REGULATION OF CELLULAR PROLIFERATION AND DIVERSITY IN DROSOPHILA

果蝇细胞增殖和多样性的调控

• 批准号: 6290202
• 负责人: JAMES A. KENNISON
• 金额: --
• 依托单位: EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6290202
• 关键词: Drosophilidae; cell growth regulation; cell proliferation; developmental genetics; gene induction /repression; genetic models; homeobox genes; model design /development; nucleic acid sequence; transcription factor

Genes involved in the determination and differentiation of segmental identity in Drosophila melanogaster have been identified by genetic interactions with the homeotic genes already known to be required. Many new genes required for transcriptional activation or repression of the homeotic genes have been identified. We have cloned two of the genes required for transcriptional activation and characterized their developmental functions in more detail. One of the genes that we identified as a transcriptional activator of the homeotic genes, the kismet gene, encodes a family of large nuclear proteins. Maternally-encoded kismet proteins are ubiquitous at the blastoderm stage and are required for proper segmentation of the embryo. After gastrulation, zygotically-encoded kismet proteins accumulate to the highest levels in the brain and central nervous system. The kismet proteins all have a common carboxyl-terminal domain of about 200 kilodaltons. Within this common region is a 41 amino acid domain, the BRK domain, which is also present in the brahma protein, a subunit of a chromatin-remodeling complex also required for transcriptional activation of homeotic genes. Diversity among kismet proteins is generated by the use of alternative 5 exons encoding different amino-terminal extensions. Two major classes of kismet proteins have been identified during embryogenesis. The smaller class proteins are about 230 kilodaltons in size, while the larger class are greater than 500 kilodaltons in size. In addition to the BRK domain conserved between kismet and brahma, the larger kismet proteins have another domain conserved in the brahma protein, a DNA-stimulated ATPase domain found in several subunits of chromatin-remodeling factors. The most closely-related proteins to kismet are the CHD family proteins, which have two chromodomains (also found in the larger kismet proteins) in addition to the DNA- stimulated ATPase domain. Last year we showed that another CHD family protein in Drosophila, dMi-2, is involved in silencing homeotic genes. We have also continued our characterization of the osa gene, which is also required for transcriptional activation of homeotic genes in Drosophila. Osa encodes a large nuclear protein with homology to the yeast SWI1 protein. The yeast SWI1 protein is part of a chromatin-remodeling complex that includes homologues of two other proteins that we have previously studied, the Drosophila brahma and moira proteins. We have shown that one of the alternative promoters of the Antennapedia homeotic gene requires high levels of osa, brahma, and moira proteins, and that mutations in these three genes show strong genetic interactions. In addition, we have isolated mutations in several other genes that interact with these proteins in regulating transcription from this Antennapedia promoter. We are currently cloning two of the new genes identified in these genetic screens. - Drosophila, homeotic, transcription, brahma, kismet, osa, moira

通过与已经已知所需的同源基因的遗传相互作用，已经鉴定出参与果蝇中分段身份确定和分化的基因。已经确定了转录激活或抑制同源基因所需的许多新基因。我们克隆了转录激活所需的两个基因，并更详细地表征了它们的发育功能。我们鉴定为同源基因的转录激活因子Kismet基因的基因之一，编码大型核蛋白质家族。在胚泡阶段，母体编码的Kismet蛋白无处不在，需要正确分割胚胎。胃结合后，合子编码的Kismet蛋白在大脑和中枢神经系统中积累到最高水平。 Kismet蛋白的常见羧基末端结构域约为200公斤。在该公共区域内是一个41个氨基酸结构域，BRK结构域也存在于梵天蛋白中，这是染色质型复合物的亚基，也需要用于同源基因的转录激活。 Kismet蛋白之间的多样性是通过使用编码不同氨基末端扩展的替代外显子来产生的。在胚胎发生过程中，已经确定了两种主要的Kismet蛋白。较小的类蛋白的大小约为230公斤，而较大的类尺寸大于500公斤。除了在Kismet和梵天之间保守的BRK结构域外，较大的Kismet蛋白还具有在梵天蛋白中保守的另一个结构域，这是在染色质复制因子的几个亚基中发现的DNA刺激的ATPase结构蛋白。与Kismet相关的最密切相关的蛋白是CHD家族蛋白，除DNA刺激的ATPase域外，它们具有两个染色体（在较大的Kismet蛋白中）。去年，我们表明，果蝇中的另一种CHD家族蛋白DMI-2参与沉默的同源基因。我们还继续对OSA基因进行表征，这也是果蝇中同源基因转录激活所必需的。 OSA编码与酵母SWI1蛋白质同源的大核蛋白。酵母SWI1蛋白是染色质复合物复合物的一部分，其中包括我们以前研究过的另外两种蛋白质的同源物，即果蝇梵天和moira蛋白。我们已经表明，抗势基因的替代启动子之一需要高水平的OSA，梵天和Moira蛋白，并且这三个基因中的突变表现出强烈的遗传相互作用。此外，我们在其他几个基因中具有与这些蛋白质相互作用的分离突变，从而调节该抗抗病启动子的转录。我们目前正在克隆这些遗传筛选中鉴定的两个新基因。 - 果蝇，同源，转录，梵天，Kismet，OSA，Moira