Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • 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
Limited cholesterol depletion causes aggregation of plasma membrane lipid raftsinducing T cell activation
Stockholm University, Faculty of Science, The Wenner-Gren Institute .
Stockholm University, Faculty of Science, The Wenner-Gren Institute .
Stockholm University, Faculty of Science, The Wenner-Gren Institute .
Stockholm University, Faculty of Science, The Wenner-Gren Institute .
2010 (English)In: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids, ISSN 1388-1981, E-ISSN 1879-2618, Vol. 1801, no 6, 625-634 p.Article in journal (Refereed) Published
Abstract [en]

Acute cholesterol depletion is generally associated with decreased or abolished T cell signalling but it can also cause T cell activation. This anomaly has been addressed in Jurkat T cells using progressive cholesterol depletion with methyl-beta-cyclodextrin (MBCD). At depletion levels higher than 50% there is substantial cell death, which explains reports of signalling inhibition. At 10–20% depletion levels, tyrosine phosphorylation is increased, ERK is activated and there is a small increase in cytoplasmic Ca2+. Peripheral actin polymerisation is also triggered by limited cholesterol depletion. Strikingly, the lipid raft marker GM1 aggregates upon cholesterol depletion and these aggregated domains concentrate the signalling proteins Lck and LAT, whereas the opposite is true for the non lipid raft marker the transferrin receptor. Using PP2, an inhibitor of Src family kinase activation, it is demonstrated that the lipid raft aggregation occurs independently of and thus upstream of the signalling response. Upon cholesterol depletion there is an increase in overall plasma membrane order, indicative of more ordered domains forming at the expense of disordered domains. That cholesterol depletion and not unspecific effects of MBCD was behind the reported results was confirmed by performing all experiments with MBCD–cholesterol, when no net cholesterol extraction took place. We conclude that non-lethal cholesterol depletion causes the aggregation of lipid rafts which then induces T cell signalling.

Place, publisher, year, edition, pages
2010. Vol. 1801, no 6, 625-634 p.
Keyword [en]
Actin, Cholesterol, Colocalization, Lipid raft, Membrane order, Methyl-beta-cyclodextrin, T cell signalling
National Category
Cell Biology
Research subject
Cell Biology
Identifiers
URN: urn:nbn:se:su:diva-38360DOI: 10.1016/j.bbalip.2010.02.003ISI: 000277912600003OAI: oai:DiVA.org:su-38360DiVA: diva2:309911
Available from: 2010-04-09 Created: 2010-04-09 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Cholesterol in T cells: homeostasis, plasma membrane organization and signaling
Open this publication in new window or tab >>Cholesterol in T cells: homeostasis, plasma membrane organization and signaling
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The plasma membrane of eukaryotic cells contains cholesterol and glycosphingolipids enriched nanodomains known as lipid rafts; which are believed to exist in a liquid ordered (lo) state. Methyl-beta-cyclodextrin (MBCD) is used to deplete cellular cholesterol and a widespread assumption is that MBCD preferentially targets cholesterol in lipid rafts. To analyze this in T cells a progressive cholesterol extraction protocols was established. At 37ºC, MBCD treatment does not lead to the preferential loss of cholesterol from TX-DRMs. At 0ºC only 35% of total cholesterol could be extracted demonstrating that less than 35% of the cell’s cholesterol is found in the plasma membrane. Moreover, incubation of cells at 0ºC causes loss of plasma membrane cholesterol and an increase in cholesteryl esters. The increase in cholesterol esters upon cold exposure is linked to the cholesterol concentration induced activation of ACAT enzyme which converts cholesterol to cholesteryl esters. Cholesterol concentration specific activation of ACAT and conversion of cholesterol to cholesteryl esters during the loading of cholesterol onto T cells by MBCD was also observed. By using MBCD for progressive cholesterol depletion from T cells at 37ºC, the effect of cholesterol depletion on T cell signaling was addressed. At 10-20% cholesterol depletion levels, tyrosine phosphorylation is increased and ERK is activated. Peripheral actin polymerization, cell spreading and membrane protrusions are also triggered by limited cholesterol depletion. Upon limited cholesterol depletion aggregation of lipid rafts in the plasma membrane was observed. The aggregation of lipid rafts upon cholesterol depletion does not dependent on the signaling proteins such as Src-kinases. Upon cholesterol depletion there is an increase in overall plasma membrane order, indicative of more ordered domains forming at the expense of disordered domains.

Place, publisher, year, edition, pages
Stockholm: The Wenner-Gren Institute, Stockholm University, 2010. 76 p.
Keyword
Plasma membrane, T cells, Cholesterol, Lipid rafts, Membrane organization, Cholesterol homeostasis, cholesteryl esters
National Category
Cell Biology
Research subject
Cellbiology
Identifiers
urn:nbn:se:su:diva-38357 (URN)978-91-7447-055-0 (ISBN)
Public defence
2010-05-03, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: In press. Available from: 2010-04-11 Created: 2010-04-09 Last updated: 2010-04-12Bibliographically approved
2. Plasma membrane order; the role of cholesterol and links to actin filaments:  
Open this publication in new window or tab >>Plasma membrane order; the role of cholesterol and links to actin filaments:  
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The connection between T cell activation, plasma membrane order and actin filament dynamics was the main focus of this study. Laurdan and di-4-ANEPPDHQ, membrane order sensing probes, were shown to report only on lipid packing rather than being influenced by the presence of membrane-inserted peptides justifying their use in membrane order studies. These dyes were used to follow plasma membrane order in live cells at 37°C. Disrupting actin filaments had a disordering effect while stabilizing actin filaments had an ordering effect on the plasma membrane, indicating there is a basal level of ordered domains in resting cells. Lowering PI(4,5)P2 levels decreased the proportion of ordered domains strongly suggesting that the connection of actin filaments to the plasma membrane is responsible for the maintaining the level of ordered membrane domains. Membrane blebs, which are detached from the underlying actin filaments, contained a low fraction of ordered domains. Aggregation of membrane components resulted in a higher proportion of ordered plasma membrane domains and an increase in cell peripheral actin polymerization. This strongly suggests that the attachment of actin filaments to the plasma membrane induces the formation of ordered domains. Limited cholesterol depletion with methyl-beta-cyclodextrin triggered peripheral actin polymerization. Cholesterol depleted cells showed an increase in plasma membrane order as a result of actin filament accumulation underneath the membrane. Moderate cholesterol depletion also induced membrane domain aggregation and activation of T cell signaling events. The T cell receptor (TCR) aggregation caused redistribution of domains resulting in TCR patches of higher order and the bulk membrane correspondingly depleted of ordered domains. This suggests the preexistence of small ordered membrane domains in resting T cells that aggregate upon cell activation. Increased actin polymerization at the TCR aggregation sites showed that actin polymerization is strongly correlated with the changes in the distribution of ordered domains. The distribution of the TCR in resting cells and its colocalization with actin filaments is cell cycle dependent. We conclude that actin filament attachment to the plasma membrane, which is regulated via PI(4,5)P2, plays a crucial role in the formation of ordered domains.

Place, publisher, year, edition, pages
Stockholm: The Wenner-Gren Institute, Stockholm University, 2011. 56 p.
Keyword
Membrane Organization, Lipid rafts, Actin, Laurdan, di-4-ANEPPDHQ, Cholesterol, T cell signaling, Colocalization, Generalized Polarization
National Category
Cell Biology
Research subject
Cellbiology
Identifiers
urn:nbn:se:su:diva-62279 (URN)978-91-7447-365-0 (ISBN)
Public defence
2011-10-14, E306, Arrheniuslaboratorierna, Svante Arrhenius väg 20 C, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 4: Manuscript. Available from: 2011-09-22 Created: 2011-09-13 Last updated: 2011-09-16Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Mahammad, SaleemullaDinic, JelenaAdler, JeremyParmryd, Ingela
By organisation
The Wenner-Gren Institute
In the same journal
Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Cell Biology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 46 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • 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