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Ataxin-1 regulates epithelial – mesenchymal transition of cervical cancer cells

View Article: PubMed Central - PubMed

ABSTRACT

The mutant form of the protein ataxin-1 (ATXN1) causes the neurodegenerative disease spinocerebellar ataxia type-1. Recently, ATXN1 was reported to enhance E-cadherin expression in the breast cancer cell line MCF-7, suggesting a potential association between ATXN1 and cancer development. In the present study, we discovered a novel mechanism through which ATXN1 regulates the epithelial–mesenchymal transition (EMT) of cancer cells. Hypoxia-induced upregulation of the Notch intracellular domain expression decreased ATXN1 expression via MDM2-associated ubiquitination and degradation. In cervical cancer cells, ATXN1 knockdown induced EMT by directly regulating Snail expression, leading to matrix metalloproteinase activation and the promotion of cell migration and invasion. These findings provide insights into a novel mechanism of tumorigenesis and will facilitate the development of new and more effective therapies for cancer.

No MeSH data available.


Related in: MedlinePlus

MDM2 promotes ubiquitination and degradation of ATXN1A. Left panel: HEK293 cells were co-transfected with HA-ATXN1 and Flag-MDM2. After transfection, cell lysates were immunoprecipitated with an anti-Flag antibody and subjected to western blotting. Right panel: HEK293 cells co-transfected with Myc-NICD and Flag-MDM2 were lysed, and the lysates were immunoprecipitated with an anti-Flag antibody and subjected to western blotting analysis. B. Western blotting analysis of HEK293 cells co-transfected with HA-ATXN1 and Flag-MDM2. C. Western blotting analysis of SiHa cells transfected with Myc-NICD in the presence or absence of MDM2 siRNA to determine the expression of Myc-NICD and MDM2. ATXN1 expression was normalized to β-actin levels. Numbers indicate the intensity ratio relative to the control lane (1.0). D. HEK293 cells were co-transfected with Myc-NICD, Flag-MDM2, and Xpress-ATXN1, with or without HA-Ub, and treated with MG132 for 6 h. ATXN1 was immunoprecipitated using an anti-Xpress antibody. Cell lysates were subjected to western blotting analysis with the indicated antibodies. HC represents the IgG heavy chain. IP (Immunoprecipitation), IB (Immunoblot), Xp (Xpress), HC (Heavy chain), Con (Control).
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Figure 3: MDM2 promotes ubiquitination and degradation of ATXN1A. Left panel: HEK293 cells were co-transfected with HA-ATXN1 and Flag-MDM2. After transfection, cell lysates were immunoprecipitated with an anti-Flag antibody and subjected to western blotting. Right panel: HEK293 cells co-transfected with Myc-NICD and Flag-MDM2 were lysed, and the lysates were immunoprecipitated with an anti-Flag antibody and subjected to western blotting analysis. B. Western blotting analysis of HEK293 cells co-transfected with HA-ATXN1 and Flag-MDM2. C. Western blotting analysis of SiHa cells transfected with Myc-NICD in the presence or absence of MDM2 siRNA to determine the expression of Myc-NICD and MDM2. ATXN1 expression was normalized to β-actin levels. Numbers indicate the intensity ratio relative to the control lane (1.0). D. HEK293 cells were co-transfected with Myc-NICD, Flag-MDM2, and Xpress-ATXN1, with or without HA-Ub, and treated with MG132 for 6 h. ATXN1 was immunoprecipitated using an anti-Xpress antibody. Cell lysates were subjected to western blotting analysis with the indicated antibodies. HC represents the IgG heavy chain. IP (Immunoprecipitation), IB (Immunoblot), Xp (Xpress), HC (Heavy chain), Con (Control).

Mentions: We next investigated whether ATXN1 and MDM2 interact. Therefore, we performed immunoprecipitation experiments in HEK293 cells and found that ATXN1 interacts with MDM2; furthermore, NICD also binds to MDM2 (Figure 3A). These results are consistent with a previous study in which NICD was found to bind to MDM2 [31]. Subsequent overexpression of HA-ATXN1 and Flag-MDM2 in HEK293 cells led to dramatic decreases in ATXN1 in the presence of MDM2 in a dose-dependent manner (Figure 3B). These data indicate that NICD induces the degradation of ATXN1 via MDM2-mediated ubiquitination.


Ataxin-1 regulates epithelial – mesenchymal transition of cervical cancer cells
MDM2 promotes ubiquitination and degradation of ATXN1A. Left panel: HEK293 cells were co-transfected with HA-ATXN1 and Flag-MDM2. After transfection, cell lysates were immunoprecipitated with an anti-Flag antibody and subjected to western blotting. Right panel: HEK293 cells co-transfected with Myc-NICD and Flag-MDM2 were lysed, and the lysates were immunoprecipitated with an anti-Flag antibody and subjected to western blotting analysis. B. Western blotting analysis of HEK293 cells co-transfected with HA-ATXN1 and Flag-MDM2. C. Western blotting analysis of SiHa cells transfected with Myc-NICD in the presence or absence of MDM2 siRNA to determine the expression of Myc-NICD and MDM2. ATXN1 expression was normalized to β-actin levels. Numbers indicate the intensity ratio relative to the control lane (1.0). D. HEK293 cells were co-transfected with Myc-NICD, Flag-MDM2, and Xpress-ATXN1, with or without HA-Ub, and treated with MG132 for 6 h. ATXN1 was immunoprecipitated using an anti-Xpress antibody. Cell lysates were subjected to western blotting analysis with the indicated antibodies. HC represents the IgG heavy chain. IP (Immunoprecipitation), IB (Immunoblot), Xp (Xpress), HC (Heavy chain), Con (Control).
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Related In: Results  -  Collection

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Figure 3: MDM2 promotes ubiquitination and degradation of ATXN1A. Left panel: HEK293 cells were co-transfected with HA-ATXN1 and Flag-MDM2. After transfection, cell lysates were immunoprecipitated with an anti-Flag antibody and subjected to western blotting. Right panel: HEK293 cells co-transfected with Myc-NICD and Flag-MDM2 were lysed, and the lysates were immunoprecipitated with an anti-Flag antibody and subjected to western blotting analysis. B. Western blotting analysis of HEK293 cells co-transfected with HA-ATXN1 and Flag-MDM2. C. Western blotting analysis of SiHa cells transfected with Myc-NICD in the presence or absence of MDM2 siRNA to determine the expression of Myc-NICD and MDM2. ATXN1 expression was normalized to β-actin levels. Numbers indicate the intensity ratio relative to the control lane (1.0). D. HEK293 cells were co-transfected with Myc-NICD, Flag-MDM2, and Xpress-ATXN1, with or without HA-Ub, and treated with MG132 for 6 h. ATXN1 was immunoprecipitated using an anti-Xpress antibody. Cell lysates were subjected to western blotting analysis with the indicated antibodies. HC represents the IgG heavy chain. IP (Immunoprecipitation), IB (Immunoblot), Xp (Xpress), HC (Heavy chain), Con (Control).
Mentions: We next investigated whether ATXN1 and MDM2 interact. Therefore, we performed immunoprecipitation experiments in HEK293 cells and found that ATXN1 interacts with MDM2; furthermore, NICD also binds to MDM2 (Figure 3A). These results are consistent with a previous study in which NICD was found to bind to MDM2 [31]. Subsequent overexpression of HA-ATXN1 and Flag-MDM2 in HEK293 cells led to dramatic decreases in ATXN1 in the presence of MDM2 in a dose-dependent manner (Figure 3B). These data indicate that NICD induces the degradation of ATXN1 via MDM2-mediated ubiquitination.

View Article: PubMed Central - PubMed

ABSTRACT

The mutant form of the protein ataxin-1 (ATXN1) causes the neurodegenerative disease spinocerebellar ataxia type-1. Recently, ATXN1 was reported to enhance E-cadherin expression in the breast cancer cell line MCF-7, suggesting a potential association between ATXN1 and cancer development. In the present study, we discovered a novel mechanism through which ATXN1 regulates the epithelial–mesenchymal transition (EMT) of cancer cells. Hypoxia-induced upregulation of the Notch intracellular domain expression decreased ATXN1 expression via MDM2-associated ubiquitination and degradation. In cervical cancer cells, ATXN1 knockdown induced EMT by directly regulating Snail expression, leading to matrix metalloproteinase activation and the promotion of cell migration and invasion. These findings provide insights into a novel mechanism of tumorigenesis and will facilitate the development of new and more effective therapies for cancer.

No MeSH data available.


Related in: MedlinePlus