Affiliation:
1. MRC Laboratory of Molecular Biology Cambridge UK
2. Department of Biology and Integrative Program for Biological and Genome Sciences The University of North Carolina at Chapel Hill Chapel Hill NC USA
Abstract
AbstractCytoplasmic microtubules are tubular polymers that can harbor small proteins or filaments inside their lumen. The identities of these objects and mechanisms for their accumulation have not been conclusively established. Here, we used cryogenic electron tomography of Drosophila S2 cell protrusions and found filaments inside the microtubule lumen, which resemble those reported recently in human HAP1 cells. The frequency of these filaments increased upon inhibition of the sarco/endoplasmic reticulum Ca2+ ATPase with the small molecule drug thapsigargin. Subtomogram averaging showed that the luminal filaments adopt a helical structure reminiscent of cofilin‐bound actin (cofilactin). Consistent with this, we observed cofilin dephosphorylation, an activating modification, in cells under the same conditions that increased luminal filament occurrence. Furthermore, RNA interference knock‐down of cofilin reduced the frequency of luminal filaments with cofilactin morphology. These results suggest that cofilin activation stimulates its accumulation on actin filaments inside the microtubule lumen.
Funder
Cambridge Commonwealth, European and International Trust
National Institute of Neurological Disorders and Stroke
Wellcome Trust
Publisher
Springer Science and Business Media LLC
Subject
Genetics,Molecular Biology,Biochemistry
Cited by
2 articles.
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