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Secreted tyrosine sulfated-eIF5A mediates oxidative stress-induced apoptosis.

Seko Y, Fujimura T, Yao T, Taka H, Mineki R, Okumura K, Murayama K - Sci Rep (2015)

Bottom Line: It causes cell damage that leads to apoptosis via uncertain mechanisms.Myocardial ischemia/reperfusion (but not ischemia alone) markedly increased the plasma levels of eIF5A, and treatment with anti-eIF5A neutralizing mAbs significantly reduced myocardial injury.These results identify an important, novel specific biomarker and a critical therapeutic target for oxidative stress-induced cell injury.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Medicine, The Institute for Adult Diseases, Asahi Life Foundation, 2-2-6 Nihonbashi-Bakurocho, Chuo-ku, Tokyo 103-0002, Japan.

ABSTRACT
Oxidative stress plays a critical role in ischemia/reperfusion-injury, atherosclerosis, and aging. It causes cell damage that leads to apoptosis via uncertain mechanisms. Because conditioned medium from cardiac myocytes subjected to hypoxia/reoxygenation induces extensive apoptosis of cardiac myocytes under normoxia, we hypothesized that a humoral factor released from the hypoxic/reoxygenated cardiac myocytes mediates apoptosis. We identified an apoptosis-inducing humoral factor in the hypoxia/reoxygenation-conditioned medium. Here, we found that eIF5A undergoes tyrosine sulfation in the trans-Golgi and is rapidly secreted from cardiac myocytes in response to hypoxia/reoxygenation; then, eIF5A induces apoptosis by acting as a pro-apoptotic ligand. The apoptosis of cardiac myocytes induced by hypoxia/reoxygenation or ultraviolet irradiation was suppressed by anti-eIF5A neutralizing monoclonal antibodies (mAbs) in vitro. Myocardial ischemia/reperfusion (but not ischemia alone) markedly increased the plasma levels of eIF5A, and treatment with anti-eIF5A neutralizing mAbs significantly reduced myocardial injury. These results identify an important, novel specific biomarker and a critical therapeutic target for oxidative stress-induced cell injury.

No MeSH data available.


Related in: MedlinePlus

Identification of the structural modifications present in the secreted form of eIF5A.(a–c) Extracted ion chromatogram of the +3 charge state of the apparent tryptic peptide of residues 68–85 (KYEDICPSTHNMDVPNIK + 80 Da) of eIF-5A (a) and that of the corresponding theoretically sulfated (b) and phosphorylated (c) peptides. The spectrum (a) was extracted from the full mass chromatogram (m/z 350–2000). The lower two theoretical spectra were calculated as the tryptic peptide plus SO3 (b) or HPO3 (c) based on the element composition. (d) The +3 charge state for MS/MS of the apparently sulfated peptide of residues 68–85 (m/z 728.52). (e) Western blot analysis of cytosolic and secreted re-eIF5A for tyrosine sulfation (upper panel) and eIF5A (lower panel) using YSP5-45-36. (f) Effects of hypoxia (60 min)/reoxygenation on the translocation of eIF5A to the trans-Golgi (labeled with syntaxin 6 [lower panel]) and on tyrosine sulfation (upper panel) or on the localization of eIF5A (middle panel) using YSP5-45-36.
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f2: Identification of the structural modifications present in the secreted form of eIF5A.(a–c) Extracted ion chromatogram of the +3 charge state of the apparent tryptic peptide of residues 68–85 (KYEDICPSTHNMDVPNIK + 80 Da) of eIF-5A (a) and that of the corresponding theoretically sulfated (b) and phosphorylated (c) peptides. The spectrum (a) was extracted from the full mass chromatogram (m/z 350–2000). The lower two theoretical spectra were calculated as the tryptic peptide plus SO3 (b) or HPO3 (c) based on the element composition. (d) The +3 charge state for MS/MS of the apparently sulfated peptide of residues 68–85 (m/z 728.52). (e) Western blot analysis of cytosolic and secreted re-eIF5A for tyrosine sulfation (upper panel) and eIF5A (lower panel) using YSP5-45-36. (f) Effects of hypoxia (60 min)/reoxygenation on the translocation of eIF5A to the trans-Golgi (labeled with syntaxin 6 [lower panel]) and on tyrosine sulfation (upper panel) or on the localization of eIF5A (middle panel) using YSP5-45-36.

Mentions: To identify the type and amino acid site of this eIF5A modification, we analyzed purified secreted and cytosolic re-eIF5A via nanoLC-LTQ orbitrap MS. The molecular weight of the peptide corresponding to residues 68–85 was 80 Da higher than expected (Fig. 2a–c). Candidate modifications to explain this 80 Da increase included phosphorylation and sulfation. Figure 2a–c shows the +3 charge state mass spectra of the apparently (m/z = 728.65180, Fig. 2a) and theoretically (m/z = 728.65172, Fig. 2b) sulfated and the theoretically phosphorylated (m/z = 728.65489, Fig. 2c) tryptic peptides. Because the mass of (a) was much closer to (b) than to (c), we identified this modification as sulfation.


Secreted tyrosine sulfated-eIF5A mediates oxidative stress-induced apoptosis.

Seko Y, Fujimura T, Yao T, Taka H, Mineki R, Okumura K, Murayama K - Sci Rep (2015)

Identification of the structural modifications present in the secreted form of eIF5A.(a–c) Extracted ion chromatogram of the +3 charge state of the apparent tryptic peptide of residues 68–85 (KYEDICPSTHNMDVPNIK + 80 Da) of eIF-5A (a) and that of the corresponding theoretically sulfated (b) and phosphorylated (c) peptides. The spectrum (a) was extracted from the full mass chromatogram (m/z 350–2000). The lower two theoretical spectra were calculated as the tryptic peptide plus SO3 (b) or HPO3 (c) based on the element composition. (d) The +3 charge state for MS/MS of the apparently sulfated peptide of residues 68–85 (m/z 728.52). (e) Western blot analysis of cytosolic and secreted re-eIF5A for tyrosine sulfation (upper panel) and eIF5A (lower panel) using YSP5-45-36. (f) Effects of hypoxia (60 min)/reoxygenation on the translocation of eIF5A to the trans-Golgi (labeled with syntaxin 6 [lower panel]) and on tyrosine sulfation (upper panel) or on the localization of eIF5A (middle panel) using YSP5-45-36.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562266&req=5

f2: Identification of the structural modifications present in the secreted form of eIF5A.(a–c) Extracted ion chromatogram of the +3 charge state of the apparent tryptic peptide of residues 68–85 (KYEDICPSTHNMDVPNIK + 80 Da) of eIF-5A (a) and that of the corresponding theoretically sulfated (b) and phosphorylated (c) peptides. The spectrum (a) was extracted from the full mass chromatogram (m/z 350–2000). The lower two theoretical spectra were calculated as the tryptic peptide plus SO3 (b) or HPO3 (c) based on the element composition. (d) The +3 charge state for MS/MS of the apparently sulfated peptide of residues 68–85 (m/z 728.52). (e) Western blot analysis of cytosolic and secreted re-eIF5A for tyrosine sulfation (upper panel) and eIF5A (lower panel) using YSP5-45-36. (f) Effects of hypoxia (60 min)/reoxygenation on the translocation of eIF5A to the trans-Golgi (labeled with syntaxin 6 [lower panel]) and on tyrosine sulfation (upper panel) or on the localization of eIF5A (middle panel) using YSP5-45-36.
Mentions: To identify the type and amino acid site of this eIF5A modification, we analyzed purified secreted and cytosolic re-eIF5A via nanoLC-LTQ orbitrap MS. The molecular weight of the peptide corresponding to residues 68–85 was 80 Da higher than expected (Fig. 2a–c). Candidate modifications to explain this 80 Da increase included phosphorylation and sulfation. Figure 2a–c shows the +3 charge state mass spectra of the apparently (m/z = 728.65180, Fig. 2a) and theoretically (m/z = 728.65172, Fig. 2b) sulfated and the theoretically phosphorylated (m/z = 728.65489, Fig. 2c) tryptic peptides. Because the mass of (a) was much closer to (b) than to (c), we identified this modification as sulfation.

Bottom Line: It causes cell damage that leads to apoptosis via uncertain mechanisms.Myocardial ischemia/reperfusion (but not ischemia alone) markedly increased the plasma levels of eIF5A, and treatment with anti-eIF5A neutralizing mAbs significantly reduced myocardial injury.These results identify an important, novel specific biomarker and a critical therapeutic target for oxidative stress-induced cell injury.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Medicine, The Institute for Adult Diseases, Asahi Life Foundation, 2-2-6 Nihonbashi-Bakurocho, Chuo-ku, Tokyo 103-0002, Japan.

ABSTRACT
Oxidative stress plays a critical role in ischemia/reperfusion-injury, atherosclerosis, and aging. It causes cell damage that leads to apoptosis via uncertain mechanisms. Because conditioned medium from cardiac myocytes subjected to hypoxia/reoxygenation induces extensive apoptosis of cardiac myocytes under normoxia, we hypothesized that a humoral factor released from the hypoxic/reoxygenated cardiac myocytes mediates apoptosis. We identified an apoptosis-inducing humoral factor in the hypoxia/reoxygenation-conditioned medium. Here, we found that eIF5A undergoes tyrosine sulfation in the trans-Golgi and is rapidly secreted from cardiac myocytes in response to hypoxia/reoxygenation; then, eIF5A induces apoptosis by acting as a pro-apoptotic ligand. The apoptosis of cardiac myocytes induced by hypoxia/reoxygenation or ultraviolet irradiation was suppressed by anti-eIF5A neutralizing monoclonal antibodies (mAbs) in vitro. Myocardial ischemia/reperfusion (but not ischemia alone) markedly increased the plasma levels of eIF5A, and treatment with anti-eIF5A neutralizing mAbs significantly reduced myocardial injury. These results identify an important, novel specific biomarker and a critical therapeutic target for oxidative stress-induced cell injury.

No MeSH data available.


Related in: MedlinePlus