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Actin foci facilitate activation of the phospholipase C-γ in primary T lymphocytes via the WASP pathway.

Kumari S, Depoil D, Martinelli R, Judokusumo E, Carmona G, Gertler FB, Kam LC, Carman CV, Burkhardt JK, Irvine DJ, Dustin ML - Elife (2015)

Bottom Line: Yet, when WASP function is eliminated there is negligible effect on actin polymerization at the immunological synapse, leading to gaps in our understanding of the events connecting WASP and calcium ion signaling.These foci are polymerized de novo as a result of the T cell receptor (TCR) proximal tyrosine kinase cascade, and facilitate distal signaling events including PLCγ1 activation and subsequent cytoplasmic calcium ion elevation.We conclude that WASP generates a dynamic F-actin architecture in the context of the immunological synapse, which then amplifies the downstream signals required for an optimal immune response.

View Article: PubMed Central - PubMed

Affiliation: Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, United States.

ABSTRACT
Wiscott Aldrich Syndrome protein (WASP) deficiency results in defects in calcium ion signaling, cytoskeletal regulation, gene transcription and overall T cell activation. The activation of WASP constitutes a key pathway for actin filament nucleation. Yet, when WASP function is eliminated there is negligible effect on actin polymerization at the immunological synapse, leading to gaps in our understanding of the events connecting WASP and calcium ion signaling. Here, we identify a fraction of total synaptic F-actin selectively generated by WASP in the form of distinct F-actin 'foci'. These foci are polymerized de novo as a result of the T cell receptor (TCR) proximal tyrosine kinase cascade, and facilitate distal signaling events including PLCγ1 activation and subsequent cytoplasmic calcium ion elevation. We conclude that WASP generates a dynamic F-actin architecture in the context of the immunological synapse, which then amplifies the downstream signals required for an optimal immune response.

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Test of rank-filter based processing method for foci detection.T cells purified from WT or Was−/− mice were incubated with anti-CD3/ICAM1 reconstituted lipid bilayers for 2 min and then stained with Alexa488-phalloidin. WT and WASP−/− cells have comparable levels of total F-actin at synapse (raw images in left panels), as shown in Figure 1. However, WASP−/− cells visibly lack F-actin foci. When processed using local background correction method, the processed images indeed show quantifiably different numbers of foci.DOI:http://dx.doi.org/10.7554/eLife.04953.005
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fig1s2: Test of rank-filter based processing method for foci detection.T cells purified from WT or Was−/− mice were incubated with anti-CD3/ICAM1 reconstituted lipid bilayers for 2 min and then stained with Alexa488-phalloidin. WT and WASP−/− cells have comparable levels of total F-actin at synapse (raw images in left panels), as shown in Figure 1. However, WASP−/− cells visibly lack F-actin foci. When processed using local background correction method, the processed images indeed show quantifiably different numbers of foci.DOI:http://dx.doi.org/10.7554/eLife.04953.005


Actin foci facilitate activation of the phospholipase C-γ in primary T lymphocytes via the WASP pathway.

Kumari S, Depoil D, Martinelli R, Judokusumo E, Carmona G, Gertler FB, Kam LC, Carman CV, Burkhardt JK, Irvine DJ, Dustin ML - Elife (2015)

Test of rank-filter based processing method for foci detection.T cells purified from WT or Was−/− mice were incubated with anti-CD3/ICAM1 reconstituted lipid bilayers for 2 min and then stained with Alexa488-phalloidin. WT and WASP−/− cells have comparable levels of total F-actin at synapse (raw images in left panels), as shown in Figure 1. However, WASP−/− cells visibly lack F-actin foci. When processed using local background correction method, the processed images indeed show quantifiably different numbers of foci.DOI:http://dx.doi.org/10.7554/eLife.04953.005
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4355629&req=5

fig1s2: Test of rank-filter based processing method for foci detection.T cells purified from WT or Was−/− mice were incubated with anti-CD3/ICAM1 reconstituted lipid bilayers for 2 min and then stained with Alexa488-phalloidin. WT and WASP−/− cells have comparable levels of total F-actin at synapse (raw images in left panels), as shown in Figure 1. However, WASP−/− cells visibly lack F-actin foci. When processed using local background correction method, the processed images indeed show quantifiably different numbers of foci.DOI:http://dx.doi.org/10.7554/eLife.04953.005
Bottom Line: Yet, when WASP function is eliminated there is negligible effect on actin polymerization at the immunological synapse, leading to gaps in our understanding of the events connecting WASP and calcium ion signaling.These foci are polymerized de novo as a result of the T cell receptor (TCR) proximal tyrosine kinase cascade, and facilitate distal signaling events including PLCγ1 activation and subsequent cytoplasmic calcium ion elevation.We conclude that WASP generates a dynamic F-actin architecture in the context of the immunological synapse, which then amplifies the downstream signals required for an optimal immune response.

View Article: PubMed Central - PubMed

Affiliation: Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, United States.

ABSTRACT
Wiscott Aldrich Syndrome protein (WASP) deficiency results in defects in calcium ion signaling, cytoskeletal regulation, gene transcription and overall T cell activation. The activation of WASP constitutes a key pathway for actin filament nucleation. Yet, when WASP function is eliminated there is negligible effect on actin polymerization at the immunological synapse, leading to gaps in our understanding of the events connecting WASP and calcium ion signaling. Here, we identify a fraction of total synaptic F-actin selectively generated by WASP in the form of distinct F-actin 'foci'. These foci are polymerized de novo as a result of the T cell receptor (TCR) proximal tyrosine kinase cascade, and facilitate distal signaling events including PLCγ1 activation and subsequent cytoplasmic calcium ion elevation. We conclude that WASP generates a dynamic F-actin architecture in the context of the immunological synapse, which then amplifies the downstream signals required for an optimal immune response.

Show MeSH
Related in: MedlinePlus