Nuclear-Cytoplasmic Shuttling of Chibby Controls β-Catenin Signaling

Li, Feng-Qian; Mofunanya, Adaobi; Fischer, Victoria; Hall, Jason C.; Takemaru, Ken‐Ichi

doi:10.1091/mbc.e09-05-0437

Cited by 48 publications

(72 citation statements)

References 62 publications

(103 reference statements)

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“…Drapper, Chibby, Apc) and by promoting its degradation (e.g. Apc) (Ahmed et al, 1998;Gao et al, 2008;Li et al, 2008Li et al, , 2010. These proteins negatively regulate β-catenin nuclear distribution, while Smp positively regulates it, so it is unlikely that Smp promotes β-catenin nuclear localization through the interaction with these proteins.…”

Section: Discussionmentioning

confidence: 99%

Simplet/Fam53b is required for Wnt signal transduction by regulating β-catenin nuclear localization

et al. 2014

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Canonical β-catenin-dependent Wnt signal transduction is important for several biological phenomena, such as cell fate determination, cell proliferation, stem cell maintenance and anterior-posterior axis formation. The hallmark of canonical Wnt signaling is the translocation of β-catenin into the nucleus where it activates gene transcription. However, the mechanisms regulating β-catenin nuclear localization are poorly understood. We show that Simplet/ Fam53B (Smp) is required for Wnt signaling by positively regulating β-catenin nuclear localization. In the zebrafish embryo, the loss of smp blocks the activity of two β-catenin-dependent reporters and the expression of Wnt target genes, and prevents nuclear accumulation of β-catenin. Conversely, overexpression of smp increases β-catenin nuclear localization and transcriptional activity in vitro and in vivo. Expression of mutant Smp proteins lacking either the nuclear localization signal or the β-catenin interaction domain reveal that the translocation of Smp into the nucleus is essential for β-catenin nuclear localization and Wnt signaling in vivo. We also provide evidence that mammalian Smp is involved in regulating β-catenin nuclear localization: the protein colocalizes with β-catenin-dependent gene expression in mouse intestinal crypts; siRNA knockdown of Smp reduces β-catenin nuclear localization and transcriptional activity; human SMP mediates β-catenin transcriptional activity in a dose-dependent manner; and the human SMP protein interacts with human β-catenin primarily in the nucleus. Thus, our findings identify the evolutionary conserved SMP protein as a regulator of β-catenindependent Wnt signal transduction.

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Section: Discussionmentioning

confidence: 99%

Simplet/Fam53b is required for Wnt signal transduction by regulating β-catenin nuclear localization

et al. 2014

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“…MBP-and His-tagged recombinant proteins were expressed in Escherichia coli strains BL21 and BL21(DE3) and purified by using amylose beads (New England BioLabs) and Ni-nitrilotriacetic acid (Ni-NTA) His-Bind resin (Novagen), respectively, according to the manufacturers' instructions. MBP pulldown assays were performed as previously described (33,34).…”

Section: Methodsmentioning

confidence: 99%

“…Coimmunoprecipitation (co-IP) assays and immunoblotting were performed as described previously (28,33). Briefly, for co-IP assays, transfected HEK293T cells were harvested in ice-cold lysis buffer (20 mM Tris-HCl [pH 8.0], 135 mM NaCl, 1.5 mM MgCl 2 , 1 mM EGTA, 1% Triton X-100, and 10% glycerol) with a protease inhibitor cocktail (Sigma) and incubated for 20 min on ice with intermit-tent agitation.…”

Section: Methodsmentioning

confidence: 99%

BAR Domain-Containing FAM92 Proteins Interact with Chibby1 To Facilitate Ciliogenesis

Chen

Fisher

et al. 2016

Molecular and Cellular Biology

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dChibby1 (Cby1) is a small, conserved coiled-coil protein that localizes to centrioles/basal bodies and plays a crucial role in the formation and function of cilia. During early stages of ciliogenesis, Cby1 is required for the efficient recruitment of small vesicles at the distal end of centrioles to facilitate basal body docking to the plasma membrane. Here, we identified family with sequence similarity 92, member A (FAM92A) and FAM92B, which harbor predicted lipid-binding BAR domains, as novel Cby1-interacting partners using tandem affinity purification and mass spectrometry. We found that in cultured cell lines, FAM92A colocalizes with Cby1 at the centrioles/basal bodies of primary cilia, while FAM92B is undetectable. In airway multiciliated cells, both FAM92A and -92B colocalize with Cby1 at the base of cilia. Notably, the centriolar localization of FAM92A and -92B depends largely on Cby1. Knockdown of FAM92A in RPE1 cells impairs ciliogenesis. Consistent with the membrane-remodeling properties of BAR domains, FAM92A and -92B in cooperation with Cby1 induce deformed membrane-like structures containing the small GTPase Rab8 in cultured cells. Our results therefore suggest that FAM92 proteins interact with Cby1 to promote ciliogenesis via regulation of membrane-remodeling processes.

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“…Western blotting was performed as described previously. 14,17 The primary antibodies used were as follows: rabbit anti-Cby1 13 ; mouse anti-GAPDH (Meridian Life Sciences); mouse anti-E-cadherin (BD Transduction Laboratories); mouse anti-ZO-1 (BD Transduction Laboratories); mouse anti-vimentin (Neomarkers); mouse anti-Flag M2 (Sigma); mouse anti-HA (Proteintech). All HRP-conjugated secondary antibodies were purchased from Jackson ImmunoResearch Laboratories.…”

Section: Co-immunoprecipitation and Western Blot Analysismentioning

confidence: 99%

“…16 We showed that Cby1 contains functional nuclear localization signal (NLS) and nuclear export signal (NES) motifs and constitutively shuttles between the nucleus and cytoplasm. 17 Direct interactions of 14-3-3 proteins with Cby1 facilitate Cby1 binding to CRM1 export receptor, while suppressing Cby1 binding to the nuclear import receptor importin-1a. This results in re-distribution of Cby1 and b-catenin into the cytoplasm, leading to repression of b-catenin target genes.…”

Section: Introductionmentioning

confidence: 99%

Chibby1 knockdown promotes mesenchymal-to-epithelial transition-like changes

Fischer

Wong

et al. 2017

Cell Cycle

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Chibby1 (Cby1) was originally isolated as a binding partner for b-catenin, a dual function protein in cell-cell adhesion and in canonical Wnt signaling. The canonical Wnt/b-catenin pathway is dysregulated in various diseases including cancer, most notably of the gastrointestinal origin. To investigate the role of Cby1 in colorectal tumorigenesis, we generated stable Cby1-knockdown (K D ) SW480 colon cancer cells. Unexpectedly, we found that Cby1 K D induces mesenchymal-to-epithelial transition (MET)-like changes in SW480 as well as in HEK293 cells. Cby1-K D cells displayed a cuboidal epithelial morphology with tight cellcell contacts. In Cby1-K D cells, the plasma membrane localization of E-cadherin and b-catenin was dramatically increased with formation of cortical actin rings, while the levels of the mesenchymal marker vimentin were decreased. Consistent with these changes, in wound healing assays, Cby1-K D cells exhibited epithelial cell-like properties as they migrated collectively as epithelial sheets. Furthermore, the anchorage-independent growth of Cby1-K D cells was reduced as determined by soft agar assays. These findings suggest that chronic Cby1 K D in colon cancer cells may counteract tumor progression by promoting the MET process.

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Nuclear-Cytoplasmic Shuttling of Chibby Controls β-Catenin Signaling

Cited by 48 publications

References 62 publications

Simplet/Fam53b is required for Wnt signal transduction by regulating β-catenin nuclear localization

Simplet/Fam53b is required for Wnt signal transduction by regulating β-catenin nuclear localization

BAR Domain-Containing FAM92 Proteins Interact with Chibby1 To Facilitate Ciliogenesis

Chibby1 knockdown promotes mesenchymal-to-epithelial transition-like changes

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