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APO-1(CD95)-mediated apoptosis in Jurkat cells does not involve src kinases or CD45
1Division of Applied Immunology, German Cancer Research Center, Heidelberg.
FEBS Letters
|July 24, 1995
Summary
APO-1/Fas signaling in lymphocytes does not require tyrosine phosphorylation mediated by src kinases or CD45. This study found that mutant cells deficient in these proteins still underwent apoptosis upon APO-1 triggering.
Area of Science:
- Immunology
- Cell Signaling
- Molecular Biology
Background:
- Tyrosine phosphorylation is considered an early event in APO-1/Fas (CD95) signaling in lymphocytes.
- The role of specific signaling molecules like src kinases and CD45 in this pathway requires further elucidation.
Purpose of the Study:
- To investigate the necessity of tyrosine phosphorylation, src kinases, and CD45 in APO-1/Fas-mediated apoptosis.
- To compare the apoptotic response of wild-type Jurkat cells with mutant cell lines deficient in CD45 or p56lck.
Main Methods:
- Utilized Jurkat cell lines with deficiencies in CD45 (J45.01) and p56lck (JCaM1.6), alongside wild-type Jurkat cells.
- Triggered APO-1-induced apoptosis and assessed tyrosine phosphorylation levels in cytosolic proteins.
- Administered herbimycin A to evaluate its effect on apoptosis and src-related kinase activity.
Main Results:
- No significant difference in APO-1-induced apoptosis was observed between wild-type and mutant Jurkat cell lines.
- APO-1 triggering in mutant cells did not lead to increased tyrosine phosphorylation of cytosolic proteins.
- Herbimycin A augmented apoptosis rather than inhibiting it, despite degrading src-related kinases lck and fyn.
Conclusions:
- APO-1-mediated signaling and subsequent apoptosis are independent of src kinases and CD45.
- Tyrosine phosphorylation events involving src kinases and CD45 are not essential for APO-1/Fas-induced lymphocyte apoptosis.