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Filamin A phosphorylation by Akt promotes cell migration in response to arsenic.

Li L, Lu Y, Stemmer PM, Chen F - Oncotarget (2015)

Bottom Line: The results indicate that a cytoskeleton remodeling protein, filamin A, with a molecular weight around 280 kDa, is phosphorylated by Akt in HEK-293 cells treated with As(3+), which was also confirmed in human bronchial epithelial cell line, BEAS-2B cells.To further confirm the importance of Akt-dependent filamin A S2152 phosphorylation in As(3+)-induced cell migration, we over-expressed either wild type filamin A or the mutated filamin A in which the S2152 was substituted with alanine (S2152A).The capability of cell migration was reduced significantly in the cells expressing the mutated filamin A (S2152A).

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA.

ABSTRACT
We had previously reported that trivalent arsenic (As(3+)), a well-known environmental carcinogen, induces phosphorylation of several putative Akt substrates. In the present report, we characterized one of these substrates by immunoprecipitation and proteomics analysis. The results indicate that a cytoskeleton remodeling protein, filamin A, with a molecular weight around 280 kDa, is phosphorylated by Akt in HEK-293 cells treated with As(3+), which was also confirmed in human bronchial epithelial cell line, BEAS-2B cells. Additional biochemical and biological studies revealed that serine 2152 (S2152) of filamin A is phosphorylated by activated Akt in the cells treated with As(3+). To further confirm the importance of Akt-dependent filamin A S2152 phosphorylation in As(3+)-induced cell migration, we over-expressed either wild type filamin A or the mutated filamin A in which the S2152 was substituted with alanine (S2152A). The capability of cell migration was reduced significantly in the cells expressing the mutated filamin A (S2152A). Clinically, we found that increased expression of filamin A predicts poorer overall survival of the lung cancer patients with adenocarcinoma. Thus, these data suggest that Akt dependent filamin A phosphorylation is one of the key events in mediating As(3+)-induced carcinogenesis. Antagonizing Akt signaling can ameliorate As(3+)-induced filamin A phosphorylation and cell migration, which may serve as a molecular targeting strategy for malignancies associated with environmental As(3+) exposure.

No MeSH data available.


Related in: MedlinePlus

Silencing filamin A prevented As3+-induced cell migrationA. BEAS-2B cells were transfected with 50 nM control siRNA (siCtrl) or filamin A siRNA (siFlna) with or without treatment by 4 μM As3+ for 24 h. B. Representative images of the migration assays. BEAS-2B cells were treated as in (A). C. Semi-quantification of the migrated cells as shown in (B). Data are expressed as mean ± SD, n = 12, *p < 0.05.
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Figure 4: Silencing filamin A prevented As3+-induced cell migrationA. BEAS-2B cells were transfected with 50 nM control siRNA (siCtrl) or filamin A siRNA (siFlna) with or without treatment by 4 μM As3+ for 24 h. B. Representative images of the migration assays. BEAS-2B cells were treated as in (A). C. Semi-quantification of the migrated cells as shown in (B). Data are expressed as mean ± SD, n = 12, *p < 0.05.

Mentions: To answer whether filamin A phosphorylation served as a downstream signal for As3+-induced Akt activation that facilitates cell migration, we next silenced filamin A by transfection of the cells with filamin A specific siRNA (siFlna) followed by measuring the cell migration. Filamin A specific siRNA, siFlna, reduced the levels of both filamin A and the S2152-phosphorylated filamin A (pFilamin AS2152) notably (Fig. 4A). The control siRNA, siCtrl, exhibited no significant effects on these proteins, neither pFilamin A, nor total Filamin A. In cell migration assays, again, As3+ increased the number of migrated cells significantly (Figs. 4B and 4C). No inhibition of the As3+-induced cell migration was detected in the cells transfected with the control siRNA (siCtrl). In contrast, a strong inhibition of cell migration induced by As3+ was observed in the cells transfected with siFlna that specifically silences filamin A (Figs. 4B and 4C). These observations, thus, not only reinforced the notion that filamin A might be an important regulator for cell migration [24, 28], but also provided strong evidence indicating that filamin A is a downstream effecter to bridge As3+-induced Akt activation and migration.


Filamin A phosphorylation by Akt promotes cell migration in response to arsenic.

Li L, Lu Y, Stemmer PM, Chen F - Oncotarget (2015)

Silencing filamin A prevented As3+-induced cell migrationA. BEAS-2B cells were transfected with 50 nM control siRNA (siCtrl) or filamin A siRNA (siFlna) with or without treatment by 4 μM As3+ for 24 h. B. Representative images of the migration assays. BEAS-2B cells were treated as in (A). C. Semi-quantification of the migrated cells as shown in (B). Data are expressed as mean ± SD, n = 12, *p < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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Figure 4: Silencing filamin A prevented As3+-induced cell migrationA. BEAS-2B cells were transfected with 50 nM control siRNA (siCtrl) or filamin A siRNA (siFlna) with or without treatment by 4 μM As3+ for 24 h. B. Representative images of the migration assays. BEAS-2B cells were treated as in (A). C. Semi-quantification of the migrated cells as shown in (B). Data are expressed as mean ± SD, n = 12, *p < 0.05.
Mentions: To answer whether filamin A phosphorylation served as a downstream signal for As3+-induced Akt activation that facilitates cell migration, we next silenced filamin A by transfection of the cells with filamin A specific siRNA (siFlna) followed by measuring the cell migration. Filamin A specific siRNA, siFlna, reduced the levels of both filamin A and the S2152-phosphorylated filamin A (pFilamin AS2152) notably (Fig. 4A). The control siRNA, siCtrl, exhibited no significant effects on these proteins, neither pFilamin A, nor total Filamin A. In cell migration assays, again, As3+ increased the number of migrated cells significantly (Figs. 4B and 4C). No inhibition of the As3+-induced cell migration was detected in the cells transfected with the control siRNA (siCtrl). In contrast, a strong inhibition of cell migration induced by As3+ was observed in the cells transfected with siFlna that specifically silences filamin A (Figs. 4B and 4C). These observations, thus, not only reinforced the notion that filamin A might be an important regulator for cell migration [24, 28], but also provided strong evidence indicating that filamin A is a downstream effecter to bridge As3+-induced Akt activation and migration.

Bottom Line: The results indicate that a cytoskeleton remodeling protein, filamin A, with a molecular weight around 280 kDa, is phosphorylated by Akt in HEK-293 cells treated with As(3+), which was also confirmed in human bronchial epithelial cell line, BEAS-2B cells.To further confirm the importance of Akt-dependent filamin A S2152 phosphorylation in As(3+)-induced cell migration, we over-expressed either wild type filamin A or the mutated filamin A in which the S2152 was substituted with alanine (S2152A).The capability of cell migration was reduced significantly in the cells expressing the mutated filamin A (S2152A).

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA.

ABSTRACT
We had previously reported that trivalent arsenic (As(3+)), a well-known environmental carcinogen, induces phosphorylation of several putative Akt substrates. In the present report, we characterized one of these substrates by immunoprecipitation and proteomics analysis. The results indicate that a cytoskeleton remodeling protein, filamin A, with a molecular weight around 280 kDa, is phosphorylated by Akt in HEK-293 cells treated with As(3+), which was also confirmed in human bronchial epithelial cell line, BEAS-2B cells. Additional biochemical and biological studies revealed that serine 2152 (S2152) of filamin A is phosphorylated by activated Akt in the cells treated with As(3+). To further confirm the importance of Akt-dependent filamin A S2152 phosphorylation in As(3+)-induced cell migration, we over-expressed either wild type filamin A or the mutated filamin A in which the S2152 was substituted with alanine (S2152A). The capability of cell migration was reduced significantly in the cells expressing the mutated filamin A (S2152A). Clinically, we found that increased expression of filamin A predicts poorer overall survival of the lung cancer patients with adenocarcinoma. Thus, these data suggest that Akt dependent filamin A phosphorylation is one of the key events in mediating As(3+)-induced carcinogenesis. Antagonizing Akt signaling can ameliorate As(3+)-induced filamin A phosphorylation and cell migration, which may serve as a molecular targeting strategy for malignancies associated with environmental As(3+) exposure.

No MeSH data available.


Related in: MedlinePlus