Rho-dependent control of anillin behavior during cytokinesis

Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA.
The Journal of Cell Biology (Impact Factor: 9.83). 02/2008; 180(2):285-94. DOI: 10.1083/jcb.200709005
Source: PubMed


Anillin is a conserved protein required for cytokinesis but its molecular function is unclear. Anillin accumulation at the cleavage furrow is Rho guanine nucleotide exchange factor (GEF)(Pbl)-dependent but may also be mediated by known anillin interactions with F-actin and myosin II, which are under RhoGEF(Pbl)-dependent control themselves. Microscopy of Drosophila melanogaster S2 cells reveal here that although myosin II and F-actin do contribute, equatorial anillin localization persists in their absence. Using latrunculin A, the inhibitor of F-actin assembly, we uncovered a separate RhoGEF(Pbl)-dependent pathway that, at the normal time of furrowing, allows stable filamentous structures containing anillin, Rho1, and septins to form directly at the equatorial plasma membrane. These structures associate with microtubule (MT) ends and can still form after MT depolymerization, although they are delocalized under such conditions. Thus, a novel RhoGEF(Pbl)-dependent input promotes the simultaneous association of anillin with the plasma membrane, septins, and MTs, independently of F-actin. We propose that such interactions occur dynamically and transiently to promote furrow stability.

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    • "Interestingly, the 3 proteins that comprise this panel model are associated with distinct pathways in cancer biology. ANLN, initially characterised as a human homologue of anillin, a Drosophila actin-binding protein, is essential for the organisation of actin cables in the cleavage furrow, and plays a key role in cytokinesis and cell cycle progression [56-59]. ANLN has been demonstrated as a marker of poor prognosis, relating to aggressive cancer phenotypes [60]. "
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    ABSTRACT: Background Although omic-based discovery approaches can provide powerful tools for biomarker identification, several reservations have been raised regarding the clinical applicability of gene expression studies, such as their prohibitive cost. However, the limited availability of antibodies is a key barrier to the development of a lower cost alternative, namely a discrete collection of immunohistochemistry (IHC)-based biomarkers. The aim of this study was to use a systematic approach to generate and screen affinity-purified, mono-specific antibodies targeting progression-related biomarkers, with a view towards developing a clinically applicable IHC-based prognostic biomarker panel for breast cancer. Methods We examined both in-house and publicly available breast cancer DNA microarray datasets relating to invasion and metastasis, thus identifying a cohort of candidate progression-associated biomarkers. Of these, 18 antibodies were released for extended analysis. Validated antibodies were screened against a tissue microarray (TMA) constructed from a cohort of consecutive breast cancer cases (n = 512) to test the immunohistochemical surrogate signature. Results Antibody screening revealed 3 candidate prognostic markers: the cell cycle regulator, Anillin (ANLN); the mitogen-activated protein kinase, PDZ-Binding Kinase (PBK); and the estrogen response gene, PDZ-Domain Containing 1 (PDZK1). Increased expression of ANLN and PBK was associated with poor prognosis, whilst increased expression of PDZK1 was associated with good prognosis. A 3-marker signature comprised of high PBK, high ANLN and low PDZK1 expression was associated with decreased recurrence-free survival (p < 0.001) and breast cancer-specific survival (BCSS) (p < 0.001). This novel signature was associated with high tumour grade (p < 0.001), positive nodal status (p = 0.029), ER-negativity (p = 0.006), Her2-positivity (p = 0.036) and high Ki67 status (p < 0.001). However, multivariate Cox regression demonstrated that the signature was not a significant predictor of BCSS (HR = 6.38; 95% CI = 0.79-51.26, p = 0.082). Conclusions We have developed a comprehensive biomarker pathway that extends from discovery through to validation on a TMA platform. This proof-of-concept study has resulted in the identification of a novel 3-protein prognostic panel. Additional biochemical markers, interrogated using this high-throughput platform, may further augment the prognostic accuracy of this panel to a point that may allow implementation into routine clinical practice.
    BMC Cancer 04/2013; 13(1):175. DOI:10.1186/1471-2407-13-175 · 3.36 Impact Factor
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    • "Our data supports an interaction between Ect2 and anillin at the cortex. In human and Drosophila cells, anillin depletion causes lateral instability of the contractile ring and loss of TCA-fixed RhoA suggesting it stabilizes the division plane and feeds back to upstream pathways [28], [29], [30], [31], [32]. In Drosophila, anillin interacts with RacGAP50C (Cyk-4 homologue) [33], [34], possibly to crosslink the central spindle with the cortex and we hypothesize that the anillin-Ect2 interaction may have a similar function in human cells. "
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    ABSTRACT: Cytokinesis occurs due to the RhoA-dependent ingression of an actomyosin ring. During anaphase, the Rho GEF (guanine nucleotide exchange factor) Ect2 is recruited to the central spindle via its interaction with MgcRacGAP/Cyk-4, and activates RhoA in the central plane of the cell. Ect2 also localizes to the cortex, where it has access to RhoA. The N-terminus of Ect2 binds to Cyk-4, and the C-terminus contains conserved DH (Dbl homologous) and PH (Pleckstrin Homology) domains with GEF activity. The PH domain is required for Ect2's cortical localization, but its molecular function is not known. In cultured human cells, we found that the PH domain interacts with anillin, a contractile ring protein that scaffolds actin and myosin and interacts with RhoA. The anillin-Ect2 interaction may require Ect2's association with lipids, since a novel mutation in the PH domain, which disrupts phospholipid association, weakens their interaction. An anillin-RacGAP50C (homologue of Cyk-4) complex was previously described in Drosophila, which may crosslink the central spindle to the cortex to stabilize the position of the contractile ring. Our data supports an analogous function for the anillin-Ect2 complex in human cells and one hypothesis is that this complex has functionally replaced the Drosophila anillin-RacGAP50C complex. Complexes between central spindle proteins and cortical proteins could regulate the position of the contractile ring by stabilizing microtubule-cortical interactions at the division plane to ensure the generation of active RhoA in a discrete zone.
    PLoS ONE 04/2012; 7(4):e34888. DOI:10.1371/journal.pone.0034888 · 3.23 Impact Factor
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    • "Although anillin has not been shown to bind phospholipids directly, the presence of a conserved pleckstrin homology domain (Oegema et al., 2000) suggests that anillin may also interact with membranes. Indeed, in septin knockdown cells, anillin localizes to the membrane in a Rho-dependent manner (Straight et al., 2005; Hickson and O&apos;Farrell, 2008; Piekny and Glotzer, 2008). Anillin binds and bundles actin filaments and also binds myosin II, thereby interacting directly with both major components of the contractile ring (Field and Alberts, 1995; Straight et al., 2005). "
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    ABSTRACT: The scaffolding protein anillin is required for completion of cytokinesis. Anillin binds filamentous (F) actin, nonmuscle myosin II, and septins and in cell culture models has been shown to restrict actomyosin contractility to the cleavage furrow. Whether anillin also serves this function during the incomplete cytokinesis that occurs in developing germ cells has remained unclear. Here, we show that anillin is required for cytokinesis in dividing Drosophila melanogaster spermatocytes and that anillin, septins, and myosin II stably associate with the cleavage furrow in wild-type cells. Anillin is necessary for recruitment of septins to the cleavage furrow and for maintenance of F-actin and myosin II at the equator in late stages of cytokinesis. Remarkably, expression of DE-cadherin suppresses the cytokinesis defect of anillin-depleted spermatocytes. DE-cadherin recruits beta-catenin (armadillo) and alpha-catenin to the cleavage furrow and stabilizes F-actin at the equator. Similarly, E-cadherin expression suppresses the cytokinesis defect caused by anillin knockdown in mouse L-fibroblast cells. Our results show that the anillin-septin and cadherin-catenin complexes can serve as alternative cassettes to promote tight physical coupling of F-actin and myosin II to the cleavage furrow and successful completion of cytokinesis.
    Molecular biology of the cell 03/2010; 21(9):1482-93. DOI:10.1091/mbc.E09-08-0714 · 4.47 Impact Factor
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