Decoy Receptors in Lymphangiogenesis

描述（由申请人提供）：淋巴管系统涉及多种病理生理过程，包括肿瘤转移、组织炎症、水肿、免疫监视受损和脂肪吸收中断。然而，值得注意的是，现代医学尚未发现调节淋巴管生长或功能的药理学上可处理的靶标；很大程度上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）是一种由淋巴内皮细胞（LECs）分泌的52个氨基酸的肽，对胚胎淋巴血管的正常发育至关重要，微调AM的剂量对胚胎和病理性淋巴管生成的调节至关重要。CXCR7最初被确定为AM受体，但最近研究其作为SDF-1的诱饵受体的功能。我们的初步研究表明，CXCR7在发育中的LECs中表达，并且CXCR7-/-小鼠表现出与AM过表达一致的淋巴表型。因此，我建议研究CXCR7作为AM的诱饵受体的假设，从而提供AM介导的LECs增殖的微调控制。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单倍不足的小鼠杂交，以测试CXCR7的诱饵活性是否需要在体内控制AM介导的淋巴管生成。我还将使用体外功能丧失和功能获得模型来阐明CXCR7是否抑制am介导的下游信号传导。将用AM培养和处理LEC，进行增殖试验、免疫印迹和3D球体发芽试验，以探索CXCR7在AM介导的LEC增殖、下游信号传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信号传导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.