Trafficking of the EGF receptor to the nucleus: Mechanisms and Effects

描述（由申请人提供）：肝脏显示出独特的生长和再生能力。例如，在三分之二的肝脏被切除后，完全的肝脏再生会在几天到几周内发生。慢性肝细胞损伤可导致肝脏再生调节功能受损，从而导致肝细胞癌，这是世界上最常见的恶性肿瘤之一。亲本授权的假设是，HGF通过c-met，通过诱导肝细胞核内insp3介导的Ca2+信号来调节肝脏的生长。这项FIRCA应用将研究这是否是受体酪氨酸激酶（rtk）在一系列组织中的更普遍的作用机制。具体来说，这个FIRCA应用的假设是表皮生长因子受体（EGFR），像c-met一样，通过诱导细胞核内insp3介导的Ca2+信号来调节细胞生长，并且EGFR的这种作用介导了常见恶性肿瘤的细胞增殖。这一假设将通过以下具体目的进行检验：1。在常见的恶性肿瘤中，EGFR是否以及如何到达细胞核将被确定。我们将测试小泡中的egfr亚群是否会运输到细胞核。细胞内受体的运动将通过细胞分离研究来监测。在肝细胞中发现的途径将在来自乳腺癌、肺癌、前列腺癌和结肠癌的细胞中进行测试。2. EGF是否以及如何增加细胞核中的Ca2+将被确定。靶向的InsP3缓冲液将用于确定EGF是否像HGF一样特异性诱导细胞核内的InsP3形成。RNA干扰技术将用于比较EGF和HGF激活的PLC亚型，并确定这些PLC亚型在细胞类型之间是否存在差异。3. 核Ca2+信号在egf诱导的细胞生长中的作用将被确定。我们将确定egf诱导的细胞增殖是否通过阻断(a) EGFR向细胞核的移动，(b) egf诱导的细胞核内Ca2+信号的形成，或(c)细胞核内Ca2+依赖性蛋白的激活，如CaMKII，而被破坏。这些研究将揭示生长因子及其相应的受体酪氨酸激酶如何控制完整细胞中的核Ca2+，并确定其在调节肿瘤生长中可能发挥的独特作用。这项研究将主要在巴西的UFMG进行，与davidson Gomes合作，作为NIH P01 DK57751项目1的延伸。

DESCRIPTION (provided by applicant): The liver displays a unique ability to grow and regenerate. For example, complete hepatic regeneration occurs within days to weeks after two-thirds of the liver has been resected. Chronic hepatocellular damage can lead to impaired regulation of liver regeneration, which results in hepatocellular carcinoma, one of the most common malignancies in the world. The hypothesis of the parent grant is that HGF, via c-met, regulates growth in the liver by inducing InsP3-mediated Ca2+ signals within the nucleus of hepatocytes. This FIRCA application would investigate whether this is a more general mechanism of action of receptor tyrosine kinases (RTKs) across a range of tissues. Specifically, the hypothesis of this FIRCA application is that the Epidermal Growth Factor receptor (EGFR), like c-met, regulates cell growth by inducing InsP3-mediated Ca2+ signals within the nucleus, and that this action of EGFR mediates cell proliferation in common malignancies. This hypothesis will be tested through the following specific aims: 1. whether and how the EGFR reaches the nucleus in common malignancies will be determined. We will test whether a sub-population of EGFRs in caveolae traffic to the nucleus. Intracellular movement of the receptor will be monitored by as well as by cell fractionation studies. Pathways identified in liver cells will be tested in cells derived from breast, lung, prostate, and colon cancers. 2. Whether and how EGF increases Ca2+ in the nucleus will be determined. Targeted InsP3 buffers will be used to determine whether EGF, like HGF, specifically induces InsP3 formation within the nucleus. RNA interference techniques will be used to compare PLC isoforms activated by EGF and HGF, and to determine whether these PLC isoforms vary among cell types. 3. The role of nuclear Ca2+ signals in EGF-induced cell growth will be determined. We will determine whether EGF-induced cell proliferation is disrupted by blocking either (a) movement of EGFR to the nucleus, (b) EGF-induced formation Ca2+ signals in the nucleus, or (c) activation of Ca2+-dependent proteins within the nucleus, such as CaMKII. These studies will reveal how growth factors and their corresponding receptor tyrosine kinases control nuclear Ca2+ in intact cells, and identify the distinct role this may play in regulating tumor growth. This research will be performed primarily at UFMG in Brazil in collaboration with Dawidson Gomes as an extension of Project 1 of NIH P01 DK57751. PUBLIC HEALTH RELEVANCE: Growth of cells within the liver and other organs is regulated by growth factors and their receptors, known as receptor tyrosine kinases. These studies will reveal how growth factors and their corresponding receptor tyrosine kinases control signaling within the cell nucleus, and identify the distinct role this signaling pathway may play in the abnormal growth that occurs in a wide variety of tumors.