[Show abstract][Hide abstract] ABSTRACT: Hydrogen peroxide (H(2)O(2)) regulates the structure and function of 2-Cys peroxiredoxins (Prxs). Upon oxidation by excess H(2)O(2), Prxs become overoxidized to a sulfinic acid of its peroxidatic cysteine residue, resulting in a structural change from a small oligomer with peroxidase function to a large oligomer with chaperone function. Then, sulfiredoxin (Srx) reduces the overoxidized Prxs by an ATP-dependent mechanism. Although Srx is known to repair the overoxidized forms of Prx, the role of Srx in the reversal of Prx oligomerization remains to be elucidated. Here we investigated whether Srx1 directly facilitates the dissociation of yeast Prx1 (YPrx1) from a high-molecular-weight (HMW) complex to a low-molecular-weight (LMW) complex in vitro. Srx1 reactivates the YPrx1 peroxidase activity that is inactivated by H(2)O(2), whereas it decreases the chaperone activity enhanced by H(2)O(2). We show that Srx1 dissociates the H(2)O(2)-induced HMW YPrx1 complex, and that the Srx1 Cys84 residue is critical for its dissociation. In contrast to wild-type Srx1, an inactive Srx1 mutant (Srx1-C84S) did not induce the reactivation of inactivated YPrx1 or dissociation of the HMW YPrx1 complex. We revealed that Srx1 interacts directly with YPrx1 in yeast cells using bimolecular fluorescence complementation. Taken together, these findings suggest that Srx1 regulates YPrx1 function and structure in yeast cells through a direct interaction.
Full-text · Article · Feb 2013 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: Human peroxiredoxin 1 (hPrx1), a member of the peroxiredoxin family, detoxifies peroxide substrates and has been implicated in numerous biological processes, including cell growth, proliferation, differentiation, apoptosis, and redox signaling. To date, Prx1 has not been implicated in RNA metabolism. Here, we investigated the ability of hPrx1 to bind RNA and act as an RNA chaperone. In vitro, hPrx1 bound to RNA and DNA, and unwound nucleic acid duplexes. hPrx1 also acted as a transcription anti-terminator in an assay using an Escherichia coli strain containing a stem-loop structure upstream of the chloramphenicol resistance gene. The overall cellular level of hPrx1 expression was not increased at low temperatures, but the nuclear level of hPrx1 was increased. In addition, hPrx1 overexpression enhanced the survival of cells exposed to cold stress, whereas hPrx1 knockdown significantly reduced cell survival under the same conditions. These findings suggest that hPrx1 may perform biological functions as a RNA-binding protein, which are distinctive from known functions of hPrx1 as a reactive oxygen species scavenger.
Full-text · Article · Aug 2012 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: The epithelial-to-mesenchymal transition (EMT), which is induced by transforming growth factor-β1 (TGF-β1), is an important event that allows cancer cells to obtain invasive and metastatic characteristics. Although human peroxiredoxin 1 (hPrx1) has been implicated in tumor progression (e.g., invasion and metastasis), little is known about the role of hPrx1 in the EMT process during tumorigenesis. Here, we investigated the regulatory effect of hPrx1 during TGF-β1-induced EMT in A549 lung adenocarcinoma cells. We observed that high hPrx1 levels downregulated E-cadherin expression, and low hPrx1 levels upregulated E-cadherin expression, suggesting that the hPrx1 level may be correlated with EMT. Knockdown of hPrx1 significantly inhibited TGF-β1-induced EMT and cell migration, whereas hPrx1 overexpression enhanced TGF-β1-induced EMT and cell migration. In contrast to wild-type hPrx1, a peroxidase-inactive hPrx1 mutant (hPrx1-C51S) resulted in markedly increased E-cadherin expression. Moreover, hPrx1 regulated the expression of two E-cadherin transcriptional repressors, Snail and Slug. These findings provide new insight into the role of hPrx1 in regulating TGF-β1-induced EMT.
No preview · Article · Mar 2012 · Biochemical and Biophysical Research Communications