Nelson Christian R, Hwang Tom, Chen Pin-Hsi, Bhalla Needhi
Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064.
Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
J Cell Biol. 2015 Nov 9;211(3):503-16. doi: 10.1083/jcb.201505114. Epub 2015 Nov 2.
The spindle checkpoint acts during cell division to prevent aneuploidy, a hallmark of cancer. During checkpoint activation, Mad1 recruits Mad2 to kinetochores to generate a signal that delays anaphase onset. Yet, whether additional factors contribute to Mad2's kinetochore localization remains unclear. Here, we report that the conserved AAA+ ATPase TRIP13(PCH-2) localizes to unattached kinetochores and is required for spindle checkpoint activation in Caenorhabditis elegans. pch-2 mutants effectively localized Mad1 to unattached kinetochores, but Mad2 recruitment was significantly reduced. Furthermore, we show that the C. elegans orthologue of the Mad2 inhibitor p31(comet)(CMT-1) interacts with TRIP13(PCH-2) and is required for its localization to unattached kinetochores. These factors also genetically interact, as loss of p31(comet)(CMT-1) partially suppressed the requirement for TRIP13(PCH-2) in Mad2 localization and spindle checkpoint signaling. These data support a model in which the ability of TRIP13(PCH-2) to disassemble a p31(comet)/Mad2 complex, which has been well characterized in the context of checkpoint silencing, is also critical for spindle checkpoint activation.
纺锤体检查点在细胞分裂过程中发挥作用，以防止非整倍体的出现，而非整倍体是癌症的一个标志。在检查点激活过程中，Mad1将Mad2招募到动粒上，以产生一个延迟后期开始的信号。然而，是否有其他因素有助于Mad2在动粒上的定位仍不清楚。在这里，我们报告保守的AAA+ATP酶TRIP13（PCH-2）定位于未附着的动粒，并且是秀丽隐杆线虫纺锤体检查点激活所必需的。pch-2突变体有效地将Mad1定位于未附着的动粒，但Mad2的招募显著减少。此外，我们表明Mad2抑制剂p31（彗星）（CMT-1）的秀丽隐杆线虫直系同源物与TRIP13（PCH-2）相互作用，并且是其定位于未附着动粒所必需的。这些因子在遗传上也相互作用，因为p31（彗星）（CMT-1）的缺失部分抑制了Mad2定位和纺锤体检查点信号传导中对TRIP13（PCH-2）的需求。这些数据支持了一个模型，即TRIP13（PCH-2）拆解p31（彗星）/Mad2复合物的能力，这在检查点沉默的背景下已得到充分表征，对纺锤体检查点激活也至关重要。
