Understanding the role of endothelial Zeb1 in lymphatic vessels

新血管的形成在癌症和心血管系统疾病中很重要。利用从人类血管中分离出来的细胞进行培养，我们最近发现了一种蛋白质，它可以改变这些细胞的新陈代谢，使它们成熟并停止生长。这种蛋白质已经被证明与发育和癌细胞有关，但之前没有被证明与血管细胞有关。我们在培养细胞中进行的实验预测，这种蛋白质将控制心血管疾病时血管的生长方式，我们正在研究这在小鼠模型中的重要性。然而，我们最近发现，在淋巴管（将组织中的液体和细胞送回血液的血管）中，同样的蛋白质也以同样的方式受到调节。过多的组织液会导致疼痛和衰弱，如淋巴水肿，而淋巴管是肿瘤细胞转移的主要途径，也与肥胖期间的脂肪沉积有关。因此，了解淋巴管如何正常运作，以及如何控制这种功能是至关重要的。淋巴管（LV）是血管系统的重要组成部分，控制间质液平衡、炎症过程、脂质、蛋白质和免疫细胞在全身的运输。虽然在过去100年左右的大部分时间里，淋巴系统的衰竭一直与淋巴水肿有关，但最近的研究表明，淋巴的生长和功能是多种不同疾病的基础，包括1)增强免疫治疗的疗效，2)减少与缺血心脏组织血运重建不良相关的炎症，3)神经变性，4)转移性扩散，5)肾功能衰竭和6)代谢性疾病等。对于任何血管，包括血液，为了对其环境做出反应，内皮细胞（ECs）将其表型从静止变为激活。这是最近通过使用单细胞RNASeq得出的结论，它提供了关于存在的不同EC表型的信息，但关于它们如何产生的信息有限。因此，不同EC行为的转录控制对于理解不同表型是如何产生的至关重要。我们已经确定了一种转录因子（称为Zeb1），它在淋巴管生长过程中受到动态调节，其正常特征诱导“静止”而不是“激活”表型。这项工作将扩展我们的体内和分子特征，以确定Zeb1信号在淋巴生长的正常发育和病理模型中的影响。因此，转录因子活性可能是产生不同LEC表型的信号通路之一。我们推测Zeb1是淋巴系统中第一个被发现的控制生长过程中LEC表型异质性的转录因子。上述数据表明，Zeb1的缺失将通过减少淋巴EC的静止来激活淋巴内皮。我们将通过实现以下目标来验证这一假设：目标1：内皮特异性ZEB1 koin的淋巴管特征；目标2:ZEB1 ieckoin的病理性淋巴重塑特征；目标3：确定导致ZEB1下调的信号事件

The formation of new blood vessels is important in cancer and diseases of the cardiovascular system. Using cells isolated from human blood vessels and grown in culture, we recently discovered a protein that can switch the metabolism of these cells so that they can mature and stop growing. This protein has been shown to be involved in development and in cancer cells, but not previously in blood vessel cells. Our experiments in cultured cells predict that this protein would control how blood vessels grow in response to cardiovascular disease, and we are working on how this is important in mice models. However, we recently discovered that the same protein is regulated in the same way in lymphatic vessels (vessels that return fluid and cells from the tissue back into the bloodstream). Excess tissue fluid causes painful and debilitating conditions such as lymphedema, and lymphatic vessels are the primary route of tumour cell metastasis and also involved in fat deposition during obesity. Therefore, understanding how lymphatic vessels normally function, and how that function is controlled is of essential importance. Lymphatic vessels (LV) are an essential component of the vascular system that control interstitial fluid balance, inflammatory processes, lipid, protein and immune cell transport throughout the body. While for most of the last hundred years or so failure of the lymphatic system has been associated with lymphoedema, more recently it has demonstrated that lymphatic growth and function is a underpins multiple diverse disease involved processes including 1) enhancing efficacy of immunotherapy, 2) reducing inflammation associated with poor revascularisation of ischaemic cardiac tissue 3) neurodegeneration 4) metastatic spread 5) renal failure and 6) metabolic diseases to name a few. For any vessel, including blood, to respond to its environment the endothelial cells (ECs) change their phenotype from a quiescent, to an activated. This has been born out most recently through the use of single cell RNASeq, which provides information regarding the different EC phenotypes that exist, but limited information regarding how they are made. Transcriptional control of different EC behaviour is therefore of key importance to understand how the different phenotypes arise. We have identified a transcription factor (called Zeb1) that is dynamically regulated during lymphatic vessel growth, and its normal signature induces a 'quiescent' rather than 'activated' phenotype. This work will expand on our in vivo and molecular characterisation to determine the impact of Zeb1 signalling in normal development and pathological models of lymphatic growth. Therefore, transcription factor activity is likely to be one of the signalling pathways in which different LEC phenotypes could arise. We speculate that Zeb1 is, the first identified transcription factor for the lymphatic system that controls LEC phenotypic heterogeneity during growth All the above data suggests that loss of Zeb1 will prime the lymphatic endothelium by reducing lymphatic EC quiescence. We will test this hypothesis by achieving the following aims:Aim 1: Characterisation of lymphatic vessels in an endothelial specific ZEB1 KOAim 2: Characterisation of pathological lymphatic remodelling in Zeb1 iECKOAim 3: Determination of signalling events leading to Zeb1 downregulation