Sex-specific mechanisms of cortical circuit dysfunction in a mouse ASD model

虽然ASD更多见于男性，但ASD的行为表现以及神经解剖学 与ASD相关的变化和脑功能障碍，在男性和女性之间有所不同。鲜为人知的 自闭症基因如何影响女性大脑。雌激素通过膜结合的雌激素受体α(ERα)起作用， 选择性地与雌性神经元中Gq偶联的第1组mGluRs、mGluR1和mGluR5相互作用并激活 调节信号、神经生理和行为的不同大脑区域。MGluRs的功能改变， 主要是mGluR5，与ASD小鼠模型的病理生理密切相关，尤其是脆性X 但许多其他药物和mGluR5拮抗剂正在对FXS儿童进行临床试验。我们是第一个 在FXS小鼠模型Fmr1 KO中发现mGluR5功能过度活跃，并展示了来自 异常的mGluR5复合体；mGluR5与其突触后支架蛋白Hmer分离，在 转而，导致结构性mGluR5活性，向下游效应器发出异常信号，并与疾病相关 表型，如电路过度兴奋。尽管有证据表明mGluR5与ASD的病理生理学有关，但 已知雌激素对mGluR1/5的性别依赖性调节，关于ASD相关基因如何与 雌激素影响mGluR1/5功能以及对ASD相关神经生理学和行为的后果。 我们发现了一种性别特异性的mGluR5依赖的感觉新皮质回路功能障碍 Pten(磷酸酶和张力蛋白同源基因缺失)缺失所致的ASD小鼠模型 10号染色体)，是PI3K/mTORC1途径的抑制子。具体地说，我们观察到过度兴奋 在两种不同的PTEN缺失模型的雌性中，新皮质回路振荡，称为向上状态；胚胎， Pten基因在海马区和第5层新皮质神经元中的敲除，以及一个生殖系Pten杂合子小鼠 (PTEN-HET)，这是一种人类Pten相关ASD的遗传有效模型。超激发上能态 急性拮抗mGluR5或ERα可纠正雌性PTEN模型，提示mGluR5- ERα信令。MGluR5-ERα活性增强的候选分子底物是观察到的 雌性大鼠大脑皮质mGluR5-ERα和mGluR5-Hmer复合体减少。我们假设一个 Pten缺失的雌性神经元中mGluR5与ERA和Hmer相互作用的不平衡导致 增强mGluR5信号对雌激素的反应，作用于ERα，以及结构性活性 MGluR5，导致过度兴奋的大脑皮层振荡和ASD相关行为。我们建议 以下旨在验证这一假说：目标1：确定性别相关的PTEN和ERα的相互作用 皮质环路功能障碍和mGluR5复合体调节。目的2：研究mGluR5的性别特异性效应 和ERα对Pten缺失的第5层神经元的固有和突触特性的影响。目标3：确定特定的性别， Pten缺失模型中依赖mGluR5和ERα的活体皮质振荡与脑电的关系。目标4.确定 女性特有的、依赖Pten的皮质回路超兴奋性在ASD相关行为中的作用。

Although ASD is more diagnosed in males, the behavioral manifestations of ASD, as well as the neuroanatomical changes and brain dysfunction associated with ASD, differ between males and females. There is little known of how ASD genes impact the female brain. Estrogen, acting through membrane bound estrogen receptor α (ERα), interacts with and activates Gq-coupled Group 1 mGluRs, mGluR1 and mGluR5, selectively in female neurons in diverse brain regions to regulate signaling, neurophysiology, and behavior. Altered functioning of mGluRs, primarily mGluR5, is strongly implicated in the pathophysiology of ASD mouse models, most notably Fragile X Syndrome, but many others, and mGluR5 antagonists are in clinical trials of FXS children. We were the first to discover hyperactivity of mGluR5 function in the FXS mouse model, Fmr1 KO, and show this results from an abnormal mGluR5 complex; mGluR5 is dissociated from its postsynaptic scaffolding protein, Homer, which, in turn, leads to constitutive mGluR5 activity, abnormal signaling to downstream effectors and disease relevant phenotypes, such as circuit hyperexcitability. Despite the evidence for mGluR5 in ASD pathophysiology, the known sex-dependent regulation of mGluR1/5 by estrogen, little is known of how ASD-linked genes interact with estrogen to affect mGluR1/5 function and the consequences on ASD-relevant neurophysiology and behavior. We have discovered a sex-specific, mGluR5 -dependent dysfunction of sensory neocortical circuits in a mouse model of ASD that results from deletion of Pten (Phosphatase and tensin homolog deleted on chromosome 10), a suppressor of the PI3K/mTORC1 pathway. Specifically, we observe hyperexcitable neocortical circuit oscillations, termed UP states, in females of two distinct PTEN deletion models; an embryonic, knockout of Pten in hippocampus and layer 5 neocortical neurons, and a germline Pten heterozygous mouse (Pten-het), which is a genetically valid model for Pten-related ASD in humans. Hyperexcitable UP states in female Pten models are corrected by acute antagonism of mGluR5 or ERα, indicative of hyperactive mGluR5- ERα signaling. A candidate molecular substrate for enhanced mGluR5-ERα activity is the observed increase in mGluR5-ERα, and decreased mGluR5-Homer, complexes in female Pten-het cortex. We hypothesize that an imbalance in mGluR5 interactions with ERa and Homer in Pten deleted female neurons results in enhanced mGluR5-signaling in response to estrogen, acting on ERα, as well as constitutively active mGluR5 which leads to hyperexcitable cortical oscillations and ASD-relevant behaviors. We propose the following aims to test this hypothesis: Aim 1: Determine the sex-dependent interactions of Pten and ERα in cortical circuit dysfunction and mGluR5 complex regulation. Aim 2: Examine the sex-specific effects of mGluR5 and ERα on intrinsic and synaptic properties of Pten-deleted layer 5 neurons. Aim 3: Determine the sex-specific, mGluR5- and ERα-dependent in vivo cortical oscillations with EEG in Pten deletion models. Aim 4. Determine the role of female-specific, Pten-dependent cortical circuit hyperexcitability in ASD-relevant behaviors.