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Chromosome-induced microtubule assembly mediated by TPX2 is required for spindle formation in HeLa cells
Oliver J Gruss1, Malte Wittmann, Hideki Yokoyama
1EMBL, Meyerhofstrasse 1, 69 117 Heidelberg, Germany.
Abstract:
In Xenopus laevis egg extracts, TPX2 is required for the Ran-GTP-dependent assembly of microtubules around chromosomes. Here we show that interfering with the function of the human homologue of TPX2 in HeLa cells causes defects in microtubule organization during mitosis. Suppressing the expression of human TPX2 by RNA interference leads to the formation of two microtubule asters that do not interact and do not form a spindle. Our results suggest that in vivo, even in the presence of duplicated centrosomes, spindle formation requires the function of TPX2 to generate a stable bipolar spindle with overlapping antiparallel microtubule arrays. This indicates that chromosome-induced microtubule production is a general requirement for the formation of functional spindles in animal cells.
Insights
TPX2 is essential for forming a bipolar spindle during cell division. Without functional TPX2, cells fail to organize microtubules correctly, preventing proper spindle assembly even with duplicated centrosomes.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Microtubule organization is crucial for cell division.
- TPX2 (Targeting Protein for Xklp2) is known to be involved in microtubule assembly in Xenopus egg extracts.
- The role of human TPX2 in vivo during mitosis is not fully understood.
Purpose of the Study:
- To investigate the function of human TPX2 in microtubule organization during mitosis in HeLa cells.
- To determine if TPX2 is required for spindle formation in animal cells.
Main Methods:
- RNA interference (RNAi) was used to suppress human TPX2 expression in HeLa cells.
- Microtubule organization and spindle formation were analyzed in cells with reduced TPX2 levels.
Main Results:
- Suppression of human TPX2 led to defects in microtubule organization.
- Cells lacking functional TPX2 formed two separate microtubule asters that failed to interact.
- A bipolar spindle did not form in the absence of TPX2, even with duplicated centrosomes.
Conclusions:
- Human TPX2 is essential for the proper formation of a stable bipolar spindle during mitosis.
- Chromosome-induced microtubule production, facilitated by TPX2, is a general requirement for functional spindle assembly in animal cells.