Identificazione e caratterizzazione di geni che controllano il movimento dei cromosomi nella mitosi di Drosophila melanogaster
Author(s)
Pellacani, Claudia
Date Issued
February 20, 2009
Type
Doctoral Thesis
Abstract
Mitosis is the evolutionarily conserved process that enables a dividing cell to equally partition
its genetic material between the two daughter cells. The fidelity of mitotic division is crucial
for normal development of multicellular organisms and to prevent cancer or birth defects.
Understanding the molecular mechanisms of mitosis requires the identification of genes
involved in this process. Previous studies have shown that such genes can be readily
identified by RNA interference (RNAi) in Drosophila tissue culture cells. Exploiting the
powers of bioinformatics and RNAi technology, our laboratory has recently performed a large
screen aimed at detection of genes involved in the Drosophila mitotic process. This screen has
led to the identification of 155 mitotic genes, 70 of which have not been previously implicated
in cell division. Surprisingly, these studies showed that RNAi-mediated inactivation of
several highly conserved splicing factors results in strong defects in chromosome segregation.
My thesis project was focused on the functional characterization of two of these factors. They
are encoded by the CG6876 and CG10754 Drosophila genes, and are highly homologous
respectively to the PRPF31 and SF3A2 human genes. PRPF31 and SF3A2 are component of
two snRNPs involved in splicing regulation. To define the mitotic role of these splicing
factors I compared the phenotypes elicited by their depletion with that caused by RNAimediated
knockout of Ndc80/Hec1, which encodes a kinetochore protein that is thought to
interact with spindle microtubules. These analyses revealed that CG6876, CG10754 and
Ndc80/Hec1 have very similar mitotic roles. Both the splicing factors and the Ndc80/Hec1
protein are required for the formation of kinetochore-driven kinetochore fibers. In the absence
of these fibers spindle assembly is highly abnormal and the chromosomes fail to segregate.
Collectively, these results highlight an unanticipated role of splicing factors in spindle
assembly and chromosome segregation. Further studies will be required to determine the
precise role of these factors in kinetochore structure and function.
Additional information
Dottorato di ricerca in Genetica e biologia cellulare
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