Die Rolle des hnRNPK-Signalkomplexes in Erk1/2-aktivierten Melanomzellen

我们研究的长期目标是分析黑色素瘤细胞的分子机制，以发现新的治疗干预手段。在我们的第一个拨款申请中，我们建议确定适配器蛋白hnRNPK在黑色素瘤细胞中的作用。我们假设hnRNPK参与了ADAM蛋白酶的激活，ADAM蛋白酶是基质金属蛋白酶的一个重要亚类。正如我们最近发表的文章所示，我们可以证实这一假设。我们发现hnRNPK和整合素相关的Paxillin蛋白作为两个ADAM蛋白酶，即TNFalpha转化酶（TACE或ADAM17）和ADAM10的激活的信号传导平台。几乎所有31个分析的黑色素瘤细胞系都显示ADAM10被激活，Paxillin也被激活（磷酸化）。因此，这两种标记的激活似乎是黑色素瘤细胞的共同特征。令人惊讶的是，多梳蛋白Eed也被确定为直接参与了ADAM蛋白酶的激活。值得注意的是，所有这些因子都是通过整合素受体激活或被整合素受体募集的。这些发现使我们得出这样的结论：激活的整合素招募并形成一个激活adam的信号复合体。基于自己和已发表的数据，我们假设肿瘤细胞中整合素的激活和表达增加导致信号蛋白如hnRNPK和Paxillin的募集，然后形成adam激活信号复合物。在这项拨款提案中，我们打算检验这一假设。此外，我们将研究最近描述的涉及Eed与nSMase2相互作用的信号机制的可能联系。

The long-term goal of our research is the analysis of molecular mechanisms in melanoma cells in order to discover new means of therapeutic intervention. In our first grant application we suggested to determine the role of the adapter protein hnRNPK in melanoma cells. We hypothesized that hnRNPK is involved in the activation of ADAM proteases, an important subclass of the matrixmetalloproteases. As demonstrated in our recent publication, we could confirm this assumption. We show that hnRNPK and the integrin-associated Paxillin protein serve as a signaling platform for the activation of two ADAM proteases, namely TNFalpha converting enzyme (TACE or ADAM17) and ADAM10. Almost all of 31 analyzed melanoma cell lines revealed activated ADAM10 and also activated (phosphorylated) Paxillin. Thus the activation of both markers seemed to be a common denominator of melanoma cells. Surprisingly also the polycomb protein Eed was identified as beeing directly involved in the activation of the ADAM proteases. Notably, all of these factors are activated through - or recruited by integrin receptors. These findings led to the conclusion that activated integrins recruit and form an ADAM-activating signaling complex. Based on own as well as published data we hypothesize that activation and increased expression of integrins in tumor cells leads to the recruitment of signaling proteins like hnRNPK and Paxillin, which then form the ADAM-activating signaling complex. In this grant proposal we intend to test this hypothesis. Furthermore we will investigate a possible link to a recently described signaling mechanism involving the interaction of Eed with nSMase2.