Function of the Six and Eya Genes in Retinal Development

描述（由申请人提供）：包括眼睛在内的许多哺乳动物组织的早期发育部分取决于进化上保守的调节回路的活性，该调节回路包括Pax、Six、Eya和Dach基因家族的成员。该提议特别感兴趣的是Six和Eya蛋白在视网膜中发挥的作用。这些基因家族的功能非常重要，因为选择基因中的突变可导致前脑无裂畸形、双侧无眼畸形、先天性白内障以及非视网膜缺陷，如强直性肌营养不良和鳃耳肾综合征。此外，这些基因也与肿瘤发生和许多癌症有关。六种蛋白质充当含有转录因子的同源框，而Eya蛋白质充当转录共激活因子和蛋白质酪氨酸磷酸酶。这些蛋白质家族通过形成Six-Eya异二聚体而合作，这些异二聚体被认为是下游靶基因的强激活剂。这些异二聚体的活性是至关重要的，因为功能丧失突变可导致人类患者和小鼠模型系统的视网膜缺陷，以及果蝇（Drosophila melanogaster）复眼的完全消除。在昆虫和哺乳动物系统中，Six和Eya基因病变与视网膜疾病的关联为我们提供了一个令人兴奋的机会，以进一步探索这些因素在视网膜发生中发挥的作用。果蝇发育中的眼睛已经成为研究组织决定的遗传和分子机制的首要模型系统。其优势包括已被充分描述的定型发育模式、关于已知眼睛特化基因的大量实验数据以及大量可用的突变株和分子/细胞标记。在果蝇中，Eya基因家族中只有眼睛缺失基因，而sine oculis、optix和DSix 4则代表了Six基因家族。尽管已经付出了巨大的努力来理解这些基因在发育中所起的作用，但仍有大量的重要问题尚未得到解答。这项工作的目标是解决这些问题，并提供答案，这将进一步加深我们对Six和Eya基因在视网膜决定中所起作用的理解。在这个提议中，我们将试图确定（1）optix在正常眼睛发育中的作用;（2）sine oculis和眼睛缺失在将视网膜特化与细胞周期和组织生长联系起来中的作用;（3）Sine Oculis在眼睛特化过程中的转录靶点的身份及其对它们的调节的影响。为了解决这些问题，我们将使用一个创造性的混合物的遗传，分子和生物化学的方法沿着与基因组和生物信息学的方法来调查这些问题。 公共卫生相关性：包括人类视网膜在内的许多哺乳动物组织的早期发育部分受到包括Six和Eya基因家族成员的分子回路的活动的控制。这项工作将深入了解这些基因如何指导视觉原基内的细胞正确地采用视网膜的命运。我们的研究也可能提供线索，细胞如何在分子水平上对Six和Eya基因的丢失做出反应。

DESCRIPTION (provided by applicant): The early development of a number of mammalian tissues including the eye depends in part upon the activity of an evolutionarily conserved regulatory circuit that includes members of the Pax, Six, Eya and Dach gene families. Of particular interest to this proposal is the role that the Six and Eya proteins play in the retina. The function of these gene families are highly significant as mutations in select genes can lead to holoprosencephaly, bilateral anophthalmia, congenital cataracts as well as non-retinal defects such as myotonic dystrophy and branchio-oto-renal syndrome. Furthermore, these genes are also implicated in tumorigenesis and numerous cancers. Six proteins serve as homeobox containing transcription factors while Eya proteins function as transcriptional co- activators and as protein tyrosine phosphatases. These protein families cooperate by forming Six-Eya heterodimers that are thought to function as strong activators of downstream target genes. The activity of these heterodimers is crucial as loss-of-function mutations can lead to retinal defects in human patients and mouse model systems as well as total elimination of the compound eyes of the fruit fly, Drosophila melanogaster. The association of Six and Eya gene lesions with retinal disorders in both insect and mammalian systems provides us with an exciting opportunity to further explore the roles that these factors play in retinogenesis. The developing eye of the fruit fly has become a premier model system for studying the genetic and molecular mechanisms that govern tissue determination. The advantages include a stereotyped mode of development that has been well described, a large body of experimental data on known eye specification genes and a vast array of available mutant strains and molecular/cellular markers. In Drosophila, eyes absent is the sole member of the Eya family while sine oculis, optix and DSix4 represent the Six gene family. Despite the significant efforts that have been placed on understanding the roles that these genes play in development there are a large number of important questions that still remain unanswered. The goals of the proposed work are to address these questions and provide answers that will further our understanding of role played by Six and Eya genes in retinal determination. In this proposal we will attempt to determine (1) the role that optix plays in normal eye development; (2) the part that sine oculis and eyes absent plays in linking retinal specification to the cell cycle and tissue growth; and (3) the identity of the transcriptional targets of Sine Oculis during eye specification and the influence that it has on their regulation. In order to address these issues we will use a creative mixture of genetic, molecular and biochemical approaches along with genomic and bioinformatic methods to investigate these issues. PUBLIC HEALTH RELEVANCE: The early development of many mammalian tissues including the human retina is governed in part by the activities of a molecular circuit that includes members of the Six and Eya gene families. This work will yields insights into how these genes guide cells within the visual primordium to correctly adopt a retinal fate. Our studies may also provide clues to how cells react at the molecular level to the loss of the Six and Eya genes.