Mechanisms and Rescue of Neural Circuit Dysfunction in Mecp2 Mutant Mice

Mecp2突变小鼠神经回路功能障碍的机制及拯救

• 批准号: 8804065
• 负责人: Hui Lu
• 金额: $ 9.26万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-30 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8804065
• 关键词: Accounting; Action Potentials; Acute; Address; Affect; Age; Alleles; Animals; Anxiety; Applications Grants; Autistic Disorder; Behavior; Behavioral; Brain region; Budgets; Calcium; Childhood; Chronic; Complex; Data; Defect; Development; Disease; Disease Progression; Electronic Mail; Enrollment; Epilepsy; Explosion; Face; Female; Functional disorder; Genes; Genetic; Head; Hippocampus (Brain); Homeostasis; Human; Human Resources; Image; Impaired cognition; Individual; Intellectual functioning disability; Intervention; Joints; Journals; Knock-out; Lead; Learning; Link; Measures; Memory; Mentors; Microcephaly; Microscope; Molecular; Motor; Motor Skills; Mus; Mutant Strains Mice; Mutation; Nature; Neurons; Pathogenesis; Pattern; Phase; Phenotype; Pyramidal Cells; Research; Rett Syndrome; Schedule; Scientist; Slice; Speech; Suggestion; Supervision; Syndrome; Technology; Telephone; Time; Training; Work; autism spectrum disorder; awake; base; career; design; excitatory neuron; gamma-Aminobutyric Acid; genetic technology; girls; hippocampal pyramidal neuron; in vivo; inhibitory neuron; insight; learned behavior; loss of function mutation; male; meetings; mouse model; mutant; nervous system disorder; neural circuit; neurogenetics; neuronal excitability; neuronal patterning; neuropsychiatry; novel therapeutic intervention; overexpression; public health relevance; response; skills; social; symposium; tool

 DESCRIPTION (provided by applicant): Neurogenetic studies provided insight into molecular basis of tens of childhood neurological diseases but in the context of intellectual disabilities an autism spectrum disorders (ASDs) the challenge is how one can explain, similar phenotypes in face of vastly different molecular perturbations. This led to the proposal that the observed behaviors result from some shared patterns of circuit dysfunction. There is a pair of disorders with overlapping phenotypes that presents a unique opportunity to explore circuit-level disruption of homeostasis and its sequelae, particularly for learning and memory: Rett syndrome (RTT), caused by loss-of-function mutations in the X-linked MECP2, and MECP2 duplication syndrome, caused by duplications (or triplications) of the gene. The mechanism accounting for overlapping phenotypes in two syndromes with opposite molecular defects (and transcriptional alterations) remains mysterious. My preliminary data show that both loss and gain of MeCP2 function leads to increased cross-correlations of spontaneous calcium activity and increased sensitivity to GABA blockade in acutely isolated hippocampal slices. This hypersynchrony is caused by an imbalance of excitation and inhibition in the hippocampal circuit. The objective of this proposal is to characterize the malfunction of the hippocampal CA1 circuit in mouse models of RTT and MECP2 duplication syndrome and to explore the possibility of intervention and rescue. I hypothesize that loss and gain of MeCP2 function generates similar patterns of malfunction (circuitopathies) in "canonical" neural circuits, and that these circuitopathies can be rescued by restoring the imbalance of excitation and inhibition. To address this hypothesis, I propose three specific aims: (1) Elucidate the cellular mechanism underlying the malfunction of hippocampal CA1 circuit caused by MeCP2 dysfunction; (2) Determine how the circuit in hippocampal CA1 responds during learning tasks in Mecp2 mutants; (3) Determine whether altering cellular excitability acutely or chronically can rescue circuit malfunction in MeCP2 disorders. Given that circuit function is what eventually determines behavior, these studies will elucidate the circuit-level mechanism accounting for overlapping phenotypes of Rett syndrome and MECP2 duplication syndrome. It will also reveal the circuit's response to a hippocampal dependent learning behavior and uncover potential correlations between circuit malfunction and behavioral deficits. The data will provide insights into the value of manipulations at the circuit level and might lead to the design of new therapeutic approaches. Research proposed in the K99 mentored phase (year 1 and 2) is concentrated on generating multiple genetic mouse lines to elucidate the cellular mechanism of circuit malfunctions caused by Mecp2 mutation and establishing in vivo calcium imaging with a miniature head-mounted microscope on freely moving mice performing a learning task, all of which will be carried out with the supervision of Dr. Huda Y. Zoghbi and Dr. Stelios Smirnakis. During this phase, I will acquire training on new skills to directly prepare me for a career as an independent research scientist through scheduled weekly lab meetings, mentor supervision and discussion sessions, attending weekly departmental seminars, journal clubs and retreats, participation in joint lab and co- institutional meetings, attendance and participation at national scientific conferences, and enrollment in formal courses. The R00 Independent phase (year 3 to 5) will focus on determining how the circuit in hippocampal CA1 responds during learning tasks in Mecp2 mutants and explore the rescue of Mecp2 disorders. During this phase, I will continue an active relationship with my mentors through scheduled phone conversations and email. I will rely on their input and advice towards hiring lab personnel, budget development, and developing a successful R01 grant application.

 描述（由申请人提供）：神经遗传学研究深入了解了数十种儿童神经系统疾病的分子基础，但在智力障碍和自闭症谱系障碍（ASD）的背景下，面临的挑战是如何解释面对截然不同的分子扰动的相似表型。这导致了这样的提议：观察到的行为是由电路功能障碍的一些共享模式引起的。有两种具有重叠表型的疾病为探索体内平衡的环路水平破坏及其后遗症提​​供了独特的机会，特别是对于学习和记忆：雷特综合征（RTT），由 X 连锁 MECP2 的功能丧失突变引起，以及 MECP2 重复综合征，由基因重复（或三倍）引起。具有相反分子缺陷（和转录改变）的两种综合征中重叠表型的机制仍然是个谜。我的初步数据表明，MeCP2 功能的丧失和增强都会导致自发钙活性的互相关性增加，并在急性分离的海马切片中增加对 GABA 阻断的敏感性。这种超同步是由海马回路中兴奋和抑制的不平衡引起的。本提案的目的是表征RTT和MECP2重复综合征小鼠模型中海马CA1回路的功能障碍，并探索干预和挽救的可能性。我假设 MeCP2 功能的丧失和增强会在“规范”神经回路中产生类似的故障模式（电路病变），并且这些电路病变可以是 通过恢复兴奋和抑制的不平衡来挽救。为了解决这个假设，我提出了三个具体目标：（1）阐明MeCP2功能障碍导致海马CA1回路故障的细胞机制； (2)确定Mecp2突变体在学习任务期间海马CA1中的回路如何响应； (3) 确定急性或慢性改变细胞兴奋性是否可以挽救 MeCP2 疾病中的电路故障。鉴于回路功能最终决定行为，这些研究将阐明导致 Rett 综合征和 MECP2 重复综合征重叠表型的回路水平机制。它还将揭示回路对海马依赖性学习行为的反应，并揭示回路故障和行为缺陷之间的潜在相关性。这些数据将提供对电路层面操作价值的见解，并可能导致新治疗方法的设计。 K99 指导阶段（第一年和第二年）提出的研究集中于生成多个遗传小鼠系，以阐明 Mecp2 突变引起的电路故障的细胞机制，并使用微型头戴式显微镜对执行学习任务的自由移动小鼠建立体内钙成像，所有这些都将在 Huda Y. Zoghbi 博士和 Stelios 博士的监督下进行 斯米尔纳基斯。在此阶段，我将获得新技能培训，通过定期安排的每周实验室会议、导师监督和讨论会议、参加每周部门研讨会、期刊俱乐部和务虚会、参加联合实验室和合作机构，为我作为一名独立研究科学家的职业生涯做好直接准备。 会议、出席和参加国家科学会议以及参加正式课程。 R00 独立阶段（第 3 至第 5 年）将重点确定海马 CA1 回路在 Mecp2 突变体的学习任务期间如何响应，并探索 Mecp2 疾病的拯救。在此阶段，我将通过预定的电话交谈和电子邮件继续与我的导师保持积极的关系。我将依靠他们的意见和建议来招聘实验室人员、制定预算以及制定成功的 R01 拨款申请。