Dissecting Estrogen Control of Sexual Differentiation of the Brain

描述（由申请人提供）：在这个提案中，我将研究利用类固醇激素使终纹床核雄性化的细胞和分子机制，终纹床核是神经回路中的一个重要节点，产生两性二态行为，如交配和攻击。BNST与下丘脑和杏仁核相互连接，其结构是两性二态的，雄性的神经元更多。经典的内分泌研究和基因功能丧失实验都表明，类固醇激素及其受体也是男性典型行为所必需的。雄激素受体（AR）在雄性BNST中表达较多。我的研究结果表明，雌性激素在生命的最初几天以雄性特异性的方式指导BNST的性别分化，部分是通过雄性特异性的AR调节。我建议研究两个与雌性激素在BNST中产生两性异形的作用有关的问题。1)雌激素在脑AR表达中产生性别二态性的机制是什么？2)雌激素介导的BNST雄性化的遗传程序是什么？通过回答这些问题，我希望能够确定大脑中产生性别特异性细胞群的机制。Aim 1的目的是证明雌激素在激活男性特异性AR表达模式中的直接作用。我将利用先前发表的AR- ipin报告小鼠，在所有AR阳性细胞中表达LacZ，来评估AR表达对雌激素的需求。通过染色质免疫沉淀分析（ChIP），我将证明雌性激素受体α (ERa)直接募集到雄性新生儿BNST的AR位点。这些研究将揭示BNST中AR表达性别二态性产生的机制。我假设，除了调节AR表达外，雌激素信号还控制BNST中许多基因的性别特异性表达。Aim 2的目标是通过微阵列分析确定发育中的BNST中由ERcx调节的其他两性二态基因。这些基因将为激素在调节大脑性别分化中的作用提供重要的见解。我的实验将阐明控制脑内一个重要区域——中脑皮层性别分化的基本机制。许多精神疾病，如自闭症和抑郁症，都存在性别偏倚的比例。了解大脑是如何经历性别分化的，可能会促进我们对导致许多这些疾病的基本机制的理解。

DESCRIPTION (provided by applicant): In this proposal, I will investigate the cellular and molecular mechanisms utilized by steroid hormones to masculinize the bed nucleus of the stria terminalis (BNST), an important node in the neural circuits that generate sexually dimorphic behaviors such as mating and aggression. The BNST is reciprocally connected with the hypothalamus and amygdala, and its structure is sexually dimorphic, with more neurons in males. Both classic endocrine studies, and genetic loss-of-function experiments indicate that steroid hormones and their receptors are also required for male-typical behaviors. Androgen receptor (AR) is expressed in more cells in the male BNST. My findings indicate that estrogen acts in a male-specfic manner during the first few days of life to direct sexual differentiation of the BNST, in part through male-specific regulation of AR. I propose to investigate two questions relating to the role of estrogen in generating sexual dimorphism in the BNST. 1) What are the mechanisms by which estrogen generates sexual dimorphism in AR expression in the brain? 2) What is the genetic program mediated by estrogen to masculinize the BNST? By answering these questions, I hope to define the mechanisms which generate a sex-specific cell population in the brain. The goal of Aim 1 is to demonstrate a direct role for estrogen in activating a male-specific expression pattern of AR in the BNST. I will utilize the previously published AR-IPIN reporter mice, which express LacZ in all AR-positive cells, to evaluate the requirement for estrogen in AR expression. Through chromatin immunoprecipitation analysis (ChIP), I will demonstrate the direct recruitment of estrogen receptor alpha (ERa) to the AR locus in the neonatal BNST of males. These studies will reveal the mechanisms for generating sexual dimorphism in AR expression in the BNST I hypothesize that, in addition to regulating AR expression, estrogen signaling controls the sex-specific expression of many genes in the BNST. The goal of Aim 2 is to identify additional sexually dimorphic genes regulated by ERcx in the developing BNST through microarray analysis. These genes will provide important insight into the role of hormones in regulating sexual differentiation of the brain. My experiments will elucidate the fundamental mechanisms that control sexual differentiation of an important brain region, the BNST. Many psychiatric conditions such as autism and depression present with sex-biased ratios. Understanding how the brain undergoes sexual differentiation is likely to advance our understanding of the basic mechanisms that lead to many of these disorders.