些结果非常有趣，因为它们表明炎症和癌症的发生之间存在密切的联系。(3)利用Cre-ε重组系统，我们获得了在皮肤角质形成细胞中高表达PLCε的转基因小鼠。有趣的是，这些小鼠表现出强烈的皮肤炎症，伴随着显著的角化过度和血管生成增加。1-3中的结果提示PLCε可能成为开发抗癌药物或抗炎药物的良好分子靶点。(4)我们分析了PLCε基因敲除小鼠在胚胎期出现半月瓣膜发育缺陷的分子机制。我们发现PLCε受肝素结合的表皮生长因子样生长因子受体下游信号的调控，并通过抑制骨形态发生蛋白受体刺激诱导的Smad1/5/8的磷酸化来抑制瓣膜前体细胞的增殖。较少

(1) The skin of phospholipase Cε (PLCε) knockout mice exhibited great reduction in inflammatory responses accompanied by edema and in leukocyte infiltration induced by phorbor ester (TPA) treatment compared to that of wild-type mice. Concomitantly, reduced expression of proinflammatory cytokines such as interleukin-1α was observed in keratinocytes and dermal fibroblasts cultured from PLCε knockout mice upon TPA treatment. We also showed that PLCε is activated downstream of TPA, which is mediated by Rap1 activation via RasGRP3, a direct target of TPA. Furthermore, by employing various inflammation-inducing mouse model systems, such as an ulcerative colitis model using dextran sulfate, a contact dermatitis model using dinitrofluorobenzene as a hapten, and an ultraviolet radiation-induced dermatitis, we observed severe decrease in inflammatory responses. These results imply that PLCε plays a crucial and general role in inflammatory responses through induction of proinflammatory cytokines. … More (2) Great reduction in de novo intestinal tumor formation and subsequent malignant progression of Min mice, which carry a loss-of-function mutation in the anti-oncogene APC, was observed on the PLCε-knockout background compared to wild-type background. Taken together with our previous result showing that PLCε knockout mice are highly resistant to tumor formation and subsequent malignant progression in the two stage skin chemical carcinogenesis model, these results are quite interesting because they suggest a close link between inflammation and cancer promotion.(3) We generated PLCε transgenic mice, which overexpress PLCε specifically in skin keratinocytes, by using the Cre-loxP recombination system. Interestingly, these mice exhibited strong skin inflammation accompanied by prominent hyperkeratosis and elevated angiogenesis. The results described in 1-3 suggest that PLCε may make a good molecular target for the development of cancer-preventing drugs or anti-inflammatory drugs.(4) We analyzed molecular mechanisms whereby PLCε knockout mice exhibit defective semilunar valvulogenesis during embryonic period. We showed that PLCε is regulated by downstream signaling from heparin-binding epidermal growth factor-like growth factor (HB-EGF) receptor and inhibits proliferation of valvular precursor cells through inhibition of Smad1/5/8 phosphorylation induced by the bone morphogenetic protein (BMP) receptor stimulation. Less