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Membrane expansion increases endocytosis rate during mitosis.

Raucher D, Sheetz MP - J. Cell Biol. (1999)

Bottom Line: Mitosis in mammalian cells is accompanied by a dramatic inhibition of endocytosis.We have found that the addition of amphyphilic compounds to metaphase cells increases the endocytosis rate even to interphase levels.Detergents and solvents all increased endocytosis rate, and the extent of increase was in direct proportion to the concentration added.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.

ABSTRACT
Mitosis in mammalian cells is accompanied by a dramatic inhibition of endocytosis. We have found that the addition of amphyphilic compounds to metaphase cells increases the endocytosis rate even to interphase levels. Detergents and solvents all increased endocytosis rate, and the extent of increase was in direct proportion to the concentration added. Although the compounds could produce a variety of different effects, we have found a strong correlation with a physical alteration in the membrane tension as measured by the laser tweezers. Plasma membrane tethers formed by latex beads pull back on the beads with a force that was related to the in-plane bilayer tension and membrane- cytoskeletal adhesion. We found that as cells enter mitosis, the membrane tension rises as the endocytosis rate decreases; and as cells exited mitosis, the endocytosis rate increased as the membrane tension decreased. The addition of amphyphilic compounds decreased membrane tension and increased the endocytosis rate. With the detergent, deoxycholate, the endocytosis rate was restored to interphase levels when the membrane tension was restored to interphase levels. Although biochemical factors are clearly involved in the alterations in mitosis, we suggest that endocytosis is blocked primarily by the increase in apparent plasma membrane tension. Higher tensions inhibit both the binding of the endocytic complex to the membrane and mechanical deformation of the membrane during invagination. We suggest that membrane tension is an important regulator of the endocytosis rate and alteration of tension is sufficient to modify endocytosis rates during mitosis. Further, we postulate that the rise in membrane tension causes cell rounding and the inhibition of motility, characteristic of mitosis.

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Titration of membrane tension with increasing concentrations of deoxycholic acid. (a) Nonsynchronized HeLa cells  plated on a glass coverslips were incubated for 10 min in various  concentrations of deoxycholic acid and the tether force measured  as described in Fig. 3. Error bars represents SEM for 10–25 measurements.
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Figure 6: Titration of membrane tension with increasing concentrations of deoxycholic acid. (a) Nonsynchronized HeLa cells plated on a glass coverslips were incubated for 10 min in various concentrations of deoxycholic acid and the tether force measured as described in Fig. 3. Error bars represents SEM for 10–25 measurements.

Mentions: If there is an inverse dependence of endocytosis rate on membrane tension, then the endocytosis rate of metaphase cells should continuously increase to interphase levels as the membrane tension is decreased to interphase levels. To test this, we measured tether force and endocytosis rate immediately after the addition of increasing amounts of deoxycholic acid (Fig. 6). Increasing deoxycholic acid concentrations caused a linear decrease in tether force in interphase and metaphase cells (Fig. 6). In 0.4 mM deoxycholic acid, the tether force in interphase cells and metaphase cells decreased by 45 and 65%, respectively compared with control cells. The metaphase cells were more sensitive to detergent concentration than interphase cells. At 0.4 mM deoxycholic acid, tether force in metaphase cells corresponded to tether force in untreated interphase cells. Uptake of endocytic vesicles in interphase and metaphase cells increases in parallel with the increase in concentration of deoxycholic acid (Fig. 2). Moreover, treatment of the cells with 0.4 mM deoxycholic acid increased endocytosis rate of metaphase cells to the value that matches the rate of untreated interphase cells. The return to interphase endocytosis rates was confirmed by measuring endocytosis of fluorescein dextran. Upon addition of 0.4 mM deoxycholic acid, metaphase cells increased their uptake of fluorescein dextran to 93 ± 7% (STD, n = 11) of untreated interphase cells. Results obtained by both methods and fluorescent dyes indicated that when membrane tension in metaphase cells is adjusted to the interphase level with detergent addition, the endocytosis rate reaches the interphase level. This treatment did not obviously alter the mitotic process, since cells in mitosis completed cytokinesis in the presence of 0.4 mM deoxycholic acid.


Membrane expansion increases endocytosis rate during mitosis.

Raucher D, Sheetz MP - J. Cell Biol. (1999)

Titration of membrane tension with increasing concentrations of deoxycholic acid. (a) Nonsynchronized HeLa cells  plated on a glass coverslips were incubated for 10 min in various  concentrations of deoxycholic acid and the tether force measured  as described in Fig. 3. Error bars represents SEM for 10–25 measurements.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2132908&req=5

Figure 6: Titration of membrane tension with increasing concentrations of deoxycholic acid. (a) Nonsynchronized HeLa cells plated on a glass coverslips were incubated for 10 min in various concentrations of deoxycholic acid and the tether force measured as described in Fig. 3. Error bars represents SEM for 10–25 measurements.
Mentions: If there is an inverse dependence of endocytosis rate on membrane tension, then the endocytosis rate of metaphase cells should continuously increase to interphase levels as the membrane tension is decreased to interphase levels. To test this, we measured tether force and endocytosis rate immediately after the addition of increasing amounts of deoxycholic acid (Fig. 6). Increasing deoxycholic acid concentrations caused a linear decrease in tether force in interphase and metaphase cells (Fig. 6). In 0.4 mM deoxycholic acid, the tether force in interphase cells and metaphase cells decreased by 45 and 65%, respectively compared with control cells. The metaphase cells were more sensitive to detergent concentration than interphase cells. At 0.4 mM deoxycholic acid, tether force in metaphase cells corresponded to tether force in untreated interphase cells. Uptake of endocytic vesicles in interphase and metaphase cells increases in parallel with the increase in concentration of deoxycholic acid (Fig. 2). Moreover, treatment of the cells with 0.4 mM deoxycholic acid increased endocytosis rate of metaphase cells to the value that matches the rate of untreated interphase cells. The return to interphase endocytosis rates was confirmed by measuring endocytosis of fluorescein dextran. Upon addition of 0.4 mM deoxycholic acid, metaphase cells increased their uptake of fluorescein dextran to 93 ± 7% (STD, n = 11) of untreated interphase cells. Results obtained by both methods and fluorescent dyes indicated that when membrane tension in metaphase cells is adjusted to the interphase level with detergent addition, the endocytosis rate reaches the interphase level. This treatment did not obviously alter the mitotic process, since cells in mitosis completed cytokinesis in the presence of 0.4 mM deoxycholic acid.

Bottom Line: Mitosis in mammalian cells is accompanied by a dramatic inhibition of endocytosis.We have found that the addition of amphyphilic compounds to metaphase cells increases the endocytosis rate even to interphase levels.Detergents and solvents all increased endocytosis rate, and the extent of increase was in direct proportion to the concentration added.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.

ABSTRACT
Mitosis in mammalian cells is accompanied by a dramatic inhibition of endocytosis. We have found that the addition of amphyphilic compounds to metaphase cells increases the endocytosis rate even to interphase levels. Detergents and solvents all increased endocytosis rate, and the extent of increase was in direct proportion to the concentration added. Although the compounds could produce a variety of different effects, we have found a strong correlation with a physical alteration in the membrane tension as measured by the laser tweezers. Plasma membrane tethers formed by latex beads pull back on the beads with a force that was related to the in-plane bilayer tension and membrane- cytoskeletal adhesion. We found that as cells enter mitosis, the membrane tension rises as the endocytosis rate decreases; and as cells exited mitosis, the endocytosis rate increased as the membrane tension decreased. The addition of amphyphilic compounds decreased membrane tension and increased the endocytosis rate. With the detergent, deoxycholate, the endocytosis rate was restored to interphase levels when the membrane tension was restored to interphase levels. Although biochemical factors are clearly involved in the alterations in mitosis, we suggest that endocytosis is blocked primarily by the increase in apparent plasma membrane tension. Higher tensions inhibit both the binding of the endocytic complex to the membrane and mechanical deformation of the membrane during invagination. We suggest that membrane tension is an important regulator of the endocytosis rate and alteration of tension is sufficient to modify endocytosis rates during mitosis. Further, we postulate that the rise in membrane tension causes cell rounding and the inhibition of motility, characteristic of mitosis.

Show MeSH
Related in: MedlinePlus