Module 8: Figure nuclear import of NFAT

Frequency-dependent nuclear import of nuclear factor of activated T cells (NFAT) in skeletal muscle fibres.

Fibres injected with nuclear factor of activated T cells (NFAT)/green fluorescent protein (GFP) were stimulated electrically at either 1 or 10 Hz. A and B. At 1 Hz stimulation, the NFAT/GFP, which is diffusely distributed throughout the fibre, is not evident. C and D. Fibres were stimulated for 30 min at 1 Hz and then for a further 30 min at 10 Hz. Following the faster stimulation, the NFAT/GFP gradually began to appear in the nucleus, where it was concentrated in distinct foci. In separate experiments, the half-time (t½) for import was approximately 15 min, whereas the export was very much slower, with a t½ value of 90 min. For another example of how varying the frequency can alter the nuclear transcription of NFAT, see Module 6: Figure NFAT nuclear translocation. Reproduced from The Journal of Cell Biology, 2001, vol. 155, pp. 27–40, by copyright permission of The Rockefeller University Press; see Liu et al. 2001.