Kinetochore localized Mad2 and Cdc20 is itself insufficient for triggering the mitotic checkpoint when Mps1 is low in Drosophila melanogaster neuroblasts
| Autor: | Michael J. Taggart, Ashleigh Herriott, M Sweeney, Jun-Yong Huang, Michael Whitaker |
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| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: |
Heterozygote
Mad2 Cdc20 Proteins Cell Cycle Proteins Biology Protein Serine-Threonine Kinases spindle assembly checkpoint Neuroblast Report Mad2 Proteins Animals Drosophila Proteins Cdc20 Mps1 Kinetochores Molecular Biology Mitosis Anaphase Kinetochore fungi Cell Biology Cell biology Spindle checkpoint Drosophila melanogaster Mitotic exit M Phase Cell Cycle Checkpoints Developmental Biology |
| Zdroj: | Cell Cycle |
| ISSN: | 1551-4005 1538-4101 |
| Popis: | The relationships between the kinetochore and checkpoint control remain unresolved. Here, we report the characterization of the in vivo behavior of Cdc20 and Mad2 and the relevant spindle assembly checkpoint (SAC) functions in the neuroblasts of a Drosophila Mps1 weak allele (ald (B4-2) ). ald (B4-2) third instar larvae brain samples contain only around 16% endogenous Mps1 protein, and the SAC function is abolished. However, this does not lead to rapid anaphase onset and mitotic exit, in contrast to the loss of Mad2 alone in a mad2 (EY) mutant. The level of GFP-Cdc20 recruitment to the kinetochore is unaffected in ald (B4-2) neuroblasts, while the level of GFP-Mad2 is reduced to just about 20%. Cdc20 and Mad2 display only monophasic exponential kinetics at the kinetochores. The ald (B4-2) heterozygotes expressed approximately 65% of normal Mps1 protein levels, and this is enough to restore the SAC function. The kinetochore recruitment of GFP-Mad2 in response to SAC activation increases by around 80% in heterozygotes, compared with just about 20% in ald (B4-2) mutant. This suggests a correlation between Mps1 levels and Mad2 kinetochore localization and perhaps the existence of a threshold level at which Mps1 is fully functional. The failure to arrest the mitotic progression in ald (B4-2) neuroblasts in response to colchicine treatment suggests that when Mps1 levels are low, approximately 20% of normal GFP-Mad2, alongside normal levels of GFP-Cdc20 kinetochore recruitments, is insufficient for triggering SAC signal propagation. |
| Databáze: | OpenAIRE |
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