Cathepsin L increased level upon Ras mutants expression: the role of p38 and p44/42 MAPK signaling pathways.
The involvement of Ras and three major Ras effectors, Raf, phosphatidylinositol 3-kinase (PI3K) and Ral guanine nucleotide exchange factor in the regulation of lysosomal proteases cathepsin L and B in human fibroblasts was compared. We found that cathepsin L cell content was increased by active Ras overexpression through Raf- and PI3K-mediated signaling pathways, while cathepsin B processing was altered by active Ras overexpression. Cathepsin L increased level following active Ras overexpression correlates with an increase of p38 MAPK activation and content and with an increase of p44/42 MAPK activation, so we investigated the role of these signaling pathways using pharmacological inhibitors. Unexpectedly, the p38 MAPK inhibitor SB203580 produced an increase of cathepsin L content, while the p44/42 MAPK signaling cascade inhibitor U0126 produced a remarkable shift of cathepsin L processing in favor of procathepsin L. In both cases, cathepsin B level and processing were not affected. The analysis of CTSL1 gene transcript demonstrated that cathepsin L protein and transcript correlate both in fibroblasts expressing Ras mutants and in pharmacologically treated cells, thus indicating a transcriptional up-regulation.
Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy.
Lorena
L
Urbanelli
Francesco
F
Trivelli
Luisa
L
Ercolani
Eleonora
E
Sementino
Alessandro
A
Magini
Brunella
B
Tancini
Raffaella
R
Franceschini
Carla
C
Emiliani
D001483:Base Sequence; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D056668:Cathepsin L / Q000378:metabolism*; D002460:Cell Line; D017931:DNA Primers; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
D002070:Butadienes; D017931:DNA Primers; D007093:Imidazoles; D009570:Nitriles; D047428:Protein Kinase Inhibitors; D011725:Pyridines; C113580:U 0126; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D056668:Cathepsin L; D018631:ras Proteins; C093642:SB 203580