Tpr directly binds to Mad1 and Mad2 and is important for the Mad1–Mad2-mediated mitotic spindle checkpoint

Lee, Sang Hyun; Sterling, Harry J.; Burlingame, Alma L.; McCormick, Frank

doi:10.1101/gad.1677208

Cited by 138 publications

(174 citation statements)

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“…Cells were then permeabilized with 0.2% Triton-X 100 in PBS (PBS-T) for 3 min, and were blocked in 3% BSA in PBS-T for 30 min, followed by incubation with appropriate antibodies. 38,39 To detect kinetochore MTBP, H-40 antibody (Santa Cruz Biotechnology) was used. Z-sectioned images were obtained on a Zeiss Axioplan II deconvolution microscope (Carl Zeiss, Thornwood, NY, USA) and processed as described by Guenther et al 40 Flow cytometric analysis.…”

Section: Discussionmentioning

confidence: 99%

MTBP plays a crucial role in mitotic progression and chromosome segregation

et al. 2011

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Murine double minute 2 (MDM2) binding protein (MTBP) has been implicated in tumor cell proliferation, but the underlying mechanisms remain unclear. The results of MTBP expression analysis during cell cycle progression demonstrated that MTBP protein was rapidly degraded during mitosis. Immunofluorescence studies revealed that a portion of MTBP was localized at the kinetochores during prometaphase. MTBP overexpression delayed mitotic progression from nuclear envelope breakdown (NEB) to anaphase onset and induced abnormal chromosome segregation such as lagging chromosomes, chromosome bridges, and multipolar chromosome segregation. Conversely, MTBP downmodulation caused an abbreviated metaphase and insufficient mitotic arrest, resulting in abnormal chromosome segregation, aneuploidy, decreased cell proliferation, senescence, and cell death, similar to that of Mad2 (mitotic arrest-deficient 2) downmodulation. Furthermore, MTBP downmodulation inhibited the accumulation of Mad1 and Mad2, but not BubR1 (budding uninhibited by benzimidazoles related 1), on the kinetochores, whereas MTBP overexpression inhibited the release of Mad2 from the metaphase kinetochores. These results may imply that MTBP has an important role in recruiting and/or retaining the Mad1/Mad2 complex at the kinetochores during prometaphase, but its degradation is required for silencing the mitotic checkpoint. Together, this study indicates that MTBP has a crucial role in proper mitotic progression and faithful chromosome segregation, providing new insights into regulation of the mitotic checkpoint. Cell Death and Differentiation (2011) 18, 1208-1219; doi:10.1038/cdd.2010.189; published online 28 January 2011Murine double minute 2 (MDM2) binding protein (MTBP) was originally identified as a protein that interacts with the oncoprotein MDM2, a major negative regulator of the tumor suppressor p53. 1 Overexpression of MTBP was shown to suppress cell proliferation and colony formation of several human cancer cell lines independent of their p53 status. 1 Brady et al. 2 reported that overexpression of MTBP in MCF7 cells resulted in MDM2 stabilization and subsequent p53 degradation. However, our previous findings demonstrated that complete deletion of MTBP in mice resulted in an early embryonic lethal phenotype independent of p53. 3 Furthermore, MTBP heterozygous mice (MTBP þ /À ) were neither tumor prone nor did they show any obvious phenotypes. Nonetheless, Mtbp þ /À p53 þ /À mice showed an increased frequency of metastatic tumors compared with p53 þ /À mice, suggesting the possible involvement of MTBP in tumor progression. 3 Recently, Odvody et al. 4 reported that a reduced MTBP level delayed Myc-induced lymphomagenesis independent of Mdm2 and p53. Thus, a vast majority of the results support the p53-independent functions of MTBP and its involvement in cell proliferation and tumor progression.

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Section: Discussionmentioning

confidence: 99%

MTBP plays a crucial role in mitotic progression and chromosome segregation

et al. 2011

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“…Tpr phosphorylated at S2059 associates with chromatin during telophase Tpr and its orthologs have been shown to be crucial for the progression of mitosis across different species (Lee et al, 2008;Lince-Faria et al, 2009;Nakano et al, 2010;Niepel et al, 2005). Immunofluorescence analysis using antibodies against Tpr and Tpr-pS2059 showed that the distribution of S2059-phosphorylated Tpr was the same as that of the Tpr protein during interphase and all the way up to metaphase (Fig.…”

Section: Tpr Is Phosphorylated At Residues S2059 and S2094 In Vivomentioning

confidence: 96%

“…Mad1 and Mad2 proteins have been shown to regulate the mitotic spindle checkpoint by inhibiting the Cdc20-APC complex (Dobles et al, 2000;Fang et al, 1998;Li and Benezra, 1996;Li et al, 1997). Tpr has been shown to directly interact with Mad1 and Mad2 proteins through its amino-and carboxy-terminal regions, respectively (Lee et al, 2008). We have previously shown that phosphorylation of Tpr by ERK2 enhances its interaction with ERK2 (Vomastek et al, 2008).…”

Section: Tpr Is Phosphorylated At Residues S2059 and S2094 In Vivomentioning

confidence: 99%

“…However, in the recent past, Tpr has been shown to play crucial roles in modulating other diverse cellular functions. Tpr associates with Mad1, Mad2 and the members of the dynein complex during mitosis, and these interactions have been found to be crucial for mediating the proper segregation of chromosomes during anaphase (Lee et al, 2008;Lince-Faria et al, 2009;Nakano et al, 2010). Tpr has also been shown to be required for establishing heterochromatin exclusion zones (HEZs) (Krull et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Phosphorylation of nucleoporin Tpr governs its differential localization and is required for its mitotic function

Rajanala

Sarkar

Jhingan

et al. 2014

Journal of Cell Science

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A major constituent of the nuclear basket region of the nuclear pore complex (NPC), nucleoporin Tpr, plays roles in regulating multiple important processes. We have previously established that Tpr is phosphorylated in both a MAP-kinase-dependent and MAP-kinaseindependent manner, and that Tpr acts as both a substrate and as a scaffold for ERK2 (also known as MAPK1). Here, we report the identification of S2059 and S2094 as the major novel ERKindependent phosphorylation sites and T1677, S2020, S2023 and S2034 as additional ERK-independent phosphorylation sites found in the Tpr protein in vivo. Our results suggest that protein kinase A phosphorylates the S2094 residue and that the site is hyperphosphorylated during mitosis. Furthermore, we find that Tpr is phosphorylated at the S2059 residue by CDK1 and the phosphorylated form distinctly localizes with chromatin during telophase. Abrogation of S2059 phosphorylation abolishes the interaction of Tpr with Mad1, thus compromising the localization of both Mad1 and Mad2 proteins, resulting in cell cycle defects. The identification of novel phosphorylation sites on Tpr and the observations presented in this study allow better understanding of Tpr functions.

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“…In Drosophila, a widely conserved protein, Megator, has been recently implicated in anaphase chromosome movement [190], through a specific role in spindle elongation. Surprisingly, this protein and its human counterpart Tpr, were shown to be required for an efficient SAC response, and its depletion accelerated anaphase entry [190,191].…”

Section: The Spindle Matrixmentioning

confidence: 99%

The perpetual movements of anaphase

Maiato

Lince-Faria

2010

Cell. Mol. Life Sci.

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One of the most extraordinary events in the lifetime of a cell is the coordinated separation of sister chromatids during cell division. This is truly the essence of the entire mitotic process and the reason for the most profound morphological changes in cytoskeleton and nuclear organization that a cell may ever experience. It all occurs within a very short time window known as "anaphase", as if the cell had spent the rest of its existence getting ready for this moment in an ultimate act of survival. And there is a good reason for this: no space for mistakes. Problems in the distribution of chromosomes during cell division have been correlated with aneuploidy, a common feature observed in cancers and several birth defects, and the main cause of spontaneous abortion in humans. In this paper we critically review the mechanisms of anaphase chromosome motion that resisted the scrutiny of more than one hundred years of research as part of a tribute to the pioneering work of Miguel Mota.

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Tpr directly binds to Mad1 and Mad2 and is important for the Mad1–Mad2-mediated mitotic spindle checkpoint

Cited by 138 publications

References 24 publications

MTBP plays a crucial role in mitotic progression and chromosome segregation

MTBP plays a crucial role in mitotic progression and chromosome segregation

Phosphorylation of nucleoporin Tpr governs its differential localization and is required for its mitotic function

The perpetual movements of anaphase

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