liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Towards a Refined Model of Neutrophil Motility
Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
2001 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The ability of human polymorphonuclear leukocytes (PMNL; neutrophils), to sense and move to sites of infection is essential for our defense against pathogens. Cell motility is critically dependent on a dynamic remodeling of morphology. The morphological polarization toward chemoattractants, such as N-formyl-Met-Leu-Phe (fMLF), is associated with temporary extension and stabilization of lamellipodia in the direction of movement. The underlying mechanisms of cell motility are, however, still not entirely elucidated. It is therefore an urgent task to extend the present experimental evidence to give solid basis for a comprehensive model. Here it is shown that nitric oxide (NO) stimulates the morphological response of neutrophils, most likely due to transient increases in [Ca2+]i, following addition of NO-donors. This will, hypothetically, activate gelsolin and other actin filament severing proteins, leading to a subsequent decrease in filamentous actin. The incapability to efficiently turnover the actin filament network then blocks all motile activity. It is also shown that N-formyl peptide receptors on polarized neutrophils accumulate non-uniformly towards regions involved in motility. It is suggested that neutrophils use the asymmetric receptor distribution for directional sensing and sustained migration. A model for lamellipodium extension, where water fluxes play a pivotal role is presented. It is suggested that water fluxes through water-selective aquaporin (AQP) channels, contribute to the propulsive force for formation of various membrane protrusions and, thus, cell motility. It is well known that small G proteins of the Rho family GTPases play important roles in the intracellular signaling underlying cell motility. In morphologically polarized neutrophils it is shown that Cdc42, Rac2 and RhoA display spatially distinct distributions, which allows for sequential chemoattractant stimulation of neutrophil motility. The specific localizations of Rac2, Cdc42 and RhoA relative to each other and filamentous actin and fMLF receptors support the hypothesized order of activation and regulation of neutrophil cell motility. In conclusion, the detailed analysis of motility-related issues presented here provide new data allowing further refinement of previous models of neutrophil motility.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2001. , 135 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 670
Keyword [en]
human polymorphonuclear leukocytes. PMNL, neutrophils, neutrophil motility, N-formyl-Met-Leu-Phe
National Category
Microbiology in the medical area
Identifiers
URN: urn:nbn:se:liu:diva-5142ISBN: 91-7219-964-4 (print)OAI: oai:DiVA.org:liu-5142DiVA: diva2:21048
Public defence
2001-05-04, Aulan, Adm. byggnad, ingång 16, Campus US, Linköpings universitet, Linköping, 13:00 (English)
Opponent
Supervisors
Available from: 2001-05-25 Created: 2001-05-25 Last updated: 2012-01-24Bibliographically approved
List of papers
1. Nitric oxide induces dose-dependent CA2+ transients and causes temporal morphological hyperpolarization in human neutrophils
Open this publication in new window or tab >>Nitric oxide induces dose-dependent CA2+ transients and causes temporal morphological hyperpolarization in human neutrophils
2000 (English)In: Journal of cellular physiology, ISSN 0021-9541, Vol. 182, no 3, 402-413 p.Article in journal (Refereed) Published
Abstract [en]

We exposed adherent neutrophils to the nitric oxide (NO)-radical donors S-nitroso-N-acetylpenicillamine (SNAP), S-nitrosoglutathione (GSNO), and sodium nitroprusside (SNP) to study the role of NO in morphology and Ca(2+) signaling. Parallel to video imaging of cell morphology and migration in neutrophils, changes in intracellular free Ca(2+) ([Ca(2+)](i)) were assessed by ratio imaging of Fura-2. NO induced a rapid and persistent morphological hyperpolarization followed by migrational arrest that usually lasted throughout the 10-min experiments. Addition of 0.5-800 microM SNAP caused concentration-dependent elevation of [Ca(2+)](i) with an optimal effect at 50 microM. This was probably induced by NO itself, because no change in [Ca(2+)](i) was observed after treatment with NO donor byproducts, i.e. D-penicillamine, glutathione, or potassium cyanide. Increasing doses of SNAP (>/=200 microM) attenuated the Ca(2+) response to the soluble chemotactic stimulus formyl-methionyl-leucyl-phenylalanine (fMLP), and both NO- and fMLP-induced Ca(2+) transients were abolished at 800 microM SNAP or more. In kinetic studies of fluorescently labeled actin cytoskeleton, NO markedly reduced the F-actin content and profoundly increased cell area. Immunoblotting to investigate the formation of nitrotyrosine residues in cells exposed to NO donors did not imply nitrosylation, nor could we mimic the effects of NO with the cell permeant form of cGMP, i.e., 8-Br-cGMP. Hence these processes were probably not the principal NO targets. In summary, NO donors initially increased neutrophil morphological alterations, presumably due to an increase in [Ca(2+)](i), and thereafter inhibited such shape changes. Our observations demonstrate that the effects of NO donors are important for regulation of cellular signaling, i.e., Ca(2+) homeostasis, and also affect cell migration, e.g., through effects on F-actin turnover. Our results are discussed in relation to the complex mechanisms that govern basic cell shape changes, required for migration.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13604 (URN)10.1002/(SICI)1097-4652(200003)182:3<402::AID-JCP11>3.0.CO;2-D (DOI)
Available from: 2001-05-25 Created: 2001-05-25 Last updated: 2015-09-18
2. Assessment of neutrophil N-formyl peptide receptors by using antibodies and fluorescent peptides
Open this publication in new window or tab >>Assessment of neutrophil N-formyl peptide receptors by using antibodies and fluorescent peptides
2001 (English)In: Journal of Leukocyte biology, ISSN 0741-5400, Vol. 69, no 5, 762-771 p.Article in journal (Refereed) Published
Abstract [en]

Enrichment of chemoattractant receptors on the neutrophil surface has been difficult to assess, primarily because of limitations in sensitivity of visualization. Using an ultrasensitive, cooled charge-coupled device camera, we investigated spatial-temporal relationships between N-formyl peptide receptor distribution and directional motility of human neutrophils. Live cells were labeled with fluorescent receptor ligands, i.e., fluoresceinated tert-butyl-oxycarbonyl-Phe-(D)-Leu-Phe-(D)-Leu-Phe-OH (Boc-FLFLF) and formyl-Nle-Leu-Phe-Nle-Tyr-Lys (fnLLFnLYK), while fixed cells were labeled with either fluorescent peptides or monoclonal antibodies. Double labeling of receptors and filamentous actin (F-actin) was done to investigate possible colocalization. N-Formyl peptide receptors on unstimulated cells were randomly distributed. However, on polarized neutrophils, the receptors accumulated toward regions involved in motility and distributed nonuniformly. In fixed neutrophils, antibody-labeled receptors colocalized with the F-actin-rich leading edge whereas peptide-labeled receptors lagged behind this region. We suggest that neutrophils use an asymmetric receptor distribution for directional sensing and sustained migration. A separation between receptors labeled with peptides and those labeled with antibodies reflects two functionally distinct receptor populations at the membrane of motile neutrophils.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13605 (URN)
Available from: 2001-05-25 Created: 2001-05-25
3. Neutrophil leukocyte motility requires directed water influx
Open this publication in new window or tab >>Neutrophil leukocyte motility requires directed water influx
Show others...
2002 (English)In: Journal of Leukocyte Biology, ISSN 0741-5400, E-ISSN 1938-3673, Vol. 71, no 2, 212-222 p.Article in journal (Refereed) Published
Abstract [en]

The ability of neutrophils to sense and move to sites of infection is essential for our defense against pathogens. For motility, lamellipodium extension and stabilization are prerequisites, but how cells form such membrane protrusions is still obscure. Using contrast-enhanced video microscopy and Transwell® assays, we show that water-selective aquaporin channels regulate lamellipodium formation and neutrophil motility. Addition of anti-aquaporin-9 antibodies, HgCl2, or tetraethyl ammonium inhibited the function(s) of the channels and blocked motility-related shape changes. On human neutrophils, aquaporin-9 preferentially localized to the cell edges, where N-formyl peptide receptors also accumulated, as assessed with fluorescence microscopy. To directly visualize water fluxes at cell edges, cells were loaded with high dilution-sensitive, self-quenching concentrations of fluorophore. In these cells, motile regions always displayed increased fluorescence compared with perinuclear regions. Our observations provide the first experimental support for motility models where water fluxes play a pivotal role in cell-volume increases accompanying membrane extensions.

Keyword
aquaporins, anti-aquaporin antibodies, microscopy, HgCl2
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13606 (URN)
Available from: 2001-05-25 Created: 2001-05-25 Last updated: 2017-12-13
4. The spatial distribution of RhoA, Rac2 and Cdc42 in human neutrophils allows for sequential chemoattractant stimulation
Open this publication in new window or tab >>The spatial distribution of RhoA, Rac2 and Cdc42 in human neutrophils allows for sequential chemoattractant stimulation
2001 (English)In: FEBS Letters, ISSN 0014-5793Article in journal (Refereed) Submitted
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13607 (URN)
Available from: 2001-05-25 Created: 2001-05-25 Last updated: 2009-04-14

Open Access in DiVA

fulltext(1782 kB)2845 downloads
File information
File name FULLTEXT01.pdfFile size 1782 kBChecksum MD5
aa0a037962e057c27d482ecf9f05d7f91bbd93bf4d193c3cf7b932121780a657b20d01f9
Type fulltextMimetype application/pdf

Authority records BETA

Loitto, Vesa-Matti

Search in DiVA

By author/editor
Loitto, Vesa-Matti
By organisation
Medical MicrobiologyFaculty of Health Sciences
Microbiology in the medical area

Search outside of DiVA

GoogleGoogle Scholar
Total: 2845 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 512 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf