Adrenomedullin Signaling at the Maternal-Fetal Interface

描述（由申请人提供）：多功能肽血管扩张剂肾上腺髓质素（AM）通常通过称为降钙素受体样受体（Calcrl）的G蛋白偶联受体（GPCR）发出信号，此时受体与称为受体活性修饰蛋白（RAMP）的新型蛋白质结合。使用缺乏AM信号传导的每种组分的基因工程小鼠模型，我们发现AM信号传导的母体和胎儿来源对于协调正常胎儿生长所需的适当着床和胎盘形成都很重要。我们已经表明，母体AM参与了子宫对胚泡的接受性的内分泌准备，并且母体AM水平适度降低50%足以诱导与不良着床和胎盘形成相关的严重生殖缺陷。虽然完全缺乏AM及其典型受体导致胚胎死亡，由于淋巴管生成的缺陷，我们已经发现，胎儿AM也需要在妊娠中期的迷路层的正常分支血管生成。然而，我们还没有完全了解AM信号介导这些生殖作用在母胎界面的细胞机制。令人惊讶的是，并非AM遗传模型中的所有表型都在RAMP 2和RAMP 2模型中重现，这表明AM的功能可能通过受体非依赖性途径或通过尚未被充分认识的受体信号传导模式来赋予。在这方面，AM肽结合并增强补体因子H的活性，补体因子H是对正常着床重要的替代补体途径的负抑制剂。此外，AM肽还显示出激活趋化因子受体CXCR 7。因此，本提案中的研究旨在阐明AM作为母胎界面处先天免疫应答的调节剂通过规范、非规范或受体非依赖性机制的潜在作用。我们的目标将通过以下目标来实现：具体目标1是为了确定AM，补体因子H和CXCR 7在前接受，接受和不应期子宫阶段的空间和时间表达模式。使用一种新的遗传小鼠模型和遗传预先确定的囊胚移植实验，我们将确定是否胎儿和/或母体来源的AM可以影响这些信号分子的表达在母胎界面。在具体目标2中，我们将讨论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。在具体目标3中，我们将测试通过CXCR 7的AM信号传导是否代表植入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层衍生因子之间的分子联系。公共卫生相关性：我们已经发现，母体和胎儿来源的AM信号是重要的协调适当的植入和胎盘。我们假设AM通过非经典途径起作用，代表了调节母体先天免疫应答的重要胎儿源性信号。如果我们是正确的，那么我们将为控制母亲和胎儿之间微妙对话的过程提供新的见解，并在着床期间影响母体免疫反应的滋养层衍生因子之间提供分子联系。

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. PUBLIC HEALTH RELEVANCE: We have discovered that both maternal and fetal sources of AM signaling are important for orchestrating appropriate implantation and placentation. We hypothesize that AM, acting through non-canonical pathways, represents an important fetal-derived signal for modulating the maternal innate immune response. If we are correct, then we will 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.