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Updated: Dec 25, 2025
Visualizing the Actin and Microtubule Cytoskeletons at the B-cell Immune Synapse Using Stimulated Emission Depletion STED Microscopy
Published on: April 9, 2018
CD20 is dispensable for B-cell receptor signaling but is required for proper actin polymerization, adhesion and
Veronika Kozlova1,2, Aneta Ledererova1,2, Adriana Ladungova1
1Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic.
Abstract:
Surface protein CD20 serves as the critical target of immunotherapy in various B-cell malignancies for decades, however its biological function and regulation remain largely elusive. Better understanding of CD20 function may help to design improved rational therapies to prevent development of resistance. Using CRISPR/Cas9 technique, we have abrogated CD20 expression in five different malignant B-cell lines. We show that CD20 deletion has no effect upon B-cell receptor signaling or calcium flux. Also B-cell survival and proliferation is unaffected in the absence of CD20. On the contrary, we found a strong defect in actin cytoskeleton polymerization and, consequently, defective cell adhesion and migration in response to homeostatic chemokines SDF1α, CCL19 and CCL21. Mechanistically, we could identify a reduction in chemokine-triggered PYK2 activation, a calcium-activated signaling protein involved in activation of MAP kinases and cytoskeleton regulation. These cellular defects in consequence result in a severely disturbed homing of B cells in vivo.
Insights
Surface protein CD20 is crucial for B-cell malignancies immunotherapy. Its absence impairs B-cell migration and homing by affecting actin cytoskeleton polymerization and PYK2 activation, not B-cell signaling or survival.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Surface protein CD20 is a key target in B-cell malignancy immunotherapies.
- The precise biological functions and regulatory mechanisms of CD20 are not fully understood.
- Elucidating CD20's role may lead to improved therapies and resistance prevention.
Purpose of the Study:
- To investigate the functional role of CD20 in malignant B-cells.
- To understand how CD20 expression influences B-cell signaling, survival, proliferation, and migration.
- To identify the molecular mechanisms underlying CD20's cellular functions.
Main Methods:
- CRISPR/Cas9 gene editing was employed to abrogate CD20 expression in five malignant B-cell lines.
- B-cell receptor signaling, calcium flux, survival, and proliferation were assessed.
- Actin cytoskeleton polymerization, cell adhesion, and migration in response to chemokines (SDF1α, CCL19, CCL21) were analyzed.
- Chemokine-triggered PYK2 activation was investigated as a potential mechanism.
Main Results:
- CD20 deletion did not impact B-cell receptor signaling, calcium flux, survival, or proliferation.
- A significant defect in actin cytoskeleton polymerization was observed in CD20-deficient cells.
- Defective cell adhesion and migration towards homeostatic chemokines were noted.
- Reduced chemokine-induced PYK2 activation was identified as a key mechanistic finding.
Conclusions:
- CD20 is essential for normal B-cell migration and homing, independent of its role in B-cell receptor signaling or survival.
- CD20 regulates actin cytoskeleton dynamics and cell migration via modulation of PYK2 activation.
- These findings reveal novel functions of CD20 beyond its immunotherapeutic target status and have implications for B-cell malignancy treatment.
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