EMMPRIN: from biology to molecular mechanism

描述（由申请人提供）：细胞外基质金属蛋白酶诱导剂（EMMPRIN）在多种癌症和炎症性疾病中高表达，刺激基质金属蛋白酶（MMPs）和促炎细胞因子的分泌。EMMPRIN是作为跨膜蛋白存在的独特蛋白质子集之一，但由细胞以多种未表征的形式释放。这些细胞外形式已经与至少六种癌症有关，并已被证明在癌症进展过程中有助于形成积极的反馈循环。因此，确定EMMPRIN的特定细胞外形式，描述每种形式如何促进疾病进展，并确定它们的细胞靶标将大大有助于我们对癌症和炎症的理解。我们采用综合方法，通过结合生物学、生化和原子分辨率研究，充分表征EMMPRIN及其在疾病进展中的作用。我们的生物学研究已经确定了人类血液中几种细胞外形式的EMMPRIN和癌细胞释放的EMMPRIN，这些形式分泌的特定MMPs/细胞因子将在这里充分表征（目的1）。为此，我们开发了重组表达系统，可以产生所有必需的蛋白质。然后，我们将利用我们的重组蛋白确定这些EMMPRIN形式的细胞靶标并表征它们的相互作用（目标2）。最后，我们已经开始解决x射线晶体结构和表征视网膜特异性EMMPRIN异构体的溶液行为，该异构体有助于视网膜母细胞瘤，在这里，我们将从生物物理和生物学上表征这种异构体（目标3）。由于EMMPRIN过表达会导致参与多种疾病进展的整个蛋白家族的失调，我们结合生物学和生物物理学的方法将分别在生物学和分子水平上充分表征细胞外EMMPRIN。公共卫生相关性：细胞外基质金属蛋白酶诱导剂（EMMPRIN）调节许多信号通路，这些信号通路在数十种癌症和炎症性疾病中被解除调控，其中包括刺激基质金属蛋白酶和细胞因子的分泌。虽然EMMPRIN最初被确定为细胞跨膜蛋白，但最近发现细胞外EMMPRIN在疾病进展中也起着重要作用。然而，关于细胞外EMMPRIN及其相互作用知之甚少。我们已经在人体血液中发现了几种高水平的细胞外EMMPRIN形式，我们已经发现其中一种非常活跃。我们还建立了重组表达系统来产生所有这些细胞外EMMPRIN形式，这将使我们能够表征它们在这里的活动，我们已经开始了对视网膜特异性EMMPRIN形式的研究，该形式有助于视网膜母细胞瘤。拟议的研究重点是充分表征细胞外EMMPRIN形式对MMP/细胞因子分泌和靶标相互作用的刺激活性，为疾病进展和新治疗靶点的鉴定提供见解。

DESCRIPTION (provided by applicant): The Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) is highly expressed in multiple cancers and inflammatory disorders where it stimulates secretion of matrix metalloproteinases (MMPs) and pro-inflammatory cytokines. EMMPRIN is amongst a subset of unique proteins that exist as a transmembrane protein but is released by cells in multiple uncharacterized forms. These extracellular forms have already been linked to at least half a dozen cancers and have been shown to contribute to a positive feedback loop during cancer progression. Thus, identifying the specific extracellular forms of EMMPRIN, characterizing how each of these forms contributes to disease progression, and identifying their cellular targets would significantly contribute to our understanding of cancer and inflammation. We have taken an integrative approach to fully characterize EMMPRIN and its role in disease progression by combining biological, biochemical, and atomic resolution studies. Our biological studies have already identified several extracellular forms of EMMPRIN in human blood and released by cancer cells that and the specific MMPs/cytokines secreted by these forms will be fully characterized here (Aim 1). To this end, we have developed recombinant expression systems that produce all the necessary proteins. We will then identify the cellular targets of these EMMPRIN forms by utilizing our recombinant proteins and characterize their interactions (Aim 2). Finally, we have begun solving the X-ray crystal structure and characterizing the solution behavior of a retinal-specific EMMPRIN isoform that contributes to retinoblastoma and here we will characterize this isoform both biophysically and biologically (Aim 3). Since EMMPRIN over-expression results in the deregulation of entire protein families integrally involved in the progression of multiple diseases, our combined biological and biophysical approach will fully characterize extracellular EMMPRIN at the biological and molecular levels, respectively. PUBLIC HEALTH RELEVANCE: Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) regulates many signaling pathways that become deregulated during dozens of cancers and inflammatory disorders, which include stimulating the secretion of MMPs and cytokines. Although EMMPRIN was initially identified as a cellular transmembrane protein, extracellular EMMPRIN has recently emerged as a central player in disease progression as well. However, little is known in regard to extracellular EMMPRIN and its interactions. We have discovered high levels of several extracellular EMMPRIN forms within human blood and we have already discovered that one of these is highly active. We have also established recombinant expression systems to produce all of these extracellular EMMPRIN forms that will allow us to characterize their activities here and we have initiated studies of a retinal-specific form of EMMPRIN that contributes to retinoblastoma. The proposed studies are focused on fully characterizing extracellular EMMPRIN forms in regard to their stimulatory activity of MMP/cytokine secretion and target interactions, providing insight into disease progression and the identification of novel therapeutic targets.