Distinct functions of condensin I and II in mitotic chromosome assembly.

Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria.
Journal of Cell Science (Impact Factor: 5.33). 01/2005; 117(Pt 26):6435-45. DOI: 10.1242/jcs.01604
Source: PubMed

ABSTRACT Condensin is a protein complex associated with mitotic chromosomes that has been implicated in chromosome condensation. In vertebrates, two types of condensin complexes have recently been identified, called condensin I and II. Here, we show that in mammalian cells condensin II associates with chromatin in prophase, in contrast to condensin I which is cytoplasmic and can thus interact with chromosomes only after nuclear envelope breakdown. RNA interference experiments in conjunction with imaging of live and fixed cells revealed that condensin II is required for chromosome condensation in early prophase, whereas condensin I appears to be dispensable at this stage. By contrast, condensin I is required for the complete dissociation of cohesin from chromosome arms, for chromosome shortening and for normal timing of progression through prometaphase and metaphase, whereas normal condensin II levels are dispensable for these processes. After depletion of both condensin complexes, the onset of chromosome condensation is delayed until the end of prophase, but is then initiated rapidly before nuclear envelope breakdown. These results reveal that condensin II and I associate with chromosomes sequentially and have distinct functions in mitotic chromosome assembly.

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    ABSTRACT: Chromosome condensation during cell division is one of the most dramatic events in the cell cycle. Condensin and topoisomerase II are the most studied factors in chromosome condensation. However, their inactivation leads to only mild defects and little is known about roles of other factors. Here we took advantage of Drosophila oocytes to elucidate the roles of potential condensation factors by RNAi. Consistent with previous studies, depletion of condensin I subunits or topoisomerase II in oocytes only mildly affected chromosome condensation. In contrast, we found severe undercondensation of chromosomes after depletion of the Mi-2 containing NuRD nucleosome remodelling complex or the protein kinase NHK-1. The further phenotypic analysis suggests that Mi-2 and NHK-1 are involved in different pathways in chromosome condensation. We show that the main role of NHK-1 in chromosome condensation is to phosphorylate BAF and suppress its activity in linking chromosomes to nuclear envelope proteins. We further showed that NHK-1 is important for chromosome condensation in mitosis as well as in oocytes.
    Development 12/2014; 142(4). DOI:10.1242/jcs.158477 · 6.27 Impact Factor
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    ABSTRACT: Previous studies have indicated that non-SMC condensin I complex, subunit D2 (NCAPD2), an important protein in chromosome condensation, gene polymorphisms are associated with Alzheimer's disease. But no study has shown the relationship between NCAPD2 polymorphisms and Parkinson's disease. Here, we conducted a case-control study to investigate the relationship between NCAPD2 polymorphisms and the risk of Parkinson's disease in a Han Chinese population. Two single nuclear polymorphisms (SNPs) of NCAPD2 (rs7311174 and rs2072374) showed significant p values (p = 0.046 and p = 0.043, respectively) in 265 patients and 267 controls. Further analysis showed an effect of age and gender on the relationship between the two SNPs and the risk for Parkinson's disease. The A allele of rs7311174 and the T allele of rs2072374 were protective in the male patients (p = 0.016 and p = 0.019, respectively). The frequencies of the T allele of rs7311174 and the C allele of rs2072374 were significantly associated with late-onset Parkinson's disease (p = 0.048 and p = 0.044, respectively). This research demonstrates a positive relationship between the NCAPD2 gene and the risk for Parkinson's disease in a Han Chinese population and provides a potential genetic marker for sporadic Parkinson's disease.
    Genome 08/2014; 57(5):1-5. DOI:10.1139/gen-2014-0032 · 1.56 Impact Factor


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