Oxidized S100A4 inhibits the activation of protein phosphatase 5 through S100A1 in MKN-45 gastric carcinoma cells

Abstract

Abstract. S100 proteins bind to numerous target proteins, as well as other S100 proteins and activate signaling cascades. S100 proteins can be modified by various post-translational modifications, such as phosphorylation, methylation and acetylation. In addition, oxidation is important for modulating their activities. Previous studies have shown that S100A1 interacts with S100A4 in vitro and in vivo. Due to this potential cross-talk among the S100 proteins, the aim of the present study was to examine whether S100A4 modulates the activity of S100A1. S100A4 was readily oxidized and formed disulfide-linked dimers and oligomers. Although non-oxidized S100A4 bound to protein phosphatase 5 (PP5), the Cu-oxidized S100A4 failed to bind PP5. Instead, the Cu-oxidized S100A4 directly interacted with S100A1 and prevented PP5 activation. Hydrogen peroxide induced S100A4 oxidation in MKN-45 gastric adenocarcinoma cells and decreased S100A1-PP5 interaction, resulted in the inhibition of PP5 activation by S100A1. These data indicate that oxidized S100A4 regulates PP5 activity in a unique manner under oxidative stress conditions. Introduction S100A4 protein is a member of the EF-hand calcium ion-binding protein family, of which >25 members have been found in humans (1). They are 25-65% homologous at the amino acid level, while the sequence of the linker (hinge) region and the C-terminal extension are the most variable among the S100 proteins. Each S100 monomer contains two EF-hand Ca 2+ -binding sites. Ca 2+ -binding causes a conformational change and exposure of a hydrophobic surface allowing interaction with target proteins (2). They do not possess enzymatic activity, but rather regulate the activity of target proteins. Several proteins have been identified as S100A4 targets, including liprin β1 (3), methionine aminopeptidase (4), the p53 tumor suppressor protein (5) and the heavy chain of non-muscle myosin II (6). In addition, S100A4 is capable of forming heterodimers with S100A1 (7,8), which is likely to increase its functional potential. Previous studies have shown that S100A4 interacts with S100A1 via heterodimer formation and that S100A1 can antagonize function of S100A4 (9,10). It has been a general observation that two-hybrid screenings utilizing S100 proteins have primarily detected other S100 family members as targets (11)(12)(13).We have previously demonstrated that S100A1, A2, A6 and S100B interact with the tetratricopeptide repeat (TPR) domain of PP5 in a Ca 2+ -dependent manner and significantly activate its phosphatase activity (14). PP5 is a member of the phosphoprotein phosphatase (PPP) family of a serine/threonine phosphatase (15). PP5 contains a C-terminal catalytic domain and N-terminal three TPR motifs that are unique in the PPP family (16,17). The TPR motif consists of 34 amino acid sequences, and between 3 and 16 copies of the motif are arranged in the proteins as tandem arrays (18,19). This motif can act as an interaction scaffold for protein complex formation. PP5 is a negative regulator of the apoptosi...

Interaction of S100A1 with LATS1 promotes cell growth through regulation of the Hippo pathway in hepatocellular carcinoma

“…The overexpression of S100A4 decreases the sensitivity of HT29 colon cancer human cells to methotrexate, whereas its knockdown causes chemosensitization towards methotrexate ( 27 ). Considering the interaction of S100A1 with S100A4 and their regulatory association ( 13 , 14 , 28 , 29 ), it is likely that S100A1 sensitizes HCC cells to DDP through S100A4.…”

Competing Roles of Ca2+ and Nonmuscle Myosin IIA on the Dynamics of the Metastasis-Associated Protein S100A4

“…46,47 Moreover, cysteine residues at the dimer surface of S100A4 in the extracellular space may form disulfide bonds when they are oxidized. 48,49 Despite the wealth of structural information, our knowledge on the dynamics is quite limited. Insights into the molecular dynamics (MD) of S100A4 and the mechanisms controlling the (dis)assembly of NMIIA may contribute to the design of new inhibitors to disrupt the interaction of S100A4 with NMIIA to prevent the spread of tumor cells.…”

“…Furthermore, an experimental study found that mutation of the C-terminal EF-hand of S100A4 reduces Ca 2+ binding and cell motility/invasion in vitro and the affinity of the interaction of S100A4 and NMIIA isoform, and metastasis promotion . Another study showed that the C-terminal lysine (residue 101) in wild-type S100A4 increases the rate of association between S100A4 and NMIIA isoform, suggesting that the C-terminal region of S100A4 is an important inhibitor-binding site for its metastasis-inducing properties. , Moreover, cysteine residues at the dimer surface of S100A4 in the extracellular space may form disulfide bonds when they are oxidized. , …”

S100A4 in cancer progression and metastasis: A systematic review

“…Non-oxidized S100A4 is able to bind to protein phosphatase 5 (PP5), whereas the oxidized S100A4 protein disulfide-linked dimers and oligomers directly interacts with the S100A1 that cannot bind to PP5. S100A4 oxidation could be induced by hydrogen peroxide treatment in gastric cancer cells, decreasing S100A4-PP5 interaction and the inhibition of PP5 activation process, which is closely associated with gastric cancer cell malignant phenotypes [ 90 ]. S100A4 can also promote the cancer stem cell (CSC)-like properties in gastric cancer cells by the enhancement of growth differentiation factor 15 (GDF15) expression, i.e., S100A4 binds to the GDF15 promoter to induce CSC-like properties in gastric cancer cells, including the formation of spheroid and soft-agar colonies [ 91 ].…”