Adrenomedullin Signaling at the Maternal-Fetal Interface

描述(申请人提供)：多功能多肽血管扩张剂肾上腺髓质素(AM)通常通过一种名为降钙素受体样受体(Calcrl)的G蛋白偶联受体(GPCR)与一类名为受体活性修改蛋白(RAMP)的新型蛋白质结合而发出信号。使用缺乏AM信号每个组件的基因工程小鼠模型，我们发现母体和胎儿的AM信号来源对于协调正常胎儿生长所需的适当植入和胎盘形成都是重要的。我们已经证明，母体AM参与了子宫的内分泌准备，以便接受胚泡，并且母体AM水平适度降低50%就足以导致与不良着床和胎盘形成相关的严重生殖缺陷。虽然AM及其典型受体的完全缺失会由于淋巴管生成缺陷而导致胚胎死亡，但我们发现胎儿AM也是妊娠中期迷路层正常分支血管生成所必需的。然而，我们还没有完全了解AM信号在母胎界面介导这些生殖效应的细胞机制。令人惊讶的是，并不是AM遗传模型中的所有表型都在CLR和RAMP2模型中概括，这表明AM的功能可能是通过受体独立的途径或通过迄今尚未被充分认识的受体信号范例来传递的。在这一点上，AM多肽结合并增强补体因子H的活性，补体因子H是替代补体途径的负抑制物，对正常植入非常重要。此外，AM肽还被证明能激活趋化因子受体CXCR7。因此，本研究的目的是阐明AM作为母胎界面天然免疫反应的潜在调节因子，通过规范、非规范或受体非依赖的机制。我们的目标将通过以下目标来实现：具体目标1旨在确定AM、补体因子H和CXCR7在子宫接受前、接受和难治期的时空表达模式。利用一种新的小鼠遗传模型和预先确定的胚泡移植实验，我们将确定胎儿和/或母体来源的AM是否会影响这些信号分子在母胎界面的表达。在特定的目标2中，我们将解决AM信号的遗传剂量的变化是否会影响母胎界面的替代补体途径。在特定的目标3中，我们将测试AM通过CXCR7的信号是否代表着床期间母体螺旋动脉适当重塑的主要机制。通过完成这些目标，我们希望为控制母亲和胎儿之间微妙对话的过程提供新的见解，并提供影响着床期间母体免疫反应的滋养细胞衍生因子之间的分子联系。

DESCRIPTION (provided by applicant): The multifunctional peptide vasodilator adrenomedullin (AM) typically signals through a G-protein coupled receptor (GPCR) called calcitonin receptor-like receptor (Calcrl) when the receptor is bound to a novel class of proteins called receptor activity modifying proteins (RAMPs). Using genetically engineered mouse models lacking each of the components of AM signaling, we have found that both maternal and fetal sources of AM signaling are important for orchestrating appropriate implantation and placentation that are required for normal fetal growth. We have shown that maternal AM is involved in the endocrine preparation of the uterus for receptivity to the blastocyst and that a modest 50% reduction in maternal AM levels is sufficient to induce profound reproductive defects associated with poor implantation and placentation. While complete absence of AM and its canonical receptors leads to embryonic lethality due to defects in lymphangiogenesis, we have discovered that fetal AM is also required for the normal branching angiogenesis of the labyrinth layer at mid-gestation. However, we have yet to fully understand the cellular mechanisms through which AM signaling mediates these reproductive effects at the maternal-fetal interface. Surprisingly, not all of the phenotypes in the AM genetic model are recapitulated in the CLR and RAMP2 models, which suggests that the functions of AM may be imparted through receptor-independent pathways or through as yet under-appreciated receptor signaling paradigms. In this regard, AM peptide binds to and potentiates the activity of Complement Factor H, a negative inhibitor of the alternative complement pathway that is important for normal implantation. In addition, AM peptide has also been shown to activate a chemokine receptor, CXCR7. Therefore, studies in this proposal are aimed at elucidating the potential roles of AM as a regulator of the innate immune response at the maternal-fetal interface through canonical, non-canonical or receptor- independent mechanisms. Our goals will be met through the following aims: Specific Aim 1 is geared toward determining the spatial and temporal expression pattern of AM, Complement Factor H and CXCR7 during the pre-receptive, receptive and refractory uterine phases. Using a novel genetic mouse model and genetically pre-determined blastocyst transfer experiments, we will determine whether fetal and/or maternal sources of AM can influence the expression of these signaling molecules at the maternal-fetal interface. In Specific Aim 2 we will address whether changes in the genetic dosage of AM signaling can affect the alternative complement pathway at the maternal-fetal interface. In Specific Aim 3 we will test whether AM signaling through CXCR7 represents a major mechanism for the appropriate remodeling of maternal spiral arteries during implantation. By completing these aims we hope to provide novel insights into the processes that govern the delicate dialogue between mother and fetus and provide a molecular link between trophoblast-derived factors that influence the maternal immune response during implantation.