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Updated: Nov 4, 2025

Visualizing the Actin and Microtubule Cytoskeletons at the B-cell Immune Synapse Using Stimulated Emission Depletion STED Microscopy
Published on: April 9, 2018
Ecm29-Dependent Proteasome Localization Regulates Cytoskeleton Remodeling at the Immune Synapse
Jorge Ibañez-Vega1, Felipe Del Valle1, Juan José Sáez1
1Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
B cells use proteasomes to control actin dynamics at the immune synapse (IS). Ecm29 protein regulates proteasome distribution, impacting antigen capture and cell spreading.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Immune synapse (IS) formation in B cells involves actin cytoskeleton remodeling for antigen capture.
- Lysosome recruitment to the IS facilitates antigen extraction, but actin regulation remains unclear.
Purpose of the Study:
- To investigate how B cells regulate actin dynamics at the centrosome and IS.
- To elucidate the role of Ecm29 in proteasome distribution and its impact on B cell function.
Main Methods:
- Studied proteasome distribution in B cells using Ecm29 silencing.
- Analyzed actin dynamics, centrosome and lysosome positioning, and antigen presentation in Ecm29-silenced B cells.
Main Results:
- Ecm29 silencing decreased centrosomal proteasomes, increasing F-actin at the centrosome.
- Impaired lysosome repositioning and antigen extraction were observed in Ecm29-silenced cells.
- Ecm29-silenced cells showed enhanced spreading due to altered actin retrograde flow.
Conclusions:
- Ecm29 mediates asymmetric proteasome distribution, coordinating actin dynamics at the centrosome and IS.
- This coordination is crucial for lysosome recruitment, antigen extraction, and B cell spreading.
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