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Dictyostelium dynamin B modulates cytoskeletal structures and membranous organelles.

Rai A, Nöthe H, Tzvetkov N, Korenbaum E, Manstein DJ - Cell. Mol. Life Sci. (2010)

Bottom Line: The mature form of dynamin B mediates a wide range and unique combination of functions.The modulating effect of dynamin B on the activity of the contractile vacuole system is unique for the Dictyostelium system.Other functions displayed by dynamin B are commonly associated with either classical dynamins or dynamin-related proteins.

View Article: PubMed Central - PubMed

Affiliation: Institut für Biophysikalische Chemie, Medizinische Hochschule Hannover, Carl-Neuberg-Straße, Germany.

ABSTRACT
Dictyostelium discoideum cells produce five dynamin family proteins. Here, we show that dynamin B is the only member of this group of proteins that is initially produced as a preprotein and requires processing by mitochondrial proteases for formation of the mature protein. Our results show that dynamin B-depletion affects many aspects of cell motility, cell-cell and cell-surface adhesion, resistance to osmotic shock, and fatty acid metabolism. The mature form of dynamin B mediates a wide range and unique combination of functions. Dynamin B affects events at the plasma membrane, peroxisomes, the contractile vacuole system, components of the actin-based cytoskeleton, and cell adhesion sites. The modulating effect of dynamin B on the activity of the contractile vacuole system is unique for the Dictyostelium system. Other functions displayed by dynamin B are commonly associated with either classical dynamins or dynamin-related proteins.

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Changes in dymB expression affect adhesion. Adhesion levels for wild-type (black bars), dymB− (white bars), and dymB+ cells (grey bars) are shown normalized for control measurements with wild-type cells. a Substrate adhesion of wild-type, dymB−, and dymB+ cells was measured in the absence (total adhesion) and in the presence (cation-dependent adhesion) of EDTA. b Cell-to-cell adhesion is increased in dymB− and decreased in dymB+ cells. Adhesion of AX2 cells was set as 100%. dymB+ represents dymB− cells overproducing dynamin B protein. Error bars represent the standard deviations for five independent measurements. c AX2 and dymB− cells were analyzed by RICM/DIC double-view live-cell confocal microscopy. Dynamin B-depleted cells are flatter than wild-type cells and display an increased contact surface. RICM images are shown in the right panel and the corresponding bright-field images in the left panel. Scale bar 5 μm. d Depletion of dynamin B leads to an increase in the cell-attachment area (N = 132, P value <10−15). The normalized attachment area per cell was calculated as ratio of the contact areas observed in RIC and DIC images
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Fig7: Changes in dymB expression affect adhesion. Adhesion levels for wild-type (black bars), dymB− (white bars), and dymB+ cells (grey bars) are shown normalized for control measurements with wild-type cells. a Substrate adhesion of wild-type, dymB−, and dymB+ cells was measured in the absence (total adhesion) and in the presence (cation-dependent adhesion) of EDTA. b Cell-to-cell adhesion is increased in dymB− and decreased in dymB+ cells. Adhesion of AX2 cells was set as 100%. dymB+ represents dymB− cells overproducing dynamin B protein. Error bars represent the standard deviations for five independent measurements. c AX2 and dymB− cells were analyzed by RICM/DIC double-view live-cell confocal microscopy. Dynamin B-depleted cells are flatter than wild-type cells and display an increased contact surface. RICM images are shown in the right panel and the corresponding bright-field images in the left panel. Scale bar 5 μm. d Depletion of dynamin B leads to an increase in the cell-attachment area (N = 132, P value <10−15). The normalized attachment area per cell was calculated as ratio of the contact areas observed in RIC and DIC images

Mentions: Dynamin B deletion mutants adhere to the surface more than threefold stronger than wild-type cells. It is known that D. discoideum has two types of adhesion sites that differ in their sensitivity to bivalent cations. Contact sites of type A (CsA) are stable in the presence of EDTA concentrations above 10 mM and are produced by the cells during the aggregation stage of development. Contact sites of type B (CsB) appear during early development and are easily disrupted in the presence of 1–2 mM EDTA [55]. In the presence of EDTA dymB− cells displayed only marginally better adhesion, indicating that the observed effect is CsB dependent. Transformation of dymB− cells with an expression vector carrying a functional copy of the dymB gene leads to the complete rescue of the adhesion phenotype (Fig. 7a).Fig. 7


Dictyostelium dynamin B modulates cytoskeletal structures and membranous organelles.

Rai A, Nöthe H, Tzvetkov N, Korenbaum E, Manstein DJ - Cell. Mol. Life Sci. (2010)

Changes in dymB expression affect adhesion. Adhesion levels for wild-type (black bars), dymB− (white bars), and dymB+ cells (grey bars) are shown normalized for control measurements with wild-type cells. a Substrate adhesion of wild-type, dymB−, and dymB+ cells was measured in the absence (total adhesion) and in the presence (cation-dependent adhesion) of EDTA. b Cell-to-cell adhesion is increased in dymB− and decreased in dymB+ cells. Adhesion of AX2 cells was set as 100%. dymB+ represents dymB− cells overproducing dynamin B protein. Error bars represent the standard deviations for five independent measurements. c AX2 and dymB− cells were analyzed by RICM/DIC double-view live-cell confocal microscopy. Dynamin B-depleted cells are flatter than wild-type cells and display an increased contact surface. RICM images are shown in the right panel and the corresponding bright-field images in the left panel. Scale bar 5 μm. d Depletion of dynamin B leads to an increase in the cell-attachment area (N = 132, P value <10−15). The normalized attachment area per cell was calculated as ratio of the contact areas observed in RIC and DIC images
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3142549&req=5

Fig7: Changes in dymB expression affect adhesion. Adhesion levels for wild-type (black bars), dymB− (white bars), and dymB+ cells (grey bars) are shown normalized for control measurements with wild-type cells. a Substrate adhesion of wild-type, dymB−, and dymB+ cells was measured in the absence (total adhesion) and in the presence (cation-dependent adhesion) of EDTA. b Cell-to-cell adhesion is increased in dymB− and decreased in dymB+ cells. Adhesion of AX2 cells was set as 100%. dymB+ represents dymB− cells overproducing dynamin B protein. Error bars represent the standard deviations for five independent measurements. c AX2 and dymB− cells were analyzed by RICM/DIC double-view live-cell confocal microscopy. Dynamin B-depleted cells are flatter than wild-type cells and display an increased contact surface. RICM images are shown in the right panel and the corresponding bright-field images in the left panel. Scale bar 5 μm. d Depletion of dynamin B leads to an increase in the cell-attachment area (N = 132, P value <10−15). The normalized attachment area per cell was calculated as ratio of the contact areas observed in RIC and DIC images
Mentions: Dynamin B deletion mutants adhere to the surface more than threefold stronger than wild-type cells. It is known that D. discoideum has two types of adhesion sites that differ in their sensitivity to bivalent cations. Contact sites of type A (CsA) are stable in the presence of EDTA concentrations above 10 mM and are produced by the cells during the aggregation stage of development. Contact sites of type B (CsB) appear during early development and are easily disrupted in the presence of 1–2 mM EDTA [55]. In the presence of EDTA dymB− cells displayed only marginally better adhesion, indicating that the observed effect is CsB dependent. Transformation of dymB− cells with an expression vector carrying a functional copy of the dymB gene leads to the complete rescue of the adhesion phenotype (Fig. 7a).Fig. 7

Bottom Line: The mature form of dynamin B mediates a wide range and unique combination of functions.The modulating effect of dynamin B on the activity of the contractile vacuole system is unique for the Dictyostelium system.Other functions displayed by dynamin B are commonly associated with either classical dynamins or dynamin-related proteins.

View Article: PubMed Central - PubMed

Affiliation: Institut für Biophysikalische Chemie, Medizinische Hochschule Hannover, Carl-Neuberg-Straße, Germany.

ABSTRACT
Dictyostelium discoideum cells produce five dynamin family proteins. Here, we show that dynamin B is the only member of this group of proteins that is initially produced as a preprotein and requires processing by mitochondrial proteases for formation of the mature protein. Our results show that dynamin B-depletion affects many aspects of cell motility, cell-cell and cell-surface adhesion, resistance to osmotic shock, and fatty acid metabolism. The mature form of dynamin B mediates a wide range and unique combination of functions. Dynamin B affects events at the plasma membrane, peroxisomes, the contractile vacuole system, components of the actin-based cytoskeleton, and cell adhesion sites. The modulating effect of dynamin B on the activity of the contractile vacuole system is unique for the Dictyostelium system. Other functions displayed by dynamin B are commonly associated with either classical dynamins or dynamin-related proteins.

Show MeSH
Related in: MedlinePlus