“Panta rhei” Perpetual cycling of the keratin cytoskeleton
Leube RE, Moch M, Kölsch A, Windoffer R, 2011
The filamentous cytoskeletal systems fulfil seemingly incompatible functions by maintaining a stable scaffolding to ensure tissue integrity and simultaneously facilitating rapid adaptation to intracellular processes and environmental stimuli. This paradox is particularly obvious for the abundant keratin intermediate filaments in epithelial tissues. The epidermal keratin cytoskeleton, for example, supports the protective and selective barrier function of the skin while enabling rapid growth and remodelling in response to physical, chemical and microbial challenges. We propose that these dynamic properties are linked to the perpetual re-cycling of keratin intermediate filaments that we observe in cultured cells.
This cycle of assembly and disassembly is independent of protein biosynthesis and consists of distinct, temporally and spatially defined steps. In this way, the keratin cytoskeleton remains in constant motion but stays intact and is also able to restructure rapidly in response to specific regulatory cues as is needed, e.g., during division, differentiation and wound healing.
Keratin filament network dynamics in vulvar carcinoma-derived AK13-1 cells producing human keratin 13-enhanced green fluorescent protein hybrids HK13-EGFP (Windoffer and Leube, 1999).
Fluorescence of HK13-EGFP was recorded (30 s intervals; display rate 15 frames/s) in a single focal plane by confocal laser scanning microscopy.