Annexin-A5 assembled into two-dimensional arrays promotes cell membrane repair.
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.
Affiliation: Molecular Imaging and NanoBioTechnology, IECB, UMR-5248 CBMN CNRS-University Bordeaux1-ENITAB, Talence F-33402, France.Show MeSH
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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.
Affiliation: Molecular Imaging and NanoBioTechnology, IECB, UMR-5248 CBMN CNRS-University Bordeaux1-ENITAB, Talence F-33402, France.