Decoy Receptors in Lymphangiogenesis

描述(申请人提供)：淋巴管系统与多种病理生理过程有关，包括肿瘤转移、组织炎症、水肿、免疫监视受损和脂肪吸收障碍。然而，值得注意的是，现代医学还没有发现调节淋巴管生长或功能的药物靶点；这主要是因为控制淋巴管生成的分子机制仍然知之甚少。我们的实验室已经证明，肾上腺髓质素(AM)是一种由淋巴管内皮细胞(LECs)分泌的52个氨基酸的多肽，对于胚胎淋巴管的正常发育是必不可少的，微调控制AM的剂量对于调节胚胎和病理淋巴管的生成都是至关重要的。CXCR7最初被鉴定为AM受体，但最近因其作为SDF-1的诱骗受体而被研究。我们的初步研究表明，CXCR7在发育中的晶状体上皮细胞中表达，CXCR7-/-小鼠表现出与AM过度表达一致的淋巴表型。因此，我建议研究一种假设，即CXCR7作为AM的诱骗受体，从而微调控制AM介导的晶状体上皮细胞的增殖。我将对功能丧失的CXCR7-/-小鼠的淋巴管生成进行全面的表型分析，以确定CXCR7在体内淋巴管生成中的作用。此外，我建议将CXCR7-/-小鼠与AM单倍体不足的小鼠杂交，以测试CXCR7的诱骗活性是否对AM介导的体内淋巴管生成的控制是必需的。我还将使用功能丧失和功能获得的体外模型来阐明CXCR7是否抑制AM介导的下游信号转导。培养的晶状体上皮细胞将与AM一起进行增殖试验、免疫印迹试验和3D球体萌发试验，以探讨CXCR7在AM介导的LEC增殖、下游信号转导和成熟血管形成中的作用。这项研究的结果将确定CXCR7在AM信号和淋巴管生成中的作用，并可能阐明治疗管理不善的淋巴管疾病的新的治疗靶点。

DESCRIPTION (provided by applicant): The lymphatic vasculature has been implicated in a variety of pathophysiological processes, including tumor metastasis, tissue inflammation, edema, impaired immune surveillance and disrupted fat absorption. Nevertheless, it is remarkable that modern medicine has yet to discover pharmacologically-tractable targets for the modulation of lymphatic vessel growth or function; largely because the molecular mechanisms that control lymphangiogenesis remain poorly understood. Our lab has shown that adrenomedullin (AM), a 52-amino acid peptide that is secreted by lymphatic endothelial cells (LECs), is essential for proper embryonic lymphatic vascular development and that fine-tuned control of AM dosage is critical for the regulation of both embryonic and pathological lymphangiogenesis. CXCR7 was originally identified as an AM receptor, but has more recently been studied for its functions as a decoy receptor for SDF-1. Our preliminary studies suggest that CXCR7 is expressed in developing LECs and that CXCR7-/- mice exhibit lymphatic phenotypes consistent with AM overexpression. Therefore, I propose to investigate the hypothesis that CXCR7 serves as a decoy receptor for AM which consequently provides fine-tuned control of AM-mediated proliferation of LECs. I will perform comprehensive phenotypic analysis of lymphangiogenesis in loss-of-function CXCR7-/- mice in order to define the role of CXCR7 during in vivo lymphangiogenesis. In addition, I propose to cross CXCR7-/- mice to mice that are haploinsufficient for AM in order test whether the decoy activity of CXCR7 is required for the control of AM- mediated lymphangiogenesis in vivo. I will also use both loss-of-function and gain-of-function in vitro models to elucidate whether CXCR7 dampens AM-mediated downstream signaling. LECs will be cultured and treated with AM for proliferation assays, immunoblot, and 3D spheroid sprouting assays to explore the role of CXCR7 on AM-mediated LEC proliferation, downstream signaling, and mature vessel formation. Results from this proposal will define the role of CXCR7 in AM signaling and lymphangiogenesis and may elucidate novel therapeutic targets for the treatment of poorly managed lymphatic vascular diseases.