Apoptosis-induced cleavage of keratin 15 and keratin 17 in a human breast epithelial cell line

Keratin 15(K15)and keratin 17(K17)are intermediate filament (IF) type I pro teins that are responsible for the mechanical integrity of epithelial cells . By analyzing the human breast epithelial cell line H184A1 before and afte r induction of apoptosis by high-resolution two dimensional gel electrophor esis (2-DE) we identified the caspase-mediated cleavage of keratins 15 and 17. After induction of apoptosis three fragments of both K15 and K17 could be observed by 2-DE. K15 and K17 proteolysis was observed during staurospor ine-induced apoptosis and anoikis (anchorage-dependent apoptosis) as well a nd was shown to be caspase-dependent. By using mass spectrometry we could d etermine the caspase cleavage sites, one in K15 and two in K17, The sequenc e VEMD/A at the cleavage site located in the conserved linker region was fo und in K15 and K17, A further cleavage site was identified in the tail regi on of K17 with the recognition motif EVQD/G.