Actin filaments regulate microtubule growth at the centrosome. (2019)
Figure 2

Figure 2: The impact of modulating centrosomal actin on microtubules in B lymphocytes.

IIA1.6 B lymphoma cells were treated 45 min with indicated inhibitors (CK666 at 25 µM, SMIFH2 at 25µM) or DMSO as control prior to being fixed and stained for α-tubulin (left column) and F-actin (right column). Scale bar: 3 µm.

Histograms show the quantifications of the amount of polymerized fluorescent tubulin (right, values were normalized with respect to the mean of control condition) and filamentous actin at the centrosome (left, values correspond to the fraction of fluorescence in a 2-micron-wide area around the centrosome relative to the total fluorescence in the cell). Measurements were pooled from 3 independent experiments; DMSO: n= 91, CK666: n= 82, SMIFH2: n= 74, latrunculinA: n= 96. Error bars correspond to standard deviations. P values were calculated with Mann-Whitney test.

Percentage differences of centrosomal F-actin and microtubule fluorescence intensities in cells treated with cytoskeleton inhibitors in comparison with the respective densities in cells treated with DMSO. Errors bars represent standard deviations. P values were calculated with one-sample t-test (i.e. comparison to a theoretical mean of "0").

The graph shows the same measurements as in panel (B) in an XY representation of individual measurements. The three lines correspond to linear regressions of the three sets of data relative to cells stimulated with each actin drug.

IIA1.6 B lymphoma cells were transfected to transiently express centrin1-GFP (red) and EB3-mCherry (green) and video-recorded at the contact site with the glass coverslip (left) and at the centrosome (right). Scale bar: 3 µm.

The duration of EB3-positive comets presence in the bottom plane was measured in DMSO and CK666 treated cells (left). Error bars correspond to standard deviations. The number of EB3-positive comets exiting the a 2-µm wide centrosomal area was also compared between the two conditions (right). In both cases P values were calculated with Mann-Whitney test.

IIA1.6 B lymphoma cells were transfected to transiently express centrin1-VCA-GFP (bottom) or centrin1-GFP (top) as control prior to be fixed and stained for α-tubulin (left column) and F-actin (middle column). The GFP signal of centrin1 or centrin1-VCA is shown in the right column to illustrate the proper centrosome targeting. Scale bar: 3 µm.

Histograms show the quantifications of the amount of polymerized fluorescent tubulin (right) and filamentous actin at the centrosome (left). Values correspond to the fraction of fluorescence in a 2-micron-wide area around the centrosome relative to the total fluorescence in the cell. Measurements were pooled from 3 independent experiments; centrin1-GFP: n= 88, centrin1-VCA-GFP: n= 87. Errors bars represent standard deviations. P values were calculated with Mann-Whitney test.

Percentage differences of F-actin and microtubule fluorescence intensities at the centrosome were compared in cells transfected either with centrin1-VCA-GFP or with centrin1-GFP. Errors bars represent standard deviations. P values were calculated with one-sample t-test (i.e. comparison to a theoretical mean of "0").

The graph shows the variations of the total amount of tubulin per cell with respect to the content of actin at the centrosome. The two lines correspond to linear regressions of the two sets of data relative to cells transfected with centrin1-VCA-GFP or centrin1-GFP.