The Role of Cyclin A in Cardiac Development

细胞周期蛋白 A 在心脏发育中的作用

• 批准号: 6756528
• 负责人: Hina W Chaudhry
• 金额: $ 12.89万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-15 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6756528
• 关键词: age difference; apoptosis; cardiac myocytes; cell proliferation; cyclin dependent kinase; cyclins; gene induction /repression; genetically modified animals; growth /development; heart; heart enlargement; laboratory mouse

DESCRIPTION (provided by applicant): This is an application for a Mentored Physician Scientist Development Award for Hina W. Chaudhry, M.D. who will be an assistant professor of clinical medicine as of July 1, 2000. She will spend 80 percent of her time in a program of scientific training under the guidance of Dr. Debra Wolgemuth, Professor of Genetics and Development. This training will be driven by a project whose theme is to investigate the role of cyclin A in cardiomyocyte development proliferation, and terminal differentiation. The first specific aim is based on a transgenic mouse model of constitutive cyclin A expression in the heart. This is based on the observation that cyclin A levels in the heart drop precipitously shortly after birth in mice, rats, and humans, coincident with terminal differentiation of the heart. The mouse model has been generated based on the hypothesis that constitutive expression will maintain proliferation through the later phases of development, the neonatal period, and adulthood. The phenotype of these mice will be characterized with respect to heart size, cardiomyocyte hyperplasia/hypertrophy, altered cardiac function, an increase in nuclear ploidy and DNA synthesis, alteration of expression of other cell cycle proteins, apoptosis, and an altered response to injury. The second specific aim seeks to characterize molecular events that occur downstream of cyclin A binding to its kinase partners, cdk2 and cdc2. This is based on the hypothesis that cardiomyocyte cell cycle exit is coordinated by a cascade of inhibition whereby down regulation of cyclin A results in hypophosphorylation of RB or an RB-hke protein, and that constitutive expression of cyclin A in the heart may result in the maintenance of a phosphorylated state of such a protein, thereby resulting in persistent transcription of genes responsible for DNA replication and cell division. The third specific aim seeks to understand the mechanism underlying the down regulation of cyclin A in the heart. Methylation of promoter sequences is a well-established epigenetic modification that can result in gene silencing. Sequences of the cyclin A promoter thought to be crucial for gene transcription will by assayed for methylation and a potential correlation with cell cycle exit will be explored. The pursuit of these specific aims will provide the critical focus during which time the PI will gain an intensive training experience, learning new techniques as well as the methods of scientific inquiry under the immediate supervision of the Sponsor, an internationally recognized expert in the field of cell cycle and developmental biology. In addition to daily interactions with the Sponsor and members of the immediate laboratory, the PI will participate in a series of lectures given by the faculty of Genetics and Development, and participate in seminars through the Department of Medicine. Additionally, the Sponsor holds a series of Work-in-Progress seminars, in which members of the laboratory present intermediate data and receive critical suggestions from other laboratory members and invited faculty. These intellectual resources, combined with the fiscal resources to support theproject which will be provided by the Chairman of Medicine, will enable the PI to develop into an independent investigator by the conclusion of the training period.

描述（由申请人提供）：这是 Hina W. Chaudhry 医学博士的导师医师科学家发展奖申请，她将担任临床助理教授 自 2000 年 7 月 1 日起，她将从事医学工作。她将把 80% 的时间花在遗传学与发育教授 Debra Wolgemuth 博士的指导下的科学培训计划上。该培训将由一个项目驱动，该项目的主题是研究细胞周期蛋白 A 在心肌细胞发育、增殖和终末分化中的作用。 第一个具体目标是基于心脏中组成型细胞周期蛋白 A 表达的转基因小鼠模型。这是基于以下观察结果：小鼠、大鼠和人类出生后不久，心脏中的细胞周期蛋白 A 水平急剧下降，这与心脏的终末分化相一致。该小鼠模型是基于这样的假设而产生的：组成型表达将在发育后期、新生儿期和成年期维持增殖。这些小鼠的表型特征包括心脏大小、心肌细胞增生/肥大、心脏功能改变、核细胞增多等。 倍性和 DNA 合成、其他细胞周期蛋白表达的改变、细胞凋亡以及对损伤的反应改变。 第二个具体目标旨在描述细胞周期蛋白 A 与其激酶伙伴 cdk2 和 cdc2 结合下游发生的分子事件。这是基于这样的假设：心肌细胞细胞周期的退出是通过级联抑制来协调的，由此细胞周期蛋白 A 的下调导致 RB 或 RB-hke 蛋白的低磷酸化，并且组成型 细胞周期蛋白 A 在心脏中的表达可能会导致这种蛋白质磷酸化状态的维持，从而导致负责 DNA 复制和细胞分裂的基因持续转录。 第三个具体目标旨在了解心脏中细胞周期蛋白 A 下调的机制。启动子序列的甲基化是一种公认​​的表观遗传修饰，可导致基因沉默。被认为对基因转录至关重要的细胞周期蛋白 A 启动子序列将通过甲基化分析以及与 将探讨细胞周期退出。 对这些具体目标的追求将提供关键焦点，在此期间，PI 将获得强化培训经验，在赞助商（细胞周期和发育生物学领域国际公认的专家）的直接监督下学习新技术和科学探究方法。除了与申办者和直接实验室成员的日常互动外，PI还将参加遗传学与发育学院举办的一系列讲座，并参加医学系的研讨会。此外，主办方还举办了一系列正在进行的研讨会，实验室成员在研讨会上展示中间数据并接受其他实验室成员和受邀教师的批评建议。这些智力资源，加上医学主席将提供的支持该项目的财政资源，将使 PI 能够在培训期结束时发展成为一名独立研究者。