Johansen K M, Johansen J, Jin Y, Walker D L, Wang D, Wang Y
Department of Zoology and Genetics, Iowa State University, Ames 50011, USA.
Crit Rev Eukaryot Gene Expr. 1999;9(3-4):267-77. doi: 10.1615/critreveukargeneexpr.v9.i3-4.110.
Nuclear architecture is remodeled during interphase in response to changes in gene activity as well as to changing structural and functional requirements during cell division. Using the monoclonal antibody mAb2A, we have identified two proteins that appear to play important roles in these processes: JIL-1 is a tandem serine-threonine kinase implicated in the regulation of chromatin structure, whereas Skeletor is a novel protein participating in structural nuclear remodeling during the cell cycle. Antibody staining and live imaging of JIL-1-GFP transgenic flies show that JIL-1 localizes to the gene-rich interband regions of larval polytene chromosomes and is upregulated almost twofold on the hypertranscribed male X chromosome compared with autosomes. We propose that JIL-1 may play a role in transcriptional control potentially by regulating chromatin structure. The other mAb2A antigen, Skeletor, is distributed in a nuclear meshwork pattern that can be observed in stereo pair images to reorganize during the cell cycle to form a spindle-like structure at prometaphase that is distinct from the microtubule spindle apparatus. Taking advantage of the powerful molecular and genetic approaches offered in Drosophila, the study of these two proteins promises to yield new insight into what defines nuclear architecture at the molecular level and how its remodeling is regulated.
在间期，核结构会根据基因活性的变化以及细胞分裂过程中结构和功能需求的改变而重塑。利用单克隆抗体mAb2A，我们鉴定出了两种似乎在这些过程中发挥重要作用的蛋白质：JIL-1是一种串联丝氨酸-苏氨酸激酶，与染色质结构的调控有关；而Skeletor是一种新型蛋白质，参与细胞周期中的细胞核结构重塑。对JIL-1-GFP转基因果蝇进行抗体染色和实时成像显示，JIL-1定位于幼虫多线染色体富含基因的间带区域，与常染色体相比，在高度转录的雄性X染色体上其表达上调近两倍。我们推测JIL-1可能通过调节染色质结构在转录控制中发挥作用。另一种mAb2A抗原Skeletor以核网状模式分布，在立体配对图像中可观察到其在细胞周期中重新组织，在有丝分裂前期形成一种不同于微管纺锤体装置的纺锤样结构。利用果蝇中强大的分子和遗传方法，对这两种蛋白质的研究有望在分子水平上对决定核结构的因素及其重塑如何受到调控产生新的见解。
