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Updated: Aug 9, 2026
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A TIRF Microscopy Technique for Real-time, Simultaneous Imaging of the TCR and its Associated Signaling Proteins
Published on: March 22, 2012
Beta 1-integrin-mediated cell signaling in T lymphocytes
S Iwata1, Y Ohashi, K Kamiguchi
1Division of Tumor Immunology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA.
Journal of Dermatological Science
|May 16, 2000
Summary
Crk-associated substrate-related protein L (Cas-L) is vital for beta1-integrin signaling in lymphocytes. Cas-L phosphorylation by focal adhesion kinase (FAK) is essential for beta1-integrin-mediated T-cell co-stimulation.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Beta1-integrins are critical for lymphocyte functions including adhesion, migration, proliferation, and differentiation.
- Understanding beta1-integrin signaling pathways is key to elucidating these cellular processes.
- Previous studies identified several tyrosine-phosphorylated proteins upon beta1-integrin engagement, including pp105.
Purpose of the Study:
- To identify and characterize the role of the beta1-integrin signaling pathway in lymphocytes.
- To investigate the function of pp105, a Cas homologue, designated as Cas-L (Crk-associated substrate-related protein L).
- To elucidate the specific role of Cas-L in beta1-integrin-mediated T-cell co-stimulation.
Main Methods:
- Cloning of Cas-L cDNA and characterization of its structure and binding motifs.
- Analysis of tyrosine phosphorylation of signaling molecules upon beta1-integrin and T-cell receptor (TCR)/CD3 engagement.
- Investigation of protein-protein interactions using wild-type and mutant Cas-L (Cas-LDeltaSH3).
- Functional assays using Jurkat T-cell lines with altered Cas-L expression levels to assess T-cell co-stimulation.
Main Results:
- Cas-L was identified as a Cas homologue predominantly expressed in lymphoid cells, containing SH3 and SH2 binding motifs.
- pp125FAK binds to Cas-L's SH3 domain and phosphorylates its tyrosine residues upon beta1-integrin stimulation.
- Cas-L is involved in both beta1-integrin and TCR/CD3 signaling pathways; FAK is crucial for beta1-integrin but not CD3-dependent phosphorylation.
- Reduced Cas-L expression in Jurkat cells impaired beta1-integrin-mediated T-cell co-stimulation, which was restored by Cas-L transfection.
Conclusions:
- Cas-L plays a critical role in beta1-integrin-mediated T-cell co-stimulation, acting as a docking protein.
- The interaction and phosphorylation of Cas-L by FAK are essential for beta1-integrin signaling in T-cells.
- Cas-L integrates signals from both beta1-integrins and TCR/CD3, influencing various T-cell functions.
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