Mechanism of Differentiation Functions of Cyclin Dependent Kinase 6 (Cdk6)

描述(申请人提供)：这里提出的实验旨在研究细胞周期蛋白依赖性激酶6(CDK6)阻断分化的机制，旨在了解CDK6在分化和肿瘤发生中的作用。这些实验方法旨在加强对胶质母细胞瘤发生机制的了解。胶质母细胞瘤是最常见和最致命的恶性胶质瘤类型[巴克胡，2002#2]；胶质瘤占所有原发脑肿瘤的一半以上{Dai，2001#4}。CDK6蛋白已被发现在这些肿瘤中过表达(Costello，1997#1；Lam，2000#3)。这里提出的实验主要是在星形胶质细胞中进行的，星形胶质细胞是一种分化的胶质细胞，已被证明是原发脑瘤的来源。拟议的实验旨在确定CDK6的已知底物视网膜母细胞瘤肿瘤抑制蛋白是否需要实现先前特征的形态变化、祖细胞标志物的表达和增强的运动性，这些都与CDK6在小鼠星形胶质细胞中的表达有关。还建议进行实验，以确定CDK6(Cdk6NFG)的激酶缺陷突变是否会导致这些变化。第三组实验旨在研究CDK6磷酸化分化特异性转录因子以调节其功能，从而调控分化过程的假说。这一假设是基于在酵母双杂交筛选中发现CDK6与几个转录因子结合的发现。这些实验将确定CDK6是否与转录因子结合和/或磷酸化以调节它们的功能。该项目支持NCI的使命，即通过研究已知癌基因的功能，了解细胞迁移的机制，促进我们对癌症的理解，这两个方面对理解胶质瘤都很重要。该项目还将通过让本科生接触到高质量的癌症研究来教育和培训未来的癌症研究人员。在研究人员实验室进行研究的学生中，100%都进入了研究生学习、专业学习或科学职业生涯。事实上，数据显示，文科院校培养的最终博士几乎是其他本科院校的两倍。建议的实验是由本科生直接与校长调查员合作进行的，目的是为了实现上述目标。Grossel这项建议中概述的实验旨在了解细胞周期调节蛋白和已知的癌基因--细胞周期蛋白依赖激酶6--如何在细胞分化过程中发挥作用。CDK6的这种功能将在星形细胞中进行研究，星形细胞是一种有可能成为胶质母细胞瘤的细胞，胶质母细胞瘤是最常见和最致命的胶质瘤类型。

DESCRIPTION (provided by applicant): The experiments proposed here are aimed at investigating the mechanism of cyclin dependent kinase 6 (cdk6) in blocking differentiation and are designed to understand cdk6 function in differentiation and oncogenesis. These experimental approaches aim to enhance understanding of the mechanisms involved in the genesis of glioblastomas. Glioblastoma is the most common and lethal type of malignant glioma {Bachoo, 2002 #2}; gliomas comprise more than half of all primary brain tumors {Dai, 2001 #4}. The cdk6 protein has been found to be overexpressed in these tumors {Costello, 1997 #1; Lam, 2000 #3}. The experiments proposed here are primarily conducted in astrocytes, a type of differentiated glia from which primary brain tumors have been shown to originate {Bachoo, 2002 #2}. Proposed experiments aim to determine if the retinoblastoma tumor-suppressor protein, a known substrate of cdk6, is required to achieve previously characterized changes in morphology, expression of progenitor cell markers, and enhanced motility that have all been associated with cdk6 expression in mouse astrocytes. Also proposed are experiments designed to determine if a kinase-defective mutant of cdk6 (cdk6NFG) will cause these changes. The third set of experiments is designed to investigate the hypothesis that cdk6 phosphorylates differentiation-specific transcription factors to regulate their function, thereby regulating the process of differentiation. This hypothesis is based on the finding that cdk6 was found to bind several transcription factors in a yeast two- hybrid screen. These experiments will determine if cdk6 binds to and/or phosphorylates transcription factors to regulate their function. This project supports the mission of the NCI in that is advances our understanding of cancer, by investigating the function of a known oncogene, understanding mechanisms of cell migration, both important to the understanding of gliomas. This project will also educate and train future cancer researchers by exposing undergraduate students to high-quality cancer research. One-hundred percent of the students that have conducted research in the investigator's lab have gone on to graduate studies, professional studies, or careers in science. Indeed, data shows that liberal arts colleges produce almost twice as many eventual Ph.D.s as do other baccalaureate institutions {Connell, 2004 #7; Foundation, 1996 #6}. The experiments proposed are designed to be conducted by undergraduate students working directly with the Principle Investigator on the aims outlined above. Grossel The experiments outlined in this proposal aim to understand how a cell cycle regulatory protein and known oncogene, cyclin dependent kinase 6, functions in the process of cellular differentiation. This function of cdk6 will be studied in astroctyes, a type of glial cell that has the potential to become a glioblastoma, the most common and lethal type of glioma.