Ding Yun, Yao Changfu, Lince-Faria Mariana, Rath Uttama, Cai Weili, Maiato Helder, Girton Jack, Johansen Kristen M, Johansen Jørgen
Department of Biochemistry, Biophysics, and Molecular Biology, 3156 Molecular Biology Building, Iowa State University, Ames, IA 50011, USA.
Dev Biol. 2009 Oct 1;334(1):253-63. doi: 10.1016/j.ydbio.2009.07.027. Epub 2009 Jul 24.
The chromodomain protein, Chromator, has been shown to have multiple functions that include regulation of chromatin structure as well as coordination of muscle remodeling during metamorphosis depending on the developmental context. In this study we show that mitotic neuroblasts from brain squash preparations from larvae heteroallelic for the two Chromator loss-of-function alleles Chro(71) and Chro(612) have severe microtubule spindle and chromosome segregation defects that were associated with a reduction in brain size. The microtubule spindles formed were incomplete, unfocused, and/or without clear spindle poles and at anaphase chromosomes were lagging and scattered. Time-lapse analysis of mitosis in S2 cells depleted of Chromator by RNAi treatment suggested that the lagging and scattered chromosome phenotypes were caused by incomplete alignment of chromosomes at the metaphase plate, possibly due to a defective spindle-assembly checkpoint, as well as of frayed and unstable microtubule spindles during anaphase. Expression of full-length Chromator transgenes under endogenous promoter control restored both microtubule spindle morphology as well as brain size strongly indicating that the observed mutant defects were directly attributable to lack of Chromator function.
色域蛋白Chromator已被证明具有多种功能，包括根据发育环境调节染色质结构以及在变态过程中协调肌肉重塑。在本研究中，我们发现，来自幼虫脑压片制备物的有丝分裂神经母细胞，对于两个功能丧失等位基因Chro(71)和Chro(612)是杂合等位基因，具有严重的微管纺锤体和染色体分离缺陷，这与脑尺寸减小有关。形成的微管纺锤体不完整、未聚焦和/或没有清晰的纺锤极，并且在后期染色体滞后和分散。通过RNAi处理耗尽Chromator的S2细胞中，有丝分裂的延时分析表明，滞后和分散的染色体表型是由染色体在中期板上未完全对齐引起的，这可能是由于纺锤体组装检查点缺陷，以及后期微管纺锤体磨损和不稳定所致。在内源启动子控制下全长Chromator转基因的表达恢复了微管纺锤体形态以及脑尺寸，强烈表明观察到的突变缺陷直接归因于Chromator功能的缺失。
