Engrailed genes and cerebellum morphology, spatial gene expression and circuitry

描述（由申请人提供）：越来越多的证据表明，大脑的许多区域，包括小脑，都涉及自闭症谱系障碍（ASD）。小脑不仅在熟练的运动表现中起着关键作用，而且各种研究表明它与非运动活动有关，包括语言。一个等位基因系列的小鼠Engrailed（En）突变体显示小脑的形态缺陷和传入通路的地形破坏。因此，更好地了解En 1/2如何调节小脑发育，应提供深入了解人类小脑畸形综合征与肉眼形态学变化，以及疾病，如ASD与更微妙的形态异常，但可能有显着的小脑回路功能障碍。ASD和En基因之间的另一个可能联系是与自闭症相关的人类EN 2的RFLP。此外，En 2突变小鼠在社会互动方面存在缺陷。一个新的全球性的方法来研究小脑是需要涉及到它是如何组织在形态学水平，模式化的基因表达和功能特异性传入通路，因为模式的叶和parasophylla基因表达反映了每个传入通路的地形。此外，叶状结构的区域差异反映了功能的专门化，因为哺乳动物的小脑沿着内侧-外侧轴沿着分为主要容纳运动回路的中央蚓部和主要容纳小脑神经回路的周围半球。En基因将被用作遗传切入点，以确定在遗传和细胞水平上parasoprotein基因表达和叶状是如何形成的，以便深入了解小脑电路是如何形成的。此外，下游效应将被确定为介导这些过程，因此可能是候选小脑疾病基因。由于基本的叶状模式和parasophylla基因表达在哺乳动物中是保守的，我们在小鼠中的发现应该为评估人类小脑发育和疾病提供基础。具体目标是：1）研究En 1/2如何调节蚓部和半球中不同的叶状模式，以及模式化的副纤毛基因表达和苔藓纤维地形，通过：i）通过分析时间和细胞类型特异性En 1/2条件敲除突变体，鉴定负责模式化叶状、基因表达和传入地形的关键阶段和细胞类型。ii）通过检查En 1/2条件性功能丧失和获得突变体中的浦肯野细胞和颗粒细胞扩增和迁移、空间基因表达和传入发育来鉴定由En 1/2调节的细胞过程。2)鉴定和测试候选基因，包括Eph/Ephrin，其在两个坐标系的模式化和/或建立传入拓扑结构中在En 1/2下游具有作用：i）鉴定在En 2阳性或En 2阴性细胞中差异表达的基因，其由En 1/2调节。ii）改变候选基因和Eph/Ephrin在发育中的浦肯野细胞或颗粒细胞中的表达。公共卫生相关性：小脑整合信息，如四肢和身体运动的位置，速度和力量，所有这些都是进行平稳，协调运动所必需的。它还涉及语言等认知功能。更好地了解Engrailed（En）基因突变如何导致一系列小脑形态缺陷以及神经回路中断，应提供新的原则，以帮助解释涉及小脑大小减少的人类疾病，以及自闭症谱系障碍（ASD）等疾病那里有更微妙的结构变化，但仍然可能有严重的神经回路功能障碍。

DESCRIPTION (provided by applicant): There is mounting evidence that many regions of the brain, including the cerebellum, are involved in autism spectrum disorder (ASD). The cerebellum not only plays a critical role in skilled motor performance, but a variety of studies have implicated it in non-motor activities, including language. An allelic series of mouse Engrailed (En) mutants display both morphological defects in the cerebellum and topographic disruptions of afferent pathways. A better understanding of how En1/2 regulate cerebellum development should therefore provide insight into human cerebellum malformation syndromes with gross morphological changes, as well as diseases such ASD with more subtle morphological abnormalities but that could have significant cerebrocerebellar circuit dysfunction. An additional possible link between ASD and the En genes is RFLPs of human EN2 that are associated with autism. Also, En2 mutant mice have deficits in social interactions. A new global approach to studying the cerebellum is needed to relate how it is organized at the level of morphology, patterned gene expression and functionally specific afferent pathways, because the pattern of the folia and parasagittal gene expression reflects the topography of each afferent pathway. Furthermore, regional differences in foliation reflect functional specializations, as the mammalian cerebellum is segregated along the medial-lateral axis into a central vermis housing mainly motor circuits and surrounding hemispheres housing mainly cerebrocerebellar circuits. The En genes will be used as a genetic entry point to determine how parasagittal gene expression and foliation are patterned at the genetic and cellular levels in order to gain insight into how cerebellum circuitry is laid down. In addition, downstream effectors will be identified that mediate these processes and thus that could be candidate cerebellum disease genes. Since the basic foliation pattern and parasagittal gene expression is conserved across mammals, our findings in mice should provide a foundation for assessing human cerebellum development and disease. The Specific aims are: 1) Study how En1/2 regulate the distinct foliation patterns in the vermis and hemispheres, and also pattern parasagittal gene expression and mossy fiber topography by: i) Identifying the critical stages and cell types responsible for patterning foliation, gene expression and afferent topography by analyzing temporal and cell type specific En1/2 conditional knock-out mutants. ii) Identifying cellular processes regulated by En1/2 by examining Purkinje cell and granule cell expansion and migration, spatial gene expression and afferent development in En1/2 conditional loss- and gain-of-function mutants. 2) Identify and test candidate genes including Eph/Ephrins that have roles downstream of En1/2 in patterning the two coordinate systems and/or establishing afferent topography by: i) Identifying genes differentially expressed in En2 positive or En2 negative cells that are regulated by En1/2. ii) Altering expression of candidate genes and Eph/Ephrins in developing Purkinje cells or granule cells. PUBLIC HEALTH RELEVANCE: The cerebellum integrates information such as the position, speed and force at which the limbs and body are moving, all of which are necessary to carry out smooth, coordinated movements. It also is implicated in cognitive functions like language. A better understanding of how mutations in the Engrailed (En) genes result in a range of morphological cerebellum defects as well as disruptions of neural circuits should provide new principals to aid in the interpretation of human diseases which involve reduction in the size of the cerebellum, as well as diseases such as autism spectrum disorder (ASD) where there are more subtle structural alterations but could nevertheless have profound dysfunction of neural circuits.