Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A major function of Rac2 in neutrophils is the regulation of oxidant production important in bacterial killing. Rac and the related GTPase Cdc42 also regulate the dynamics of the actin cytoskeleton, necessary for leukocyte chemotaxis and phagocytosis of microorganisms. Although these GTPases appear to be critical downstream components of chemoattractant receptor signaling in human neutrophils, the pathways involved in direct control of Rac/Cdc42 activation remain to be determined. We describe an assay that measures the formation of Rac-GTP and Cdc42-GTP based on their specific binding to the p21-binding domain of p21-activated kinase 1. A p21-binding domain glutathione S-transferase fusion protein specifically binds Rac and Cdc42 in their GTP-bound forms both in vitro and in cell samples. Binding is selective for Rac and Cdc42 versus RhoA. Using this assay, we investigated Rac and Cdc42 activation in neutrophils and differentiated HL-60 cells. The chemoattractant fMet-Leu-Phe and the phorbol ester phorbol myristate acetate stimulate formation of Rac-GTP and Cdc42-GTP with distinct time courses that parallel cell activation. We also show that the signaling pathways leading to Rac and Cdc42 activation in HL-60 cells involve G proteins sensitive to pertussis toxin, as well as tyrosine kinase and phosphatidylinositol 3-kinase activities.
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PMID:Characterization of rac and cdc42 activation in chemoattractant-stimulated human neutrophils using a novel assay for active GTPases. 1022 76

Signalling via m3 and m2 receptors in smooth muscles involved activation of two G-protein-dependent pathways by each receptor. m2 receptors were coupled via Gbetagammai3 with activation of phospholipase C-beta3, phosphoinositide 3-kinase and Cdc42/Rac1 (where Cdc stands for cell division cycle) and p21-activated kinase 1 (PAK1), resulting in phosphorylation and inactivation of myosin light chain kinase (MLCK). Each step was inhibited by methoctramine and pertussis toxin. PAK1 activity was abolished in cells expressing both Cdc42-DN (where DN stands for dominant negative) and Rac1-DN. MLCK phosphorylation was inhibited by PAK1 antibody, and in cells expressing Cdc42-DN and Rac1-DN. m3 receptors were coupled via Galpha(q/11) with activation of phospholipase C-beta1 and via RhoA with activation of Rho-associated kinase (Rho kinase), phospholipase D and protein kinase C (PKC). Rho kinase and phospholipase D activities were inhibited by C3 exoenzyme and in cells expressing RhoA-DN. PKC activity was inhibited by bisindolylmaleimide, and in cells expressing RhoA-DN; PKC activity was also inhibited partly by Y27632 (44+/-5%). PKC-induced phosphorylation of PKC-activated 17 kDa inhibitor protein of type 1 phosphatase (CPI-17) at Thr38 was abolished by bisindolylmaleimide and inhibited partly by Y27632 (28+/-3%). Rho-kinase-induced phosphorylation of myosin phosphatase targeting subunit (MYPT1) and was abolished by Y27632. Sustained phosphorylation of 20 kDa regulatory light chain of myosin II (MLC20) and contraction were abolished by bisindolylmaleimide Y27632 and C3 exoenzyme and in cells expressing RhoA-DN. The results suggest that Rho-kinase-dependent phosphorylation of MYPT1 and PKC-dependent phosphorylation and enhancement of CPI-17 binding to the catalytic subunit of MLC phosphatase (MLCP) act co-operatively to inhibit MLCP activity, leading to sustained stimulation of MLC20 phosphorylation and contraction. Because Y27632 inhibited both Rho kinase and PKC activities, it could not be used to ascertain the contribution of MYPT1 to inhibition of MLCP activity. m2-dependent phosphorylation and inactivation of MLCK precluded its involvement in sustained MLC20 phosphorylation and contraction.
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PMID:Differential signalling by muscarinic receptors in smooth muscle: m2-mediated inactivation of myosin light chain kinase via Gi3, Cdc42/Rac1 and p21-activated kinase 1 pathway, and m3-mediated MLC20 (20 kDa regulatory light chain of myosin II) phosphorylation via Rho-associated kinase/myosin phosphatase targeting subunit 1 and protein kinase C/CPI-17 pathway. 1273 88

Kaposi's sarcoma-associated herpes virus (KSHV) contributes to the pathogenesis of Kaposi's sarcoma and primary effusion lymphomas. KSHV encodes a G protein-coupled receptor (KSHV-GPCR) that signals constitutively and transforms NIH3T3 cells. Here, we show that KSHV-GPCR transformation requires activation of the small G protein Rac1 and its effector, the p21-activated kinase 1 (Pak1). Either transient or sustained expression of KSHV-GPCR activated both Rac1 and Pak1. Furthermore, expression of dominant-negative mutants of Rac (RacN17) or Pak1 (PakR299, Pak-PID) inhibited KSHV-GPCR-induced focus formation and growth in soft agar. We also demonstrate that signaling from Pak1 to nuclear factor-kappaB (NFkappaB) is required for cell transformation induced by KSHV-GPCR. KSHV-GPCR induced transcriptional activation by NFkappaB. This process is inhibited by the PAK-PID, whereas reciprocally, expression of constitutively active Pak1 (PakL107F) activated NFkappaB comparably to KSHV-GPCR. The Pak-PID and RacN17 inhibited the KSHV-GPCR-induced phosphorylation of inhibitor of kappaB kinase-beta and inhibitor of kappaB-alpha, implying that it is Pak1-dependent phosphorylation and subsequent destruction of the inhibitor of kappaB proteins that allows NFkappaB activation. Finally, experiments with the KSHV-GPCR inverse agonist interferon-gamma-inducible protein-10, the Galpha(i) inhibitor pertussis toxin, and an inhibitor of phosphatidylinositol 3'-kinase, wortmannin, indicate that signaling through the Galpha(i) pathway and phosphatidylinositol 3'-kinase contributes to the cell transformation and NFkappaB activation induced by the KSHV-GPCR.
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PMID:Activation of p21-activated kinase 1-nuclear factor kappaB signaling by Kaposi's sarcoma-associated herpes virus G protein-coupled receptor during cellular transformation. 1469

Lysophosphatidic acid (LPA), one of the naturally occurring phospholipids, stimulates cell motility through the activation of Rho family members, but the signaling mechanisms remain to be elucidated. In the present study, we investigated the roles of p21-activated kinase 1 (PAK1) on LPA-induced focal adhesion kinase (FAK) phosphorylation and cell motility. Treatment of human melanoma cells A2058 with LPA increased phosphorylation and activation of PAK1, which was blocked by treatment with pertussis toxin and by inhibition of phosphoinositide 3-kinase (PI3K) with an inhibitor LY294002 or by overexpression of catalytically inactive mutant of PI3Kgamma, indicating that LPA-induced PAK1 activation was mediated via a Gi protein and the PI3Kgamma signaling pathway. In addition, we demonstrated that Rac1/Cdc42 signals acted as upstream effector molecules of LPA-induced PAK activation. However, Rho-associated kinase, MAP kinase kinase 1/2 or phospholipase C might not be involved in LPA-induced PAK1 activation or cell motility stimulation. Furthermore, PAK1 was necessary for FAK phosphorylation by LPA, which might cause cell migration, as transfection of the kinase deficient mutant of PAK1 or PAK auto-inhibitory domain significantly abrogated LPA-induced FAK phosphorylation. Taken together, these findings strongly indicated that PAK1 activation was necessary for LPA-induced cell motility and FAK phosphorylation that might be mediated by sequential activation of Gi protein, PI3Kgamma and Rac1/Cdc42.
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PMID:Activation of p21-activated kinase 1 is required for lysophosphatidic acid-induced focal adhesion kinase phosphorylation and cell motility in human melanoma A2058 cells. 1506 81

We investigated whether plasma long-chain sphingoid base (LCSB) concentrations are altered by transient cardiac ischemia during percutaneous coronary intervention (PCI) in humans and examined the signaling through the sphingosine-1-phosphate (S1P) cascade as a mechanism underlying the S1P cardioprotective effect in cardiac myocytes. Venous samples were collected from either the coronary sinus (n = 7) or femoral vein (n = 24) of 31 patients at 1 and 5 min and 12 h, following induction of transient myocardial ischemia during elective PCI. Coronary sinus levels of LCSB were increased by 1,072% at 1 min and 941% at 5 min (n = 7), while peripheral blood levels of LCSB were increased by 579% at 1 min, 617% at 5 min, and 436% at 12 h (n = 24). In cultured cardiac myocytes, S1P, sphingosine (SPH), and FTY720, a sphingolipid drug candidate, showed protective effects against CoCl induced hypoxia/ischemic cell injury by reducing lactate dehydrogenase activity. Twenty-five nanomolars of FTY720 significantly increased phospho-Pak1 and phospho-Akt levels by 56 and 65.6% in cells treated with this drug for 15 min. Further experiments demonstrated that FTY720 triggered nitric oxide release from cardiac myocytes is through pertussis toxin-sensitive phosphatidylinositol 3-kinase/Akt/endothelial nitric oxide synthase signaling. In ex vivo hearts, ischemic preconditioning was cardioprotective in wild-type control mice (Pak1(f/f)), but this protection appeared to be ineffective in cardiomyocyte-specific Pak1 knockout (Pak1(cko)) hearts. The present study provides the first direct evidence of the behavior of plasma sphingolipids following transient cardiac ischemia with dramatic and early increases in LCSB in humans. We also demonstrated that S1P, SPH, and FTY720 have protective effects against hypoxic/ischemic cell injury, likely a Pak1/Akt1 signaling cascade and nitric oxide release. Further study on a mouse model of cardiac specific deletion of Pak1 demonstrates a crucial role of Pak1 in cardiac protection against ischemia/reperfusion injury.
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PMID:Activation of Pak1/Akt/eNOS signaling following sphingosine-1-phosphate release as part of a mechanism protecting cardiomyocytes against ischemic cell injury. 2170 77