Developmental functions of insect Dbf4 link replication and transcription

昆虫Dbf4的发育功能连接复制和转录细胞每次分裂时复制DNA，这一过程是由真菌、昆虫和其他动物体内发现的特殊蛋白质精心控制的。在昆虫中，这些DNA复制的关键调节因子之一已经进化出了第二个重要作用，即化学修饰染色体蛋白质。该项目旨在了解这两种功能是如何以及为什么在单个基因中结合在一起的，因为这可能提供一种机制来协调DNA复制与其他染色体过程。从长远来看，这项研究可以确定杀虫剂的新靶点，也可以增强我们对不同生物中DNA复制和基因表达如何被控制和协调的理解。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）。这个CURE旨在让本科生在他们的大学生涯中尽早参与真实的研究经历，以提高他们的学习成绩，保留科学、技术、工程和数学（STEM），并提高他们的实验室研究技能。DNA复制是由两种激酶CDK和Cdc7启动的，这两种激酶都需要结合调控亚基才能发挥活性。Dbf4是Cdc7的调控亚基，从酵母到哺乳动物，这些亚基中的任何一个缺失都会破坏DNA复制和有丝分裂。先前的研究表明，Chiffon是果蝇中唯一可识别的Dbf4同源物，可以结合并激活果蝇Cdc7 （dCdc7）。dCdc7是DNA复制和生存所必需的，而雪纺的dCdc7结合活性不是发育所必需的。相反，雪纺有第二个与复制无关的功能，这是必不可少的；它结合Gcn5并形成昆虫特异性组蛋白乙酰转移酶复合物，Chiffon组蛋白乙酰转移酶（CHAT）。令人惊讶的是，CHAT可以在发育过程中替代表征良好的Gcn5转录辅助激活剂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适当转录激活是必要的。该项目将确定需要CHAT进行适当基因表达的基因，表征CHAT的全基因组分布，并探索控制DDK与CHAT复合物的细胞类型特异性表达的机制。总的来说，这些研究将为基因组复制、染色质修饰和转录的动态和时空协调提供见解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.