Neural Control of the Prepubertal Ovary

描述（由申请人提供）：关于控制卵巢发育的激素机制已知之甚多。最近，该领域的一个主要关注点是确定在卵巢微环境中运作的有助于获得卵巢生殖能力的调控途径。在这个框架内，我们的实验室已经开发出的概念，神经营养因子（NT）和他们的Trk酪氨酸激酶受体，长期以来被认为是专门需要的神经系统的发展也参与卵巢功能的控制。采用基因靶向方法，我们确定了trkB，神经营养因子-4/5（NT-4/5）和脑源性神经营养因子（BDNF）的高亲和力受体，作为早期卵泡生长和卵母细胞存活所需的信号分子。此外，我们发现，神经生长因子（NGF）有助于独立的卵泡生长的启动。其他研究表明，通过trkA受体的神经生长因子的作用也是重要的排卵，但尽管这种生理作用，在卵巢内的神经生长因子合成的不适当的持续增加的结果在功能上的改变，导致卵泡囊肿的发展。基于这些发现，本更新申请提出了以下具体目的：1）定义早期卵泡生长和卵母细胞存活所需的TrkB受体同种型（全长或截短的），并鉴定主要响应TrkB信号传导的细胞。该目标的目的将使用Cre-loxP技术实现，以特异性破坏卵母细胞或颗粒细胞中全长和截短TrkB亚型的表达。2)验证NTs通过TrkB受体信号传导通过支持卵母细胞-颗粒细胞Jagged 1-Notch 2通讯途径促进早期卵泡生长的假设。这一目标将通过细胞特异性trkB科斯和细胞/生物化学方法的组合使用来实现，以定义TrkB信号传导和Notch 2途径之间存在的关系。3)为了验证以下假设，即虽然有腔卵泡的正常发育和排卵需要NGF依赖的trkA信号传导，但过量的NGF会损害有腔卵泡达到排卵前阶段的能力，从而建立导致多囊卵巢发育的条件。为了实现这一目标，我们将使用以细胞特异性方式过表达NGF的转基因小鼠，以及在卵巢细胞中通过p75（常见NT受体）或trkA（高亲和力NGF受体）的信号传导被条件性破坏的小鼠。4)为了验证这一假设，即过量的卵巢NGF在局部微环境中创造了有利于非人类灵长类动物多囊卵巢发育的条件。为了实现这一目标，我们将使用慢病毒递送系统来增强成年非人灵长类动物卵巢间质区室中NGF的产生。

DESCRIPTION (provided by applicant): Much is known about the hormonal mechanisms controlling ovarian development. More recently, a major focus of attention in the field has been the identification of regulatory pathways that, operating within the ovarian microenvironment, contribute to the acquisition of ovarian reproductive competence. Within this framework, our laboratory has developed the concept that neurotrophins (NTs) and their Trk tyrosine kinase receptors, long thought to be exclusively required for the development of the nervous system are also involved in the control of ovarian function. Employing gene targeting approaches we identified trkB, the high-affinity receptor for neurotrophin-4/5 (NT-4/5) and brain-derived neurotrophic factor (BDNF), as a signaling molecule required for early follicular growth and oocyte survival. In addition, we showed that nerve growth factor (NGF) contributes independently to the initiation of follicular growth. Other studies indicated that NGF acting via trkA receptors is also important for ovulation, but that despite this physiological role, an inappropriately sustained increase in intraovarian NGF synthesis results in functional alterations leading to the development of follicular cysts. Based on these findings, the present renewal application proposes the following Specific Aims: 1) To define the TrkB receptor isoform (full-length or truncated) required for early follicle growth and oocyte survival, and identify the cells primarily responsive to TrkB signaling. The objectives of this Aim will be achieved using Cre-loxP technology to specifically disrupt the expression of full-length and truncated TrkB isoforms in either oocytes or granulosa cells. 2) To test the hypothesis that NTs signaling via TrkB receptors promote early follicular growth by supporting an oocyte-to granulosa cell Jagged 1-Notch2 communication pathway. This aim will be achieved with the combined use of cell-specific trkB KOs and cellular/biochemical approaches to define the relationship that exists between TrkB signaling and the Notch2 pathway. 3) To test the hypotheses that while NGF-dependent trkA signaling is required for the normal development of antral follicles and ovulation, an overproduction of NGF compromises the ability of antral follicles to reach a preovulatory stage, and thus establishes conditions leading to the development of polycystic ovaries. To accomplish this Aim we will use transgenic mice that overexpress NGF in a cell specific manner, and mice in which signaling through p75 (the common NT receptor), or trkA (the high-affinity NGF receptor) are conditionally disrupted in ovarian cells. 4) To test the hypothesis that an excess of ovarian NGF creates conditions in the local microenvironment that favor the development of polycystic ovaries in nonhuman primates. To accomplish this Aim we will use a lentiviral delivery system to enhance the production of NGF in the interstitial compartment of the adult nonhuman primate ovary.