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Annexin-A5 assembled into two-dimensional arrays promotes cell membrane repair.

Bouter A, Gounou C, Bérat R, Tan S, Gallois B, Granier T, d'Estaintot BL, Pöschl E, Brachvogel B, Brisson AR - Nat Commun (2011)

Bottom Line: Compared with wild-type mouse perivascular cells, AnxA5- cells exhibit a severe membrane repair defect.In contrast, an AnxA5 mutant that lacks the ability of forming 2D arrays is unable to promote membrane repair.We propose that AnxA5 participates in a previously unrecognized step of the membrane repair process: triggered by the local influx of Ca(2+), AnxA5 proteins bind to torn membrane edges and form a 2D array, which prevents wound expansion and promotes membrane resealing.

View Article: PubMed Central - PubMed

Affiliation: Molecular Imaging and NanoBioTechnology, IECB, UMR-5248 CBMN CNRS-University Bordeaux1-ENITAB, Talence F-33402, France.

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Responses of wt-PV and AnxA5- PV cells to 80-mW infrared irradiation.(a) Representative image series showing the response of an AnxA5- PV cell to 80-mW infrared irradiation. The cell presents a macroscopic membrane rupture at the irradiated area and a large increase of cytoplasmic fluorescence intensity, as observed at 160 mW. (b,c) Image series showing two types of response for wt-PV cells irradiated at 80 mW. (b) A minor fraction (about 30%) of wt-PV cells presents an increase in cytoplasmic fluorescence intensity, yet no macroscopic membrane rupture. (c) The major fraction (about 70%) of wt-PV cells shows no increase in cytoplasmic fluorescence intensity. The areas of membrane irradiation are marked with a white arrow before irradiation and a red arrow after irradiation. Scale bars, 10 μm.
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f3: Responses of wt-PV and AnxA5- PV cells to 80-mW infrared irradiation.(a) Representative image series showing the response of an AnxA5- PV cell to 80-mW infrared irradiation. The cell presents a macroscopic membrane rupture at the irradiated area and a large increase of cytoplasmic fluorescence intensity, as observed at 160 mW. (b,c) Image series showing two types of response for wt-PV cells irradiated at 80 mW. (b) A minor fraction (about 30%) of wt-PV cells presents an increase in cytoplasmic fluorescence intensity, yet no macroscopic membrane rupture. (c) The major fraction (about 70%) of wt-PV cells shows no increase in cytoplasmic fluorescence intensity. The areas of membrane irradiation are marked with a white arrow before irradiation and a red arrow after irradiation. Scale bars, 10 μm.

Mentions: To gain further insight into these processes, we selected irradiation conditions for which wt-PV and AnxA5- PV cells showed most distinct responses. At reduced laser intensity (80 mW), AnxA5- PV cells responded as described above at 160 mW, with large membrane ruptures and absence of resealing (Fig. 3a; Supplementary Fig. S2b). On the other hand, wt-PV cells presented two types of response. About 30% of wt-PV cells exhibited an increase of cytoplasmic fluorescence (Fig. 3b), which was significantly smaller (about ×3) than at 160 mW. Strikingly, none of these cells showed a macroscopic membrane rupture. We propose that the laser beam creates membrane microruptures, which allow the FM1-43 to enter, but are too small to be resolved. Most of wt-PV cells (∼70%) showed no detectable increase in cytoplasmic fluorescence (Fig. 3c). This indicates either that these cells were not damaged or, on the contrary, that membranes ruptured and rapidly repaired. The possibility that these cells were not properly irradiated is ruled out by the systematic observation of a complete photobleaching of FM1-43 dyes at irradiation sites (thin white arrow in Fig. 3c, frame 2; Supplementary Fig. S3). Therefore, we conclude that most wt-PV cells (about 70%) present a rapid resealing of membrane microruptures at reduced laser irradiation.


Annexin-A5 assembled into two-dimensional arrays promotes cell membrane repair.

Bouter A, Gounou C, Bérat R, Tan S, Gallois B, Granier T, d'Estaintot BL, Pöschl E, Brachvogel B, Brisson AR - Nat Commun (2011)

Responses of wt-PV and AnxA5- PV cells to 80-mW infrared irradiation.(a) Representative image series showing the response of an AnxA5- PV cell to 80-mW infrared irradiation. The cell presents a macroscopic membrane rupture at the irradiated area and a large increase of cytoplasmic fluorescence intensity, as observed at 160 mW. (b,c) Image series showing two types of response for wt-PV cells irradiated at 80 mW. (b) A minor fraction (about 30%) of wt-PV cells presents an increase in cytoplasmic fluorescence intensity, yet no macroscopic membrane rupture. (c) The major fraction (about 70%) of wt-PV cells shows no increase in cytoplasmic fluorescence intensity. The areas of membrane irradiation are marked with a white arrow before irradiation and a red arrow after irradiation. Scale bars, 10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3104517&req=5

f3: Responses of wt-PV and AnxA5- PV cells to 80-mW infrared irradiation.(a) Representative image series showing the response of an AnxA5- PV cell to 80-mW infrared irradiation. The cell presents a macroscopic membrane rupture at the irradiated area and a large increase of cytoplasmic fluorescence intensity, as observed at 160 mW. (b,c) Image series showing two types of response for wt-PV cells irradiated at 80 mW. (b) A minor fraction (about 30%) of wt-PV cells presents an increase in cytoplasmic fluorescence intensity, yet no macroscopic membrane rupture. (c) The major fraction (about 70%) of wt-PV cells shows no increase in cytoplasmic fluorescence intensity. The areas of membrane irradiation are marked with a white arrow before irradiation and a red arrow after irradiation. Scale bars, 10 μm.
Mentions: To gain further insight into these processes, we selected irradiation conditions for which wt-PV and AnxA5- PV cells showed most distinct responses. At reduced laser intensity (80 mW), AnxA5- PV cells responded as described above at 160 mW, with large membrane ruptures and absence of resealing (Fig. 3a; Supplementary Fig. S2b). On the other hand, wt-PV cells presented two types of response. About 30% of wt-PV cells exhibited an increase of cytoplasmic fluorescence (Fig. 3b), which was significantly smaller (about ×3) than at 160 mW. Strikingly, none of these cells showed a macroscopic membrane rupture. We propose that the laser beam creates membrane microruptures, which allow the FM1-43 to enter, but are too small to be resolved. Most of wt-PV cells (∼70%) showed no detectable increase in cytoplasmic fluorescence (Fig. 3c). This indicates either that these cells were not damaged or, on the contrary, that membranes ruptured and rapidly repaired. The possibility that these cells were not properly irradiated is ruled out by the systematic observation of a complete photobleaching of FM1-43 dyes at irradiation sites (thin white arrow in Fig. 3c, frame 2; Supplementary Fig. S3). Therefore, we conclude that most wt-PV cells (about 70%) present a rapid resealing of membrane microruptures at reduced laser irradiation.

Bottom Line: Compared with wild-type mouse perivascular cells, AnxA5- cells exhibit a severe membrane repair defect.In contrast, an AnxA5 mutant that lacks the ability of forming 2D arrays is unable to promote membrane repair.We propose that AnxA5 participates in a previously unrecognized step of the membrane repair process: triggered by the local influx of Ca(2+), AnxA5 proteins bind to torn membrane edges and form a 2D array, which prevents wound expansion and promotes membrane resealing.

View Article: PubMed Central - PubMed

Affiliation: Molecular Imaging and NanoBioTechnology, IECB, UMR-5248 CBMN CNRS-University Bordeaux1-ENITAB, Talence F-33402, France.

Show MeSH
Related in: MedlinePlus