Effects of DEAF1 on Neuronal Activity and Target Gene Expression.

 描述(申请人提供)：智力残疾的特征是认知能力低于平均水平，导致功能和适应行为的严重缺陷。大多数原因不明的智力残疾病例是由从头基因突变引起的。4名智障人士被发现在转录因子变形表皮自律因子-1(DEAF1)的DNA结合域内存在杂合点突变，由此产生的氨基酸替换被证明对DEAF1蛋白功能产生负面影响。最近从一组来自智力残疾和自闭症谱系障碍的样本中发现了另外四个DEAF1变体。这些突变也发生在DNA结合域内，但这些突变对DEAF1功能的影响目前尚不清楚。由于DEAF1单倍体蛋白的充足没有报道会导致智力残疾，这表明突变的DEAF1蛋白可能对野生型DEAF1的功能产生显性的负面影响。突变的DEAF1蛋白在导致智能障碍的发病机制中的作用机制尚不清楚。这一提议的假设是，DEAF1基因的突变降低了DEAF1蛋白的功能，导致神经元活动改变和靶基因表达的可测量变化。特定目的1将确定新发现的DEAF1突变对DEAF1蛋白功能的影响，并使用体外和体外方法评估DEAF1突变蛋白的显性负活性。特定目标2将评估DEAF1功能减弱对神经元活性/可塑性和靶基因表达的影响。在大脑中有条件地敲除Deaf1的小鼠在恐惧条件反射测试中表现出类似焦虑的行为和上下文记忆受损，并将被用来建立DEAF1在调节神经元活动中的作用。将评估在这些小鼠的海马区差异表达的与神经元和认知功能相关的DEAF1基因靶点。拟议的研究将描述已确定的人类从头DEAF1突变的功能影响，以及中枢神经系统DEAF1活性降低的后果。我们期望这些研究的结果也将为DEAF1功能失调和智力残疾之间的因果关系提供证据。

 DESCRIPTION (provided by applicant): Intellectual disability is characterized by below-average cognitive ability leading to significant deficits in functioning and adaptive behaviors. Th majority of the unexplained intellectual disability cases are caused by de novo gene mutations. Four individuals with intellectual disabilities were found to have heterozygous de novo point mutations within the DNA binding domain of the transcription factor Deformed Epidermal Autoregulatory Factor-1 (DEAF1), and the resultant amino acid substitutions were shown to negatively affect DEAF1 protein function. Four additional DEAF1 variants have recently been identified from a de-identified group of samples from individuals with intellectual disabilities an autism spectrum disorders. These mutations also occur within the DNA binding domain, but the effects of these mutations on DEAF1 function are currently uncharacterized. Since DEAF1 haploin sufficiency has not been reported to result in intellectual disabilities, this suggests tha the mutant DEAF1 proteins likely exert dominant negative influences on wildtype DEAF1 function. The underlying mechanisms by which mutant DEAF1 proteins contribute to the pathogenesis producing the intellectual disabilities remain unclear. The hypothesis for this proposal is that mutations in the DEAF1 gene that diminish DEAF1 protein function cause altered neuronal activity and measurable changes in target gene expression. Specific Aim 1 will determine the effects of newly identified DEAF1 mutations on DEAF1 protein function and also assess dominant negative activity of the DEAF1 mutant proteins using both in vitro and ex vivo approaches. Specific Aim 2 will evaluate the effects of diminished DEAF1 function on neuronal activity/plasticity and target gene expression. Mice with conditional knockout of Deaf1 in the brain show anxiety-like behavior and impaired contextual memory in fear-conditioning tests and will be used to establish a role of DEAF1 in regulating neuronal activity. DEAF1 gene targets related to neuronal and cognitive function that are differentially expressed in the hippocampus of these mice will be assessed. The proposed studies will describe the functional effects of identified human de novo DEAF1 mutations and the consequences of reduced DEAF1 activity in the central nervous system. We expect that the results of these studies will also provide evidence into the causal relationship between dysregulated DEAF1 function and intellectual disability.