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Blood, 4 June 2009, Vol. 113, No. 23, pp. 6023-6033. Prepublished online as a Blood First Edition Paper on April 6, 2009; DOI 10.1182/blood-2008-10-183210.
Submitted October 7, 2008
Department of Physiology, The University of Tennessee Health Science Center, Memphis, TN, United States * Corresponding author; email: grao{at}physio1.utmem.edu.
To understand the molecular basis underlying 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE)-induced angiogenesis, we have studied the role of the Janus kinase-signal transducer and activator of transcription (Jak-STAT) signaling. 15(S)-HETE stimulated tyrosine phosphorylation of Jak2 in a time-dependent manner in human retinal microvascular endothelial cells (HRMVEC). Inhibition of Jak2 activation via adenovirus-mediated expression of its dominant negative mutant attenuated 15(S)-HETE-induced HRMVEC migration and tube formation and Matrigel plug angiogenesis. Similarly, 15(S)-HETE activated tyrosine phosphorylation of STAT-5B in a time-dependent manner. Dominant negative mutant-mediated interference of STAT-5B activation suppressed 15(S)-HETE-induced HRMVEC migration and tube formation and Matrigel plug angiogenesis. 15(S)-HETE induced interleukin-8 (IL-8) expression in Jak2-STAT-5B-dependent manner in HRMVEC. In addition, neutralizing anti-IL-8 antibodies reduced 15(S)-HETE-induced HRMVEC migration and tube formation and Matrigel plug angiogenesis. Cloning and Transfac analysis of IL-8 promoter revealed the presence of one putative STAT-binding sequence at -476 nt and EMSA and CHIP analysis showed the binding STAT-5B to this site in response to 15(S)-HETE. Mutational analysis showed that STAT-binding site is essential for 15(S)-HETE-induced IL-8 promoter activity. Together, these observations suggest that 15(S)-HETE-induced angiogenesis requires Jak2-STAT-5B-dependent expression of IL-8.
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