Developmental functions of insect Dbf4 link replication and transcription

昆虫Dbf4的发育功能将复制和转录联系在一起细胞每次分裂时都会复制它们的DNA，这个过程受到真菌、昆虫和其他动物中发现的特殊蛋白质的精心控制。在昆虫中，DNA复制的关键调控因素之一已经进化出第二个重要的作用，即对染色体蛋白质进行化学修饰。这个项目试图了解这两种功能如何以及为什么在单个基因中结合，因为这可以提供一种机制来协调DNA复制和其他染色体过程。从长远来看，这项研究可以确定杀虫剂的新靶标，还可以加强我们对DNA复制和基因表达在不同生物体中如何控制和协调的理解。研究生将作为该项目的一部分接受培训，该项目还提供基于本科课程的研究经验(CURE)。这种疗法的目的是让本科生在大学生涯中尽早获得真实的研究经验，以提高他们的学习成绩，保持科学，技术，工程和数学(STEM)，并提高他们的实验室研究技能。DNA复制是由两个激酶CDK和CDC7的作用启动的，这两个激酶都需要调节亚基的结合才能激活。DBF4是CDC7的调节亚单位，其中任何一个亚基的缺失都会扰乱从酵母到哺乳动物的生物体中的DNA复制和有丝分裂。以前的研究表明，雪纺是果蝇中唯一可识别的Dbf4同系物，它结合并激活果蝇CDC7(DCDC7)。与dCdc7不同，dcc7对DNA复制和活性是必不可少的，而雪纺的dCdc7结合活性不是发育所必需的。相反，雪纺具有第二个复制无关的功能，这是必不可少的；它结合Gcn5，并形成昆虫特异性的组蛋白乙酰转移酶复合体，雪纺组蛋白乙酰转移酶(ChAT)。令人惊讶的是，在发育过程中，ChAT可以取代功能良好的Gcn5转录共激活因子SPT-Ada-Gcn5乙酰转移酶(SAGA)。由于SAGA的组蛋白乙酰转移酶活性刺激转录，本项目的假设是ChAT的组蛋白乙酰化对于果蝇生长发育所必需的基因的正确转录激活是必要的。该项目将识别需要ChAT才能正常基因表达的基因，表征ChAT在全基因组的分布，并探索控制DDK和ChAT复合体特定细胞类型表达的机制。总体而言，这些研究将提供对基因组复制、染色质修改和转录的动态和时空协调的洞察。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Developmental functions of insect Dbf4 link replication and transcriptionCells copy their DNA each time they divide in a process that is carefully controlled by specialized proteins that are found in fungi, insects, and other animals. In insects, one of these key regulators of DNA replication has evolved a second essential role to chemically modify chromosomal proteins. This project seeks to understand how and why these two functions are combined within a single gene, since this could provide a mechanism to coordinate DNA replication with other chromosomal processes. In the long term, this research could identify novel targets for insecticides, and could also enhance our understanding of how DNA replication and gene expression are controlled and coordinated in different organisms. Graduate students will be trained as part of this project, which also provides an undergraduate course-based research experience (CURE). This CURE aims to involve undergraduate students in authentic research experiences as early as possible during their university career to enhance their academic performance, retention in Science, Technology, Engineering and Math (STEM), and improve their laboratory research skills.DNA replication is initiated by the action of two kinases, CDK and Cdc7, which both require binding of regulatory subunits for activity. Dbf4 is the regulatory subunit for Cdc7, and loss of either of these subunits disrupts DNA replication and mitosis in organisms from yeast to mammals. Previous studies showed that Chiffon, the single identifiable Dbf4 homolog in Drosophila, binds and activates Drosophila Cdc7 (dCdc7). In contrast to dCdc7, which is essential for DNA replication and viability, the dCdc7-binding activity of Chiffon is not required for development. Instead, Chiffon has a second replication-independent function that is essential; it binds Gcn5 and nucleates formation of an insect-specific histone acetyltransferase complex, Chiffon Histone Acetyltransferase (CHAT). Surprisingly, CHAT can substitute for the well characterized Gcn5 transcriptional coactivator Spt-Ada-Gcn5 acetyltransferase (SAGA) during development. Since the histone acetyltransferase activity of SAGA stimulates transcription, the hypothesis of this project is that histone acetylation by CHAT is necessary for proper transcription activation of genes that are essential for Drosophila growth and development. This project will identify genes that require CHAT for proper gene expression, characterize the genome-wide distribution of CHAT, and explore the mechanisms that control cell type-specific expression of the DDK versus CHAT complexes. Overall, these studies will provide insight into the dynamics and spatiotemporal coordination of genome replication, chromatin modification and transcription.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.