title: Thymosin β4 activates integrin-linked kinase and decreases endothelial progenitor cells apoptosis under serum deprivation.
abstract: Thymosin β4 (Tβ4) has been suggested to regulate multiple cell signal pathways and a variety of cellular functions such as cell migration, proliferation, survival, and angiogenesis. Here, we investigated the effect of Tβ4 on endothelial progenitor cells (EPCs) apoptosis induced by serum deprivation and the corresponding signal transduction pathways involved in this process. Circulating EPCs, isolated from healthy volunteers, were cultured in the absence or presence of Tβ4 and various signal cascade inhibitors. Apoptosis was evaluated with Annexin V immunostaining and cytosolic cytochrome c expression. Incubation of EPCs with Tβ4 caused a concentration dependent increase in cell viability and proliferation activity. It also caused an inhibitory effect on EPCs apoptosis, which was abolished by PI3K inhibitors (either LY294002 or Wortmannin) or JNK MAPK inhibitor SP600125. In addition, the expression and activity of caspase-3 and -9 were decreased by Tβ4, which markedly increased the Bcl-2/Bax ratio within EPCs. Furthermore, Tβ4 was immunoprecipitated with integrin-linked kinase (ILK), accompanied by augmentation of ILK activity. Transfection of EPCs with ILK-siRNA resulted in abolishment of the activation of ILK-Akt and the ameliorative effect on apoptosis by Tβ4. Together, Tβ4 mediated inhibitory effect on EPCs apoptosis under serum deprivation can be attributed, at least in part, to ILK-Akt activation. The activation of JNK MAPK might also be involved in this process.
authors.affiliation: Department of Cardiology, Biomedical Research (Therapy) Center, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China.
authors.forename: Yanbo
authors.initials: Y
authors.lastname: Zhao
authors.forename: Fuyu
authors.initials: F
authors.lastname: Qiu
authors.forename: Shengjie
authors.initials: S
authors.lastname: Xu
authors.forename: Lu
authors.initials: L
authors.lastname: Yu
authors.forename: Guosheng
authors.initials: G
authors.lastname: Fu
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D017304:Annexin A5 / Q000032:analysis; D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000096:biosynthesis; D053453:Caspase 9 / Q000096:biosynthesis; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D016895:Culture Media, Serum-Free; D045304:Cytochromes c / Q000096:biosynthesis; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D009025:Morpholines / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013234:Stem Cells / Q000187:drug effects* / Q000201:enzymology; D013947:Thymosin / Q000494:pharmacology*; D000077191:Wortmannin; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D000099201:Thymosin beta(4); D000099200:Scaffold Protein ILK
chemical_list: D000730:Androstadienes; D017304:Annexin A5; D000873:Anthracenes; D053148:Caspase 3; D053453:Caspase 9; D002867:Chromones; D016895:Culture Media, Serum-Free; D045304:Cytochromes c; D004791:Enzyme Inhibitors; D009025:Morpholines; D017346:Protein Serine-Threonine Kinases; D019253:Proto-Oncogene Proteins c-bcl-2; D013947:Thymosin; D000077191:Wortmannin; D051028:bcl-2-Associated X Protein; D000099201:Thymosin beta(4); D000099200:Scaffold Protein ILK; C494826:BAX protein, human; C432165:pyrazolanthrone; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one