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An unmet actin requirement explains the mitotic inhibition of clathrin-mediated endocytosis.

Kaur S, Fielding AB, Gassner G, Carter NJ, Royle SJ - Elife (2014)

Bottom Line: In this study, we show that the mitotic shutdown is due to an unmet requirement for actin in CME.However, the actin cytoskeleton is engaged in the formation of a rigid cortex in mitotic cells and is therefore unavailable for deployment.Mitotic phosphorylation of endocytic proteins is maintained in mitotic cells with restored CME, indicating that direct phosphorylation of the CME machinery does not account for shutdown.

View Article: PubMed Central - PubMed

Affiliation: Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Coventry, United Kingdom.

ABSTRACT
Clathrin-mediated endocytosis (CME) is the major internalisation route for many different receptor types in mammalian cells. CME is shut down during early mitosis, but the mechanism of this inhibition is unclear. In this study, we show that the mitotic shutdown is due to an unmet requirement for actin in CME. In mitotic cells, membrane tension is increased and this invokes a requirement for the actin cytoskeleton to assist the CME machinery to overcome the increased load. However, the actin cytoskeleton is engaged in the formation of a rigid cortex in mitotic cells and is therefore unavailable for deployment. We demonstrate that CME can be 'restarted' in mitotic cells despite high membrane tension, by allowing actin to engage in endocytosis. Mitotic phosphorylation of endocytic proteins is maintained in mitotic cells with restored CME, indicating that direct phosphorylation of the CME machinery does not account for shutdown. DOI: http://dx.doi.org/10.7554/eLife.00829.001.

No MeSH data available.


Related in: MedlinePlus

Osmolarity change and CME.Transferrin uptake in HeLa cells treated as indicated by diluting the media by the indicated amount of water. Geo Mean from a population of >1 x 10^4 cells is shown.
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fig8: Osmolarity change and CME.Transferrin uptake in HeLa cells treated as indicated by diluting the media by the indicated amount of water. Geo Mean from a population of >1 x 10^4 cells is shown.

Mentions: We have carried out a serial dilution toward hypo-osmotic conditions (see Author response image 1 below). This manipulation eventually inhibits CME in interphase cells, but CME in mitotic cells in unaffected. To decrease membrane tension hyper-osmotic conditions are required, to shrink the cell. This condition (e.g., 0.45M sucrose) is known to inhibit CME by making clathrin form microcages. We tried to dial this back using different salt concentrations and got good inhibition in the interphase cells and no increase in mitotic cells.Author response image 1.Osmolarity change and CME.


An unmet actin requirement explains the mitotic inhibition of clathrin-mediated endocytosis.

Kaur S, Fielding AB, Gassner G, Carter NJ, Royle SJ - Elife (2014)

Osmolarity change and CME.Transferrin uptake in HeLa cells treated as indicated by diluting the media by the indicated amount of water. Geo Mean from a population of >1 x 10^4 cells is shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3924242&req=5

fig8: Osmolarity change and CME.Transferrin uptake in HeLa cells treated as indicated by diluting the media by the indicated amount of water. Geo Mean from a population of >1 x 10^4 cells is shown.
Mentions: We have carried out a serial dilution toward hypo-osmotic conditions (see Author response image 1 below). This manipulation eventually inhibits CME in interphase cells, but CME in mitotic cells in unaffected. To decrease membrane tension hyper-osmotic conditions are required, to shrink the cell. This condition (e.g., 0.45M sucrose) is known to inhibit CME by making clathrin form microcages. We tried to dial this back using different salt concentrations and got good inhibition in the interphase cells and no increase in mitotic cells.Author response image 1.Osmolarity change and CME.

Bottom Line: In this study, we show that the mitotic shutdown is due to an unmet requirement for actin in CME.However, the actin cytoskeleton is engaged in the formation of a rigid cortex in mitotic cells and is therefore unavailable for deployment.Mitotic phosphorylation of endocytic proteins is maintained in mitotic cells with restored CME, indicating that direct phosphorylation of the CME machinery does not account for shutdown.

View Article: PubMed Central - PubMed

Affiliation: Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Coventry, United Kingdom.

ABSTRACT
Clathrin-mediated endocytosis (CME) is the major internalisation route for many different receptor types in mammalian cells. CME is shut down during early mitosis, but the mechanism of this inhibition is unclear. In this study, we show that the mitotic shutdown is due to an unmet requirement for actin in CME. In mitotic cells, membrane tension is increased and this invokes a requirement for the actin cytoskeleton to assist the CME machinery to overcome the increased load. However, the actin cytoskeleton is engaged in the formation of a rigid cortex in mitotic cells and is therefore unavailable for deployment. We demonstrate that CME can be 'restarted' in mitotic cells despite high membrane tension, by allowing actin to engage in endocytosis. Mitotic phosphorylation of endocytic proteins is maintained in mitotic cells with restored CME, indicating that direct phosphorylation of the CME machinery does not account for shutdown. DOI: http://dx.doi.org/10.7554/eLife.00829.001.

No MeSH data available.


Related in: MedlinePlus