THESIS
2007
xix, 168 leaves : ill. (some col.) ; 30 cm
Abstract
Chemokine receptors are members of the seven-transmembrane-domain G protein-coupled receptors. Previous studies have shown that CC chemokine receptors, such as CCR1 and CCR2b, could utilize Gα
14 and Gα
16 to activate phospholipase Cβ (PLCβ) and induce extracellular signal-regulated kinase (ERK) phosphorylation via Gα
14 in cotransfection systems. The aim of this research is to investigate whether CCR1-mediated Gα
14 or Gα
16 activation can modulate the activities of other mitogen-activated protein kinases (MAPKs), signal transducer and activator of transcription 3 (STAT3), inhibitor κB kinase (IKK) and nuclear factor κB (NF-κB) in cotransfected HEK293 cells, and chemotaxis of monocytic THP-1 cells expressing CCR1, CCR2b, Gα
14 and Gα
16. The phosphorylations of c-Jun N-terminal kinase (JNK),...[
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Chemokine receptors are members of the seven-transmembrane-domain G protein-coupled receptors. Previous studies have shown that CC chemokine receptors, such as CCR1 and CCR2b, could utilize Gα
14 and Gα
16 to activate phospholipase Cβ (PLCβ) and induce extracellular signal-regulated kinase (ERK) phosphorylation via Gα
14 in cotransfection systems. The aim of this research is to investigate whether CCR1-mediated Gα
14 or Gα
16 activation can modulate the activities of other mitogen-activated protein kinases (MAPKs), signal transducer and activator of transcription 3 (STAT3), inhibitor κB kinase (IKK) and nuclear factor κB (NF-κB) in cotransfected HEK293 cells, and chemotaxis of monocytic THP-1 cells expressing CCR1, CCR2b, Gα
14 and Gα
16. The phosphorylations of c-Jun N-terminal kinase (JNK), p38 MAPK, STAT3, IKK and NF-κB was identified by Western blotting analysis while cell migration was determined using transwell chemotaxis plate. It was found that both CCR1 and CCR2b-mediated chemotaxis could not be completely blocked by pertussis toxin (PTX) pretreatment in THP-1 cells, suggesting the involvement of PTX-insensitive G proteins. CCR1 and CCR2b agonists were less efficacious in mediating PTX-insensitive chemotaxis of THP-1 cells transfected with small interfering RNA (siRNA) against Gα
16, showing the participation of G
16 in CCR1 and CCR2b agonist-induced cell migration. The CCR1 agonist also activated chemotaxis of PMA-pretreated Jurkat T cells and butyric acid-pretreated HL-60 leukemic cells. The cell movement was resistant to PTX pretreatment in both cells, demonstrating the involvement of PTX-insensitive G proteins. In addition, it was illustrated that CCR1 could activate JNK, p38 MAPK, IKK, NF-κB and STAT3 at both Tyr
705 and Ser
727 via G
14 and G
16 in cotransfected HEK293 cells. The CCR1 agonist-enhanced phosphorylations of IKK and STAT3 at Tyr
705 through G
14 and G
16 was dependent on Raf-1, mitogen-activated protein kinase kinase 1/2, PLCβ, protein kinase C, calmodulin, calmodulin-dependent kinase II and c-Src. The restrictive expression of G
14 and G
16 may facilitate chemokines to induce local expression of cytokine or chemokine genes in specific organs or tissues.
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