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Updated: Sep 23, 2025

In Vitro Polymerization of F-actin on Early Endosomes
Published on: August 28, 2017
Filamin FLN-2 promotes MVB biogenesis by mediating vesicle docking on the actin cytoskeleton
Leiling Shi1,2,3, Youli Jian1, Meijiao Li4
1National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
Abstract:
Multivesicular bodies (MVBs) contain intralumenal vesicles that are delivered to lysosomes for degradation or released extracellularly for intercellular signaling. Here, we identified Caenorhabditis elegans filamin FLN-2 as a novel regulator of MVB biogenesis. FLN-2 co-localizes with V-ATPase subunits on MVBs, and the loss of FLN-2 affects MVB biogenesis, reducing the number of MVBs in C. elegans hypodermis. FLN-2 associates with actin filaments and is required for F-actin organization. Like fln-2(lf) mutation, inactivation of the V0 or V1 sector of V-ATPase or inhibition of actin polymerization impairs MVB biogenesis. Super-resolution imaging shows that FLN-2 docks V-ATPase-decorated MVBs onto actin filaments. FLN-2 interacts via its calponin-homology domains with F-actin and the V1-E subunit, VHA-8. Our data suggest that FLN-2 mediates the docking of MVBs on the actin cytoskeleton, which is required for MVB biogenesis.
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