- 作者: Hsueh-Hsuan Lin; Hsin-Ling Hsu; Ning-Hsing Yeh
- 作者服務機構: 1 Inslitute of Microbiology and Immunology, School of Life Science, National Yang-Ming University, 155 Li-Nong Street Sec. 2, Taipei, 112, Taiwan ROC; ; 2 Division of Molecular and Genomic Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town, Miaoli County, 350, Taiwan ROC
- 中文摘要: --
- 英文摘要: NuMA is a nuclear matrix protein in interphase and distributes to the spindle poles during mitosis. While the essential function of NuMA for mitotic spindle assembly is well established, a structural role of NuMA in interphase nucleus has also been proposed. Several observations suggest that the apoptotic degradation of NuMA may relate to chromatin condensation and micronucleation. Here we demonstrate that four apoptotic cleavage sites are clustered at a junction between the globular tail and the central coiled-coil domains of NuMA. Cleavage of a caspase-6-sensitive site at D1705 produced the R-form, a major tail-less product of NuMA during apoptosis. The other two cleavage sites were defined at D1726 and D1747 that were catalyzed, respectively, by caspase-3 and an unknown aspartase. A NuMA deletion mutant missing the entire cleavage region of residues 1701-1828 resisted degradation and protected cells from nuclear disruption upon apoptotic attack. Under such conditions, cytochrome c was released from mitochondria, but the subsequent apoptotic events such as caspase-3 activation, poly(ADP-ribose) polymerase degradation, and DNA fragmentation were attenuated. Conversely, the tail-less NuMA alone, a mutant mimicking the R-form, induced chromatin condensation and activated the death machinery. It supports that intact NuMA is a structural element in maintaining nuclear integrity.
- 中文關鍵字: --
- 英文關鍵字: apoptosis, caspase, chromatin condensation, micronucleation, nuclear matrix, nucleus, NuMA