Control of Actin Ring Formation During Cell Division in Aspergillus

曲霉细胞分裂过程中肌动蛋白环形成的控制

• 批准号: 9723711
• 负责人: Steven Harris
• 金额: $ 29.8万
• 依托单位: University of Connecticut Health Center
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-15 至 2001-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9723711&HistoricalAwards=false
• 关键词: Control; Actin; Ring; Formation; During

9723711 Harris In preparation for cytokinesis, both animal and fungal cells assemble a cortical actin ring. The formation of this ring appears to be temporally and spatially controlled by signals from mitotic nuclei. Current models suggest that the actin ring functions via two possible mechanisms to effect cytokinesis. In animals and certain fungi, the actin ring contracts, splitting cells in two. In other fungi, the ring defines a region where a cell plate forms to divide the cell. Regardless of mechanism used, the actin ring is essential for cytokinesis. Previous studies employing various biochemical and genetic approaches have identified numerous proteins necessary for the formation and/or function of the actin ring. However, it is not at all clear how these proteins function in an integrated manner to control cytokinesis. Moreover, it has become increasingly evident that a complete inventory of actin ring proteins has not been attained. The overall objective of Dr. Harris' research program is to use the power of genetics to identify and characterize additional proteins required for the formation and function of the actin ring, and thereby elucidate the molecular mechanisms underlying cytokinesis in the genetically tractable filamentous fungus, Aspergillus nidulans. This fungus undergoes cytokinesis by forming crosswalls known as septa. Septum formation in A. nidulans is temporally and spatially coordinated with mitosis, and requires the formation of a contractile actin ring. Genetic screens have resulted in the identification and characterization of gene products which act at different steps to control septation in A. nidulans. For example, the analysis of sepB mutants has revealed the existence of a checkpoint which prevents septum formation in the presence of DNA damage. In contrast, the characterization of sepA mutants has led to the identification of an evolutionarily conserved protein that may control the assembly of the actin ring. The objective of this research project is to address the hypothesis that the sepA gene product plays an essential role in septum formation by promoting the formation of the contractile actin ring. Specifically, Dr. Harris will use indirect immunofluorescence to determine if SepA localizes to the incipient division site. In addition, he will establish the timing of SepA localization relative to mitosis and actin ring formation. He also plans to employ a battery of genetic and biochemical approaches to identify proteins that interact with SepA. In particular, he will test predictions that SepA function requires interactions with the actin-associated protein profilin and with the septins. The fascinating process of cytokinesis, in which a living cell literally separates itself into two progeny cells, underpins the nature of life. This research project should lead to a better understanding of the general mechanisms underlying cytokinesis. The use of a filamentous fungus as the model organism in this study is a particularly good choice because of the pronounced societal impact of fungi. On the one hand, some fungi cause diseases; on the other hand, they produce useful natural products such as antibiotics and commercially important enzymes, and can be genetically engineered to produce non-fungal proteins of commercial interest. Thus, an increased understanding of how septum formation permits filamentous fungi to grow and reproduce can lead to ways of combating fungal infections of plants, animals, and humans, as well as allowing fungi to be used more efficiently as industrial biocatalysts for the production of commercially important enzymes and other proteins. ***

小行星9723711 在胞质分裂的准备过程中，动物和真菌细胞都装配了一个皮层肌动蛋白环。 该环的形成似乎在时间和空间上受来自有丝分裂核的信号控制。 目前的模型表明，肌动蛋白环功能通过两种可能的机制来影响胞质分裂。 在动物和某些真菌中，肌动蛋白环收缩，将细胞一分为二。 在其他真菌中，环定义了一个区域，其中细胞板形成以分裂细胞。 无论使用的机制，肌动蛋白环是必不可少的胞质分裂。 以前的研究采用各种生物化学和遗传学的方法已经确定了许多蛋白质的形成和/或功能的肌动蛋白环。 然而，目前还不清楚这些蛋白质如何以整合的方式控制胞质分裂。 此外，它已变得越来越明显，一个完整的清单肌动蛋白环蛋白尚未达到。 Harris博士研究计划的总体目标是利用遗传学的力量来识别和表征肌动蛋白环形成和功能所需的其他蛋白质，从而阐明遗传上易于处理的丝状真菌Aspergillusnidulans胞质分裂的分子机制。 这种真菌通过形成横壁（称为隔膜）进行胞质分裂。 隔形成于A. nidulans在时间和空间上与有丝分裂相协调，并且需要形成收缩性肌动蛋白环。 遗传筛选已经导致在不同步骤中控制A. nidulans。 例如，对sepB突变体的分析揭示了在存在DNA损伤的情况下防止隔膜形成的检查点的存在。 与此相反，sepA突变体的表征导致了一个进化上保守的蛋白质，可以控制肌动蛋白环的组装的鉴定。 本研究项目的目的是解决的假设，即sepA基因产物中起着至关重要的作用，通过促进形成的收缩肌动蛋白环的隔膜形成。 具体来说，Harris博士将使用间接免疫荧光法来确定SepA是否定位于初始分裂部位。 此外，他还将确定SepA定位相对于有丝分裂和肌动蛋白环形成的时间。 他还计划采用一系列遗传和生物化学方法来鉴定与SepA相互作用的蛋白质。 特别是，他将测试预测，SepA功能需要与肌动蛋白相关蛋白profilin和septins的相互作用。 细胞质分裂的迷人过程，其中一个活细胞从字面上分离成两个后代细胞，巩固了生命的本质。 这项研究项目将导致更好地了解胞质分裂的一般机制。 在这项研究中使用丝状真菌作为模式生物是一个特别好的选择，因为真菌的显著社会影响。 一方面，一些真菌会引起疾病;另一方面，它们产生有用的天然产物，如抗生素和商业上重要的酶，并且可以通过基因工程来生产具有商业价值的非真菌蛋白质。 因此，对隔膜形成如何允许丝状真菌生长和繁殖的更多理解可以导致对抗植物，动物和人类的真菌感染的方法，以及允许真菌更有效地用作工业生物催化剂，用于生产商业上重要的酶和其他蛋白质。 ***