Contribution of cathepsin L to secretome composition and cleavage pattern of mouse embryonic fibroblasts
01.11.2011
Tholen S, Biniossek ML, Geßler AL, Müller S, Weißer J, Kizhakkedathu JN, Reinheckel T, Schilling O
Biol Chem. 2011;392(11):961-971
The protease cathepsin L is secreted from cells in a variety of pathological conditions such as cancer and arthritis. We compared the secretome composition and extracellular proteolytic cleavage events in cell supernatants of cathepsin L-deficient and wild-type mouse embryonic fibroblasts (MEFs). Quantitative proteomic comparison of cell conditioned media indicated that cathepsin L deficiency affects, albeit in a limited manner, the abundances
of extracellular matrix components, signaling proteins, proteases and endogenous protease inhibitors. To characterize cathepsin L contribution to extracellular proteolysis, we performed terminal amine isotopic labeling of substrates (TAILS), an N-terminomic technique for the identification and quantification of native and proteolytically generated protein N-termini. TAILS identified > 1500 protein N-termini. Cathepsin L deficiency predominantly reduced the magnitude of collagenous cleavage sites C-terminal to a proline residue (see Figure). This contradicts cathepsin L active site specificity and indicates altered activity of further proteases as a result of cathepsin L ablation.
