NPY and Angiogenesis in Adipose Tissue

描述(申请人提供)：白色脂肪组织(WAT)是高度血管化的，其生长可以被抗血管生成药物抑制，有望成为治疗肥胖症的新方法。在之前的资助期间，我们发现神经肽Y(NPY)是一种交感神经递质，通过其GI偶联的Y2受体、二肽基肽酶IV(DPPIV，形成Y2激动剂的酶)和内皮型一氧化氮合酶(ENOS)而有效地促进血管生成，并在缺血、动脉粥样硬化、肿瘤和视网膜病变中刺激血管生成。由于WAT有交感神经，压力会激活它们--我们假设NPY是WAT血管生成和脂肪生成的神经源性介质。在试点研究中，NPY增加，而Y2拮抗剂在ob/ob小鼠的腹部局部应用时减少脂肪沉积(MRI)和血管密度；同样，在Y2-/-小鼠中，冷应激和高脂饮食诱导的腹型肥胖得到减少。为了确定NPY是否激活血管生成成脂营养循环，以及通过何种机制，将在人和小鼠、野生型和Y2、DPPIV、eNOS(NPY的血管生成信号)及其来源的细胞中研究血管生成和脂肪生成。为了在WAT中模拟神经-血管-脂肪细胞的相互作用，我们将使用已建立的交感神经母细胞瘤或大鼠颈上神经节与人和小鼠Wat的内皮细胞或前脂肪细胞的共培养。在AIMS 1-2中将确定NPY神经元表达的上游调节器及其血管生成和脂肪生成/抗脂分解的下游调节器。目的3将测试人或小鼠脂肪垫在异种移植裸鼠模型中的生长是否受到NPY或宿主交感神经支配(交感神经切除)的刺激，并依赖于血管生成(MRI、超声、组织学)。在目标4中，NPY和Y2Rs的作用将被证实在遗传或应激高脂饮食诱导的肥胖中，使用Y2拮抗剂进行局部治疗，并产生内皮和脂肪细胞特异性的Y2条件敲除。如果得到证实，NPY及其Y2Rs可能成为压力依赖型肥胖的一个新的风险因素，因为它的血管生成活性。

DESCRIPTION (provided by applicant): White adipose tissue (WAT) is highly vascularized and its growth can be inhibited by anti-angiogenic drugs, promising new treatment for obesity. In the previous grant period, we discovered that neuropeptide Y (NPY), a sympathetic transmitter, is potently angiogenic via its Gi-coupled Y2 receptors, dipeptidyl peptidase IV (DPPIV, an enzyme forming Y2 agonist) and an endothelial nitric oxide synthase (eNOS) - and stimulates angiogenesis in ischemia, atherosclerosis, tumors and retinopathy. Since WAT has sympathetic nerves and stress activates them - we hypothesized that NPY is a neurogenic mediator of WAT angiogenesis and adipogenesis. In pilot studies, NPY increased, while Y2 antagonist decreased fat deposits (MRI) and vascular density when applied locally into abdominal WAT of ob/ob mice; similarly, cold stress- and high fat diet-induced abdominal obesity was reduced in Y2-/- mice. To determine if NPY activates angiogenic adipogenic trophic cycle, and by which mechanisms, angiogenesis and adipogenesis will be studied in human WAT and mice, wild type and null for Y2, DPPIV, eNOS (NPY's angiogenic signals), and cells derived from them. To mimic nerve-vessel-adipocyte cross-talk in WAT, we will use established co-culture of NPYergic sympathetic neuroblastoma or rat superior cervical ganglia with endothelial cells or preadipocytes from human and murine WAT. Upstream modulators of NPY neuronal expression and its downstream modulators of angiogenesis and adipogenesis/anti-lipolysis will be determined in Aims 1-2. Aim 3 will test if growth of human or murine fat pad in a xenograft nude mouse model is stimulated by NPY or host sympathetic innervation (sympathectomy) and dependent on angiogenesis (MRI, ultrasound, histology). In Aim 4, the role of NPY and Y2Rs will be confirmed in genetic or stress+high fat diet-induced obesity, using local treatment with Y2 antagonist and generating endothelial and adipocyte-specific conditional Y2 knockouts. If proven, NPY and its Y2Rs may become a new risk factor for stress-dependent obesity, due to its angiogenic activity.