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Spontaneous and electric field-controlled front-rear polarization of human keratinocytes.

Saltukoglu D, Grünewald J, Strohmeyer N, Bensch R, Ulbrich MH, Ronneberger O, Simons M - Mol. Biol. Cell (2015)

Bottom Line: By contrast, we found a crucial role for extracellular pH as well as G protein coupled-receptor (GPCR) or purinergic signaling in the control of directionality.Overall our work puts forward a model in which the EF uses distinct polarization pathways.The cathodal pathway involves GPCR/purinergic signaling and is dominant over the anodal pathway at neutral pH.

View Article: PubMed Central - PubMed

Affiliation: Center for Systems Biology, University of Freiburg, 79104 Freiburg, Germany Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany Spemann Graduate School of Biology and Medicine, University of Freiburg, 79104 Freiburg, Germany BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.

No MeSH data available.


Related in: MedlinePlus

Lowering pHe reverses the direction of symmetry breaking. (A) Quantification of morphologies of cells bathing in low pHe with and without EF. The number of cells quantified is indicated above each column. (B) Rose plot representing the direction of symmetry breaking in low-pH medium. (C) Automated boundary detection from phase contrast videos and the associated protrusion/retraction maps constructed from boundary movements in time for the conditions of low- and normal-pH medium with and without EF. In the detected boundaries, time progression is represented from blue to red. In the protrusion/retraction maps, the x-axis represents the time, and the y-axis is the position of the cellular boundary from 0 to 2π. Representative cells have been turned at the indicated angles so that their leading edges always face the right side. Symmetry breaking in the normal-pH condition (with and without EF), as well as low-pH condition (without EF), is featured by front protrusions preceding the retraction of the back. By contrast, at low pH (with EF), there is an invagination of the cellular boundary at the lagging edge. The invagination event is represented by the unique conical shape of the blue retraction area of the corresponding protrusion/retraction map. Moreover, there is also a general reduction of leading-edge protrusion and cell translocation speed during polarization in this condition.
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Figure 5: Lowering pHe reverses the direction of symmetry breaking. (A) Quantification of morphologies of cells bathing in low pHe with and without EF. The number of cells quantified is indicated above each column. (B) Rose plot representing the direction of symmetry breaking in low-pH medium. (C) Automated boundary detection from phase contrast videos and the associated protrusion/retraction maps constructed from boundary movements in time for the conditions of low- and normal-pH medium with and without EF. In the detected boundaries, time progression is represented from blue to red. In the protrusion/retraction maps, the x-axis represents the time, and the y-axis is the position of the cellular boundary from 0 to 2π. Representative cells have been turned at the indicated angles so that their leading edges always face the right side. Symmetry breaking in the normal-pH condition (with and without EF), as well as low-pH condition (without EF), is featured by front protrusions preceding the retraction of the back. By contrast, at low pH (with EF), there is an invagination of the cellular boundary at the lagging edge. The invagination event is represented by the unique conical shape of the blue retraction area of the corresponding protrusion/retraction map. Moreover, there is also a general reduction of leading-edge protrusion and cell translocation speed during polarization in this condition.

Mentions: Another way to influence directionality in electrotaxis is through change in extracellular pH. This effect has been proposed to be due to the change in charge on the surface of the plasma membrane (Allen et al., 2013). Therefore we examined the effect of acidifying the extracellular pH (pHe) to 6.6 in our system. Although this treatment slightly reduced the ability of the cells to polarize, it also led to reversal of the polarization direction, with 79% of all cells polarizing toward the anode (Figure 5, A and B, and Supplemental Movie S9). After migration, trajectories revealed that the cells that polarized toward the anode were still able to electrotax toward the anode (Supplemental Figure S5, A and B). In low pHe, cells had a directionality index of −0.54, compared with 0.66 for cells in normal-pH medium. Nonetheless, anodal migration was less efficient than cathodal migration, with significantly lower average track length, straightness, and displacement value (Supplemental Figure S5, C–E).


Spontaneous and electric field-controlled front-rear polarization of human keratinocytes.

Saltukoglu D, Grünewald J, Strohmeyer N, Bensch R, Ulbrich MH, Ronneberger O, Simons M - Mol. Biol. Cell (2015)

Lowering pHe reverses the direction of symmetry breaking. (A) Quantification of morphologies of cells bathing in low pHe with and without EF. The number of cells quantified is indicated above each column. (B) Rose plot representing the direction of symmetry breaking in low-pH medium. (C) Automated boundary detection from phase contrast videos and the associated protrusion/retraction maps constructed from boundary movements in time for the conditions of low- and normal-pH medium with and without EF. In the detected boundaries, time progression is represented from blue to red. In the protrusion/retraction maps, the x-axis represents the time, and the y-axis is the position of the cellular boundary from 0 to 2π. Representative cells have been turned at the indicated angles so that their leading edges always face the right side. Symmetry breaking in the normal-pH condition (with and without EF), as well as low-pH condition (without EF), is featured by front protrusions preceding the retraction of the back. By contrast, at low pH (with EF), there is an invagination of the cellular boundary at the lagging edge. The invagination event is represented by the unique conical shape of the blue retraction area of the corresponding protrusion/retraction map. Moreover, there is also a general reduction of leading-edge protrusion and cell translocation speed during polarization in this condition.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4666133&req=5

Figure 5: Lowering pHe reverses the direction of symmetry breaking. (A) Quantification of morphologies of cells bathing in low pHe with and without EF. The number of cells quantified is indicated above each column. (B) Rose plot representing the direction of symmetry breaking in low-pH medium. (C) Automated boundary detection from phase contrast videos and the associated protrusion/retraction maps constructed from boundary movements in time for the conditions of low- and normal-pH medium with and without EF. In the detected boundaries, time progression is represented from blue to red. In the protrusion/retraction maps, the x-axis represents the time, and the y-axis is the position of the cellular boundary from 0 to 2π. Representative cells have been turned at the indicated angles so that their leading edges always face the right side. Symmetry breaking in the normal-pH condition (with and without EF), as well as low-pH condition (without EF), is featured by front protrusions preceding the retraction of the back. By contrast, at low pH (with EF), there is an invagination of the cellular boundary at the lagging edge. The invagination event is represented by the unique conical shape of the blue retraction area of the corresponding protrusion/retraction map. Moreover, there is also a general reduction of leading-edge protrusion and cell translocation speed during polarization in this condition.
Mentions: Another way to influence directionality in electrotaxis is through change in extracellular pH. This effect has been proposed to be due to the change in charge on the surface of the plasma membrane (Allen et al., 2013). Therefore we examined the effect of acidifying the extracellular pH (pHe) to 6.6 in our system. Although this treatment slightly reduced the ability of the cells to polarize, it also led to reversal of the polarization direction, with 79% of all cells polarizing toward the anode (Figure 5, A and B, and Supplemental Movie S9). After migration, trajectories revealed that the cells that polarized toward the anode were still able to electrotax toward the anode (Supplemental Figure S5, A and B). In low pHe, cells had a directionality index of −0.54, compared with 0.66 for cells in normal-pH medium. Nonetheless, anodal migration was less efficient than cathodal migration, with significantly lower average track length, straightness, and displacement value (Supplemental Figure S5, C–E).

Bottom Line: By contrast, we found a crucial role for extracellular pH as well as G protein coupled-receptor (GPCR) or purinergic signaling in the control of directionality.Overall our work puts forward a model in which the EF uses distinct polarization pathways.The cathodal pathway involves GPCR/purinergic signaling and is dominant over the anodal pathway at neutral pH.

View Article: PubMed Central - PubMed

Affiliation: Center for Systems Biology, University of Freiburg, 79104 Freiburg, Germany Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany Spemann Graduate School of Biology and Medicine, University of Freiburg, 79104 Freiburg, Germany BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.

No MeSH data available.


Related in: MedlinePlus