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Articles by K. R Chava
Total Records ( 2 ) for K. R Chava
  K. R Chava , M Karpurapu , D Wang , M Bhanoori , V Kundumani Sridharan , Q Zhang , T Ichiki , W. C Glasgow and G. N. Rao
 

Objective— Migration of vascular smooth muscle cells (VSMCs) from media to intima is a key event in the pathophysiology of atherosclerosis and restenosis. The lipoxygenase products of polyunsaturated fatty acids (PUFA) were shown to play a role in these diseases. cAMP response element binding protein (CREB) has been implicated in the regulation of VSMC growth and motility in response to thrombin and angiotensin II. The aim of the present study was to test the role of CREB in an oxidized lipid molecule, 15(S)-HETE–induced VSMC migration and neointima formation.

Methods and Results— 15(S)-HETE stimulated VSMC migration in CREB-dependent manner, as measured by the modified Boyden chamber method. Blockade of MEK1, JNK1, or p38MAPK inhibited 15(S)-HETE–induced CREB phosphorylation and VSMC migration. 15(S)-HETE induced expression and secretion of interleukin-6 (IL-6), as analyzed by RT-PCR and ELISA, respectively. Neutralizing anti–IL-6 antibodies blocked 15(S)-HETE–induced VSMC migration. Dominant-negative mutant-mediated blockade of ERK1/2, JNK1, p38MAPK, or CREB suppressed 15(S)-HETE–induced IL-6 expression in VSMCs. Serial 5' deletions and site-directed mutagenesis of IL-6 promoter along with chromatin immunoprecipitation using anti-CREB antibodies showed that cAMP response element is essential for 15(S)-HETE–induced IL-6 expression. Dominant-negative CREB also suppressed balloon injury–induced IL-6 expression, SMC migration from media to intimal region, and neointima formation. Adenovirus-mediated transduction of 15-lipoxygenase 2 (15-LOX2) caused increased production of 15-HETE in VSMCs and enhanced IL-6 expression, SMC migration from media to intimal region, and neointima formation in response to arterial injury.

Conclusions— The above results suggest a role for 15-LOX2–15-HETE in the regulation of VSMC migration and neointima formation involving CREB-mediated IL-6 expression.

  S. Y Cheranov , D Wang , V Kundumani Sridharan , M Karpurapu , Q Zhang , K. R Chava and G. N. Rao
 

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. The 15(S)-HETE stimulated tyrosine phosphorylation of Jak2 in a time-dependent manner in human retinal microvascular endothelial cells (HRMVECs). 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. The 15(S)-HETE induced interleukin-8 (IL-8) expression in Jak2-STAT-5B–dependent manner in HRMVECs. 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 1 putative STAT-binding sequence at –476 nt, and electrophoretic mobility shift assay and chromatin immunoprecipitation analysis showed the binding of 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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