Cleavage of membrane-anchored growth factors involves distinct protease activities regulated through common mechanisms.
The membrane-anchored forms of transforming growth factor-alpha (TGF-alpha) and stem cell growth factors (Kit ligands) KL-1 and KL-2 are converted to soluble growth factor forms by a regulated proteolytic cleavage process. Each of these proteins is cleaved at a distinct site, however their cleavage is activated via a common set of intracellular signaling mechanisms. By using a panel of protease inhibitors, we show here that at least two cell-associated serine protease activities with distinct specificities participate in membrane growth factor cleavage. Two serine protease inhibitors of broad specificity, diisopropylfluorophosphate and 3,4-dichloroisocoumarin, prevent the cleavage of proTGF-alpha and KL-1 but not that of KL-2. Of the agents tested, N-tosyl-L-phenylalanine chloromethyl ketone and various haloenol lactone derivatives are the most potent inhibitors of cleavage of all three membrane growth factors. It is concluded that cleavage of membrane-anchored growth factors involves a proteolytic system with multiple serine protease activities regulated through common mechanisms.
Pandiella
A
A
Cell Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York 10021.
Bosenberg
M W
MW
Huang
E J
EJ
Besmer
P
P
Massagué
J
J
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D010450:Endopeptidases / Q000378:metabolism*; D016298:Hematopoietic Cell Growth Factors / Q000096:biosynthesis* / Q000235:genetics; D007531:Isoflurophate / Q000494:pharmacology; D007700:Kinetics; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000494:pharmacology*; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D051381:Rats; D017386:Sequence Homology, Amino Acid; D019089:Stem Cell Factor; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D016211:Transforming Growth Factor alpha / Q000096:biosynthesis* / Q000235:genetics
D016298:Hematopoietic Cell Growth Factors; D011480:Protease Inhibitors; D011498:Protein Precursors; D019089:Stem Cell Factor; D016211:Transforming Growth Factor alpha; D007531:Isoflurophate; D010450:Endopeptidases; D013755:Tetradecanoylphorbol Acetate