SPINDLE ASSEMBLY · Keeping the spindle in shape: identification and characterization of new components involved for spindle formation
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2005-05-01 → 2006-04-30
- EU contribution
- €40,000
- Participants
- 1
- Scheme
- ERG
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Results in brief
Final Activity Report Summary - SPINDLE ASSEMBLY (Keeping the spindle in shape: identification and characterization of new components involved for spindle formation)
The bipolar spindle is a macromolecular machine used by the cell during mitosis to achieve proper chromosome segregation and division. Bipolarity is essential for proper distribution of the genetic material. In order to identify factors controlling bipolarity we used in vitro formed spindle-like structures in meiotic Xenopus egg extract after the addition of the small GTPase Ran. GTP-bound Ran appears to affect multiple aspects of microtubule behaviour, including the induction of bipolar spindle-like microtubule assemblies and we used this system to identify Ran effectors involved in spindle bi-orientation. We identified a complex that is required for the conversion of aster-like to spindle-like structures in Xenopus egg extract consisting of five proteins: two characterised MAPs (TPX2, XMAP215), a plus end-directed motor, Eg5, a mitotic kinase, Aurora A, and HURP, a protein associated with hepatocellular carcinoma. HURP protein was further characterized and found to be a new and essential component of the mitotic apparatus not only in vitro but also in mammalian cells. HURP is required in mammalian cells for proper spindle formation correct entry into anaphase and segregation of the chromosomes. HURP is the first MAP identified so far to affect microtubule stability and organisation in vitro by inducing a novel conformation of tubulin. HURP may exert its potential oncogenic action on hepatocellular carcinoma through its effect on tubulin conformation and stability.
Data: CORDIS, © European Union
Project objective
During each cell division a cell needs to distribute the genetic material equally to two daughter cells. To segregate chromosomes the cell uses a macromolecular machine: the bipolar spindle.A bipolar spindle forms also in vitro, in Xenopus M-phase egg extract, a system of extreme value to analyse the function of individual spindle components in a simplified context.Pioneered studies in egg extract led to the mechanistic insight of the role of the small GTPase Ran during mitosis. Ran-GTP was shown to regulate microtubule nucleation by releasing the inhibitory effect of import adaptors from factors like TPX2, in the proximity of the chromosomes.We have used the Xenopus extracts to identify additional Ran effectors involved in spindle bi-orientation. Amongst the proteins found, we identified a new protein, which during the course of our studies was reported to be over-expressed in human hepatocellular carcinoma (therefore called HURP).In this project we want to:- Characterise and analyse the molecular function and interplay of the newly identified component of the spindle both in vivo and in vitro.- Identify new proteins potentially involved in spindle assembly.- Discover potential relationship between deregulation of these proteins with specific types of cancer.For this purpose we will employ both the Xenopus egg system and mammalian cell lines, in order to combine the in vitro biochemical experiments with the temporal and spatial requirements observed in vivo. Moreover, analysis of biological samples from different types of cancer will indicate possible links of the proteins to oncogenesis.Given that mitotic defects and aneuploidy is a crucial hallmark associated with high malignancy and poor prognosis of cancer, the outcome of the studies outlined in this proposal may acquire primary importance to our understanding of how mitotic errors can lead to cell transformation.
Original text from CORDIS.
Participants
- DEPARTMENT OF MOLECULAR BIOLOGY AND GENETICS, DEMOCRITUS UNIVERSITY OF THRACE, GREECE · ALEXANDROUPOLISCoordinatorCity levelGreece
Links
Data: CORDIS, © European Union