Activation of signal transducers and activators of transcription induced by vascular endothelial growth factor in CD34+ hematopoietic progenitor cells in vitro / 中国医学科学院学报
Acta Academiae Medicinae Sinicae
; (6): 12-17, 2004.
Article
em Zh
| WPRIM
| ID: wpr-326992
Biblioteca responsável:
WPRO
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the activation pattern of signal transducers and activators of transcription (STAT) induced by vascular endothelial growth factor (VEGF) in CD34+ hematopoietic progenitor cells, and gain an insight into the molecular mechanism and signal transduction pathway of VEGF that has an effect on CD34+ hematopoietic progenitor cells.</p><p><b>METHODS</b>After isolated from umbilical cord blood by using a high-gradient magnetically activated cell sorting system (MACS), CD34+ cells were stimulated by VEGF (50 ng/ml) for different time (0, 15, 30, 45, 60, 90 min) to detect the tyrosine phosphorylation and nuclear translocation of STAT-3 and STAT-5 with Western blot and immunocytochemistry methods. The expression of VEGF receptor-2 (VEGFR2) on the membrane of CD34+ progenitor cells was examined by immunocytochemistry. ATWLPPR, an effective peptide screened from phage epitope library by affinity for membrane-expressed VEGFR2 and blocking the binding of VEGF to VEGFR2, was used to determine whether the activation of STAT pathway induced by VEGF was blocked.</p><p><b>RESULTS</b>Tyrosine phosphorylation of STAT-3 and STAT-5 was undetectable in unstimulated CD34+ cells, but was evident at 15 min in response to VEGF stimulation. VEGF resulted in a rapid and transient tyrosine phosphorylation of STAT-3 and STAT-5. The maximal tyrosine phosphorylation was catched at 30 and 45 min, respectively (P = 0.0001), and returned to basal levels at 90 min. Immunocytochemistry confirmed that increased phosphorylated STAT-3 was translocated into the nuclei at 30 min (P = 0.0001), and mainly in cytoplasms again at 90 min after stimulation with VEGF. However, compared with unstimulated CD34+ cells, there was only increased phosphorylation of STAT-5 appeared mainly in cytoplasms, but no significant nuclear translocation was found after stimulation with VEGF (P > 0.05). The presence of VEGFR2 was confirmed using anti-VEGFR2 antibody staining by immunocytochemistry, moreover, the phosphorylation of STAT-3 and STAT-5 failed to be activated by the co-culture with ATWLPPR and VEGF, suggesting that activation of the STAT pathway be specifically mediated by VEGFR2 in CD34+ progenitor cells.</p><p><b>CONCLUSIONS</b>STAT signaling pathway participates in the signal transduction of VEGF via VEGFR2 in CD34+ hemopoietic progenitor cells.</p>
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Base de dados:
WPRIM
Assunto principal:
Farmacologia
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Fosforilação
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Fisiologia
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Tirosina
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Transcrição Gênica
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Células-Tronco Hematopoéticas
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Endotélio Vascular
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Transdução de Sinais
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Transativadores
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Antígenos CD34
Limite:
Adult
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Female
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Humans
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Pregnancy
Idioma:
Zh
Revista:
Acta Academiae Medicinae Sinicae
Ano de publicação:
2004
Tipo de documento:
Article