Imaging PTEN-induced changes in adult cortical structure and function in vivo

描述（由申请人提供）：自闭症是一种严重的神经发育障碍，其特征是社交互动和沟通障碍。自闭症的发病率在过去十年中呈爆炸式增长，现在估计每166名儿童中就有1名患有某种形式的自闭症。自闭症的神经病理学原因仍然难以捉摸，尽管从同卵双胞胎的60%-92%的一致性和异卵双胞胎的0-10%的一致性可以明显看出强烈的遗传贡献。对人类群体的研究表明，与自闭症相关的基因座数量超过15个。与此建议特别相关的是磷酸酶和紧张素同源物（Pten）。这种致癌基因调节有丝分裂后神经元的生长。PTEN信号通路是调节自闭症谱系障碍易感性的两个主要通路之一。皮质Pten缺失的小鼠表现出许多与自闭症相关的特征，包括大头畸形、社交互动缺陷、社交学习受损、多动和焦虑样行为增加。许多这些缺陷是可逆的长期治疗mTOR抑制剂，雷帕霉素。在这项研究中，我们使用的小鼠在出生后6-8周开始通过cre介导的切除从皮层特异性地删除Pten基因。我们最近证明，在PTEN缺失后，皮质层2/3锥体神经元的顶端树突经历了独特的生长。这种生长将树突树的顶端扩展了1毫米以上，并增加了数百个新的树突刺。我们的目标是充分描述这些生长中的神经元在基本生理和感觉信息处理方面的任何变化。为此，我们使用双光子激光扫描显微镜来指导小鼠初级视觉皮层中生长神经元的体内全细胞贴片记录的放置。我们还使用双光子成像技术对敲除小鼠和野生型小鼠皮层的网络活动进行成像。这些研究的结果可能为开发基于理性的自闭症谱系障碍治疗方法提供靶点。

DESCRIPTION (provided by applicant): Autism is a severe neurodevelopmental disorder characterized by impairments in social interaction and communication. Rates of autism have exploded over the past decade and it is now estimated that 1 out of every 166 children exhibit some form of autism. The neuropathological cause of autism remains elusive, though a strong genetic contribution is evident from the 60%-92% concordance between monozygotic twins versus 0-10% in dizogtic twins. Research in human populations indicates that the number of loci associated with autism exceeds 15. Of specific relevance to this proposal is the phosphatase and tensin homologe (Pten). This oncogene regulates the growth of post-mitotic neurons. The PTEN signaling pathway is emerging as one of two major pathways that regulate the susceptibility to autism spectrum disorders. Mice with a cortical Pten deletion exhibit many of the characteristics associated with autism, including macrocephaly, deficits in social interactions, impaired social learning, hyperactivity, and increased anxiety-like behavior. Many of these deficits are reversible with chronic treatment of the mTOR inhibitor, rapamycin. In this proposal, we employ mice in which the Pten gene is deleted specifically from the cortex by CRE-mediated excision beginning some 6-8 weeks after birth. We recently demonstrated that cortical layer 2/3 pyramidal neurons experience a unique growth of their apical dendrites following PTEN deletion. This growth expands the apical dendritic tree by upwards of 1mm and adds hundreds of new dendritic spines. Our goal is to fully characterize any changes in basic physiology and sensory information processing in these growing neurons. To this end we use 2-photon laser scanning microscopy to guide the placement of in vivo whole cell patch recordings from growing neurons in the mouse primary visual cortex. We also use 2-photon imaging to image network activity in the cortex of knockout and wildtype mice. Results from these studies may provide targets for the development of rationally based therapeutics for autism spectrum disorders. PUBLIC HEALTH RELEVANCE: The PTEN signaling pathway is emerging as one of two major pathways that regulate the susceptibility to autism spectrum disorders. We earlier characterized robust changes in dendritic structure in conditional knockout mice. Here we measure changes in physiology and sensory processing in these growing neurons using in vivo whole cell patch recordings and 2-photon in vivo imaging of network activity.