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The Extracellular Polymer Substance of Pseudomonas Aeruginosa: Too slippery for Neutrophils to Migrate On? Int J Artif Organs 2018; 31:796-803. [DOI: 10.1177/039139880803100907] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Purpose Biofilm formation is increasingly recognized as the cause of persistent infections and there is evidence that P. aeruginosa organized into biofilms are quite resistant toward host defence mechanisms, particularly against an attack by polymorphonuclear neutrophils (PMN). Apparently, the migration of PMN through the biofilms is impaired, and thus the bactericidal activity remains highly localized. The aim of this study was to directly investigate the interaction of PMN with the biofilm and the extracted extracellular polymeric substance (EPS) of P. aeruginosa. Material and Methods Chemotaxis and random migration of PMN through P. aeruginosa biofilms was tested, as was their migration through and along the EPS. Results We found that the EPS and mature biofilms, but not immature or developing ones, reduced the chemotactic migration of PMN. On EPS, rather than immobilize the cells, their random, spontaneous migration was enhanced. Conclusion We propose that on EPS, the PMN lose their capacity to sense the direction and just slide over the EPS in a disoriented manner. (Int J Artif Organs 2008; 31: 796–803)
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Lajkó E, Szabó I, Andódy K, Pungor A, Mező G, Kőhidai L. Investigation on chemotactic drug targeting (chemotaxis and adhesion) inducer effect of GnRH-III derivatives in Tetrahymena and human leukemia cell line. J Pept Sci 2012. [PMID: 23208929 DOI: 10.1002/psc.2472] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
GnRH-III has been shown to exert a cytotoxic effect on the GnRH-R positive tumor cells. The chemotactic drug targeting (CDT) represents a new way for drug delivery approach based on selective chemoattractant guided targeting. The major goal of the present work was to develop and investigate various GnRH-III derivatives as potential targeting moieties for CDT. The cell physiological effects (chemotaxis, adhesion, and signaling) induced by three native GnRHs (hGnRH-I, cGnRH-II, and lGnRH-III) and nine GnRH-III derivatives were evaluated in two model cells (Tetrahymena pyriformis and Mono Mac 6 human monocytes). According to our results, the native GnRH-III elicited the highest chemoattractant and adhesion inducer activities of all synthesized peptides in micromolar concentrations in monocytes. With respect to chemoattraction, dimeric derivatives linked by a disulfide bridge ([GnRH-III(C)](2) ) proved to be efficient in both model cells; furthermore, acetylation of the linker region ([GnRH-III(Ac-C)](2) ) could slightly improve the chemotactic and adhesion effects in monocytes. The length of the peptide and the type of N-terminal amino acid could also determine the chemotactic and adhesion modulation potency of each fragment. The application of the chemoattractant GnRH-III derivatives was accompanied by a significant activation of phosphatidylinositol 3-kinase in both model cells. In summary, our work on low-level differentiated model cells of tumors has proved that GnRH-III and some of its synthetic derivatives are promising candidates to be applied in CDT: these compounds might act both as carrier, delivery unit, and antitumor agents.
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Affiliation(s)
- Eszter Lajkó
- Department of Genetics Cell and Immunobiology, Semmelweis University, Nagyvárad tér. 4, H-1089, Budapest, Hungary
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Nakamae-Akahori M, Kato T, Masuda S, Sakamoto E, Kutsuna H, Hato F, Nishizawa Y, Hino M, Kitagawa S. Enhanced neutrophil motility by granulocyte colony-stimulating factor: the role of extracellular signal-regulated kinase and phosphatidylinositol 3-kinase. Immunology 2006; 119:393-403. [PMID: 16903868 PMCID: PMC1819568 DOI: 10.1111/j.1365-2567.2006.02448.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The effect of granulocyte colony-stimulating factor (G-CSF) on human neutrophil motility was studied using videomicroscopy. Stimulation of neutrophils with G-CSF resulted in enhanced motility with morphological change and increased adherence. Enhanced neutrophil motility was detected within 3-5 min after G-CSF stimulation, reached a maximum at 10 min, and was sustained for approximately 35 min. The maximum migration rate was 84.4 +/- 2.9 microm/5 min. A study using the Boyden chamber method revealed that G-CSF-stimulated neutrophils exhibited random migration but not chemotaxis. Enhanced neutrophil motility and morphological change were inhibited by MEK [mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase] inhibitors (PD98059 and U0126), and a phosphatidylinositol 3-kinase (PI3K) inhibitor (wortmannin), but not by a p38 MAPK inhibitor (SB203580). These findings are consistent with the fact that G-CSF selectively activates MEK/ERK and PI3K, but not p38, in neutrophils. MEK/ERK activation was associated with G-CSF-induced redistribution of F-actin and phosphorylated myosin light chain. Enhanced neutrophil motility was observed even in the presence of neutralizing anti-CD18 antibody, which prevented cell adherence. These findings indicate that G-CSF induces human neutrophil migration via activation of MEK/ERK and PI3K.
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Affiliation(s)
- Mika Nakamae-Akahori
- Department of Physiology, Osaka City University Graduate School of Medicine, Asahi-machiAbeno-ku, Osaka, Japan
| | - Takayuki Kato
- Department of Physiology, Osaka City University Graduate School of Medicine, Asahi-machiAbeno-ku, Osaka, Japan
| | - Sayuri Masuda
- Department of Physiology, Osaka City University Graduate School of Medicine, Asahi-machiAbeno-ku, Osaka, Japan
| | - Erina Sakamoto
- Department of Physiology, Osaka City University Graduate School of Medicine, Asahi-machiAbeno-ku, Osaka, Japan
| | - Haruo Kutsuna
- Department of Physiology, Osaka City University Graduate School of Medicine, Asahi-machiAbeno-ku, Osaka, Japan
| | - Fumihiko Hato
- Department of Physiology, Osaka City University Graduate School of Medicine, Asahi-machiAbeno-ku, Osaka, Japan
| | - Yoshiki Nishizawa
- Department of Medicine, Osaka City University Graduate School of Medicine, Asahi-machiAbeno-ku, Osaka, Japan
| | - Masayuki Hino
- Department of Clinical Haematology, Osaka City University Graduate School of Medicine, Asahi-machiAbeno-ku, Osaka, Japan
| | - Seiichi Kitagawa
- Department of Physiology, Osaka City University Graduate School of Medicine, Asahi-machiAbeno-ku, Osaka, Japan
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Oka S, Sasada M, Yamamoto K, Nohgawa M, Takahashi A, Yamashita K, Yamada H, Uchiyama T. Nitric Oxide Derived from Human Umbilical Vein Endothelial Cells Inhibits Transendothelial Migration of Neutrophils. Int J Hematol 2005; 81:220-7. [PMID: 15814333 DOI: 10.1532/ijh97.04070] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We evaluated the roles of nitric oxide (NO) derived from endothelial cells in neutrophil transendothelial migration (TEM). Pretreatment of human umbilical vein endothelial cells (HUVECs) with NG-nitro-L-arginine methyl ester hydrochloride (L-NAME) or NG-monomethyl L-arginine (L-NMMA), which are inhibitors of NO synthases, enhanced neutrophil TEM. Similar augmentation of TEM was observed in the presence of an NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy PTIO). Neutrophil TEM across L-NAME- or L-NMMA-treated HUVECs was inhibited by continuous NO supply by NO donors. These findings support the suggestion that continuous production of NO by endothelial cells suppresses neutrophil TEM. Flow cytometric analyses revealed that NO accumulates in neutrophils co-cultured with NO-producing HUVECs. A decreased amount of NO was detected in neutrophils co-cultured with L-NAME-treated HUVECs compared with neutrophils co-cultured with untreated HUVECs. Soluble guanylyl cyclase (sGC) is known as one of the most important targets of NO in neutrophils. 3-(53-Hydroxymethyl-23furyl)-1-benzyl indazole (YC-1), an activator of sGC, inhibited L-NAME-induced neutrophil TEM. It was interesting that inhibition of neutrophil sGC with 1-H[1,2,4-]oxadiazolo[4,3-a]quinoxalin-1-1 (ODQ) was sufficient to enhance TEM. These results suggest that NO derived from HUVECs acts on neutrophils to inhibit TEM, at least in part by activating sGC. Our findings imply the role of NO constitutively generated by HUVECs in protection against excessive neutrophil extravasation and unnecessary tissue damage under physiological conditions.
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Affiliation(s)
- Satoshi Oka
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Japan
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5
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Gomez-Cambronero J, Horn J, Paul CC, Baumann MA. Granulocyte-macrophage colony-stimulating factor is a chemoattractant cytokine for human neutrophils: involvement of the ribosomal p70 S6 kinase signaling pathway. THE JOURNAL OF IMMUNOLOGY 2004; 171:6846-55. [PMID: 14662891 DOI: 10.4049/jimmunol.171.12.6846] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
GM-CSF stimulates proliferation of myeloid precursors in bone marrow and primes mature leukocytes for enhanced functionality. We demonstrate that GM-CSF is a powerful chemotactic and chemokinetic agent for human neutrophils. GM-CSF-induced chemotaxis is time dependent and is specifically neutralized with Abs directed to either the ligand itself or its receptor. Maximal chemotactic response was achieved at approximately 7 nM GM-CSF, and the EC(50) was approximately 0.9 nM. Both concentrations are similar to the effective concentrations of IL-8 and less than the effective concentrations of other neutrophil chemoattractants such as neutrophil-activating peptide-78, granulocyte chemotactic protein-2, leukotriene B(4), and FMLP. GM-CSF also acts as a chemoattractant for native cells bearing the GM-CSF receptor, such as monocytes, as well as for GM-CSF receptor-bearing myeloid cell lines, HL60 (promyelomonocyte leukemic cell line) and MPD (myeloproliferative disorder cell line), following differentiation induction. GM-CSF induced a rapid, transient increase in F-actin polymerization and the formation of focal contact rings in neutrophils, which are prerequisites for cell migration. The mechanism of GM-CSF-induced chemotaxis appears to involve the cell signaling molecule, ribosomal p70 S6 kinase (p70S6K). Both p70S6K enzymatic activity and T(421)/S(424) and T(389) phosphorylation are markedly increased with GM-CSF. In addition, the p70S6K inhibitor hamartin transduced into cells as active protein, interfered with GM-CSF-dependent migration, and attenuated p70S6K phosphorylation. These data indicate that GM-CSF exhibits chemotactic functionality and suggest new avenues for the investigation of the molecular basis of chemotaxis as it relates to inflammation and tissue injury.
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Yoshinaga-Ohara N, Takahashi A, Uchiyama T, Sasada M. Spatiotemporal regulation of moesin phosphorylation and rear release by Rho and serine/threonine phosphatase during neutrophil migration. Exp Cell Res 2002; 278:112-22. [PMID: 12126963 DOI: 10.1006/excr.2002.5571] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Neutrophil motility is crucial to effective host defenses against microorganisms. While uropod retraction is a critical step in the migration of neutrophils, the underlying molecular mechanism is not well understood. Here, we show that inhibition of the Rho small GTPase with C3 exoenzyme prevented the retraction of trailing uropods, indicating that the process of rear release is mediated by a Rho signaling pathway. C3 exoenzyme caused marked elongation of directionally migrating neutrophils, suggesting an additional role for Rho in the maintenance of functional polarized cell shape. We also show that phosphorylation and dephosphorylation of the plasma membrane-actin filament cross-linker moesin are spatiotemporally controlled in migrating neutrophils. In particular, phosphorylation of moesin at threonine 558 depended on Rho activity. Videomicroscopy showed that dephosphorylation of this carboxy-terminal threonine preceded uropod retraction. Calyculin A, an inhibitor of type 1 and type 2A serine/threonine phosphatases, suppressed the moesin dephosphorylation and impaired uropod retraction in a dose-dependent manner. Cypermethrin, an inhibitor of type 2B serine/threonine phosphatase, had no such effects. The finding that Rho small GTPase and type 1/type 2A phosphatases are involved in rear release yields novel insights into the biochemical mechanisms of neutrophil migration.
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Affiliation(s)
- Naoko Yoshinaga-Ohara
- Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
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Kalkman PMJ, Fokkens WJ, de Wit HJ, van de Merwe JP, Hooijkaas H, van Haarst JMW, Hoogsteden HC, Drexhage HA. A hampered chemoattractant-induced cytoskeletal rearrangement in granulocytes of patients with unexplained severe chronic and relapsing infections of the upper and lower airways. In vitro restoration by G-CSF exposure. Clin Exp Immunol 2002; 127:115-22. [PMID: 11882041 PMCID: PMC1906280 DOI: 10.1046/j.1365-2249.2002.01738.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2001] [Indexed: 11/20/2022] Open
Abstract
Granulocytes play a major role in host defense against bacterial infections. Severe inborn defects in granulocyte function are associated with fulminant bacterial infections in early childhood. Subtle disturbances in granulocyte function might contribute to an enhanced susceptibility to bacterial infections in adulthood. We investigated chemoattractant (N-formyl-methionyl-leucyl-phenylalanine, fMLP and casein) induced cytoskeletal rearrangements (polarization) of blood granulocytes in 77 adults with chronic and recurrent therapy-resistant infections of the upper and lower airways. These infections could not be explained by B- and/or T-cell defects or local anatomic abnormalities. Besides polarization, chemotaxis of blood granulocytes was measured in 33 patients, as well as granulocyte superoxide production in eight patients. The chemoattractant-induced cytoskeletal rearrangement in patient blood granulocytes was significantly lower as compared to healthy control values with both fMLP and casein as stimuli. About two-thirds of the patients showed a defective polarization response to fMLP. Granulocyte colony-stimulating factor (G-CSF) when added in vitro corrected the defective polarization responses; responses in the normal range were not enhanced. The chemotactic motility of patient blood granulocytes was also slightly, but significantly lowered. However, it did not correlate to the lowered polarization. Granulocyte superoxide production was comparable in patients and in healthy controls. Our data thus show that subtle abnormalities in chemoattractant-induced cytoskeletal and motile function of blood granulocytes are frequent in patients with severe therapy-refractory bacterial infections of the upper and lower airways.
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Affiliation(s)
- P M J Kalkman
- Department of Immunology, Eramus University and University Hospital Dijkzigt, Rotterdam, The Netherlands
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Nijhuis E, Lammers JJ, Koenderman L, Coffer PJ. Src kinases regulate PKB activation and modulate cytokine and chemoattractant‐controlled neutrophil functioning. J Leukoc Biol 2002. [DOI: 10.1189/jlb.71.1.115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Evert Nijhuis
- Department of Pulmonary Diseases, G03.550, University Medical Centre Utrecht, The Netherlands
| | - Jan‐Willem J Lammers
- Department of Pulmonary Diseases, G03.550, University Medical Centre Utrecht, The Netherlands
| | - Leo Koenderman
- Department of Pulmonary Diseases, G03.550, University Medical Centre Utrecht, The Netherlands
| | - Paul J. Coffer
- Department of Pulmonary Diseases, G03.550, University Medical Centre Utrecht, The Netherlands
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Flaishon L, Lantner F, Hershkoviz R, Levo Y, Shachar I. Low levels of IFN-gamma down-regulate the integrin-dependent adhesion of B cells by activating a pathway that interferes with cytoskeleton rearrangement. J Biol Chem 2001; 276:46701-6. [PMID: 11585817 DOI: 10.1074/jbc.m103484200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In order to fully mature and participate in the humoral immune response, immature B cells must first migrate into specific areas in the spleen where they differentiate into mature cells. However, before their maturation in the spleen, immature B cells must be excluded from non-splenic secondary lymphoid organs where any antigen encounter would lead to the death of the cells because of the negative selection process. We have recently shown that immature B cells can actively exclude themselves from antigen-enriched sites by down-regulating their integrin-mediated adhesion in a process mediated by interferon-gamma (IFN-gamma). In this study, we followed the pathway by which IFN-gamma regulates the homing of B cells. We show here that the inhibitory signal of IFN-gamma is transmitted through the IFN-gamma receptor whose engagement leads to the activation of PI3K. This PI3K activation subsequently leads to the inhibition of PKCalpha phosphorylation and cytoskeleton rearrangement required for promoting integrin-mediated adhesion and migration of B cells.
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Affiliation(s)
- L Flaishon
- Department of Immunology, The Weizmann Institute of Science, Herzel St., Rehovot 76100, Israel
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Fine JS, Byrnes HD, Zavodny PJ, Hipkin RW. Evaluation of signal transduction pathways in chemoattractant-induced human monocyte chemotaxis. Inflammation 2001; 25:61-7. [PMID: 11321360 DOI: 10.1023/a:1007152903135] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The intracellular signaling pathways involved in human monocyte chemotaxis toward a variety of chemoattractant molecules were evaluated using selected pharmacological agents. Neither phosphatidylinositol-3-kinase (P13K) or extracellular signal-regulated kinase (ERK) activity were required for monocyte migration toward monocyte chemoattractant protein-1 (MCP-1), RANTES (Regulated on Activation, Normal T cell Expressed and Secreted), macrophage inflammatory protein-1alpha (MIP-1alpha) or formyl-Met-Leu-Phe (fMLP), since pretreatment with wortmannin or LY294002, or with PD098059, had no effect on the chemotactic response. Addition of forskolin and IBMX significantly attenuated chemotaxis to each of these chemoattractants and was reversed by co-treatment with Rp-cAMP, a competitive inhibitor of cAMP-dependent protein kinase A. Incubation with the protein kinase C (PKC) inhibitor GF109203X-HCl (GF109) did not affect monocyte migration, but pretreatment of monocytes with PMA significantly impaired the response to each of these chemotactic agents. Inhibition by PMA was reversed by co-treatment with GF109, implying that heterologous PKC activation is capable of desensitizing chemokine and fMLP-induced monocyte chemotaxis. These results help to define the signalling pathways involved in human monocyte chemotaxis and suggest pharmacological approaches to evaluating the cross-desensitization of chemoattractant-induced leukocyte migration.
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Affiliation(s)
- J S Fine
- Department of Immunology, Schering-Plough Research Institute, Kenilworth, New Jersey, USA
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Wu D, Huang CK, Jiang H. Roles of phospholipid signaling in chemoattractant-induced responses. J Cell Sci 2000; 113 ( Pt 17):2935-40. [PMID: 10934033 DOI: 10.1242/jcs.113.17.2935] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chemoattractants, including chemokines, play a central role in regulation of inflammatory reactions by attracting and activating leukocytes. These molecules have been found to regulate metabolism of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)) via phospholipase C (PLC) and phosphoinositide 3-kinase (PI3K). Recent studies of mouse lines that lack PLC-(beta)2, PLC-(beta)3, or PI3K(gamma) demonstrate that chemoattractants act through PLC-(beta)2 and PLC-(beta)3 to hydrolyze PtdIns(4,5)P(2) and through PI3K(gamma) to phosphorylate PtdIns(4,5)P(2) in mouse neutrophils. These studies also confirmed the importance and revealed new roles of these signaling pathways in chemoattractant-induced responses.
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Affiliation(s)
- D Wu
- Department of Genetics and Developmental Biology and Department of Pathology, University of Connecticut, Farmington, CT 06030, USA
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Miller LA, Usachenko J, McDonald RJ, Hyde DM. Trafficking of neutrophils across airway epithelium is dependent upon both thioredoxin‐ and pertussis toxin‐sensitive signaling mechanisms. J Leukoc Biol 2000. [DOI: 10.1189/jlb.68.2.201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Lisa A. Miller
- The Center for Comparative Respiratory Biology and Medicine and Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, Davis
| | - Jodie Usachenko
- The Center for Comparative Respiratory Biology and Medicine and Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, Davis
- Department of Pediatrics, School of Medicine, University of California, Davis
| | - Ruth J. McDonald
- Department of Pediatrics, School of Medicine, University of California, Davis
| | - Dallas M. Hyde
- The Center for Comparative Respiratory Biology and Medicine and Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, Davis
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Regulation of polymorphonuclear leukocyte phagocytosis by myosin light chain kinase after activation of mitogen-activated protein kinase. Blood 2000. [DOI: 10.1182/blood.v95.7.2407] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractPolymorphonuclear leukocyte (PMNL) phagocytosis mediated by FcγRII proceeds in concert with activation of the mitogen-activated protein (MAP) kinase, extracellular signal-regulated kinase ERK2. We hypothesized that myosin light chain kinase (MLCK) could be phosphorylated and activated by ERK, thereby linking the MAP kinase pathway to the activation of cytoskeletal components required for pseudopod formation. To explore this potential linkage, PMNLs were challenged with antibody-coated erythrocytes (EIgG). Peak MLCK activity, 3-fold increased over controls, occurred at 4 to 6 minutes, corresponding with the peak rate of target ingestion and ERK2 activity. The MLCK inhibitor ML-7 (10 μmol/L) inhibited both phagocytosis and MLCK activity to basal values, thereby providing further support for the linkage between the functional response and the requirement for MLCK activation. The MAPK kinase (MEK) inhibitor PD098059 inhibited phagocytosis, MLCK activity, and ERK2 activity by 80% to 90%. To directly link ERK activation to MLCK activation, ERK2 was immunoprecipitated from PMNLs after EIgG ingestion. The isolated ERK2 was incubated with PMNL cytosol as a source of unactivated MLCK and with MLCK substrate; under these conditions ERK2 activated MLCK, resulting in phosphorylation of the MLCK substrate or of the myosin light chain itself. Because MLCK activates myosin, we evaluated the effect of directly inhibiting myosin adenosine triphosphatase using 2,3-butanedione monoxime (BDM) and found that phagocytosis was inhibited by more than 90% but MLCK activity remained unaffected. These results are consistent with the interpretation that MEK activates ERK, ERK2 then activates MLCK, and MLCK activates myosin. MLCK activation is a critical step in the cytoskeletal changes resulting in pseudopod formation.
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Regulation of polymorphonuclear leukocyte phagocytosis by myosin light chain kinase after activation of mitogen-activated protein kinase. Blood 2000. [DOI: 10.1182/blood.v95.7.2407.007k02_2407_2412] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Polymorphonuclear leukocyte (PMNL) phagocytosis mediated by FcγRII proceeds in concert with activation of the mitogen-activated protein (MAP) kinase, extracellular signal-regulated kinase ERK2. We hypothesized that myosin light chain kinase (MLCK) could be phosphorylated and activated by ERK, thereby linking the MAP kinase pathway to the activation of cytoskeletal components required for pseudopod formation. To explore this potential linkage, PMNLs were challenged with antibody-coated erythrocytes (EIgG). Peak MLCK activity, 3-fold increased over controls, occurred at 4 to 6 minutes, corresponding with the peak rate of target ingestion and ERK2 activity. The MLCK inhibitor ML-7 (10 μmol/L) inhibited both phagocytosis and MLCK activity to basal values, thereby providing further support for the linkage between the functional response and the requirement for MLCK activation. The MAPK kinase (MEK) inhibitor PD098059 inhibited phagocytosis, MLCK activity, and ERK2 activity by 80% to 90%. To directly link ERK activation to MLCK activation, ERK2 was immunoprecipitated from PMNLs after EIgG ingestion. The isolated ERK2 was incubated with PMNL cytosol as a source of unactivated MLCK and with MLCK substrate; under these conditions ERK2 activated MLCK, resulting in phosphorylation of the MLCK substrate or of the myosin light chain itself. Because MLCK activates myosin, we evaluated the effect of directly inhibiting myosin adenosine triphosphatase using 2,3-butanedione monoxime (BDM) and found that phagocytosis was inhibited by more than 90% but MLCK activity remained unaffected. These results are consistent with the interpretation that MEK activates ERK, ERK2 then activates MLCK, and MLCK activates myosin. MLCK activation is a critical step in the cytoskeletal changes resulting in pseudopod formation.
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Pettit EJ, Fay FS. Cytosolic free calcium and the cytoskeleton in the control of leukocyte chemotaxis. Physiol Rev 1998; 78:949-67. [PMID: 9790567 DOI: 10.1152/physrev.1998.78.4.949] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
In response to a chemotactic gradient, leukocytes extravasate and chemotax toward the site of pathogen invasion. Although fundamental in the control of many leukocyte functions, the role of cytosolic free Ca2+ in chemotaxis is unclear and has been the subject of debate. Before becoming motile, the cell assumes a polarized morphology, as a result of modulation of the cytoskeleton by G protein and kinase activation. This morphology may be reinforced during chemotaxis by the intracellular redistribution of Ca2+ stores, cytoskeletal constituents, and chemoattractant receptors. Restricted subcellular distributions of signaling molecules, such as Ca2+, Ca2+/calmodulin, diacylglycerol, and protein kinase C, may also play a role in some types of leukocyte. Chemotaxis is an essential function of most cells at some stage during their development, and a deeper understanding of the molecular signaling and structural components involved will enable rational design of therapeutic strategies in a wide variety of diseases.
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Affiliation(s)
- E J Pettit
- Biomedical Imaging Group, University of Massachusetts Medical Center, Worcester, USA
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