Function of the Six and Eya Genes in Retinal Development

描述(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依赖于进化上保守的调控回路的活动，其中包括Pax、Six、Eya和Dach基因家族的成员。对这项提议特别感兴趣的是Six和Eya蛋白在视网膜中所起的作用。这些基因家族的功能非常重要，因为选择基因的突变可以导致全前脑、双眼无眼、先天性白内障以及非视网膜缺陷，如强直性肌营养不良和分支-耳-肾综合征。此外，这些基因还与肿瘤的发生和许多癌症有关。6种蛋白质作为含有转录因子的同源盒，而Eya蛋白则作为转录共激活因子和蛋白酪氨酸磷酸酶。这些蛋白质家族通过形成六个Eya异源二聚体进行合作，这些异源二聚体被认为是下游靶基因的强大激活剂。这些异二聚体的活性是至关重要的，因为功能丧失的突变会导致人类患者和小鼠模型系统的视网膜缺陷，以及果蝇黑腹果蝇复眼的完全消除。在昆虫和哺乳动物系统中，Six和Eya基因损伤与视网膜疾病的关联为我们提供了一个令人兴奋的机会来进一步探索这些因素在视网膜发生中所起的作用。果蝇发育中的眼睛已经成为研究支配组织决定的遗传和分子机制的主要模型系统。这些优势包括已经被很好地描述的刻板印象的发育模式，关于已知眼睛规格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，眼睛缺失是Eya家族的唯一成员，Sine Oculis，Optix和DSix4代表六个基因家族。尽管在理解这些基因在发育中所扮演的角色方面已经做出了重大努力，但仍有大量重要的问题仍未得到解答。这项拟议工作的目标是解决这些问题，并提供答案，以加深我们对Six和Eya基因在视网膜决定中所起作用的理解。在这项提案中，我们将尝试确定(1)Optix在正常眼睛发育中所起的作用；(2)正弦眼球和眼睛缺失在将视网膜规范与细胞周期和组织生长联系起来中所起的作用；以及(3)正弦眼球在眼睛规范过程中转录靶标的同一性及其对其调节的影响。为了解决这些问题，我们将使用遗传学、分子和生化方法以及基因组和生物信息学方法来研究这些问题。 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在一定程度上是由包括Six和Eya基因家族成员的分子回路的活动控制的。这项工作将深入了解这些基因如何引导视觉原基内的细胞正确地采用视网膜命运。我们的研究也可能为细胞在分子水平上对Six和Eya基因的丢失做出何种反应提供线索。

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.