Genetic Control of Axial Patterning in Drosophila Eye

描述（由申请人提供）：在器官发生期间，轴向图案对于生长和发育是必不可少的。果蝇为研究眼原基的背腹纹和生长提供了理想的模型。DV图案是在眼睛中形成的第一个轴。我们的目标是确定参与早期眼睛模式的关键基因。在早期的眼成虫盘中，DV模式化是通过背选择基因pannier（pnr）的表达启动而建立的，pnr控制无翅（wg）信号基因和易洛魁族转录因子的表达。背侧基因拮抗腹侧基因Lobe（L）、Serrate（Ser）和fringe（fng）的功能。这两组基因的相互作用导致在DV边界处优先激活Notch信号传导以诱导生长和分化。需要解决的主要问题之一是这种调控相互作用的分子遗传基础。在腹侧结构域中，Notch配体Serrate（Ser）和新蛋白Lobe（L）起关键作用。L在背侧和腹侧结构域中表达，但仅作为Notch信号通路的组成部分为腹侧眼生长所需。L是腹眼发育、生长和存活所必需的。为了理解L在细胞存活、特化和生长中功能的分子遗传学基础，我们将使用果蝇模型系统中常用的分子遗传学方法来分析（i）L和Homothorax（Hth）（眼发育的负调节剂）在控制眼生长中的功能（ii）L在视网膜细胞命运决定和分化中的功能，以及（iii）L和Cullin-4的功能，一种E3泛素连接酶，控制腹侧眼细胞的存活。这些研究将有助于阐明参与L介导的Notch通路调节细胞存活、生长和模式的遗传电路。这里研究的大多数基因是高度保守的，因为它们存在于包括人类在内的高等哺乳动物中，DV图案的遗传控制是哺乳动物眼睛发育过程中的重要事件。这项研究将有助于揭示早期眼睛发育中的遗传相互作用机制。因此，我们的研究也将有助于了解哺乳动物的眼睛发育和儿童早期视网膜疾病的病因。 公共卫生相关性：轴向图案化是多细胞生物体中器官发生的基本过程，涉及单层上皮向三维器官的转变。一个完善的果蝇（果蝇）模型将被用来研究背腹（DV）（轴向）图案和发育中的眼睛的生长。DV图案化是眼睛中发生的第一个谱系限制事件，导致眼睛的背侧和腹侧域的形成。眼的背侧和腹侧区域之间的边界是Notch（N）信号通路的位点，其调节眼的细胞增殖和分化。我们将试图了解果蝇早期眼盘发育过程中DV模式和生长的遗传机制。DV边界是由背侧选择基因和腹侧选择基因的相互作用建立的。背侧因子包括GATA家族转录因子Pannier（Pnr）、分泌的形态发生蛋白Wingless（Wg）和易洛魁族（Iro-C）家族同源框蛋白。在腹侧结构域中，Notch配体Serrate（Ser）和新蛋白Lobe（L）起关键作用。L在背侧和腹侧结构域中表达，但仅作为Notch信号通路的组成部分为腹侧眼生长所需。果蝇的眼睛开始于一个腹侧的等效状态，在此基础上建立了背侧的命运。其中一个重要的问题是，眼睛最初的腹侧命运是如何建立和维持的。我们早期的研究表明，L是腹眼发育，生长和生存所必需的。为了理解L在细胞存活、特化和生长中功能的分子遗传学基础，我们将使用果蝇模型系统中常用的分子遗传学方法来分析（i）L和Homothorax（Hth）（眼发育的负调节剂）在控制眼生长中的功能（ii）L在视网膜细胞命运决定和分化中的功能，以及（iii）L和Cullin-4的功能，一种E3泛素连接酶，控制腹侧眼细胞的存活。这些研究将有助于阐明参与L介导的Notch通路调节细胞存活、生长和模式的遗传电路。由于遗传机制是高度保守的，将信息外推到高等脊椎动物将是有趣的。这些研究将有助于了解器官发生过程中早期发育事件的遗传机制。参与轴向模式的遗传机制在整个物种中是高度保守的。在人类和其他脊椎动物中，视网膜的DV极性将视网膜轴突投射引导到大脑。这些研究将阐明早期发育事件的作用，可能会影响视网膜轴突投射到大脑。这也将有助于理解果蝇的人类同源基因突变引起的发育缺陷的分子基础。

DESCRIPTION (provided by applicant): During organogenesis axial patterning is essential for growth and development. The fruit fly, Drosophila, provides an ideal model for genetic analysis of dorsoventral (DV) patterning and growth of the eye primordium. DV patterning is the first axis formed in eye. Our goal is to identify key genes involved in early eye patterning. In early eye imaginal disc, the DV patterning is established by initiation of expression of a dorsal selector gene, pannier (pnr), which controls the expression of wingless (wg) signaling gene and Iroquois family transcription factors. The dorsal genes antagonize the function of ventral genes including Lobe (L), Serrate (Ser) and fringe (fng). The interaction of these two groups of genes leads to preferential activation of Notch signaling at the DV border to induce growth and differentiation. One of the major questions that need to be addressed is the molecular genetic basis for such regulatory interactions. In the ventral domain, a Notch ligand Serrate (Ser) and a novel protein Lobe (L) play key roles. L is expressed in both dorsal and ventral domains but is only required for ventral eye growth as a component of Notch signaling pathway. L is required for ventral eye development, growth, and survival. To understand the molecular genetic basis of L functions in cell survival, specification and growth, we will use molecular genetics approaches commonly employed in Drosophila model system to analyze (i) the function of L and Homothorax (Hth), a negative regulator of eye development, in the control of eye growth (ii) the L function in retinal cell fate determination and differentiation, and (iii) function of L and Cullin-4, an E3 ubiquitin ligase, in the control of ventral eye cell survival. These studies will help to elucidate the genetic circuitry involved in L mediated Notch pathway regulation of cell survival, growth, and patterning. Most of the genes studied here are highly conserved as they are present in higher mammals including humans, and genetic control of DV patterning is an important event during mammalian eye development. This study will help in revealing mechanisms of genetic interactions involved in early eye development. Thus, our study will also contribute to the understanding of mammalian eye development and etiology of early childhood retinal diseases. PUBLIC HEALTH RELEVANCE: Axial patterning, a fundamental process of organogenesis in multi-cellular organisms, involves transition of a mono-layered epithelium to a three- dimensional organ. A well established model of the Drosophila melanogaster (fruit fly) will be employed to study dorso-ventral (DV) (axial) patterning and growth in the developing eye. DV patterning, the first lineage restriction event occurring in the eye, results in the formation of dorsal and ventral domains of the eye. The border between the dorsal and ventral domains of the eye is the site of Notch (N) signaling pathway which regulates cell proliferation and differentiation of the eye. We will try to understand the genetic mechanism of DV patterning and growth during early eye imaginal disc development in Drosophila. The DV boundary is established by interactions of dorsal selector genes and ventral genes. The dorsal factors include a GATA-family transcription factor Pannier (Pnr), the secreted morphogen Wingless (Wg), and Iroquois (Iro-C) family homeobox proteins. In the ventral domain, a Notch ligand Serrate (Ser) and a novel protein Lobe (L) play key roles. L is expressed in both dorsal and ventral domains but is only required for ventral eye growth as a component of Notch signaling pathway. The Drosophila eye begins from a ventral equivalent state on which dorsal fate is established. One of the important questions is how the initial ventral fate of the eye is established and maintained. Our earlier studies have demonstrated that L is required for ventral eye development, growth, and survival. To understand the molecular genetic basis of L functions in cell survival, specification and growth, we will use molecular genetics approaches commonly employed in Drosophila model system to analyze (i) the function of L and Homothorax (Hth), a negative regulator of eye development, in the control of eye growth (ii) the L function in retinal cell fate determination and differentiation, and (iii) function of L and Cullin-4, an E3 ubiquitin ligase, in the control of ventral eye cell survival. These studies will help to elucidate the genetic circuitry involved in L mediated Notch pathway regulation of cell survival, growth, and patterning. Since the genetic machinery is highly conserved it will be interesting to extrapolate the information to higher vertebrates. These studies will contribute towards understanding the genetic mechanism of early developmental events during organogenesis. The genetic machinery involved in axial patterning is highly conserved across the species. In humans and other vertebrates, DV polarity of the retina directs the retinal axon projections to the brain. These studies will shed light on the role of early developmental events that may affect the retinal axon projection to the brain. It will also help to understand the molecular basis of developmental defects caused by mutations in the human homolog of Drosophila.