| Carboxyfluorescein FLICA Assays for Detection of Caspase Activity
The FLICA Apoptosis Detection Kits use a novel approach to detect active caspases. The methodology is based on a Fluorochrome Inhibitor of Caspases (FLICA). Once inside the cell, the FLICA inhibitor binds covalently to the active caspase2. These inhibitors are cell permeable and non-cytotoxic. For detection using green fluorescence, a carboxyfluorescein-labeled fluoromethyl ketone peptide inhibitor of caspases is used.
ICT also offers Sulforhodamine FLICA assays that use red fluorescence.
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Figure 1. Suspension cells were incubated with 1 mM staurosporine for 3 hours at 377C to induce apoptosis. Cells were then labeled with FAM-VAD-FMK (a generic FLICA probe which binds to many activated caspases) for 60 minutes at 377C. Cells were washed, then Hoechst stain was added and the cells were incubated for 5 minutes. Wet-mount slides were prepared and 2 photos were taken of the same cells. Caspase activity on the left (photo A) was detected using a band pass filter (excitation at 488 nm, emission at 520 nm). Nuclear staining by Hoechst stain on the right (photo B) was revealed using a UV-filter (excitation at 365 nm, emission at 480 nm). |
In Figure 1, photo A, only one cell appears green it is apoptotic and stained positive for poly caspase activity with the FAM-VAD-FMK reagent. The other cell, which is not visible, did not bind to the reagent and therefore is not apoptotic. The same cells, photographed at right under a different wavelength for Hoechst stain, appear blue. The cell in the top right of photo B (which appears green in photo A) has a very brightly stained nucleus its DNA is condensing in the cell, a sign it is dying. The cell in the bottom left of photo B (which is not visible in photo A) does not have a brightly stained nucleus, therefore it is neither apoptotic nor necrotic.
User Manual
Ordering Information
References:
Slee, E. A., C. Adrain, and S. J. Maritin. 1999. Serial Killers: ordering caspase activation events in apoptosis.Cell Death and Differ. 6:1067-1074.
Ekert, P. G., J. Silke and D. L. Vaux. 1999. Caspase inhibitors. Cell Death and Differ. 6:1081-1086.
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