Adenomatous polyposis coli and EB1 localize in close proximity of the mother centriole and EB1 is a functional component of centrosomes

Louie, Ryan K.; Bahmanyar, Shirin; Siemers, Kathleen A.; Votin, Violet; Chang, Paul; Stearns, Tim; Nelson, W. James; Barth, Angela I.M.

doi:10.1242/jcs.00939

Cited by 139 publications

(159 citation statements)

References 47 publications

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“…It is conceivable that direct dephosphorylation via PP2A could play an important role. Some of the plus end-binding MAPs, such as EB1 and APC, have also been clearly localized to centrosomes [72,89,90], and ectopic expression of either induces microtubule bundling and nocodazole resistant microtubles. Interestingly, APC associates with PP2A B' subunits [91], though the importance of this association for its cytoskeletal functions is unknown.…”

Section: Discussionmentioning

confidence: 99%

“…Cyclin G2 immunosignals on the blot were maximal in the lanes containing the peak γ-tubulin signal (Fig 6A). Also, note the comparable distribution through the sucrose gradient of both the cyclin G2 and the peak γ-tubulin immunosignals with another known centrosome localized protein, adenomatous polyposis coli (APC) [72].…”

Section: Endogenous Cyclin G2 and Pp2a Co-purify With Isolated Centromentioning

confidence: 99%

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Cyclin G2 is a centrosome-associated nucleocytoplasmic shuttling protein that influences microtubule stability and induces a p53-dependent cell cycle arrest

Don

Dallapiazza

Bennin

et al. 2006

Experimental Cell Research

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Cyclin G2 is an atypical cyclin that associates with active protein phosphatase 2A. Cyclin G2 gene expression correlates with cell cycle inhibition; it is significantly upregulated in response to DNA damage and diverse growth inhibitory stimuli, but repressed by mitogenic signals. Ectopic expression of cyclin G2 promotes cell cycle arrest, cyclin dependent kinase 2 inhibition, and the formation of aberrant nuclei [1]. Here we report that endogenous cyclin G2 copurifies with centrosomes and microtubules (MT), and that ectopic G2 expression alters microtubule stability. We find exogenous and endogenous cyclin G2 present at microtubule organizing centers (MTOCs) where it colocalizes with centrosomal markers in a variety of cell lines. We previously reported that cyclin G2 forms complexes with active protein phosphatase 2A (PP2A) and colocalizes with PP2A in a detergent resistant compartment. We now show that cyclin G2 and PP2A colocalize at MTOCs in transfected cells, and that the endogenous proteins copurify with isolated centrosomes. Displacement of the endogenous centrosomal scaffolding protein AKAP450 that anchors PP2A at the centrosome, resulted in the depletion of centrosomal cyclin G2. We find that ectopic expression of cyclin G2 induces microtubule bundling and resistance to depolymerization, inhibition of polymer regrowth from MTOCs, and a p53 dependent cell cycle arrest. Furthermore, we determined that a 100 amino acid carboxy-terminal region of cyclin G2 is sufficient to both direct GFP localization to centrosomes and induce cell cycle inhibition. Colocalization of endogenous cyclin G2 with only one of two GFPcentrin tagged centrioles, the mature centriole present at microtubule foci, indicate that cyclin G2 resides primarily on the mother centriole. Copurification of cyclin G2 and PP2A subunits with microtubules and centrosomes, together with the effects of ectopic cyclin G2 on cell cycle progression, nuclear morphology, and microtubule growth and stability, suggests that cyclin G2 may modulate the cell cycle and cellular division processes through modulation of PP2A and centrosomal associated activities.

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Section: Discussionmentioning

confidence: 99%

Section: Endogenous Cyclin G2 and Pp2a Co-purify With Isolated Centromentioning

confidence: 99%

Cyclin G2 is a centrosome-associated nucleocytoplasmic shuttling protein that influences microtubule stability and induces a p53-dependent cell cycle arrest

Don

Dallapiazza

Bennin

et al. 2006

Experimental Cell Research

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“…The EB1 knockdown vector (pSilencer-EB1) and the control RNAi vector (pSilencer -control) were constructed as described previously . The EB1 RNAi was targeted against the human EB1 sequence: 5 0 -TTGCCTTGAAGAAAGTGAA-3 0 (Louie et al, 2004); while the control RNAi was targeted against the sequence: 5 0 -GACTCTTCCAGTGGTTTAA-3 0 , which is with limited homology to any known sequences in the human genome. The APC expression plasmid was a kind gift from Professor B Vogelstein (John Hopkins University, Baltimore, MD, USA).…”

Section: Plasmid Constructions Cell Culture and Transfectionmentioning

confidence: 99%

Overexpression of EB1 in human esophageal squamous cell carcinoma (ESCC) may promote cellular growth by activating β-catenin/TCF pathway

et al. 2005

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Esophageal squamous cell carcinoma (ESCC) has a multifactorial etiology involving environmental and/or genetic factors. End-binding protein 1 (EB1), which was cloned as an interacting partner of the adenomatous polyposis coli (APC) tumor suppressor protein, was previously found overexpressed in ESCC. However, the precise role of EB1 in the development of this malignancy has not yet been elucidated. In this study, we analysed freshly resected ESCC specimens and demonstrated that EB1 was overexpressed in approximately 63% of tumor samples compared to matched normal tissue. We report that overexpression of EB1 in the ESCC line EC9706 significantly promotes cell growth, whereas suppression of EB1 protein level by RNA interference significantly inhibited growth of esophageal tumor cells. In addition, EB1 overexpression induced nuclear accumulation of b-catenin and promoted the transcriptional activity of b-catenin/T-cell factor (TCF). These effects were partially or completely abolished by coexpression of APC or DN TCF4, respectively. Also, we found that EB1 affected the interaction between b-catenin and APC. Furthermore, EB1 overexpression was correlated with cytoplasmic/ nuclear accumulation of b-catenin in primary human ESCC. Taken together, these results support the novel hypothesis that EB1 overexpression may play a role in the development of ESCC by affecting APC function and activating the b-catenin/TCF pathway. Oncogene (2005) 24, 6637-6645.

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“…Paradoxically, EB1/Bim1 and APC/Kar9 can also localize to microtubule-organizing centers; centrosomes or spindle pole bodies (SPBs) in yeast, independently of astral microtubules (Liakopoulos et al, 2003;Louie et al, 2004;Maekawa and Schiebel, 2004). The asymmetric localization of Kar9 to the SPB destined to enter the bud ("old" SPB, or SPB b ) and to astral microtubules that emanate from the SPB b is critical for proper spindle placement and orientation (Liakopoulos et al, 2003;Maekawa et al, 2003;Maekawa and Schiebel, 2004;Moore et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

γ-Tubulin Is Required for Proper Recruitment and Assembly of Kar9–Bim1 Complexes in Budding Yeast

Cuschieri

Miller

Vogel

2006

MBoC

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Microtubule plus-end-interacting proteins (؉TIPs) promote the dynamic interactions between the plus ends (؉ends) of astral microtubules and cortical actin that are required for preanaphase spindle positioning. Paradoxically, ؉TIPs such as the EB1 orthologue Bim1 and Kar9 also associate with spindle pole bodies (SPBs), the centrosome equivalent in budding yeast. Here, we show that deletion of four C-terminal residues of the budding yeast ␥-tubulin Tub4 (tub4-⌬dsyl) perturbs Bim1 and Kar9 localization to SPBs and Kar9-dependant spindle positioning. Surprisingly, we find Kar9 localizes to microtubule ؉ends in tub4-⌬dsyl cells, but these microtubules fail to position the spindle when targeted to the bud. Using cofluorescence and coaffinity purification, we show Kar9 complexes in tub4-⌬dsyl cells contain reduced levels of Bim1. Astral microtubule dynamics is suppressed in tub4-⌬dsyl cells, but it are restored by deletion of Kar9. Moreover, Myo2-and F-actin-dependent dwelling of Kar9 in the bud is observed in tub4-⌬dsyl cells, suggesting defective Kar9 complexes tether microtubule ؉ends to the cortex. Overproduction of Bim1, but not Kar9, restores Kar9-dependent spindle positioning in the tub4-⌬dsyl mutant, reduces cortical dwelling, and promotes Bim1-Kar9 interactions. We propose that SPBs, via the tail of Tub4, promote the assembly of functional ؉TIP complexes before their deployment to microtubule ؉ends.

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Adenomatous polyposis coli and EB1 localize in close proximity of the mother centriole and EB1 is a functional component of centrosomes

Cited by 139 publications

References 47 publications

Cyclin G2 is a centrosome-associated nucleocytoplasmic shuttling protein that influences microtubule stability and induces a p53-dependent cell cycle arrest

Cyclin G2 is a centrosome-associated nucleocytoplasmic shuttling protein that influences microtubule stability and induces a p53-dependent cell cycle arrest

Overexpression of EB1 in human esophageal squamous cell carcinoma (ESCC) may promote cellular growth by activating β-catenin/TCF pathway

γ-Tubulin Is Required for Proper Recruitment and Assembly of Kar9–Bim1 Complexes in Budding Yeast

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